Different coatings for the HS-SBSE grape volatile analysis in model solution: Preliminary results

Head space stir bar sorptive extraction (HS-SBSE) was used to evaluate the efficacy of two stir bar coatings, poly(ethylene glycol) (PEG)-modified silicone (EG-Silicone) and polyacrylate (PA), in comparison with polydimethyl siloxane (PDMS) coating, to assess volatiles in model wine solutions. In addition, two temperatures (0 °C and 25 °C) of the injection system (CIS) were compared. This was performed to propose an analytical procedure cheaper and faster respect to traditional extractive methods and environmental friendly, avoiding the use of large amounts of solvents and high-energy consumption for cooling. Fifteen grape volatiles with different polarities, known to have an important impact on varietal wine aroma, were tested. The affinity of each tested molecule to the new coatings was assessed. The PDMS coating showed higher relative areas for terpenes (β-citronellol, geraniol, linalool and α-terpineol) and norisoprenoids (β-ionone), especially when the CIS temperature was set at 25 °C. C6 compounds such as 1-hexanol, (E)-2-hexenal, (E)-2-hexen-1-ol, (Z)-3-hexen-1-ol, and benzaldehyde and eugenol, obtained greater area response using EG-Silicone and PA coatings, regardless the temperatures. The memory effect of each coating type was studied; EG Silicone and PA coatings showed a higher memory effect for a certain compounds, probably due to the lower desorption temperature that EG Silicone and PA coatings can be submitted to, respect to PDMS (220 °C the former two, 295 °C the latter).