Furanone hydroxy-2,5-dimethyl, 4-, -, quantification

Sotolon (4,5-dimethyl-3-hydroxy-2(5H)-furanone) and solerone (4-acetyl- y-butirrolactone) were claimed to be responsible for some aroma characteristic of flor sherries wines. These compounds are present only as traces, and are chemically unstable. A system of two gas chromatographs coupled with a four-port switching valve was used to quantitate these components without previous fractionation. The first chromatograph was equipped with an on-column injector, in order to avoid thermal degradation of sotolon in the heated injector, a DB-5 column and an FID. The second chromatograph was equipped with an on-column injector, a DB-1701 column and an FID. The method allowed quantification of solerone and sotolon at concentrations as low as a few ppb (29). 

The majority of the more than 100 odorants (reviewed in [1]) synthesised for use as internal standards are labelled with deuterium. However, during the quantification procedure some deuterated odorants might undergo deuterium-protium exchange, which would falsify the results. Examples are 4-hydroxy-2,5-dimethyl-3(2H)-furanone (furaneol) [68, 69] and 3-hydroxy-4,5-dimethyl-2(5H)-furanone (sotolon) [70], which are consequently labelled with... 

Blank, I., Schieberle, P., and Grosch, W. 1993. Quantification of the flavour compounds 3-hy-droxy-4,5-dimethyl-2(5H)-furanone and 5-ethyl-3-hydroxy-4-methyl-2(5H)-furanone by stable isotope dilution assay. In Progress in Flavour and Precursor Studies (P. Schreier and P. Winterhalter, eds.). Allured Publishing, Wheaton, 111. 

In Figure 7, the labelled internal standards used for the quantification of eight selected key sesame odorants identified on the basis of AEDA results [46, 52] are shown. Most of them were labelled with deuterium since their preparation was relatively inexpensive. In the case of 4-hydroxy-2,5-dimethyl-3(2H)-furanone, the labelling had to be performed via the more expensive carbon-13 labelled intermediates [68], since the deuterated standard underwent significant protium-deuterium exchanges (unpublished data). 

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