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J Clin Pathol. 1992 April; 45(4): 344–347.
PMCID: PMC495277

Microbiological assay on microtitre plates of folate in serum and red cells.


AIMS: To develop a simple microbiological assay for serum and red cell folates on 96-well microtitre plates, suitable for use in routine clinical diagnosis. METHODS: Use of a chloramphenicol resistant organism (NCIB 10463) saved time by avoiding aseptic precautions. Use of plate sealers facilitated mixing. Evaluation of assay performance included estimations of folate recovery, assay reproducibility, and response to reduced folate. Results obtained on sera (193) and red cell folates (150) were compared with those obtained using a traditional microbiological assay. RESULTS: Good recovery of folic acid added to serum and also good interassay and intra-assay precision were obtained with both serum (CV% of less than 5) and red cell folate pools (CV% of less than 5). Equimolar assay responses were obtained with folic acid, 5-formyltetrahydrofolate (L-form), and 5-methyltetrahydrofolate (L-form). The microassay correlated well with a traditional assay for estimation of folate in both serum (n = 193, r = 0.975) and red cells (n = 150, r = 0.96). CONCLUSIONS: This assay is more compact and less time consuming than the traditional assay. It is extremely economical and is easy to perform in a routine clinical laboratory.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Newman EM, Tsai JF. Microbiological analysis of 5-formyltetrahydrofolic acid and other folates using an automatic 96-well plate reader. Anal Biochem. 1986 May 1;154(2):509–515. [PubMed]
  • Horne DW, Patterson D. Lactobacillus casei microbiological assay of folic acid derivatives in 96-well microtiter plates. Clin Chem. 1988 Nov;34(11):2357–2359. [PubMed]
  • Hoffbrand AV, Newcombe FA, Mollin DL. Method of assay of red cell folate activity and the value of the assay as a test for folate deficiency. J Clin Pathol. 1966 Jan;19(1):17–28. [PMC free article] [PubMed]
  • Grossowicz N, Waxman S, Schreiber C. Cryoprotected Lactobacillus casei: an approach to standardization of microbiological assay of folic acid in serum. Clin Chem. 1981 May;27(5):745–747. [PubMed]
  • Wilson SD, Horne DW. Use of glycerol-cryoprotected Lactobacillus casei for microbiological assay of folic acid. Clin Chem. 1982 May;28(5):1198–1200. [PubMed]
  • O'Broin JD, Scott JM, Temperley IJ. A comparison of serum folate estimations using two different methods. J Clin Pathol. 1973 Jan;26(1):80–81. [PMC free article] [PubMed]
  • Kelleher BP, Scott JM, O'Broin SD. Use of beta-lactamase to hydrolyse interfering antibiotics in vitamin B12 microbiological assay using Lactobacillus leichmannii. Clin Lab Haematol. 1990;12(1):87–95. [PubMed]
  • Kelleher BP, Broin SD. Microbiological assay for vitamin B12 performed in 96-well microtitre plates. J Clin Pathol. 1991 Jul;44(7):592–595. [PMC free article] [PubMed]

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