Hindawi Publishing CorporationJournal of SpectroscopyVolume 2013, Article ID 548345, 6 pageshttp://dx.doi.org/10.1155/2013/548345

Research ArticleSpectrophotometric Determination of Iron(II) afterSolid Phase Extraction of Its 2,2′ Bipyridine Complex on SilicaGel-Polyethylene Glycol

Nahid Pourreza, Saadat Rastegarzadeh, Ali Reza Kiasat, and Hossein Yahyavi

Chemistry Department, College of Science, Shahid Chamran University, Ahvaz, Iran

Correspondence should be addressed to Nahid Pourreza; npourreza@yahoo.com

Received 27 June 2012; Accepted 28 August 2012

Academic Editor: Annemarie Wagner

Copyright © 2013 Nahid Pourreza et al.is is an open access article distributed under theCreativeCommonsAttribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

A new solid phase extraction procedure was developed for preconcentration of iron(II) using silica gel-polyethylene glycol (silica-PEG) as an adsorbent.emethod is based on retention of iron(II) as 2,2� bipyridine complex on silica-PEG.e retained complexis eluted by 1.0mol L−1 of sulfuric acid-acetonemixture (1:2) and its absorbance ismeasured at 518 nm, spectrophotometrically.eeffects of different parameters such as pH, concentration of the reagent, eluting reagent, sample volume, amount of adsorbent, andinterfering ions were investigated. e calibration graph was linear in the range of 1–60 ng mL−1 of iron(II). e limit of detectionbased on 3Sb was 0.57 ng mL−1 and relative standard deviations (R.S.D) for ten replicate measurements of 12 and 42 ng mL−1 ofiron(II) were 2.4 and 1.7%, respectively. e method was applied to the determination of of iron(II) in water, multivitamin tablet,and spinach samples.

1. Introduction

Nowadays, the extraction and determination of trace metalions fromdifferentmatrices have become of great importanceand have received more attention. Among heavy metals, ironin small amounts is an essential element for most life onEarth, including humans and animals. It is well known thatan iron de�ciency is the most common cause of anemia.On the other hand, too much iron can cause several healthproblems. High levels of iron are associated with an increasedrisk for cancer, heart, and liver diseases [1]. erefore irondetermination is of great interest and is crucial to developsimple, rapid, and efficient methods for monitoring iron inthe environment.

Modern instrumental methods including ICP-MS, ICP-AES, and AAS [2–8] have been used for the determinationof traces of metal ions in various media. However, spec-trophotometry and �ame atomic absorption spectrometry(FAAS) are the most available instrumental techniques inlaboratories but their sensitivity and selectivity are usu-ally insufficient for direct determination of elements at avery low concentration levels in real samples. erefore, a

separation/preconcentration step prior to the analysis isusually necessary for complex matrix environmental samples[7].

Solid phase extraction (SPE) has been used as a greattool for the separation and preconcentration of metal ions indifferent samples [8].e important advantages of solid phaseextraction such as �exibility, simplicity, being economical,high enrichment factors, low cost because of lower consump-tion and, being environment friendly have made SPE as anattractive technique for separation/preconcentration of heavymetal ions [9–11].e choice of appropriate sorbent for solidphase extraction is a critical parameter in order to obtain fullrecovery and high enrichment factor [12]. For this reasonintroducing new sorbent is still a challenge for analyticalchemists. Various sorption materials, such as functionalizedsilica or alumina [13, 14], carbonmaterials [15], naphthalene[16], and molecular-imprinted polymers (MIPs) [17] havebeen used for this purpose.

We have recently introduced silica gel-polyethylene gly-col (silica-PEG) as an adsorbent for preconcentration ofcobalt and nickel [18] followed by �ame atomic absorp-tion spectrometric determination. In this paper a different

2 Journal of Spectroscopy

aspect for using this adsorbent is presented and a newsolid phase extraction method for preconcentration of traceiron(II) prior to its determination by spectrophotometery isestablished. Iron(II) as 2,2� bipyridine complex was passedthrough a column containing silica-PEG. e retained com-plex was then eluted by sulfuric acid-acetone mixture (1 : 2)and its absorbance was measured at 518 nm by a spectropho-tometer.

2. Experimental

2.1. Instrumentation. A GBC model Cintra 101, UV-Visiblespectrophotometer (Sidney, Australia) was used for record-ing absorption spectra and absorbance measurements using1 cm glass cells. A digital pH-Meter model 632, Metrohm(Herisau, Switzerland), with a combined glass electrode, wasused for pH adjustments. A Tebazma vacuum pump (Tehran,Iran) was used for pumping the solutions.

2.2. Reagents. Analytical reagent-grade chemicals were used.A stock solution of 1000 𝜇𝜇gmL−1 Fe(II) was prepared bydissolving 0.7020 g of (NH4)2Fe(SO4)2.6H2O (Merck, Darm-stadt,Germany) inwater anddiluting to 100mL in a volumet-ric �ask. 6.4 × 10−4 mol L−1 of 2,2� bipyridine (Merck) wasprepared by dissolving 0.01 g in water and diluting to 100mLin a volumetric �ask. A phosphate buffer pH 8 was preparedby diluting 4.8mL phosphoric acid (Merck) to 250mL in avolumetric �ask and then adjusting its pH to 8 by adding1.0mol L−1 NaOH (Merck) and using a pH meter. Silica gel(Aldrich, USA, 70–270 mesh, 60Å, surface area > 500m2/g)was activated by treatment with 5mom L−1 HCl (Merck) anddried in vacuum at 120∘C. PEG was heated at 80∘C undervacuum for 30 min before use to remove traces of moisture.

2.3. Adsorbent Preparation by Immobilization of PolyethyleneGlycol on Silica Gel. An oven dried 250mL �ask equippedwith amagnetic stirrer was chargedwith dried activated silicagel (20 g) under nitrogen atmosphere. en freshly distilledSOCl2 (45mL) was added slowly to the �ask through anaddition funnel and the reaction mixture was stirred at roomtemperature. Evolution of copious amounts of HCl and SO2occurred instantaneously. Aer stirring for 4 h, the excessunreacted thionyl chloride was distilled off and the resultinggrayish silica chloride was �ame dried and stored in airtightcontainer before use.

To a well-stirred silica chloride (20 g) in dry CH2Cl2(40mL) PEG (10 g) was added dropwise under nitrogenatmosphere and at room temperature. HCl was instanta-neously evaluated. Aer stirring for 2 h, the obtained silica-gel-supported PEG was removed by �ltration. For elimina-tion of any additional PEG, the PTCwaswashed several timesby acetone (3–30mL). Silica-gel-supported PEG was dried ina vacuum oven overnight [19] and was used as an adsorbentin this work.

2.4. Recommended Procedure. 0.1 g of silica-PEG adsorbentwas placed in a glass tube (7 cm length and 7mm i.d) with

a very �ne bore and used as a preconcentration column.250mL of the solution containing 1–60 ng mL−1 of iron(II),2mL of 6.4 × 10−4mol L−1 2,2′ bipyridine, and 5mL ofphosphate buffer pH 8 was passed through the mini columnat a �ow rate of 10mL min−1. e adsorbed iron complexwas eluted with 2.0mL of 1.0mol L−1 of sulfuric acid-acetonemixture (1 : 2). e absorbance of the color complex wasmeasured at 518 nm. A blank solution was also run under thesame analytical conditions without adding any Fe(II).

2.5. Sample Pretreatments. e tap water sample was col-lected, acidi�ed, boiled, and �ltered. An aliquot of watersample was then treated under recommended procedure.

Fresh spinach sample was purchased from local marketAhvaz, Iran. It was washed thoroughly with water and driedin an oven at 100∘C for 7 h. It was then grinded to producea �ne powder. 12 g of this powder was placed in a porcelaincrucible and burned on a �ame until there was no fume. Itwas then placed in a muffle furnace at 600∘C for 5 h; 2mLof hydrochloric acid was added and boiled for 30 min. Itwas then �ltered and diluted to 50mL in a volumetric �ask.An aliquot of this solution was taken and treated under therecommended procedure.

e content of a multivitamin tablet was dissolved inwater; 5mL of hydrochloric acid 10% was added, �ltered,and diluted to 250mL in a volumetric �ask. An aliquot ofthis solution was taken and treated under the recommendedprocedure.

3. Results and Discussion

e PEG-graed silica particles are special type of branchedinorganic–organic copolymerwhich has polyether functionalgroups in the side chains that have been found to be stable toacid, base, high temperature, and oxygen. Its FT-IR spectrumshows the presence of OH and ethylene oxide groups onthe surface of the adsorbent. Our preliminary experimentsshowed that iron(II) as 2,2� bipyridine complex is retained bysilica-PEG.e 2,2� bipyridine complex is probably adsorbedthrough interaction with OH groups of the PEG. Since theamounts of the complex retained on the adsorbent is verysmall, the FT-IR spectrum aer loading the complex showsvery slight shis.

e absorption spectra of eluted complex from thecolumn by sulfuric acid-acetone mixture (Figure 1) showedthat maximum absorption takes place at 518 nm. ereforeabsorbance measurements were conducted at this wave-length. In order to achieve the highest performance forthe system, the effect of different parameters such as pH,concentration of the reagent, type and concentration ofeluent �ow, rates and amount of adsorbent on the solid phaseextraction were studied.

3.1. e Effect of pH. It has been mentioned in the literaturethat Fe(NN) chelates such as iron(II)-2,2� bipyridine complexare stable in the pH range of 3–10 [20]. erefore, thein�uence of the pH of the sample solution on the iron(II)

Journal of Spectroscopy 3

0

0.04

0.08

0.12

0.16

350 450

(a)

(b)

550 650

Ab

sorb

ance

Wavelength (nm)

F 1: Absorption spectra of (a) blank and (b) the eluted iron(II)as 2,2� bipyridine complex from the column.

0

0.1

0.2

0.3

2 4 6 8 10 12

Ab

sorb

ance

pH

F 2: Effect of pH on the absorbance of 50 ng mL−1 iron(II) as2,2� bipyridine complex aer desorption from the column.

ions as 2,2� bipyridine complex formation and hence itsadsorption on the silica-PEG adsorbent were studied. Forthis purpose, the pH value of a set of solutions (100mL)each containing 50 ngmL−1 of iron(II) was adjusted in therange of 4.0–10.0 by adding 0.1mol L−1 of HCl or NaOH.eobtained solutions were passed through the column, elutedby sulfuric acid-acetone mixture (1 : 2), and the absorbanceof the color complex was measured at 518 nm. Accordingto the results shown in Figure 2, the absorbance is constantover the pH range of 7.0–9.0. erefore, pH 8 was selected asoptimum for further work and 5mL of phosphate buffer pH8 was added to 100mL solutions to maintain this pH.

3.2. Effect of the Ligand Concentration. e effect of 2,2�

bipyridine concentrations on the absorbance of iron(II)-2,2�bipyridine complex eluted from the column was investigated.e results indicated that the absorbance was increasedup to a ligand concentration of 0.96 × 10−5mol L−1 andbecame almost constant above that (Figure 3). For thisreason, the present study was carried out with a ligand �nalconcentration of 1.28×10−5 mol L−1 as optimum value.us2.0mL of 6.40 × 10−4mol L−1 of 2,2� bipyridine was added to100mL solutions to maintain this concentration.

0

0.1

0.2

0.3

0 0.5 1 1.5 2 2.5 3

Ab

sorb

ance

Concentration of 2,2 bipyridine ×105 (mol L−1)

F 3: Effect of 2,2� bipyridine concentrations on the absorbanceof 50 ng mL−1 iron(II) as 2,2� bipyridine complex aer desorptionfrom the column.

T 1: Effect of different eluents on the absorbance of elutedFe(II)-2,2� bipyridine complex.

Eluent AbsorbanceAcetone 0.05DMSO 0.04H2SO4 (1mol L−1) 0.06HCl (1mol L−1) 0.03HNO3 (1mol L−1) 0.04Acetonitrile-H2SO4 (1mol L−1) 0.27Acetone-H2SO4 (1mol L−1) 0.78Acetonitril-HCl (1mol L−1) 0.18

3.3. Choice of Eluent. e other important factors whichcould affect the solid phase extraction procedure are the type,volume, and concentration of the eluent used for desorptionof metal complex from the adsorbent. In order to choose aproper eluent for the retained complex aer its extraction,the analyte was eluted with a series of selected eluents such asvarious inorganic acids, organic solvents, and their mixtures.e results of this investigation presented in Table 1 show thatamong different eluents used sulfuric acid-acetone mixtureprovided the highest absorbance for the eluted complex.erefore, this solution was chosen as an eluent for furtherinvestigations. e sulfuric acid concentration and H2SO4-acetone ratio were also optimized. According to the obtainedresults H2SO4 concentration of 1.0mol L−1 with a ratio of1 : 2 (H2SO4-acetone) was most suitable solvent for elutingthe complex from the column. e effect of eluent volumewas also investigated and 2mL of 1: 2 (H2SO4-acetone) wasfound to be adequate for the elution of retained iron(II)-2,2�bipyridine complex from the column.

3.4. e Effect of the Mass of Adsorbent. In order to test theeffect of the mass of adsorbent on quantitative retention ofiron(II)-2,2′ bipyridine complex different amounts of silica-PEG adsorbent were chosen and the experimental methodwas applied. e results showed that quantitative adsorptionfor the complex was obtained in the range of 0.05– 0.25 g ofadsorbent. Quantitative adsorption was not obtained when

4 Journal of Spectroscopy

the mass of extractant was smaller than 0.05 g. us 0.10 g ofsilica-PEG was selected for further studies.

3.5. e Effect of Flow Rate. In a solid phase extractionprocedure, the �ow rate of sample solution not only affectsthe recoveries of the analytes, but also controls the analysistime. erefore, the effect of sample solution �ow rate wasexamined under the optimum conditions by passing 100mLof sample solution through the minicolumn at different�ow rates. It was found that the retention of iron(II)-2,2� bipyridine complex was independent of �ow rate upto 10mLmin−1 and the absorbance of the solution wasdecreased slightly when the �ow rate was over 10mL min−1.erefore, a �ow rate of 10mL min−1 was employed in thiswork.

3.6. e Effect of Breakthrough Volume. In order to achievea high preconcentration factor, the breakthrough volumeof sample solution should be established. e effect ofsample volume on the adsorption of iron(II)-2,2� bipyridinecomplex was studied in the range of 100–500mL. Eachsolution contained same amount of Fe2+ (5 𝜇𝜇g) and theadsorption and desorption processes were performed underthe optimum conditions. e results showed that the Fe-2,2� bipyridine present in various volumes of solution wascompletely and quantitatively adsorbed on silica-PEG. eadsorption decreased at higher volumes.erefore, for deter-mination of trace quantities of Fe2+in samples, a samplevolume up to 500mL could be selected in order to increasethe preconcentration factor to 250. However, in order todecrease the analysis timewe used 250mL for the preparationof calibration curves for which a preconcentration factor of125 was employed.

3.7. Analytical Performance. e analytical characteristicsof the developed method such as the limit of detection,reproducibility, linear range, and correlation coefficient wereobtained by processing standard solutions under optimumconditions. A linear calibration graph was obtained for thedetermination of iron(II) under the proposed experimentalconditions. e data yielded a good linearity in the range of1–60 ng mL−1 with the equation of 𝐴𝐴 𝐴 𝐴𝐴𝐴1𝐴𝐴𝐴 + 𝐴𝐴𝐴2𝐴(𝐴𝐴 𝐴𝐴𝐴𝐴𝐴8𝐴)where A is the absorbance and C is the concentrationof iron(II) in ng mL−1. e limit of detection, de�ned asthe concentration of the analyte giving signals equivalent tothree times the blank standard deviation, was 0.57 ng mL−1and relative standard deviations (R.S.D) for ten replicatemeasurements of 12 and 42 ngmL−1 of iron(II) were 2.4 and1.7%, respectively.

3.8. Interference Studies. In order to investigate the selectivityof the solid phase extraction procedure, the in�uence ofdifferent ions which could interfere with the determinationof iron(II) in various environmental samples was studied. Forthis purpose constant amounts of iron(II) were taken withdifferent amounts of diverse ions and the general procedurewas followed. Any deviation of ±5% or more from the

T 2: e effect of different ions on the determination of50 ngmL−1 of iron(II).

Foreign ions Tolerance ratio [ion]/[Fe2+]K+, NO3

−, SCN−, NO2−, Br−, Mg2+, Cl− 1000

Pb2+, I−, Ca2+, F− 500Cd2+, Ba2+, Cr3+, (IV) 100Ni2+, Hg2+ 10Al3+, Cu2+, Co2+ 5

T 3: Determination of iron (II) in different samples.

Sample Added (ngmL−1) Founda (ngmL−1) Recovery (%)

Tap water— ND —4 3𝐴𝐴 ± 𝐴𝐴5 97.58 7𝐴8 ± 1𝐴𝐴 97.5

Multivitaminb— 7𝐴𝐴 ± 1𝐴𝐴 —10 17𝐴𝐴 ± 1𝐴𝐴 100.020 27𝐴5 ± 1𝐴2 99.5

Spinachc — 3𝐴𝐴𝐴 ± 𝐴𝐴8 —10 48𝐴2 ± 1𝐴3 97.9

a𝑥𝑥 ± 𝑥𝑥𝑥𝑥𝑥√𝑛𝑛 at 95 % con�dence (𝑛𝑛 𝐴 5).

bAmount of iron per tablet was 9.7mg.cAmount of iron was 40.6 𝜇𝜇g g−1 of spinach.ND: not detected.

absorbance value of the standard solution was selected asinterference. Results given in Table 2 show that the presenceof ma�or cations and anions has no signi�cant effect on thedetermination of iron(II) under selected conditions.

4. Applications

e developed method was applied to the determination ofiron in tap water, multivitamin tablet, and spinach samples,with satisfactory results (Table 3). e concentration ofiron(II) could not be determined in water due to its verylow concentration. ere was a good agreement between theadded and the recovered concentrations of the analyte. eobtainedmount of iron per tabletwas 9.7mg and the reportedvalue was 10.0mg which shows that there is good agreementbetween the two results.

5. Conclusion

Silica-PEG is a promising adsorbent which could be usedin different ways and this paper presents one of them.e method presented in this paper is highly sensitive andselective for the determination of trace amounts of Fe(II) byspectrophotometry. e detection limits achieved are betterthan or comparable to some of the previously reported works.A comparison of the proposed method with some of themethods reported in literature is given in Table 4. Moreover,the adsorbent is ecofriendly and stable for at least six month.

Journal of Spectroscopy 5

T 4: Comparison of the proposed method with some of themethods reported in literature.

System PFa DL(ngmL−1)

Breakthroughvolume (mL) Ref.

Amberite XAD-2000 50 0.32 250 [1]Modi�ed activatedcarbon 10 0.38 100 [2]

Flotation method 93 0.70 750 [3]BHAPN/SDS-alumina 63 2.60 500 [21]Naphthalene loaded withtetraoctylammoniumbromide

36 12.00 180 [16]

Silica-PEG 250 0.57 500 iswork

aPreconcentration factor.

Acknowledgment

e authors wish to thank Shahid Chamran University,Ahvaz, Iran, for �nancial support of this project (Grant1391).

References

[1] L. Elci, A. A. Kartal, and M. Soylak, “Solid phase extractionmethod for the determination of iron, lead and chromiumby atomic absorption spectrometry using Amberite XAD-2000 column in various water samples,” Journal of HazardousMaterials, vol. 153, no. 1-2, pp. 454–461, 2008.

[2] M. S. Karacan and N. Aslantaş, “Simultaneous preconcen-tration and removal of iron, chromium, nickel with N,N-etylenebis-(ethane sulfonamide) ligand on activated carbon inaqueous solution and determination by ICP-OES,” Journal ofHazardous Materials, vol. 155, no. 3, pp. 551–557, 2008.

[3] H. Karimi, M. Ghaedi, A. Shokrollahi, H. R. Rajabi, M. Soylak,and B. Karami, “Development of a selective and sensitive�otation method for determination of trace amounts of cobalt,nickel, copper and iron in environmental samples,” Journal ofHazardous Materials, vol. 151, no. 1, pp. 26–32, 2008.

[4] M. S. Karacan, N. Aslantaş, and H. G. Asian, “Enrichment andremoval of iron (II), copper (II) and strontium (II) ionswith sul-fonamides on activated carbon in environmental samples anddetermination by ICP-OES analysis,” Fresenius EnvironmentalBulletin, vol. 20, no. 5, pp. 1167–1173, 2011.

[5] M. Soylak and M. Tuzen, “Diaion SP-850 resin as a new solidphase extractor for preconcentration-separation of trace metalions in environmental samples,” Journal ofHazardousMaterials,vol. 137, no. 3, pp. 1496–1501, 2006.

[6] V. A. Lemos, R. S. da França, and B. O. Moreira, “Cloudpoint extraction for Co and Ni determination in water samplesby �ame atomic absorption spectrometry,” Separation and�uri�cation Technology, vol. 54, no. 3, pp. 349–354, 2007.

[7] V. Camel, “Solid phase extraction of trace elements,” Spec-trochimica Acta B, vol. 58, no. 7, pp. 1177–1233, 2003.

[8] Y. Cui, X. Chang, X. Zhu, N. Jiang, Z. Hu, and N. Lian,“Nanometer SiO2 modi�ed with 5-sulfosalicylic acid as selec-tive solid-phase extractant for Fe(III) determination by ICP-AES from biological and natural water samples,”MicrochemicalJournal, vol. 86, no. 1, pp. 23–28, 2007.

[9] N. Pourreza, M. R. Fathi, and Z. Ardan, “Flame atomic absorp-tion spectrometric determination of Cd(II), Ni(II), Co(II) andCu(II) in tea andwater samples aer simultaneous preconentra-tion of dithizone loaded on naphthalene,” Journal of the IranianChemical Society, vol. 7, no. 4, pp. 965–971, 2010.

[10] A. Safavi, N. Iranpoor, N. Saghir, and S. Momeni, “Glycerol-silica gel: a new solid sorbent for preconcentration and deter-mination of traces of cobalt(II) ion,” Analytica Chimica Acta,vol. 569, no. 1-2, pp. 139–144, 2006.

[11] N. Pourreza and K. Ghanemi, “Solid phase extraction of cad-mium on 2-mercaptobenzothiazole loaded on sulfur powder inthe medium of ionic liquid 1-butyl-3-methylimidazolium hex-a�uorophosphate and cold vapor generation-atomic absorptionspectrometric determination,” Journal of Hazardous Materials,vol. 178, no. 1–3, pp. 566–571, 2010.

[12] Z. Zang, Z. Li, L. Zhang et al., “Chemically modi�ed attapulgitewith asparagine for selective solid-phase extraction and precon-centration of Fe(III) from environmental samples,” AnalyticaChimica Acta, vol. 663, no. 2, pp. 213–217, 2010.

[13] S. Berijani, M.R. Ganjali, H. Sereshti, and P. Norouzi, “A selec-tive modi�ed nanoporous silica as sorbent for separation andpreconcentration of dysprosium in water samples prior to ICP-OES determination,” International Journal of EnvironmentalAnalytical Chemistry, vol. 92, no. 3, pp. 355–365, 2012.

[14] E. Naja�, O. Sadeghi, N. Tavassoli, P. Mirahmadpour, and H. R.L. Z. Zhad, “Flame atomic absorption spectrometric determi-nation of palladium in aqueous samples aer preconcentrationusing nanoparticles of 𝛾𝛾-alumina functionalized with pyridinegroups,” Analytical Sciences, vol. 26, no. 4, pp. 479–483, 2010.

[15] M. Soylak and Y. E. Unsal, “Chromium and iron determinationsin food and herbal plant samples by atomic absorption spec-trometry aer solid phase extraction on single-walled carbonnanotubes (SWCNTs) disk,” Food and Chemical Toxicology, vol.48, no. 6, pp. 1511–1515, 2010.

[16] N. Pourreza and H. Z. Mousavi, “Solid phase preconcentra-tion of iron as methylthymol blue complex on naphthalene-tetraoctylammonium bromide adsorbent with subsequent�ame atomic absorption determination,” Talanta, vol. 64, no.1, pp. 264–267, 2004.

[17] H. Yan, J. Qiao, Y. Pei, T. Long, W. Ding, and K. Xie, “Molecu-larly imprinted solid-phase extraction coupled to liquid chro-matography for determination of Sudan dyes in preservedbeancurds,” Food Chemistry, vol. 132, no. 1, pp. 649–654, 2012.

[18] N. Pourreza, J. Zolgharnein, A. R. Kiasat, and T. Dastyar, “Silicagel-polyethylene glycol as a new adsorbent for solid phaseextraction of cobalt and nickel and determination by �ameatomic absorption spectrometry,” Talanta, vol. 81, no. 3, pp.773–777, 2010.

[19] A. R. Kiasat and M. Zayadi, “Polyethylene glycol immobilizedon silica gel as a new solid-liquid phase-transfer catalyst forregioselective azidolysis of epoxides in water: an efficient routeto 1,2-azido alcohols,” Catalysis Communications, vol. 9, no. 10,pp. 2063–2067, 2008.

[20] S. Oszwałdowski and D. Marchut, “Characterization ofiron(II)(𝛼𝛼-diimine) chelates and their interactions withanionic, cationic and non-ionic micelles using the separation,spectrophotometric and computational methods,” AnalyticaChimica Acta, vol. 540, no. 1, pp. 207–219, 2005.

6 Journal of Spectroscopy

[21] M. Ghaedi, H. Tavallali, A. Shokrollahi, M. Zahedi, M.Montazerozohori, and M. Soylak, “Flame atomic absorp-tion spectrometric determination of zinc, nickel, iron andlead in different matrixes aer solid phase extraction onsodium dodecyl sulfate (SDS)-coated alumina as their bis (2-hydroxyacetophenone)-1, 3-propanediimine chelates,” Journalof Hazardous Materials, vol. 166, no. 2-3, pp. 1441–1448, 2009.

Submit your manuscripts athttp://www.hindawi.com

Chromatography Research International

Hindawi Publishing Corporationhttp://www.hindawi.com Volume 2013

Hindawi Publishing Corporationhttp://www.hindawi.com Volume 2013

Carbohydrate Chemistry

International Journal of

Hindawi Publishing Corporationhttp://www.hindawi.com

International Journal of

Analytical ChemistryVolume 2013

ISRN Chromatography

Hindawi Publishing Corporationhttp://www.hindawi.com Volume 2013

Hindawi Publishing Corporation http://www.hindawi.com Volume 2013Hindawi Publishing Corporation http://www.hindawi.com Volume 2013

The Scientific World Journal

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttp://www.hindawi.com Volume 2013

Hindawi Publishing Corporationhttp://www.hindawi.com Volume 2013

CatalystsJournal of

ISRN Analytical Chemistry

Hindawi Publishing Corporationhttp://www.hindawi.com Volume 2013

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation http://www.hindawi.com Volume 2013

Hindawi Publishing Corporationhttp://www.hindawi.com Volume 2013

Advances in

Physical Chemistry

ISRN Physical Chemistry

Hindawi Publishing Corporationhttp://www.hindawi.com Volume 2013

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttp://www.hindawi.com Volume 2013

ISRN Inorganic Chemistry

Hindawi Publishing Corporationhttp://www.hindawi.com Volume 2013

Hindawi Publishing Corporationhttp://www.hindawi.com Volume 2013

Journal of

Chemistry

Hindawi Publishing Corporationhttp://www.hindawi.com Volume 2013

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation http://www.hindawi.com Volume 2013

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttp://www.hindawi.com

Analytical Methods in Chemistry

Journal of

Volume 2013

ISRN Organic Chemistry

Hindawi Publishing Corporationhttp://www.hindawi.com Volume 2013

Hindawi Publishing Corporationhttp://www.hindawi.com Volume 2013

Journal of

Spectroscopy