Catalytic adsorptive stripping voltammetric determination of Cr(VI) in EDTA extracts from solid samples

A catalytic adsorptive stripping voltammetric procedure which allows for Cr(VI) determination in EDTA extracts is presented. EDTA used for extraction can be exploited as a masking agent for Cr(III). The calibration graph for Cr(VI) for an accumulation time of 60 s was linear in the range from 2 × 10−10 to 3 × 10−8 mol L−1. The relative standard deviation for a Cr(VI) concentration of 2 × 10−9 mol L−1 was 5.1% (n = 5). The detection limit estimated from three times the standard deviation of low Cr(VI) concentration and accumulation time of 60 s was about 7 × 10−11 mol L−1. The influence of foreign ions commonly present in extracts from solid samples is presented. The proposed voltammetric procedure was applied to determine Cr(VI) in EDTA extractable chromium from soil certified reference materials CRM 483 and CRM 041. The performance of the method was also verified by studying the recovery of Cr(VI) from spiked river water.