Stripping Chronopotentiometry with Dry‐Preservable Supporting Electrolyte

Abstract

The determination of some toxic metals by stripping chronopotentiometry with a supporting solution having an unconventional composition has been investigated with the aim of using such components in disposable measuring cells preservable in dry state and quite ready for use, only needing addition of a small volume of sample. The new supporting solution is prepared with a solid strong acid, p-toluenesulfonic acid, in the place of the inorganic acids commonly used to improve the cation availability. The other components are, as usual, sodium chloride, which fixes the potential of the screen-printed silver ± silver chloride reference electrode, and mercury(II) chloride as the plating agent. This supporting solution has been tested in batch measurements with the mercury film glassy carbon electrode as well as with screen-printed carbon-ink electrodes, either with mercury film or bare. The physical shape of the mercury layer electrolytically deposited on screen-printed carbon-ink electrodes from a supporting solution containing 0.1 M p-toluenesulfonic acid and 0.1 M sodium chloride has been investigated by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) microanalysis. In chronopotentiometric stripping ptoluenesulfonic acid performs as well as the usual inorganic strong acids, particularly in terms of sensitivity. At 0.1 mol dm À3 it proved very suitable for the determination of toxic metals, in particular lead(II), at levels down to a few mg dm À3. The overall results appear promising and can open new avenues for preparing disposable cells for on-field stripping chronopotentiometric determination of toxic metals.

Catalytic Adsorptive Stripping Chronopotentiometric Determination of Hexavalent Chromium at a Silver Amalgam Film Electrode of Prolonged Application

“…In SCP various types of electrodes have been used, such as: glassy carbon electrodes 5, gold electrode 6, 7, carbon fiber 8, carbon paste electrode 9, 10, bismuth or antimony plated film electrodes 11–13 and screen‐printed carbon‐ink electrodes 14. The electrodes used most frequently are the mercury‐based electrodes 15–18.…”