Quantitative measurement of metabolites is essential to understand biological and disease processes. Absolute quantification is a key method to determine the concentration of metabolites in biological samples. However, MS-based absolute quantification is often challenged by the commercial availability and high costs of isotope-labeled internal standards. Absolute quantification of metabolites with excellent accuracy and precision can be achieved with five-plex iDiLeu labeling without the need of isotope-labeled internal standards.
