Direct Determination of Volatile Congeners in Wine Using SPME–GC–MS with Minor Sample Preparation

In this study, the “Ethanol as an Internal Standard” method was employed for the quantification of volatile congeners in wines using headspace solid phase microextraction (SPME) as a way of sampling and gas chromatography coupled to mass spectrometry detector (GC–MS) for detection. The “Ethanol as an Internal Standard” method is fast, cheap, and simple, and demonstrates good compatibility with green analytical chemistry standards. SPME sampling was performed without sample pre-treatment beyond dilution with water. A series of standard solutions containing 10 commonly encountered wine congeners was prepared gravimetrically to test the method’s linearity and sensitivity. The proposed method was then compared to the traditional internal standard (IS) method, using 1-pentanol as the IS compound. Although the precision and linearity for some compounds were slightly lower when using the proposed method, these issues can be mitigated through further optimisation of the SPME methodology. In terms of accuracy, the proposed method exhibited similar recoveries to the traditional IS method: 98.5 ± 8.8% and 103.4 ± 9.8%, consequently. Ten real wine samples (four white and six red) produced in Austria were simultaneously analysed using both IS methods for comparison. The results of the paired t-test showed that the mean concentrations of individual congeners obtained from both IS methods did not differ significantly (p = 0.05), with only one congener exhibiting a statistically significant difference. Given its outstanding practical advantages, the “Ethanol as an Internal Standard” method is recommended for wine analysis.