Determination of Aspirin and Salicylic Acid in Aspirin Tablets by Second Derivative Ultraviolet Spectrometry

Abstract

The second derivative ultraviolet (UV) spectra of aspirin and salicylic acid in a solution of powdered aspirin tablets were not interfered with by the intense and time-dependent signal backgrounds caused by excipients and antacids contained in the tablets. The promotion of aspirin hydrolysis to salicylic acid in the solution by antacids could be sufficiently suppressed by using ethanol containing 1% (w/v) of citric acid as a solvent. Three kinds of commercial aspirin tablets were assayed by second derivative UV spectrometry without any procedure for separation of the pharmaceuticals from the tablet additives. The contents of aspirin and salicylic acid could be determined with relative standard deviations of <0.5% for aspirin and <3.0% for salicylic acid. © 1984, The Pharmaceutical Society of Japan. All rights reserved.