Fluorometric determination of glycerol in wine--comparison with other known procedures

The glycerol content of 6 wines was evaluated by using 3 different preliminary treatments and, subsequently, a variety of instrumental and chemical procedures (fluorometric, vapor phase chromatography of trimethylsilyl derivatives, volumetric, and colorimetric). The data showed that all these procedures are applicable; in particular, the fluorometric procedure, which has not been used until now, provides average recoveries of added glycerol ranging from 99.3 to 100.9%, with relative standard deviations ranging from 2.9 to 3.2%. Vapor phase chromatography provides average recoveries of added glycerol ranging from 99.8 to 100.1%, with relative standard deviations ranging from 1.0 to 2.7%. Therefore, the fluorometric procedure appears especially useful for reliable routine analyses, because it is specific for glycerol and provides results that are unaffected by preliminary treatment. Thus it allows analysis of diluted wine, when the sugar content does not exceed 5 g/L; sweet wines must undergo an ion exchange pretreatment.