Applications of Hydrophilic Interaction Chromatography in Pharmaceutical Impurity Profiling: A Comprehensive Review of Two Decades.

Hydrophilic Interaction Liquid Chromatography (HILIC) has emerged as a powerful and versatile analytical technique for the separation and quantification of polar and ionizable compounds, particularly in the field of pharmaceutical impurity profiling. Over the past two decades, HILIC has gained increasing attention due to its compatibility with mass spectrometry, enhanced retention of hydrophilic impurities, and ability to resolve structurally similar degradation products and process-related impurities that are often inadequately retained by reversed-phase chromatography. This comprehensive review presents a critical overview of HILIC-based methodologies applied to impurity profiling in pharmaceutical analysis from early 2005 to the present. Emphasis is placed on the application of HILIC to both small-molecule drugs and large biomolecules. Additionally, the review categorizes analytical configurations into four main groups based on their operational principles and use cases, offering insights into method selection and performance characteristics. This article serves as a valuable resource for researchers and regulatory scientists seeking to apply HILIC in modern impurity profiling and quality control of pharmaceutical products.