DETERMINATION OF CHROMIUM(VI) IN RIVER WATER SAMPLES BY ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY

A simple analytical procedure, making use of the differential volatilities of the Cr-III and Cr-VI complexes with trifluoroacetylacetone, was developed for the determination of Cr-VI and total Cr in river water. It was based on a modification of the electrothermal atomic absorption spectrometric method with the addition of ammonium trifluoroacetylacetonate before starting the thermal programme. The analytical procedures developed was found to be applicable to the determination of 2-300 mu g l(-1) of Cr-VI in the presence of up to 300 mu g l(-1) of Cr-III. The precision was found to vary from 3.8 to 1.4% for 2.5-25 mu g l(-1) of Cr-VI, respectively. The applicability of the method developed to the analysis of river water samples was established by using parallel-method comparison, and no statistically significant difference between the results obtained and those of an ion-exchange resin method was observed.