Department of Analytical Chemistry, University of Valencia, 46100 Burjassot, Valencia, Spain.
Department of Analytical Chemistry, University of Valencia, 46100 Burjassot, Valencia, Spain.
Anal Chim Acta. 2017 Aug 29;983:130-140. doi: 10.1016/j.aca.2017.06.024. Epub 2017 Jun 19.
With the aim of contributing to the development and improvement of microextraction techniques, a novel approach combining the principles and advantages of stir bar sorptive extraction (SBSE) and dispersive liquid-liquid microextraction (DLLME) is presented. This new approach, termed stir bar dispersive liquid microextraction (SBDLME), involves the addition of a magnetic ionic liquid (MIL) and a neodymium-core magnetic stir bar into the sample allowing the MIL coat the stir bar due to physical forces (i.e., magnetism). As long as the stirring rate is maintained at low speed, the MIL resists rotational (centrifugal) forces and remains on the stir bar surface in a manner closely resembling SBSE. By increasing the stirring rate, the rotational forces surpass the magnetic field and the MIL disperses into the sample solution in a similar manner to DLLME. After extraction, the stirring is stopped and the MIL returns to the stir bar without the requirement of an additional external magnetic field. The MIL-coated stir bar containing the preconcentrated analytes is thermally desorbed directly into a gas chromatographic system coupled to a mass spectrometric detector (TD-GC-MS). This novel approach opens new insights into the microextraction field, by using the benefits provided by SBSE and DLLME simultaneously, such as automated thermal desorption and high surface contact area, respectively, but most importantly, it enables the use of tailor-made solvents (i.e., MILs). To prove its utility, SBDLME has been used in the extraction of lipophilic organic UV filters from environmental water samples as model analytical application with excellent analytical features in terms of linearity, enrichment factors (67-791), limits of detection (low ng L), intra- and inter-day repeatability (RSD<15%) and relative recoveries (87-113%, 91-117% and 89-115% for river, sea and swimming pool water samples, respectively).
为了促进微萃取技术的发展和改进，提出了一种将搅拌棒吸附萃取（SBSE）和分散液相微萃取（DLLME）的原理和优点相结合的新方法。这种新方法称为搅拌棒分散液相微萃取（SBDLME），涉及向样品中添加磁性离子液体（MIL）和钕芯磁性搅拌棒，由于物理力（即磁性），使 MIL 涂覆在搅拌棒上。只要搅拌速度保持低速，MIL 就会抵抗旋转（离心）力，并以类似于 SBSE 的方式留在搅拌棒表面上。通过增加搅拌速度，旋转力超过磁场，MIL 以类似于 DLLME 的方式分散到样品溶液中。萃取完成后，停止搅拌，MIL 无需外加磁场即可返回搅拌棒。含有预浓缩分析物的 MIL 涂覆的搅拌棒直接热解吸到与质谱检测器耦合的气相色谱系统中（TD-GC-MS）。这种新方法通过同时利用 SBSE 和 DLLME 提供的优势，为微萃取领域提供了新的见解，例如自动热解吸和高表面积接触，而最重要的是，它能够使用定制溶剂（即 MIL）。为了证明其效用，SBDLME 已用于从环境水样中萃取疏水性有机紫外滤光剂作为模型分析应用，在线性、富集因子（67-791）、检测限（低 ng L）、日内和日间重复性（RSD<15%）和相对回收率（河、海和游泳池水样分别为 87-113%、91-117%和 89-115%）方面具有出色的分析性能。
