A:
The UV absorption spectrum of the solution employed for measurement of absorbance in the
Assay exhibits maxima and minima at the same wavelengths as that of a similar solution of
USP Flunixin Meglumine RS, concomitantly measured.
B:
Grind a quantity of Granules, equivalent to about 25 mg of flunixin, and transfer the powder to a 50-mL centrifuge tube. Add 20 mL of acetate buffer, prepared by dissolving 4.1 g of anhydrous sodium acetate in 500 mL of water, adding 2.9 mL of glacial acetic acid, and diluting with water to 1000 mL. Rotate the tube for 10 minutes. Extract with 25 mL of ethyl acetate, and use the upper phase as the test solution. Separately apply 10 µL of the test solution and 10 µL of a Standard solution of
USP Flunixin Meglumine RS in methanol containing 1.5 mg per mL to a thin-layer chromatographic plate (see
Chromatography 
621
) coated with a 0.25-mm layer of chromatographic silica gel mixture. Allow the spots to dry, and develop the chromatograms in a solvent system consisting of a mixture of toluene, ethyl acetate, glacial acetic acid, and water (65:30:10:1) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the developing chamber, mark the solvent front, and allow the spots to air-dry. Examine the plate under short-wavelength UV light: the
RF value of the principal spot obtained from the test solution corresponds to that obtained from the
Standard solution.
