A combined high-performance liquid chromatographic-microbiological assay for serum folic acid

Anal Biochem. 1996 Jul 1;238(2):179-83. doi: 10.1006/abio.1996.0272.


An assay of folic acid in human serum is described involving HPLC fractionation of deproteinized serum prior to Lactobacillus casei assay. High specific activity [3H]folic acid is added as internal standard to 1 ml serum prior to deproteinization with perchlorate and an aliquot is applied to a C18 reverse-phase HPLC column. The folic acid fraction was assayed by L. casei microtiter plate assay. Intra- and interassay variations (CV) were 5.5 and 7.5% respectively for sera (n = 10) spiked with folic acid. The percentage recovery for folic acid additions of 10 and 20 ng/liter were 105.2 and 103.7%, respectively. The lower limit of detection was 1 ng folic acid/ml serum. Folates other than folic acid and 5-methyltetrahydrofolate were not detected. The assay permitted serial measurements to be made of folates in serum following an oral dose.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Oral
  • Adolescent
  • Adult
  • Chromatography, High Pressure Liquid / methods*
  • Folic Acid / blood*
  • Folic Acid / pharmacokinetics
  • Humans
  • Lactobacillus casei
  • Male


  • Folic Acid