Desenvolvimento de Método Analítico para Determinação de Cd e Pb em Amostras de Goma Xantana por GF AAS.

Abstract

This work presents the development of a method for the determination of Cd and Pb in xanthan gum samples by graphite furnace atomic absorption spectrometry, using NH4H2PO4 as a chemical modifier. The preparation of the samples was made from acid decomposition using a reflux system adapted to the digesting tubes. With this system it was possible to raise the temperature of the digester block to 220 ºC, without loss of acid and/or analyts by volatilization. The samples were mineralized in 5mL of HNO3 for a period of 3 h. The detection limits for Cd and Pb were 2.2 and 33.8 ng g-1, respectively. The RSDs for both analytes were, on average, less than 5.0%. To evaluate the accuracy of the proposed method, analyse addition and recovery tests were performed, obtaining results in the range of 84 to 103% of recovery. The methodology developed was used for the analysis of three commercial samples of xanthan gum, which presented Pb concentrations below the detection limit of the method. For Cd, only one sample presented a concentration value above the quantification limit. However, the Cd content in this sample was below the limit established by the current legislation for xanthan as a food additive.