ONLINE DIALYSIS WITH HPLC FOR THE AUTOMATED PREPARATION AND ANALYSIS OF AMINO-ACIDS, SUGARS AND ORGANIC-ACIDS IN GRAPE JUICE AND WINES

A reproducible and high throughput technique is described for on-line clean-up and routine analysis of small molecules such as amino acids, sugars and organic acids in grape juice and wines. A fully automated s ample processor (ASTED) provides an efficient way of preparing and cle aning-up raw liquid food samples. Following the usual preparation step s like dilution, addition of internal standards, mixing and derivatiza tion, an on-line dialysis procedure is performed before HPLC analysis, to remove macromolecular and microparticulate interferents resulting from complex matrices. Eighteen amino acids, six organic acids, two su gars, ethanol and glycerol have been determined using two methods. Ana lytical data are provided both for a grape juice and a red wine.