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.