Beta-carotene (BC) degradation was studied by liquid chromatography coupled to a quadrupole time of flight mass spectrometer. Throughout/After 21 days of dark storage, 56 nonvolatile degradants were chromatographically separated from pure BC crystal and their molecular formulas were identified. Their structure information was gained by comparing the fragments to a different, but structure-related compound. For example, a newly formed double bond position in dehydrogenated BC was determined by comparing the fragments between BC and dehydrogenated BC. One of their chemical structures was confirmed by comparing its precursor ion mass, retention time, isotopic ratio, and fragmentation to a pure trans-beta-apo-8'-apocarotenal. BC cleavage was observed on double bonds as well as single bonds in BC conjugation chain. PRACTICAL APPLICATION: As evidenced in this study, beta-carotene (BC) degradation is a spontaneous process initiated when the compound is exposed to air. The stoichiometric ratio of BC to oxygen is 1:0.03 at the first oxidation, therefore, only 0.3 mg oxygen or 1.2 mL air will degrade 10 mg BC, an average daily recommended intake. Not like in enzymatic BC degradation, spontaneous BC oxidation did not produce provitamin A, either in retina C20H38O or retinol C20H40O forms. For BC application in vitamin A deficiency, spontaneous BC oxidation should be avoided.

中文翻译：

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β-胡萝卜素降解化合物的鉴定及其结构解析的高分辨率精确质谱

β-胡萝卜素 (BC) 降解通过液相色谱法与四极杆飞行时间质谱仪进行了研究。整个/经过 21 天的暗储存，56 种非挥发性降解物从纯 BC 晶体中进行色谱分离，并确定了它们的分子式。它们的结构信息是通过将片段与不同但结构相关的化合物进行比较而获得的。例如，脱氢 BC 中新形成的双键位置是通过比较 BC 和脱氢 BC 之间的片段来确定的。通过将其前体离子质量、保留时间、同位素比和碎片与纯反式-β-apo-8'-apocar​​otenal 进行比较，证实了它们的化学结构之一。在 BC 共轭链中的双键和单键上都观察到了 BC 裂解。实际应用：正如本研究所证明的那样，β-胡萝卜素 (BC) 降解是一种自发过程，当该化合物暴露在空气中时就会开始。BC 与氧气的化学计量比在第一次氧化时为 1:0.03，因此，只有 0.3 毫克氧气或 1.2 毫升空气会降解 10 毫克 BC，这是平均每日推荐摄入量。与酶促 BC 降解不同，自发的 BC 氧化不产生维生素原 A，无论是视网膜 C20H38O 还是视黄醇 C20H40O 形式。对于维生素 A 缺乏症的 BC 应用，应避免 BC 的自发氧化。与酶促 BC 降解不同，自发的 BC 氧化不产生维生素原 A，无论是视网膜 C20H38O 还是视黄醇 C20H40O 形式。对于维生素 A 缺乏症的 BC 应用，应避免 BC 的自发氧化。与酶促 BC 降解不同，自发的 BC 氧化不产生维生素原 A，无论是视网膜 C20H38O 还是视黄醇 C20H40O 形式。对于维生素 A 缺乏症的 BC 应用，应避免 BC 的自发氧化。