Faculty of Chemistry and Chemical Engineering, University of Maribor, Smetanova Ulica 17, SI-2000 Maribor, Slovenia.
Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna Pot 113, SI-1000 Ljubljana, Slovenia.
Molecules. 2021 Apr 23;26(9):2475. doi: 10.3390/molecules26092475.
When dealing with simple phenols such as caffeic acid (CA) and ferulic acid (FA), found in a variety of plants, it is very important to have control over the most important factors that accelerate their degradation reactions. This is the first report in which the stabilities of these two compounds have been systematically tested by exposure to various different factors. Forced degradation studies were performed on pure standards (-CA and -FA), dissolved in different solvents and exposed to different oxidative, photolytic and thermal stress conditions. Additionally, a rapid, sensitive, and selective stability-indicating gas chromatographic-mass spectrometric method was developed and validated for determination of -CA and -FA in the presence of their degradation products. -CA and -FA were confirmed as the only degradation products in all the experiments performed. All the compounds were perfectly separated by gas chromatography (GC) and identified using mass spectrometry (MS), a method that additionally elucidated their structures. In general, more protic solvents, higher temperatures, UV radiation and longer storage times led to more significant degradation (isomerization) of both -isomers. The most progressive isomerization of both compounds (up to 43%) was observed when the polar solutions were exposed to daylight at room temperature for 1 month. The method was validated for linearity, precision as repeatability, limit of detection (LOD) and limit of quantitation (LOQ). The method was confirmed as linear over tested concentration ranges from 1-100 mg L (rs were above 0.999). The LOD and LOQ for -FA were 0.15 mg L and 0.50 mg L, respectively. The LOD and LOQ for -CA were 0.23 mg L and 0.77 mg L, respectively.
在处理简单酚类物质（如咖啡酸（CA）和阿魏酸（FA））时，这些物质存在于多种植物中，控制加速其降解反应的最重要因素非常重要。这是首次系统测试这两种化合物稳定性的报告，通过暴露于各种不同的因素来进行。对纯标准品（-CA 和 -FA）进行了强制降解研究，这些标准品溶解在不同的溶剂中，并暴露于不同的氧化、光解和热应激条件下。此外，还开发并验证了一种快速、灵敏、选择性的稳定性指示气相色谱-质谱法，用于在存在降解产物的情况下测定 -CA 和 -FA。在所有进行的实验中，-CA 和 -FA 被确认为唯一的降解产物。所有化合物都通过气相色谱（GC）完美分离，并使用质谱（MS）进行鉴定，该方法还阐明了它们的结构。一般来说，质子性溶剂、较高的温度、UV 辐射和较长的储存时间会导致两种 -异构体的降解（异构化）更为显著。当极性溶液在室温下暴露于日光下 1 个月时，两种化合物的异构化最为显著（高达 43%）。该方法针对线性、精密度（重复性）、检测限（LOD）和定量限（LOQ）进行了验证。该方法在测试浓度范围内（1-100mg/L）表现出良好的线性关系（rs 均大于 0.999）。-FA 的 LOD 和 LOQ 分别为 0.15mg/L 和 0.50mg/L。-CA 的 LOD 和 LOQ 分别为 0.23mg/L 和 0.77mg/L。
