Spectrophotometric and Chromatographic Determination of Acetylsalicylic Acid and Caffeine in Pure and in Tablet Dosage Form

In the present research paper, spectrophotometric and chromatographic assay method has been developed for the simultaneous estimation of acetylsalicylic acid and caffeine in bulk and commercial tablets. Acetylsalicylic acid and caffeine showed absorbance maxima at 228 and 275 nm in 0.1N HCl and at 225 and 272 nm in methanol, respectively. These drugs were estimated in formulations by simultaneous equation method (method A) and absorbance ratio method (method B). Acetylsalicylic acid and caffeine at their respective λmax followed Beer-Lambert’s law at concentration range of 0-28 and 0-1.6 μg/mL. Method B involved measurement of absorbance at isoabsoptive point of these two drugs i.e. at 244 nm in 0.1N HCl and at 240 nm in methanol respectively. HPLC method for simultaneous estimation of these two components employed a SMT-C18, OD-5 100/25 (2504.6 mm) column with a mobile phase of methanol using a UV detector at the wavelength of 240 nm. The method was validated for linearity, accuracy, precision, repeatability and sensitivity. The method was linear for mixture of acetylsalicylic acid and caffeine over a concentration range 20-36 μg/mL (R = 0.9973) and 1.14-2.05 μg/mL (R = 0.9954), respectively. LOD and LOQ of acetylsalicylic acid were 1.70 μg/mL and 5.17 μg/mL and that of caffeine was 0.27 and 0.80 μg/mL, respectively. Both, the spectrophotometric and chromatographic methods were found to be linear, accurate, precise and reproducible with an added advantage of cost effectiveness which can be used for routine quantitative analysis of acetylsalicylic acid and caffeine in pure and tablet dosage form.