Simultaneous GLC Estimation of Salicylic Acid and Aspirin in Plasma

Abstract: Plasma salicylates, salicylic acid and acetylsalicylic acid (aspirin), were estimated as their respective trimethylsilyl derivatives by GLC. The method involved the use of fluoride and cooling to minimize the hydrolysis of aspirin in whole blood. Following solvent extraction, internal standards were added to each plasma extract. The extracts were evaporated to dryness and the residues were trimethylsilylated with hexamethyldisilazane in acetone. Small portions of the reaction mixture were chromatographed and the salicylates were quantitated. The components eluting from the chromatograph were identified by IR spectrophotometry and mass spectrometry.