STUDIES ON FOOD ADDITIVES (ERYTHORBIC ACID) ABSORPTION IN MAN

赤藓酸（ErA）是l -抗坏血酸（AsA）的立体异构体之一。它具有与AsA类似的抗氧化特性，在日本被广泛用作食品中的抗氧化剂，没有剂量限制，因为动物试验表明它没有毒性作用。我们的人体生物监测研究结果表明，在同时口服剂量后，ErA的吸收和/或排泄可能少于AsA。然而，必须进行进一步的测试来证实这些发现。由于食品添加剂在生物样品中的浓度很低，我们首先尝试用高效毛细管电泳（HPCE）同时测定这两种酸。方法：使用含有离子表面活性剂（如SDS）胶束的缓冲溶液，采用胶束电动色谱（MEKC）的高效液相色谱方法，同时测定标准溶液和加有AsA和ErA的尿液样品中的AsA和ErA。将10nl的样品虹吸到毛细管中。该方法使用500 mm* 75mm的熔融石英柱和含有50 mm SDS （pH 11.0）的10mM硼酸盐缓冲液。分离电压为15kV，分离电压为25‰。在λ =265nm处测定紫外吸收。结果：标准溶液中AsA峰在5.7min迁移，ErA峰在6.1 min迁移。在尿样中，AsA峰在5.2 min迁移，ErA峰在5.6min迁移。分离在8分钟内完成，与肌酐峰（4.9min）和尿酸峰（5.8min）无重叠。AsA和ErA的回收率分别为98%和88%。

Erythorbic acid (ErA) is one of the stereoisomers of L-ascorbic acid (AsA). It possesses antioxidative properties similar to AsA and is used widely in Japan as an antioxidant in foods with no dosage limitation, because animal tests show that it has no toxic effects. The results of our biological monitoring studies in humans showed that absorption and/or excretion of ErA may be less than that of AsA after administration of simultaneous oral doses. However, further tests must be done to confirm these findings. Because the concentration of food additives in biological samples is very low, we first tried to simultaneously determine these two acids by high performance capillary electrophoresis (HPCE).Methods : The HPCE procedure called micellar electro kinetic chromatography (MEKC) using a buffer solution containing micelles of ionic surfactant (e.g. SDS), has been used to simultaneously determine AsA and ErA in standard solutions and urine samples spiked with AsA and ErA.10nl of sample was siphoned into the capillary. The proposed method used a 500 mm*75mum i.d. fused silica column and a 10mM borate buffer containing 50 mM SDS (pH 11.0). The determination was carried out using a 15kV separation voltage at 25ﾟC.The UV absorption was measured at lambda=265nm.Results : The AsA peak migrated at 5.7min and the ErA peak at 6.1 min in the standard solution. In the urine samples, the AsA peak migrated at 5.2 min and the ErA peak at 5.6min. The separation was complete in eight minutes and there was no overlapping with the creatinine peak (4.9min) and uric acid peak (5.8min). The recovery of AsA and ErA from the urine was 98% and 88%.respectively.