Hassan Abdine

Spectrophotometric determination of acetaminophen, salicylamide and codeine phosphate in tablets

An accurate and simple method is proposed for the analysis of a three-component mixture composed of acetaminophen, salicylamide and codeine phosphate, without the necessity for the previous separation of any component. The first two components are determined directly by independent spectrophotometric measurements, based on the pH-induced spectral changes. Codeine phosphate is assayed by the formation of an ion pair with methyl orange. The procedure has been applied successfully to the analysis of known mixtures and commercial tablets.

Use of charge-transfer complexation in the spectrophotometric assay of antazoline and naphazoline in combination

A simple and accurate spectrophotometric method is described for the assay of antazoline and naphazoline, combined in eye-nose drops in a ratio of 20 : 1. The major component, antazoline, is determined, without interference from naphazoline, by charge-transfer complexation with σ-acceptor iodine. After precipitation of antazoline with sodium carbonate, the minor component, naphazoline, can be determined using the π-acceptor chloranil. The accuracy of the method is assessed by the assay of a standard mixture of the two components containing the same proportions as the commercial preparation.

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.

Use of an orthogonal function in differential spectrophotometry

An orthogonal function method has been applied to the differential spectrophotometric determination of acetazolamide and hydrochlorothiazide in tablets. The error resulting from setting the wavelength scale during the application of the orthogonal function to conventional spectrophotometry is thereby minimised. The results of assay using the proposed method [p2(r) method] are more precise than those obtained with the p2 method.