Evaluation of pteroylglutamic acid and n-5-methyltetrahydrofolic acid reference standards in a new "No-Boil" radioassay for serum folate.
Serum folate, pteroylglutamic acid standards, and N-5-methyltetrahydrofolate standards extract differently during sample preparation for radiometric assay. B/B0 values for each material were determined before and after an alkaline extraction procedure. Serum folate most closely resembled N-5-methyltetrahydrofolate standards in that it exhibited a slightly greater ability to displace iodinated folate derivative in competition for beta-lactoglobulin binder. Pteroylglutamic acid standards displaced folate derivative less well, so that serum folate values were lower than when N-5-methyltetrahydrofolate was used as the standard material.
D005492:Folic Acid / Q000097:blood* / Q000592:standards; D006801:Humans; D011869:Radioligand Assay / Q000379:methods*; D011933:Reagent Kits, Diagnostic; D012015:Reference Standards; D013763:Tetrahydrofolates / Q000592:standards*
D011933:Reagent Kits, Diagnostic; D013763:Tetrahydrofolates; D005492:Folic Acid; C005984:5-methyltetrahydrofolate