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实验表明,通过照射及游离基(过氧化苯甲酰)生成的联合作用可使维生素A快速破坏。[试剂]乙酸维生素A(1000IU/ml)、过氧化苯甲醛(16μmol/L)及间氯苯甲酸(16μmol/L)均用二甲苯和无水乙醇配制,并置-20℃避光保存。乙醇须先加KOH回流和重蒸馏。[方法]向盛有1.0ml过氧化苯甲酰或间氯苯甲酸(0～16μmol/L)的试管中,加入0.01ml乙酸维生素A(10IU),并置于距离带有紫色罩的汞灯9cm外,照射前开灯预热10分钟,再按不同时间进行照射。于照射前、后,在328nm波长处测其吸光度。另一实验是,向0.5ml人血浆中分别加入含0.5、1.0及2.0IU乙酸维生素A的乙醇溶液0.01ml,旋转混匀5分钟。加入11mol/L KOH水溶液和无水乙醇混合液(1:10V/V)0.5ml,旋转混匀,置60℃15分钟,冷后加1.0ml(16μmol/L)
Experiments show that the combination of irradiation and free radicals (benzoyl peroxide) can rapidly destroy vitamin A. [Reagents] Vitamin A acetate (1000 IU / ml), benzaldehyde peroxide (16 μmol / L) and m-chlorobenzoic acid (16 μmol / L) were prepared with xylene and absolute ethanol and stored at -20 ° C protected from light. Ethanol must first add KOH reflux and double distillation. [Method] To a test tube containing 1.0 ml of benzoyl peroxide or m-chlorobenzoic acid (0-16 μmol / L), 0.01 ml of vitamin A acetate (10 IU) was added and placed at a distance from the mercury lamp 9cm, the lamp warm-up before irradiation for 10 minutes, then according to different time irradiation. Before and after irradiation, absorbance was measured at a wavelength of 328 nm. In another experiment, 0.01 ml of an ethanol solution containing 0.5, 1.0 and 2.0 IU of vitamin A acetate was added to 0.5 ml of human plasma, respectively, and the mixture was spun for 5 minutes. Add 0.5ml of 11mol / L KOH aqueous solution and absolute ethanol mixture (1: 10V / V), mix by rotation and set at 60 ℃ for 15 minutes, add 1.0ml (16μmol / L)