On-line dialysis with HPLC for the automated preparation and analysis of amino acids, sugars and organic acids in grape juice and wines

Abstract
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 sample processor (ASTED) provides an efficient way of preparing and cleaning-up raw liquid food samples. Following the usual preparation steps like dilution, addition of internal standards, mixing and derivatization, 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 sugars, ethanol and glycerol have been determined using two methods. Analytical data are provided both for a grape juice and a red wine.