Determination of Phenolic Compounds in Red Sweet Pepper (Capsicum annuum L.) Using a Modified QuEChERS Method and UHPLC-MS/MS Analysis and Its Relation to Antioxidant Activity

In the present work, a fast, easy and efficient analytical method was developed and validated for the determination of phenolic compounds (4-hydroxybenzoic, vanillic, caffeic, p-coumaric, sinapic, ferulic and ellagic acids, and naringenin) in red sweet pepper. Extraction of phenolic compounds was carried out using the quick, easy, cheap, effective, rugged and safe (QuEChERS) method, followed by separation and detection using ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). When the acetate version of the QuEChERS method was used, higher amounts of the phenolic compounds were extracted. In the dispersive solid phase extraction (d-SPE) clean-up step, combination of 50 mg of octadecylsilane (C18) and 7.5 mg of graphitized carbon black (GCB), resulted in the greatest removal of interferents, especially carotenoids, without significant retention of phenolic compounds. The recoveries for the proposed method were 82-103%, the limits of quantification were 2-150 µg kg-1, and the precision values expressed in terms of relative standard deviation (RSD) were ≤ 15%. The method developed was successfully applied to the analysis of different red sweet pepper cultivars.

本研究开发并验证了一种快速、简便且高效的分析方法，用于测定红甜椒中的酚类物质，包括4-羟基苯甲酸、香草酸、咖啡酸、对香豆酸、芥子酸、阿魏酸、鞣花酸以及柚皮素。酚类物质的提取采用快速、简便、廉价、高效、稳定且安全（QuEChERS）方法，随后通过超高效液相色谱-串联质谱（UHPLC-MS/MS）完成分离与检测。当使用QuEChERS乙酸盐版本时，可提取得到更高含量的酚类物质。在分散固相萃取（d-SPE）净化步骤中，采用50 mg十八烷基硅烷（C18）与7.5 mg石墨化炭黑（GCB）的组合，可最大程度去除干扰物（尤其是类胡萝卜素），且不会显著保留酚类物质。本方法的回收率为82%~103%，定量限为2~150 μg·kg⁻¹，以相对标准偏差（RSD）表示的精密度值≤15%。所开发的方法已成功应用于不同红甜椒品种的分析检测。