Abstract Iberin (IBR) is an isothiocyanate (ITC) with chemopreventive properties on different types of cancer. The need of quantifying IBR either in natural products or in food supplements makes the availability of suitable and stable analytical standards necessary. The choice of proper solvents for ITCs storage and experiment setup is a critical point due to ITCs reactivity. As IBR reference standard is sometimes supplied in ethanol, methanol is also frequently utilised as a solvent in ITCs analysis. A study on IBR stability in the most common solvents used in liquid chromatography and at different pH is presented. A fast UHPLC-PDA-ESI/MS analysis was used to separate IBR from degradation products, to monitor IBR stability at three temperatures and at different pH. The fastest degradation was observed in methanol/water mixture. IBR degraded always faster in methanol than in ethanol. At 20 °C, the degradation in ethanol and in water was comparable. At 30 °C and 40 °C the degradation in water was faster than either in ethanol or methanol. Ethyl thiocarbamate, methyl thiocarbamate and disubstituted thiourea degradation products, in ethanol, methanol and water respectively, were tentatively assigned. IBR was stable in acetonitrile and at acidic pH but it was unstable at alkaline pH.

中文翻译：

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溶剂对异硫氰酸酯 iberin 稳定性的影响研究

摘要 Iberin (IBR) 是一种异硫氰酸酯 (ITC)，对不同类型的癌症具有化学预防作用。需要对天然产品或食品补充剂中的 IBR 进行量化，因此需要合适且稳定的分析标准。由于 ITC 的反应性，为 ITC 存储和实验设置选择合适的溶剂是一个关键点。由于 IBR 参考标准有时以乙醇形式提供，因此在 ITC 分析中也经常使用甲醇作为溶剂。介绍了液相色谱中最常用溶剂和不同 pH 值下 IBR 稳定性的研究。使用快速 UHPLC-PDA-ESI/MS 分析将 IBR 与降解产物分离，以监测三种温度和不同 pH 下的 IBR 稳定性。在甲醇/水混合物中观察到最快的降解。IBR 在甲醇中的降解总是比在乙醇中更快。在 20 °C 时，乙醇和水中的降解程度相当。在 30 °C 和 40 °C 下，在水中的降解速度比在乙醇或甲醇中更快。硫代氨基甲酸乙酯、硫代氨基甲酸甲酯和二取代硫脲降解产物分别在乙醇、甲醇和水中进行了初步鉴定。IBR 在乙腈和酸性 pH 下稳定，但在碱性 pH 下不稳定。