EXPERT SYSTEM FOR THE VOLTAMMETRIC DETERMINATION OF TRACE-METALS .2. METHODS FOR DETERMINING NICKEL, COBALT AND THALLIUM AT DIFFERENT CONCENTRATION RATIOS

An expert system for the voltammetric determination of Cu, Zn, Cd, Pb, In, Ni, Co and Tl was developed with special attention to methods for determining Ni, Co and Tl at different concentration ratios. The system guides the user in the choice of sample treatment, the most appropriate voltammetric procedure and the identification and determination of trace metals. The techniques implemented are differential-pulse polarography, anodic stripping voltammetry and adsorptive stripping voltammetry, using mercury drop electrodes. Only well known methods are recommended, with particular attention to standard methods. For the identification and resolution of overlapping peaks, the system may be used in conjunction with two external programs, written in turbo BASIC. Quantification is carried out by means of the multiple standard addition method, and the quality of the calibration graph is tested by several statistical tests performed by another external program. The expert system is developed using KES (Knowledge Engineering System).