High-performance liquid chromatographic separation of physiological folate monoglutamate compounds : Investigation of absorption and conversion of pteroyl-glutamic acid in the small intestine of the rat in situ

A new high-performance liquid chromatographic method to investigate many folate monoglutamate compounds was developed. This method employed a Cosmosil 5-Ph column eluted with 10 m M potassium phosphate buffer (pH 7.0) containing 1% methanol at a flow-rate of 1.0 ml/min. Under these conditions, almost all of the physiological folate monoglutamate compounds were effectively separated and determined within 22 min. By applying this method to investigate the absorption and conversion of pteroylglutamic acid in the rat small intestine, it was demonstrated that pteroylglutamic acid was converted into 5-methyltetrahydrofolic acid during absorption, and that the conversion was a saturable process, whereas unchanged pteroylglutamic acid was absorbed almost linearly in, proportion to the initial amount administered.