Object To establish a new method to determine protocatechualdehyde in Maodongqing Sustained- release Tablet. Methods The RP- HPLC method was applied with CH3OH and 1 % acetic acid as mobile phase, flowrate at 1.0 mL/min, and detection wavelength at 312 nm. Results In the range from 11.7 ng to 140.4 ng, protocatechualdehyde was in a good line with peak area, r=0.99995, the average recovery ratio was 96.41 % , RSD=1.04 % (n=5). Conclusions It was the first time to establish the RP- HPLC method to determine and control the protocatechualdehyde in Maodongqing Sustained- release Tablet with accuracy and a good reproducibility.

Objective To study the fingerprint determination method of Pogostemon cablin by HPLC.Methods A RP-HPLC method was established with the mixed solution of methnol and 0.1 % acetic acid aqueous solution as mobile phase(gradient elution),flow rate at 1.0 mL/min,detection wavelength at 254 nm,analytic time being 50 min and column temperature at 25 ℃.Results The results of comparative analysis of 10 batches samples showed that 15 common peaks were shared by Pogostemon cablin.The common peaks were classified to two regions and the second was the main characteristic region which had an amount of characteristic peaks.All samples had the similar fingerprint features.Conclusion The method is accurate,repetitive and can be applied for the identification and quality control of Pogostemon cablin.