Optimization of Determination of Astragaloside IV in Astragali Radix

Objective: To optimize sample solution preparation method and establish assay method of astragaloside IV in Astragali Radix. Method: UPLC-ELSD was used to determine the content of astragaloside IV with mobile phase of acetonitrile-water( 32 ∶ 68),column temperature of 30 ℃,flow rate of 0. 5 m L·min-1,temperature of ELSD at 45 ℃,carrier gas was dry compressed air with pressure of 0. 5 k Pa, gain value was7. Ammonia-methanol mixture was used to ultrasonic extract of astragaloside IV as well as n-butanol extraction.Preparation method of test solution was optimized through single-factor tests. Result: Optimal preparation method was as following: added methanol 80 m L and concentrated ammonia 40 m L, ultrasonic extraction for 30 min,purification by subsequent extraction with n-butanol for four times every 40 m L in sample preparation. The content of astragaloside Ⅳ from 11 batches of Astragali Radix by this optimizing method were significantly higher than the result determined by HPLC method in 2010 edition of Chinese Pharmacopoeia. Conclusion: This optimized sample preparation method is simple with less loss of effective constituents. UPLC analysis method is accurate and reliable with high sensitivity.