Abstract: A simple and sensitive high performance liquid chromatography (HPLC) method for simultaneous determination of eight monosaccharides in okra polysaccharides by pre-column derivatization with 1-phenyl-3-menthy-5-pyrazolone (PMP) was developed. The monosaccharides were separated on an InfinityLab Poroahell C18 column (4.6 mm × 150 mm, 4 μm), maintained at 25 ℃, using phosphate buffer (0.1 mol/L, pH 6.85): acetonitrile mixture (82:18, V/V) as a mobile phase at a flow rate of 1.0 mL/min. The wavelength of the UV detector was set at 250 nm. Under optimal conditions, the method had wide linear ranges for all monosaccharides, with correlation coefficients above 0.999. The detection limits (LODs) were in the range of 0.13–0.45 mg/kg and the limits of quantitation (LOQs) were in the range of 0.43–1.49 mg/kg. The spiked recoveries ranged from 94.51% to 106.44%, with relative standard deviations (RSDs) less than 5%. The method proved to be simple, rapid and accurate, and could meet the analysis of the monosaccharide composition of okra polysaccharides. This method was successfully applied to analyze the monosaccharide composition of three different polysaccharides from sequential solvent extraction of okra with hot sodium acetate buffer, sodium oxalate-EDTA·2Na-sodium acetate buffer and sodium hydroxide-sodium borohydride solution. The first polysaccharide was composed of mannose, rhamnose, glucuronic acid, galacturonic acid, glucose, galactose and arabinose at a molar ratio of 0.1:7.0:0.4:5.8:0.9:14.6:1.5, the second one was composed of rhamnose, galacturonic acid, galactose and arabinose at a molar ratio of 4.7:61.8:9.6:5.3, and the third one was composed of mannose, rhamnose, galacturonic acid, glucose, galactose and arabinose at a ratio of 9.5:5.4:1.3:10.8:2.4:7.6.

Key words: okra, monosaccharide composition, 1-phenyl-3-menthy-5-pyrazolone pre-column derivatization, high performance liquid chromatography