Optimisation of ultrasound-assisted emulsification microextraction method with solidification of floating organic drop for the analysis of cork taint responsible compounds in wine

This paper presents the optimisation of a method based on ultrasound assisted-emulsification method (USAEME) combined with solidification of floating organic drop (SFOD) for the sensitive determination of cork taint responsible compounds in wine. Haloanisoles (2,4,6-trichloranisole (TCA), 2,3,4,6-tetrachloroanisole (TeCA), 2,4,6-tribromoanisole (TBA) and pentachloranisole (PCA)) and their halophenolic precursors were determined by gas chromatography with electron capture detection (GC-ECD). The derivatisation of the halophenols was performed simultaneously with the extraction. To perform the optimisation, the main parameters affecting both extraction and derivatisation were exhaustively studied in different steps. Once the extraction solvent and the pH and time conditions had been determined, experimental design was applied for the simultaneous study of the volumes of acetic anhydride and extraction solvent, temperature and ionic strength conditions. Then, the analytical characteristics of the optimised method were evaluated achieving satisfactory linearity (with correlation coefficients over 0.984), repeatability (below 10.7%) and inter-day precision (below 10.6%) for all target analytes. Moreover, detection limits found were similar or even lower than the olfactory threshold of the studied compounds. Finally, the applicability of the proposed method was tested by analysing real wine samples. To the best of our knowledge, this is the first time that USAEME–SFOD method has been used to determine cork taint responsible compounds in wine.