SELECTIVITY CONTROL IN THE ANION-EXCHANGE CHROMATOGRAPHIC DETERMINATION OF SACCHARIDES IN DAIRY-PRODUCTS USING PULSED AMPEROMETRIC DETECTION

The separation of D-glucose, D-galactose, D-fructose, lactose, lactulose, saccharose, maltose, and malto-oligomers on an anion-exchange column in combination with pulsed amperometric detection is described. Resolution was optimized by using separate sodium hydroxide and sodium acetate gradients, generated by a quaternary solvent delivery system. The influence of lithium, potassium, or tetrabutylammonium ions on the separation was found to be negligible. The sample treatment of dairy products consisted of 100-fold dilution with water, followed by ultrafiltration. The recovery of the saccharides in milk was found to be 98.2 to 101.8%, while the repeatability was 0.7% to 5.6%. Determination of saccharides in an infant formula, in a fruit yogurt, and in a candy product are shown. The l.c. anion-exchange chromatographic system described enables the determination of the majority of saccharides present in food products in a single analysis.