It is based on the reaction of Nimesulide with biuret reagent, which forms a greenish coloured complex.
Keywords: Biuret reagent, Cycloogygenase, Nimesulide, Spectrophotometry, Tablet dosage form.
In this developed method, colour was obtained by the reaction of Nimesulide with biuret reagent. The present work therefore demonstrates the spectrophotometric determination of nimesulide in bulk and tablet dosage forms in the visible region.
Our method is based on the reaction of Nimesulide with biuret reagent in the alkaline environment to form a greenish complex with absorption maximum at 400 nm.
Blanking for urine color was performed by subtracting the absorbance of parallel reactions of specimens added to biuret reagent without copper.
Visual examination of the reaction products of biuret reagent with amino acids, peptides, and proteins showed a variation in color.
It was apparent that amino acids and small peptides reacted with biuret reagent very rapidly (Fig.
Biuret reagent was prepared in a two-step procedure by first dissolving 1 g KI, 240 mg CuS[0.sub.4], 3.76 g NaOH, and 24 g NaK tartrate separately in deionized water.
The vials were then centrifuged and 1 mL of solution was added to each cuvette along with 1 mL of biuret reagent. Absorption was read at 550 nm on a UV/Visible spectrophotometer.
A 250/[micro]L portion of each sample was mixed with 1 mL of Biuret reagent
(1.5 g/L cupric sulfate, 6.0 g/L sodium potassium tartrate, and 30.0 g/L sodium hydroxide), mixed by inversion, and allowed to stand for 30 min at room temperature.
After centrifugation (1000g for 10 min), the supernates were discarded, and the pellets of duplicate aliquots were dissolved in either 1 mL of biuret reagent
or reagent without copper sulfate.