Research Article Development of Chromium(III - downloads

Hindawi Publishing CorporationJournal of ChemistryVolume 2013 Article ID 142752 6 pageshttpdxdoiorg1011552013142752

Research ArticleDevelopment of Chromium(III) Selective Potentiometric Sensorby Using Synthesized Triazole Derivative as an Ionophore

Pankaj Kumar1 Harish Kumar Sharma2 and Kamaal G Shalaan2

1 Department of Chemistry College of Engineering Studies University of Petroleum and Energy Studies UttarakhandDehradun 248007 India

2Department of Chemistry Maharishi Markandeshwar University Mullana Haryana Ambala 133203 India

Correspondence should be addressed to Pankaj Kumar pkumarddnupesacin

Received 29 June 2012 Accepted 28 August 2012

Academic Editor Arturo Espinosa

Copyright copy 2013 Pankaj Kumar et al is is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

A new poly(vinyl chloride) membrane based electrochemical sensor containing synthesized triazole compound that is bis-(4-N-amino-5-mercapto-124-triazol-3-yl)alkane (BAMTA) as an electroactive material was prepared and investigated as achromium(III) selective sensor e optimum composition of the best performing membrane contained triazole sodiumtetraphenylborate (NaTPB) nitrophenyl octyl-ether (NPOE) and polyvinyl-chloride (PVC) in the ratio 10 2 50 38ww esensor exhibited near Nernstian slope of 198 plusmn 02mVdecade of activity in the working concentration range of 10 times 10minus5 minus 10 times10minus1M It displayed a stable potential response in the pH range 34ndash52 e sensor exhibited a fast response time of less than 10 sand could be used for at least 6 weeks without any considerable divergence in potentials e proposed sensor showed very goodselectivity over most of the common cations including Li+ K+ Na+ Ni2+ Co2+ Cu2+ Sr2+ Ba2+ Cs+ Pb2+ Zn2+ Mg2+ Cd2+ Al3+Fe3+ and La3+ It could be employed successfully for the determination of Cr(III) ion activity in electroplating and leather tanningindustry wastes

1 Introduction

Chromium nds its widespread use in steel manufacturingleather tanning wood treatment electroplating paint andpigmentmetal nishing and alloymanufacturing industriesChromium is essential for carbohydrate and fat metabolismIts deciency may lead to diabetes and cardio-vasculardiseases e estimated safe and adequate daily dietaryintake for chromium in adults is 50ndash200120583120583g per day [1 2]On the other hand it is well known for its carcinogeneffects Its high concentration can also cause epigastria painnausea vomiting diarrhea and hemorrhage Due to the vitalimportance of Cr(III) in complex biological systems andindustrial systems environmental and industrial samplesthe development of a new selective and sensitive methodfor its quick estimation is a challenging goal Althoughsophisticated analytical techniques like atomic absorptionspectrometry (AAS) -ray uorescence (RF) high per-formance liquid chromatography (HPLC) and inductivelycoupled plasmamdashatomic emission spectroscopy (ICP-AES)

have been generally employed for the trace level determina-tion of metals yet these techniques are disadvantageous interms of routine analysis and cost Potentiometricmonitoringoffers many advantages such as simple instrumentationspeed and ease of preparation low cost online monitoringwide dynamic range good selectivity and nondestructiveanalysis Due to these advantages a number of ion-selectiveelectrodes have been reported in the recent past and the listis continuously growing tremendously

Different types of electroactive materials have beenused by researchers to develop chromium(III) ion-selectiveelectrodes Some of them are 4-dimethylaminoazoben-zene [3] 1-(2-(1H-imidazole-1-yl)-1-(4-methoxyphenyl)ethylidene)-2-phenyl hydrazine [4] 1-[(2-hydroxy ethyl)amino]-4-methyl-9H-thioxanthen-9-one [5] 4-amino-3-hy-drazino-6-methyl-124-triazin-5-one [6] 2-acetylpyridine[7] N-(1-thien-2-ylethylidene)benzene-12-diamine [8]5-amino-1-phenyl-1H-pyrazole-4-carboxamide [9] tributylphosphate [10] N-(acetoacetanilide)-12-diaminoethaneand NNprime-bis(acetoacetanilide)-triethylenetetramine [11]

2 Journal of Chemistry

glyoxal bis(2-hydroxyanil) [12] oxalic acid bis(cyclohexy-lidene hydrazine) [13] tri-o-thymotide [14] Aurin TCA[15] and p-(4-Acetanilidazo)calix[4]arene [16]

Diverse ionophores have been introduced for the fabrica-tion of cation selective electrodeswhich include crown etherscalixarenes porphyrins metal chelates and ligands Schiff rsquosbases and macrocyclic compounds ese compounds area category of supramolecular receptors exhibiting rigid cav-ities generally in a molecular recognition A large varietyof cation substrates can be complexed by such heterocyclicstructures due to the various available cavity sizes and thisproperty of these compounds has been largely exploited forthe development of a number of cation selective electrodesis efficiency depends on the lipophilicity conformationalexibility and high mobility Triazole which is appropriatelydesigned exhibits a large variety of functions for exampleinclusion compounds selective complexing agents for metalions and catalysts

Here we report for the rst time a new highly selec-tive and a sensitive Cr(III) electrode based on a synthe-sized triazole derivative that is Bis-(4-N-amino-5-mercapto-124-triazol-3-yl)alkane as an excellent neutral carrier forchromium(III) ions is suitability has been further con-rmed as the PVCmembrane electrodes containing triazolesshown a highly selective behavior towards Cr(III) ions In thepresent study various experimental conditions such as thepercentage weight composition of the membrane ingredientsand concentration of the internal solution of the developedelectrode have been optimized to obtain better detection limitas well as working concentration range

2 Experimental

21 Reagents For the development of ion-selective elec-trodes high molecular weight PVC (polyvinylchloride) wasused as mechanical support and it was purchased from(Fluka Switzerland) were used without any further treat-ment Triazole derivate was synthesized and characterizedby following the procedure reported elsewhere [17] Tetrahydrofuran (THF) as solvent was purchased from (MerckIndia) and Cr(NO3)3 NiCl2 Ca(NO3)2 CoCl2 KCl MnCl2LiNO3 AgNO3 and Pb(NO3)2 from (RANKEM India)NaCl ZnCl2 CuCl2 from (CDH India) HgCl2 CdCl2 andEDTA from (QULIKEMS India) Metal ion solutions wereprepared in doubly distilledwater and standardized by appro-priate methods Plasticizers nitrophenyl octyl ether (NPOE)dibutylbutyl phosphonate (DBBP) dibutyl phthalate (DBP)tris-(2-ethylhexyl)phosphate (TEP) and tri-butyl phosphate(TBP) and 1-chloro naphthalene (1-CN) were obtained from(Mobil USA) and sodium tetraphenylborate (NaTPB) from(BDH UK) Metal salt (nitrate and chloride) solutions wereprepared in doubly distilled water and standardized wherevernecessary e chemical characterization of the synthesizedcompoundwas carried out by the spectroscopicmethodseobtained results were similar to those already reportedeseadditives affected the performance of membrane almost ineach case Varying amounts of these compounds were addedto the ionophore PVC and THF solution prior to pouring it

into the acrylic ringse ratio of membrane ingredients wasoptimized aer a good deal of experimentation

Best efforts were made to prepare a membrane thatgenerates reproducible and stable potentials Conditioningof all the membranes was done with 01M Cr3+ solutione minimum time required for conditioning was 48 hoursotherwise the membranes produced unstable potentials epotential measurements were carried out using the followingcell setup at 25 plusmn 01∘C Internal reference electrode Ag-AgClInternal solution 01M chromium nitratePVC mem-branetest solutionExternal reference electrode Ag-AgCle concentration of the metal ion in the test solutionsvaried from 10 times 10minus6 to 10 times 10minus1M All the standardmetal ion solutions were prepared by serial dilution with10 times 10minus1Mas stock solution At equilibrium themembranepotential is mainly dependent on the concentration of thetarget ion outside the membrane and is described by theNernst equation Each solution was stirred and potentialreadings were recorded ese potential values were plottedagainst negative logarithmic values of chromium ion activityto obtain the standard calibration curve

22 Equipments ELICO LI 120 pH meter was used asmillivoltmeter and a digital pH meter from (FLORA) tocalculate the pH value of solutions prepared Silvermdashsilverchloride electrodes were used as reference electrodes

23 Preparation of Membranes e ionophore triazole de-rivative anion excluder sodium tetraphenylborate (NaTPB)plasticizers were taken in constant amounts in the ratio10 2 50 38ww with an appropriate amount of THF sol-vent e mixture was vigorously shaken and aer removingthe air bubbles it was poured into ringsmade of polyacrylatewhich were placed on a smooth glass plate e solution wasallowed to evaporate in closed environment at room tem-perature Aer 48 hours transparent membranes of 5mmdiameter were cut attached to a pyrex glass tube with the helpof araldite and immersed in different metals ion solutionsfor equilibration e ratio of membrane ingredients wasoptimized aer a good deal of experimentation to providemembranes which generate reproducible results low noiseand stable potentials e membranes prepared above wereequilibrated inmetal ion solutions of constant concentrationsfor different periods of time Satisfactory equilibration wasachieved with 01M metal ion solutions in a contact timeof 2 days Plasticizers are known to improve the responseof membrane by providing a smooth surface high dielectricconstant homogeneity and improving of the membrane bycreating liquid channels in the hydrophobic environmentunder the membrane us the response of the membraneimproves a lot On the other hand anion excluder that isNaTPB supervises the activity of anion and ensures thatgenerated partial gradient must be dependent only on theconcentration difference of the metal ion present on bothsides of the membrane e effects of solvent mediatorsand anion excluder were investigated by adding differentamounts of these compounds to the membrane solutionbefore pouring it to acrylic rings

Journal of Chemistry 3

3 Results and Discussion

31 Selection of the Membrane In preliminary experimentsthe synthesized ionophore was used as a neutral carrier toprepare PVC based membranes and was tried to determinevarious metal ions A number of membrane electrodes wereprepared and conditioned in 01M solution of differentmetalion solutions namely Li+ K+ Na+ Ni2+ Co2+ Cu2+ Sr2+Ba2+ Cs+ Pb2+ Zn2+ Mg2+ Cd2+ Al3+ Fe3+ and La3+ionsolutions for 2-3 days e best potential response of theelectrode was recorded for Cr3+ ions while all other ionsexhibited lower potential response or no response at allCr(III) ions could interact with the ionophore to form a bettercomplex with the electron rich cavity in the comparison ofthe bivalent cations is may be due to its higher charge andsuitability which facilitated its attachment to the ionophorein a better way Further the rapid exchange kinetics ofthe resulting ligand-metal ion complex is responsible forthe selective behavior of the ionophore towards Cr3+ incomparison to the other trivalent metal ions ereforethis membrane was used to develop a chromium(III) ions-selective electrode It is well known that some additives likeanion excluders are useful as these compounds enhance thesensitivity and selectivity of cation selective membrane byreducing its resistance [18] Also in case of PVC basedneutral carriermembranes plasticizers if compatible with theionophore can provide a smooth surface to the membraneand thus enhance the response characteristics Althoughthe role of plasticizers is not very rmly established tilldate but it is assumed that these additives enhance thehomogeneity of the PVC based membranes and provideliquid channels within the membrane which facilitates themovement of charge carriers which ultimately improvesthe response time and the sensitivity of the membranes Itcan also improve the dielectric constant of the polymericmembrane and also themovement of ionophore and itsmetalcomplex [19 20] erefore the effect on the performance ofthe membrane aer the addition of anion excluder sodiumtetraphenylborate (NaTPB) and plasticizers DBP DBBPTEP TBP 1-CN and NPOE was also studied e ratio ofmembrane ingredients time of contact and concentration ofequilibrating solution was optimized so that the membranecould develop reproducible noiseless and stable potentialsMembrane to membrane reproducibility was assured bycarefully following the optimum conditions of fabrication

32 Working Concentration Range and Slope e potentialresponse of the electrochemical cells with 01MCr3+ as inter-nal solution inside the indicator electrode was determinedin the range 10 times 10minus6 to 10 times 10minus1MCr3+ solution anddepicted in Figure 1 e best working concentration rangeobtained for NPOE that is 10 times 10minus5 ndash 10 times 10minus1M with aslope of 198mV decade of activitye effect of the additionof other plasticizers that is DBP DBBP TEP TBP and 1-CN was not signicant on the response properties of themembrane Further as the response characteristics of anymembrane depend on the amount of ionophore the effectof changing quantity of ionophore was also studied If the

140

120

100

80

60

40

20

0

0

pp

t (m

V)

7 6 5 4 3 2 1

F 1 Potentiometric response of the PVC membrane sensorbased on triazole

amount of ionophore is less than the above-mentioned ratioit affects the working concentration range adversely althoughthe effect on slope is not considerable If the amount isincreased further it shows no improvement in any of thecharacteristics of the electrode

33 Effect of the Concentration of Internal Solution on theResponse of Sensor e performance of the electrode wasanalyzed by using three different concentrations of Cr(III)ions as the internal solution that is 10 times 10minus1 10 times 10minus2and10 times 10minus3M e best results regarding working concentra-tion range and slope were obtained with an internal solutionof activity 10 times 10minus1M erefore an internal solution ofCr3+ ion activity 10 times 10minus1M was used throughout thestudies

34 Potentiometric Selectivity e inuence of interferingions on the response behavior of ion-selective membraneelectrodes is usually described in terms of selectivity coeffi-cientse xed interference method and the mixed solutionmethod are among the most commonly used to determinethe selectivity coefficient of the sensors However thesemethods suffer some limitations if ions of unequal chargesare involved us in this work we followed the matchedpotential method (MPM) which is totally independent of theNicolsky-Eisenman equation and also the varying charge ofinterfering ions According to MPM primary ions (A) in aspecied activity are added to a reference solution containingxed concentration of primary ions and the potential changeis recorded In a separate experiment interfering ions (B) aresuccessively added to an identical reference solution untilthe measured potential matched the one obtained beforeby adding primary ions A value of selectivity coefficientequal to 10 indicates that the sensor responds equally tothe primary as well as an interfering ion However a valuesmaller than 10 indicates that the membrane sensor is


T 1 Potentiometric selectivity coefficient values (KpotCr3+ sdotE) (inter-

fering ions B) observed for the fabricated Cr3+ selective electrodeusing matched potential method

Interfering ion B Matched potential methodLi+ 10 times 10minus3

Na+ 32 times 10minus3

K+ 70 times 10minus3

Ni2+ 49 times 10minus3

Co2+ 90 times 10minus3

Cu2+ 11 times 10minus2

Mg2+ 41 times 10minus2

Pb2+ 62 times 10minus2

Sr2+ 16 times 10minus2

Ba2+ 81 times 10minus2

Zn2+ 27 times 10minus3

Cd2+ 39 times 10minus2

Mn2+ 87 times 10minus3

La3+ 10 times 10minus3

Fe3+ 68 times 10minus3

Al3+ 27 times 10minus3

responding more to the primary ion than an interferingion and in such a case the sensor is said to be selectiveto the primary ion over interfering ions Further smallerthe selectivity coefficient higher is the selectivity order eMPM selectivity coefficient 119870119870MPM

AB is given by the resultingprimary ion to interfering ion activity (concentration) ratio

119870119870MPMAB =10076491007649119886119886A minus 119886119886A 10076651007665119886119886B (1)

e values of 119886119886A and 119886119886A were taken to be 10 times 10minus3

and 5 times 10minus3M whereas the value of 119886119886B was experimentallydetermined e experimental conditions employed and theresulting values are given in Table 1 It is clear from theobtained data that selectivity coefficient values are muchsmaller than 1 for almost all the mono- di- or trivalentcaions Hence the electrode shows good selectivity towardschromium(III) ions over other cations

35 pH Range pH dependence of the proposed ion-selectiveelectrode was studied over the pH range 20ndash80 at the 10 times10minus3M Cr3+ concentration aer adjusting the pH of thesolutions with HNO3 and NaOH It is clear that the potentialremained constant in the pH range (34ndash52) which canbe considered as the working pH range of the proposedsensor (Figure 2) Above this pH range a sharp decrease inpotentials may be attributed to the hydrolysis of chromiumions and formation of some soluble or insoluble hydroxylcomplexes while for pH values below this range the decreasein potentials may be due to the inuence of hydrogen ionsux

36 Potentiometric Titration e sensor was tried success-fully for the end point determination in the potentiometric

2 25 3 35 4 45 5 55 6100

150

200

250

300

350

Po

ten

tial

(m

V)

pH

Working pH range 34ndash52

F 2 Effect of pH on the cell potential of electrode

140

120

100

80

60

40

20

0

po

t (m

V)

0 05 1 15 2

vol of EDTA

F 3 Potentiometric plot for the titration ofCr(III) 10times 10minus2M(10mL) against EDTA (10 times 10minus1M)

titration of Cr3+ against EDTA solution A 10mL of 10 times10minus2M solution of Cr3+ was titrated against 10 times 10minus1MEDTA solution at pH 44 e conventional sigmoid shapeplot was obtained and the sharp break point corresponds tothe stoichiometry of Cr(III)-EDTA complex and indicates theend point of titration (Figure 3) [21]

37 Analytical Application e proposed sensor has beensuccessfully used for determining chromium ions in six realsamples ree were obtained from a nearby electroplatingindustry at the interval of seven days and another three froma lather tanning industry in a similar fashion e sampleswere collected ltered and stored in plastic bottles andwere analyzed within 2 hours aer the collection eir pHwas adjusted at 40 by using 01MHNO3 and hexamineese samples were pretreated to convert Cr(VI) to Cr(III)if present any by following the reported method [22] eobtained data indicates that the amount of chromium deter-mined in effluent by using the proposed sensor is in close


T 2 Cr(III) concentration as determined by the proposed potentiometric sensor as well as by atomic absorption spectrophotometer

Sample no pH found pH adjusted at Cr(III) activity as determined by the proposed sensor (ppm)lowast(Standard deviation plusmn 01)

Cr(III) activity as determined byAAS (ppm)

1 26 30 56 572 22 30 65 643 26 30 69 704 44 30 140 1385 52 30 136 1376 58 30 118 116lowastAll the observations are the average value for four readings recorded for the same sample

T 3 Comparison of proposed Chromium(III) selective electrode with some of the earlier reported electrodes

Ionophore used Working concentrationrange (M)

Detection limit(M)

WorkingpH range Interference Response

time (s) Reference no

4-dimethylaminobenzene 166 times 10minus6ndash10 times 10minus2 80 times 10minus7 30ndash55 Cu2+ Ag+ Fe3+ 10 [3]119873119873119873119873-bis(acetoacetanilide)Triethylenetetramine 83 times 10minus7ndash10 times 10minus1 63 times 10minus7 20ndash55 No interference 22 [11]

Glyoxal bis(2-hydroxyanil) 30 times 10minus6ndash10 times 10minus2 63 times 10minus7 27ndash65 Zn2+ 20 [12]

Oxalic acid bis(cyclohexylideneHydrazide 10 times 10minus7ndash10 times 10minus2 63 times 10minus7 17ndash65 Cd2+ Ni2+ 20 [13]

Tri-o-thymotide 40 times 10minus6ndash10 times 10minus1 20 times 10minus7 28ndash51 Na+ Cd2+ 15 [14]p-(4-acetanilidazo)calix[4]arene 98 times 10minus7ndash10 times 10minus1 73 times 10minus7 28ndash57 No interference 14 [15]

Aurin TCA 70 times 10minus6ndash10 times 10minus1 Not mentioned 35ndash65 Na+ Zn2+ Pb2+ 10 [16]1-[(2-hydroxy ethyl) amino]-4-methyl-9H-thioxanthen-9-one 32 times 10minus7ndash10 times 10minus1 16 times 10minus7 48ndash63 NM 10 [5]

4-amino-3-hydrazino-6-methyl-124-triazin-5-one 10 times 10minus6ndash10 times 10minus1 58 times 10minus7 27ndash66 NM 8 [6]

N-(1-thien-2-ylethylidene)benzene-12-diamine 10 times 10minus6ndash10 times 10minus1 70 times 10minus7 30ndash66 NM 15 [8]

BAMTA 10 times 10minus5ndash10 times 10minus1 86 times 10minus6 34ndash52 No interference 10 Proposed work

agreement with that determined by the atomic absorptionspectrophotometer (Table 2)

It is important to mention that the proposed sensorexhibits superior results than the existing sensors for theselective uantication of chromium(III) ions this sensorshows better selectivity [3 12ndash14 16] and better responsetime [8 11ndash15] Its working pH range is also comparable tomost of the listed sensors (Table 3)

4 Conclusion

A new poly(vinyl chloride) membrane containing bis-(4-N-amino-5-mercapto-124-triazol-3-yl)alkane as a membranecarrier was used to fabricate a chromium(III) selectiveelectrode e optimum composition of the best performingmembrane contained triazole NaTPB NPOE PVC in theratio 10 2 50 38 (ww) is electrode exhibited a nearNernstian slope of 198 plusmn 02mVdecade of activity in theworking concentration range of 10 times 10minus5 ndash 10 times 10minus1Mis sensor works nicely in the pH range 34ndash52 as thereis no change in observed potential of a xed concentration

of Cr(III) is electrode showed very good selectivity overmost of the common cations which are generally presentin real samples It could be used for the determination ofCr(III) concentration in the industrial waste samples as wellas an indicator electrode in the potentiometric titration ofCr(III) ion against EDTA solution e results show that theproposed sensor can be considered as a good addition in theexisting list of Cr(III) selective sensors

References

[1] National Research Council Recommended Dietary AllowanceNational Academy Press Washington DC USA 10th edition1989

[2] D E Kimbrough Y Cohen A M Winer L Creelman andC Mabuni ldquoA critical assessment of chromium in the en-vironmentrdquo Critical Reviews in Environmental Science andTechnology vol 29 no 1 pp 1ndash46 1999

[3] A Abbaspour and A Izadyar ldquoChromium(III) ion-selectiveelectrode based on 4-dimethylaminoazobenzenerdquo Talanta vol53 no 5 pp 1009ndash1013 2001


[4] A Abbaspour M Refahi A Khala-Nezhad N S Rad andS Behrouz ldquoCarbon composite-PVC based membrane coatedplatinum electrode for chromium determinationrdquo Journal ofHazardous Materials vol 184 no 1ndash3 pp 20ndash25 2010

[5] M Ghaedi A Shokrollahi A R Salimibeni S Noshadiand S Joybar ldquoPreparation of a new chromium(III) selectiveelectrode based on 1-[(2-hydroxy ethyl) amino]-4-methyl-9H-thioxanthen-9-one as a neutral carrierrdquo Journal of HazardousMaterials vol 178 no 1ndash3 pp 157ndash163 2010

[6] H A Zamani G Rajabzadeh andM R Ganjali ldquoHighly selec-tive and sensitive chromium(III) membrane sensors based on4-amino-3-hydrazino-6-methyl-124-triazin-5-one as a newneutral ionophorerdquo Sensors and Actuators B vol 119 no 1 pp41ndash46 2006

[7] W Zhou Y Chai R Yuan J Guo and X Wu ldquoOrganicallynanoporous silica gel based on carbon paste electrode forpotentiometric detection of trace Cr(III)rdquo Analytica ChimicaActa vol 647 no 2 pp 210ndash214 2009

[8] M R Ganjali P Norouzi F Faridbod M Ghorbani and MAdib ldquoHighly selective and sensitive chromium(III) membranesensors based on a new tridentate Schiff rsquos baserdquo AnalyticaChimica Acta vol 569 no 1-2 pp 35ndash41 2006

[9] H A Zamani G Rajabzadeh M Masrornia A DejbordM R Ganjali and N Sei ldquoDetermination of Cr3+ ions inbiological and environmental samples by a chromium(III)membrane sensor based on 5-amino-1-phenyl-1H-pyrazole-4-carboxamiderdquo Desalination vol 249 no 2 pp 560ndash565 2009

[10] A Zazoua R Kherrat M H Samar et al ldquoCharacteri-zation of TBP containing polysiloxane membraneinsulatorsemiconductor structures for hexavalent chromium detectionrdquoMaterials Science and Engineering C vol 28 no 5-6 pp1014ndash1019 2008

[11] A K Singh V K Gupta and B Gupta ldquoChromium(III)selective membrane sensors based on Schiff bases as chelatingionophoresrdquo Analytica Chimica Acta vol 585 no 1 pp171ndash178 2007

[12] M B Gholivand and F Sharifpour ldquoChromium(III) ion selec-tive electrode based on glyoxal bis(2-hydroxyanil)rdquoTalanta vol60 no 4 pp 707ndash713 2003

[13] M B Gholivand and F Raheedayat ldquoChromium(III) ionselective electrode based on oxalic acid bis(cyclohexylidenehydrazide)rdquo Electroanalysis vol 16 no 16 pp 1330ndash13352004

[14] V K Gupta A K Jain P Kumar S Agarwal and GMaheshwari ldquoChromium(III)-selective sensor based on tri-o-thymotide in PVC matrixrdquo Sensors and Actuators B vol 113no 1 pp 182ndash186 2006

[15] R K Sharma and A Goel ldquoDevelopment of a Cr(III)-specicpotentiometric sensor using Aurin tricarboxylic acid modiedsilicardquo Analytica Chimica Acta vol 534 no 1 pp 137ndash1422005

[16] P Kumar and Y B Shim ldquoChromium(III)-selective electrodeusing p-(4-Acetanilidazo)calix[4]arene as an ionophore in PVCMatrixrdquo Bulletin of the Korean Chemical Society vol 29 no 12pp 2471ndash2476 2008

[17] M Al-Amin and M R Islam ldquoSynthesis of some bis-triazolederivatives as probe for cytotoxicity studyrdquo Bangladesh Journalof Pharmacolog vol 1 pp 21ndash26 2006

[18] V K Gupta R Prasad P Kumar and R Mangla ldquoNewnickel(II) selective potentiometric sensor based on 571214-tetramethyldibenzotetraazaannulene in a poly(vinyl chloride)matrixrdquoAnalytica ChimicaActa vol 420 no 1 pp 19ndash27 2000

[19] V K Gupta R N Goyal S Agarwal P Kumar andN BachhetildquoNickel(II)-selective sensor based on dibenzo-18-crown-6 inPVC matrixrdquo Talanta vol 71 no 2 pp 795ndash800 2007

[20] T Hiroyuki G Takuya and I Yasuhiko ldquoConcentration- andconcentration ratio-de-pendent selectivity coefficients for ion-selctive electrodesrdquo Analytica Chimica Acta vol 73 no 2 p328 1974

[21] V K Gupta A K Jain L P Singh U Khurana and P KumarldquoMolybdate sensor based on 5101520-tetraphenylporphyrin-atocobalt complex in a PVC matrixrdquo Analytica Chimica Actavol 379 no 1-2 pp 201ndash208 1999

[22] M Pettine L Campanella and F J Millero ldquoReduction of hex-avalent chromium by H2O2 in acidic solutionsrdquo EnvironmentalScience and Technology vol 36 no 5 pp 901ndash907 2002

Submit your manuscripts athttpwwwhindawicom

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2013


Carbohydrate Chemistry

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom


Analytical ChemistryVolume 2013

ISRN Chromatography


Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawi Publishing Corporation httpwwwhindawicom Volume 2013

The Scientific World Journal

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2013


CatalystsJournal of

ISRN Analytical Chemistry


ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013


Advances in

Physical Chemistry

ISRN Physical Chemistry


SpectroscopyInternational Journal of


ISRN Inorganic Chemistry



Journal of

Chemistry


Inorganic ChemistryInternational Journal of


International Journal ofPhotoenergy


Analytical Methods in Chemistry

Journal of

Volume 2013

ISRN Organic Chemistry



Journal of

Spectroscopy


glyoxal bis(2-hydroxyanil) [12] oxalic acid bis(cyclohexy-lidene hydrazine) [13] tri-o-thymotide [14] Aurin TCA[15] and p-(4-Acetanilidazo)calix[4]arene [16]

Diverse ionophores have been introduced for the fabrica-tion of cation selective electrodeswhich include crown etherscalixarenes porphyrins metal chelates and ligands Schiff rsquosbases and macrocyclic compounds ese compounds area category of supramolecular receptors exhibiting rigid cav-ities generally in a molecular recognition A large varietyof cation substrates can be complexed by such heterocyclicstructures due to the various available cavity sizes and thisproperty of these compounds has been largely exploited forthe development of a number of cation selective electrodesis efficiency depends on the lipophilicity conformationalexibility and high mobility Triazole which is appropriatelydesigned exhibits a large variety of functions for exampleinclusion compounds selective complexing agents for metalions and catalysts

Here we report for the rst time a new highly selec-tive and a sensitive Cr(III) electrode based on a synthe-sized triazole derivative that is Bis-(4-N-amino-5-mercapto-124-triazol-3-yl)alkane as an excellent neutral carrier forchromium(III) ions is suitability has been further con-rmed as the PVCmembrane electrodes containing triazolesshown a highly selective behavior towards Cr(III) ions In thepresent study various experimental conditions such as thepercentage weight composition of the membrane ingredientsand concentration of the internal solution of the developedelectrode have been optimized to obtain better detection limitas well as working concentration range

2 Experimental

21 Reagents For the development of ion-selective elec-trodes high molecular weight PVC (polyvinylchloride) wasused as mechanical support and it was purchased from(Fluka Switzerland) were used without any further treat-ment Triazole derivate was synthesized and characterizedby following the procedure reported elsewhere [17] Tetrahydrofuran (THF) as solvent was purchased from (MerckIndia) and Cr(NO3)3 NiCl2 Ca(NO3)2 CoCl2 KCl MnCl2LiNO3 AgNO3 and Pb(NO3)2 from (RANKEM India)NaCl ZnCl2 CuCl2 from (CDH India) HgCl2 CdCl2 andEDTA from (QULIKEMS India) Metal ion solutions wereprepared in doubly distilledwater and standardized by appro-priate methods Plasticizers nitrophenyl octyl ether (NPOE)dibutylbutyl phosphonate (DBBP) dibutyl phthalate (DBP)tris-(2-ethylhexyl)phosphate (TEP) and tri-butyl phosphate(TBP) and 1-chloro naphthalene (1-CN) were obtained from(Mobil USA) and sodium tetraphenylborate (NaTPB) from(BDH UK) Metal salt (nitrate and chloride) solutions wereprepared in doubly distilled water and standardized wherevernecessary e chemical characterization of the synthesizedcompoundwas carried out by the spectroscopicmethodseobtained results were similar to those already reportedeseadditives affected the performance of membrane almost ineach case Varying amounts of these compounds were addedto the ionophore PVC and THF solution prior to pouring it

into the acrylic ringse ratio of membrane ingredients wasoptimized aer a good deal of experimentation

Best efforts were made to prepare a membrane thatgenerates reproducible and stable potentials Conditioningof all the membranes was done with 01M Cr3+ solutione minimum time required for conditioning was 48 hoursotherwise the membranes produced unstable potentials epotential measurements were carried out using the followingcell setup at 25 plusmn 01∘C Internal reference electrode Ag-AgClInternal solution 01M chromium nitratePVC mem-branetest solutionExternal reference electrode Ag-AgCle concentration of the metal ion in the test solutionsvaried from 10 times 10minus6 to 10 times 10minus1M All the standardmetal ion solutions were prepared by serial dilution with10 times 10minus1Mas stock solution At equilibrium themembranepotential is mainly dependent on the concentration of thetarget ion outside the membrane and is described by theNernst equation Each solution was stirred and potentialreadings were recorded ese potential values were plottedagainst negative logarithmic values of chromium ion activityto obtain the standard calibration curve

22 Equipments ELICO LI 120 pH meter was used asmillivoltmeter and a digital pH meter from (FLORA) tocalculate the pH value of solutions prepared Silvermdashsilverchloride electrodes were used as reference electrodes

23 Preparation of Membranes e ionophore triazole de-rivative anion excluder sodium tetraphenylborate (NaTPB)plasticizers were taken in constant amounts in the ratio10 2 50 38ww with an appropriate amount of THF sol-vent e mixture was vigorously shaken and aer removingthe air bubbles it was poured into ringsmade of polyacrylatewhich were placed on a smooth glass plate e solution wasallowed to evaporate in closed environment at room tem-perature Aer 48 hours transparent membranes of 5mmdiameter were cut attached to a pyrex glass tube with the helpof araldite and immersed in different metals ion solutionsfor equilibration e ratio of membrane ingredients wasoptimized aer a good deal of experimentation to providemembranes which generate reproducible results low noiseand stable potentials e membranes prepared above wereequilibrated inmetal ion solutions of constant concentrationsfor different periods of time Satisfactory equilibration wasachieved with 01M metal ion solutions in a contact timeof 2 days Plasticizers are known to improve the responseof membrane by providing a smooth surface high dielectricconstant homogeneity and improving of the membrane bycreating liquid channels in the hydrophobic environmentunder the membrane us the response of the membraneimproves a lot On the other hand anion excluder that isNaTPB supervises the activity of anion and ensures thatgenerated partial gradient must be dependent only on theconcentration difference of the metal ion present on bothsides of the membrane e effects of solvent mediatorsand anion excluder were investigated by adding differentamounts of these compounds to the membrane solutionbefore pouring it to acrylic rings





140

120

100

80

60

40

20

0

0

pp

t (m

V)

7 6 5 4 3 2 1


























119870119870MPMAB =10076491007649119886119886A minus 119886119886A 10076651007665119886119886B (1)





2 25 3 35 4 45 5 55 6100

150

200

250

300

350

Po

ten

tial

(m

V)

pH



140

120

100

80

60

40

20

0

po

t (m

V)

0 05 1 15 2

vol of EDTA











Detection limit(M)













4 Conclusion



References

































ISRN Chromatography






CatalystsJournal of






Advances in

Physical Chemistry








Journal of

Chemistry







Journal of

Volume 2013




Journal of

Spectroscopy





140

120

100

80

60

40

20

0

0

pp

t (m

V)

7 6 5 4 3 2 1


























119870119870MPMAB =10076491007649119886119886A minus 119886119886A 10076651007665119886119886B (1)





2 25 3 35 4 45 5 55 6100

150

200

250

300

350

Po

ten

tial

(m

V)

pH



140

120

100

80

60

40

20

0

po

t (m

V)

0 05 1 15 2

vol of EDTA











Detection limit(M)













4 Conclusion



References

































ISRN Chromatography






CatalystsJournal of






Advances in

Physical Chemistry








Journal of

Chemistry







Journal of

Volume 2013




Journal of

Spectroscopy






















119870119870MPMAB =10076491007649119886119886A minus 119886119886A 10076651007665119886119886B (1)





2 25 3 35 4 45 5 55 6100

150

200

250

300

350

Po

ten

tial

(m

V)

pH



140

120

100

80

60

40

20

0

po

t (m

V)

0 05 1 15 2

vol of EDTA











Detection limit(M)













4 Conclusion



References

































ISRN Chromatography






CatalystsJournal of






Advances in

Physical Chemistry








Journal of

Chemistry







Journal of

Volume 2013




Journal of

Spectroscopy








Detection limit(M)













4 Conclusion



References

































ISRN Chromatography






CatalystsJournal of






Advances in

Physical Chemistry








Journal of

Chemistry







Journal of

Volume 2013




Journal of

Spectroscopy






























ISRN Chromatography






CatalystsJournal of






Advances in

Physical Chemistry








Journal of

Chemistry







Journal of

Volume 2013




Journal of

Spectroscopy










ISRN Chromatography






CatalystsJournal of






Advances in

Physical Chemistry








Journal of

Chemistry







Journal of

Volume 2013




Journal of

Spectroscopy

Documents

Research Article Development of Chromium(III - downloads