The determination of sugars in beverages and medicines using on-line dialysis for sample preparation

A method is described for the analysis of sugars in beverages and medicines using on-line dialysis for sample preparation. The design, construction and method development for the on-line dialysis is described. The dialysis is carried out using a novel polypropylene membrane treated for wettability (Celgard 3401) which is mechanically strong and solvent resistant when compared to traditional cellulose acetate membranes. Counter-current dialysis was used at a flow rate of 0.8 ml min−1, with a recipient stream of water and the dialysate was then analysed by high-performance liquid chromatography. Fructose, glucose, lactose, maltose and sucrose were determined in a range of samples. The % RSD of the method was shown to be below 5% and the recoveries above 90% for all samples.