New and efficient microextraction solid-phase extraction method for the gas chromatographic analysis of wine volatiles

A new method for analysing wine volatiles has been developed. The main features of the proposed method are (1) the minimal use of solvents to reduce overall analysis time and (2) the use of a silica solid-phase extraction cartridge to selectively separate the wine volatiles into two fractions prior to quantitative measurement by gas chromatography. In this method a wine sample is first adjusted to 13% alcohol (v/v). An alcoholic fraction containing the majority of the volatile compounds is then obtained by salting-out the wine. Wine volatiles present in this fraction are micro-extracted by a liquid-liquid partition with 1,1,2-trichlorotrifluoroethane (freon 113). This freon extract is then applied onto a silica solid-phase extraction cartridge to selectively obtain two fractions that are directly injected into the gas chromatograph. Repeatability of the method is better than 5% (as R.S.D.) for more than 50 wine volatiles. Linearity was studied for all 50 compounds, and was satisfactory in most cases. Recovery of volatiles was checked by the analysis of spiked samples, and was also satisfactory. Detection limits with flame ionisation detection (FID) are below 1 mu g/l for the best extracted compounds.