Abstract
Tetrahydrofolic acid (THFA) is oxidized easily by air to produce dihydrofolic acid, folic acid, p-aminobenzoylglutamate (PABG) and some others. Separation and determination of THFA were examined. THFA was separated with a liquid chromatograph using a column of DEAE-cellulose from other oxidized products. The fractionated THFA was treated with K_2Cr_2O_7 in acidic solution and resulted to produce an equivalent amount of PABG. The produced PABG was color-developed according to conventional method and then the amount of THFA was determined photometrically at 550 nm. PABG of "The Japanese Pharmacopoeia Standard" was used as standard.
