The method LOD was calculated dividing this value by 3.3. The trueness of the method was evaluated by carrying out extraction and analysis of six replicates of blank samples spiked at 20, 40 and 100 μg kg-1, to estimate the accuracy, expressed as recovery (%), and precision, in terms of repeatability (RSDr). Due to the complexity of the studied matrix, the same experiment at three spiked levels was repeated in different days in order to estimate the intermediate precision (RSDip).