Keywords: 
• multi-effect protective cream /
• HPLC /
• diphenhydramine hydrochloride /
• octyl methoxycinnamate /
• octyl salicylate /
• content determination

Abstract: Objective To establish a HPLC method for the simultaneous determination of diphenhydramine hydrochloride,octyl methoxycinnamate and octyl salicylate in multi-effect protective cream. Methods The HPLC condition was as follows.The column was Agilent Extend-C₁₈ (4.6 mm×150 mm,5 μm).The mobile phase was methanol and ammonium acetate buffer solution (20 mmol/L,pH=7.5).Gradient elution.The methanol ratio varies with time as follows:0-10 min,methanol→60%; 10-12 min,methanol 60%→92%;12-20 min,methanol→92%.Acquisition time was 20 minutes.Liquid phase equilibrium time was 10 min.Flow rate was 1 ml/min.UV detection wavelength was 218 nm.Column temperature was 25℃.Injection volume was 15 μl. Results The three components were separated at baseline within 30 min.The methodological verification showed that the standard curves had good linearity (r>0.9995).The inter-day precision were less than 3.0%.The recovery was between 90% and 108%.The RSD% of stability and repeatability were also less than 3.0%.The results showed that the method could meet the requirements of method validation.The contents of the three components in three batches were determined according to the newly established method. Conclusion The method is simple and reliable,can provide a basis for the quality control of multi-effect protective cream,and laid a foundation for its quality standard research.