OBJECTIVEA new method for simultaneous determination of four methyl-3, 4-dihydroxybenzoate ( I ), P-coumaric acid (II), ferulaic acid (III) and E-6-O-P-coumaroyl scandoside methyl ester (IV) in Hedyotis diffusa oral solution by reversed-phase HPLC was developed.

METHODThe separation was performed on a Diamonsil C18 column (4.6 mm x 250 mm, 5 microm) with gradient elution. A-acetonitrile, B-methonal-water-glacial acetic acid (5: 95: 0.25), 0-20 min, 1% -16% A; 2042 min, 16% A; 42-46 min, 16%-20%A; 46-65 min, 20% A. The UV detection was set at 265 nm; flow rate 1.0 mL x min(-1).

RESULTThere was good linearity between the peak area and concentration at the ranges of 2.1-105 (r = 0.999 8), 3.5-175 (r = 0.999 8), 1.72-86 (r = 0.999 9), 4.0-200 mg x L(-1) (r = 1.000 0) for I, II, III and IV respectively. The average recoveries of I, II, III and IV were 99.9%, 97.9%, 98.6% and 98.1%.

CONCLUSIONThe method is rapid, simple and accurate, and it can be used for the evaluation of H. diffusa oral solution.