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Updated: Dec 22, 2025

Absolute Quantification of Cell-Free Protein Synthesis Metabolism by Reversed-Phase Liquid Chromatography-Mass Spectrometry
Published on: October 25, 2019
Development of ion pairing LC-MS/MS method for itaconate and cis-aconitate in cell extract and cell media
Bo Tan1, Shruti Malu2, Kenneth D Roth1
1Quantitative Biology, Lilly Research Laboratories, Lilly Corporate Center, Indianapolis, IN 46285, United States.
Abstract:
Accumulation of Immune Responsive Gene 1(IRG1) in macrophage induced by lipopolysaccharide (LPS) and interferon gamma (IFN-γ) leads to production of itaconate by decarboxylation of cis-aconitate. The biology associated with IRG1 and itaconate is not fully understood. A rapid and sensitive method for measurement of itaconate will benefit the study of IRG1 biology. Multiple HPLC and derivatization methods were tested. An ion pairing LC-MS/MS method using tributylamine/formic acid as ion pairing agents and a HypercarbTM guard column we proposed demonstrated better peak shape and better sensitivity for itaconate. The current protocol allows baseline separation of itaconate, citraconate, and cis-aconitate without derivatization and direct analysis of analytes in 80% methanol/water solution to avoid the dry-down step. It provides the limit of quantitation (LOQ) of 30 pg itaconate on column with a 4.5-minute run time. This method is validated for measurement of itaconate and cis-aconitate in RAW264.7 cell extract and cell media in a 96-well plate format. We applied this method to successfully measure the increase of itaconate and the decrease of cis-aconitate in RAW cell extract and cell media after LPS/IFN-γ treatment.
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