Determination of As (III) and As (V) in grape juice samples by differential pulse cathodic stripping voltammetry

Abstract

concentrations in μg.L-1. Electroactive As (III) is evaluated by direct analysis. As (V) is converted into As (III) using reduction solution; the new As (III) concentration, represents the total inorganic As in the analyzed sample. As (III) and total inorganic As determination showed a work potential peak at -0.68 V; As (V) concentration was determined by subtraction [total inorganic As – As (III)]. Quantification and detection limits for As (III) were 0.22 and 0.08 μg.L-1, respectively, for a deposition time of 180 s with the linear range from 1 to 5 μg.L-1. Standard deviation for 1 to 5 μg.L-1 arsenic concentration (n = 10) was 5%. The methodology was successfully applied for identifying and quantifying the inorganic arsenic in grape juices; and the accuracy was assessed by a recovery test on spiked samples, being 98.2% for As (III) and 96.4% for As (V). These results were compared with those from hydride generation atomic absorption spectrometry analyses. The grape juice samples analyzed by voltammetric technique showed As (III) and As (V) concentrations ranging 51-71 μg.L-1 and 34-60 μg.L-1, respectively.