On-line solvent recycling: a tool for the development of clean analytical chemistry in flow injection Fourier transform infrared spectrometry. Determination of ketoprofen

A flow injection strategy has been developed for the direct determination of ketoprofen in pharmaceuticals by Fourier transform infrared spectrometry also incorporating a distillation unit which allows the carbon tetrachloride employed to dissolve samples and standards and used as a carrier to be recovered on-line. The system developed permits a drastic reduction of reagent consumption and easy and fast sampling and cleaning of the measurement cell. For the quantification of ketoprofen in pharmaceuticals the carbonyl bands at 1712 and 1666 cm−1 were employed and the developed method provided a 3σ limit of detection of 0.04 mg ml−1, a dynamic range up to 10 mg ml−1 and typical coefficient of variation values between 1.6 and 3%, with a sample injection frequency >42 h−1. Accurate and precise results were obtained in the analysis of real pharmaceutical samples.