Impurity Profiling in Pharmaceuticals: Strategies and Tools for the Detection, Quantification, and Control of Impurities in Drug Substances and Products

Impurity profiling is a critical aspect of pharmaceutical quality control, encompassing the identification, characterization, quantification, and regulation of impurities in both drug substances and drug products. Impurities may originate from synthetic processes, degradation pathways, residual solvents, or interactions with packaging materials, and their presence can significantly impact drug safety, efficacy, and regulatory compliance. A wide range of advanced analytical techniques, including chromatographic methods (HPLC, GC, UPLC), spectroscopic tools (NMR, IR), and mass spectrometric approaches (LC-MS/MS, GC-MS), are employed for impurity profiling. International regulatory frameworks, particularly ICH guidelines Q3A–Q3D and M7, provide clear specifications for impurity limits and control strategies. This report outlines the various sources and classifications of impurities—organic, inorganic, residual solvents, and genotoxic—and emphasizes the role of Quality by Design (QbD), method validation, and risk assessment in establishing robust impurity control.