Liquid Chromatographic Assay for Salicylic Acid in Liquid and Semisolid Formulations

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Abstract
A high performance liquid chromatographic assay for quantitating salicylic acid (S) in lotion, collodion, ointment and cream formulations is described. The method involved direct determination of S in the liquid dosage forms after appropriate dilutions with the mobile phase. Prior extraction of S from ointments and creams was carried by chloroform. Metronidazole was used as the internal standard and a U-Bondapak phenyl column with a mobile phase made of 30% methanol in 5 mM solution of tetrabutylammonium phosphate (pH 7.5) led to an efficient separation. Retention times of about 3 and 7.5 min were obtained for the internal standard and S respectively. The recovery of S from the dosage forms was tested by adding known amounts of S to each preparation and mixing before determination. The mean percentage recovery was in the range of 98-101.1%. The method was found to be accurate, simple and reproducible.