Selective extraction and determination of neonicotinoid insecticides in wine by liquid chromatography–tandem mass spectrometry

• Single step concentration and clean-up of neonicotinoids from wine.
• Quantitative extraction yields and negligible matrix effects for red and white wines.
• Accurate recoveries using calibration against standard solutions.
• Imidacloprid residues often detected in commercial wines.

A simplified, high throughput procedure for the determination of five neonicotinoid insecticides in red and white wines, using liquid chromatography (LC)–tandem mass spectrometry (MS/MS), is presented. The effects of different experimental parameters (extraction sorbent, solvent elution and clean-up conditions) in the efficiency and the selectivity of the sample preparation process were assessed through calculation of the extraction yields and the matrix effects (MEs). Wines (10 mL) were concentrated using OASIS HLB cartridges, on-line connected to Florisil clean-up cartridges, with acetonitrile serving as the elution solvent. The extract (5 mL vol) was concentrated to 1 mL and injected in the LC–ESI-MS/MS system. The optimized procedure provided quantitative extraction yields at the same time that the efficiency of ESI ionization remained unchanged between standards and sample extracts. Overall recoveries, calculated against authentic standards in ACN, varied between 77 and 119% and the attained limits of quantification remained below 0.2 ng mL−1. Analysis of commercial wines revealed imidacloprid residues in more than 50% of processed samples, with a maximum level of 14 ng mL−1.