The detection of ?-dicarbonyl compounds in wine by formation of quinoxaline derivatives

A method to determine the most abundant α-dicarbonyl compounds in wine was developed by reaction with 2,3-diaminobenzene. Products such as quinoxaline derivatives were detected by high-performance liquid chromatography (HPLC) or by gas chromatography with a mass-selective detector (GC–MS) or a thermoionic detector (GC–NPD). HPLC and detection with a spectrophotometer (313 nm) were used for routine quantitative analysis of wines. The method is sensitive, linear and has good repeatability. Diacetyl, pentane-2,3-dione, glyoxal and methylglyoxal were quantified in a single run; these compounds are always encountered in wines, but levels vary with different types of wine and also during fermentation and maturation processes. A new dicarbonyl compound, phenylglyoxal, was found in wine. The evolution of dicarbonyl compounds during fermentation is reported in this paper.