International Fertilizer Development Center - Analytical Manual

IFDC

Fertilizer

Analytical

Manual

IFDC

Fertilizer

Analytical

Manual

ForewordForeword

Since fertilizers are sold (and guaranteed) according to their nutrientcomposition, it is necessary to have available analytical methods to accuratelydetermine the plant nutrient content.

Fertilizers provide all essential plant nutrient elements except carbon,hydrogen, and oxygen. The total number of essential elements is generally agreed tobe 18 and of the 15 that may come from fertilizers, methods of analysis for all but one(molybdenum) are included in this manual. Several different methods of analysis formost all of these elements exist with some being more accurate than others and somebeing more elaborate or expensive to apply.

The methods of analysis included in this manual are all based on methodsadopted by AOAC International [formerly Association of Official Analytical Chemists(AOAC)] or the International Organization for Standardization (ISO). AOAC and ISOmethods have been studied rigorously by multi-laboratory groups and exposed tosophisticated statistical protocols before adoption. They are recognized as worldstandards by fertilizer authorities and scientists.

Besides the methods detailed in this manual, there are others that arerecognized internationally and may be more appropriate for your requirements.Examples are the methods of analysis of the European Union and Japan. Additionally,because IFDC laboratories are largely research oriented, we have adopted and/ordeveloped project-specific methods of analysis that are not recognized as standardnational or international methods and are not included in this manual. If you have aparticular need for analyzing a material that is not covered by any of the methodsdescribed in this manual, feel free to contact IFDC to ascertain if we have knowledgeof methodology that may be suitable for analyzing your specific material.

In addition to the individual methods presented, the manual also providesimportant general reference material in the appendixes. This information can be ahelpful guide in promoting uniformity and efficiency. Appendix A presents methodsfor the preparation of standard acids and bases. Appendix B shows an analytical reportform. Appendix C summarizes some very valuable information on laboratory safety.Appendix D includes three typical job descriptions that may be useful in classifyingtechnical personnel in the laboratory.

We believe that the information in this manual is true and accurate. Anyrecommendations or suggestions are made without warranty or guaranty of any kind.Consequently, IFDC shall not be responsible for any incidental or consequentialdamages resulting from the use of the procedures in this manual whatsoever.

The procedures in this manual may involve hazardous materials, operations,and equipment. These procedures do not purport to address the safety problemsassociated with their use. It is the responsibility of the user of these procedures toestablish appropriate safety and health practices and determine the applicability ofregulatory limitations prior to use.

This manual was prepared by the International Fertilizer Development Center.

Abbreviations, Acronyms, Definitions, Abbreviations, Acronyms, Definitions, and Safety Notesand Safety Notes

AbbreviationsAbbreviationskg = kilogramg = grammg = milligramµg = microgramL = litermL = milliliterµL = microlitercm = centimetermm = millimeternm = nanometerN = normalityA = absorbance

AcronymsAcronymsISO = International Organization for StandardizationDIS = draft international standardCD = committee draft

DefinitionsDefinitions1. "Water" or "H2O" means distilled or deionized water.

2. In expressions (1 + 2), (5 + 4), etc., used in connection with liquidreagents, the first number refers to volume of reagent and the second tovolume of water.

3. In solutions defined in percentage, it is understood that the solution isprepared as weight of reagent in volume of solution, unless otherwisedescribed.

4. "Sulfuric acid, nitric acid," etc., when not further defined, meansconcentrated reagent grade.

5. All reagents, unless otherwise described, are of recognized analyticalgrade.

6. "Ordinary labware" means labware normally stocked in fertilizerlaboratories and includes items such as balances, pH meter, glassware,stirrers, etc.

7. All volumetric glassware listed conforms to ISO specifications.

8. Temperature is expressed as degrees Celsius.

9. The term "alcohol" means 95% ethanol unless otherwise specified.

Safety NotesSafety NotesPerchloricPerchloric AcidAcid —— WARNINGWARNING: Fuming hot perchloric acid is a powerfuloxidizing agent and will react explosively with organic matter. Many inorganicsalts of perchloric acid are unstable and will decompose violently if taken todryness or baked. All perchloric acid dissolutions should be preceded bypreliminary oxidation with nitric acid, and nitric acid should be present insolution when dilute perchloric solutions are to be concentrated to fuming. If,in spite of these precautions, such a solution changes color from light yellowto dark brown or black, dilute immediately with water or leave the vicinityhurriedly. Fume hoods used for perchloric acid should be constructed ofinorganic material, preferably stainless steel, and equipped to be washed outperiodically. Under no circumstances should such hoods be used for heatingorganic solvents or in other situations where combustible fumes or dust areproduced.

LaboratoryLaboratory SSafe tya fe ty — Refer to Laboratory Safety Guidelines found inAppendix C.

Table of ContentsTable of Contents

PageSample Reduction and Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Total Nitrogen — Modified Comprehensive Method (N-1) . . . . . . . . . . . . . . . . . . . . . . . 7

Ammoniacal Nitrogen — Distillation-Titrimetric Method (N-2) . . . . . . . . . . . . . . . . . . 10Ammoniacal and Nitrate Nitrogen — Devarda Method (N-3) . . . . . . . . . . . . . . . . . . . 12

Biuret — Spectrometric Method (N-4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Total Phosphorus — Preparation of Sample Solution (P-1) . . . . . . . . . . . . . . . . . . . . . . 16

Water-Soluble Phosphorus — Preparation of Sample Solution (P-2) . . . . . . . . . . . . . . 18

Citrate-Insoluble Phosphorus — Preparation of Sample Solution (P-3) . . . . . . . . . . . . 20Direct-Available Phosphorus — Preparation of Sample Solution (P-4) . . . . . . . . . . . . 22

Phosphorus — Gravimetric Quimociac Method (P-5) . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Phosphorus — Alkalimetric Quimociac Method (P-6) . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Phosphorus — Spectrometric Molybdovanadate Method (P-7) . . . . . . . . . . . . . . . . . . . 30

Potassium — Gravimetric Tetraphenylborate Method (K-1) . . . . . . . . . . . . . . . . . . . . . . 33Potassium — Titrimetric Tetraphenylborate Method (K-2) . . . . . . . . . . . . . . . . . . . . . . . 36

Potassium — Atomic Emission Method (K-3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Calcium — Potassium Permanganate Method (Ca-1) . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Calcium — Atomic Absorption Spectrometric Method (Ca-2) . . . . . . . . . . . . . . . . . . . . 44

Magnesium — Atomic Absorption Spectrometric Method (Mg-1) . . . . . . . . . . . . . . . . . 47Sulfur — Gravimetric Barium Sulfate Method (S-1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Boron — Azomethine H Spectrometric Method (B-1) . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Chloride — Titrimetric Silver Nitrate Method (Cl-1) . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Cobalt — Atomic Absorption Spectrometric Method (Co-1) . . . . . . . . . . . . . . . . . . . . . 58

Copper — Atomic Absorption Spectrometric Method (Cu-1) . . . . . . . . . . . . . . . . . . . . . 62Iron — Atomic Absorption Spectrometric Method (Fe-1) . . . . . . . . . . . . . . . . . . . . . . . . 66

Manganese — Atomic Absorption Spectrometric Method (Mn-1) . . . . . . . . . . . . . . . . . 70

Sodium — Atomic Emission Spectrometric Method (Na-1) . . . . . . . . . . . . . . . . . . . . . . 74

Zinc — Atomic Absorption Spectrometric Method (Zn-1) . . . . . . . . . . . . . . . . . . . . . . . 76

Free Water — Vacuum-Desiccation Method (H2O-1) . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Appendix A. Preparation of Standard Solutions

Appendix B. Analytical Report Form

Appendix C. Laboratory Safety

Appendix D. Job Descriptions

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Sample Reduction and PreparationSample Reduction and Preparation

ScopeScopeSamples received in the laboratory must be reduced in mass to 225-500 g,pulverized, if necessary reduced in mass again, and stored in airtight containers.Procedures have been developed to standardize those manipulations necessaryto reduce and prepare solid fertilizer samples. It is recommended that theseprocedures be carried out in a laboratory environment.

ApparatusApparatus 1. Sample Reducer or Riffle — A gated-riffle (Figure 1) constructed of

corrosion-resistant material is required. The size of the riffle shall beappropriate to the quantity of sample being reduced. Receiving pans mustfit riffle from end to end of partitioned section.

For most unground fertilizer samples, the slot openings should be aminimum of 12 mm.

2. Grinder or Sample Pulverizer — A grinder shall perform as required for theprocedure without changing the composition of the sample.

3. Sieves, 2 — Each 200 mm in diameter, with openings of 0.5 and 1.0 mm,constructed of brass or stainless steel. Stainless steel sieves arerecommended for samples to be analyzed for micronutrients.

4. Containers for Ground Samples — Plastic or glass, 250 mL capacity, widemouth with airtight cap.

ProcedureProcedureReduction of Unground SampleReduction of Unground Sample 1. Make sure that all equipment is clean.

2. Set gated-riffle in level position, not tilted in any direction.

3. Place the two empty receiving pans in position beneath the riffle.

4. Transfer the composite sample to the hopper of the riffle.

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5. Open the gate fully and allow the entire sample to flow into the pansbeneath the riffle, forming two equal portions.

6. If required, repeat steps 4 and 5, until sample is reduced to approximately500 g. (If desired, retain the second half as reserve, until the preparationis completed on the portion to be analyzed.)

7. Transfer final sample to moistureproof containers and mark foridentification.NoteNote: The container must be large enough to hold the entire final sample.

None should be discardedNone should be discarded. If the only available container is too small,sample may be reduced by riffling twice and saving one-half at each step,resulting in one-fourth of the original sample, but must not be less than250 g.

8. Clean equipment before storing or re-use.

Preparation of SamplePreparation of Sample 1. Grind the entire sample after reduction. If further reduction to less than

250 g is desired, this must be done only on the ground sample.

2. Grind dry fertilizer mixtures to pass 0.5 mm sieve.

3. Fertilizer materials and moist fertilizer mixtures may be ground to passsieve with 1.0-mm openings.

4. Grind as rapidly as possible to avoid loss or gain of moisture during thegrinding operation, but avoid overheating the sample.

5. Periodically check the efficiency of the grinding mill screen by sieving theentire ground sample, including brushings from grinding mill, through a0.5 mm sieve. Regrind oversize with a mortar and pestle and install newscreens if necessary.

6. Place entire sample on flexible rolling sheet of glazed butcher's paper,smooth oil cloth, or polyethylene sheet for mixing.

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7. Roll sample slowly from four directions until sample has been thoroughlymixed — 20 times is usually considered adequate. Rolling too rapidly willcause sliding and no mixing.

8. After completion of mixing, roll sample into a pile in center of rolling sheetand spread sample into a flat circle about 2.0 cm deep as shown inFigure 2.

9. Transfer about 200 g of sample to a 250 mL airtight, widemouth containerwith a scoop such as shown in Figure 3. Scoop carefully from thecircumference toward the center, keeping the scoop edge next to the sheet.Take portions at equal intervals of about 5-10 cm around thecircumference of the flattened pile. Use a backing plate as shown inFigure 3.

10. Container must have air space above the sample.

11. Mark sample number on container and copy this on other records asrequired.

12. Clean grinding mill after each use.

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Figure 1. Riffle With Cutoff Gate and Two Pans.

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Figure 3. Technique for Subsampling of Ground Sample.

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Total NitrogenTotal NitrogenModified Comprehensive Method

ScopeScopeThis method determines the total nitrogen content of any fertilizer.

ApparatusApparatus1. Kjeldahl digestion and distillation units.

2. Kjeldahl flask, 800 mL.

3. Ordinary labware.

ReagentsReagents1. Sulfuric acid, 0.5 N H2SO4 (see Appendix A).

2. Sodium hydroxide, 0.25 N NaOH (see Appendix A).

3. Methyl red indicator solution. Dissolve 1.0 g methyl red in 200 mL alcohol.

4. Copper sulfate, CuSO4 or CuSO4•5H2O.

5. Potassium sulfate, K2SO4.

6. Sodium hydroxide solution, 45% NaOH. Dissolve 450 g of NaOH in H2O,cool, and dilute to 1 L.

7. Boiling stones, alundum or pumice, 1.5-2.5 mm.

8. Chromium metal, powder, of particle size not greater than 250 nm.

9. Sulfuric acid, H2SO4.

10. Sulfuric acid, 1 + 1 H2SO4.

11. Hydrochloric acid, HCl.

N-1

1Heat required to bring 250 mL of water at 25oC to a rolling boil in 7-7.5 minutes.

8

ProcedureProcedure1. Weigh 0.2-1.6 g ± 0.5 mg of sample and transfer to a Kjeldahl flask.

Sample must not contain more than 60 mg of nitrate nitrogen. If organicsother than urea or ureaform are present, weigh more than 0.5 g.

2. Add 1.2 g chromium powder and 35 mL H2O. For liquids make totalvolume 35 mL. Let stand for 10 minutes with occasional gentle swirling todissolve all nitrate salts.

3. Add 7 mL HCl and let stand for at least 5 minutes, but not more than10 minutes.

4. Place flask on preheated burner adjusted to a 7-7.5 minute boil test.1 Afterheating 3.5 minutes, remove from heat and let cool.

5. Add 15 g of K2SO4, 0.4 g of CuSO4 or 0.6 g of CuSO4•5H2O, and severalboiling stones.

6. Add 37 mL 1 + 1 H2SO4.

7. Place flask on preheated burner and heat until dense white fumes ofH2SO4 clear the bulb of the flask. Heat another 5-10 minutes. Digestion isnow complete for samples containing ammoniacal, nitrate, and ureanitrogen. For all other samples, swirl flask gently and continue digestionfor 75 minutes.

8. Remove flask from burner. Allow to cool for 8-10 minutes, then swirl flaska few times to prevent solidification of the digest. After further cooling, addabout 300 mL H2O and cool to 25o or below.

9. To a 500 mL Erlenmeyer flask add 1 mL 0.5 N H2SO4 for each 7 mgnitrogen in the sample plus 2 mL in excess. Add 5 drops of methyl redindicator solution and sufficient H2O to cover the lower 15 mm of thedistillate delivery tube. Place the receiving flask under the delivery tube ofthe Kjeldahl distillation unit.

10. Add boiling stones and with the flask tilted in position on the distillationunit add sufficient 45% NaOH solution (at least 45 mL) to make contents

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of Kjeldahl flask strongly alkaline. With the flask tilted, the NaOH willlayer under the acid and not react violently.

11. Connect the flask immediately to the connecting bulb of the distillationunit, swirl the flask so that the contents are mixed well, and heat until 150-200 mL of distillate is collected in the receiver. If indicator changes colorduring distillation, repeat the determination, using either a smaller samplesize or a larger volume of 0.5 N H2SO4.

12. Lower the receiver flask, wash the delivery tube with a few milliliters ofH2O into the collected distillate, and turn off the burner.

13. Titrate with 0.25 N NaOH to the methyl red end point.

14. Make a blank determination using the same reagents, omitting sample.

CalculationCalculation

ReferencesReferences1. Official Methods of Analysis of the Association of Official Analytical

Chemists, 15th Ed., Method 978.02, 1990.

2. Fertilizers — Determination of Total Nitrogen Content — TitrimetricMethod After Distillation, ISO 5315, 1984.

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Ammoniacal NitrogenAmmoniacal NitrogenDistillation-Titrimetric Method

ScopeScopeThis method determines all nitrogen present in the ammoniacal form. It is notapplicable in the presence of urea or its derivatives, cyanamide, or organicnitrogenous compounds.

ApparatusApparatus1. Kjeldahl distillation unit.

2. Kjeldahl flasks, 800 mL.




3. Methyl red indicator solution. Dissolve 1.0 g methyl red in 200 mL alcohol.

4. Sodium hydroxide solution, 45% NaOH. Dissolve 450 g of NaOH in water,cool, and dilute to 1 L.

5. Boiling stones, alundum or pumice, 1.5-2.5 mm.

ProcedureProcedure1. Weigh a sample containing ≤250 mg of ammoniacal nitrogen and transfer

to a Kjeldahl flask.

2. To a 500 mL Erlenmeyer flask add 1 mL of 0.5 N H2SO4 for each 7 mg ofammoniacal nitrogen in the sample plus at least 2 mL excess. Add 5 dropsof methyl red indicator solution and enough H2O to cover the lower15 mm of the distillate delivery tube. Place the flask under the deliverytube on the distillation unit.

3. Add 5 mL of 45% NaOH, several boiling stones, and 300 mL of H2O to theKjeldahl flask and connect immediately to the distillation unit. Swirl tothoroughly mix the contents.

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4. Apply heat and boil until 100-125 mL of distillate is collected in thereceiver flask.

5. Lower the receiver flask and rinse the delivery tube, catching the rinse H2Oin the flask. Turn off the heat.

6. Titrate with 0.25 N NaOH to the methyl red end point.

7. Make a blank determination using the same reagents, omitting sample.


ReferencesReferences1. Fertilizers — Determination of Ammoniacal Nitrogen Content —

Titrimetric Method After Distillation, ISO 5314, 1981.

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Ammoniacal and Nitrate NitrogenAmmoniacal and Nitrate NitrogenDevarda Method

ScopeScopeThe sum of ammoniacal and nitrate nitrogen is determined by this method. Urea,calcium cyanamide, and organic matter must be absent.

ApparatusApparatus1. Kjeldahl distillation unit.

2. Kjeldahl flask, 800 mL.




3. Devarda alloy, 50% Cu, 45% Al, and 5% Zn.


5. Methyl red indicator. Dissolve 1.0 g methyl red in 200 mL alcohol.

ProcedureProcedure1. Weigh 0.5-2.0 g ± 0.5 mg of sample into a Kjeldahl flask and add 300 mL

of H2O and 3.0 g of Devarda alloy.

2. To a 500 mL Erlenmeyer receiving flask add 1 mL 0.5 N H2SO4 for each7 mg nitrogen in the sample plus 2 mL in excess. Add 5 drops of methyl redindicator solution and sufficient H2O to cover the lower 15 mm of thedistillate delivery tube and place the receiving flask under the deliverytube.

3. With the Kjeldahl flask containing the sample in position on the distillationunit, add 5 mL of 45% NaOH by pouring down the side of the flask so thatmixing does not readily occur.

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4. Immediately attach the Kjeldahl flask to the connecting bulb and mix thecontents of the flask by a gentle swirl. Place the flask on the heater andheat slowly. As foaming decreases, increase heat sufficiently to distill250 mL in about 1 hour.

5. Lower the receiving flask, rinse the delivery tube with H2O, and turn offheat.

6. Titrate the excess sulfuric acid with 0.25 N NaOH to the indicator endpoint.

7. Make a blank determination using the same reagents, omitting the sample.


ReferencesReferences 1. Fertilizers — Determination of Ammoniacal amd Nitrate Nitrogen

Content — Modified Devarda Method, ISO/DIS 11792.

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BiuretBiuretSpectrometric Method

ScopeScopeThis method is based on a colored complex formed when copper is added to asolution containing biuret under controlled conditions. The method is applicableto urea and urea solutions only; it cannot be used for mixed fertilizers. Biuret isa nonnutrient, but it is important because it is an undesirable impurity in certainapplications.

ApparatusApparatus 1. Spectrometer — capable of reading at 555 nm and utilizing 2- to 4-cm

cells.

2. Water bath, 30 ± 5o.


ReagentsReagents 1. Sulfuric acid, 0.1 N H2SO4 (see Appendix A).

2. Alkaline tartrate solution. Dissolve 40 g of NaOH in 500 mL of H2O, cool,add 50 g of NaKC4H4O6•4H2O, and dilute to 1 L with H2O. Let stand 1 daybefore use.

3. Copper sulfate solution. Dissolve 15 g of CuSO4•5H2O in CO2-free H2Oand dilute to 1 L.

4. Biuret. To recrystallize, weigh about 10 g of reagent-grade biuret into a2 L beaker, add 1 L of absolute alcohol, and dissolve. Concentrate bygentle heating to reduce volume to about 250 mL. Cool and filter througha fritted glass funnel. Repeat crystallization and dry final product 1 hourat 105o-110o in an oven. Remove from oven, place in a desiccator, and coolto room temperature.

5. Biuret standard solution, 1 mg/mL. Dissolve 1.0000 g ± 0.5 mg ofrecrystallized biuret in CO2-free H2O and dilute to 1 L.

6. Methyl red indicator solution. Dissolve 1.0 g of methyl red in 200 mL ofalcohol.

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ProcedureProcedure1. Weigh ≤10 g of sample containing 30-125 mg of biuret into a 250 mL

beaker. Add 150 mL of 50o H2O and stir for 30 minutes, maintaining thistemperature.

2. Filter into a 250 mL volumetric flask, cool, and dilute to volume.

3. Transfer a 50 mL aliquot of the sample solution to a 100 mL volumetricflask. Also transfer a series of aliquots, 2-50 mL, of the standard biuretsolution to 100 mL volumetric flasks.

4. Adjust the volume to about 50 mL, with CO2-free H2O, and add one dropof methyl red indicator and 0.1 N H2SO4 until pink color is obtained.

5. Add, with swirling, 20 mL of alkaline tartrate solution and then 20 mL ofCuSO4 solution. Dilute to volume, shake 10 seconds, and place in a H2Obath at 30 ± 5o for 15 minutes. Also prepare a reagent blank.

6. Determine absorbance of each solution against the blank at 555 nmutilizing a 2- or 4-cm cell.

7. Plot absorbance versus concentration of biuret and determineconcentration of biuret in sample solution.




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Total PhosphorusTotal PhosphorusPreparation of Sample Solution

ScopeScopeThis method details procedures for the preparation of sample solutions for thedetermination of total phosphate (P2O5) content of fertilizers and fertilizermaterials.

ApparatusApparatus1. Ordinary labware.

ReagentsReagents1. Hydrochloric acid, HCl.

2. Nitric acid, HNO3.

3. Perchloric acid, HClO4.

4. Magnesium nitrate solution. Dissolve 950 g of Mg(NO3)2•6H2O in H2Oand dilute to 1 L.

ProcedureProcedure1. Treat sample by one of the following methods as appropriate:

a. All fertilizers, especially when the spectrometric method is to beapplied: Weigh 1-2 g ± 0.5 mg of sample into a beaker, add20-30 mL HNO3, and boil gently 30-45 minutes. (If the fertilizercontains urea, add 20 mL HCl and boil gently for 20-30 minutes priorto the addition of HNO3.) Cool slightly, add 15-20 mL HClO4, andboil very gently until solution is colorless or very nearly so and densewhite fumes fill the beaker. DDANGER!ANGER! DODO NOTNOT BOILBOIL TOTODDRYNESS!RYNESS! Cool slightly, add 50-100 mL H2O, and boil for5-10 minutes. Cool, transfer to a volumetric flask, dilute to volume,and mix thoroughly. Filter a portion through a dry retentive paper(Whatman No. 42 or equivalent) and complete by method P-5, P-6,or P-7.

b. Materials containing large quantitieslarge quantities of organic matterof organic matter, such ascottonseed meal: Weigh 1.0 g ± 0.5 mg of sample into a 50 mLevaporating dish and add 5 mL of Mg(NO3)2 solution. Evaporate to

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dryness and then ignite to destroy residual organic matter. Cool,dissolve in 5 mL HCl, and transfer to a volumetric flask. Dilute tovolume and mix thoroughly. Filter a portion through a dry retentivepaper (Whatman No. 42 or equivalent) and complete by method P-5or P-6.

c. Materials containing small quantities of organicsmall quantities of organic mattermatter: Weigh1.0 g ± 0.5 mg of sample into a beaker and add 30 mL HNO3 and5 mL HCl. Boil gently until organic matter is destroyed (absence ofreddish-brown fumes). Cool, transfer to a volumetric flask, dilute tovolume, and mix thoroughly. Filter a portion through a dry retentivepaper (Whatman No. 42 or equivalent) and complete by method P-5or P-6.



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Water-Soluble PhosphorusWater-Soluble PhosphorusPreparation of Sample Solution

ScopeScopeThis method specifies a procedure for the preparation of a sample solution forthe determination of water-soluble phosphate (P2O5) in fertilizers and fertilizermaterials.

ApparatusApparatus 1. Filter paper, 9 cm, fine textured (Whatman No. 5 or equivalent).

2. Filtering funnel, 60o, with minimum of 100 mm stem.


ReagentsReagents1. Perchloric acid, HClO4.

ProcedureProcedure1. Weigh 1.0 g ± 0.5 mg of sample and transfer to a 9 cm filter paper fitted

in a funnel.

2. Wash the sample with 10-15 mL portions of H2O until the combinedwashings approximate 225 mL. Add H2O in a fine stream directed aroundentire periphery of filter paper in a circular path, ensuring that the H2Oand solids are thoroughly mixed with each addition. Allow each portion topass through filter before adding more H2O and use suction if washingwould not otherwise be complete in 1 hour. If filtrate is turbid, add 1-2 mLHClO4, dilute to 250 mL, and mix thoroughly.

3. Make final determination of phosphate content by one of the followingmethods:

a. Transfer an aliquot containing ≤25 mg P2O5 to 400 mL beaker, diluteif necessary to 50 mL, add 10 mL 1 + 1 HNO3, and boil gently for10 minutes. Cool, dilute to 100 mL, and proceed with method P-5,beginning with "add 50 mL of quimociac reagent."

b. Transfer an aliquot containing ≤30 mg P2O5 to a 500 mL Erlenmeyerflask, dilute if necessary to 50 mL, add 10 mL 1 + 1 HNO3, and boil

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gently for 10 minutes. Cool, dilute to 100 mL, and proceed withmethod P-6, beginning with "add 20 mL citric acid."

c. Transfer an aliquot of the sample solution containing 2-5 mg of P2O5

to a 100 mL volumetric flask. Proceed with method P-7, beginningwith step 7.

NoteNote: If the sample is suspected to contain nonorthophosphate, it must behydrolyzed by boiling in a dilute (10%) perchloric acid solution prior tothe final measurement of the P2O5 content.


Chemists, 15th Ed., Methods 977.01, 962.03, 962.04, 970.01, 1990.

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Citrate-Insoluble PhosphorusCitrate-Insoluble PhosphorusPreparation of Sample Solution

ScopeScopeThis method separates phosphate (P2O5) that is insoluble in neutral ammoniumcitrate solution and is considered to be unavailable to plants.

ApparatusApparatus 1. Constant temperature bath or oven with shaking apparatus. Shaking action

should be such that dispersion of sample in citrate solution is continuallymaintained and entire inner surface of flask and stopper is continuallybathed with solution.


ReagentsReagents 1. Neutral ammonium citrate solution. Should have a specific gravity of 1.09

at 20o and a pH of 7.0 measured potentiometrically. Dissolve 370.0 gcrystalline citric acid in 1.5 L H2O and nearly neutralize by adding 345 mLNH4OH (28%-29% NH3). If the concentration of NH3 is less than 28%, addcorrespondingly larger volume of NH4OH and dissolve citric acid incorrespondingly smaller volume of H2O. Cool and check pH. Adjust with1 + 7 NH4OH or citric acid solution to pH 7.0 using a pH meter. Dilutesolution, if necessary, to a specific gravity 1.09 at 20o. Store in tightlystoppered bottle. Check pH frequently and readjust to 7.0 if necessary.


3. Hydrochloric acid, HCl.

4. Ammonium nitrate solution, 5% NH4NO3. Dissolve 50.0 g of crystallineNH4NO3 in H2O and dilute to 1 L.

ProcedureProcedure1. After removing water-soluble P2O5, transfer filter and residue within

1 hour to a 250 mL flask containing 100 mL of neutral ammonium citratesolution previously heated to 65o.

2. Stopper flask tightly and shake vigorously until paper is reduced to pulp.Relieve pressure in flask by removing stopper momentarily.

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3. Continuously agitate stoppered flask in constant temperature apparatus at65o for exactly 1 hour.

4. Remove flask from apparatus and immediately filter sample solution asrapidly as possible through a retentive filter paper (Whatman No. 5 orequivalent) using a Buchner funnel with vacuum.

5. Wash paper and residue with H2O heated to 65o until the volume of filtrateis approximately 350 mL, allowing time for thorough draining betweeneach addition of wash H2O. If sample yields a cloudy filtrate, wash with 5%NH4NO3 solution.

6. Prepare the residue for analysis by one of the following methods:

a. Place the filter paper and residue in a porcelain crucible or dish. Drygently and ignite at 600o to destroy all organic matter. Transfer to a250 mL beaker, add 5 mL HClO4, cover with a watch glass, and digestat low temperature for 10 minutes. Dilute to volume in a volumetricflask, mix, and filter a portion through a dry retentive paper(Whatman No. 42 or equivalent).

b. Transfer wet pad and residue to a 250 mL beaker and digest withsuccessive additions of HNO3 until all organic matter is destroyed.Add 5 mL of HClO4 and bring to dense white fumes of HClO4. Cool,transfer to volumetric flask, dilute to volume, and mix. Filter aportion through a dry retentive paper (Whatman No. 42 orequivalent).

7. Make final determination of phosphate content by method P-5, P-6, or P-7.



P-4

22

Direct-Available PhosphorusDirect-Available PhosphorusPreparation of Sample Solution

ScopeScopeThis method is used for the preparation of sample solution containing water-soluble and citrate-soluble phosphate (P2O5). The sum of the two is assumed tobe the phosphate that is available to plants.

ApparatusApparatus1. Constant temperature oven or bath with shaking apparatus. Shaking action

should be such that dispersion of sample in citrate solution is continuouslymaintained and entire inner surface of flask and stopper is continuouslybathed with solution.

2. Filter paper, 9 cm fine textured (Whatman No. 5 or equivalent).

3. Filtering funnel, 60o, with minimum of 100 mm stem.


ReagentsReagents1. Neutral ammonium citrate solution. Should have a specific gravity of 1.09

at 20o and a pH of 7.0 measured potentiometrically. Dissolve 370.0 gcrystalline citric acid in 1.5 L H2O and nearly neutralize by adding 345 mLNH4OH (28%-29% NH3). If the concentration of NH3 is less than 28%, addcorrespondingly larger volume of NH4OH and dissolve citric acid incorrespondingly smaller volume of H2O. Cool and check pH. Adjust with1 + 7 NH4OH or citric acid solution to pH 7.0 using a pH meter. Dilutesolution, if necessary, to a specific gravity 1.09 at 20o. Store in tightlystoppered bottle. Check pH frequently and readjust to 7.0 if necessary.

2. Ternary acid mixture. Add 20 mL of H2SO4 to 100 mL of HNO3, mix, andadd 40 mL HClO4.

3. Modified molybdovanadate reagent. Dissolve 40 g of (NH4)6Mo7O24•4H2O in 400 mL of hot H2O and cool. Dissolve 2 g of NH4VO3 in 250 mLof hot H2O, cool, and add 250 mL of HClO4. Gradually add molybdatesolution to vanadate solution with stirring and dilute to 2 L.

P-4

23

ProcedureProcedure1. Weigh 1.0 g ± 0.5 mg of sample and place on a 9 cm filter paper fitted in

a funnel.

2. Wash the sample with 10-15 mL portions of H2O until the combinedwashings approximate 225 mL. Add H2O in a fine stream directed aroundthe entire periphery of filter paper in a circular path, ensuring that thewater and solids are thoroughly mixed with each addition. Allow eachportion to pass through filter before adding more H2O and use suction ifwashing would not otherwise be complete in 1 hour. Collect all washingsin a 500 mL volumetric flask.

3. Within 1 hour, transfer filter and residue to a 250 mL flask containing100 mL of neutral ammonium citrate solution previously heated to 65o.

4. Stopper flask tightly and shake flask vigorously until paper is reduced topulp. Relieve pressure in flask by removing stopper momentarily.

5. Continuously agitate stoppered flask in a constant temperature apparatusat 65o for exactly 1 hour.

6. Remove flask from apparatus and quantitatively transfer contents to the500 mL volumetric flask containing the water-soluble fraction.

7. Immediately cool to room temperature, dilute to volume, and mixthoroughly.

8. Filter a portion through a dry retentive filter paper (Whatman No. 40 orequivalent).

9. Complete by one of the following methods:

a. Transfer aliquot containing ≤25 mg P2O5 and ≤10 mL of originalneutral ammonium citrate solution to a 400 mL beaker, dilute ifnecessary to 50 mL, and add 10 mL of 1 + 1 HNO3. Boil gently for 10minutes, cool, dilute to 100 mL with H2O, and continue as in methodP-5, beginning with "add 50 mL quimociac reagent."

b. Transfer aliquot containing ≤30 mg P2O5 and ≤10 mL of originalneutral ammonium citrate solution to a 500 mL Erlenmeyer flask,dilute if necessary to 50 mL, and add 10 mL of 1 + 1 HNO3. Boil

P-4

24

gently for 10 minutes, cool, dilute to 100 mL with H2O, and continueas in method P-6, beginning with "add 60 mL quimociac."

c. Transfer a 10 mL aliquot to a 125 mL Erlenmeyer flask and add 5 mLof ternary acid mixture. Swirl, boil gently for 15 minutes, and digestat 150o-200o until clear white salt or colorless solution remains.Evaporate to white fumes and continue heating for 5 minutes. Cool,add 15 mL of H2O, and boil for 5 minutes. Transfer to 100 mLvolumetric flask, dilute to 50 mL, and cool to room temperature. Add20 mL of modified molybdovanadate solution, dilute to volume, andcontinue as in method P-7, beginning with Step 7.



P-5

25

PhosphorusPhosphorusGravimetric Quimociac Method

ScopeScopeThis method determines the orthophosphate content of sample solutionsprepared by methods outlined for total, water-soluble, citrate-insoluble, anddirect-available phosphate (P2O5). The method, based on the precipitation of thephosphate as quinolinium molybdophosphate, is quite tolerant of extraneousions normally present in solutions of fertilizers.

ApparatusApparatus 1. Crucible, Gooch. Coors No. 4 or equivalent.

2. Filter disc, glass fiber, 2.4 cm.

3. Drying oven, adjusted to 250o.

4. Desiccator.


ReagentsReagents 1. Quimociac reagent. Dissolve 70 g of Na2MoO4•2H2O in 150 mL of H2O.

Dissolve 60 g of citric acid in a mixture of 85 mL of HNO3 and 150 mL ofH2O. Cool and gradually add the molybdate solution to the citric-nitricacid mixture, with stirring. Dissolve 5 mL of synthetic quinoline in a mixtureof 35 mL of HNO3 and 100 mL of H2O. Add the quinoline solutiongradually to the molybdate solution, mix, and let stand for 24 hours. Filter,add 280 mL of acetone, dilute to 1 L, and mix thoroughly.

ProcedureProcedure 1. Transfer an aliquot of the sample solution containing ≤25 mg P2O5 to a

400 mL beaker. Dilute to 100 mL with H2O and add 50 mL of quimociacreagent.

2. Cover the beaker with a watch glass, place on a hot plate in a well-ventilated hood, and boil gently for 1 minute.

3. Remove from hot plate and cool to room temperature, stirring 3-4 timesduring cooling.

P-5

26

4. Allow the precipitate to settle and filter through a tared Gooch cruciblefitted with a glass fiber disc previously dried at 250o. After completetransfer, wash the precipitate an additional three times with 15 mL portionsof H2O allowing the precipitate to suck dry between additions.

5. Dry crucible and contents at 250o for 30 minutes, cool in a desiccator, andweigh as [(C9H7N)3H3(PO4•12MoO3)].

6. Determine a blank by carrying all reagents through entire procedure,omitting the sample.


where A = weight of sample precipitate (g). B = weight of blank precipitate (g).

ReferencesReferences 1. Official Methods of Analysis of the Association of Official Analytical


2. Fertilizers — Determination of Phosphorus Content — QuinolinePhosphomolybdate Gravimetric Method, ISO 6598, 1985.

P-6

27

PhosphorusPhosphorusAlkalimetric Quimociac Method

ScopeScopeThis method determines the total orthophosphate content of sample solutionsprepared by methods outlined for total, water-soluble, citrate-insoluble, anddirect-available phosphate (P2O5). It is based on the precipitation of phosphateas quinolinium molybdophosphate.

ApparatusApparatus 1. Ordinary labware.

ReagentsReagents 1. Quimociac. Dissolve 70 g of Na2MoO4•2H2O in 150 mL of H2O. Dissolve

60 g of citric acid in a mixture of 85 mL of HNO3 and 150 mL of H2O. Cooland gradually add the molybdate solution to the citric-nitric acid mixture,with stirring. Dissolve 5 mL of synthetic quinoline in a mixture of 35 mL ofHNO3 and 100 mL of H2O. Add the quinoline solution gradually to themolybdate solution, mix, and let stand for 24 hours. Filter, add 280 mL ofacetone, dilute to 1 L, and mix thoroughly.

2. Mixed indicator. Mix 2.2 mL of 0.1 N NaOH with 0.1 g of thymol blue anddilute to 100 mL with 50% ethanol. Dissolve 0.1 g of phenolphthalein in100 mL of 50% ethanol. Mix 3 volumes of thymol blue solution with2 volumes of phenolphthalein solution.

3. Citric acid, 10%.

4. Sodium hydroxide, 0.3663 N NaOH (1 mL 1 m g P 2 O 5 ) ( s e eAppendix A).

5. Nitric acid, 0.3663 N HNO3 (see Appendix A).

ProcedureProcedure 1. Transfer an aliquot of the sample solution containing ≤30 mg P2O5 and

≤5 mL acid to a 500 mL Erlenmeyer flask.

2. Add 20 mL citric acid, adjust volume to 100 mL, add 60 mL quimociac,cover with watch glass, and place on medium-temperature hot plate.

P-6

28

3. When the solution reaches the boiling point, move to a cooler portion ofthe hot plate and boil gently for 1 minute.

4. Remove from hot plate and allow to cool until flask can be handled withbare hand.

5. Prepare a pulped-paper filter pad on a perforated porcelain diskapproximately 7 mm thick by pouring two or more approximately equalincrements of a water suspension of pulped paper onto the disk andsucking dry between additions.

6. Swirl flask, pour contents on the filter, and wash the flask five times with15 mL portions of H2O, adding the washings to the filter funnel.Immediately after the funnel has emptied, wash down the sides with a15 mL portion of H2O to remove residual acetone which causes excessivelyfast drying and subsequent lump formation if allowed to evaporate.

7. Wash precipitate three additional times with 15 mL portions of H2O,allowing the funnel to drain between additions.

8. Transfer the precipitate and pad to the precipitation flask and break up padwith jet of H2O.

9. Titrate with 0.3663 N NaOH to disappearance of yellow color and add 2-to 5 mL excess.

10. Add 1 mL of mixed indicator and titrate with 0.3663 N HNO3 to gray-blueend point.

11. Determine a blank on all the reagents by the same procedure with a knownquantity (1-2 mg) of P2O5. Use 1+9 dilutions of standard NaOH and HNO3

for the titration and subtract from the experimental titer the theoreticaltiter equivalent to the P2O5 added. Calculate the difference to 0.3663 NNaOH and subtract this blank from the 0.3663 N NaOH used in all sampledeterminations.

P-6

29




P-7

30

PhosphorusPhosphorusSpectrometric Molybdovanadate Method

ScopeScopeThis method determines the total orthophosphate content of sample solutionsprepared by methods outlined for total, water-soluble, citrate-insoluble, anddirect-available phosphate (P2O5). It is based on the intense yellow color of themolybdovanadate phosphate complex and is relatively free of interference.However, extraneous color, soluble silica, and oxides of nitrogen interfere andmust be absent.

ApparatusApparatus 1. Spectrometer with flow-through cell or matched 1-cm cells.


ReagentsReagents 1. Molybdovanadate solution. Dissolve 40 g of (NH4)6Mo7O24•4H2O in

400 mL of hot H2O and cool. Dissolve 2 g of NH4VO3 in 250 mL of hotH2O, cool, and add 450 mL of HClO4. Gradually add the molybdatesolution to the vanadate solution while stirring and dilute to 2 L.

2. Phosphate standard solutions. Dry pure KH2PO4 (52.15% P2O5) for2 hours at 105o. Prepare solutions containing 0.4-1.0 mg P2O5/mL in0.1-mg increments by weighing 0.0767, 0.0959, 0.1151, 0.1342, 0.1534,0.1726, and 0.1918 g of KH2PO4 and diluting each to 100 mL with H2O.Weekly, prepare fresh solutions containing 0.4 and 0.7 mg P2O5/mL.

ProcedureProcedure 1. Transfer 5 mL aliquots of the seven standard phosphate solutions (2-5 mg

P2O5/aliquot) into 100 mL volumetric flasks and add about 45 mL of H2O.Within 5 minutes for entire series, add 20 mL of molybdovanadatesolution, dilute to volume, mix, and let stand 10 minutes.

2. Fill both reference and sample cells with the 2.0 mg P2O5 standardsolution.

3. Set spectrometer to 400 nm and adjust to read 0 absorbance with standardcell. Verify that sample cell reads 0 absorbance ± 0.001.

P-7

31

4. Using the sample cell, determine the absorbance of the other standardswhile the instrument is adjusted to 0 absorbance with the 2.0 mg P2O5

standard.

5. Plot absorbance versus concentration (mg P2O5/100 mL) for eachstandard.

6. Transfer an aliquot of the sample solution containing 2-5 mg of P2O5 to a100 mL volumetric flask.

7. Transfer aliquots of the standard phosphate solutions containing 2.0 and3.5 mg P2O5/aliquot to 100 mL volumetric flasks.

8. Dilute solution in each flask to about 50 mL with H2O. Within 5 minutes forentire group, add 20 mL of molybdovanadate solution, dilute to volume,and mix. Let stand 10 minutes.

9. Using the standard cell filled with the 2.0 mg P2O5 standard, adjust theinstrument to read 0 absorbance. Using the sample cell, determine theabsorbance of the 3.5 mg P2O5 standard. It should agree with the value onthe standard curve.

10. Read absorbance of the sample solution and determine concentration ofP2O5 from the standard curve.


where A = mg P2O5 from curve.

NotesNotes 1. An instrument equipped with a flow-through cell may be substituted for an

instrument with fixed cells.

2. With some types of spectrometers it may be necessary to empty and refillthe reference cell containing the 2.0 mg P2O5 standard after each

P-7

32

measurement in order to avoid errors that might arise from temperaturechanges.



K-1

33

PotassiumPotassiumGravimetric Tetraphenylborate Method

ScopeScopeThis method specifies a procedure for the determination of water-soluble potash(K2O) in all fertilizers.

ApparatusApparatus1. Drying oven, 120 ± 5o.

2. Filter crucibles, sintered glass or porcelain disc, of porosity grade P10 orP16 (pore size 4-16 nm).


ReagentsReagents 1. Sodium tetraphenylborate (STPB) solution, ~15 g/L. Dissolve 7.5 g of

NaB(C6H5)4 in 480 mL of H2O. Add 2 mL of NaOH solution and 20 mL ofMgCl2 solution (100 g/L of MgCl2•6H2O). Stir for 15 minutes and filterthrough a fine-textured filter paper. May be stored in plastic for up to1 month. Filter immediately before use if necessary.

2. Sodium tetraphenylborate wash solution. Dilute 1 volume of the sodiumtetraphenylborate solution with 10 volumes of H2O.

3. EDTA solution. Dissolve 4.0 g of disodium ethylenediaminetetraacetatedihydrate in 100 mL of H2O.

4. Formaldehyde, 30% HCHO. Filter before use if necessary.


6. Phenolphthalein solution. Dissolve 0.5 g of phenolphthalein in 100 mL of95% ethanol.

7. Bromine water, saturated solution.

8. Charcoal, activated (does not absorb or liberate potassium ions).

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34

ProcedureProcedure 1. Accurately weigh 5 g ± 1.0 mg of sample into a 1,000 mL Erlenmeyer

flask. Add 400 mL of H2O, heat to boiling, and boil for 30 minutes.

2. Cool, transfer to a volumetric flask, dilute to volume, and mix well. Filtera portion through a dry filter paper, discarding the first few milliliters.

3. Proceed as in a or b below:

a. Procedure in presence of cyanamide and/or organic materials.

(1) Transfer an aliquot portion of the clear sample solutioncontaining 50-100 mg of K2O to a 250 mL beaker. Add 5 mL ofbromine water and boil until all bromine has been expelledand the volume is <100 mL.

(2) Cool to room temperature, transfer to a 100 mL volumetricflask, and add about 0.5 g of charcoal. Shake vigorously, diluteto volume, and mix well.

(3) Filter the solution through a dry filter paper and transfer 50 mLto a 250 mL beaker.

b. Procedure in the absence of cyanamide and/or organic materials.

(1) Transfer an aliquot of the clear sample solution containing 25-50 mg of K2O to a 250 mL beaker and adjust the volume to50 mL by dilution or evaporation.

4. Add 20 mL of EDTA solution and a few drops (3-5) of phenolphthaleinsolution. Add NaOH solution dropwise until the appearance of a red colorand then add an additional 1 mL.

5. Boil for 15 minutes. Add 10 mL of HCHO solution and, if necessary, addNaOH solution until the red color persists.

6. Cover the beaker with a watch glass and heat for 15 minutes on a steambath. If the solution does not remain red, add a few drops ofphenolphthalein and, if necessary, NaOH solution to restore the red color.

K-1

35

7. Remove the beaker from the steam bath and immediately add, dropwisewhile stirring, 40 mL of the STPB solution (reagent 1).

8. Continue to stir for 1 minute, cool rapidly to below 20o, and allow to standfor 10 minutes.

9. Filter through a tared filter crucible previously dried at 120 ± 5o andcooled in a desiccator. Decant the supernatant liquid through the crucibleand wash the precipitate in the beaker with 40 mL of the wash solution(reagent 2) and decant. Wash with another 40 mL portion of wash solutionand decant.

10. Quantitatively transfer the precipitate to the crucible with about 40 mL ofwash solution and finally wash the precipitate with 5 mL of H2O.

11. Dry the crucible and precipitate at 120 ± 5o for 90 minutes, cool in adesiccator, and weigh.

12. Determine a blank by the same procedure, omitting the sample.


where A = the weight of precipitate from the sample.B = the weight of precipitate from the blank.

ReferencesReferences 1. Fertilizers — Determination of Potassium Content — Potassium

Tetraphenylborate Gravimetric Method, ISO 5318, 1983.

K-2

36

PotassiumPotassiumTitrimetric Tetraphenylborate Method

ScopeScopeThis method specifies a procedure for the determination of potash (K2O) in allfertilizers after extraction with ammonium oxalate solution. The finalmeasurement of the potash concentration is made by the titrimetrictetraphenylborate method.

ApparatusApparatus 1. Microbiuret, 10 mL capacity, graduated in 0.02 mL divisions or smaller.


ReagentsReagents 1. Sodium hydroxide solution, 20% NaOH. Dissolve 20 g of NaOH in 100 mL

of H2O.

2. Formaldehyde, 37% HCHO.

3. Sodium tetraphenylborate (STPB) solution, ~12 g/L. Dissolve 12 g ofNaB(C6H5)4 in 800 mL of H2O. Add 20-25 g of Al(OH)3, stir for10 minutes, and filter. Add 2 mL of 20% NaOH solution to the clearfiltrate, dilute to 1 L, and mix. Let stand 48 hours before standardizing.

Standardization of STPBStandardization of STPBa. Accurately weigh 2.5 g ± 0.5 mg of KH2PO4 (previously dried at 105o

and cooled in a desiccator), dissolve in H2O, add 50 mL of 4%(NH4)2C2O4•H2O solution, and dilute to volume in a 250 mLvolumetric flask.

b. Transfer a 15 mL aliquot of the KH2PO4 solution containing 51.92 mgof K2O to a 100 mL volumetric flask. Add 2 mL of 20% NaOHsolution, 5 mL of 37% HCHO, and 43.0 mL of the STPB solution.

c. Dilute to volume with H2O, mix thoroughly, and, after 10 minutes,filter through a dry filter paper.

K-2

37

d. Transfer a 50 mL aliquot of the filtrate to a 125 mL Erlenmeyer flask,add 6-8 drops of Clayton yellow indicator, and titrate to a pink endpoint with BAC solution.

e. Calculate a factor (F) by the formula:

4. Benzalkonium chloride (BAC) solution. Dilute 38 mL of 17% Zephiranchloride (benzalkonium chloride) solution to 1 L. To determine the ratiobetween the STPB and BAC solutions, transfer 2.00 mL of the STPBsolution to a 125 mL Erlenmeyer flask. Add 20 mL of H2O, 1 mL of 20%NaOH solution, 2.5 mL of 37% HCHO, 1.5 mL of 4% (NH4)2C2O4•H2Osolution, 6-8 drops of Clayton yellow indicator and titrate with BACsolution to the pink end point. Adjust concentration of BAC so that 2.00 mL= 1.00 mL of STPB.

5. Clayton yellow indicator, 0.04%. Dissolve 0.04 g of Clayton yellow (Titanyellow, color index No. 19540) in H2O and dilute to 100 mL.

6. Ammonium oxalate solution, 4%. Dissolve 40 g of (NH4)2C2O4•H2O inH2O and dilute to 1 L.

7. Charcoal, activated (does not absorb or liberate potassium ions).

ProcedureProcedure 1. Weigh 2.5 g ± 1.0 mg of sample (1.25 g if K2O > 50%) into a 400 mL

beaker. Add 125 mL of H2O and 50 mL of 4% (NH4)2C2O4•H2O solution.

2. Boil for 30 minutes (add ~2 g of charcoal prior to boiling if organic matteris known or thought to be present), cool, dilute to 250 mL in a volumetricflask, and mix thoroughly.

3. Filter a portion of the sample solution through a dry filter, transfer a 15 mLaliquot to a 100 mL volumetric flask, and add 2 mL of 20% NaOH solutionand 5 mL of 37% HCHO.

K-2

38

4. Add 1 mL of STPB solution for each 1% K2O in the sample plus 8 mL inexcess.

5. Dilute to volume with H2O, mix thoroughly, and, after 10 minutes, filterthrough a dry filter.

6. Transfer a 50 mL aliquot of the clear filtrate to a 125 mL Erlenmeyer flask,add 6-8 drops of Clayton yellow indicator solution, and titrate with BACsolution to the pink end point using a microbiuret.

PrecautionsPrecautions 1. The STPB solution is relatively stable. Under normal conditions, biweekly

restandardizations are adequate.

2. Do not premix formaldehyde and sodium hydroxide solution and add asa single reagent. These mixtures rapidly lose their ability to complexammonia.


where A = mL STPB solution.B = mL BAC solution.F = factor, mg K2O/mL STPB.



K-3

39

PotassiumPotassiumAtomic Emission Method

ScopeScopeThis method specifies a procedure for the determination of potash (K2O) in allfertilizers after extraction with ammonium oxalate or water. The finalmeasurement of the potash concentration is made utilizing an atomic emissionspectrometer.

ApparatusApparatus 1. Atomic emission spectrometer with capability of reading emission at

766.5 nm using a lean, oxidizing air-acetylene flame.

ReagentsReagents 1. Potassium chloride solution, 1,000 mg K/L. Dissolve 1.9070 g of KCl in

H2O, add 10 mL HCl and dilute to 1 L.

2. Ammonium oxalate solution, 4%. Dissolve 40 g of (NH4)2C2O4•H2O inH2O and dilute to 1 L.

ProcedureProcedure 1. Prepare a solution of the sample by one of the following methods:

a. Weigh 2.5 g ± 1.0 mg of sample into a 400 mL beaker. Add 125 mLof H2O and 50 mL of 4% (NH4)2C2O4•H2O solution. Boil for30 minutes, cool, and dilute to volume in volumetric flask. Mixthoroughly and filter a portion through a dry filter.

b. Weigh 5.0 g ± 1.0 mg of sample into a 1,000 mL Erlenmeyer flask,add 400 mL of H2O, and heat to boiling. Boil for 30 minutes, cool,transfer to a volumetric flask, and dilute to volume. Mix thoroughlyand filter a portion through a dry filter, discarding the first fewmilliliters.

2. Make a dilution of the clear sample solution from 1.a. or 1.b. such that theconcentration of K is ≤10 mg/L and add sufficient hydrochloric acid so thatthe final sample solution contains 1% HCl.

3. Transfer a 25 mL aliquot of the KCl solution (1,000 mg K/L) to a 500 mLvolumetric flask and dilute to volume. Transfer aliquots of 0, 10, 25, and

K-3

40

50 mL of this solution to a series of 250 mL volumetric flasks, add 2.5 mLof HCl to each flask, and dilute to volume. These solutions contain 0, 2, 5,and 10 mg K/L.

4. Set instrumental parameters as directed in instrument manual.

5. Compare sample and standards by reading alternately about three times.

6. Read concentration directly (if instrument has capability) or plot emissionversus concentration of potassium.


where V = final volume of sample solution.

ReferencesReferences 1. Fertilizers — Determination of Water-Soluble Potassium Content —

Preparation of the Test Solution, ISO 5317, 1983.

2. Official Methods of Analysis of the Association of Official AnalyticalChemists, 15th Ed., Method 958.02C, 1990.

Ca-1

41

CalciumCalciumPotassium Permanganate Method

ScopeScopeThis method specifies a titrimetric determination of calcium, expressed as CaO,applicable to all mineral fertilizers.

ApparatusApparatus 1. Boiling water bath.

2. Electric hot plate with stirring capability.

3. Glass filter crucibles of porosity P16 (pore size 10-16 nm).

4. Vacuum filter apparatus with glass frit support screen or PTFE (e.g.,Teflon) coated support screen and filter paper of about 50 mm diameter.


ReagentsReagents 1. Hydrochloric acid, HCl.


3. Citric acid solution. Dissolve 300 g of citric acid monohydrate in H2O anddilute to 1 L.

4. Ammonium chloride solution. Dissolve 100 g of NH4Cl in H2O and diluteto 1 L.

5. Bromophenol blue solution. Triturate 0.4 g bromophenol blue in 30 mLof 0.02 N NaOH and dilute to 1 L with H2O.

6. Ammonium oxalate solution (saturated). Slurry approximately 50 g of(NH4)2C2O4•H2O with H2O, transfer to a 1 L flask, dilute to volume, andthoroughly mix. Filter through a glass filter crucible.

7. Ammonium oxalate solution (0.1%). Dissolve 1 g of (NH4)2C2O4•H2O inH2O and dilute to 1 L.

Ca-1

42

8. Ammonia solution. Dilute 400 mL of NH4OH (28%-29% NH3) to 1 L withH2O.

9. Sulfuric acid, H2SO4.

10. Sulfuric acid, 1+1 H2SO4.

11. Potassium permanganate standard solution. Dissolve approximately 3.2 gof KMnO4 in H2O and boil for 20 minutes. Cool, filter through a glass filtercrucible into a light-protected 1 L flask, and dilute to volume. After severaldays filter the solution through a glass filter crucible and standardize usingNa2C2O4 solution.

12. Sodium oxalate solution. Accurately weigh 0.25-0.30 g of Na2C2O4 (driedfor 1 hour at 130o and cooled in a desiccator) into a 250 mL Erlenmeyerflask. Dissolve in approximately 100 mL of H2O and add 30 mL of1+1 H2SO4. Heat in a boiling water bath and immediately titrate with thestandard KMnO4 solution to the first permanent pink color.

ProcedureProcedure 1. Weigh 2.0-3.0 g ± 1.0 mg of sample into a 250 mL beaker. Add 15 mL of

H2O, 30 mL of HCl, and 3 mL of HNO3.

2. Cover beaker with a watch glass and boil, while stirring, for 30 minutes.Replace evaporated H2O.

3. Cool, transfer to a 500 mL volumetric flask, dilute to volume, and mix.

4. Filter a portion through a dry paper filter, discarding the first fewmilliliters.

5. Transfer an aliquot of the filtrate containing 30-80 mg of CaO to a 400 mLbeaker.

6. If necessary, dilute to 100 mL. Add 10 mL of citric acid solution and 5 mLof NH4Cl solution.

Ca-1

43

7. Heat to boiling. Add 10 drops of bromophenol blue indicator and 30 mLof hot saturated (NH4)2C2O4•H2O solution, with stirring.

8. With constant stirring, slowly add ammonia solution until the indicatorchanges color. Place beaker on a boiling water bath and allow to stand for30 minutes.

9. Cool to room temperature, filter under vacuum, and wash the precipitatewith cold (NH4)2C2O4•H2O solution (0.1%) until washings are free ofchloride. (Acidify a portion of washings strongly with nitric acid prior toadding silver to test for chloride.)

10. Wash four times with 10 mL portions of ice-cold H2O, breaking the vacuumbefore each addition of H2O to increase efficiency.

11. Using a pair of tweezers, remove the filter paper from the vacuum filterapparatus and transfer to a 250 mL beaker. Rinse the upper portion of thefilter apparatus with H2O and 10 mL of 1 + 1 H2SO4, adding the washingsto the beaker containing the filter paper.

12. Add 4 mL of H2SO4, dilute to 100 mL with H2O, and heat to 80o.

13. Add 1 mL of KMnO4 solution from a buret and stir until pink colordisappears. Continue titrating with the KMnO4 solution until the pink colorremains stable for about 30 seconds.

14. Determine a blank by following the same procedure, omitting the sample.


where V1 = mL of KMnO4 solution required for sample.V2 = mL of KMnO4 solution required for blank.

ReferencesReferences 1. Fertilizers — Determination of Calcium Content — Titrimetric Method,

ISO/CD 10151-2.

Ca-2

44

CalciumCalciumAtomic Absorption Spectrometric Method

ScopeScopeThis method determines the calcium content of fertilizers by atomic absorptionspectrometry. It is applicable to the full range of calcium found in fertilizers.

NoteNote: Atomic absorption spectrometry is used for the determination of manytrace elements in fertilizers. It can also be applied to the determination of macroquantities of various elements by giving sufficient attention to standards, samples,and instrument operating parameters.

ApparatusApparatus1. Atomic absorption spectrometer with a 10 cm air-acetylene burner

adjusted to a reducing flame (rich, red). A wavelength of 422.7 nm is themost sensitive resonance line for calcium.

NoteNote: Less sensitivity may be obtained by rotating the burner head awayfrom the optical axis of the light beam or by substituting a smaller burnerhead.

2. Hollow cathode lamp for calcium.


ReagentsReagents1. Hydrochloric acid, 1 + 1 HCl.

2. Lanthanum solution, 100 g/L. Weigh 235 g of La2O3 into a 3 L beaker. Add700 mL of H2O and 1,000 mL of 1 + 1 HCl. Stir until dissolved, filter intoa 2 L volumetric flask, and cool to room temperature. Dilute to volumewith H2O and mix thoroughly.

3. Primary calcium standard solution, 500 mg/L. Dissolve 1.2490 g of CaCO3,previously dried at 105o, in 20 mL of 1 + 1 HCl and 50 mL of H2O.Transfer quantitatively to a 1 L volumetric flask, dilute to volume, and mixthoroughly. This solution may be stored safely in a polyethylene bottle forapproximately 1 year.

Ca-2

45

4. Secondary calcium standard solution, 50 mg/L. Transfer 50 mL of theprimary calcium standard solution to a 500 mL volumetric flask and diluteto volume with H2O. This solution may be safely stored in a polyethylenebottle for about 2 months.

5. Working calcium standard solutions, 5 mg/L, 10 mg/L, 15 mg/L, and20 mg/L. Transfer 10 mL, 20 mL, 30 mL, and 40 mL of the secondarycalcium standard solution to four 100 mL volumetric flasks. To each flaskadd 10 mL of the La2O3 solution and dilute to volume with H2O.

ProcedureProcedure1. Weigh 2.5 g ± 1.0 mg of sample into a 250 mL beaker, add 50 mL of 1 + 1

HCl, cover with a watch glass, place on a hot plate, and bring to a boil.

2. Continue boiling for 30 minutes. Replace evaporated H2O.

3. Cool, transfer quantitatively to a 500 mL volumetric flask, and dilute tovolume with H2O.

4. Mix thoroughly and filter through a dry paper.

5. Transfer a 50 mL aliquot of the clear filtrate to a 250 mL volumetric flask,dilute to volume with H2O, and mix thoroughly.

6. Transfer a 10 mL aliquot to a 100 mL volumetric flask, add 10 mL of La2O3

solution, dilute to volume, and mix.

7. Prepare a blank solution in the same manner, omitting the sample.

8. Prepare the atomic absorption spectrometer in accordance with themanufacturer's instructions and allow to warm up until stable operatingconditions are reached.

9. Adjust the spectrometer to zero while aspirating the blank solution. Thenobtain readings for the standard solutions and sample solution alternately,about three times each, without interruptions or changing instrumentsettings. Take each reading after a stable signal is obtained.

10. Average the three readings for each standard solution and the samplesolution. Plot absorbance versus calcium concentration for the fourstandard solutions.

Ca-2

46

11. Determine the concentration of the sample solution from the standardcurve.

NoteNote: If the spectrometer is equipped with a curve corrector, direct digitalreadout, or similar accessory, these systems may be used after appropriateverification.


where V1 = initial sample volume in mL.V2 = second sample volume in mL.V3 = final sample volume in mL.V4 = initial sample aliquot in mL.V5 = final sample aliquot in mL.

When all aliquots and dilutions are followed, then:

ReferencesReferences1. Fertilizers — Determination of Calcium by Atomic Absorption

Spectrometry, ISO/CD 10151.

Mg-1

47

MagnesiumMagnesiumAtomic Absorption Spectrometric Method

ScopeScopeThis method determines the magnesium content of all fertilizers by atomicabsorption spectrometry.

ApparatusApparatus1. Atomic absorption spectrometer with a 10 cm air-acetylene burner

adjusted to an oxidizing flame (lean, blue). A wavelength of 285.2 nm isthe most sensitive resonance line for magnesium.

NoteNote: Less sensitivity may be obtained by rotating the burner head away fromthe optical axis of the light beam or by substituting a 5 cm nitrous oxide burnerhead.

2. Hollow cathode lamp for magnesium.



2. Lanthanum solution, 100 g/L. Weigh 235 g of La2O3 into a 3 L beaker. Add700 mL of H2O and 1,000 mL of 1 + 1 HCl. Stir until dissolved, filter intoa 2 L volumetric flask, and cool to room temperature. Dilute to volumewith H2O and mix thoroughly.

3. Primary magnesium standard solution, 1,000 mg/L. Dissolve 1.0000 g± 0.5 mg of pure magnesium metal (acid washed and dried) in 20 mL of1 + 1 HCl and 50 mL of H2O in a covered 600 mL tall-form beaker.Transfer quantitatively to a 1 L volumetric flask, dilute to volume, and mixthoroughly. This solution may be stored in a polyethylene bottle forapproximately 1 year.

4. Secondary magnesium standard solution, 10 mg/L. Transfer 10 mL ofprimary magnesium standard solution to a 1 L volumetric flask and diluteto volume with H2O. This solution is stable for about 2 months inpolyethylene.

Mg-1

48

5. Working magnesium standard solutions, 0.5 mg/L, 1.0 mg/L, 1.5 mg/L,and 2.0 mg/L. Transfer 5 mL, 10 mL, 15 mL, and 20 mL of the secondarymagnesium standard solution to four 100 mL volumetric flasks. To eachflask add 10 mL of La2O3, dilute to volume with H2O, and mix thoroughly.

ProcedureProcedure1. Transfer a 2.5 g ± 1.0 mg of sample to a 250 mL beaker and add 50 mL of

1 + 1 HCl.

2. Cover with a watch glass, place on a hot plate, and bring to a boil.

3. Continue to boil for 30 minutes. Replace evaporated H2O.

4. Cool the solution, transfer to a 500 mL volumetric flask, and dilute tovolume with H2O.

5. Thoroughly mix and filter a portion through a dry paper, discarding thefirst few milliliters.

6. Transfer a 50 mL aliquot to a 250 mL volumetric flask, dilute to volumewith H2O, and mix thoroughly.

7. Transfer 10 mL to a 100 mL volumetric flask, add 10 mL of La2O3 solution,dilute to volume, and mix.


9. Prepare the atomic absorption spectrometer in accordance with themanufacturer's instructions and allow to warm up until stable operatingconditions are reached.


11. Average the three readings for each standard solution and the samplesolution. Plot absorbance versus magnesium concentration for the fourstandard solutions.

Mg-1

49




where V1 = initial sample volume in mL.V2 = second sample volume in mL.V3 = final sample volume in mL.V4 = first sample aliquot in mL.V5 = second sample aliquot in mL.

When all aliquots and dilutions are followed, then:

ReferencesReferences1. Fertilizers — Determination of Magnesium by Atomic Absorption

Spectroscopy, ISO/CD 10152.

S-1

50

SulfurSulfurGravimetric Barium Sulfate Method

ScopeScopeThis method determines mineral acid-soluble sulfate sulfur in fertilizers.

ApparatusApparatus1. Oven — controlled at 120 ± 5o.

2. Furnace — controlled at 800 ± 50o.

3. Crucible — filter crucible with porcelain disc, porosity grade P10 (pore sizeindex 4 nm to 10 nm).


ReagentsReagents1. Hydrochloric acid, HCl.

2. Barium chloride solution. Dissolve 122 g of BaCl2•2H2O in H2O and diluteto 1 L.

3. Silver nitrate solution. Dissolve 5 g of AgNO3 in H2O and dilute to 1 L.

ProcedureProcedure1. Accurately weigh a sample containing ≤400 mg of SO3 into a 400 mL

beaker.

2. Add 200 mL of H2O and 25 mL of HCl.

3. Heat to boiling, boil for 10 minutes, and cool.

4. Transfer quantitatively to a 250 mL volumetric flask, dilute to volume withH2O, and mix thoroughly.

5. Filter a portion of the sample through a dry filter and transfer 50 mL of theclear filtrate to a 600 mL beaker.

NoteNote: The amount of sample utilized for the precipitation of barium sulfateshould contain 25-85 mg of SO3 and 5 mL of HCl.

S-1

51

6. Dilute to 300 mL with H2O and heat to boiling.

7. With continuous stirring, slowly add 10 mL of BaCl2 solution, cover witha watch glass, and continue boiling for several minutes.

8. Remove from heat and allow the precipitate to settle for a minimum of3 hours (preferably 12-16 hours) at 50o-60o.

9. Filter through a tared filter crucible previously heated at 800o ± 50o andcooled in a desiccator.

10. Decant the clear supernatant liquid and wash the precipitate several timesby decanting with hot H2O (50o-60o).

11. Transfer the precipitate to the crucible with hot H2O and continue washinguntil the washings are free of chloride ions as determined with the AgNO3

solution.

12. Dry the crucible containing the precipitate at 120o ± 5o for 1 hour and thenheat at 800o ± 50o for 30 minutes.

13. Remove from the furnace, cool in a desiccator, and weigh.

NoteNote: Total sulfur may be determined in samples containing non-sulfate sulfurby this method provided that all the sulfur in the sample is first oxidized to thesulfate form.


where A = wt. of crucible and precipitate.B = wt. of crucible.

S-1

52

ReferencesReferences1. Solid Fertilizers — Determination of Mineral Acid-Soluble Sulfate

Content — Gravimetric Method, ISO 10084, 1992.

B-1

53

BoronBoronAzomethine H Spectrometric Method

ScopeScopeThis method determines water-soluble and acid-soluble boron in fertilizers. It issensitive to slight procedural deviations, and care must be exercised in itsapplication.

ApparatusApparatus1. Spectrometer capable of reading absorbance at 420 nm and equipped with

a 1 cm or flow-through cell.

2. Pipet, 100 µL.

3. Erlenmeyer flask, 10 mL.

ReagentsReagents1. Primary boron standard solution, 100 mg/L. Dissolve 0.5716 g of H3BO3

in H2O and dilute to 1 L. Mix thoroughly and transfer to plastic bottle.

2. Working boron standard solutions, 0 mg/L, 5 mg/L, 10 mg/L, 15 mg/L,20 mg/L, 25 mg/L, 30 mg/L, and 45 mg/L. Pipet 0 mL, 5 mL, 10 mL,15 mL, 20 mL, 30 mL, and 45 mL of primary boron standard solution intoseparate 100 mL volumetric flasks and dilute to volume with 1% HCl. Mixthoroughly and transfer to plastic bottles. Solutions are stable.

3. Azomethine H solution. Dissolve 0.9 g azomethine H and 2.0 g of ascorbicacid in 100 mL of H2O. Store in refrigerator and discard after 14 days.

4. Buffer-masking solution. Dissolve 140 g of CH3COONH4, 10 g ofCH3COOK, 4 g of nitrilotriacetic acid, disodium salt, 10 g of (ethylene-dinitrilo) tetraacetic acid, and 350 mL of 10% CH3COOH (V/V) in H2Oand dilute to 1 L. Solution is stable.

5. Transfer 35 mL of azomethine H solution and 75 mL of buffer-maskingsolution to a 250 mL volumetric flask and dilute to volume with H2O.Prepare fresh daily.

B-1

54

ProcedureProcedurePreparation of Sample SolutionPreparation of Sample SolutionA. Acid-Soluble Boron

1. Weigh 2.0 g ± 1.0 mg of sample into a 100 mL volumetric flask and add30 mL of H2O and 10 mL of HCl.

2. Stopper and shake for 15 minutes.

3. Dilute to volume with H2O, mix, and filter immediately through a drypaper into a plastic bottle. Dilute, if necessary, so that final solution forcolor measurement falls within the boron concentration range of thestandard curve.

B. Water-Soluble Boron1. Weigh 2.0 g ± 1.0 mg of sample into a 250 mL beaker, add 50 mL of

H2O, and boil for 10 minutes.

2. While hot, filter through a retentive paper (Whatman No. 40 orequivalent) into a 100 mL volumetric flask.

3. Wash paper and residue with hot, boiled water until total volume isabout 95 mL.

4. Cool, add 1.0 mL of HCl, dilute to volume with H2O, and mix thoroughly.

5. Transfer to a plastic bottle immediately.

6. Dilute, if necessary, so that final solution for color measurement fallswithin the boron concentration range of the standard curve.

DeterminationDetermination1. Transfer 100 µL aliquots of 0 mg/L, 5 mg/L, 10 mg/L, 15 mg/L, 20 mg/L,

25 mg/L, 30 mg/L, and 45 mg/L working boron standard solutions anda 100 µL aliquot of the sample solution to separate 10 mL Erlenmeyerflasks.

2. Add 5.0 mL of color-developing reagent by automatic pipet dispenser (ifunavailable use 5 mL pipet), mix thoroughly, and let stand for 1 hour atroom temperature.

B-1

55

3. Read absorbance at 420 nm against H2O and correct for reagent blank(0 mg/L standard).

4. Plot absorbance versus boron concentration of standards.

5. Determine concentration of boron in sample from the standard curve.


where F = sample dilution factor.


Chemists, 15th Edition, Method 982.01, 1990.

Cl-1

56

ChlorideChlorideTitrimetric Silver Nitrate Method

ScopeScopeThis method determines water-soluble chloride in all fertilizers.

ApparatusApparatus1. Ordinary labware.

ReagentsReagents1. Silver nitrate solution. Dissolve 5 g of AgNO3 in H2O and dilute to 1 L.

Standardize against pure, dry NaCl and adjust so that 1 mL of solution =1 mg of Cl.

2. Potassium chromate indicator solution. Dissolve 5 g of K2CrO4 in H2O anddilute to 1 L.

3. Sodium bicarbonate, NaHCO3.

ProcedureProcedure1. Place 2.5 g ± 1.0 mg of sample on 11 cm filter paper and wash with

successive portions of boiling water into a 250 mL volumetric flask.

2. Continue washing until total volume is about 250 mL.

3. Cool, dilute to volume with H2O, and mix thoroughly.

4. Transfer an aliquot containing between 10 mg and 40 mg of Cl to a 250 mLErlenmeyer flask and adjust volume to about 50 mL.

5. Add 50 mL of H2O to a 250 mL Erlenmeyer flask to be used as a blank.

6. Add 1 mL of K2CrO4 indicator solution to the blank and sample.

7. Titrate the blank solution with the standard AgNO3 solution until areddish-brown color persists.

8. Titrate the sample solution in the same manner to the same reddish-brownend point.

Cl-1

57


where A = mL AgNO3 required for sample. B = mL AgNO3 required for blank.

Note: Store the AgNO3 solution in a glass-stoppered bottle away from light.



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58

CobaltCobaltAtomic Absorption Spectrometric Method

ScopeScopeThis method determines the total cobalt content of all fertilizers by atomicabsorption spectrometry.

ApparatusApparatus1. Atomic absorption spectrometer with an air-acetylene burner adjusted to

an oxidizing (lean, blue) flame. A wavelength of 240.7 nm is the mostsensitive resonance line for cobalt. Less sensitivity may be obtained byrotating the burner head or selecting an alternate resonance line.

2. Hollow cathode lamp for cobalt.





4. Primary cobalt standard solution, 1,0000 mg/L. Dissolve 1.0000 g± 0.5 mg of cobalt metal or 4.0530 g of CoCl2•6H2O in 20 mL of 1 + 1HCl. Cool, dilute to volume in a 1 L volumetric flask, and mix thoroughly.

5. Secondary cobalt standard solution, 25 mg/L. Transfer a 25 mL aliquot ofthe primary cobalt standard solution to a 1 L volumetric flask, dilute tovolume with H2O, and mix thoroughly.

6. Working cobalt standard solutions, 2.5 mg/L, 5.0 mg/L, 7.5 mg/L, and10 mg/L. Transfer 10 mL, 20 mL, 30 mL, and 40 mL of the secondarycobalt standard solution to four 100 mL volumetric flasks, adjust theacidity of each to approximately equal that of the sample, dilute to volumewith H2O, and mix thoroughly.

Co-1

59

ProcedureProcedureSample PreparationSample PreparationA. Hydrochloric Acid Dissolution Method

1. Accurately weigh 2.5 g ± 1.0 mg of sample into a 250 mL beaker, add50 mL of 1 + 1 HCl, and cover with a watch glass.

2. Heat to boiling and continue to boil until volume is reduced to about25 mL.

3. Dilute to about 100 mL with H2O and bring to a boil.

4. Cool, transfer to a 500 mL volumetric flask, and dilute to volume withH2O.

5. Mix thoroughly and allow to stand until clear or filter a portion througha dry retentive paper.

6. Transfer a 25 mL aliquot to a 250 mL volumetric flask, dilute to volume,and mix thoroughly.


8. Continue under determination.

B. Nitric-Perchloric Acid Dissolution Method1. Accurately weigh 2.5 g ± 1.0 mg of sample into a 250 mL beaker and add

10 mL of H2O and 25-30 mL of HNO3. Boil until brown fumes cease andvolume is reduced to about 15 mL.

2. Add 10 mL of HNO3 and 20 mL of HClO4 (see safety note), place on hotplate, and boil until dense white fumes of HClO4 fill the beaker.

3. Cool, dilute to about 100 mL with H2O, and bring to a boil.



Co-1

60




DeterminationDetermination1. Prepare the atomic absorption spectrometer in accordance with the

manufacturer's instructions and allow to warm up until stable operatingconditions are reached.

2. Adjust the spectrometer to zero while aspirating the blank solution.Then obtain readings for the standard solutions and sample solutionalternately, about three times each, without interruptions or changinginstrument settings. Take each reading after a stable signal is obtained.

3. Average the three readings for each standard solution and the samplesolution. Plot absorbance versus cobalt concentration for the fourstandard solutions.

4. Determine the concentration of cobalt in the sample solution from thestandard curve.



where V1 = initial sample volume in mL.V2 = final sample volume in mL.V3 = sample aliquot volume in mL.

* If a fertilizer fails to meet guarantee for this element, the determination shouldbe repeated using the nitric-perchloric acid dissolution method (B). Also, thismethod should be applied if the fertilizer is known to contain a significant

Co-1

61

quantity of organic matter. Otherwise, the hydrochloric acid dissolution method(A) should be used on a regular basis.

Cu-1

62

CopperCopperAtomic Absorption Spectrometric Method

ScopeScopeThis method determines copper in all fertilizers by atomic absorptionspectrometry.

ApparatusApparatus1. Atomic absorption spectrometer with an air-acetylene burner adjusted to

an oxidizing (lean, blue) flame. A wavelength of 324.7 nm is the mostsensitive resonance line for copper. Less sensitivity may be obtained byrotating the burner head or selecting an alternate resonance line.

2. Hollow cathode lamp for copper.





4. Primary copper standard solution, 1,000 mg/L. Dissolve 1.0000 g ± 0.5 mgof copper metal in a minimum of HNO3. Add 5 mL of HCl and evaporateto near dryness. Add 40 mL of 1 + 1 HCl, cool, and transfer to a 1 L flask.Dilute to volume with H2O and mix thoroughly.

5. Secondary copper standard solution, 10 mg/L. Transfer 10 mL of primarycopper standard solution to a 1 L volumetric flask, dilute to volume withH2O, and mix thoroughly.

6. Working copper standard solutions, 0.5 mg/L, 2.0 mg/L, 3.5 mg/L, and5.0 mg/L. Transfer 5 mL, 20 mL, 35 mL, and 50 mL of the secondarycopper standard solution to four 100 mL volumetric flasks, adjust theacidity to be approximately equal to that of the sample, dilute to volumewith H2O, and mix thoroughly.

Cu-1

63












2. Add 10 mL of HNO3 and 20 mL of HClO4 (see safety note), place on hotplate, and boil until dense white fumes of perchloric acid fill the beaker.




Cu-1

64






2. Adjust the spectrometer to zero while aspirating the blank solution. Thenobtain readings for the standard solutions and sample solutionalternately, about three times each, without interruptions or changinginstrument settings. Take each reading after a stable signal is obtained.

3. Average the three readings for each standard solution and the samplesolution. Plot absorbance versus copper concentration for the fourstandard solutions.


NoteNote: If the spectrometer is equipped with a curve corrector, direct digitalreadout, or similar accessory, use these systems after appropriate verification.



*If a fertilizer fails to meet guarantee for this element, the determinationshould be repeated using the nitric-perchloric acid dissolution method (B).Also, this method should be applied if the fertilizer is known to contain asignificant quantity of organic matter. Otherwise, the hydrochloric aciddissolution method (A) should be used on a regular basis.

Cu-1

65



Fe-1

66

IronIronAtomic Absorption Spectrometric Method

ScopeScopeThis method determines total iron in all fertilizers by atomic absorptionspectrometry.

ApparatusApparatus1. Atomic absorption spectrometer with air-acetylene burner adjusted to an

oxidizing flame (lean, blue). A wavelength of 248.3 nm is the mostsensitive resonance line for iron.

2. Hollow cathode lamp for iron.





4. Primary iron standard solution, 1,000 mg/L. Dissolve 1.0000 g ± 0.5 mgof iron wire in 15 mL of HCl with the aid of a few drops of HNO3. Transferto a 1 L volumetric flask and dilute to volume with H2O.

5. Secondary iron standard solution, 25 mg/L. Transfer a 25 mL aliquot of theprimary iron standard solution to a 1 L volumetric flask, dilute to volumewith H2O, and mix thoroughly.

6. Working iron standard solutions, 2.5 mg/L, 5.0 mg/L, 7.5 mg/L, and10.0 mg/L. Transfer 10 mL, 20 mL, 30 mL, and 40 mL of the secondaryiron standard solution to four 100 mL volumetric flasks, adjust the acidityof each to approximately equal that of the sample, dilute to volume withH2O, and mix thoroughly.

Fe-1

67
















Fe-1

68







3. Average the three readings for each standard solution and the samplesolution. Plot absorbance versus iron concentration for the four standardsolutions.


Note: If the spectrometer is equipped with a curve corrector, direct digitalreadout, or similar accessory, use these systems after appropriate verification.



* If a fertilizer fails to meet guarantee for this element, the determinationshould be repeated using the nitric-perchloric acid dissolution method (B).Also, this method should be applied if the fertilizer is known to contain asignificant quantity of organic matter. Otherwise, the hydrochloric aciddissolution method (A) should be used on a regular basis.

Fe-1

69



Mn-1

70

ManganeseManganeseAtomic Absorption Spectrometric Method

ScopeScopeThis method determines total manganese in all fertilizer by atomic absorptionspectrometry.


oxidizing (lean, blue) flame. A wavelength of 279.5 nm is the mostsensitive resonance line for manganese. Less sensitivity may be obtained byrotating the burner head or selecting an alternate resonance line.

2. Hollow cathode lamp for manganese.





4. Primary manganese standard solution, 1,000 mg/L. Dissolve 1.5825 g± 0.5 mg of MnO2 in about 30 mL of 1 + 1 HCl and boil to volatilizechlorine. Cool, dilute to 1 L with H2O, and mix thoroughly. This solutionmay be stored in a polyethylene bottle for about 1 year.

5. Secondary manganese standard solution, 25 mg/L. Transfer a 25 mLaliquot of the primary manganese standard solution to a 1 L volumetricflask, dilute to volume with H2O, and mix thoroughly.

6. Working manganese standard solutions, 2.5 mg/L, 5.0 mg/L, 7.5 mg/L, and10 mg/L. Transfer 10 mL, 20 mL, 30 mL, and 40 mL of the secondarymanganese standard solution to four 100 mL volumetric flasks, adjust theacidity of each to approximately equal that of the sample, dilute to volumewith H2O, and mix thoroughly.

Mn-1

71
















Mn-1

72







3. Average the three readings for each standard solution and the samplesolution. Plot absorbance versus manganese concentration for the fourstandard solutions.






Mn-1

73



Na-1

74

SodiumSodiumAtomic Emission Spectrometric Method

ScopeScopeThis method determines sodium in all fertilizers by atomic emissionspectrometry.

ApparatusApparatus1. Atomic emission spectrometer with an air-acetylene flame is recommended.

An emission wavelength of 589.0 nm is the most sensitive resonance linefor sodium. Reduced sensitivity may be obtained by rotating the burnerhead.


ReagentsReagents1. Ammonium oxalate solution. Dissolve 40 g of (NH4)2C2O4•H2O in H2O

and dilute to 1 L.

2. Primary sodium standard solution, 1,000 mg/L. Dissolve 2.5421 g± 0.5 mg of NaCl (previously dried for 2 hours at 105o and cooled in adesiccator) in H2O and dilute to 1 L in a volumetric flask.

3. Secondary sodium standard solution, 10 mg/L. Transfer 10 mL of primarysodium standard solution to a 1 L volumetric flask, dilute to volume withwater, and mix thoroughly.

4. Working sodium standard solutions, 0.5 mg/L, 1.0 mg/L, 1.5 mg/L, and2.0 mg/L. Transfer 5 mL, 10 mL, 15 mL, and 20 mL of the secondarysodium standard solution to four 100 mL volumetric flasks, dilute tovolume with H2O, and mix thoroughly.

ProcedureProcedure1. Weigh 2.5 g ± 1.0 mg of sample into a 400 mL beaker.

2. Add 125 mL of H2O and 50 mL of (NH4)2C2O4•H2O solution.

3. Boil for 30 min, cool, quantitatively transfer to a 500 mL volumetric flask,dilute to volume with H2O, and mix thoroughly.

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75

4. Filter a portion through a dry retentive paper and transfer 10 mL of theclear filtrate to a 250 mL volumetric flask.

5. Dilute to volume with H2O and mix thoroughly.


7. Prepare the spectrometer in accordance with the manufacturer'sinstructions and allow to warm up until stable operating conditions arereached.


9. Average the three readings for each standard solution and the samplesolution. Plot emission versus sodium concentration for the four standardsolutions.







Zn-1

76

ZincZincAtomic Absorption Spectrometric Method

ScopeScopeThis method determines total zinc in all fertilizers utilizing atomic absorptionspectrometry.


oxidizing (lean, blue) flame. A wavelength of 213.9 nm is the mostsensitive resonance line for zinc.

2. Hollow cathode lamp for zinc.





4. Primary zinc standard solution, 1,000 mg/L. Dissolve 1.0000 g ± 0.5 mgof pure zinc metal (acid washed and dried) in about 10 mL of 1 + 1 HCland dilute to 1 L in a volumetric flask. This solution is stable for about1 year when stored in polyethylene.

5. Secondary zinc standard solution, 10 mg/L. Transfer 10 mL of primary zincstandard solution to a 1 L volumetric flask and dilute to volume with H2O.

6. Working zinc standard solutions, 0.5 mg/L, 2.0 mg/L, 3.5 mg/L, and5.0 mg/L. Transfer 5 mL, 20 mL, 35 mL, and 50 mL of the secondary zincstandard solution to four 100 mL volumetric flasks, adjust acidity of eachto be approximately equal to that of the sample, dilute to volume withH2O, and mix thoroughly.

Zn-1

77












2. Add 10 mL of HNO3 and 20 mL of HClO4 (see safety note), place on hotplate, and boil until dense white fumes of perchloric acid fill the beaker.




Zn-1

78







3. Average the three readings for each standard solution and the samplesolution. Plot absorbance versus zinc concentration for the four standardsolutions.


NoteNote: If the spectrometer is equipped with a curve corrector, direct digitalreadout, or similar accessory, use these systems after appropriate verification.




Zn-1

79



H2O-1

80

Free WaterFree WaterVacuum-Desiccation Method

ScopeScopeThis method determines free water in fertilizers by drying under reducedpressure in the presence of a strong desiccant.

ApparatusApparatus1. Vacuum pump, fitted with gauge.

2. Weighing bottle, 70-80 mm in diameter, fitted with a stopper.

3. Vacuum desiccator, with internal diameter about 200 mm.


ReagentsReagents1. Magnesium perchlorate, anhydrous Mg(ClO4)2.

ProcedureProcedure1. Weigh 2.0 g ± 0.5 mg of sample into a tared weighing bottle.

2. Place the unstoppered bottle containing the sample along with the stopperin a vacuum desiccator previously charged with anhydrous magnesiumperchlorate.

3. With the desiccator behind a safety screen, connect to the vacuum pumpand reduce the pressure in the desiccator to 50-55 cm of Mercury (20-25 cm absolute pressure).

4. Dry at this pressure for 16-18 hours, maintaining the temperature at 25o-30o.

5. Allow the pressure in the desiccator to equilibrate with that of theatmosphere by gradually admitting desiccated air.

6. Open the desiccator, quickly stopper the bottle containing the sample, andweigh.

H2O-1

81


where A = wt. of bottle and sample before drying. B = wt. of bottle and sample after drying.

NoteNote: P2O5 or BaO may be substituted for Mg(ClO4)2 as the desiccant.


Chemists, 15th Ed., Method 965.08A, 1990.

Appendix A

Preparation of Standard Solutions

1

Preparation of Standard SolutionsPreparation of Standard SolutionsStandard Acid Solutions

ScopeScopeThis method is for the preparation and standardization of acid solutionsrequired for volumetric titrations.

ApparatusApparatus1. Constant temperature oven.

2. Desiccator containing anhydrous magnesium perchlorate or othersuitable desiccant.

3. Weighing bottles, glass stoppered.


ReagentsReagents1. Acids for standardization — colorless concentrated reagent grade.

2. THAM [Tris(Hydroxy Methyl) amminomethane], Certified analyticalreagent — Dry the primary standard powder for 2 hours at 100o-103o.Store in desiccator.

ProcedureProcedure1. Pour into the storage bottle an amount of water equal to three-fourths

of the volume of the solution to be made.

2. Using an appropriate measuring device, slowly and carefully add to thewater the required volume of concentrated acid (see Calculations,Item 1).

3. Add balance of water required to bring solution to the total volumedesired. Mix thoroughly and allow to cool to room temperature.

2

4. Carefully weigh to the nearest 0.1 mg a suitable amount of the dryTHAM into a 250 mL beaker or suitable flask. Calculate proper amountof THAM to use (see Calculations, Item 2).

5. Add 50 mL CO2-free water to dissolve the THAM.

6. Titrate the THAM solution with the prepared acid solution from a 50 mLburet to a pH of 4.70 using a calibrated pH meter.

7. Read volume of acid solution used to nearest 0.01 mL and calculate thenormality of the prepared solution (see Calculations, Item 3).

CalculationsCalculations1. Volume of concentrated acid required for any desired volume and

normality of standard solution.

Where: N1 = Normality of concentrated acid.N2 = Normality of desired solution.

V = Volume of desired solution in mL.

AcidSpecific Gravity @

25° Assay (%) Normality

HClHNO3

H2SO4

1.191.421.84

387096.6

12.415.836.2

2. Grams THAM needed for standardization of prepared acid solution ofN normality may be estimated:

3

3. Normality of the standardized solution is calculated:

Molecular weight of THAM = 121.136. Each milliequivalent =0.121136 g THAM.

Where: W = weight of THAM used in g. M = mL of acid solution used for the titration.

NotesNotes1. CAUTION: Care must be taken in handling all concentrated acids.

Always add acids to water slowly and cautiously as heat may begenerated. NEVER ADD WATER TO CONCENTRATED ACIDS.

2. If storage bottle is vented to atmosphere, the solution must be protectedby providing storage bottle with suitable guard tube filled with suitabledesiccant.

3. A further check on the normality of the prepared acid solution may bemade by titrating a known volume of standard base (NaOH) ofapproximately the same normality to a pH of 8.6.

Where Va = mL of standard acid used in titration.Vb = mL of standard base titration (25-30 mL).Nb = normality of standard base.

4

Preparation of Standard SolutionsPreparation of Standard SolutionsStandard Base Solutions

ScopeScopeThis method is for the preparation and standardization of sodium hydroxidesolutions required for volumetric titrations.

ApparatusApparatus1. Desiccator containing anhydrous magnesium perchlorate or other

suitable desiccant.

2. Weighing bottles, glass stoppered.

3. Storage bottles, polyethylene, volume as required for solutions to beprepared.


ReagentsReagents1. Sodium hydroxide solution, 50% NaOH, low carbonate. Dissolve

reagent grade NaOH pellets in water. Cool, allow carbonates to settle,and filter through suitable filter paper or fritted-glass funnel usingsuction. Quickly transfer to polyethylene storage bottle and keeptightly closed.

2. Potassium acid phthalate (PAP). Crush (do not grind) a few grams ofPAP to a fineness of approximately 0.25 mm and dry for 1-2 hours at120°. Place in weighing bottle and cool in desiccator.

ProcedureProcedure1. Pour into storage bottle an amount of water equal to one-half of the

volume of solution to be prepared.

2. Measure 50% NaOH with appropriate measuring device and add towater (see Calculations, Item 1).

5

3. Add balance of water required to bring solution to the total volumedesired. Mix thoroughly.

4. Carefully weigh to the nearest 0.1 mg a suitable amount of the dry PAPinto a 250 mL beaker or suitable flask. Calculate proper amount of PAPto use (see Calculations, Item 2).

5. Add 50 mL of CO2-free water to dissolve the PAP.

6. Titrate the PAP solution with the prepared NaOH solution from a 50 mLburet to a pH of 8.6 using a calibrated pH meter.

7. Read the volume of the NaOH solution used to the nearest 0.01 mL andcalculate the normality of the prepared solution (see Calculations,Item 3).

CalculationsCalculations1. Volume 50% NaOH solution required for any desired volume and

normality of standard solution

Where: N = Desired normality of solution. V = Volume of solution in liters.

2. Grams PAP needed for standardization of prepared NaOH solution ofN normality may be estimated:

6

3. Normality of the standardized solution is calculated:

Molecular weight of PAP = 204.23. Each milliequivalent = 0.20423 gPAP.

Where: W = weight of PAP in g. M = mL of NaOH solution used for the titration.

NoteNote: If storage bottle is vented to atmosphere, the solution must be protectedby providing storage bottle with suitable guard tube filled with Ascarite orother suitable CO2-absorbing reagent.

Appendix BAppendix B

Analytical Report FormAnalytical Report Form

Appendix CAppendix C

Laboratory SafetyLaboratory Safety

1

Laboratory SafetyLaboratory Safety

The following guidelines on laboratory safety are generally in keeping with therequirements outlined in the Occupational Health and Safety Act, Title 29, of the U.S.Code of Federal Regulations, part 1910.1450.

Standard Operating Procedures for LaboratoriesStandard Operating Procedures for Laboratories

The following procedures shall be used for all laboratory work with chemicals. MaterialSafety Data Sheets (MSDS) shall be consulted prior to work with any chemical.

A.A. Accidents and SpillsAccidents and Spills

1. EyeEye CContactontact : Promptly flush eyes with water for 15 minutes and seekmedical attention.

2. IngestionIngestion: Seek medical attention immediately.

3. SkinSkin ContactContact: Flush the affected area with water and remove anycontaminated clothing. If symptoms persist after washing, seek medicalattention.

4. CleanupCleanup: Promptly clean spills and properly dispose of wastes utilizingappropriate protective apparel and equipment.

B.B. Avoidance of Routine ExposureAvoidance of Routine Exposure

1. Develop and encourage safe habits; avoid unnecessary exposure tochemicals.

2. Do not smell or taste chemicals. Avoid skin contact,

3. Inspect gloves and test glove boxes before use.

4. Do not allow release of toxic substances into recirculated atmospheres. Allapparatus (vacuum pumps, distillation columns) that discharge hazardouschemicals will be vented into local exhaust devices.

2

C.C. Eating and SmokingEating and Smoking

1. Avoid eating, drinking, gum chewing, use of tobacco products, or applicationof cosmetics in areas where laboratory chemicals are present; wash handsbefore conducting these activities.

2. Avoid storage of food or beverages in refrigerators, glassware, or utensilsthat are also used for laboratory operations. Avoid handling or consumptionof food or beverages in chemical storage areas.

D.D. Equipment and GlasswareEquipment and Glassware

Handle and store laboratory glassware with care to avoid damage; do not usedamaged glassware. Use extra care with Dewar flasks and other evacuated glassapparatus; shield or wrap them to minimize dispersal of chemicals and fragmentsshould implosion or breakage occur. A glass tubing manipulator or holder shouldbe used when inserting glass tubing into stopper. Use equipment only for itsdesigned purpose.

E.E. ExitingExiting

Wash areas of exposed skin thoroughly before leaving the laboratory.

F.F. HorseplayHorseplay

Avoid practical jokes or other behavior that might confuse, startle, or distractanother worker.

G.G. Mouth SuctionMouth Suction

Do not use mouth suction for pipeting or siphoning.

H.H. Personal ApparelPersonal Apparel

Confine long hair and loose clothing. Wear appropriate shoes at all times in thelaboratory; do not wear sandals or perforated shoes. Lab coats or long-sleeveclothing should be worn when practical.

3

I.I. Personal HousekeepingPersonal Housekeeping

Keep the work area clean and uncluttered and keep chemicals and equipmentproperly labeled and stored; clean the work area on completion of an operationor at the end of the day.

J.J. Personal ProtectionPersonal Protection

1. Ensure that appropriate eye protection is worn by all persons, includingvisitors, where chemicals are stored or handled and in all designated areas.

2. Wear appropriate gloves when the potential for contact with hazardousmaterials exists; inspect the gloves before each use, wash them beforeremoval, and replace them periodically. Consult manufacturer'sspecifications to determine appropriate glove material.

3. Use any other protective and emergency apparel and equipment asappropriate. Consult manufacturer's specifications where appropriate.

4. Avoid use of contact lenses in the laboratory.

5. Remove laboratory coats immediately if they become saturated with achemical or otherwise lose their protective property.

K.K. PlanningPlanning

Seek information and advice about hazards; plan appropriate protective andemergency procedures; plan positioning of equipment before beginning any newoperation.

L.L. Unattended OperationsUnattended Operations

Leave lights on and place an appropriate sign on the door. Information on the signshould include the name and phone number of a responsible person in case of anemergency. Provide for containment of hazardous substances in the event offailure of a utility service to an unattended operation.

4

M.M. Use of HoodUse of Hood

1. Use the hood for operations that might result in release of hazardouschemical vapors or dust.

2. As a rule of thumb, use a hood or other local ventilation when working withany volatile substance.

3. Confirm adequate hood performance before use; keep hood sash loweredto or below established safe level except when adjustments within the hoodare being made; keep materials stored in hoods to a minimum and do notallow them to block vents or airflow.

4. Leave the hood ON when it is not in active use if toxic substances are storedin it or if it is uncertain whether adequate general laboratory ventilation willbe maintained when it is OFF.

N.N. VigilanceVigilance

Be alert to unsafe conditions and see that they are corrected when detected.

O.O. Waste DisposalWaste Disposal

1. Ensure that each laboratory operation includes plans and training for wastedisposal.

2. Deposit chemical waste in appropriately labeled receptacles and follow allother waste disposal procedures.

3. Do not discharge to the sewer: concentrated acids or bases; highly toxic,malodorous, or lachrymatory substances; or any substance that mightinterfere with the biological activity of wastewater treatment plants, createfire or explosion hazards, cause structural damage, or obstruct flow.

5

P.P. Working AloneWorking Alone

Avoid working alone in a building; do not perform chemical work alone in thelaboratory. A supervisor or another laboratory worker should maintain periodiccontact throughout the day with any individual who is the sole worker in alaboratory.

Q.Q. Hazard PostingHazard Posting

Any novel chemical or safety hazard will be posted at the entry to eachlaboratory.

Protective Equipment RequirementsProtective Equipment Requirements

A.A. Fume HoodsFume Hoods

1.1. Minimum RequirementsMinimum Requirements

a. Fume hoods shall meet or exceed the limits of 75 cm of hood spaceper person and an airflow of 18 meters per minute minimum. In thecase of hazardous chemical usage, the minimum face velocity shall be30 meters per minute. No areas of stagnant air should be present in aproperly functioning hood.

b. The location of the hood sash at which this face velocity is achievedshall be clearly marked and shall be high enough to permit necessaryactivities to be carried out safely.

c. A device for checking the hood face velocity should be readilyaccessible.

d. Hoods shall be vented to the outside of the laboratory building andshall have appropriate scrubbing and filtering devices, if feasible, tominimize contamination of the outside air. Hood exhausts shall belocated far enough away from building air intakes to prevent fumesfrom entering the laboratory building or other nearby buildings.

6

e. The manual Industrial Ventilation, 20th Ed., American Conference ofGovernmental Industrial Hygienists, Cincinnati, Ohio, U.S.A., 1988,shall be consulted to establish acceptable guidelines.

2.2. UseUse

a. Fume hoods shall be used with the sash at or below the marked safeface velocity setting. No portion of the worker's body except the handsand arms shall be inside a fume hood that contains hazardouschemicals.

b. Use of hoods for chemical storage shall be discouraged. In no caseshall chemicals or labware in the hood impede proper airflow throughthe hood.

c. Hood sashes shall be kept closed to the extent that this is compatiblewith the work in progress.

3.3. MaintenanceMaintenance

a. Yearly appraisals of each hood for face velocity and properfunctioning shall be made by a qualified person. This person shall beresponsible for the marking of the maximum safe sash height.

b. If a problem with face velocity or proper functioning of a hood issuspected, the hood shall be tagged out of use and checked. Until thehood has been recertified as properly functional, it shall not be used.

B.B. Other Protective EquipmentOther Protective Equipment

1.1. Minimum RequirementsMinimum Requirements

a. Appropriate protective apparel, such as aprons or lab coats, gloves,safety glasses or goggles, and face shields, shall be required for allareas where work involving hazardous chemicals is performed.

b. Protective apparel shall be chosen to protect against the expectedchemical and physical hazards. Chemical literature and, if necessary,

7

the manufacturer shall be consulted about the compatibility ofchemicals.

c. Equipment, such as eyewashes, safety showers, fire extinguishers, anda telephone or communication device for emergency use, will berequired for all areas where work involving hazardous chemicals isperformed. The above equipment shall be accessible to the workerwithout the need for passage through any doors.

d. Respiratory equipment appropriate to the exposure shall be madeavailable to the worker and others in the work area as necessary.

e. Self-contained breathing apparatus (SCBA) should be available in thehallways outside the laboratories.

f. Appropriate protective equipment and apparel as well as spill kitsshould be available outside but near the laboratory, for use by trainedpersonnel in case of a spill or accident involving hazardous chemicals.

g. Glove boxes and similar containment devices shall be made availableand used if warranted by the degree of chemical hazard or by thenature of the chemicals in use.

2.2. UseUse

a. Appropriate protective apparel and equipment must be properly usedwhen working with hazardous chemicals. The wearers/users must beinformed about the limitations of such protection.

b. Respiratory equipment may not be used without the required trainingon proper fit, testing, and use. Facial hair that interferes with theperipheral fit of the mask will not be allowed. Also, in some cases, aparticular person will not be able to use a respirator if he/she cannotreceive medical clearance.

8

3.3. MaintenanceMaintenance

a. All apparel and equipment should be inspected prior to andimmediately after each use (excluding eyewashes or showers) by theperson using it. They should be clean and functional. Disposable itemsdesigned for only one use should be marked as used and properlydiscarded immediately after use.

b. Fire extinguishers shall be inspected at least annually for properfunction and be tagged with the inspection date and inspector's name.

c. Eyewashes, safety showers, and SCBAs shall be inspected at leastmonthly by the individual responsible for the lab area where they arelocated. At the same time, the inspection tags on fire extinguishers,showers, and hoods should be checked, as should the availability ofspill kits and similar emergency supplies.

9

ReferencesReferences

A.A. General Laboratory SafetyGeneral Laboratory Safety

1. American Chemical Society. Safety in Academic Chemistry Laboratories, 4thedition, 1985.

2. Fawcett, H. H., and W. S. Wood. Safety and Accident Prevention in ChemicalOperations, 2nd edition, Wiley-Interscience, New York, 1982.

3. Flury, Patricia A. Environmental Health and Safety in the Hospital Laboratory.Charles C. Thomas Publisher, Springfield IL, 1978.

4. Green, Michael E., and Turk, Amos. Safety in Working With Chemicals, MacmillanPublishing Co., NY, 1978.

5. Kaufman, James A. Laboratory Safety Guidelines, Dow Chemical Co., Box 1713,Midland, MI 48640, 1977.

6. National Institutes of Health. NIH Guidelines for the Laboratory Use of ChemicalCarcinogens, NIH Pub. No. 81-2385, GPO, Washington, DC 20402, 1981.

7. National Research Council. Prudent Practices for Disposal of Chemicals FromLaboratories, National Academy Press, Washington, DC, 1983.

8. National Research Council. Prudent Practices for Handling Hazardous Chemicalsin Laboratories, National Academy Press, Washington, DC, 1981.

9. Renfrew, Malcolm, Ed. Safety in the Chemical Laboratory, Vol. IV, J. Chem. Ed.,American Chemical Society, Easlon, PA, 1981.

10. Steere, Normal V., Ed. Safety in the Chemical Laboratory, J. Chem. Ed., AmericanChemical Society, Easlon, PA, 18042, Vol. I, 1967, Vol. II, 1971, Vol. III, 1974.

11. Steere, Norman V. Handbook of Laboratory Safety, the Chemical RubberCompany, Cleveland, OH, 1971.

10

12. Young, Jay A., Ed. Improving Safety in the Chemical Laboratory, John Wiley &Sons, Inc., New York, 1987.

B.B. Hazardous SubstancesHazardous Substances

1. American Conference of Governmental Industrial Hygienists. Threshold LimitValues for Chemical Substances and Physical Agents in the WorkroomEnvironment With Intended Changes, P.O. Box 1937, Cincinnati, OH 45201(latest edition).

2. Annual Report on Carcinogens, National Toxicology Program, U.S. Departmentof Health and Human Services, Public Health Service, U.S. Government PrintingOffice, Washington, DC (latest edition).

3. Best Company. Best Safety Directory, Vols. I and II, Oldwick, NJ, 1981.

4. Bretherick, L. Handbook of Reactive Chemical Hazards, 2nd Edition, Butterworths,London, 1979.

5. Bretherick, L. Hazards in the Chemical Laboratory, 3rd Edition, Royal Society ofChemistry, London, 1986.

6. Code of Federal Regulations, 29 CFR part 1910 subpart Z, U.S. Govt. PrintingOffice, Washington, DC 20402 (latest edition).

7. LARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals toMan, World Health Organization Publications Center, 49 Sheridan Avenue,Albany, New York 12210 (latest editions).

8. NIOSH/OSHA Pocket Guide to Chemical Hazards, NIOSH Pub. No. 85-114, U.S.Government Printing Office, Washington, DC, 1985 (or latest edition).

9. Occupational Health Guidelines, NIOSH/OSHA NIOSH Pub. No. 81-123, U.S.Government Printing Office, Washington, DC, 1981.

10. Patty, F. A. Industrial Hygiene and Toxicology, John Wiley & Sons, Inc., New York,NY (Five Volumes).

11

11. Registry of Toxic Effects of Chemical Substances, U.S. Department of Health andHuman Services, Public Health Service, Centers for Disease Control, NationalInstitute for Occupational Safety and Health, Revised Annually, for sale fromSuperintendent of Documents, U.S. Govt. Printing Office, Washington, DC 20402.

12. The Merck Index: An Encyclopedia of Chemicals and Drugs. Merck and CompanyInc., Rahway, NJ, 1976 (or latest edition).

13. Sax, N. I. Dangerous Properties of Industrial Materials, 5th edition, Van NostrandReinhold, NY, 1979.

14. Sittig, Marshall, Handbook of Toxic and Hazardous Chemicals, NoyesPublications, Park Ridge, NJ, 1981.

C.C. VentilationVentilation

1. American Conference of Governmental Industrial Hygienists Industrial Ventilation,16th edition, Lansing, MI, 1980.

2. American National Standards Institute, Inc. American National StandardsFundamentals Governing the Design and Operation of Local Exhaust SystemsANSI Z 9.2-1979 American National Standards Institute, NY, 1979.

3. Imad, A. P., and Watson, C. L. Ventilation Index: An Easy Way to Decide AboutHazardous Liquids, Professional Safety, pp. 15-18, April 1980.

4. National Fire Protection Association, Fire Protection for Laboratories UsingChemicals NFPA — 45, 1982.

Safety Standard for Laboratories in Health Related Institutions, NFPA, 56c, 1980.

Fire Protection Guide on Hazardous Materials, 7th Edition, 1978.

National Fire Protection Association, Batterymarch Park, Quincy, MA 02269.

5. Scientific Apparatus Makers Association (SAMA), Standard for Laboratory FumeHoods, SAMA LF7-1980, 1101 16th Street, NW, Washington, DC 20036.

12

D.D. Availability of Referenced MaterialAvailability of Referenced Material

1. American National Standards Institute (ANSI), 1430 Broadway, New York, NY10018.

2. American Society for Testing and Materials (ASTM), 1916 Race Street,Philadelphia, PA 19103.

Appendix DAppendix D

Typical Job DescriptionsTypical Job Descriptions

1

Typical Job DescriptionTypical Job Description

TitleTitleLaboratory Technician.

DutiesDutiesThe duties of the employee will include sample preparation, some independentanalyses by standard procedures, and assisting an analytical chemist with hisor her assignment. Analyses performed may be titrimetric, gravimetric, orinstrumental and the types of samples will be fertilizer materials.

In assisting chemists with their assignments, the duties will include:

1. Weighing liquid and solid samples.

2. Digestion of samples by specified procedures.

3. Dilution, filtration, or other handling of sample digests.

4. Titration, weighing of precipitate, or instrument measurement ofanalyte.

5. Calculation of final result with programmable calculator.

6. Checking calculations of chemists or other technicians.

Job RequirementsJob Requirements1. A general knowledge and understanding of the basic principles and

techniques of quantative analysis.

2. Knowledge of proper care and utilization of laboratory equipment,glassware, instrumentation, and reagent chemicals.

3. Knowledge of mathematics associated with analytical chemistry.

4. Ability to accurately follow oral and written instruction.

2

5. Ability to work cooperatively with a team.

Complexity of WorkComplexity of WorkMake decision on planning assignments to complete work in most efficientmanner. Judgments on reasonableness of results are normally left tosupervisor, but apparent problems should be noted and suggested to thesupervisor.

Supervision of OthersSupervision of OthersNone.

Supervisory ControlSupervisory ControlSupervisor gives instructions for assignments. Incumbent proceedsindependently unless problems arise. Work is partially reviewed duringprogress and in detail when completed.

GuidelinesGuidelinesIFDC's Fertilizer Analytical Manual is the guideline to follow for the work in thelaboratory.

Impact of WorkImpact of WorkThe analytical results obtained and reported have a major impact on thefertilizer industry. If errors go undetected and incorrect results are reported, agrave injustice can be done to an individual or company.

ContactsContactsContacts outside the immediate work group are very limited.

Work EnvironmentWork EnvironmentThe position may be exposed to hazardous chemicals and possibly dangerousequipment. All precautions should be taken to ensure compliance with safetyguidelines.

QualificationQualificationSome training at the university level in the field of science and an aptitude towork in a laboratory environment.

3


TitleTitleAnalytical Chemist.

DutiesDutiesPerforms quantitative chemical analysis of fertilizer samples.

Determines appropriate methods of analysis based on requested information.Uses methods available in IFDC's Fertilizer Analytical Manual, adapts existingmethods or searches the chemical literature for methods applicable to theassignment. Evaluates results (statistically if necessary) and reportsobservations and conclusions to supervisor. If warranted, a revised method maybe drafted and submitted to the supervisor.

Determinations performed include the utilization of any methods applicable tofertilizer-related material and for which the necessary instrumentation andequipment are available.

Occasionally provides technical supervision for employees of lower grades.

Job RequirementsJob Requirements1. Detailed knowledge and understanding of basic principles, theories, and

techniques in analytical chemistry, especially as applied to fertilizermethodology.

2. A working knowledge of the principles and theories of the operation ofelectronic, optical, and analytical instrumentation.

3. Knowledge of mathematics associated with analytical chemistry,including probability and statistics.

4. Familiarity with specific problems associated with the analysis offertilizers and related materials.

5. Knowledge of chemical literature pertaining to analytical chemistry offertilizers and related materials.

4

Complexity of WorkComplexity of WorkDetermines whether samples should be reanalyzed after reviewing results.Decision is made after considering the precision and accuracy of thedetermination and the reasonableness of the results when compared withresults for other elements determined on the same sample by other chemistsor analysts. If apparent problems occur during analysis, suggestions may beoffered to the supervisor concerning whether the problems were due to thereagents, standards, apparatus, instrument conditions, or interferences. Makesdecisions on planning assignments to complete work in most efficient manner.

Supervision of OthersSupervision of OthersMay provide technical supervision for analytical chemists with less experienceand technicians when necessary to coordinate and expedite work.

Supervisory ControlSupervisory ControlSupervisor provides general instructions for each assignment. When all or asignificant portion of an assignment is complete, the work is subject to generalreview and approval with regard to work methods and subject to a moredetailed review with regard to conclusion.

GuidelinesGuidelinesIFDC's Fertilizer Analytical Manual is the primary guideline for the work of thelaboratory. Other internationally recognized sources such as AOACInternational and ISO are used when applicable. Chemical literature referencematerial may be used when special problems are encountered.


ContactsContactsContacts are generally internal but may involve external contacts to obtainadditional information regarding samples received.

5

Work EnvironmentWork EnvironmentThis position may be exposed to hazardous chemicals when working in thelaboratory. This position is responsible for ensuring that safety procedures arefollowed when handling hazardous chemicals.

QualificationQualificationBachelor's degree in chemistry or equivalent with 1-2 years of experience inanalytical chemistry.

6


TitleTitleAnalytical Laboratory Supervisor.

DutiesDutiesThis position involves the day-to-day supervision of the Fertilizer AnalyticalLaboratory by providing administrative and technical guidance to all laboratorypersonnel. The duties include but may not be restricted to:

1. Overseeing personnel that receive, record, and prepare fertilizersamples for analysis.

2. Assigning fertilizer samples for analysis and reviewing analyses whencomplete.

3. Reporting results and maintaining complete record of analysis andmethods used.

4. Selecting methods of analysis for all nutrients.

5. Providing training for laboratory staff on new methods andprocedures.

6. Modifying existing methods or developing new ones to provideadditional capability or to upgrade the quality of data produced.

Job RequirementsJob RequirementsThis position requires a detailed knowledge of the basic principles, theories,and techniques in analytical chemistry and the ability to apply these principlesand techniques to the chemical analysis of fertilizers. This job may involve thefollowing:

1. Knowledge and application of the principles, theories, and operation ofanalytical instrumentation, such as optical spectrometers and atomicabsorption and emission spectrometers.

7

2. Knowledge of mathematics associated with analytical chemistry tocomplete the analytical process, calculate final results, and presentfindings.

3. Ability to utilize chemical literature and other sources of technicalinformation to remain abreast of new analytical developments andtechniques.

4. Technical writing ability to prepare reports, technical papers, andmanuals.

5. Ability to plan workload to accomplish maximum efficiency of thelaboratory staff.

6. Skill in maintaining excellent interpersonal relations among alllaboratory personnel.

Complexity of WorkComplexity of WorkThis position involves detailed knowledge of analytical chemistry, mathematics,and analytical instrumentation. This position evaluates current methods anddevelops new or modified methods of analysis when necessary to provideadditional capability or increased quality of data. Innovative methodologiesmay create new opportunities or save money. This position provides technicalguidance to the analytical chemist and helps solve problems not specificallycovered by procedures (e.g., problems relating to safety and environmentalcontamination).

When requested by subordinate, this incumbent will render decision as to thereasonableness of an analytical result and offer advice to determine correctnessof same.

Supervision of OthersSupervision of OthersProvides administration and technical supervision for all employees in theFertilizer Analytical Laboratory.

8

GuidelinesGuidelinesIFDC's Fertilizer Analytical Manual is the primary guideline for the work of thelaboratory. Other internationally recognized sources such as AOACInternational and ISO are used when applicable. Chemical literature referencematerial may be used when special problems are encountered.


ContactsContactsContacts are generally internal but may involve external contacts to obtainadditional information regarding samples received.

Work EnvironmentWork EnvironmentThis position may be exposed to hazardous chemicals when working in thelaboratory. This position is responsible for ensuring that safety procedures arefollowed when handling hazardous chemicals.

QualificationsQualificationsMasters degree in chemistry or equivalent with 3-5 years of experience inanalytical chemistry.