Validation of a method for direct cadmium determination in breast milk by graphite furnace atomic absorption spectrometry using tantalum treated graphite tube and co-injection of iridium as chemical modifier

Paulo Celso Pereira Lara, Josi

Abstract

A method for direct cadmium determination in breast milk by graphite furnace atomic absorption spectrometry (GF AAS) was developed in this work. Twenty six experiments were conducted for optimization of the pyrolysis temperature and time, type of modifier and sample treatment. The optimum results were 550ºC and 30 seconds for pyrolysis temperature and time, respectively, permanent Ta + co-injection of Ir solution as modifiers and samples prepared at room temperature with nitric acid. This method allowed cadmium determination under the optimized conditions with a calibration curve ranging from 0 to 3.0 μg L-1. Limit of detection, quantification and characteristic mass obtained were 0.11 mg L-1, 0.36 μg L-1 and 0.37 pg, respectively. Recovery studies at three concentration levels presented results ranging from 96 to 99%. Intra and inter-assay studies revealed coefficients of variation ranging from 1.7 to 11.4%, respectively. The method was applied to determine cadmium in six samples and concentrations ranged from 0.23 to 1.56 μg L-1.