Determination of arsenate and organic arsenic via potentiometric titration of its heteropoly anions.
Determination of arsenate based on its conversion to molybdoarsenate heteropoly anions followed by potentiometric titration is described. The titration is realized on the ion-pairing principle using cetylpyridinium chloride (or an analogous titrant containing a lipophilic cation), and is monitored by a carbon paste electrode, although other liquid-polymeric membrane-based electrodes can also be used. Calibration plots of the titrant end-point consumption versus concentration of arsenic were constructed and used to evaluate the content of arsenic in aqueous samples. The method could be applied in the analyses of samples with quite low arsenic content (amounts approximately 10 mug As in 50 cm(3) could be titrated). Organic arsenic was determined analogously after the Schöniger combustion of the sample and conversion of its arsenic to arsenate.
Metelka
R
R
Department of Analytical Chemistry, Faculty of Chemical Technology, University of Pardubice, Námesti Cs. Legii 565, 532 10 Pardubice, Czech Republic.
Slavíková
S
S
Vytras
K
K