[Determination of resorcinol and salicylic acid in piyanning tincture by high performance liquid chromatography].

A method for the simultaneous determination of resorcinol and salicylic acid in Piyanning tincture by HPLC has been proposed. Operating conditions were Hyppersil ODS column, 4.6 mm x 200 mm, V (methanol): V(water): V(acetic acid) = 50:50:0.9 mobile phase and UV detection at 285 nm. The linear ranges of the method were 0.05-0.25 g/L(r = 1.000) for resorcinol and 0.025-0.127 g/L(r = 1.000) for salicylic acid. The limits of detection were both 0.2 mg/L at a signal-to-noise of 3. The assay method was capable to resolve resorcinol and salicylic acid from their impurities.