Rt?v.1965

NUCLEARSCIENCESERIES

National Academy of Sciences-National Research Council

Pubtished $3y:

United States Atomic Energ Commission

COMMITTEEON NUCLEARSCIENCE

S.K.Allison,Chairman f?.D. Evans,Vice ChairmanUniversityofChicago Mass.InstituteofTechnology

LewisSlack,SecretaryNationalResearchCouncil

E. C.Anderson BerndKahnLos Alamos Sci.Laboratory TaftSanitaryEngineeringCenter

N. E. Ballou JerryB.Marion

U.S.NavalRadiologicalDefenseLaboratory UniversityofMaryland

MartinJ.BergerNationalBureauofStandards

C.J.BorkowskiOak RidgeNatl.Laboratory

RobertG. CochranA & M CollegeofTexas

HerbertGoldsteinColumbiaUniversity

PaulC.AebersoldAtomicEnergyCommission

R. L.PlatzmanArgonneNationalLaboratory

ErnestC.PollardPennsylvaniaStateUniversity

KatherineWayOak RidgeNationallaboratory

GeorgeW. WetherillUniversityofCalifornia(LosAngeles)

LIAISONMEMBERS

RalphG.AllenAirForceOfficeofScientificReeearch

J.HowardMcMillenNationalScienceFoundation

SUBCOMMITTEEON NAOIOCHEMISTRY

N.E. Ballou,ChairmanU.S.NavalRadiologicalDefenseLaboratory

G. R. ChoppinFloridaStateUniversity

H. M. ClarkRensselaerPolytechnicInstitute

R. M. DiamondLawrenceRadiationLaboratory

W. E. NervikLawrenceRadiationLaboratory

J.M. NielsenGeneralElectricCompany (Richfand)

G.D. O’KelleyOak RidgeNationalLaboratory

R.P.SchumanAtomicEnergyDivisionPhillipsPetroleumCompany (IdahoFalls)

A.W. Fairhall E.P. SteinbergUniversityofWashington ArgonneNationalLaboratory

JeromeHudie D. N. SundermanBrookhavenNationalLaboratory BattelleMemorialInstitute

J.D. Knight J.W. WinchesterLos Alamos ScientificLaboratory MassachusettsInstituteofTechnology

Radiochemistry of Selenium

V. J. Molinski

and

G. W. Leddicotte

Ismed,November1966

Union Crmbide Co@oration

Mining and Metals Division

Research Center

Tuxedo, New Yoyk

Subcommitteeon RadiOchemiStry

NationalAcademy ofSciences— NationalResearch Councfl

PrintedinUSA. Price$1.00.AvailablefromtbeClearinghoussforFederalScientificandTechnicalInfmmaticqNationalBureauofStandards,U. S.DepnrunentofCommerce,Springfield,Virginia22151

FOREWORD

The Subcommitteeon Radiochemistry is one of a number ofsubcommittees working under the Comni.tteeon Nuclear Sciencewithin the National Academy of Sciences - National Researchcouncil. Its members represent government, industrial, anduniversity laboratories in the areas of radlochemistry andnuclear chemistry. Support for the activities of this andother subcommittees of the Committee on Nuclear Science isprovided by a grant from the National Science Foundation.

The subcommittee has concerned itself wi’thpreparation ofpublications, encouraghg and supporting ac%ivlties in nucleareducation, sponsoring symposia on selected current topics inradiochemistry and nuclear chemistry, and investigating specialproblems as they arise. A series of monographs on the radio-chemi.sta?yof?essentiallyall %he elementsand on radiochemicaltechniquesis being published. Initiationand encouragementof publication of articles on nuclear education In %rioussubjec% areas of chemistry have occurred, and development andimprovement of certain education activities (e.g., laboratoryand demonstration experiments with radioactivity] have beenencouraged and assisted. Radioactive Contamination of reagentsand materials has been investigated and specific recommendationsmade.

This series of monographshas resulted from the need forcomprehensivecompilationsof radiochemicaland nuclear chemicalinformation. Each monograph collectsin one volume the pertinentinformationrequiredfor radiochemicalwork with an individualelement or with a specializedtechnique. ‘IkeU. S. Atomic EnergyCommissionhas sponsoredthe printing of the series.

Commentsand suggestionsfor ~her publicationsandactivitiesof value to persons working with radioactivityarewelccmedby the Subcommittee.

N. E. lhllOU, ClwuknanSubcommitteeon Mdiochemistry

iii

INTRODUCTION

This monograph on the radiochemistmy of selenium is oneseries covering %he rad%ochemis%ry of essentially all the

elements. It Ls a revised and expanded version of an earliermonograph. In it are included reviews of nuclear and chemicalproperties of selenium, discussionsof methods of sample disso-lution and of separationreactions,descriptionsof couutingtechniques,and a compilationof radiochemicalseparationprocedures~or seleniumas found in the literature.

As new informationaccumulateson chemicaland nuclearpropertiesof seleniumand on separationand measurementtech-niques, considerationwill be given to further revision OI?thismonograph. Consequently as additional information hcomesavailable in Ixsthpublished and unpublished form, readers areencouraged to bring it.to the a’thent%onof the author forpossible inclusion i.nfuture editions of %his monograph.

iv

CONTENTS

I.

II.

III.

rv.

v.

VI.

GENERAL REIFHENCESON THEOF SEMNTO’M . . . . . . .

INORMNIC Am M’?ALY!HCALCHEMISTRY. . . . . . . . . . . . . . . . . . . . . 1

GENERAL REFERENCESCONTAININGINI’ORMK!ZONON THE RAIIBCHEMISTRYOF SELENIUM . . . . . . . . . . . . . . . . . . . . ...2

TAELEOF ISOT~S OF SELENIUM . . . . . . . . . . . . . . . . ...2

IE4TURES OF SELENIUM CHEKK3TRYOF CKCEF INTEREST !IUTHE

1.

2.

3.

4.

5.

6.

7.

8.

9.

RADIOCHEMIST.

INE30DUCTION

THE NmrALIrc

m Oxmzs .

. . . . . . . . . . . . . . . . . . . . . . . . . 6

. . . . . . . . . . . . . . . . . . . . . . . . . 6

SANE . . . . . . . . . . . . . . . . . . . ...6

. . . . . . . . . . . . . . . . . . . . . . . . . 6

0= DATZONSTA3XS . . . . . . . . . . . . . . . . . . ... . . . 8

Sacs.. . . . . . . . . . . . . . . . . . . . . . . . . . .

COMPLEX IONS . . . . . . . . . . . . . . . . . . . . . . . .

cEEtuTEs. . . . . . . . . . . . . . . . . . . . . . . . . .

voLAmLEcoMPoLmnx. . . . . . . . . . . . . . . . . . . . .

PRINCIPALANALYTICALM3THOIJ5. . . . . . . . . . . . . . . .

SELENIUMSEPAFWIONREAC!ITONS . . . . . . . . . . . . . . . . . .

1. SEPARATIONEYPRECIPITJWCON. . . . . . . . . . . . . . . . .

2. SEPAEtATZONBY SOLVENTEXZ’RACTTON. . . . . . . . . . . . . .

3. SEPARMZONBYVOLATILITY. . . . . . . . . . . . . . . . . .

4. ELECI’ROLYTICSEE’ARATION.. . . . . . . . . . . . . . . . . .

5. SEFAMTIONBY IONEXCHKNGE.HHCNS. . . . . . . . . . . . . .

6. SEPARATIONEY PAPER CHROMATOGFWWY . . . . . . . . . . . . .

DISSOLUTIONOF SAMPLES CON’IMININGFZLR%WM. . . . . . . . . . . .

1. MEmsmonms. . . . . . . . . . . . . . . . . . . . . .

2. SALTS. . . . . . . . . . . . . . . . . . . . . . . . . . . .

3. oFm. . . . . . . . . . . . . . . . . . . . . . . . . . . .

4. BIOCHEMICALSAMPLES. . . . . . . . . . . . . . . . . . . . .

5. 0-. . . . . . . . . - . .. . .. . . . . . . . . . ..

v

8

10

10

U

J-1

32

12

u16

16

16

17

17

18

18

18

18

18

VII.

VIII.

lx

x.

Xt.

HKZANXAND PRWAU1210NS. . . . . . . . . . . . . . . . . . . . .

co~TEcHNIms. . . . . . . . . . . . . . . . . . . . . . ●

SEPARATIONPROCEIY.JRESlWR SELEWOM . . . . . . . . . . . . . . . .

INIJEXOF SEPARATIONPROCEDURES. . . . . . . . . . . . . . . . . .

KEFEKENCES. . . . . . . . . . . . . . . . . : . . . . . . . . . .

LIST OF TABLES

I. TABLE OF TEE ISOTOPES OF SELEWUM. . . . . . . . . . . . . . . .

11. CHEMICALANDPSYSICAL PROPERTIESOF ~ . . . . . . . . . . .

III . VOLUBILITY OF SFLENIUMCOMPOUNES. . . . . . . . . . . . . . . . .

Iv. SOLWENT EXCRACTTON SYSTEMS FOR SELENTW . . . . . . . . . . . . .

v. CALCULATEDWECIFTC SATURATIONMZCTVITICESFOR SELIWUM RADIONUCIJXEWPRODUCED BYT!HERMALNEUTRON CKPrUR3. . . . . . . . . . . . . . . . . . . . .

LIST OF FIGURES

1. PARTIAL CHMKCOFTHENUCLIEES SHOWING~ . . . . . . . . . .

2. GAMMA-RAY SPECTRUMOF 7.1-HOUR Sea= . . . . . . . . . . . . . . .

3. GAMMA-FWiSPECITIUMOFl.21-D.&iSe75. . . . . . . . . . . . . . . .

4. GAMMA-RAYSPECTRUMOF 17.5-SEC Se- . . . . . . . . . . . . . . .

5. GAbWA-RM SPE~OF56.&MIN Seam . . . . . . . . . . . . . . .

6. Gw-MsPEcIcurJd oF25-~N Se- . . . . . . . . . . . . . . . .

I-0

19

26

27

46

.3

.7

9

14

20

.5

21

22

23

24

25

vi

Radiochemistry of Selenium

1.

2.

3.

5.

6.

7.

8.

V. J. Molineki

and

G. W. Leddicotte

Union Cmbide Corporation

Mining and Metals Dim’sion

Research Center

Tuxedo, New York

r. GENERALREFERENCESOH INORGANICAND ANALYTICcBIM13TRYOF SELEMIUM

J. W. Keller, A C rehensiveT!reatiseon Inor anic and Theoretical(Lon~% Green and Co., Inc., New fork, 1960), VO1. x,

=2.

W. F. Hlllebrand,G. E. F. LundeU, H. A. Bfi@t, ~d J. I. ~f~,APPlied Inorganic Analysis (JohnWiley and Sons, Inc., New York,1955), Chapt. 19, p. 327-338.

W. R. Schoeller end A. R. Powell, The Analysisof .~,n~ralsand Oresof the Rarer Elements (Hsf’nerPublishingCompany,New York, 1955)~Chapt.XIX, p. 8-254.

Robert C. Brasted, ComprehensiveInorganicChemlst~, Sulfux,Selenium,TelluriuuI,Polonium and O~g en (D. Van Nostrand Co., Inc.,Princeton,New Jersey, 1%1 ).

H. Remy, Treatise on InorganicChemlst~ (Elsevier,Amsterdam,1956),Vol. I, p. 741-752.

J. ~einberg, W. J. Argersinger,and E. Griswold,InorUanic Chemistry

(Heath, Boston, 1960), P. 434-455.

C, L. Wilson and D. W. Wilson, Comprehenslve Analytical ChemistryElsevier, Amaterdmz, 1959).

G. Chariot and D. Bezier, @antltatlve Inorganic ATIalysis (John Wileyand Sons, Inc., New York, 1957).

1

9.

10.

11.

1.

2.

3.

4.

5.

6.

N. V. Sidgwick, The Cheml.cslElements and Their Cmp2uudB (UniversityPress, oxford, 1951) .

B. S. HopkinB, Chapters in the ChemiEtryof the Less FamiliarElements(StipesPublishingCo., Illinois,1939), Chapt. 19.

Selenium amd Tellurium Abstracts,prepared for the Selenium-TelJ.uriumDevelopmentAssociation,Inc. by BattelleMemorial Institute,1959-1964.

II. CXNEML FEIERENCESCONTAININGINFORMAITOIVON THE RADIOCHSTRY OF SELENIUM

w. w.

G. W.

G. W,

H. L.

Meinke, “Nucleonics”,hal. Chein.~, 104R (1960).

Leddlcotte,“NucleonIce”,Anal, Chem.~, 143R (1962).

Leddicotte,“Nucleonlcs”,Anal. them.~, 419R (lg64).

Finstin and J, Miskel, “RadiochemicalSeparationTechniques”,hnual Review of Nuclear Sciencej, 269 (1955);

H. J. M. Bowen and D. Gibbons,RadiosctivationAn- 16 (oxfordUniversityPress, Herd, 1963).

G, W. Leddicotte,cd., “The Radiochemi8tryof Selenium”,Natl. Acad.Sci. - Natl. Research Council Rept. NAS-NS-3030 (1961).

III. TABLE OF THE ISOTUPES OF SEUKHJM

The radioactivenuclldea of seleniumof interestin the radiochemiatryof

8eleniumare given in Table I. This table has been ccunpiledfrcm information

appearingin reporteby Strominger,et al.(1) (2)

and in the Nuclear Data Sheets .

ltLgure1 shows the seleniumportion of the chart of Nuclides(3) includingthe

adjacent elements.

TABLE I

TA8LE OF ISOTOPES OF SELENIUM

Isotopic Type of Pa-title

- * ‘f-life = w

Reactions

se70 &m B+ As75(d,7n)Se70

%71 4.5 m ~+ p: 3.4 &75 (ti, 6n]se717, 0.16

8.4 a EC,~+ 7, 0.046 A.e75(d,5n)Se72

se7m 44m ~+ p: 1.7 AS75(d,k )Se7m;7, 0.88 73m.*74(y, n)Se ,

Se74 (n,2n )Se73m

*73 7,1 h ~:EC ~; 1.29,1.65 As75(d,k) Se7m;y, 0.36,0.066

Se74(y,n)Se7s;

Se74(n,2n)Se7=

~74 0.87$

a?? 5 121 d EC 7, 0.265,0.136 Se74(n,y)Se75;no 9+ 0,28 ,0.405

As75(p,n)Se75;

As75(d,2n)Se75

se7e 9.@

*77 7.584

se- 17.5 s IT Y, 0.162 Se7s(n,7)Se77m;

U fission

~7e 23.52$

*7em3.9 m IT y, 0.096 Se7e (n,7)Se7m;

Se=(n,2n)Se7m;

Br7g(n,p)Se7m;

U fission

3

TABLE I (Continued)

Iflotoplc Type of Particle

= w ‘f-life ~

Ener

H

ReactionsMeV

se7e 6.5x104 y B- P; 0.16 Se7e(n,7)Se7g;

U fission

*SO 49,82$

~Slm 56,8 m IT y, 0.103 SeeO(n,~)Seslm;Slm

Brel(n,p)Se ;

SeeO(d,p)Seam;

U fission

Se.sl 18.2 m B- P; 1.38 Sem(n,7)Seal;

SeeO(d,p)SeaL;

Se=(7,n)See1;

BraL(n,p)Seel;

U fission

.&2 9.1*

@3m 70 s B- ~; 1.5, 3.4 S3m.*=(n,7)Se ,7, 1.01, 2.02,

0,65, 0,35U fission

*B3 25 m B- p; 1.3

Se=(n,7)Se=;7, 0. 5

Se=(d,p)Se=;

U fission andTh fission

3.3 m B- U fission

40 s B- U fission

@6 17 s @- U fission

4

U

FIGURE 1: Partial chart of the nuclides showing selenium.

IV. F!EJ4TUFCZSOF SELENIUM CWSTRYOF CHG3F INTEWISTTO TBE RADIO-ST

1. INTROIXJCTTON

Selenium is found associatedwith sulfur aud sulfides. The usual sources

are the native sulfidessuch ss p~te, chalcop~ite, and zinc blende. Flue

dusts from the roastingof seleniferousores, and the sludge formed in the

lead chambersused In sulftudc-acidmanufacturingprocesses are also highly

enriched sources. Seleniumin these material~ is usually brought into solu-

tion by treatmentwith sulfuric acid and sodiuq nitrate. In this treatment,

It is convertedinto seleniousacid (%SeOS) and selenic acid (H&eOa) and

fintiy precipitatedas elementalseleniumwhen sulfux dioxide is p-seal

through the solution.

Some of the chemlcsland physical propertiesof elementalseleniumare

summarizedin Table 11. Data have been com@led from publicationsby Hopkins(4)

and by Latimer(5).

2. TSE METALLIC STA!171

Selenium,like sulfur, exists in at least three allotropicforms, or

modifications: crystsJllne,metalllc, and amorphous. Cmly the crystalline

and metallic fores have been well ch=acterized. The crystallineform ( a

loose powder ccmposedof at least two varietiesof red, monoclinic,c~stals)

is prep=ed by crystfiization from carbon disulfide,in which it is soluble.

Gray, metallic seleniumis the most stablemodificationand forms hexagonal

crystals. It is relativelyinsolublein carbon dlaulfide,is a good conduc-

tor of electricity,and ia less active chemicallythan the other fores. Gray

seleniumis preparedby heating sny of the other forms at temperaturesof

frcm 200 to 230”c. Amorphousseleniumis obtained in two forms: (1) red

powder produced by reducinga selenitein an acid solutionwith sulfur diox-

ide; end (2) vitreous or glassy selenium,black in color and describedSE

a super-cooledllquid. Both amorphousfomns are soluble in carbon disulfide.

Seleniumwill burn with a characteristicodor, and will combinedirectly

with hydrogen,oxygen, the hslogens, and many other metals. It is not attacked

by non-oxidizingacids; but nhen heated, it will dissolvein concentratedsul-

furic acid, nitric acid, or caustic alJralis.Nitric acid oxidizes seleniumto

H&eO~.

3. TBE O~DES

The most stable ccmpoundof Se (and its only well-definedoxide) is sele-

nium diotide (Se02) produced by burning selenim in oxygen or sir, Pure Se02

is composedof brilliantwhite needles, It sublimesreadilybut can be melted

6

TABLE II

CHEMICALAND PHYSICALPROPERTIESOF SELENIUM

Atomic Weight

SpecificGravity (solid)

Color (solid)

Melting Point

Boiling Point

Atomic Volume (approx.)

Heat 01’Fozmation, ~X (Csls.)

Atomic R8diuS

Ionization Potentials

Ion volts—

I 9.751II 21.514III 30,079IV 42,902v 73.1C9

78.96

4.26-4.79

dark red

170-217°C

688°c

MC

-25.1

1.5 Augstrom

OxidationPotentials (volts)at 25’c

(a) Acid solution

E&e 0.40 Se -0.74 H#e03 -1.15 Se04=— .

(b) Base solution

%= 0.92 se 0.366 Seoa= -0.05 seed=

without decomposition. In the vapor state, it has a yellow-greencolor. Sele-

nium diotidewill dissolvein water, concentratedsul-c acid, or alcohol.

It can combinewith hydrogen chlorideto form Se02.2HCl,and will form similar

double compoundswith other substances. It can easily be reduced to elemental

selenium.

The characteristicbuznlng odor of seleniumis reportedby Berzelius(6) to

be due to the formationof a suboxide,SeO. It is also reportedthat a mitiure

of SeOz and SeOg is producedwhen seleniumreacts”withoxygen In an electrical

discharge, Seleniumtriotide is decomposedTn water to form selenic acid, and

is stable to 185”c, at which temperatureit decomposesto oxygen and SeOz.

7

4. OIZDATIONSTATES

Selenium cam form compounds havl~ oxidation states of -2 (the aelenidea),

+4 (the selenites),and +6 (the selenates). Polyaelenides,such as Nasez end

NaSe3 are known, but they are leaa stable than the polysulfides.

Selenium IB electronegativelybivalent towards hydrogen and the metals.

In its electropoaitlvebehavior,seleniumhas a valence of +4 in compounds

formedwith most elements;but in combinationwith fluorineit has a valence

of +6. In general, the compoundsof selenium,sulfur, and tellurlum,behave

similarlyand are analogousto each other. The principaldifferenceis in

the lower stabilityof the selenium (and tellurium)compounds,which are

easily decomposedto the element by heat or reducing agents.

SALTS5.

~.1 Soluble Salts

Selenium dioxide 18 a true anhydride,five parts disaoltingin one

part of water. In combinationwith water, Se02 will form seleniousacid

(H&o, ). The alkali selenites.(Li2Se03,Na&e03, &Se03, Rb2Se03j

Cs#3e03) are all soluble in water, as are the acid selenitesor hydro-

selenltesof the type MHSe03, Table III lists some of the more inpor-

tant

5.2

soluble compoundsof selenium.

InsolubleSalts

The selenate compounds of lead, barium and calcium, like the corres-

ponding sulfates, -e insoluble; however, they are leas stable to heat

than the sulfates.

Hydrogen seletidecan form both acid selenides (M%Se) and neutral

selenides (&zSe). The alkali and alkalineearth metals can combine

with additionalseleniumto form polyselenides(~lSex) in the same way

that these metals form polysulfideswith sulfur. Pure alkali selenides

are colorless. Heavy metal selenidesprepared by the action of hydrogen

selenide on solutionsof the heavy metal salts are more or leas strongly

colored. Like the heavy metal sulfides,they exe insolublein water,

and some are insolublein acids.

Selenium can combinedirectlywith nitrogen to form seleniumnitride

(Se~4), which is insolublein water, and only slightlysoluble in benzene,

acetone,acids, and carbon disulfide.

Selenium combineswith sulfur to fomn seleniummonosulfide, (SeS)

and seleniumtisulfide (SeS2). Seleniummonosulfideis insolublein

water and ether, but very soluble in carbon disulfide. Seleniumdisulfide

8

TABLEIII

VOLUBILITYOF SELENIUMCOMPOUNDS

Water VolubilityCompOund Formula Cold Hot— Other Solvent8

Bromide@ Se2Br2 decomposes decomposes Decomposes In alcohol;(Se + H#e03 + HBr) solublein CS2, chloroform,

C&.Br.

SeBr4 deccmpoaea decomposes Soluble in CS2, chloroform,(SeOBr2+ HBr) C2~Br, HC1.

SeBrC13 Insolublein CSZ.SeBr3ClSe$2Br inBoluble decompoEe6 Slightly solublein CS2.

Chlorides Se2.C12 decomposes decompoaem Decomposesin alcoholand(Se+ H#e03 + HC1) ether;solublein CS2,CC14

chloroform,benzene.

SeC14 decomposes decompoae8 Decomposes in acids and(SeOC12+ HC1) alkelia; slightly soluble In

CS2.

Fluorides SeF4 decompoae8 decomposes(*OF.+ SF)

SeF8 dec~oses– dec~oses

Iodides Ss212 decomposes decomposes(Se+ H#e03+ BI)

SeI~ decomposes decomposes(SeOI=+ =)

Nitfldes se4N4 insoluble insoluble Insoluble in alcohol andether; slightly soluble Inbenzene, acetic acid end CS2.

Oxides Se02 soluble soluble Soluble in alcohol, acetone,benzene, acetic acid.

Seog decomposes decomposes Soluble in alcohol and fiS04;slightly sligktly insoluble in ether, benzene,

(SeO~+ Se) chloroform, CCL4.

seso~ deCOnIp08eE decomposes Soluble in ~S04; ineoluble(Se02+ S02) in SOS.

Oxy-sslts SeOBr2 decomposes decomposes Soluble in CS2, CC14, chloro-(H#eO~+ HBr) form, B@34, benzene

SeOC12 decomposes decomposes Soluble in CS2, CC14, chloro-(H@e03+ HC1) form, benzene.

Seol?z insoluble insoluble Soluble in alcohol, CC14

Sulfides SeS insoluble insoluble Insoluble in ether; solublein CS2.

SeS2 inBoluble insoluble Decm.poses in BN03, aqua regia;soluble in (NH4)fi.

9

ia Insoluble

acid. Table

of selenium.

“Handboakof

Tn water amd will decompose only in aqua regia or nitric

III lists Borneof the more Important Insoluble compounds

Additional information on solubilities appe-s in the

Chemistry and Physics” (7),

5.3 Non-isotopicCarriers

In some cases, a hfgh specific activityselenium sourcemust be pre-

pared. A non-isotopiccarrier, chemicallysimilar to selenium,must be

used rather than inactive selenium. Telluriummeets these requirements

aud can be used to sep=ate small quantitiesof radioactiveselenium

High-purity (99.999$)tellufiumia availablecmmnercially. Total helo-

gena, sulfur, and seleniumdo not exceed 5 ppm by chemicalanalysis.

Garrison,et al.(8)

re’potieda procedure in which they separatedradio-

active seleniumfrom an eraenic target using tellurouaacid, precipi-

tating telluriumwith sulfur diotide. They reported that 95* of the

selenium c=fes, and can then be aeperatedfrom telluriumby distil-

lation.

5.4 Coprecipitation

Microgrmn quantitiesof selenium can be collectedby coprecipita-

tion on ferric hydrotide. The weight of the iron present shouldbe 30

times that of the selenium(9). The Iron Is precipitatedwith an excess

of ammoniumhydroxide. A method(lo)for separatingsmall amounts of

selenite and selenateions ia baaed on the copreclpitationof the sele-

nite ion with iron hydrotideat pH 8.4-8.6. Under these conditions,

the selenateion Is not coprecipitated.

6. COMPLEX IONS

Several of the selenium halogen compounds can form complex acids by

adding on hydrogen halide ions. For example,SeBr4 will combinewith H&

to form hexabromoaelenicacid (B#eBre). Hexabromoselenatesand hexachloro-

selenates have

ccmplex acids.

7. CHELATES

been formed by the reactionof al12mli

Their aolubilitiesresemblethose of

halide salts upon these

the selenates.

Selenium forma a chelate In an acid solutionwith sodium dlethldithio-

c=bamate that can be extracted (pH 3) with ethyl acetate‘U)W). The c~-

plex can be extractedinto carbon tetrachloride(13)

, end telluriumis also

extracted.

10

Bode WI. Aanswold(’4)reportedthe quantitativeextraction of the SeIV

chelate of dlet~ldltblophosphatefrom 10~ HCl into CC4, only 40$ of the

te~urium being extracted.

che*(’5) has shown that a 5$ aqueouB dlanrlnobezitinehydrochloride

solutionvIIJ.form a seleniumcomplex In a fotic acid-watersystem that can

be extractedinto toluene at pH 6-7. AlthoughFe+=, CU+2, @5 and other oxi-

danta Interferes,the Fe+g and CU+2 interferencescan be eliminatedby EDT.A

completingat pH 2-3. TelluzYumforms a cmuplex that is extractedbut doet3

not Interferein the colorlmetricanalysis.

8. VOIJICILECcwourms

The distillationof neutral or acid alkali selenldeswith potassium alkyl

sulfatesproduces sJ@l selenldessew (whereR=the alkyl group) and alkyl

selenomercaptansSeFH. The a.lkylseletidesare volatile liquidswith pungent,

repulsiveodors. They readily combinewith, or add on, halogens or oxygen

to fomn such compoundsas (C41S)&eC12 or (C2%)@e0. In addition,they can

add on alkyl iodl.desto form such compoundsas eJ.kylselenonium, e.g.

(C2~)@eI. These compoundsam strong bases and, when treatedwith moist

silver otide, form the correspondinghydroxide.

9. PFLIIKXPAL AIwlYTrcAL m.!EHoDS

9.1 Gravimetric

The gravimetricdeterminationof seleniumis csrrled out byweigb-

ing the element after it has been precipitatedby reductionin strong

acid solutionwith either sulfur dioxide or hydro~lemine hydrochloride(16).

,.2 vohnnetric(’6)

9.2.1 Selenic acid is reducedby hydrochloricor hydrobrmnic

acid. The halogen is caught in a Bolutionof potassiumiodide and

titratedwith arsenlteand thiosulfate.

9.2.2 Seleniousacid is reducedby hydriodic acid followedby

titrationof the liberated Iodinewith thiosulfate.

9.2.3 Seleniousacid in hydrochloricacid solutionIs reduced

by a brown excess of sodium thiosulfate. The excess thiosulfate

Is then titratedwith stand- iodine solution.

9.2.4 2eleniousacid is oxldlzedby an excess of standardper-

manganate solutionin sulfuricacid solution. The excess permauga-

nate Is titratedwith ferrous sulfate or oxalic acid solution.

n

9.3 Colorlmetric

9.3,1 3,3’-rn~nObe~iUne reacts with Se to form an intenee

yellow compound (piazselenol).~eng(15) reporteda procedure for

determiningtraces of Se by extractingthis ccmpoundinto toluene

and measuring the color apectrophotcanetricaldyat a wave length of

420 m.

9.3.2 2,3-DiaminonaphthaLenealso reactswith Se to fomn a

piaaselenolwhich 1s a reddishprecipitate. It may be extracted

into toluene and measured spectrophotometricallyat a wave length

of 380 UP(17).

9.3.3 Seleniousacid liberatesiodine quantitativelyby ofida-

tion of iodide ion. The blue color is developedwith a cadmium-

iodide starch reagent and measued spectrophot~etricallyat a

wave length of 615 mI(18).

v. SELENIUMSKPARA’ITON~ACTIONS

1. SEPARATIONBY P~CIPITATION

Selenium ia separatedfrom moat elementsby the use of reducingagents

in acid solutions. EH.llebrand,et al..(16)

report that Se (and Te) can be

initiallyseparatedfrcnnmost elementsby reductionwith S02 in 3.7 to 4,~

HC1 solution. Gold, Pd, and small mounts of Sb, Bi, Cu, and other elements

are also reduced under the same conditons. Gold can be separatedby filtra-

tion after the mixed metal precipitatehas been digestedfor some times in a

dilute HN03 solution. The seleniumC= then be separatedby precipitation

with E&03 or hydroxylamlnehydrochloride.

Quadrivalentseleniumor telltium can be separatedfrom other elements

by saturatingau acid solutionwith H#(19),

Sexivalentseleniumand tellu-

rium can be completelyprecipitatedfrom 122 HC1 solution at room tempera-

tul-e(20).Sulfides of the copper subgroupmay interfereunder the same con-

ditions.

In their studies,Seath and Besmiah(21)

end Noakes(22)showed that

nitrates of CU+2 and Au+= interferedin the reductionof Se (or Te) to ele-

mental Se (or Te). The nitrateswere removedby evaporationwith HCl and

NaCl, and CU+2 and Au+= were separatedbefore the reductionwith hydroqui-none(23,24).

Selenium (and tellurium)may be separatedfrom many elementsby reduc-

tion of an acid solutionwith stannous chloride. Selenium and telluriumare

precipitatedand can be sep=ated by a brcminatedHCl dissolutionof the

metals followedby a precipitationof Se with S&(25)0

12

Bode(26) has shown that a separationof Se from Te can be effected in a

51 HC1 solutionusing a solutionof tetraphenylarsoniumchloride.Telluium+8

will precipitateand bromide, iodide, fluoride,nitrate,Mo+e, and tie will

interfere.

Ripen-Tilici(27)Snd SPQCU(28) have shown that Se can be detetined as

lead selenate. To obtain this form, Se must be oxidizedto the hexavalent

statewith *02 and precipitatedby a lead salt solution.

2. SEPARATIONBY SOLVENTEXTRACTION

Solvent extractionmethods, used as wparation methods for other analy-

sis techniques,can often be adapted for use in radiochemistry. They can be

quite useful in separatingthe desired radionuclidefrcm .&sampleby either

a carrier-freeor carrier rsdiochemist~ method. Morrison and Freiser(29)

have reviewedthe applicationsof ion-associationand chelate-complexsys-

tems to the detehnation of most of the elements. Some of these are

applicablesa separationprocesses in the radiochemistryof selenium.

Table IV gives a few of the solvent extractionsystems that could be

used for the separationof selenium. Few epecificsolvenbextraction

methods for seleniumhave been developed,but many could be adapted.

2.1 Ion-AssociationSystems

Kitahar.(3°)has reportedthat Sn+2 and Sn+4 can be completely

extractedwhile Se+4 (md As+’, %+’, mdMo+’) iS 01dyp3.I’ti-y

extracted (about L%) from HF solutions of varying concentrations by

ethyl ether and a 4:1 volume ratio of organic-to-aqueous phase.

Using equal volumes of IIFand ethyl ether, Bock and Herman(31) have

shown that only Nb+5, Ta+5, and Re+7 were extractedin amounts greater

than 5*; Se+4 (aawell as Sn+2, Sn+4, As+3, As+5, Te+4, Ge+4, ~5, @3,

@?, h!o+eaud Sb+3) was only partially extracted. However, the extract-

ions of Se+4 and the other ions Incresaedwith increasingHF concentr-

tion. These two studies show differentextractionvalues; however, these

differencesmay be due to the manner in which the metel fluorideswere(32)

prep-ed. Stevensonand Hicks report that Se+e (sswell aa Te+8,

Fe+3, Ga+3, sb+5, and Aa‘s) canbe quantitativelyextractedbytiis~

propyl ketone from anlneral acid-hydrofluoticacid (6E HC1 - O.% HF)

aqueous system. Se+4 (aawell as Sb+3, As+5 and Te+4) is only slightly

extractedunder the8e conditions. In this same study, it was shown that

Se+4 (and Te+e ~d Ta+5) co~d be extractedby diisopropylketone frcnna

6~ H2s04 - O.bg m’ Systemp

At least 3C$ Se+4 can be etiractedfrom a mixture of metal bromides

13

mHLE Iv

SoLsm’rmcmoN sYs-JEMs FOR slImNIuM *

OxidationSkate

IV

IV

VI

Iv

IV

IV

r?

rv

IV

rv

Iv

4.6ME?

20M HI?

@ Hcl-o.g HF

4-% HBr

I.METJog

HC1

30-35$HBr

Na-tiethyldlthio-c-bamate

Pi=selenol-complex of3,3 ~tinobenzitinehydrochloride

Complex of 2,3diamino-naphthalene

Complex withtoluene-3-~dlthiol and10~ HCl

ethyl ether

ethyl ether

diimpropylketone

ethyl ether

o.ca-o.6MdibutylphophoricBCid

methylisobutylketone(4-methyl-2-pentanone)

di-iaobutylketone(2,6-dlmethyl-~heptanone)

ethyl acetate

t oluene

toluene

mixtureethylenechloride- ccl~

%Extraction

4.0

12.9

100

31

<5

100

90

100

100

Reference

30

31

32

33

34

35

36

11,12,13

15

100 17

100 37

* All of theee ❑ol.ventextraction system - also applicable to tellurium.

The Na-dietbyldithiocarbamatesystem is the only practical method for separating

Te from Se. Tellurium can be extracted from thiB ayatem into carbon tetrachlor-

ide atpH 8.5 - 8.7; selenium ia not extracted,

14

(~ to @ E&) into ethyl ether(33). AU+3, Ga+3, In+3, T1+3, Sb+5, Sn+2,

Sn+4, and Fe+= qU8ntit8tiVely extract from thie ByBtem; As+3, sb+3 and

Mo+e extract slightly;Cu+2 and Zn+2 do not extract.

Scsdden and Ballou(34)

have shown that leas than 5$ Se+4 (and Te+4)

till extract Into O.@ or O.@ di-n-butylphosphoricacid (DBPA)frm a

1# HN03 solution. A 1:1 orgamlc-lio-aqueouavolume ratio was used In

these studies. Yttrium, Sn, Mo, Nb, Ta, Zr, and In me extractedIn

concentration v~ng from 5 to more than 95$ fram the same system.

Selenium (esweu as Tej Fe, Ge, Sn, As, and Sb) can be quantit-

tively extracted into methyl iBobutyl ketone I’rcnnvarious concentratlon8

of HC1(35). This study determined the approximate ranges of extract-

ability for metallic Baits of the~e and other elementB.

Kuroda(%) used a HBz=dllsobutylketone Bystem for the rapid radlo-

chemicel separationof Se7sm. Selenium (8s well aa As, Sn, Hg and Au)

can be quantitativelyextrhctedinto dilsobutylketone frmn 30 to 35$

HBr. The interferingelements can be strippedby shakingwithED’TA

~d sodium t-rate, or with sodium hydroxide solution.

2.2 Chelate Complex Systems

Selenim can be extractedfrcm an acid solution (PH 3) as the

Bodlum diethyldlthiocarbamatesalt with ethyl acetate (U,M) .

Se+4 (andTe+4) will also forma complexin an acid solu~~ (pH 5-6)

by use of O.~ solutionof Bodium diethyldithiocarbamate . The

conplex can be extractedinto CC14. The addition of a 5$ solutionof

EDIM to the s stem assists in masking out other extractableelements.,hew(15$ haB 8hown that a 5$ aqueous diaminobenzidlnehydro-

chloridesolutiontill fozm a piazselen@ cmnplex in a fomnic acid-

water systm that can be extractedat pH 6-7 by toluene. Fe+3, Cu+2,

@5j and other ofidantsinterfere;however, the Fe+3 and Cu+2 inte~

ferences can be eliminatedbyEDTA ccxuplexingat pH 2-3. Vanadium

(V) otidizes diaudnobenzidlnepreventingthe fomaticm of the cmn-

plex, but traces of vanadium have Httle effect. Tellurlumis

extractedbut does not interferecolorimetricalJ.y.

Lott, et al.(17) used a similar 8yetem for extractingSe. A l?

aqueoue (0.~ HC1) solution of 2,3-dieminonaphthalene was used to

complex Se; and the complex was extracted, at pH 1.5 to 2.5, into

toluene. hlmking agents were used to prevent interferences.

Watkinson(37) etimcted Se from strong HC1 solutions (QO~) 8s

the Se (IV) complexwith

lene chlorideand carbon

with toluene-3,&dithiol

toluene-3,~dithiol into a mixture of ethy-

tetrachloride. Elements that also react

are Te (~), Pd, Au, W (VI), andRe (VII).

15

3. SEPARMICONBY VOLATUITY

Selenium (or tellurium)in the selenide (or telltide ) fom can be

sepwated fran metalm whose chlortdes- nonvolatileby pasdng C12 gas

into a hot aqueous solution(38)

. Hydrochloricacid gas csnbe used

instead of C~ to sep=ate either”Se+4or Se+e. Selenim can be 8epua-

ted from telluriumby a distillationmethod in which HC1 gas is passed

into a H#04 solution. The distillateis caught in cold water, and

Se+e 18 precipitatedby adding S02. Either Se+4 or Se+e can be quanti-

tatively~eparated fran te~urium by passing C02 gas into a l@Tobromlc-(40)

phosphoricacid solution . Selenium o~chloride and SeOBr2 ( as well

as TeOC~ and TeOBr2) are volatile from 61 HC1(41)

0, 6~ ~(@-44)SOk

tiong at temperaturesabove 100”C. Arsenic, antimony,tti and germanium

are also volatileunder these conditions.

4, ELlmImLrmc sEPARA!tToN

Electroseparationand electrogravlmetrymethods for seleniumme not

extensivelyreported. Only a few electroanalysistechniquesexist for the

determinationof seleniumby amperometryand coulometry;however,a consi-

deration of these ml t be profitablefor use in rediochemistry. For example,

Lingane and NiedrachF +4 with CUpfic COPper45)report on the titrationof Se

in an mnmonicslmedium. Se+4 is reduced to Se+2, and cupric selenideis

only slightly soluble in thi6 medium. The potentialof the droppingelec-

trode is such that the tetreazdnocupricions and the eeleniteions are

reducible;its value will increasewhen excess cupric ion is added.

and swift(~)

Rowley

have used a coulometrictitrationof thiosulfatefor the

determinationof Se+4. The back-titrationprocedureswere followed. In one,

en excess of iodide is added to a strong seleniousacid solutionand iodine

iB liberatedand reducedwith sodium thiosulfatesolution,the excess thio-

sulfatebeing detemined by coulometrictitration. In the second procedure,

excess thiosulfateis added so that the selenlousacid is reduced to sele-

nopentathionate(SeS40e),and the excess thiosulfateis dete?.minedby coulo-

metric titrationwith iodine. More accurateresults (YO.1~for severalhun-

dred micrograms)were obtainedby use of the secondmethod.

5. HEFAB-ATIONBY ION EXCHANGE RESINS

Kraus aud Nelson(47) report that selenite (Se+4)and telluriteshow

good adsorptionon an anion resin column as chloride complexes. As en+4 ha de it poesible tO Sepwate ‘t ‘rmexample,this behavior of Se

As+a ~d Br- by use Of solutions of various N&Cl concentrations. AS+3

ie removedby elutionwith O.01# ~Cl; Se+4 with 0.5CljNI&Cl; and Br

16

with 5.OFJ~C1. Attebury,et al.(49)

, and Aoki(’g) report that se can

be sep=ated from Te by adsorptionupon an anion resfi column from ~

HC1, A mlxlmre of ~ HC1 and ~ NH&NS was used as the eluant.

Lederer and Kertes(50)

used seleniteend tellu%te ions in a study

concernedwith the use of a Ibwex-re,ein-lmpre&ate& paper. Optimum con-

ditions for wepsxationwere calculatedby consideringthe relationship

of the ion adsorptionwith the pH of the aqueou6 acid used as elusnt.

6. SEPARATIONBY PAPER CHROMMIWRAPHY

Levi and Banon(5’)have used paper

of BI=o, pb=o, Po, Se, and Te in ~Os

ture was used as the solvent and a good

obtdned. Crouthameland Gatrousis(52)

chrczaatographyto separatemixtures

BOlUtiOn8. A butanol-propanolmix-

separatlonof each elementwea

also report on a similar separation

of Se, Te, Po, and Bi by peqer chromatography. Specific separationsof Se

(ss se+4) from teU&5~ (SS Te+4) in HCl, ~03, and HBr have been studied

by Bursta12, et al. , Lederer(54), md Weatherley(55). Solvents such

as mixtures of butanol-methanol,butanol-water,and butanol-HClwere uOed

to effect the separation.

VI. DISSOLU’ITONOF SAMPLES CONTAININGSELENIUM

When dissolvingselenium-contairihgseanpleO,it is necessaryto use

techniquesthat will minimize the 10BS of Se by volatilization(56)

. Sele-

nium is easily volatilizedas Se02S2HClfrom strong HC1 solutionsby

heating. Very little Se is lost by heating dilute HCl solutionsat

temperat~s” below 100”C. The presence of alJmli salts do not prevent the

volatilizationof Se. The volatilemonochlorideof selenium (Se2C12)can

be formed in strong HC1 solutionsby the action of reducing agents. The

neductionof Se Bhouldbe performed rapidly,with an excess of reducing

agent, to reduce the Se to the element. No loss of Se occurs if sulfuric

acid or perchloricacid solutionsof seleniousacid - evaporatedto dense

fulnes(s~)unlees there are chlotidesor bromidespresent.

Some selenidesattack platinum during a fusion process. The fusion

can be done with N@2 or a mixture of N&C03 and KN@ in a nickel or zir-

conium crucible. Fbion with KCN may cause sane loss due to volatili~ation.

The addition of inactive selenium cexrier to the mixture before dis-

solution begins wild assist in achieving an exchmge of the radlonuclide

with the carrier atom. The chmical states of the hradlated seleniumand

the carrier seleniumshould be the same dting the dissolutionprocedm

so that any losses that occur will be accountedfor in the chemicalyield

determinationof the added inactive carrier.

17

1.

For

may

and

MEmLs AND O.xJIIEs

Acid dissolution18 TeC~ ded for the asBay of metals and oxides.

exszuple,coppermetal can be dissolvedin nitric acid; iron and steels

be dissolvedin HN03, HC1 and HC104; lead muat be fused with N~COg

Na#OS in a nickel crucible. Insolubleoxidesmaybe fuse~=~th N@Oz

or sodium carbonateand potassim nitrate in a nickel crucible’>”).

2. QXG!rs

Nitric acid

that no selenium

3. =

Ore samples

and HCl will decmpose most selts. C= should be taken

is volatilized.

can be fused with N@2 or a ml- of sodium carbonate.and sodium nitrate in an iron or nickel crucible(59J. Some ores can be

decomposedwith 1:3 BN03 followedby funbg with s~ic acid to remove

BN03. Ores containingselenidescan be deccmrposedby heating at dull red-

ness h a current of C~ and catchingthe volatile chloridesof seleniumin

1:1 dilute HC1.

4. BIOCHEMICALSAMPLES

Biochemicalsamples can be &ccrmposedby destroyingthe organicmatter

with a 1:1 aahing mixture of nitric end perchloricacids(60). Tissues can

be decaposed by fusing with N@@ (61). SmsJl amounts of Se in vegetation,

grains, and anhal matter have been z=eleaaedfrom these materialsby dis-

tillingwith HSr(62). Organic or biologicalsamples cam be decomposedIn a

SchUnige~type ~gen-combustion flask; the gases are absorbedin a HC1

solution containinga selenium carrier. Gorsuch(63), in a series of ra&Lo-

chemicalinvestigationsconcernedwith the recoveryof trace elementsfrom

organicmatter, has evaluateda number of dissolutionmethcds for recover-

ing trace Se frmn similarmaterials. The results of these studies showed

that Se was lost by volatilization.

5. mm

Glass samples

acida(64). Rubber

and Sll@r.

may be taken into solutionwith hydrofluoricand nitric

is deccnnposedby a fusionwith a mixture of Ns20z, NaNOs,

VTI . HAZAFUM

No matter what method is used

AND PRECAUTIONS

to decomposea sample, adequatesafety

18

precautionsshouldbe followed. The toxicologyof most elementalcompounds

has been reportedby Pieters and Creyghton(65)

, and It should be consulted

for infonuatlonon handling selenium-containingmaterials safely. Due to

the volatilenature of some of the selenium compounti,radiochemicalRepa-

rations requiringheat should be carried out in a well-ventilatedhood.

Safety practices are always importantin rSdiOChemi6try. The disch=ge

of radioactivityby explosionor evolutioninto a laboratoryarea can be

hazardousand can result in wide-spre.%iradioactivecontamination. Thus,

some souxce of informationon safe-handlingpractices in processingradio-

active samples shouldbe consultedbefore a rsdiochemlcalanalysisIs

undertaken. One such source is the Oak Ridge NationalLaboratory’sMsster

AnalyticalMsmual(66). Other similar sources of informationexist and

shouldbe consulted.

VIII. COUNTINGTECHNIQUES

The analysisof smple materials containingseleniumrsdionuclidesmay

be completedeither by a direct (non-destmctive)measurementof the radio-

activityof the particularradionuclideor by obttiningthe radionuclldein

some form by radiochemicallyprocessingthe radioactives.mple. The choice

of techniquedepends upon the seleniumradionuclidesbeing measured, and

such characteristicsas half-life,type of radiationemitted, and the ener&y

of the radiations. An excellentsource for countingtechniquesis the mono-

graph by OrKelly entitled,Detectionand Measurement of Nuclear Radiation(67).

Table I shows the nuclear characteristicsof each of the known radio-

active isotopeaof selenium. Those usually encountered by the radiochemist

are Se75 (121 d), Se77m (17.5 see), Seem (56.8m), Sesl (18.2m) sndse=

(25 m). These isotopes are produced as a result of a number of nuclear

reactions on stable isotopes, either of selenium or other elements. Se=m

decays to Seel by ismnerlc transition; Se= decays further to stable Br81

by the endssion of 1.3@-MeVbeta radiation. Se= decayswith the half life

of Seelm (56.8m), stice the two states are intransigentequllibtium.“The

measurementof Se= must be completedby beta counting,using 4 rror 2 n

Geiger-MuelJeror proportional-betacounters.

The other isotopeadecay by means of gamma radiationsand can be measured

with a gamma scintillationcounter or gsmna scintillationspectrometer. Figures

2 through 6 give gamma-rayspectra of the ss7s(87), Se7s(87),~mn(~), See1rn(89

~~ sem(90) radioisotopes.

Although a number of radionuclidesof seleniumare formed by radiative

capture in stable selenlunisotopes,L21-day Se75 and 3.g-minuteSe79m have

been most extensivelyused as the analyticalindicatorsfor the activation

analysis of selenium. However, these are not the most sensitiveindicators

19

for a seleniummalyais. Table V is a tabulationof the calculatedspeciflc-

saturationactivitiesof the nuclides formed by radiativethemsl-neutron

capture in the stable selenium isotopes. Activationcross sectionswere

ccm@led frm Informatim appearingin reportsby Eughes and Harvey(Q) ~

by Weigman(70). Krsmer, etal~m) discuss the metastableisaners of eele-

nium, emd show that the greatest sensitivitycan be obtainedby using l~.5-

second Se7m as the radioactiveindicator.

Seleniumm, a metastableisomer of stible Se=, decays with a half-

life of 17.5 secondswith the emission of 0.160-Mevgamma ~. Its

short ~-life has precludedthe use of Se- in an activationanalytical

scheme in most laboratories. In fact, there appear to be only two refer-

ences(61)~) that report quantitativeseleniumanalyaesbased onthia

particularnuclide. With rapid pneumatic-tubesyatems, s~les carIbe

transferredfram the irradiationfacillty to the gamma scintillation

counter inafew6econd3. OkS&(~) haE recentlyreported on the use of

gamma spectrometryto detect and &tennine t@ radioactivityof Se-

(17.5-see.) in nondestructiveanalysesof neutron-imsdiated sulfur,

ammonium cmrpounds,end ores for trace selenium. Putman and Taylor(72’73)

have reporteda techmlquefor ualng Se75 (121 d), for detenuining trace

selenium in glass. ‘I’@ made measurements of irradiated sauple & glass,

with and without selenlum, simultaneously, with two IieZ(Tl)scintillation

TABLE V

CALCULATEDSPECIFICSATURATIONACTIVITIESFOR SELENIUM

RADIONUCLICESPROEUCED BY THERMAL NEU’ITONCAPTURE

‘~ecificStablell&lll@

*74

*7e

%7 s

Se*

*8O

*S2

sea2

Isotopic

T0.87

9.02

23.52

49.&2

4$),82

9.19

9.19

Radio-nuelide

*75

Se77m

Se7m

Seslm

*81

Half-Life

l’ld

17.5s

3.9m

56.&tI

18.2m

70s

25m

ActivationCros8-section

(bma )

26

22

0.40

0.030

0,5

0.050

0.004

SaturationActivity (a)

1.7 x lCP

1.5 x 1o11

7.2 Xld

1.1 x ld

1.9 x ldo

3.5 Xlos

2.8 x 107

(a) dis/sec.g, baaed on a themsl flux of 1 Xldg neutrons/cm2. 8ec.

20

0.51!mihilotio

7’.1-hour sir:“KJ”;21 NaI :

Absorber: 1.!8 g/cm2 Be+0.1 Cu sandwich -

Source dist.: 10 cm (c)Energy scale: KeV/PHU (Cd -

%

\

.4e

e.

I

-Lo 800 Kx )0 12

PULSE HEIGHT

10 1400

FIGURE 2, Gommwmy spectrum of ‘?.l-hour Se73.

————

—

—

—

2(

FIGURE

(

—

.

.2$33, .:

.410)

6)

4

64

l-----0 400 6’

-i-

—

—

—

—

—

121- day Se753“X3*’- 2 N(ll

5/’19/58Absorber: 2CX3rng/cxnz -source C!istfmce: IOcm(c) -Eh3rgy scale: ~ lKev/PHU

PULSE HEIGHT

3, GQmmQ-rQyspectrum of

22

TI

)0 1200

121 -day Se?s.

—

I

.16 Mew

—

—

$“!

11

,y%#;II

~. IE

—,d I

~q’d tI\&

— Cumulated difference— spectrum showing first W

1- half - minute decay.

f

$7’.!5-sec.SELENIUM

77M

I I

23

se “m 56.8 fTtifl.590 mglcm2 Be(horne?ry: 40701W.= !5.5 kev

ENERGY ---+--

FIGURE !5, Gammo-ray spectrum of 56.8 min.SeaB%

24

0A4Iu

KY

!02

10

LOc

n

3

Se831n

.69

+se83.84

FIGURE 6,

3 0.6 c

I I 1

SELENIUM-83Wr@e: Se, 1.0375 gramsGold disc: 15.5mg; !1,053 CX5mir

11/’24?’!59 0. A

Se83m

1.01

I

3 1.2 1.5 1.8 :

ENERGY, Nlev

GammQ-roy spectrwm of Sease

25

counters; the responseof the counterscan be subtractedto leave only the

Erion, et al.’74) (75)selenium-75activity. and Fineman,et al. have also

determinedtrace seleniumin sulfur and ore concentratesby a nondestruc-

tive analysismethod.

IX. SETJ!RATTONPROCEDURESFOR SELENIUM

The radiochemlcalproceduresdescribedin the folloVingpages have been

divided inta four.cat.egories.In each category,special informationregard-

ing the method used, aep=ation time, type of bcunhardment,etc., appems as

part of each procedure. Wheneverpossible, an evaluaticmof the procedure

is made concerningits use in the decontaminationof other radioactivespecies

from the radioactiveseleniumisotopes.

“Activation-analyaisprocedures”deacrib.evariouamethods used to deter-

mine microgram and aubmicrogrememounta of seleniumin various typea of amplea.

In the activation-analyaisprocedu=s cited, a carriertechniquewas used to

separatethe radionuclidefrcunthe rgioactive mixture. In the procedum,by

Kuroda(36)the c~erwas labelledwith Se75. The chemicalyield can be75 in the find sample wfth ‘hedetermined by comparing the peak =ea of Se

Se75 &ded with the Cufiero

Moat proceduresdescribingthe prep-ation of radioactivetracera use

carrier techniquesto aep=ate the radlonuclidefrom the targetmaterial.

In the prep=ation of smne radionuclides,however, it la neceaaaryto sepa-

rate them without any additionof c~er. These procedures appe=”under

a aepsrate classification: carrier-free separation. In addition to the

procedures cited, It should be poaaible to uBe ion exchange in the carrler-

free sepexationof radioactiveseleniumisotopes.

Procedureswe also includedfor the emlysia of fission-productacti-

vities in plant-process solutions.

26

x. INIEX OF SEPARATIONPROCEDURES

1. ACZEVA!TZOWANALYSIS PROCEDURES

1.1 Metals and Alloys, BiologicalMaterials,Waters . . . . . . . 28

1.2 Ore Concentrates,Slags,Waate Gase8. . . . . . . . . . . . . 32

lm3Stony Meteoritea. . . . . . . . . . . . . . . . . . . . ...33

1.4 Fertilizers,Tmnato Tissue, Huron Blood . . . . . . . . . . . 34

1.5 SildcateRocka, Sedhants . . . . . . . . . . . . . . . ...35

1.6platinum Met~. . . . . . . . . . . . . . . . . . . . . . . . 36

2. TRAcER-PREPARAmoriPROCEDURES

2.1 Frmn Arsenic. . . . . . . . . . . . . . . . . . . . . . . . . 38

2.2 FrcenBismuthMetal. . . . . . . . . . . . . . . . . . . . . . 38

2.311rom Uranyl Nitrate. . . . . . . . . . . . . . . . . . ...39

3. FISSION-PIMXXKTPROCEDURES

3.1 Ilssion-productSolutions . . . . . . . . . . . . . . . . . . 40

3.2 POIYphe~ls . . . . . . . . . . . . . . . . . . . . . . . . . 41

4. CARRDZR-= SEPARATION PROC3LIJRES

4.1 FYom Szilard-ChalmereReaction. . . . . . . . . . . . . . . . 42

4.2 horn IkuteronEambardmentof an Arsenic ~get. . . . . . . . 43

4.3 FromumilRll Fls6ion. . . . . . . . . . . . . . . . . . ...44

5. CARFCtERPREPARATIONAND S~TION. . . . . . . . . . . . . . 45

27

1.1 Metals aud Alloye, Biolo@cal Materials, Waters (76,77-79)

Procedm used in: Activationaualyeis

Method: Volatilityand precipitation

ITucle= banb~t: *74 (n,y)s875

*so(n, y)*U

S& (n,y)Seel

Procedureby: Leddicotte,G..W.’76)

Chemicalyield of carrier 75-W%

.&pLmationtime: 1.5 hours

I&gree of purification: Btudlemwith radioactivetracersof Aa, W, Sn, Sb, Ha show thatdecontamrlnatiogiB better than108 for each

E@paent required: neutron source and stmdardI_ehoratoqequi~nt

1.1.1 Irradiaticmof Smuple Materials

I“madlatebmoun euwunlm of test (Note1) and comparator

(0.C$25to 0.030 g of Se metal to neeze,et0.1 lug)samples (Note2)

in a neutron flux of at leaat 5 x @l n/c#. sec for 16 hours.

(Note3). Use mall quartz tubes, polyethylenebottles,.or alu-

minuM foil to contadn the s.mples..

1.1.2 Preparatim of Cmp aratar Smnplea

a. After the irradiation,quantitativelytmazmfer”the

cmparator omples (Note2) to a MM-ml volmetric flack, dis-

solve it in a mall meaeured volume”of 6M BHOg, then dilute the

solutionto 100 ml with water. Mx well, ueing stie-hendmng

practicesfor radioactivemateriels.

b. Pipet a 1.OCHul aliquot of this solutioninto a

second 10WDI. volumetricfleak; dilute to volume with water

and ndx well.

c. Pipet a 1.O&nl aliquot of this solutioninta a 125-ml

@ems distillationflack. By meane of a volumetricpipet, add to

the mme distillationflack 2.~ ml of a standardcarrier solution

of known Se concentration(Note4). Also add 1 ml each of hold-

back carriersof k, Cu, Co, Fe, IVa,and Sr (Notes5 end 6). Con-

tinue with Pti 1.1.4 helm.

28

1.1.3 PrepWatlon of Test Ssmples

.9. If the sample is a metel or tioy, quantitat~vely

tramfer the irradiatedtest portion frcnzthe qu.&tz tube or slu-

minum wrap to a 125-ml glass distillationflask, and then add, by

means of a volumetricpipet, to the same distillationflask 2.00 ml

of standard cexrler solutionof known Se concentration. AhO add

1 ml each of holdback caxriersof Aa, Cu, Co, Fe, Na and Sr (Notes

5 and 6). To this tixture, add dropwiseenough concentratedmine-

ral acid to dissolve the sample completely. If neceasaxy,heat the

mixture to effect solution. Continuewith Part 1.1.4 below.

b. If the sample is an aqueous liquid,pipet an aliquot

of the irradiatedportion into a 125-ml glass distillationflask.

By means of a volumetricpipet,”add to the seinedistillationflask

2.CO ml of a standardcarrier solutionof known Se concentration.

Also add 1 ml each of holdback carriersof As, Cu, Co, Fe, Na, and

Sr (Notes5 and6). Continuewith Part 1.1.4 below.

c. If the sample is biologicalmaterial (plant ash, tissue

ash, bdy fltid, etc.) or if it is an organic liquid (a petrochemi-

cal or one of its derivatives),pipet a luwwn aliquot, or quantita-

tively transfer the total amount of solid, to a 125-ml glass dis-

tillation flask. Then add (by means of a volumetric pipet) to the

same distillation flask 2.00 ml of a standti carrier solution of

known Se concentration. Also add 1 ml each of holdback cerrlers

of As, Cu, Co, Fe, Na and Sr (Notes 5 and 6). To this mixture add

3 nil of ~0, 1 ml of @ HC1, ,md 15 ml of BN03-HC104mixture. ~SO,

put 2 or 3 glass beads into the flask, then heat the solutlonat a

nderate temperature(60”C)until all of the HNOg is removed and

HC104 condenseson the neck of the flask (Note7). Digest the mix-

ture in this manner frcun1 to 2 hours. Remove the flask from the

hot plate, cool it aud continuewikh Pert 1.1.4 below.

1,1.4 RadiochemicalSeparationof Selenium

a. Add 10 ml of concentratedHC1 and 10 ml of 48$ HBr to

the distillationflask and place a 50-ml glass centrifugetube at

the end of the distillatetube. Add 10

solution)to the centrifugetube. cool

an ice bath.

b. Connect the condenserhead

bubbling alr through the mixture in the

ml of water (or WmLli

the tube by placing it in

to en air flow end begin

distillationflask. Heat

29

the flask (an open fl=e can be used) to boiling. Continue distil-

lation process for at least 5 minutes (Note8).

c. Remove the centrifugetibe containingthe distillate

fractidn from the ice bath, then neutralizethe solutionby adding

concentrated~OH dropwiae (Note 9).

d. Acidify the solutionwith 2 ml of cone. HCL. Add 4 ml

of @ H@33 solution, Stir the mixture until the aelenioua acid is

reduced to elemental Se. Centrifuge the mixture; tiscti the super-

natant liquid.

e. wash the precipitate once with 15 ml of hot water.

Centrifuge; discard the wash liquid. Add a 10-ml volume of hot

water to the tube and stir.

f. Rllter off the Se metal thr&gh a weighed filter paper

(MunktellsNo. 00 or Whatman No. k?) held in a Hirsch funnel;wash

the precipitatetwice with 10-ml portions each of &O, 95$ ethyl

alcohol, and ether.

~. Dry the precipitatefor 30 tinutea in a dqlng oven

at llO”C (Note10). Weigh the Se metal precipitate (Note11) and

filter paper on am analyticalbalance. Then mount the precipitate

for the refkloactititymeaaurements.

1.1.5 Measurementof the Radioactivityfrcm Se75 (and/orSe= or

Se-) and Calculationof Inactive Selenium Content of the

originalSSrQle

a. The analyses involvingthe meaeurement of Sem must be

completedby beta counting. S-e= m a ha,lf-ufe of 10.2 tiutea

end decays to stible Bra only by the emission of 1.3&Mev beta ra-

diations. These mesaurementa can be made with a Geige~Mueller

counter.

The analyses involvingthe measurementof Se75 and Se-must

be cczzpletedbygamma couuting. Se75 has a half-lifeof 121 days

and dec~ by means of electron capture and @ma radiations of

various ener~es (chiefly, o.u1, 0.136, 0.27, 0.28, 0.405 b,

plus others). Se- has a half-lifeof 57 minutes and decays to

Sea (18.2m) by isomeric transitionwith the emissim of O.10>Mev

gamma radiations. These measurementscan be made by means of a

~ scintmatim comter or a gwma scintillationspectrometer.

In the use of the latter, the @or gamma radiationsare measured.

b. FolJowingthe -oactive messurements,the observed

radioactivityis correctedfor loss of carrier during the experi-

ment, half-life of the seleniumisotopemeasured, and the weights

30

of the tei3tand cmqxrator semples. A comparisonof these cor-

rected radioactivitiesbecmnes a measure of the stable selenium

content of the test ssmple:

Percent stable Se in test =sample

NOTES:

1. At least O.lGg

CorrectedSe radioactivity: in test smupleOorrectedSe radioactivity: in cmnparator

ssmple

portions of solid samples (metals,aUoys,

tissue, etc.) shouldbe used. Liquid ssnples (water,body fluids,

etc.) should be 1 to 20 ml.

2, Compsxatorsample may be either Se metal or a solution of

a Se cmpound. If a solutionis used, an aliquot of the irmdi-

ated solution containingat least 20 micrograms of Se can be

pipetted tirectlyinto the distillationflask.

3. The sensitivityof the method is such that 2 x l~s gm

of Se can be determined. The sensitivitycan be improvedby

use of higher neutron fluxes.

4. As seleniou2acid (E&3eO~),Se+4

10 mg/ml.

5. Holdback carriersshould be tie

of desired elementalspecies.

concentration

up to contain

6. Solutionsof ions of other elementsmay also be added

e.aholdback carrLers.

7. If the biologicalmaterials is a fatty substance,a Wet

digestionwith HN09-&S04 mdtiure should be used to effect a

solution.

8. Telltium, As, Sb or Ge can follow,wholly or in part,

through this distillationprocedure. In most of the materiels

analyaedby this method, the radioactivecontaminantswere in

minor concentrations,or completelyelhdmated, in the reduc-

tion of Se to elementalform.

9. The Br2 color of the solutiondisappearsduring neutrali-

zation.

10. If the Se= or

p=t of the procedure

measurements.

Sem radioactivityis to be measured, this

cam be completedafter the radioactivity

31

Il. By ccmpexingthe final weight of the Se-metalprecipi-

tate obtainedhere with the theoreticalyield expectedfor the

amount of Se carrieradded, it is poaaible to determinethe

chemicalyield of the expertient. The chemicalyield correc-

tion is then used to determinethe emoumt of Se75 (end/orSee’

or Semm) recoveredduring the separationprocess.

1.2 Ore Concentrate, SISRS,Waste Gases(75)

Procedureused in: ActivationanalyBis

Method: Volatility and precipitation

Type of bombardment: Se74(n,7)Se75

Procedureby: Fineman, et al.(75)

Chemicalyield of curler: 50-00$

separationthe: Several houm

Degree of purification: Excellent frmn other volatileimpurities

Equipment required: Neutron source and standardlaboratoryequipment

1.2.1 Procedure:

a. Irradiate samples (0.1 to 1 g) in a nuclear reactor

for 14 days at a flux of 4 x ldl n/cm2,sec.

b. Mix a weighed amount of Se (10-100 mg) thoroughly

with irradiatedsample and fuse the mixture in a nickel or iron

cruciblewith 25 grsonsof Na20z at 9OO-1OOO”C.

c. DLssolve cake In 50 ml of water. Cool solution and

neutralizewith “(1:1)H&Q. Add at least 50 ml more of concen-

trated &S04 to the solutionand evaporateto 100 uL. To separate

Si02, boil the solutionfor 15 minutes, then cool to 60 to 70°C.

Add 15 ml or 5$ gelatin solution and bubble air through the solu-

tion for 30 minutes. Add hot water (50 ml) to the solutionand

filter the Si02. Evaporate the filtrateto 100 ml, cool, end

then transferto a distillationflask.

d. Add 100 ml of 4~ HBr, contahing 7 ml Br2, to the

flask, and distill the mixture into 10 ml of water; collect 40-

50ml distillate.

32

1.3

e. Neutr.sJlzedistillatewith N&OH, add 10 ml HC1 and

1-2 g hydrazine sulfate. After a 12-hour digestion,filter,

wash with water and ethanol, and dry at 105’C; weigh and mount for

the radioactivitymeawuement.

NaI(Tl

manner

lyzed.

f. Measure the Se75 gmzaa radioactivityby use of a 3“ x 3“

scintillationcrystal.

g. Irradiateand process compmator s~les in a similar

to obtain the Se concentrationof the materialsbeing ana-

Stonv Meteorites(m)

Procedureused in:

Method:

me of nuclear bombardment:

Procedure by:

Chemicalyield of c=rier:

Sep=ation time:

Degree of purification:

Equipment required:

Activationanalysis

Fusion, precipitationandion exchange

Se74(n,7)Se75

Schindewolf’80)

Quantitative

Several hours

Decontaminationof >104 forAg, Ce, Co, Cs, Hg, Ir, RuSb, Sc, Ta, Zn, and Zr.

Neutron source and standardlaboratoryequipment

1.3.1 Procedure:

a. Irradiatepowde~d meteorite samplesweighing 0.050

to 0.20 grams.

b. Add 0.020 g each of Se and Te to the irradiatedsample

and fuse the mixture in a nickel cruciblewith 1-2 grams of NQ02.

c. After cooling,dissolvethe cake in 6~ HC1 and boil

the mixture. Reduce Se and Te to elementalform with S02 gas.

a. Dissolveprecipitatein aqua regla and make the solu-

tion basic with N&OH. Scavenge impuritieswith Fe(OH)3.

e. Acidify the solutionwith HC1 and then adsorb Se and

Te on a Dcwex-1 (100-200mesh) anion-exchangeresin column. Sele-

nium can be sepuated from Te by eluting it from the columnwith

3 to ~-columnvolumes of 31 HC1.

33

1.4

f. heat the acid solutionwith S02 gas to reduce Se to

the elementalfem. Collectprecipitateby filtration,weigh, and

mount for the radioactivitymeasurement.

g. Measure the Se75 gsnma rsdioactititywith a 3“ x 3“

NaI(TL) scintillationcrystal.

h. Irradiateand proces8 comparatorsamples in a similar

manner to obtain the Se concentrationof the meteorite.

Fertilizer, Tomato Tissues, Human Blood(60)

Procedureused in: Activation

Method: Volatility

analysia

and precipitation

Type of nuclem bomb~nt: Sem(n,y)Se=

Procedureby: Bowen and Cawse(60)

Chemicalyield of carrier: 7@

Separationtime: 40 minutes

Ikgree of purification: Decontaminationfrom sxsenic,bromine,manganese, sodiumand zinc was found to besatisfactory

Equipment required: Neutron source and standardlaboratoryequipnent

1.4.1 Procedure:

a. Irradiate samples in a nuclear reactor for 18 minutes

at a flux of l&2 n/cm2.sec.

b. After irradiationtransfer the sample to a beaker con-

taining 10 ml of asblngmixture (1:1 16~ HNOg-7@ HC104) and-25 mg

each of As, P, Mn, and Te carrier solutions.

c. Heat solution until organic is destroyedand fumes of

perchloricacid evolve.

d. Transfer acid solutionto distillationflask with 5 ml

each of HC1 and HBr.

gas,

e. Collect

Distill for 4 ndnutes using N2 as a cwrier

distillatein 50-ml centrifuge

5 ml of HC1, 10 ml water, O.lml of

Shell Chemical Company) and 2 drops

34

Teepol solution

of Mn carrier.

tube conteini~

(wettingagent,

f. Pass sulfur dioxide through solutionfor 1 minute end

centrifugethe seleniumprecipitate.

8. Dissolve the precipitatein about 0.25 ml of bTT@.

Add ten ml of hot water, 0.1 ml of ~02 and 5 ml of HC1, and pre-

cipitatethe Se again with S02.

h. After separationby centrlfugation,wash the precipi-

tate with water and acetone,and transferto a weighed eihnnlnum

counting tray with acetone.

1. After the sample is C&y, count the beta-actititywith

an end-windowGeiger counter. Check radiochemicalpurity by com-

paring decay curve~ of samples and standards over several half-

lives.

il- After counting,weigh the seleniumto obtain the chemi-

cal yield of the carrier.

k. Irradiatecomparatorssn@es and process in a simila

manner to obtain the Se concentrationof the materialsbeing ana-

lyse~.

Procedureused in:

Method:

Type of nuclear bombardment:

Procedure by:

Chemical yield of carrier:

Separationtime:

Ikgree of purification:

Equ@ment required:

1.5.1 Procedure:

Activationanalysis

Solvent extraction

Se7e(n,7)Se7em

Kuroda, R. reportedby

Mei*e(36)

. 6%

10 minutes

Good except for iodine radioactivity

Neutron source and standardlaboratoryequipment

a. Irradiatel-g sample in nuclear reactor for 10 minutes

at a neutron flux of 2 x ld2 n/cm2.sec.

b. Fuse the sample with 6 g of N*02

Se curier labeledwith a lumwn amount of Se75

35

containing 30 mg of

(121 d).

c. Cool the cruciblein an ice bath; put the crucibleinto

a beaker; and add successively10 ml of &O, 10 ml of formic acid,

35 ml of HC1 end 75 ml of KBr.

d. Filter off the precipitatedsodium salts.

e. Add a few grams of hydroxylemlnehydrocblorldeand

1~ ti of 2,6-dimet~l-4-heptEmoneto the filtrateand stir vigor-

ouslywith a mechanicalstirrer.

f. W-h the organic phase with 50ml of water (Note1).

g. Wash the organicphase again with 20 ml of 5% tartaric

acid and then with 40 ml of 5$ ELXCAsolution containingsmall Smounta

of ~ NeOH. Diacmiwashinga.

h. ~lute the organicphase to 15 ml with the extractant

and measure the Se7- gamma activity.

i. Chemicalyield is determinedby compting the peak area

of Se75 -n the orgdc phaae from ample with that of se75 in a known

amount of carier.

NOTE :

1. If the two layera do not aeperate quickly,add small

amounta of formic acid.

PL5LthumMetal(84)

Procedureused in:

Methcii:

Type of nuclear bombardment:

Procedureby:

Chemicalyield of carrier:

Separationtime:

1.6

Activation~yais

Ion exchangeaad precipitation

Se74(n,~)Se7s

Morris and Killick(84)

. 8@

Severalhours

Degree of purification:

Equipmentneeded:

1.6.1 Procedure:

a. Irradiate

@a at a flux of l&2

Separationfactor of seleniumfrom telluriumof greater than104.

Staatid

aemple (041 g) in nuclear reactor for E?

n/cnF.sec.

36

b. Trarmfer sample to a flask attachedto a water-cooled

reflux condenserthat contains10 mg of Te and 15 mg of Se carriers.

Wash samples into flaak with ~ HNOS and add 5 ml of ~ HC1 and

dissolvethe platinm by wamhg at 600C on a water bath.

c. Remove HN03 by addjng ~ HC1 and heating. Cool, aud

transfer to a centrifuge tube. Dilute to 35 JIJ with water. Place

in an ice bath and add 1 g N&Cl to precipitate (~)2 PtCle. Allow

to stand 10 minutes and centrifuge.

d. Separate supernateinto cleea centrifugetube. Pass

S02 rapidly through solctionfor 2 to 3 minutes. Centrifugeand

va9h with water.

e. Dissolve Se and Te in ndnbnnn amount of ~ llNOg. Add

2 mg of Pd carrier and dilute to 20 ml with &.O. Heat to boiling.

Neutralizewith ~ NaOH .md add 1 ml more of the reagent. Add 1 to

2 mg Fe+s carrier dropwisewith stirring. Centrifugeand discard

the precipitationof Fe(OH)S.

f. Add 1 ml of 6~ EIN03to supernateand then add, with

stirring,1 ml of 1$ solution of dimethylglyoximein 95$ C2HSOH.

Allow to stand 10 minutes and filter through a Whatman No. 41

paper. Evaporatethe filtrateto dryness, adding a few drops

of lC$ KI during the evaporation;then dissolvewith 5 ml of

12M HClc—

g. Pass the solutionthrough a deaciditeFF (100-203

mesh, preequilibratedwith la HC1) anion-exchangecolumn (equiva-

lent to Resin Dowex 1-x8), 5 cm in len@h and 1 cm in diameter.

Elute with 20 ml of 31jHC1 into a 50-ml glass centrifugetube.

h. Add 20 ml of l% HC1 to the eluate in a centrifuge

tube. Paas S02 through the solutionto precipitatethe Se and

centrifuge, Wash with water and dissolve in minimum quantity

of @ HIT03. Evaporate to dryness. Add 1 ml of 6M NaOH, then—

20 ml of @ HC1, and boil for 15 minutes. After the addition

of 10 ml of 2C$ solutionof hydroxylsminehydrochloride,centri-

fuge, then discard supemate. Wash the Se with water and then

with C2HSOH. Transfer the precipitatewith a little C2H50H to

a weighed aluminum countingtray, and dry at 100”C. Weigh as

Se and determinethe chemicalyield.

37

2.1

2.2

Arsenic

Procedureused h:

Method:

Type of nuclear

Procedureby:

bombardment:

Separationtime:

Chemicalyield of

Decontamination:

Equipment needed:

carrier:

Preparationof radioactivetracers

Volatill.tyand precipitation

194-Mev deuterom

H. Hopkins,Jr., reportedby

Mei*e(8’)

45 minutes

> 90%

RadiocheH&caUy pure by afactor of - 100

Standard

2.1.1 Procedure:

a. Dissolve

b. Add5mg

move excess HN03.

Aa metal in mintium 10~ HN03.

Se carrier, evaporate to near dryness to re-

c. Make up to 3 ml with ~ HC1, add N& OH,HCl until Se

darts to precipitatefrm hot Bolution.

a. Add 1 ml ~ ICI,heat 5 minutes, centrifugeoff mixture

of Se and 12.

em Dissolvewith a udnlnmm amount of fuming HTJOS,repeat

precipitation.

Bismuth Metal(81)

Procedu uged in:

Method:

Type of nuclear bombardment:

Procedureby:

Sepexationtime:

Chemicalyield of

Decontamination:

Equipmentneeded:

terrier:

Preparationof radioactivetraceri3

Volatilityaud precipitation

184” cyclotron (388-MeveLphas;3~Mev protone; 194-Mev deuterons)

Goeckermen,reportedby Mei*e(8’)

1 hour

- 9&

_ 104 from fission and spallationproducts

Stsnhrd

38

2.2.1

and Te,

still.

taining

disti~

Procedure:

a. To aliquot of BN03 solutionof target, add 10 mg Se

10 ml concentratedHBr, sad 0.5 ml liquid Brz in a glass

Uging en air stream, distill into a centrifugetube con-

5 ml saturatedBr2 water, which is cooled in en ice bath,

until only a >ml residue remains.

b. Keep at ice temperatureand reduce to Se (red)with

S02 or N&OH.HCl. Add aerosol and centrifuge.

c. Dissolve Se in a few drops of concentratedHN09, add

10 ml concentratedHC1 and reduce with S02 in am ice bath. Centri-

fuge with aerosol.

d. Repeat SeBr4 distillationand Se precipitationsas

often as necessuy for desiredpurity.

e. PrecipitateSe, filter, wash three times with 5 ml

~0, three times with 5 ml ethyl alcohol, three times with 5ml

ether, dry 10 minutes at llOUC. Weigh as Se.

2.3 Uranyl Nitrate(36)

Procedure uBed in:

Method:

Type of nuclear bombardment:

Procedureby:

Separationtime:

Chemicalyield of

Decontamination:

Equipmentneeded:

carrier:

2.3.1 Procedure:

Preparationof radioactivetracers

Solvent extraction

Neutron - 5min. atpower level of 1000 Kw.

Kuroda, reportedby Meinke(36)

19 min.

70%

Radiochemicallypure by gammaspectroscopy

Neutron source and stand-laboratoryequipment

a. Di8BOlVe 30-50 mg irradiateduanYl nitrate in 20 ti

of concentratedHBr containingw 1 mg of Te and 30 mg of Se carriers.

Pass air stream through the solutionfor 5 minutes to expel fission

gases.

39

b. Extract Se with ~ ml of 2,6-dlmethyl-&heptanonefor

@ sec. and discard aqueousphase,

c. Shake the organicphase for 30 secondswith 10 ti 10$

tartaric scid; repeatwith 10 ml of ~ NsOH. Dlscti aqueous

phases.

d. Wash the organicphase by shaking for 30 secondswith

30 ml of a solution5$ in EDTA and 5$ in sodium tartrate. Then

shake with 20 ml of water.

e. Strip Se from the organicphase by shaking for 20

seconds each with three 10-ml portions of C12-saturatedvater.

f. To the aqueousphase add a

and 6 ml of 12 NsOH md shake.

g. Add 20 drOpS Of COnC. HN03

few mg of iodide carder

to acidify the solution.

h. Add dropwise a 2* solutionof hydroxylamhe hydro-

chlorideuntil brown color of iodine appears.

i. Extract iodinewith successive5-ml portions of C-

bon tetrachlorideuntil the color of the organicphase disappe=s.

J. The organicphase Is discardedeach time and the radle

chemicalPurim of the aqueous phase is tested by gemma spectroscopy.

3.1 Fission-Roduct Solutions(82)

Procedm used in:

Method:

Type of nuclear

Procedureby:

bombardment:

Chemicalyield of c~er:

Sepmation the:

Degree of purification:

Equipment reqtired:

Determinationof fission-product activitiesin plantprocess solutions.

Volatility and precipitation

Uranium fission

Glendeninsnd Winsberg(83)

M

1 hour

Excellent

Standexdlaboratoryequip-ment

a. Place

still and add 2 ml

3.1.1 Procedure:

not more than 5 ml of seanple(Note1) in a glass

of Se csxrier =d 10 ml of cone. HBr. Distill

40

the Se into ~ HL of water contained in a 50-ml centrifugetube

placed in an ice bath. Continuethe distillationuntil no more

than 2 to 3 ml of Bolutlonremains in the distillationflask

(Note2).

b. Paas S02 rapidly (Note 3) through the distillate (in

an ice bath) until the red precipitateof Se is coagulated(2-3

minutes), centrifuge,and wash with 10 ml ofwater (Note 4).

c. Dissolve the Se by heatingwith 5 to 10 drops of cone.

SNO~; evaporatenearly to dryness; and take up In 10 UL of cone.

HC1. Place in an ice bath and precipitatethe Se with S02 as in

step b,

d. Repeat step c.

e. Transfer the Se with 5 to 10,ml of water onto a

weighed paper (Note 5) in a small Hirsch Ihumel and filterwith

suction. Wash three times with 5 ml of ethanol,and three times

with 5 ml of ether. Dry at 11O”C for ten minutes,weigh as elemen-

t~ se; and munt.

NOTES:

1. If the sample containsa large amount of nitrate, add

the Se carrier and boil down to about 1 niibefore distilling

with HBr.

2. The distillationof Se is practicallycompleteat this

point. The solutionshould not be taken to drynees.

3. A rapid stream of S02 hastens precipitationand aids

in coagulation.

4. A few drops of aerosol solutionprevents scum fomna-

tion and aids in centrifugation.

5. The filter paper is washed with ethanol end ether, and

dried under the conditionsof the procedurebefore weighing.

3.2 IrradiatedPolyphenyls(85)

Proceduremed in: Iktemination of fissionproduct activitiesin irradiatedpolyphenylB

Method: Volatility and precipitation

41

Type of nuclear bombardment: Uranium fission

Frocedum by: Felber and Koch(85)

Chemlcel yield of carrier: Wgojt

Ilsgreeof purification: Good

Equipment required: Stand-d laboratoryequipment

3.2.1 Procedure:

a. Aliquots of samples (not exceeding15 grams) and

carriersare dissolvedin cone. PN03, and perchloricacid is

added to deccunposethe organicmaterial. S-ampleis taken to

fumes of HC104.

b, Sulfur is sep=ated from the solutionby precipi-

tation of B8S04.

c. Seleniumis separatedby reductionwith S02. The

Se precipitateis dissolvedin cone. HBr containingsulfuric

and nitric acids. SeBr4 is distilledin the presence of air

into water. Seleniummetal is precipitatedby reductionwith

S02.

d. Selenium Is distilleda second time and the metal

Is repeatedlyprecipitated,and then weighed as the metal smd

the Se75 is counted.

4.1 Szilard-ChalmersReaction

Procedureused in: Carrier-freeseparationofSeleniumradioactivity

Radioelement(s)separated: Se=(25m), Se-(5~),

Se=(17m), and Se75(121d)

Procedureby: Gest and Edwexda(&)

4.1.1 Procedure:

a. One gram of ammonium Eelenite (Note1) irradiated

for 30 minutes.

b. After irradiationdissolve selenitein 31 HC1 and

extractwith CS2 (Notes2 end 3).

c. Evaporate CS2 fraction to dryness and the take up

Se in cone. HNO~.

42

N~S:

1. Anmonl.umseleniteprepmed by neutralizingSe02 solu-

tions with Ii&OH and crystallizingwith acetone.

2. 2C$ of the seleniumactivity faund in CS2 fraction.

3. In a second method, a 62 HC1 solution of the irradi-

ated selenltewas filtered through a fine sinte~d-glaas

filter. Much of the radioactivitywas depositedon the

filter. 28$ of the original aelenlumradioactivityremoved

by passing boiling cone. EUT09through the filter.

h.2 Ikuteronlkmbardmentof an Arsenic Tex@

ProcedureUBed in: Preparationof carrier-freeselenium

Method: Bombardmentof arsenic tiget

Type of bombardment: lg-Mev deuteronbombardmentwith 60” cyclotron

Time of sepantion: 3-4 hours

Chemicalyield: 80-95$

Procedureby: Gartison,Maxwell and Hamilton(8)

Ikgree of purification: At leaat factor of 103

Equipment required: Standard laboratoryequipment

4.2.1 Proceduxe:

a. Dissolve arsenic-powdertarget in aqua regla.

b. Add ~ HC1 to destroy excess HNOS and adjust acidity

to yJ.

C. AddlOmg of

S02; approtitely 95% of

d. Diesolvethe

tellurousacid

Se carries.

Te precipitate

and precipitateTe with

in cone. BIT03and repre-

cipitatefrom 31 HC1 in presence of As holdback caxrier.

e. Repeat Step d two more times.

f. Wash the Te precipitate,dissolve in minimum volume

of 16x HN03, and transfer to distillingflask.

g. Add 141 EBr dropwise whil-ea

is bubbled through the solution at 200eC.

in a water trap cooled w~th ice.

stream of N2 carrier gas

Collect the distill.ate

43

h. Remove the HBr with HN03 and evaporateto dryness on

40 mg of NaCl in the presence of excess EC1. Th&actltity, presu-

mably as aelenate,is quantitativelysoluble in 5 ml of water.

4.3 Uraulum FYssion

Procedureused in:

Type of bombardment!

Reikloelement(s)sep=ated:

Procedure by:

Eegree of purification:

Equipment required:

Prep=ation of carrier-freeseleniumradioactitities

Neutron source

Se7m(17.5 s), Se7m(3.9 m),

Se=m(57.5 s), See1(18.2m).

Kuroda, reportedbyhleitie(36)

Radiochemicallypure by gaunnaspectroscopy

Standard

4.3.1 Procedure:

a. Put irradiateduranyl nitrate (40-50mg) into a centri-

fuge tube. Add 2 or 3 drops of concentratednitric acid md 4ml of

water. Pass air streem through solutionfor 5 minutes.

b. Add- 1 mg of Te c~er and 20 ml of cone. HBr.

c. Extract seleniumwith 5 ml of 2,6-dimethyl-4-heptanone

for 40 seconds and discard aqueousphase.

d. Shake the organicphsae for 30 secondswith 10ml l@

tartsricacid; repeatwith 10 ml of lliNaOH. Discard aqueous

phases.

e. Wash the orgaaicphase by shaking for 30 secondswith

30 ml of a solution 5$ in EETA and 5$ in sodium tartrate,then

shakewith 20 ml of water.

f. Strip seleniumfrom the organicphase by shaking for

20 seconds each with three 10 ml portions of C12 - saturatedwater.

g, To the aquecrusphase add a few mg of iodide carrier

and 6 ml of lIJNaOH and shake.

h. Add 20 drops of cone. HN03 to acidify the solution.

i. Add dropwisea 2C$ solutionof hydroxyleminehydro-

chlorideuntil brown color of iodine appears.

J. Extract iodinewith successive5-ml portions of c-

bon tetrachlorideuntil the color of the organicphase d.isappeus.

k. The organicphase is discardedeach time, end the

mdiochemical purity of the aqueousphase is tested by gamma spec-

troscopy.

5. CARRIXR PIUZPARATIONAND STANDARDIZATION

1. Prepamti on

Dissolve 16.4 grams of seleniousacid in water and dilute to one

Ilter (1 ml ==lCkug

2. Standardization

Se).

Pipet 5 ml of carrier solutionInto a beaker. Add 100 ml of 5!

HC1. Add 10 ml of a 25$ hydroxyleminehydrochloridesolution. Heat

for 1-2 hours at 90°C. Filter through a pretreatedslntezwdglass

crucible, wash with water, and then with alcohol. Dry in an oven

105-110°Cfor 20 ndnutes. Cool and weigh as selenlummetal.

Mg S+l =wt. of Se metal

5ml

NOTES:

1. If the red selenium

the crystallinegrey-black

is overheatedit may convert

variety. This may result in

et

to

high results due to the occlusion of water and oxidation.

2. To prevent oxidationthe precipitatecan be dried

in an atxnosphereof carbon dioxide.

45

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

I-2.

13.

14.

15.

Strominger,D., Hollander,J.

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—. —.

MONOGRAPHS IN THE RADIOCHEMISTRY AND THETECHNfQUE SERIES

RADIOCHEMICAL

Copiesofthefollowingmonographsare availablefrom theClearinghouseforFedeml ScientificandTeohnioalfnforma-tlon,NationalBureauofStandards,U.S.DepartmentofCom-merce, Springfield,Va.

Alumtium and Gallium,NAS-NS-3032, $0.50

Americium and Curium, NAS-NS-3006,$0.75

Antimony,NAS-NS-3033, $0.50

Arserdc,NAS-NS-3002 (Rsv.)1965$1.00Astatine,NAS-NS-3012, $0.50

Barlurn,Calcium,and strontium,NAS-NS-3010,$1.25

Be@ium, NAS-NS-3013, $0.75

Cadrolum, NAS-NS-3001, $0.75Carbon, Nitrogen, and @gen, NAS-NS-

3019, $0.50Cesium, NAS-NS-3035, $0.75Chromium, NAs-Ns-3007, (Rsv.)1964 $0.7scobalt, NAS-NS-3041, $1.00Copper, NAS-NS-3027, $0.75Fluorine, Cblor5ne, Bromine, and Iodine,

NAS-NS-3005. $0.50Franoium, NAS-NS-3003, $0,50Germanium, NAS-NS-3043, $0,50Gold, NAS-NS-3036, $0,50Ind.ium, NAS-NS-3014, $0,50Iridium, NAS-NS-3045, $0.50Iron, NAS-NS-3017, $0,50Lead, NAS-NS-3040, $1.75Magnesium,,NAS-NS-3024, $0,50

_ese, ”NAS-NS-301B,$0.50Mercury, NAS-NS-3026, $0.50Molybdenum, NAS-NS-3009, $0.50

Nickel,NAS-NS-3051, $0,50Niobium and Tantalum,NAS-NS-3039, $0.75

Osmium, NAS-NS-3CM6, $0.50Palladium,NAS-NS-3052, $0.75Phosphome, NAS-NS-3056, $0.50

PIMnum, NAS-NS-3044, $0.50Polonium,NAS-NS-3037, $0.75Potassium,NAS-NS-3043, $0.50Protactinium,NAS-NS-3016, $1.00

Radium, NAS-NS-305’7,$2.25Rare Earths— Scandium,Yttrium,and Ac-tirdum,NAS-NS-3020, $3.00

Rare Gases, NAS-NS-3025, $0.75Rhenium, NAS-NS-302S, $0,50

Rhodium, NAS-NS-300S, (Rev.)1965$1.00

Rubidium, NAS-NS-3053, $0.50Ruthenium, NAS-NS-3029, $1.00Selenium, NAS-NS-3030, (Rsv.)1965 $1.00Sfliccm, NAS-NS-3049, $0.50Sflver, NAS-NS-3047, $0.75&xUum, NAS-NS-3055, $0.50Sulfur, NAS-NS-3054, $0.50Technetium, NAS-NS-3021, $0.60Tellurium, NAS-NS-3038, $0,50Thorhun, NAs-Ns-3004, $0.75Tin,NAS-NS-3023, $0.75TiWunl, NAS-NS-3034, $0.50Tranecurium Elements, NAS-NS-3031P

$0.50Tungsten, NAS-NS-3042, $0.50Umrdlml, NAS-NS-3050, $3.50Vanadium, NAS-NS-3022, $0.75Zblc, NAS-NS-3015, $0.75Ziroordum and Hafniurn, NAS-NS- 3011,

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Applications of Computers to Nuclear andRadiochemiatry, NAS-NS-3107, $2.50

Application of Instillation Techniques toBadiochemical Separations, NAS-NS-3108, $0.50

Detection and Measurement of Nuclear Ra-diation, NAS-NS-3105, $1,50

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Separations by Solvent Extnmtion with Tri-n-octylphospbine Oxtde, NAS-NS- 3102,$0.75