Clean Method for the Simultaneous Determination of Propyphenazone and Caffeine in Pharmaceuticals by Flow Injection Fourier Transform Infrared Spectrometry

Abstract

A procedure is proposed for the simultaneous FTIR determination of propyphenazone (PFZ) and caffeine (CAF) in pharmaceuticals. The method involves the dissolution of the active principles in CHCl ₃ , followed by filtration of sample solutions to remove the excipients. PFZ is then determined by absorbance measurements at 1595 cm ^{- 1} , using a baseline established between 2000 and 890 cm ^{- 1} , and CAF by using the first-derivative values at 1712 cm ^{- 1} , using solutions of PFZ and CAF for external calibration. The method was applied in both the stopped-flow and flow-injection modes, providing precise and accurate results for the analysis of real samples. The incorporation of a distillation unit for the on-line recycling of the CHCl ₃ used as carrier and solvent provides an environmentally friendly analytical methodology which makes possible an injection frequency of 120 samples h ^{- 1} and reduces the cost and side-effects of the production of laboratory waste.