Abstract
Chemically modified electrodes (CMEs) based on polymeric films of E-5-((5-isopropyl-3,8-dimethylazulen-1-yl) diazenyl)-1H-tetrazole (L) deposited on the surface of the glassy carbon electrode have been used for the recognition of heavy metal (Me) ions. The electrochemical study of L was done by three methods: differential pulse voltammetry (DPV), cyclic voltammetry (CV), and rotating disk electrode voltammetry (RDE). The CV, DPV, and RDE studies for L were performed at different concentrations in 0.1 M tetrabutylammonium perchlorate solutions in acetonitrile. The polymeric films were formed by successive cycling or by controlled potential electrolysis (CPE). The film formation was proven by recording the CV curves of the CMEs in ferrocene solution. The CMEs prepared at different charges or potentials were used for detection of heavy metal ions. Synthetic samples of heavy metal ions (Cd(II), Pb(II), Cu(II), Hg(II)) of concentrations between 10−8 and 10−4 M were analyzed. The most intense signal was obtained for Pb(II) ion (detection limit of about 10−8 M). Pb(II) ion can be detected by these CMEs in waters at such concentrations. The ability of the ligand L to form complexes with Pb(II) and Hg(II) ions was also tested by UV-Vis spectrometry. The obtained results showed the formation of Me(II)L2 complexes.
Highlights
Modified electrodes (CMEs) with complexing properties are alternative tools for the recognition of heavy metal ions which can be done by using very sensitive methods such as atomic absorption spectroscopy [1], emission spectroscopy [2], cold vapor atomic fluorescence spectrometry [3] and inductively coupled mass spectrometry [4]
Three methods have been used to study the electrochemical behavior of L: differential pulse voltammetry (DPV), cyclic voltammetry (CV) and RTDhEr.eeFimguerteho2dsshohwavsethbeeeDnPVusaenddtoCVstucduryvtehsereegleisctterroecdheamt oicxaidl abteiohnavainodr orefdLu:cDtioPnV, foCrVdaifnfderRenDtEc.oFnigceunretr2atsihoonws osfthLeiDn PthVeasnudpCpoVrtciunrgveeslercetgroisltyetreed(0a.1t oMxiTdBatAioPn/CanHd3CreNd)u.cTtihoen cfuorrvedsifafet rtehnetbcoottnocmen(tAra)taiornesthoefDLPiVn ctuhrevesus,papnodrtpinregseenletc2trmolayitnea(n0o.1diMc pTeaBkAsP(a/1C,Ha23)CfNor)
The electrochemical study of compound E-5-((5-isopropyl-3,8-dimethylazulen-1yl)diazenyl)-1H-tetrazole (L) in 0.1 M TBAP/CH3CN showed that a polymeric film which can complex the heavy metal cations can be obtained through the oxidative polymerization of L on a glassy carbon electrode
Summary
Modified electrodes (CMEs) with complexing properties are alternative tools for the recognition of heavy metal ions which can be done by using very sensitive methods such as atomic absorption spectroscopy [1], emission spectroscopy [2], cold vapor atomic fluorescence spectrometry [3] and inductively coupled mass spectrometry [4]. The CMEs can be prepared by physical absorption of several compounds or by electropolymerization of specific complexing monomers on solid electrodes. Each CME was taken out from the monomer solution, equilibrated and overoxidized in 0.1 M acetate buffer solution (pH = 4.5), according to previously described procedure [12,13] This L-CME was immersed for 15 min under stirring in a solution of heavy metal ions. This L-CME was immersed for 15 min un dofe1r1 stirring in a solution of heavy metal ions. After that the modified electrode having the accumulated ions was taken out, cleaned with distilled water and immersed in 0.1 M acettaakteenbuofufet,r csloelauntieodnw(pitHh =di4s.t5i)l,lewdhweraeteitr wanads pimolmareizreseddfoinr 30.m1 iMn toac−e1ta.2teVbaunfdferthseoslutrtipo-n p(ipnHg =cu4r.v5e),swwheerre irtewcoarsdpeodlabreiztwedefeonr −31m.2inVtoan−d1.+20V.8aVn.dTthe smtreipthpoindgucsuerdvefsowr reerceorgecnoitridoend wbaestwbeaesend−o1n.2thVeasntrdip+p0i.n8gVa.nTahlyesmiseothnoLd-CuMseEd cformrpecleoxginigtimonowdiafisedbaesleedctorondtehseusstirnipgptihneg DaPnValytescishonniqLu-eCaMvaEilcaobmlepilnexthinegpmotoednitfiioesdtaetlescotfrtowdaerse.using the DPV technique available in the potentiostat software
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