Díez C, Traag W A, Zommer P, Marinero P, Atienza J
Laboratory of Physic-Chemical Analysis, ITACyL, Agrarian Technological Institute of Castilla y León, Ctra. Burgos, km.119, 47071 Valladolid, Spain.
J Chromatogr A. 2006 Oct 27;1131(1-2):11-23. doi: 10.1016/j.chroma.2006.07.046. Epub 2006 Aug 9.
An acetonitrile/partitioning extraction and "dispersive solid-phase extraction (SPE)" method that provides high quality results with a minimum number of steps and a low solvent and glassware consumption was published in 2003. This method, suitable for the analysis of multiple classes of pesticide residues in foods, has been given an acronymic name, QuEChERS, that reflects its major advantages (quick, easy, cheap, effective, rugged, safe). In this work, QuEChERS method, which was originally created for vegetable samples with a high amount of water, was modified to optimise the extraction of a wide range of herbicides in barley. Then, it was compared with known conventional multi-residue extraction procedures such as the Luke method, which was simplified and shortened by eliminating the Florisil clean-up (mini Luke) and the ethyl acetate extraction, which involves a subsequent clean-up by gel permeation chromatography (GPC) and which is the official extraction method used by some of European authorities. Finally, a simple acetone extraction was carried out to check the differences with the other three methods. Extracts were analysed by gas chromatography-time-of-flight mass spectrometry (GC-TOF/MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Mini Luke was significantly more effective for the extraction of non-polar and medium-polar compounds, but the best recoveries for polar compounds were achieved by QuEChERS and ethyl acetate methods. QuEChERS was the only method that provided an overall recovery value of 60-70% for non-, medium- and polar compounds, with some exceptions due to co-eluted matrix interferences. Clean-up by dispersive SPE was effective and did not differ so much with ethyl acetate extracts considering that QuEChERS clean-up step is much easier and less time-consuming. As a conclusion, it resulted to be the most universal extraction method by providing a well-defined phase separation without dilution and achieving acceptable recoveries in average including the extraction of the always difficult acidic herbicides. However, recoveries were not as good as required for validation purposes suggesting that residues are prone to strong matrix interactions in dry samples as barley and further method adaptation incrementing solvent strength, extraction time or more acidic or basic conditions is needed in order to achieve a complete extraction.
2003年发表了一种乙腈/分配萃取和“分散固相萃取(SPE)”方法,该方法步骤最少,溶剂和玻璃器皿消耗低,能提供高质量结果。这种适用于分析食品中多类农药残留的方法被赋予了一个首字母缩写名称QuEChERS,它体现了该方法的主要优点(快速、简便、廉价、有效、耐用、安全)。在这项工作中,最初为含水量高的蔬菜样品创建的QuEChERS方法经过改进,以优化大麦中多种除草剂的萃取。然后,将其与已知的传统多残留萃取程序进行比较,如通过省去弗罗里硅土净化步骤(微型Luke法)简化和缩短的Luke法,以及涉及随后通过凝胶渗透色谱法(GPC)净化的乙酸乙酯萃取法,后者是一些欧洲当局使用的官方萃取方法。最后,进行了简单的丙酮萃取以检查与其他三种方法的差异。提取物通过气相色谱-飞行时间质谱(GC-TOF/MS)和液相色谱-串联质谱(LC-MS/MS)进行分析。微型Luke法对非极性和中等极性化合物的萃取效果明显更好,但QuEChERS法和乙酸乙酯法对极性化合物的回收率最高。QuEChERS是唯一一种对非极性、中等极性和极性化合物总体回收率达到60 - 70%的方法,不过由于共洗脱基质干扰存在一些例外情况。考虑到QuEChERS净化步骤更简便且耗时更少,分散固相萃取净化效果良好,与乙酸乙酯提取物的差异不大。总之,它是最通用的萃取方法,能实现明确的相分离且无需稀释,平均回收率可接受,包括对一直较难萃取的酸性除草剂的萃取。然而,回收率未达到验证要求,这表明在大麦等干燥样品中,残留容易与基质发生强烈相互作用,需要进一步调整方法,增加溶剂强度、萃取时间或采用更酸性或碱性的条件,以实现完全萃取。