IMPROVEMENTS IN THE ANALYSIS OF REDUCED FOLATE MONOGLUTAMATES AND FOLIC-ACID IN FOOD BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

A reversed-phase high-performance liquid chromatographic method with f luorescence and ultraviolet detection was used to evaluate the differe nt steps in folate analysis to detect and quantify the most abundant f olate forms naturally present in foods. Rapid heat extraction by micro wave heating and an enzymatic deconjugation with hog kidney conjugase and chicken pancreas is presented. The extracts were purified with str ong anion-exchange cartridges before injection. The combined use of as corbic acid and mercaptoethanol in the extraction step noticeably impr oved the stability of tetrahydrofolate, making it also possible to ana lyze some of the most labile folate vitamers. Tetrahydrofolate was als o shown to be easily degraded during the deconjugation step. The compo unds 5-methyltetrahydrofolate and, to a lesser extent, 5-formyltetrahy drofolates were also found as important vitamers in foods. In addition , folic acid and 10-formylfolic acid could be determined with the desc ribed method.