Determination of five carbohydrate impurities in amino acid bulk drug by HPLC-ELSD

An analytical method was developed for the determination of five carbohydrate impurities in amino acid drug substances by high performance liquid chromatography-evaporative light scattering detection (HPLC-ELSD). Sugar impurities in the amino acid sample were separated and enriched by cation exchange resin. A Lichropher NH₂ column (4.6 mm × 250 mm, 5 μm) was used for chromatographic separation, and a gradient elution was performed using acetonitrile-water as mobile phase. The drift tube temperature was 40 ^oC, the gain value was 8, and nitrogen (350 kPa) was auxiliary gas. Method validation results showed that the limits of detection for fructose, glucose, sucrose, maltose and lactose were in the range of 20.8-75.0 mg/kg and that the limits of quantitation were in the range of 96.2-238.8 mg/kg. Good linear relationship (r ≥ 0.999) were in the linear range for the five sugars, and the recoveries ranged from 84.9%-107.8%. With easy operation, high sensitivity, good precision and reliable accuracy, the method can be used for analysis of residual sugar impurities in amino acid drug bulk drug.