Abstract
Summary
The assay of urinary formiminoglutamic acid (FIGLU) by paper or thin-layer chromatography for the diagnosis of folic acid deficiency has been difficult to quantitate because of the inability to separate FIGLU from a ninhydrin reactive compound in urine. This ninhydrin-positive interfering compound has been identified by chromatographic and microbiological means as the previously unsuspected amino acid alanine. Since the endogenous urinary excretion of alanine may equal or exceed that of FIGLU in normal and folic acid deficient subjects, the usefulness of paper and thinlayer chromatographic techniques is limited to qualitative estimation of FIGLU in urines with FIGLU concentrations of 150 μg/ml or more.
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