EXPERT-SYSTEM FOR THE VOLTAMMETRIC DETERMINATION OF TRACE-METALS .3. METHODS FOR DETERMINING MERCURY, SELENIUM AND VANADIUM

A previously described expert system for the voltammetric determination of Cu, Zn, Cd, Pb, In, Ni, Co and Tl is enhanced and improved by means of the addition of methods for Hg, V and Se (optionally also Te). Special attention is paid to the determination of V, inside a wide concentration range, in different types of samples. The system guides the user in the choice of sample treatment and the most appropriate voltammetric procedure for the identification and the quantification of the trace metals. The techniques implemented are differential pulse polarography, anodic stripping voltammetry, cathodic stripping voltammetry and adsorptive stripping voltammetry, using mercury drop electrodes and a gold electrode (for the determination of Hg). For the identification and resolution of overlapping peaks (Cd and In), the system may call two external programs, written in turboBasic. Quantification is carried out by means of the multiple standard addition method, and the quality of the calibration plot is tested by several statistical validation tests. The expert system is developed using KES (knowledge engineering system).