A Creative Indirect Spectrophotometric Determination of Naproxen

A New, sensitive spectrophotometric method for determination of Naproxen (Nap) has been proposed. The method is based on a modification of Naproxen into a hydroxy analog (mNap). The modified compound is coupled with the diazotized p-aminobenzoic acid (PABA) in alkaline medium, the resulting orange azo dye exhibit a maximum absorption at 500 nm. Beer's law is obeyed over the concentration range from 10 to 650 g/20 ml, (i.e. 0.5-32.5 g/ ml) with a good sensitivity (molar absorptivity 2.14x104 l.mol-1.cm-1), good precision (RSD% better than 1.93%) and high accuracy (relative error % better than 0.43%), Sandell's sensitivity index is 0.0107g.cm-2 and the limit of detection (LOD) is 0.024 g/ml and the limit of quantitation (LOQ) is 0.082 g/ml. The method has been applied successfully for determination of Naproxen in dosage forms after extraction of the active ingredient. .