Simultaneous Determination of Paracetamol, Orphenadrine Citrate, and Caffeine Ternary Mixture by Different Spectrophotometric Methods

The resolving power of spectrophotometric assisted mathematical techniques was demonstrated for the simultaneous determination of the challenging ternary mixture of paracetamol (PAR), orphenadrine citrate (Or.cit), and caffeine (CAF), where PAR, which has the highest absorptivity, is formulated in a very high concentration compared with Or.cit and CAF. Simultaneous area ratio subtraction (SARS), derivative spectrophotometry (D), constant multiplication (CM), and dual wavelength (DW) resolution techniques were able to resolve the three drugs. In SARS, PAR concentration was determined directly at 304 nm in the division spectra using PAR normalized spectrum as a divisor. After subtraction of the constant and multiplying by PAR normalized spectrum; CAF and Or.cit can be determined by first and fourth derivative methods, respectively, from the division spectra. Also, Or.cit and CAF can be obtained by the DW method and CM method, respectively, upon the division of the obtained ratio spectra by CAF spectrum. The proposed methods were validated with good accuracy and precision over the concentration ranges of 20-90, 3-40, and 1-20 mu g/mL for PAR, Or.cit, and CAF, respectively. Specificity of the proposed methods was assessed by analyzing laboratory prepared mixtures containing different ratios of the cited drugs. The proposed methods were applied successfully for the determination of PAR, Or.cit, and CAF in their dosage form without any interference.