OBJECTIVETo establish RP-HPLC method for determination of atropine sulphate, diphenhydramine hydrochloride, capsaicin and dihydrocapsaicin in pain-relieving plaster for arthritis.

METHODThe sample were separated on an Alltima C18 Column (4.6 mm x 250 mm, 5 microm) with the moblie phase of CH3 CN-0.1% H3 PO4. Flow rate was 1 mL x min(-1). The detective wavelength was set at 210 and 280 nm. Column temperature was 30 degrees C.

RESULTThe calibration curve for atropine sulphate, diphenhydramine hydrochloride, capsaicin and dihydrocapsaicin revealed linearity in the range of 2.01-50.25, 15.08-377.00, 5.02-125.50, 5.03-125.75 mg x L(-1), respectively. The recoveries of atropine sulphate, diphenhydramine hydrochloride, capsaicin and dihydrocapsaicin were 99.00% with RSD of 0.95%, 99.89% with RSD of 1.2%, 100.1% with RSD of 1.5% and 99.51%, with RSD of 1.4%, respectively.

CONCLUSIONThe method is simple, rapid and accurate, which is suitable for the quality control of pain-relieving plaster for arthritis.

Arthritis ; drug therapy ; Atropine ; analysis ; therapeutic use ; Capsaicin ; analogs & derivatives ; analysis ; therapeutic use ; Chromatography, High Pressure Liquid ; methods ; Diphenhydramine ; analysis ; therapeutic use ; Drugs, Chinese Herbal ; analysis ; therapeutic use ; Humans ; Pain ; drug therapy