QUANTITATIVE DETERMINATION OF 2-METHOXY-1,4-NAPHTHOQUINONE IN PLASMA BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY

A simple and sensitive high-performance liquid chromatographic method for the determination of spiked 2 methoxy-1,4-naphthoquinone in human plasma has been innovatively developed. A C-18 reversed-phase column was used with a mobile phase consisting of methanol-acetate buffer pH 4.0 (55 : 44 v/v) and UV detection at 275 nm. 2-Methyl-1,4-naphthoquinone was used as an internal standard. By deproteinization of plasma protein with 10% w/v zinc sulfate and methanol, the obtained supernate matrix after centrifugation can be directly injected into the chromatograph. The retention times for the compound and internal standard were 6.78 and 10.18 min, respectively. No interferences from the endogenous substance has been detected. The sensitivity limit of detection was 0.1 mu g/ml of plasma. The accuracy of the method described as the mean of analytical recovery was 101.1% (n 15). The mean percent recoveries (n 18) with respect to the separation efficiency for 2-methoxy-1,4-naphthoquinone and internal standard were 88.42% and 91.07%, respectively. The within-run coefficient of variation (% C.V.) over the concentration range of 0.1 16.0 mu g/ml was 0.9 - 9.9% (n = 3), whereas the between-run coefficient of variation over the same concentration range was 3.8 - 11.0% (n 6). The innovative method described herein is convenient and specific enough for pharmacokinetic and clinical studies.