The objective of this study was to develop a simple, sensitive and selective procedure for the preconcentration and determination of quercetin residues in Apium graveolens, Brassica oleracea, Spinacia oleracea, watercress, onion, and apple matrices. This novel method was developed on the basis of the dispersive-micro-solid phase extraction (D-μ-SPE) procedure based on a core–shell magnetic molecularly imprinted polymer (MMIP) in combination with high-performance liquid chromatography-ultraviolet (HPLC-UV). Variables affecting the quercetin extraction efficiency included pH, MIP dose, extraction contact time, elution organic solvent, and volume of organic solvent and were evaluated by the experimental central composite design (CCD). The obtained optimal parameters were as follows: pH (3.5), sorbent (12 mg), elution organic solvent and solvent volume (methanol, 0.2 mL), and elution time (22.0 min, without adding salt). The calibration curve was linear in the concentration range of 0.6–5500 μg L⁻¹ with the lower limits of detection found in the range of 0.113–0.117 μg L⁻¹, thereby revealing the high-sensitivity and -selectivity properties. The combination of D-μ-SPE and HPLC-UV could provide a method for the recovery of the analyte in various matrices at 22 min contact time with good reusability and excellent recoveries at four concentration levels (50, 100, 500, and 1000 μg L⁻¹), ranging between 95.44 and 106.89% (relative standard deviation <6.0%). Based on competitive sorption experiments, the synthesized MMIP displays higher selectivity toward quercetin compared to non-imprinted polymers (NIPs) and other sorbents.

中文翻译：

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基于核-壳磁性分子印迹聚合物的分散微固相萃取简单，选择性地检测植物和食品样品中的槲皮素†

这项研究的目的是开发一种简单，灵敏和选择性的程序，用于浓集，油菜，菠菜，菠菜中槲皮素残留的预浓缩和测定。，豆瓣菜，洋葱和苹果基质。这种新方法是在基于核-壳磁性分子印迹聚合物（MMIP）结合高效液相色谱-紫外线（HPLC）的分散微固相萃取（D-μ-SPE）程序的基础上开发的-紫外线）。影响槲皮素提取效率的变量包括pH，MIP剂量，提取接触时间，洗脱有机溶剂和有机溶剂的体积，并通过实验性中央复合设计（CCD）进行了评估。获得的最佳参数如下：pH（3.5），吸附剂（12 mg），洗脱有机溶剂和溶剂量（甲醇，0.2 mL）和洗脱时间（22.0分钟，不添加盐）。校准曲线在0.6–5500μgL ^-1的浓度范围内呈线性最低检测限为0.113–0.117μgL ^-1，从而显示出高灵敏度和高选择性的特性。D-μ-SPE和HPLC-UV的组合可以提供一种在22分钟的接触时间以多种基质（50、100、500和1000μg）良好的重用性和出色的回收率在各种基质中回收分析物的方法L ^-1），介于95.44和106.89％之间（相对标准偏差<6.0％）。基于竞争性吸附实验，与非印迹聚合物（NIP）和其他吸附剂相比，合成的MMIP对槲皮素具有更高的选择性。