Simultaneous determination of N-methyl carbamate residues in pork tissues based on ultrasound assisted QuEChERS-dSPE extraction followed by reversed phase LC-FLD analysis

The presence of pesticide residues in animal tissues is a source of public awareness and health concerns. Therefore, to guarantee appropriate food safety and to enforce regulations, efficient, cost-effective and sensitive analytical methods are needed. This study set out to develop and validate a reliable and high-throughput analytical approach for the simultaneous determination of N-methyl carbamates (NMCs) in different parts of pork tissues (kidney, liver and muscle). An innovative sample preparation strategy based on ultrasound assisted QuEChERS extraction (UAE-QuEChERS), instead of manual agitation as original QuEChERS, was evaluated. The NMC insecticides were extracted with acidified (1% acetic acid, v/v) acetonitrile (ACN) and determined by reversed-phase high performance liquid chromatography with fluorescence detection (LC-FLD) after automatic post column derivatization and impurities removal through dispersive solid phase extraction (d-SPE). The separation of NMCs was carried out in a C₈ column using H₂O:ACN (90:10, v/v) and H₂O:ACN (20:80, v/v) as mobile phases. The method showed a good linearity (r² ≥ 0.991), with recoveries generally between 68.6 and 119%. Method limits of detection (LOD) ranging from 0.1 to 2 μg/kg, and method limits of quantification (LOQ) from 0.4 to 6 μg/kg, are satisfactory in terms of the maximum residue limits (MRLs) for NMCs. Suitable intra- and inter-day variations (RSD <12%) and low matrix effects were observed with sample-to-sample variation, for all assayed pork tissues. The utility of the method for implementation in regulatory and food laboratories was demonstrated by its application to the analysis of NMC insecticides in commercial pork tissues. In all cases, NMC residues were not present at concentrations above the LOQ determined for each type of pork tissue.