Differential pulse cathodic stripping voltammetric determination of uranium with arsenazo-III at the hanging mercury dropping electrode

摘要

An accurate, inexpensive and less laborious controlled adsorptive accumulation of uranium(VI)-arsenazo-III on a hanging mercury drop electrode (HMDE) has been developed for uranium(VI) determination. The method is based upon the collection of uranium(VI)-arsenazo-III complex at pH 5-6 at the HMDE and subsequent direct stripping measurement of the element in the nanomolar concentration level. The cathodic peak current (i(p,c)) of the adsorbed complex ions of uranium(VI) was measured at -0.35 V vs. Ag/AgCl reference electrode by differential pulse cathodic stripping voltammetry (DP-CSV), proceeded by an accumulation period of 150s2.5 in Britton-Robinson buffer of pH 5. The plot of the resulting ip,, vs. uranium(VI) concentration was linear in the range 2.1 x 10(-9) to 9.60 x 10(-7) mol L-1 uranium(VI) and tended to level off at above 9.6 x 10(-7) mol L-1. The limits of detection and quantification of uranium(VI) were found to be 4.7 x 10(-10) and 1.5 x 10(-9) mol L-1, respectively. A relative standard deviation of 2.39% (n = 5) at 8.5 x 10(-7) mol L-1 uranium(VI) was obtained. The method was validated by comparing the results with that obtained by ICP-MS method with RSD less than 3.3%. The method was applied successfully for the analysis of uranium in certified reference material (IAEA soil-7), and in phosphate fertilizers.