SYNTHESIS OF LABELED [H-2(4)]BETA-DAMASCENONE, [H-2(2)]2-METHOXY-3-ISOBUTYLPYRAZINE, [H-2(3)]ALPHA-IONONE, AND [H-2(3)]BETA-IONONE, FOR QUANTIFICATION IN GRAPES, JUICES AND WINES

The syntheses of four isotopically labelled aroma compounds, [H-2(4)]b eta-damascenone, [H-2(2)]2-methoxy-3-isobutylpyrazine, [H-2(3)]beta-io none, and [H-2(3)]beta-ionone, whose natural analogues are commonly fo und in grapes and wines, have each been achieved in a one step reactio n. These compounds were used to establish analytical procedures to qua ntify the natural analogues in grape juices and wines, by gas chromato graphy-mass spectroscopy. The concentration of beta-damascenone, 2-met hoxy-3-isobutylpyrazine, alpha-ionone and beta-ionone in a 1996 St-Emi lion Merlot wine was, 2.9 mu g l(-1), 11.4 ng l(-1), 27.9 ng l(-1) and 84.1 ng l(-1) respectively, with a coefficient of variance below 5% f or each analyte. (C) 1998 Elsevier Science B.V. All rights reserved.