Enrichment sampling methods for wine discrimination with gas sensors

A comparison between two sampling methods based on sample concentration (purge and trap (PT) and solid-phase micro-extraction (SPME)) applied to gas sensors (electronic nose) for wine discrimination is performed. Two different traps have been used in the Tekmar 3100 purge and trap concentrator: trap containing Tenax and Tenax/silica gel/charcoal. Four different types of fiber coating have been used for SPME method: 100 μm polydimethylsiloxane (PDMS), 65 μm polydimethylsiloxane/divinylbenzene (PDMS/DVB), 85 μm polyacrilate and 75 μm carboxen/polydimetilsiloxane (CAR/PDMS). The cell containing a tin dioxide multisensor was mounted inside the gas chromatograph (GC) oven, connected to the injector by replacing the chromatographic column. In this way, the GC injection port has been used to connect the purge and trap and fiber holder to sensors cell. Samples of five different wines elaborated with the major varieties of DO Vinos de Madrid were used for testing the discrimination capability of the systems. Multivariate analyses as principal component analysis (PCA) and artificial neural netwoks (ANN) have been applied to the data to discriminate among the different wine samples. Results show that purge and trap technique provide better response. Tenax trap and 85 μm polyacrilate fiber obtained the highest success rate in classification.