FIA—FT—IR determination of ibuprofen in pharmaceuticals

Abstract

A method has been developed for the determination of Ibuprofen (2-[4-isobutylphenyl]-propionic acid) in pharmaceuticals by FT—IR, using the carbonyl band which this compound presents at 1710 cm −1 in carbon tetrachloride solutions. Samples are dissolved in carbon tetrachloride. In this solvent the excipients are not soluble and so the drug can be directly determined without any additional treatment. The use of a simple FIA manifold permits one to carry out this analysis with a low consumption of reagent and the FT—IR provides a continuous monitoring of the spectral base-line which permits an accurate determination of the maximum in the absorbance band. Also, the FIA system permits easy and fast sampling and cleaning of the measurement cell. The method has a dynamic range between 0.5 and 20 mg/ml with a sensitivity of 0.366 ± 0.004 au · mg −1 · ml · mm −1 and a variation coefficient of 0.8% for 5 independent measurements of a real sample containing 200 mg of Ibuprofen per capsule. The developed procedure provides concentration values comparable with those found by UV spectrophotometry in the analysis of real samples but is free from matrix interferences.