Application of QuEChERS based method for the determination of pesticides in nutraceutical products (Camellia sinensis) by liquid chromatography coupled to triple quadrupole tandem mass spectrometry.

A QuEChERS (quick, easy, cheap, effective, rugged, and safe) based method has been evaluated and validated for the determination and quantification of approximately 100 LC-amenable pesticides in nutraceutical products obtained from green tea (Camellia sinensis). Extraction was performed with acidified acetonitrile (acetic acid 1% (v/v)), and additional clean-up steps were not necessary. Pesticides determination was achieved using ultra high performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (UHPLC-QqQ-MS/MS). Total running time was 11 min. Pesticides were quantified using matrix-matched calibration. Recoveries ranged from 70% to 117% and relative standard deviation (RSD) was lower than 20% at concentration levels of 25, 50 and 100 µg/kg for intra-day precision and equal or lower than 25% for inter-day precision. Limits of quantification (LOQ) were equal or lower than 25 µg/kg. The validated method was applied to commercial nutraceutical products, detecting acetamiprid (56 µg/kg) and carbendazim (13 µg/kg) in two samples.

Determination of multi-class pesticide residue in dietary supplements from grape seed extracts by ultra-high-performance liquid chromatography coupled to triple quadrupole mass spectrometry.

A new method was developed and validated for the determination of multi-class pesticide residues in nutraceutical products obtained from grape seed extracts. The extraction procedure was based on QuEChERS methodology using ethyl acetate as solvent and a dispersive solid-phase extraction (dSPE) clean-up stage with C18 was included to minimise matrix effects. Pesticides determination was achieved using ultra-high-performance liquid chromatography coupled to triple quadrupole mass spectrometry (UHPLC-QqQ-MS/MS); total running time was 11 min. Pesticides were quantified using matrix-matched calibration. The developed method was validated in terms of matrix effect, linearity, selectivity, limits of detection and quantification, trueness, repeatability and inter-day precision at three concentration levels (10, 50, 100 µg kg(-1)). Suitable recovery values were obtained for 76% of analysed pesticides at the lowest concentration (10 µg kg(-1)). For most of the compounds, relative standard deviation values were lower than 20% and 25% for intra- and inter-day precision, respectively. Finally, 106 pesticides were determined, and the method was applied to seven dietary supplements from grape seed extract, obtaining various positive results for piperonyl butoxide, cyromazine and diniconazole at concentrations ranging from 2.0 to 13.4 µg kg(-1).