EXPERT-SYSTEM FOR THE VOLTAMMETRIC DETERMINATION OF TRACE-METALS .4. METHODS FOR SPECIATION OF CHROMIUM AND ARSENIC

A previously described expert system for the voltammetric determination of Cu, Zn, Cd, Pb, In, Ni, Co, Tl, Hg, V and Se (optionally also Te) is enlarged and improved by including methods for speciation of chromium and arsenic. Voltammetric procedures for the quantification of Cr(III), Cr(VI), As(III) and As(V) are considered, Cr(III) and As(V) being determined by the difference between total chromium and Cr(VI), and total arsenic and As(III) respectively. The techniques implemented are differential pulse polarography, differential pulse anodic stripping voltammetry, differential pulse cathodic stripping voltammetry and differential pulse adsorptive stripping voltammetry, using mercury drop electrodes and a rotating gold electrode. The expert system is developed using KES (knowledge engineering system).