A Comprehensive Review of Instrumentation and Applications in Post‐Column and In‐Source Derivatization for LC‐MS

ABSTRACT Liquid chromatography‐mass spectrometry (LC‐MS) has become an indispensable tool for elucidating molecular structures and quantifying diverse compounds within complex mixtures. Despite its versatility, it faces various challenges such as ion suppression, low sensitivity, analyte instability, and matrix effects, which are being overcome by different kinds of offline and online derivatization techniques to improve specificity and reduce potential interferences. In this context, considerable advancements have been made in reviewing and critically evaluating a wide range of developed methods and techniques; however, little attention has been given to post‐column derivatization (PCD) in LC‐MS. Therefore, this comprehensive review highlights state‐of‐the‐art advancements in LC‐MS with a specific focus on various types of chemical and physical PCD, and in‐source derivatization. It also examines the latest instrumentation developments, highlights methods and influencing factors, and explores applications in food, proteomics, biology, pharmaceuticals, and environmental analysis from the past four decades. Besides, this review critically examines the role of PCD in LC‐MS along with outlining its advantages and disadvantages. Furthermore, special emphasis is also made on prospects and insights for developing more versatile LC‐PCD‐MS techniques and in‐source methodologies, to address ongoing challenges and aim to open new research avenues for analysts.