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Radiochemical assay for N/sup 5/-formyltetrahydrofolic acid (citrovorum factor) in serum and urine

Journal Article · · Anal. Biochem.; (United States)
N/sup 5/-Methyltetrahydrofolate, but not N/sup 5/-formyltetrahydrofolate, can be measured in biological fluids by ligand-binding radioassay. Therefore, in order to measure N/sup 5/-formyltetrahydrofolate by radioassay, it is chemically converted to N/sup 5/-methyltetrahydrofolate by acidification followed by reduction with borohydride. By this method, 70 to 113% of N/sup 5/-formyltetrahydrofolate added to serum and urine was recovered. The plasma clearance of the mixture of diastereoisomer of N/sup 5/-formyltetrahydrofolate (Leucovorin) following intravenous administration to two normal subjects was rapid for the first 30 min, but then plateaued and cleared very slowly over the next 90 min, most probably because of the accumulationn of the inactive isomer which was slowly excreted in the urine during this time period.
Research Organization:
New York Medical College, New York
OSTI ID:
6138379
Journal Information:
Anal. Biochem.; (United States), Journal Name: Anal. Biochem.; (United States) Vol. 94:2; ISSN ANBCA
Country of Publication:
United States
Language:
English

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