Simultaneous spectrophotometric determination of acetylsalicylic acid, paracetamol and caffeine in pharmaceutical preparations

Differences in the UV spectra of acetylsalicylic acid (A SA), paracetamol ( P) and caffeine (C) in ethanol have made rile grounds for a new spectrophot ometric method for the determination of particular components in "Thomapyri n" preparation, without the separation of active substances. The analytical wavelengths were 226 Inn for acetylsalicylic acid, 250 nm for paracetamol and 272 nm for caffeine. For all compounds analysed, the specific absorptio n in ethanol at these three wavelengths was determined. The appropriate equ ations were derived and the method was validated taking into account its sp ecificity, limits of quantitation of ASA, P and C, linearity in the range f rom about 50% to 120% relative to the values declared in "Thomapyrin", accu racy and precision.