Optimization of the QuEChERS Method for Determination of Pesticide Residues in Chicken Liver Samples by Gas Chromatography-Mass Spectrometry

The goal of this research was to evaluate the application of Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method for the determination of organochlorine, organophosphate, and carbamate pesticides in fatty animal matrices such as liver of chicken obtained from National Research Institute of Animal Production in Balice (Poland). Pesticides extraction effectiveness was evaluated at two different spiking levels (0.010 and 0.020 mg kg(-1)) and efficiency of the dispersive solid-phase extraction (d-SPE) clean-up step was evaluated by comparison adding different d-SPE sorbent combinations (PSA + GCB, PSA + C-18, PSA + SAX, and PSA + NH2). The analysis of pesticide residues was performed by gas chromatography ion trap mass spectrometry (GC/IT-MS). The linear relation was observed from 0 to 400 ng mL(-1) and the determination coefficient R (2) > 0.997 in all instances for all target analytes. Better recoveries were obtained in samples at 0.020 mg kg(-1) spiking level. The recoveries were in the range 70-120 %, with relative standard deviation (RSD) values lower than 15 % at 0.020 mg kg(-1) spiking level for most pesticides. Similar recovery ratios were obtained with the four different combinations of sorbents tested in the clean-up step, with better precision when the (PSA + SAX) combination was tested. Limits of detection (LODs) ranged from 0.001 to 0.005 mg kg(-1) and limits of quantification (LOQs) ranged from 0.003 to 0.015 mg kg(-1). The proposed method was successfully applied analyzing pesticide residues in real chicken liver samples; detectable pesticide residues were observed, but in all of the cases, the contamination level was lower than the default maximum residue levels (MRLs) set by European Union (EU), Regulation (EC) N 396/2005.