Quantitative analysis of related substances in acetaminophen tablets using pre-column derivatization coupled with HPLC–ICP-MS

High-performance liquid chromatography coupled with inductively coupled plasma-mass spectrometry (HPLC–ICP-MS) is a promising structure-independent technique for accurate quantification of drug-related substances in pharmaceuticals. In this study, we aimed to develop a sensitive HPLC–ICP-MS method, combined with pre-column derivatization, to quantify related substances in acetaminophen tablets. Through this method, we enhanced the sensitivity and accuracy of detecting substances that do not directly respond to ICP-MS. The key advancements include the systematic optimization of derivatization conditions and the establishment of a calibration curve with correlation coefficients greater than 0.999. The method achieved impressive limits of quantification: 0.089 µM for o-acetaminophenol, 0.097 µM for p-nitrophenol, and 0.161 µM for p-aminophenol. It demonstrated suitable accuracy and precision for the following substances: o-acetaminophenol with accuracy between 95.7–104.4% and precision ≤ 4.9%, p-nitrophenol with accuracy between 97.6–101.8% and precision ≤ 2.7%, and p-aminophenol with accuracy between 95.6–102.5% and precision ≤ 3.2%. Comparative analysis with standard HPLC–UV method revealed less than 20% difference in quantification, underscoring the effectiveness of this combined technique. Our study demonstrated the feasibility of combining chemical derivatization with HPLC–ICP-MS as a robust tool for the accurate quantification of drug-related substances, particularly those lacking elements detectable by ICP-MS alone.

Graphical abstract