Analysing multi-class pesticide residues in tilapia fish: development and validation of LC-MS/MS and GC-MS/MS methods

Pesticides are an integral part of increasing food production and have remarkable agricultural benefits such as an increase in crop yield. However, they have been identified as some of the most hazardous substances in food, particularly in fish, posing a risk to both ecosystems and human health. Therefore, this study focuses on the development and optimisation of an analytical technique to detect multiple pesticide residues in fish products. The method involves liquid-liquid extraction, followed by analysis using both liquid and gas chromatography coupled with mass spectrometry. A total of 411 pesticides were selected (e.g.: insecticides, fungicides, and herbicides) and the concentrations of their residues in tilapia (Oreochromis niloticus) were determined. The samples were processed according to the optimised QuEChERS (quick, easy, cheap, effective, rugged, and safe) method, including extraction and clean-up procedures. Lipid co-extracts were successfully minimised before instrumental analysis using optimised cleanup. Matrix-matched calibrations were performed at two different levels (0.05,0.01 mg/kg) in tilapia fish to compensate for signal enhancement/suppression. The validation procedure was performed to assess accuracy, precision, limit of quantification (LOQ), and uncertainty according to the SANTE guidelines. The LOQs of this method were 0.01 mg/kg for all selected pesticides except Cyazofamid, Dodine, Fenpyrazamine, Methomyl, Oxadiargyl, Parathion ethyl, Parathion methyl, Prothioconazole Desthio, and Tolylfluanid were 0.05 mg/kg. The suggested method was implemented to investigate the levels of pesticide residues in fresh fish samples (n = 15) procured from local markets in Egypt. Only two samples had residues of the targeted analytes. In light of our findings, the devised methodology was effectively utilised for the detecting and measurement of pesticide residues present in fish samples.