Rapid Simultaneous Determination of Salicylic Acid and Aspirin by GC I: Analysis of Synthetic Aspirin—Salicylic Acid Mixtures and of Single-Component Aspirin Tablets

Abstract

A rapid, sensitive GC method for the simultaneous analysis of salicylic acid and aspirin in admixtures and in single-component acetylsalicylic acid (aspirin) tablets is presented. The procedure involves conversion of the two drugs to their methyl esters with diazomethane in tetrahydrofuran solution and subsequent isothermal elution of the components from a 5% OV-210 on Diatoport S glass column. Quantitation is effected by means of an electronic digital integrator with methyl o-methoxybenzoate as the internal standard. The average total drug recovery of 16 synthetic mixtures was 99.70%, with a standard deviation of ±0.58%, while the mean total recovery using the USP procedure was 99.40 ± 0.68%. When applied to the analysis of commercial single-component compressed and enteric coated aspirin tablets, the proposed technique gave results which were, in the majority of cases, in excellent agreement with the USP values for both aspirin and salicylic acid content. With a few formulations, the salicylic acid content was found to be slightly higher with the GC procedure than with the method described in the USP.