FLUOROMETRIC HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY FOR QUANTITATION OF NAPROXEN IN SERUM

A simple, sensitive and reliable HPLC method for the determination of naproxen in serum is presented. Samples were prepared by a protein pre cipitation method using acetonitrile. A reversed-phase C-18 column was used with a mobile phase consisting of 47% acetonitrile and 53% pH 2. 5 buffer solution. A fluorescence detection with excitation wavelength of 230 nm and emission wavelength of 370 nm provided high sensitivity and specificity with no interference from normal serum constituents. The limit of quantitation was 2.0 ng/ml with a CV of 10.6%. The standa rd plots were highly linear (r>0.999) over the range of 10.0-200.0 ng/ ml. The average recovery was 97% and the CVs of inter- and intra-day v ariabilities were 2.0% and 1.2%, respectively, for the entire calibrat ion range. The method was used for the measurement of the time course of naproxen in dog serum after administration of a topical gel.