engleski

The influence of data treatment on the interpretation of experimental results in voltammetry

In order to realize the advantages provided by recent improvements in data storage and treatment, enabled by computerized instrumentation, a procedure for data treatment in voltammetry is proposed. It is shown how steps of this procedure are related and may affect the final conclusions. Examples of noise elimination, baseline subtraction and peak potential determination are given. Concentration of the reactant in the simulated sample determined by the standard addition method can be highly influenced by the choice of baseline type. Depending on the peak determination procedure used and after the statistical tests provided, in a 4 mol l-1 ionic strength media, models with three (b1 = 15.8 ą 0.9, b2 = 54.8 ą 4.7, b3 = 171.5 ą 3.8) and four (b1 = 14.5 ą 0.4, b2 = 74.3 ą 2.5, b3 = 129.2 ą 3.2, b4 = 11.2 ą 1.0) labile lead (II) chlorocomplexes were obtained. Appreciating the more precise results, four stability constants are proposed. It is the consequence of a detection limit shift towards noticing the existence of lower percentage of the highest order complexes present in the solution, obtained by more sophisticated software algorithms. The other evidence of the existence of the fourth complex is the statistically highly approved existence of four complexes in a 6 mol l-1 ionic strength media (b1 = 36 ą 2, b2 = 232 ą 39, b3 = 1360 ą 105, b4 = 436 ą 51), which is in accordance with the influence of ionic strength on the stability constants.

voltammetry; data treatment; stability constants

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