Fast analysis of amino acids in wine by capillary electrophoresis with laser-induced fluorescence detection

A fast analytical method has been developed for the determination of nine amino acids, together with serotonin, in wine samples of different origin and vintage. The method is based on capillary electrophoresis coupled to laser-induced fluorescence detection. Separation was obtained by using a fused silica capillary (75 µm id, 74.0 cm total length, 60.0 cm length to detector) and a background electrolyte composed of carbonate buffer (20 mM, pH 9.2), applying a 20 kV voltage. Direct hydrodynamic injection of wine samples was made after an original microwave-assisted derivatisation step with 5-(4,6-dichlorotriazinyl)aminofluorescein. Fluorescence was induced by means of an Ar-Ion laser, exciting at 488 nm. Good linearity (r^2 > 0.9990) was obtained for all considered analytes and sensitivity was also good, with limits of detection in the 7-50 ng/mL range. The method was successfully applied to the analysis of commercial Italian wines and seems thus to be suitable for the determination of the relevant amino acids and serotonin, providing good results in terms of accuracy and precision, together with the advantage of a very fast, microwave assisted derivatisation procedure. Future applications of the method are planned to check for wine adulterations and commercial frauds.