New method for the discovery of adulterated cognacs and brandies based on solid-phase microextraction and gas chromatography - mass spectrometry

Abstract

The article represents new method for discovery of adulterated cognacs and brandies based on solidphase microextraction (SPME) in combination with gas chromatography – mass spectrometry (GC-MS). The work comprised optimization of SPME parameters (extraction temperature and time, concentration of added salt) with subsequent analysis of authentic samples and comparison of the obtained chromatograms using principal component analysis (PCA). According to the obtained results, increase of extraction temperature resulted in an increase of response of the most volatile brandy constituents. To avoid chemical transformations and/or degradation of the samples, the extraction temperature must be limited to 30!C. Increase of the extraction time lead to higher total peak area, but longer extraction times (>10 min for 100 µm polydimethylsiloxane and >2 min for divinylbenzene/Carboxen/polydimethylsiloxane fibers) caused displacement of analytes. Salt addition increased total response of analytes, but caused problems with reproducibility. The developed method was successfully applied for discovery of adulterated samples of brandy, cognac, whisky and whiskey sold in Kazakhstan. The obtained data was analyzed applying principal component analysis (PCA). Five adulterated brandy and whisky samples were discovered and confirmed. The developed method is recommended for application in forensic laboratories.