Analysis of terpenes in white wines using SPE–SPME–GC/MS approach

Terpenes contribute to some white wines aroma, especially these produced from Muscat grapes and others aromatic ones of high terpene contents (Gewürtztramminer, Traminer, Huxel, Sylvaner). Terpenes are present in wine in free and bound (in a form of glycosides) forms. Analyses of bound terpenes are usually performed using solid phase extraction after hydrolysis of glycosides. A new method for determination of terpenes from wine, focused on determination of terpenes released after acidic hydrolysis, based on solid phase extraction (SPE) followed by solid phase microextraction (SPME) was developed. Non-polar (free) and polar (bound terpenes) fractions were separated on 500 mg C18 cartridges. Bound terpenes were sampled using SPME immediately after acidic hydrolysis in non-equilibrium conditions. Application of combined SPE–SPME approach allowed quantification of selected terpenes in lower concentrations than in SPE approach and added a selectivity to the method, which enabled detection of compounds non-detectable in SPE extracts. Results obtained by SPE and SPE–SPME approach were correlated for free terpenes and those released after acid hydrolysis 20 white wines obtained from different grape varieties (R2 = 0.923). Although developed for wine terpenes analysis, SPE followed by SPME approach has a great potential in analysis of other bound wine flavor compounds, especially those potent odorants present in trace amounts.