RESUMO
To achieve high separation power of complex samples using multidimensional gas chromatography (MDGC), the selectivity of the employed stationary phases is crucial. The nonpolar × polar column combination remains the most popular column set used in MDGC. However, resolution of mixtures containing light analytes possessing very similar properties remains a formidable challenge. The development of stationary phases that offer unique separation mechanisms have the potential to significantly improve MDGC separations, particularly in resolving coeluting peaks in complex samples. For the first time, a stationary phase containing silver(I) ions was successfully designed and employed as a second-dimension column using comprehensive two-dimensional gas chromatography (GC × GC) for the separation of mixtures containing alkynes, dienes, terpenes, esters, aldehydes, and ketones. Compared with a widely used nonpolar and polar column set, the silver-based column exhibited superior performance by providing better chromatographic resolution of coeluting compounds. A mixture of unsaturated fatty acids was successfully separated using a GC × GC method in which the elution order in the second dimension was highly dependent on the number of double bonds within the analytes.
RESUMO
In this study, a series of polymeric ionic liquid (PIL) sorbent coatings is evaluated for the extraction of polar volatile organic compounds (VOCs) from Brazilian wines using headspace solid-phase microextraction (HS-SPME), including samples from 'Isabella' and 'BRS Magna' cultivars-the latter was recently introduced by the Brazilian Agricultural Research Corporation - National Grape & Wine Research Center. The structurally tuned SPME coatings were compared to the commercial SPME phases, namely poly(acrylate) (PA) and divinylbenzene/carboxen/poly(dimethylsiloxane) (DVB/CAR/PDMS). The separation, detection and identification of the aroma profiles were obtained using comprehensive two-dimensional gas chromatography mass spectrometry (GC×GC-MS). The best performing PIL-based SPME fiber, namely 1-hexadecyl-3-vinylimidazolium bis[(trifluoromethyl)sulfonyl]imide with 1,12-di(3-vinylimidazolium)dodecane dibis[(trifluoromethyl)sulfonyl]imide incorporated cross-linker supported on an elastic nitinol wire, exhibited superior performance to DVB/CAR/PDMS regarding the average number of extracted peaks and extracted more polar analytes providing additional insight into the aroma profile of 'BRS Magna' wines. Four batches of wine were evaluated, namely 'Isabella' and 'BRS Magna' vintages 2015 and 2016, using highly selective PIL-based SPME coatings and enabled the detection of 350+ peaks. Furthermore, this is the first report evaluating the aroma of 'BRS Magna' wines. A hybrid approach that combined pixel-based Fisher ratio and peak table-based data comparison was used for data handling. This proof-of-concept experiment provided reliable and statistically valid distinction of wines that may guide regulation agencies to create high sample throughput protocols to screen wines exported by Brazilian vintners. Graphical abstract Highly selective extraction of wine aroma using polymeric ionic liquid.