Simultaneous determination of benzoic acid and salicylic acid in Compound Benzoic acid tincture by RP-HPLC

Objective To estabilish a RP-HPLC method for simultaneous determination of benzoic acid and salicylic acid in Compound Benzoic acid tincture.Methods ODSC18 chromatographic column made from Dalian Yilite(4.6mm × 150mm,5μm);mobile phase:methanol: water=60|: 40(pH adjust to 3.2);column temperature:30℃;detection wavelength:242nm;fiow rate:0.9ml/min.Results Ranges of linear of benzoic aci and salicylic acid were 30～120mg/L(R2=0.9995)and 15～60mg/L(R2=0.9988).The average recovery rate was 99.2％(RSD=0.95％)and 99.1％(RSD=1.36％).The RSDs of intra-day were 1.57％ and 1.57％(n=5).The BSDs of interday were 1.43％ and 1.59％(n=5).With t test,difference between Acid-base titration and RP-HPLC was not significant(P＞0.05).Conclusion The metold is simple,accurate and sensitive and can be used for the quality control of Compound Benzoic acid tincture. Key words: Compound Benzoic acid tincture; RP-HPLC; Benzoic acid; Salicylic acid