(T1130-09-61) Reliable HPLC Method for the Simultaneous Determination of Aspirin and Associated Related Substances in Drug Substance and Tablet Formulation

Purpose: To ensure compliance with the current good manufacturing practices (CGMP) regulations, the manufacturers must assure the identity, strength, quality, and purity of the pharmaceutical drug products. This requires establishment of robust analytical test methods that produce reliable and accurate results over the routine use in quality control (QC) laboratory. Aspirin is a common drug for relieving minor aches, pains, fevers, as well as prevention of heart attacks and mini strokes. Aspirin is available in tablets for oral administration, with 81–650 mg of aspirin per tablet. In this work, a single HPLC method was developed for the analysis of aspirin active pharmaceutical ingredient (API) and six related substances. Method performance characteristics including system suitability, linearity, accuracy, intraday and interday precisions were assessed in this study.

Methods: Crushed tablets were dissolved in diluent (60:40 water/acetonitrile with 0.1% formic acid) by sonication for 10 minutes, centrifuged for 10 minutes at 3000 rpm and diluted to 0.1 mg/mL. The chromatographic separation was carried out using a XSelect™ HSS T3 (4.6 x 150 mm, 3.5 µm) column at 40ºC with a flow rate of 1.8 mL/min on the Alliance™ iS HPLC System. A mobile phase consisting of 0.1% formic acid in water and 0.1% formic acid in acetonitrile solvent was delivered using a gradient elution over 7.6 minutes. The injection volume was set to 15.0 µL and UV detection at 237 nm.

Results: The analysis of aspirin API and associated related substances was performed under MS compatible conditions. The XSelect HSS column successfully separated all analytes, producing a USP Resolution (USP Rs) ≥ 4.9, peak tailing of 1.1 – 1.2, and retentivity factor (k*) ≥ 2.1 (Figure 1). The performance of the method was assessed by measuring system suitability of five replicate injections of the standard mixture for intraday and interday assay analysis. The intraday and interday performance demonstrated excellent repeatability of replicate injections with relative standard deviation (RSD) of the peak areas and retention times ranging from 0.03 to 0.30% and 0.01 to 0.03%, respectively. The method was found to be linear in the range of 80 to 120% with respect to the aspirin API working concentration of 0.1 mg/mL, producing a correlation coefficient (R²) ≥ 0.998. The assay results for aspirin and impurities content in the tablet formulation met the criteria specified in the USP monograph for Aspirin Tablets (USP43-NF38).

Conclusion: The HPLC method for the analysis of aspirin API and associated related substances was found to be repeatable, reproducible, linear, and accurate. Method demonstrated reliable analysis of aspirin and related substances in drug substance and tablet formulation.

References: USP monograph for Aspirin Tablets. United States Pharmacopeia USP 43-NF 38, official 1May2020

Figure 1. Chromatographic separation