RESUMO
This study describes a simple and sensitive voltammetric method for determining As (III) and As (V)concentrations in ìg.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 ìg.L-1, respectively, for a deposition time of 180 s with the linear range from 1 to 5 ìg.L-1. Standard deviation for 1 to 5 ìg.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 absorptions pectrometry analyses. The grape juice samples analyzed by voltammetric technique showed As (III) and As (V) concentrations ranging 51-71 ìg.L-1 and 34-60 ìg.L-1, respectively. (AU)
O presente estudo descreve um método voltamétrico simples e sensível para a determinação de As (III) e As (V), em μg.L-1. As (III) é determinado pela análise direta, e As (V) é convertido em As (III) por uma solução de redução. A nova concentração de As (III) representa a concentração de As inorgânico total na amostra em análise. As (V) foi determinado pela subtração do As inorgânico total e do As (III). Os limites de quantificação e detecção de As (III) foram, respectivamente, 0,22 e 0,08 μg.L-1 para o tempo de deposição de 180 s; a faixa linear foi de 1 a 5 μg.L-1 e desvio-padrão (n = 10) de 5%, em potencial de -0,68 V. A precisão foi verificada por meio de teste de recuperação em amostras fortificadas [de 98,2% para As (III) e de 96,4% para As (V)]. Estes resultados foram comparados com a análise feita por espectrometria de absorção atômica com geração de hidreto. O método voltamétrico foi aplicado na especiação do arsênio em amostras de sucos de uva contendo concentrações de 51 a 71 μg.L-1 de As (III) e 34 a 60 μg.L-1 de As (V). (AU)