Determination of Residual Organic Solvents in Epalrestat by Headspace GC

OBJECTIVE To establish a method for the determination of residual solvents (methanol, ethanol, dichloromethane, n-hexane, ethyl acetate, tetrahydrofuran, toluene) in epalrestat for controlling the quality of epalrestat. METHODS The solvents were separated on DB-624 capillary column(30 m×0.53 mm, 3.0 μm) with programming temperature, and detected using hydrogen flame ionization detector(FID). The headspace and other chromatographic conditions were as follows:250℃ of detector temperature, 3.0 mL·min^-1 of flow rate, 10:1 of split ratio, 210℃ of inlet temperature, 85℃ of equilibrium temperature and 30 min of equilibrium time. The contents of residual solvents were determined according to the internal standard method(internal standard tert-amyl alcohol). RESULTS There were good linear relationship in the concentration ranges with correlation coefficient above 0.999, respectively. The precisions (RSD values) were less than 5% in all seven kinds of residual solvents, and the average recoveries were within 90.0%-100.0%. CONCLUSION This method had good specificity, high sensitivity, simple operation and accurate results. It was suitable for the determination of above 7 kinds of residual solvents in Epalrestat API at same time.