DIRECT ANALYSIS OF MANNITOL, LACTULOSE AND GLUCOSE IN URINE SAMPLES BY HIGH-PERFORMANCE ANION-EXCHANGE CHROMATOGRAPHY WITH PULSE AMPEROMETRIC DETECTION - CLINICAL-EVALUATION OF INTESTINAL PERMEABILITY IN HUMAN-IMMUNODEFICIENCY-VIRUS INFECTION

Clinically, the ratio of lactulose/mannitol excretion in urine after a dministration of these non-metabolized sugars has been used to evaluat e the extent of malabsorption and intestinal permeability disruption i n several infections and nutritional diseases, including human immunod eficiency virus (HIV) infection. A range of methodologies have been re ported to determine the lactulose/mannitol ratio, including enzymatic assay, gas-liquid chromatography (GC), thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). Most published met hods involve tedious sample preparations, rendering them unsuitable fo r routine or automated clinical laboratory testing. We describe in thi s paper a method in which weak anion-exchange high-performance liquid chromatography in conjunction with a pulsed amperometric detector was used. It requires very simple sample preparation and avoids interferen ce by other components present in the urine. The linear range of deter mination for mannitol, lactulose and glucose are up to 10 nmol, in a s ingle injection. The limits of detection are 8, 12, 47 and 52 pmol, re spectively, for mannitol, glucose, lactose and lactulose. The separati on and quantification using this method are highly reproducible, yield ing standard errors of less than 2.5% for retention times and less tha n 3.5% for quantitation. The ratios of lactulose/mannitol recovery in controls and in HIV-infected subjects with and without diarrhea showed striking differences, which are in close agreement with the published results derived with similar HPLC methods.