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Updated: Feb 10, 2026

Small-Scale Colorimetric Assays of Intracellular Lactate and Pyruvate in the Nematode Caenorhabditis elegans
Published on: October 15, 2018
Artefactual formation of pyruvate from in-source conversion of lactate
Sophie Trefely1, Clementina Mesaros2, Pening Xu1
1AJ Drexel Autism Institute, Drexel University, 3020 Market St Suite 560, Philadelphia, PA, 19104.
Rationale:
Lactate and pyruvate are high abundance products of glucose metabolism. Analysis of both molecules as part of metabolomics studies in cellular metabolism and physiology have been aided by advances in liquid chromatography-mass spectrometry (LC-MS).
Methods:
We used ion pairing-chromatography and negative ion mode ESI on an QExactive HF to perform stable isotope assisted metabolomics profiling of lactate and pyruvate metabolism.
Results:
Using an LC-MS method for polar metabolite analysis we discovered an artefactual formation of pyruvate from in-source fragmentation of lactate. Surprisingly, this in-source fragmentation has not been previously described, thus we report this identification to warn other investigators. This artefact was detected by baseline chromatographic resolution of lactate and pyruvate by LC with confirmation of this artefact by stable isotope labeling of lactate and pyruvate.
Conclusions:
These findings have immediate implications for metabolomics studies by LC-MS and direct infusion MS, especially in negative ion mode, whereby users should resolve lactate from pyruvate or robustly quantify the potential formation of pyruvate from higher abundance lactate in their assays.
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