Gregory J F, Sartain D B, Day B P
J Nutr. 1984 Feb;114(2):341-53. doi: 10.1093/jn/114.2.341.
A procedure was developed for the quantitation of the major folacin compounds present in foods and other biological materials. Extraction conditions were selected to provide conversion of 10-formyltetrahydrofolic acid (10-HCO-H4folic acid) to 5-HCO-H4folic acid. Polyglutamyl folates were deconjugated with hog kidney conjugase. The resulting folacin monoglutamates were separated by reverse-phase high performance liquid chromatography after extract purification on an anion exchange column. Detection of H4folic acid and its substituted derivatives was performed by monitoring the native fluorescence of the reduced folates in the acidic mobile phase. Folic acid, H2folic acid and also H4folic acid were measured fluorometrically by using an oxidative postcolumn derivatization system in series with the first fluorometer. Detection limits ranged from 0.03 to 2.3 pmol/100 microliters injection for the various folates. The validity of the method was supported by recovery and fluorescence spectral studies and by comparison with Lactobacillus casei assays for a variety of samples. Analysis of rat liver following a single pulse dose of 3H-labeled folic acid indicated large differences between the patterns of radiolabeled and endogenous folates.
已开发出一种用于定量测定食品和其他生物材料中主要叶酸化合物的方法。选择的提取条件可使10-甲酰基四氢叶酸（10-HCO-H4叶酸）转化为5-HCO-H4叶酸。用猪肾共轭酶使聚谷氨酰叶酸脱共轭。在阴离子交换柱上对提取物进行纯化后，通过反相高效液相色谱法分离得到的叶酸单谷氨酸盐。通过监测酸性流动相中还原叶酸的天然荧光来检测H4叶酸及其取代衍生物。叶酸、H2叶酸以及H4叶酸通过与第一台荧光计串联的氧化柱后衍生系统进行荧光测定。各种叶酸的检测限为0.03至2.3 pmol/100微升进样量。该方法的有效性通过回收率和荧光光谱研究以及与多种样品的干酪乳杆菌测定法的比较得到了支持。对单次脉冲剂量的3H标记叶酸后的大鼠肝脏进行分析表明，放射性标记叶酸和内源性叶酸的模式存在很大差异。
