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Automated Determination of Cu(II), Pb(II), Cd(II) and Zn(II) in Environmental Samples by Square Wave Voltammetry Exploiting Sequential Injection Analysis and Screen Printed Electrodes
Author(s) -
Ribeiro Luiz Fernando,
Masini Jorge Cesar
Publication year - 2014
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.201400462
Subject(s) - potentiostat , analytical chemistry (journal) , square wave , chemistry , anodic stripping voltammetry , deposition (geology) , flow injection analysis , voltammetry , electrode , detection limit , stripping (fiber) , electrochemistry , chromatography , materials science , sediment , voltage , geology , paleontology , physics , quantum mechanics , composite material
This paper describes the development of a methodology for quantification of Cu(II), Pb(II), Cd(II) and Zn(II) in waters and sediments by anodic stripping voltammetry (ASV) automated by Sequential Injection Analysis (SIA) using a graphite screen printed sensor modified with mercury. Determinations were made by standard addition automated by the SIA system. The limits of detection and quantification were, respectively, 1.3 and 4.3 µg L −1 for Cu(II), 1.4 and 4.6 µg L −1 for Pb(II), 0.6 and 1.8 µg L −1 for Cd(II) and 4.2 and 14 µg L −1 for Zn(II). These limits were obtained for a sample volume of 1000 µL, flow rate of 10 µL s −1 (during the deposition step), and utilizing 3 flow reversals (volume of reversion=950 µL), totalizing a deposition time of 315 s. The potentiostat worked synchronically with the SIA system applying the conditioning potential of −0.1 V vs. pseudo reference of Ag (100 s), deposition potential of −1.0 V for Cu(II), Pb(II) and Cd(II) or −1,3 V for Zn(II), square wave frequency of 100 Hz, potential step of 6 mV and pulse height of 40 mV. For quantification of Zn(II) in sediment extracts, deposition of Ga 0 on the working electrode was necessary to avoid the formation of intermetallic between Zn 0 and Cu 0 . The accuracy of the method was assessed by spike and recovery experiments in water samples which resulted recovery rates near 100 % of the spiked concentrations. Recoveries of concentrations in the certified sediment sample CRM‐701 undergoing the three steps sequential extraction procedure of BCR varied from 71.7 % for Zn(II) in the acetic acid extract to 112.4 % for Cu(II) in the oxidisable fraction, confirming that the standard addition approach corrected the matrix effects in the complex samples of sediment extracts.