Multiresidue Analysis of Pesticides in Wine and Grape Using Gas Chromatography with Microelectron Capture and Nitrogen–Phosphorus Detection

Abstract

New multiresidue methods for identification and quantification of over 131 pesticides in wine and grapes have been developed. The analyses were based on gas chromatography with microelectron capture and nitrogen–phosphorus detection (GC-μECD/NPD). Two different extraction protocols (QuEChERS-citrate buffer and unbuffered methods) for wine samples were described. A full validation study of both analytical methods was carried out, including different approaches to cleanup which were evaluated: (a) extracts cleanup via dispersive solid-phase extraction (SPE), (b) the combination of simultaneous extraction with dispersive SPE and (c) extracts without cleanup. Both analytical procedures presented good performance for all analytes, with recoveries in the range of 72–113% and average relative standard deviation (RSD) ≤ 20%. Linearity was studied in the range between 0.009 and 0.023 mg/kg and showed coefficients of determination (R2) ≥ 0.99 for all pesticides. Estimated matrix effects in wine samples which were prepared with the presented methods for most compounds were < 10%. Determination of pesticide residues in grape samples was carried out by the modified QuEChERS approach. Satisfying parameters of recovery and precision at the two spiking levels (LOQ and 100 × LOQ) were achieved almost for all analytes in the range of 70–120% with RSD ≤ 20% (some exceptions were benthiavalicarb isopropyl, carbosulfan, dichlorvos, flazasulfuron, flubendiamide, mevinphos, tetrachlorvinphos and tribenuron methyl). Linearity was observed for all analytes in the concentration range of 0.002–4.158 mg/kg with coefficients of determination ≥ 0.99 except for fenpropidin. The expanded uncertainties were estimated by using a “top-down” approach as being 18% (on average) and 25% (on average) for grape and wine samples, respectively (coverage factor k = 2, confidence level 95%). Finally, the methods were applied with success to determination of pesticide residues in commercial wine and grape fruit samples.