Improvement of HPLC Determination Method for Related Substances in Glimepiride

OBJECTIVE To improve the method for determining related substances in glimepiride by HPLC. METHODS The determination was performed on an Agilent Zorbax SB-C₁₈ column(250 mm×4.6 mm, 5 μm), and the mobile phase consisted of 500 mL sodium dihydrogen phosphate solution (dissolve 0.5 g of sodium dihydrogen phosphate in 500 mL of water and adjust to pH 2.5 with phosphoric acid) and 50 mL of acetonitrile at the flow rate 1.0 mL·min^-1. The detection wavelenth was 228 nm. RESULTS The solvents had no effects on the impurity determination. An excellent separation was achieved. The LOQs of impurity 1 and 2 were both 10 ng·mL^-1. The linearity were found in the rang of 0.304 2-2.028 μg·mL^-1 and 0.316 2-2.108 μg·mL^-1 for impurity 1 and 2 respectively. The corresponding average recoveries were 100% with RSD 1.4% for impurity 1 and 99% with RSD 1.3% for impurity 2. CONCLUSION The improved method eliminated the solvent disturbance to impurity determination, and is suitable for the determination of impurities in glimepirede.