Simultaneous determination of rifampicin and isoniazid in urine and pharmaceutical formulations by multivariate visible spectrophotometry

摘要

Partial least squares regression (PLSR) was used for the simultaneous quantification of rifampicin (RIF) and isoniazid (INH) by visible spectrophotometry using a simple derivatization reaction. In the presence of neocuproine, copper(II) is easily reduced by INH to a Cu(I)-neocuproine complex that shows an absorption maximum at 455 nm. Under these conditions, RIF shows an absorption maximum at 449 nm. The calibration set was established between 8 and 57 mg L~(-1) for RIF and 1.5 and 7 mg L~(-1) for INH. The method was applied to the determination of the drugs in urine samples (recoveries between 92 and 119%) and in pharmaceutical formulations (relative error lower than 5%).