Development and application of the analytical method for illicit drugs and metabolites in fish tissues

In this study, we developed a screening method for highly accurate and sensitive analysis of 12 illicit drugs and metabolites in fish tissues. The approach was based on ultrasonic-assisted extraction and solid phase extraction, followed by ultra-performance liquid chromatography-tandem mass spectrometry analysis. The homogenized samples were ultrasonic-assisted extracted with 1% acetic acid in methanol followed by SPE cleanup with Oasis MCX cartridge. The method was validated in accordance with the European Medicines Agency guidelines by evaluating the following required parameters: the limits of detection and limits of quantification, linearity, accuracy, repeatability, recovery of extraction, and matrix effect. For the tissues involved in this study, the recoveries ranged from 60% to 127%, and the matrix effect ranged from -19% to 83% with the inter- and intra-day variability below 12%. The method has been successfully applied to wild fish caught from six sampling sites of four urban rivers in Beijing, China. The analysis showed that the target compounds, including amphetamine, 3,4-methylenedioxyamphetamine, codeine and heroin were detected with high detection frequencies. Codeine exhibited the highest bioaccumulation factor (up to 73,986) in the muscle of Crucian carp, while ketamine tended to accumulate in the skin, 3,4-methylenedioxyamphetamine and heroin tended to accumulate in gastrointestinal tract, respectively.