Quantification of Cellular Folate Species by LC-MS after Stabilization by Derivatization

Anal Chem. 2018 Jun 19;90(12):7349-7356. doi: 10.1021/acs.analchem.8b00650. Epub 2018 Jun 5.


Folate cofactors play a key role in one-carbon metabolism. Analysis of individual folate species is hampered by the low chemical stability and high interconvertibility of folates, which can lead to severe experimental bias. Here, we present a complete workflow that employs simultaneous extraction and stabilization of folates by derivatization. We perform reductive methylation employing stable isotope labeled reagents to retain information on the position and redox state of one-carbon units as well as the redox state of the pteridine ring. The derivatives are analyzed by a targeted LC(HILIC)-MS/MS method without the need for deconjugation, thereby also preserving the glutamation state of folates. The presented method does not only improve analyte coverage and sensitivity as compared to other published methods, it also greatly simplifies sample handling and storage. Finally, we report differences in the response of bacterial and mammalian systems to pharmacological inhibition of dihydrofolate reductase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacterial Proteins
  • Carbon
  • Chromatography, Liquid / methods*
  • Folic Acid / analysis*
  • Folic Acid Antagonists
  • Hep G2 Cells
  • Humans
  • Isotope Labeling
  • Mammals
  • Methods
  • Methylation
  • Oxidation-Reduction
  • Pteroylpolyglutamic Acids / analysis
  • Tandem Mass Spectrometry / methods*
  • Tetrahydrofolate Dehydrogenase / drug effects
  • Workflow*


  • Bacterial Proteins
  • Folic Acid Antagonists
  • Pteroylpolyglutamic Acids
  • Carbon
  • Folic Acid
  • Tetrahydrofolate Dehydrogenase