Centro de Química da Madeira, Centro de Ciências Exactas e da Engenharia da Universidade da Madeira, 9000-390 Funchal, Portugal.
J Chromatogr A. 2012 Oct 19;1260:154-63. doi: 10.1016/j.chroma.2012.08.082. Epub 2012 Aug 30.
This paper reports on the development and optimization of a modified Quick, Easy, Cheap Effective, Rugged and Safe (QuEChERS) based extraction technique coupled with a clean-up dispersive-solid phase extraction (dSPE) as a new, reliable and powerful strategy to enhance the extraction efficiency of free low molecular-weight polyphenols in selected species of dietary vegetables. The process involves two simple steps. First, the homogenized samples are extracted and partitioned using an organic solvent and salt solution. Then, the supernatant is further extracted and cleaned using a dSPE technique. Final clear extracts of vegetables were concentrated under vacuum to near dryness and taken up into initial mobile phase (0.1% formic acid and 20% methanol). The separation and quantification of free low molecular weight polyphenols from the vegetable extracts was achieved by ultrahigh pressure liquid chromatography (UHPLC) equipped with a phodiode array (PDA) detection system and a Trifunctional High Strength Silica capillary analytical column (HSS T3), specially designed for polar compounds. The performance of the method was assessed by studying the selectivity, linear dynamic range, the limit of detection (LOD) and limit of quantification (LOQ), precision, trueness, and matrix effects. The validation parameters of the method showed satisfactory figures of merit. Good linearity (Rvalues2>0.954; (+)-catechin in carrot samples) was achieved at the studied concentration range. Reproducibility was better than 3%. Consistent recoveries of polyphenols ranging from 78.4 to 99.9% were observed when all target vegetable samples were spiked at two concentration levels, with relative standard deviations (RSDs, n=5) lower than 2.9%. The LODs and the LOQs ranged from 0.005 μg mL(-1) (trans-resveratrol, carrot) to 0.62 μg mL(-1) (syringic acid, garlic) and from 0.016 μg mL(-1) (trans-resveratrol, carrot) to 0.87 μg mL(-1) ((+)-catechin, carrot) depending on the compound. The method was applied for studying the occurrence of free low molecular weight polyphenols in eight selected dietary vegetables (broccoli, tomato, carrot, garlic, onion, red pepper, green pepper and beetroot), providing a valuable and promising tool for food quality evaluation.
本文报道了一种改良的快速、简便、廉价、有效、耐用和安全（QuEChERS）提取技术的开发和优化，该技术结合了净化分散固相萃取（dSPE），作为一种新的、可靠和强大的策略，可提高选定食用蔬菜中游离低分子量多酚的提取效率。该过程涉及两个简单的步骤。首先，将匀浆样品用有机溶剂和盐溶液提取和分配。然后，使用 dSPE 技术进一步提取和净化上清液。将蔬菜的最终澄清提取物在真空下浓缩至近干，并用初始流动相（0.1%甲酸和 20%甲醇）溶解。通过配备光电二极管阵列（PDA）检测系统和专门设计用于极性化合物的三功能高强度硅胶毛细管分析柱（HSS T3）的超高效液相色谱（UHPLC）实现了从蔬菜提取物中分离和定量游离低分子量多酚。通过研究选择性、线性动态范围、检测限（LOD）和定量限（LOQ）、精密度、准确度和基质效应来评估方法的性能。该方法的验证参数显示出令人满意的优良指标。在所研究的浓度范围内，（+）-儿茶素在胡萝卜样品中）达到了良好的线性（Rvalues2>0.954）。重现性优于 3%。当所有目标蔬菜样品在两个浓度水平下加标时，观察到多酚的回收率在 78.4%至 99.9%之间，相对标准偏差（RSD，n=5）低于 2.9%。LOD 和 LOQ 范围为 0.005μgmL-1（反式白藜芦醇，胡萝卜）至 0.62μgmL-1（丁香酸，大蒜）和 0.016μgmL-1（反式白藜芦醇，胡萝卜）至 0.87μgmL-1（（+）-儿茶素，胡萝卜），具体取决于化合物。该方法用于研究八种选定的食用蔬菜（西兰花、番茄、胡萝卜、大蒜、洋葱、红辣椒、青椒和甜菜根）中游离低分子量多酚的存在情况，为食品质量评价提供了一种有价值和有前途的工具。
