Determination of cadmium and lead in fresh fish samples by direct sampling electrothermal atomic absorption spectrometry

Abstract

The determination of cadmium and lead in fish samples has large analytical interest due to the potential toxicity of these elements. The development of fast and reliable analytical methods is extremely important for an effective control of contamination. In this work, the feasibility of Cd and Pb determination in fresh fish samples using direct sampling by electrothermal atomic absorption spectrometry (DS-ET AAS) was investigated. For optimization of the furnace temperature program, pyrolysis and atomization curves with TORT-2 and DORM-3 certified reference materials were carried out using chemical modifier (0.05% Pd + 0.03% Mg + 0.05% Triton X-100). The figures of merit obtained were: characteristic mass of 1.0 pg and 16 pg and limit of detection (LOD) of 0.2 μg kg−1 and 1.0 μg kg−1 for Cd and Pb, respectively, based on 8 mg of sample mass. The results obtained for certificated references materials were statistically not different from the certified values at 95% confidence level, using the calibration with aqueous standards, showing that this calibration method is suitable for this application. For assessment of the accuracy of the method, fresh fish samples were digested. The results obtained with direct determination of Cd and Pb in fresh fish samples and with microwave assisted acid digestion were statistically accordant. The developed method for analysis of fresh fish samples is accurate, simple, fast and suitable for routine application, avoiding digestion procedures or the drying/lyophilization and grinding procedures, usually used in DS analysis, reducing the preparation time, risk of contamination and costs.