High-throughput modified QuEChERS method for the determination of the mycotoxin tenuazonic acid in wine grapes

Abstract

A reliable, simple, fast, inexpensive and robust sample preparation approach for tenuazonic acid (TA) determination in grapes by liquid chromatography with ultraviolet detection (HPLC-UV) is proposed. The method is based on a modified QuEChERS (quick, easy, cheap, effective, rugged and safe) approach using ethyl acetate as extraction solvent. Its involves extraction of 2.5 g sample (plus 2.5 mL 1% formic acid acidified water) with 5 mL of ethyl acetate; drying/cleaning-up of extract with 0.25 g anhydrous CaCl₂ and determination by HPLC-UV. The method was optimized and validated achieving a limit of quantification (LOQ) of 0.05 μg g⁻¹. The overall recoveries were 96%, 82% and 97% for grape samples spiked at 0.05, 0.5 and 5 μg g⁻¹, respectively. The method showed excellent reproducibility with RSDs for the above data ≤8% and Horwitz ratios <0.11. The procedure was applied to evaluate the occurrence of TA in grapes and it was quantified at concentrations ranging between 0.057 and 0.595 μg g⁻¹. The methodological development allows a high throughput routine quality control of grapes, adding a valuable tool for the winemaking industry. The method could be applied in an average laboratory and help to understand possible effects related to Alternaria rotting on the final wines elaborated. As well, this is the first report of TA presence in grapes used for wine elaboration, so the results add new knowledge to a growing research area.