Department of Chemistry, Faculty of Science, University of the Balearic Islands, Carretera de Valldemosa km. 7.5, E-07122, Palma de Mallorca, Illes Balears, Spain.
Anal Chim Acta. 2010 Jan 18;658(1):41-8. doi: 10.1016/j.aca.2009.10.051. Epub 2009 Oct 29.
Dynamic flow-through extraction/fractionation methods have recently drawn much attention as appealing alternatives to the batchwise steady-state counterparts for the evaluation of environmentally available pools of potentially hazardous trace elements in solid matrices. The most critical weakness of flow-based column approaches lies in the small amount of solid that can be handled, whereby their applicability has been merely limited to date to the extraction of trace elements in highly homogeneous solid substrates; otherwise the representativeness of the test portion might not be assured. To tackle this limitation, we have devised an automated flow-through system incorporating a specially designed extraction column with a large volume capacity, wherein up to 2 g of solid sample could be handled without undue backpressure. The assembled flow setup was exploited for fast screening of potentially hazardous trace elements (namely, Cd, Cr, Cu, Pb, and Zn) in highly inhomogeneous municipal solid waste incineration (MSWI) bottom ashes. The pools of readily mobilizable metal forms were ascertained using the Toxicity Characteristic Leaching Procedure (TCLP) based on the usage of 0.1 mol L(-1) CH(3)COOH as leachant and analysis of extracts by inductively coupled optical emission spectrometry. The application of a two-level full factorial (screening) design revealed that the effect of sample fluidization primarily but other experimental factors such as the solid to liquid ratio and extractant flow rate significantly influenced the leachability of given elements in raw bottom ashes at the 0.05 significance level. The analytical performance of the novel flow-based method capitalized on fluidized-bed extraction was evaluated in terms of accuracy, through the use of mass balance validation, reproducibility and operational time as compared to batchwise extraction and earlier flow injection/sequential injection microcolum-based leaching tests.
动态流动萃取/分级方法最近作为批处理稳态方法的替代品引起了广泛关注，可用于评估固体基质中潜在危险痕量元素的环境可利用池。基于流动的柱方法的最关键弱点在于可处理的固体量少，迄今为止，其应用仅限于高度均匀的固体基质中痕量元素的提取；否则，测试部分的代表性可能无法得到保证。为了解决这个限制，我们设计了一种自动化的流动系统，该系统结合了一个具有大容量的特殊设计的萃取柱，其中可以处理高达 2 克的固体样品，而不会产生不必要的背压。组装的流动装置被用于快速筛选高不均匀性城市固体废物焚烧（MSWI）底灰中潜在危险的痕量元素（即 Cd、Cr、Cu、Pb 和 Zn）。使用基于使用 0.1 mol L(-1) CH(3)COOH 作为浸出剂的毒性特征浸出程序（TCLP），并通过电感耦合光发射光谱分析提取物，确定了易于移动的金属形态的池。使用两级全因子（筛选）设计表明，样品流化的影响主要是，但其他实验因素，如固液比和萃取剂流速，在 0.05 显著性水平下显著影响原始底灰中给定元素的浸出率。新型基于流动的方法的分析性能通过使用质量平衡验证，与批处理提取相比，在准确性、重现性和操作时间方面进行了评估。
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