Multi-pesticide residue analysis in nutraceuticals from grape seed extracts by gas chromatography coupled to triple quadrupole mass spectrometry

•More than 130 pesticides analyzed simultaneously in nutraceuticals from grape seed.•First study using GC-QqQ-MS/MS in this matrix.•Optimization of different cleanup procedures before GC analysis.•Several pesticides have been detected in analyzed samples.

A reliable method for the determination of more than 130 pesticides at trace levels in dietary supplements from grape seed extracts has been optimized. Extraction process was performed by a modification of QuEChERS (quick, easy, cheap, effective, rugged and safe) methodology using ethyl acetate as extraction solvent and including a cleanup step with C18, graphitized black carbon (GBC), primary secondary amine (PSA) and zirconium oxide (Z Sep+) to reduce the high matrix effect found in these products. A dilution step was also included. Pesticides determination was carried out using gas chromatography coupled to triple quadrupole tandem mass spectrometry (GC-QqQ-MS/MS). Pesticides were quantified using matrix-matched calibration. The developed method was validated in terms of matrix effect, limits of detection (LODs) and quantification (LOQs), linearity, trueness, selectivity, intra-day and inter-day precision at three concentration levels (10, 50, 100 μg/kg). Recovery values between 70 and 120% were obtained for 139 pesticides at 10 μg/kg. Relative standard deviation (RSD) values were lower than 20% and 25% for intra and inter-day precision respectively. Low LODs and LOQs were obtained for the most of compounds (0.5-5.0 μg/kg and 1.0-10.0 μg/kg, respectively). Residues of malathion, chlorothalonil, bifenthrin and terbutryn were found in commercial nutraceuticals from grape seed extract at concentrations ranging from 2.4 to 20.6 μg/kg.