Recent advances in the bioanalysis of acylcarnitines: Methodologies, challenges, and clinical perspectives

Acylcarnitines (ACs) are a diverse class of fatty acid esters of L-carnitine that serve as critical mediators in energy homeostasis and mitochondrial function. Beyond their classical role in newborn screening for inborn errors of metabolism, ACs have emerged as promising biomarkers for complex pathologies, including cardiovascular diseases, diabetes, and drug-induced toxicities. However, the accurate quantification and comprehensive profiling of ACs in biological matrices remain analytically challenging due to their broad polarity range, vast concentration disparities, and the presence of isomers. This review provides a comprehensive overview of the current bioanalytical strategies for ACs, covering sample preparation techniques and detection platforms, with a focus on liquid chromatography-mass spectrometry. Special attention is given to the differentiation of isomers. Finally, we discuss the clinical applications of ACs profiling and highlight future perspectives, including the integration of ion mobility spectrometry, automated high-throughput workflows, spatial and single-cell metabolomics, and AI-driven analytics, to pave the way for precision medicine.