Two Novel Spectrophotometric Methods for Determination of Naproxen via a Modulation to Hydroxy Analog

Abstract

Potassium permanganate was used for oxidation of the synthesized hydroxy analog of Naproxen by two methods. In the first method, the oxidation occurred in acidic medium, the excess of permanganate was followed at 545 nm. Beer's law is obeyed between concentrations of 10 µg/10ml-80 µg/10ml (1-8 ppm) with good sensitivity (molar absorptivity of 9.7x10³l.mol^-1.cm^-1), good precision (RSD better than ±3.2 %) and high accuracy (relative error better than 1.6%). Sandell's sensitivity index is 0.0237 µg.cm^-2. The detection limit (LOD) is 0.075 µg‧ml^-1 and the quantitation limit (LOQ) is 0.25 µg‧ml^-1. For the second method, potassium permanganate was used to oxidize the hydroxy analog of Naproxen in basic medium, and the manganate produced was followed at 610 nm. The linearity range was from 20 to 70 µg/10 ml (2-7 ppm) with good sensitivity (molar absorptivity of 6.8 x 10³ l.mol^-1.cm^-1), good precision (RSD better than ±2.5%) and high accuracy (relative error better than 1.51%). Sandell's sensitivity index is 0.0338 µg.cm^-2 while the detection limit (LOD) is 0.0098 µg‧ml^-1 and quantitation limit (LOQ) is 0.03296 µg‧ml^-1. The two methods were applied successfully for the determination of Naproxen after extraction of the active ingredient by ethyl acetate.

Keywords: Naproxen; modulation; oxidation; potassium permanganate

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