Spectrophotometric determination of methylphenobarbitone by use of orthogonal polynomials.

A direct spectrophotometric method for the determination of methylphenobarbitone in presence of degradation products is presented. The method is based on use of the combined polynomial method. The coefficient of the combined polynomial P(w), calculated over the wavelength range 228-272 nm at 4-nm intervals, is unaffected by the presence of any degradation products and is linearly related to the methylphenobarbitone concentration with a relative standard deviation of 0.4%. The mean recovery is 99.1 +/- 0.8%. The method can also be used for assessing the stability of methylphenobarbitone.