title: Visible spectrophotometric and first-derivative UV spectrophotometric determination of rifampicin and isoniazid in pharmaceutical preparations.
abstract: Two methods are described for the determination of rifampicin and isoniazid in mixtures by visible spectrophotometry and first-derivative ultraviolet spectrophotometry. The absorbance at 475 nm in buffer solution pH 7.4 was employed to determine rifampicin after applying the three-point correction technique between 420 and 520 nm, while the amplitude of the first-derivative spectrophotometric spectrum at 257 nm in HCl 0.012 M was selected for the determination of isoniazid. The methods are rapid, simple and do not require any separation step. The recovery average was 99.03% for rifampicin and 100.01% for isoniazid. The methods were applied to determine the two compounds in commercial capsules and compared with the official method of the USP XXIII with good agreement between the results.
authors.affiliation: Departamento de Farmácia, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, Caixa Postal 66355, CEP 05389-970, São Paulo, Brazil.
authors.forename: S A
authors.initials: SA
authors.lastname: Benetton
authors.forename: E R
authors.initials: ER
authors.lastname: Kedor-Hackmann
authors.forename: M I
authors.initials: MI
authors.lastname: Santoro
authors.forename: V M
authors.initials: VM
authors.lastname: Borges