Oellig Claudia
Institute of Food Chemistry, University of Hohenheim, Garbenstrasse 28, 70599 Stuttgart, Germany.
J Chromatogr A. 2016 May 6;1445:19-26. doi: 10.1016/j.chroma.2016.03.082. Epub 2016 Mar 31.
Propolis is a very complex mixture of substances that is produced by honey bees and is known to be a rather challenging matrix for residue analysis. Besides resins, flavonoids and phenols, high amount of wax is co-extracted resulting in immense matrix effects. Therefore a suitable clean-up is crucial and indispensable. In this study, a reliable solid phase extraction (SPE) clean-up was developed for pesticide residue analysis in propolis. The clean-up success was quickly and easily monitored by high-performance thin-layer chromatography with different detection possibilities. The final method consists of the extraction of propolis with acetonitrile according to the QuEChERS method followed by an effective extract purification on dual-layer SPE cartridges with spherical hydrophobic polystyrene-divinylbenzene resin/primary secondary amine as sorbent and a mixture of toluene/acetone (95:5, v/v) for elution. Besides fat-soluble components like waxes, flavonoids, and terpenoids, more polar compounds like organic acids, fatty acids, sugars and anthocyanins were also removed to large extent. Method performance was assessed by recovery experiments at spiking levels of 0.5 and 1mg/kg (n=5) for fourteen pesticides that are relevant for propolis. Mean recoveries determined by HPLC-MS against solvent standards were between 40 and 101%, while calculation against matrix-matched standards provided recoveries of 79-104%. Precision of recovery, assessed by relative standard deviations, were below 9%. Thus, the developed dual-layer SPE clean-up enables the reliable pesticide residue analysis in propolis and provides a suitable alternative to time-consuming clean-up procedures proposed in literature.
蜂胶是蜜蜂产生的一种非常复杂的物质混合物，已知是残留分析中颇具挑战性的基质。除了树脂、黄酮类化合物和酚类物质外，还会共提取大量蜡质，从而产生巨大的基质效应。因此，合适的净化至关重要且不可或缺。在本研究中，开发了一种可靠的固相萃取（SPE）净化方法用于蜂胶中农药残留分析。通过具有不同检测可能性的高效薄层色谱法可快速简便地监测净化效果。最终方法包括根据QuEChERS方法用乙腈提取蜂胶，随后在双层SPE柱上进行有效的提取物净化，该柱以球形疏水聚苯乙烯 - 二乙烯基苯树脂/伯仲胺为吸附剂，用甲苯/丙酮（95:5，v/v）混合物洗脱。除了蜡质、黄酮类化合物和萜类化合物等脂溶性成分外，有机酸、脂肪酸、糖类和花青素等极性更强的化合物也被大量去除。通过对14种与蜂胶相关的农药在0.5和1mg/kg加标水平下进行回收率实验（n = 5）来评估方法性能。相对于溶剂标准品，通过HPLC-MS测定的平均回收率在40%至101%之间，而相对于基质匹配标准品计算的回收率为79 - 104%。通过相对标准偏差评估的回收率精密度低于9%。因此，所开发的双层SPE净化方法能够可靠地分析蜂胶中的农药残留，并为文献中提出的耗时净化程序提供了合适的替代方法。
