title: Direct microtitre plate enzyme immunoassay of folic acid without heat denaturation of serum.
abstract: A new and simple method for enzyme immunoassay of folic acid (FA) has been developed, which does not require extraction or heat denaturation of serum. FA-free serum for standards was prepared by a new immunosorbent technique as conventional methods were unsuccessful. The detection limit of the assay is 0.05 ng/ml. Intra- and interassay variabilities ranged between 5-13.3%. Analytical recoveries obtained after spiking with different amounts of FA ranged between 93-110%. We eliminated the interference of endogenous folate binding protein--a major problem in direct FA assay by incubating serum samples (or standards) with FA-HRP conjugate in antibody coated plates at 50 degrees C. Comparison of our data with results obtained by microbiological assay and also by heating samples in alkaline buffer showed good correlation.
authors.affiliation: Indian Statistical Institute, Calcutta, India.
authors.forename: J
authors.initials: J
authors.lastname: Das Sarma
authors.forename: C
authors.initials: C
authors.lastname: Duttagupta
authors.forename: E
authors.initials: E
authors.lastname: Ali
authors.forename: T K
authors.initials: TK
authors.lastname: Dhar
mesh_terms: D002352:Carrier Proteins / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D058973:Folate Receptors, GPI-Anchored; D005492:Folic Acid / Q000097:blood*; D006358:Hot Temperature; D006801:Humans; D011489:Protein Denaturation; D011956:Receptors, Cell Surface; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D002352:Carrier Proteins; D058973:Folate Receptors, GPI-Anchored; D011956:Receptors, Cell Surface; D005492:Folic Acid