Development and validation of a method for Cd, Pb and As analysis in bovine, equine and poultry liver by inductively coupled plasma mass spectrometry

A method for the determination of As, Cd and Pb in bovine, equine and poultry liver by ICP-MS was developed and validated. Samples were digested in a microwave oven using a 10% HNO₃ solution. A set of experiments was made according to a central composite design (CCD) for optimisation of the plasma argon flow, nebuliser argon flow and radiofrequency power applied to the plasma. During the validation, Rh and Ru were evaluated as internal standards and, after validation, the best was Rh for Pb and Cd analysis, but for As better results were obtained without an internal standard. The method allowed As, Cd and Pb determination with a 3.3% HNO₃ solution for the calibration curves ranging from 0 to 40 µg l⁻¹ for As and from 0 to 20 µg l⁻¹ for Cd and Pb. The recovery values obtained showed averages of 100%, 106% and 96% for As, Cd and Pb, respectively. Limits of quantification obtained were 85 µg kg⁻¹ for As, 6.5 µg kg⁻¹ for Cd and 12.5 µg kg⁻¹ for Pb. Repeatability and within-laboratory reproducibility were evaluated through the indicators HORRAT_r and HORRAT_R, and the results were less than 0.30. The method is simple, fast and showed adequate precision and accuracy for the determination of As, Cd and Pb in bovine, equine and poultry liver. The precision, recovery, uncertainties, and limits of detection and quantification for each analyte were in accordance to European Union Commission Regulation 2007/333/EC.