A simple and versatile PSA system for heavy metal determinations

Abstract

An easy to build potentiometric stripping analysis system for heavy metal determinations (Zn, Cd, Pb, Cu) is described which reaches good sensitivity and precision. Main components are an IBM compatible computer, an ADDA-conversion card and two selfmade electrodes, so it can be realized for one tenth of the price of complete commercial systems. A graphite pencil lead covered with a Hg-film is used as working electrode and a Ag/AgCl electrode as a combined reference/counter electrode. Reproducibility and calibration measurements are reported, heavy metal determinations on soil samples are compared with AAS results.

Pencil Graphite Electrodes: A Versatile Tool in Electroanalysis

“…The electrical contact between the electrode and the instrument was realized through a metal wire wrapped at the other end of the pencil lead. Bund et al [ 70 ] described a PGE developed by connecting a silver wire to the graphite lead and the whole system was introduced through a silicon rubber into a glass tube so that the lead can be pushed out and its surface renewed by polishing before each recording. For clozapine analysis in human plasma a microsystem consisting of a micropipette tip was obtained by inserting the electrodes, with PGE as working electrode, through a septum [ 71 ].…”

“…PGEs were pretreated potentiostatically by maintaining the electrode in an electrolyte for more than 30 s at a selected potential higher than 1.3 V [ 9 , 53 , 55 , 56 , 60 , 70 , 99 – 101 , 105 , 192 , 193 ] or by scanning the potential at a given scan rate, for a certain number of cycles within a large potential range [ 2 , 57 , 58 , 61 , 69 , 103 , 106 , 188 , 194 ]. Some papers report a comparison between the two mentioned activation procedures and depending on the electrochemical performances obtained for the investigated analyte one of them was selected; for example, chronoamperometric activation of PGE was used for alkylphenols [ 50 ] and tannic acid [ 51 ] analysis and cyclic voltammetric activation of PGE for dopamine [ 21 ] and bisphenol A [ 54 ] detection.…”

“…Different metals or metal containing compounds can be attached to bare or already modified PGEs surface either as thin films [ 28 , 64 ] or as different nanostructures (NS). For example, in situ generated Hg-film PGEs were used for the potentiometric stripping analysis of Cu(II), Pb(II), Cd(II), and Zn(II) from river sediments with comparable results with those obtained by atomic absorption spectrometry [ 70 ] or for anodic stripping voltammetric monitoring of Cu(II) levels in the Prut-river during a period of three years [ 199 ].…”

Influence of pencil lead hardness on voltammetric response of graphite reinforcement carbon electrodes

“…The literature describes many applications of GRC electrodes: for determining the titratable acidity in vinegar [3,4]; in abrasive stripping voltammetry [5]; in determination of ozone [6], dopamine [7], caffeine [8], trepibutone [9], uric acid [10]; in simultaneous determination of nitrite, dopamine and serotonin [11]; as substrate for mercury [12] and bismuth [13] films in trace metal determination; in liquid chromatography for determination of phenols [14]; applied with modified surface for determination of 2,4-dichlorophenol [15]; in voltammetry of microparticles [16]; in studies of copper-chelating properties of flavonoids [17]; in studies of DNA hybridization [18][19][20][21]; for discrimination of herpes type [22]; in detection of hepatitis B virus DNA [23,24] and in studies of interaction between DNA and lycorine [25], arsenic trioxide [26] and cis-DDP [27] molecules.…”

Applicability of potentiometric stripping analysis to the speciation of lead–humic acid complexes using potassium permanganate as oxidant

“…It is advantageous when redox couples exhibit sluggish electrochemical charge transfer kinetics but rapid chemical charge transfer 34 and can be implemented by using straightforward equipment such as a three-electrode cell, a highimpedance operational amplifier, an x-t recorder and a potentiostat. [35][36][37] In addition, times can be measured more readily and precisely than micro currents and no potential ramp need be used (in contrast to ASV), which results in lower instrumental costs. Some workers have reported that PSA is much less affected by surface-active substances 33,[38][39][40] than are other stripping techniques, such as ASV.…”