Simultaneous spectrophotometric estimation of valdecoxib and tizanidine HCl in mixture
Department of pharmaceutical Analysis, Adhiparasakthi College of Pharmacy, Melmaruvathur-603 319, India
ASK Sankar Department of pharmaceutical Analysis, Adhiparasakthi College of Pharmacy, Melmaruvathur-603 319 India E-mail: [email protected]
Two simple, rapid, accurate and economical methods have been developed for the estimation of valdecoxib and tizanidine HCl in the mixture. Valdecoxib has an absorbance maximum at 243 nm and tizanidine HCl has two absorbance maxima at 228 nm and 320 nm in methanol:0.1 M HCl (1:1) mixture. The linearity was observed in the concentration range 5-30 µg/ml for valdecoxib and 2-20 µg/ml for tizanidine. First method is based on the simultaneous equations and second method is based on Q absorbance ratio. Absorbances at 243 nm and 228 nm were selected for simultaneous equations method. Absorbance at isoabsorptive point 280.4 nm and at 243 nm, the λmax of valdecoxib were selected for absorbance ratio method. These methods were validated statistically. The recovery studies confirmed the accuracy of the proposed methods.