Method Validation for Determination of Cadmium and Lead in Offal by Means of Quadrupole Inductively Coupled Plasma Mass Spectrometry

Offal includes viscera and internal organs that have been removed from butchered animals, that may be either directly eaten or processed for the production of other foodstuff. Such organs are able to accumulate high concentrations of potentially toxic heavy metals posing a risk for human health when ingested. Because high levels of Cd and Pb may produce damages to humans, Commission Regulation no. 1881/2006 and its amendment established maximum levels for those two elements in edible bovine, porcine, and ovine offal. In the present study, a method based on microwave acid-assisted digestion and quadrupole inductively coupled plasma mass spectrometric quantification of Cd and Pb in offal was validated according to the EU common standards. The main parameters evaluated in the validation process were: the detection and the quantification limits (LoD, LoQ), the recovery, the repeatability, the within-laboratory reproducibility, the linearity range, and the standard measurement uncertainty. The results obtained for LoD and LoQ in mu g kg(-1) were, respectively, Cd, 1.8 and 5.4; Pb, 5.1 and 15.5; meanwhile, the mean recovery was about 98% for Cd and 103% for Pb. Repeatability was around 5% for Cd and 4% for Pb. The expanded standard measurement uncertainty, expressed as percentage and with a coverage factor of 2, was estimated as follows: Cd, 4.9%; Pb, 8.7%. For both elements, the main contribution was due to the within-laboratory reproducibility of the measurements.