Liquid chromatography time-of-flight mass spectrometry following sorptive microextraction for the determination of fungicide residues in wine

This work evaluates the suitability of sorptive microextraction, using disposable silicone sorbents, and liquid chromatography time-of-flight mass spectrometry (LC-TOF-MS) for the determination of 15 fungicides in wine. Under optimized conditions, wine samples (10 mL) were diluted with the same volume of ultrapure water and poured in a glass vessel containing a magnetic stirrer and 4 g of sodium chloride. Extractions were performed at room temperature for 4 h, using an inexpensive silicone disk (12 μL volume) exposed directly to the sample. Thereafter, analytes were recovered with 0.2 mL of acetonitrile. The electrospray ionization (ESI) source was operated in the fast polarity switching mode obtaining, in the same injection, selective LC-MS records (extracted with a mass window of 10 ppm) of compounds rendering [M + H]⁺ and [M-H]⁻ ions. The method provided limits of quantification (LOQs) between 0.1 and 2.2 ng mL⁻¹, linear response ranges up to 500 ng mL⁻¹, relative recoveries from 75% to 117% and an inter-day variability below 15% for all analytes in red and white wine samples. The feasibility of in situ sample enrichment followed by delayed desorption and analysis is also assessed.