Establishing a Robust High Performance Liquid Chromatography−Ultraviolet Detection Technique for Nitrite Quantification in Pharmaceutical Excipients and Active Pharmaceutical Ingredients

Abstract

Nitrite impurities are frequently present in pharmaceutical excipients as a result of raw material sources and manufacturing processes. These impurities are of regulatory concern because nitrite can react with secondary amines to form nitrosamines, a class of potentially mutagenic compounds, making effective control of nitrite critical to ensuring the safety of pharmaceutical products. Current industrial methods for nitrite detection and quantification, such as ion chromatography and related techniques, are often limited by aqueous solvent compatibility, matrix dependence, or restricted instrument availability, which can hinder routine implementation across diverse pharmaceutical materials. In this study, a fast and sensitive analytical approach was developed to address these limitations by enabling nitrite quantification across excipients spanning a broad range of hydrophilicity to hydrophobicity. The method employs a newly developed nitrite isolation strategy from solid pharmaceutical excipient matrices, followed by rapid derivatization to form a UV-active species that can be selectively quantified using high-performance liquid chromatography with ultraviolet detection (HPLC-UV). The resulting workflow demonstrates robust performance for low-level nitrite detection while maintaining compatibility with standard HPLC instrumentation across the diverse ranges of tested pharmaceutical ingredients. The widespread availability of HPLC systems, combined with the method's rapid response, selectivity, and low detection limits for nitrite, supports its adoption for routine analytical control. This approach, therefore, provides a practical tool for nitrite monitoring and mitigation of nitrosamine formation risk in pharmaceutical formulations.