Method Development and Validation of Dual Wavelength UV Spectrophotometric Method for Simultaneous Estimation of Paracetamol and Caffeine in Combined Dosage Form by Internal Standard Method

Abstract

A simple, accurate and precise dual wavelength spectrophotometric method has been developed for simultaneous determination of paracetamol and caffeine in combined pharmaceutical dosage form. The absorbance difference between two points on the mixture spectra is directly proportional to the concentration of the component of interest. During selection of two wavelengths, the interfering component shows same absorbance while the component of interest shows significant difference in absorbance with concentration. The literature review reveals that there is no dual wavelength method was developed for this combination of drugs, hence this method was developed. The wavelengths selected for determination of paracetamol were 260 nm and 281 nm, whereas, the wavelengths selected for determination of caffeine were 234 nm and 249 nm. The concentration of caffeine is very less in formulation, hence standard caffeine API is added to make it detectable in terms of absorbance. Methanol was taken as a solvent. Regression analysis of Beer’s plots showed good correlation in concentration range of 10-60 μg/mL for paracetamol and 3-18 μg/mL for caffeine. Accuracy of method was found between 98-102 %. The precision (intra-day, inter-day and analyst to analyst) of method was found within limits (% CV < 2). The proposed method was successfully applied to determination of these drugs in commercial tablets.