A Sensitive Derivatization Method for the Determination of the Sugar Composition after Pre-column Reductive Amination with 3-Amino-9-ethylcarbazole （AEC） by High-Performance Liquid Chromatography

3-Amino-9-ethylcarbazole （AEC） was employed for monosaccharide derivatization. The derivatives can be analyzed by high-performance liquid chromatography （HPLC） with an ultraviolet detection （wavelength： 254 nm）. Monosaccharides were quantitatively derivatized with 3-amino-9-ethylcarbazole （AEC） at 70 ℃ for 60 min. The method was linear for all samples over the concentration range tested （r〉0.999）, the precision was found to be satisfactory （R.S.D. 〈 3%）, and the recovery ratios were 〉98.62%. The stability analysis showed R.S.D. was between 1.81%-3.16%. Detection limits for the samples （D-glucose, L-xylose, D-mannose, L-arabinose, and L-rhamnose） ranged from 0.06 to 1.97 ng/mL （S/N=3）. Under the optimized derivatization and HPLC conditions, five monosaccharides were well separated using a narrow bore C18 column （250 mm×4.6 mm） with 0.1 mol/L ammonium acetate containing 25% acetonitrile at a flow rate of 0.5 mL/min. As an application, the method has been successfully applied to the determination of monosaccharide compositions of three polysaccharides SPPA-1, SPPB-1 and SPPC- 1 of Spirulina platensis. This method also has potential application to oligosaccharide or glycan analyses.