Mansour Fotouh R, Danielson Neil D
Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, Tanta University, El-Geish Street, the Medical Campus, Tanta, 31111, Egypt.
Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, United States.
Talanta. 2017 Aug 1;170:22-35. doi: 10.1016/j.talanta.2017.03.084. Epub 2017 Mar 29.
Dispersive liquid-liquid microextraction (DLLME) is a special type of microextraction in which a mixture of two solvents (an extracting solvent and a disperser) is injected into the sample. The extraction solvent is then dispersed as fine droplets in the cloudy sample through manual or mechanical agitation. Hence, the sample is centrifuged to break the formed emulsion and the extracting solvent is manually separated. The organic solvents commonly used in DLLME are halogenated hydrocarbons that are highly toxic. These solvents are heavier than water, so they sink to the bottom of the centrifugation tube which makes the separation step difficult. By using solvents of low density, the organic extractant floats on the sample surface. If the selected solvent such as undecanol has a freezing point in the range 10-25°C, the floating droplet can be solidified using a simple ice-bath, and then transferred out of the sample matrix; this step is known as solidification of floating organic droplet (SFOD). Coupling DLLME to SFOD combines the advantages of both approaches together. The DLLME-SFOD process is controlled by the same variables of conventional liquid-liquid extraction. The organic solvents used as extractants in DLLME-SFOD must be immiscible with water, of lower density, low volatility, high partition coefficient and low melting and freezing points. The extraction efficiency of DLLME-SFOD is affected by types and volumes of organic extractant and disperser, salt addition, pH, temperature, stirring rate and extraction time. This review discusses the principle, optimization variables, advantages and disadvantages and some selected applications of DLLME-SFOD in water, food and biomedical analysis.
分散液液微萃取（DLLME）是一种特殊的微萃取方法，该方法是将两种溶剂（萃取溶剂和分散剂）的混合物注入样品中。然后，通过手动或机械搅拌，萃取溶剂以细小液滴的形式分散在浑浊的样品中。因此，对样品进行离心以破坏形成的乳液，并手动分离萃取溶剂。DLLME中常用的有机溶剂是剧毒的卤代烃。这些溶剂比水重，因此会沉到离心管底部，这使得分离步骤变得困难。通过使用低密度溶剂，有机萃取剂会漂浮在样品表面。如果所选溶剂（如十一醇）的冰点在10 - 25°C范围内，则可以使用简单的冰浴使漂浮的液滴固化，然后将其从样品基质中转移出来；此步骤称为漂浮有机液滴固化（SFOD）。将DLLME与SFOD相结合，综合了两种方法的优点。DLLME - SFOD过程由常规液液萃取的相同变量控制。DLLME - SFOD中用作萃取剂的有机溶剂必须与水不混溶、密度较低、挥发性低、分配系数高以及熔点和冰点低。DLLME - SFOD的萃取效率受有机萃取剂和分散剂的类型及体积、加盐量、pH值、温度、搅拌速率和萃取时间的影响。本文综述了DLLME - SFOD在水、食品和生物医学分析中的原理、优化变量、优缺点以及一些选定的应用。
