Boonjob Warunya, Rosende María, Miró Manuel, Cerdà Víctor
Department of Chemistry, Faculty of Sciences, University of the Balearic Islands, Carretera de Valldemossa Km. 7.5, 07122, Palma de Mallorca, Illes Balears, Spain.
Anal Bioanal Chem. 2009 May;394(1):337-49. doi: 10.1007/s00216-009-2606-2. Epub 2009 Feb 4.
Two novel dynamic extraction approaches, the so-called sequential injection microcolumn extraction and sequential injection stirred-flow chamber extraction, based on the implementation of a sample-containing container as an external extraction reactor in a sequential injection network, are for the first time, optimized and critically appraised for fractionation assays. The three steps of the original Community Bureau of Reference (BCR) sequential extraction scheme have been performed in both automated dynamic fractionation systems to evaluate the extractability of Cr, Cu, Ni, Pb, and Zn in a standard reference material of coal fly ash (NIST 1633b). In order to find the experimental conditions with the greatest influence on metal leachability in dynamic BCR fractionation, a full-factorial design was applied, in which the solid sample weight (100-500 mg) and the extraction flow rate (3.0-6.0 mL min(-1)) were selected as experimental factors. Identical cumulative extractabilities were found in both sequential injection (SI)-based methods for most of assayed trace elements regardless of the extraction conditions selected, revealing that both dynamic fractionation systems, as opposed to conventional steady-state BCR extraction, are not operationally defined within the selected range of experimental conditions. Besides, the proposed automated SI assemblies offer a significant saving of operational time with respect to classical BCR test, that is, 3.3 h versus 48 h, for complete fractionation with minimum analyst involvement.
两种新颖的动态萃取方法，即所谓的顺序注射微柱萃取和顺序注射搅拌流室萃取，基于在顺序注射网络中将含样品容器用作外部萃取反应器的实现方式，首次针对分级分析进行了优化和严格评估。原始的标准物质与测量研究所（BCR）顺序萃取方案的三个步骤已在这两种自动动态分级系统中进行，以评估粉煤灰标准参考物质（NIST 1633b）中铬、铜、镍、铅和锌的可萃取性。为了找出对动态BCR分级中金属浸出率影响最大的实验条件，采用了全因子设计，其中选择固体样品重量（100 - 500毫克）和萃取流速（3.0 - 6.0毫升·分钟⁻¹）作为实验因素。在基于顺序注射（SI）的两种方法中，无论选择何种萃取条件，大多数被测微量元素的累积萃取率都相同，这表明与传统的稳态BCR萃取不同，这两种动态分级系统在所选择的实验条件范围内并非按操作定义。此外，与经典的BCR测试相比，所提出的自动SI组件显著节省了操作时间，即完成分级所需时间为3.3小时，而经典BCR测试为48小时，且分析师参与度最低。
