Quantification by solid phase micro extraction and stable isotope dilution assay of norisoprenoid compounds in red wines obtained from Piedmont rare varieties

A method to identify and quantify megastigmane norisoprenoid compounds in wines was developed using headspace solid phase micro extraction (SPME) coupled with gas-chromatography/mass-spectrometry (GC-MS). Three different compounds were quantified by stable isotope dilution assay (SIDA): beta-damascenone, beta-ionone and alpha-ionone. Particular attention was paid to maximising the method's sensitivity while reducing the extraction time. To optimise the extraction conditions, a statistically designed experiment was performed using extraction time, extraction temperature and ethanol content as operating variables. Five different SPME fibres suitable for the analysis of volatile compounds were compared. This study confirmed that the PDMS/DVB coating performs best for the quantification of beta-damascenone and beta-ionone, and the crucial influence of ethanol content of the sample on extraction effectiveness. Finally, the optimised method was applied to the study of various wines derived from rare and autochthonous grape varieties of north-western Italy. (C) 2012 Elsevier Ltd. All rights reserved.