Spectrophotometric Determination of Mefenamic Acid Using The Oxidation Reduction Reaction of Iodide and Iodate Ions

Abstract

A sensitive indirect spectrophotometric method is proposed for determining
mefenamic acid in pure form and in its pharmaceutical preparations. The method is
based on the reaction of mefenamic acid with potassium iodate and potassium iodide
to liberate iodine , which is immediately converted to triiodid ion complex in presence
of an excess of potassium iodide solution to form yellow dye ,which exhibits
maximum absorption at 347 nm. Beer’s law is obeyed over the range 10 to 1200 μg of
mefenamic acid in final volume 25 ml, i.e.,0.4- 48 ppm with a molar absorptivity of
0.904×104l. mol-1.cm-1 and Sandell’s sensitivity index of 0.0266 μg.cm-2, a relative
error of -0.625 to 1.470 % and a relative standard deviation of ±0.336 to ±1.764 %
depending on the concentration level . The proposed method has been applied
successfully to determine mefenamic acid in pharmaceutical preparations.