Spectrophotometric determination of paracetamol and caffeine

Abstract

Two UV-visible methods are described, method A to determine paracetamol and caffeine in tablet formulations by spectroscopic derivative. Paracetamol was determined after solving it in sodium hydroxide by taking the first order derivative spectroscopy at 314 nm and caffeine was determined after solving it in bidistilled water by taking the second order derivative spectroscopy at 280 nm. Beers law is obeyed in the concentration ranges 0.78-31.07 μg/mL and 1.51-30.23 μg/mL for caffeine and paracetamol, respectively. Method B to determine paracetamol in tablet and oral formulations. This method is based on the reduction of Fe3+ to Fe2+ by paracetamol, the resulting Fe2+ reacts with 1,10-phenanthroline to give a soluble orange-red complex in acetic acid medium. The maximal absorption is at the wavelength 510 nm. The complete reaction was achieved during heating time 25 min at 45 °C. Beers law is obeyed in the concentration range 1.21-7.56 μg/mL. The limit of detection, limit of quantification and linearity are calculated for both methods.