Introduction and Review of Liquid-Liquid Micro-Extraction (DLLME) Method, Development and Applications in Sample Preparation and Extraction

Dispersive liquid-liquid microextraction (DLLME) is a novel sample-preparation technique that provides high enrichment factors from the low volume of aqueous samples. This method has gained wide acceptance due to several advantages, including being inexpensive, fast, easy to develop, easy to operate with a high enrichment factor, and consuming low volume of organic solvent, which has made it available to almost all analytical laboratories. This review focuses on the improvements that have been made in the DLLME since its introduction in 2006. In this study, the use of DLLME with simultaneous derivatization of analytes, the combination of DLLME with other sample preparation techniques, and the replacement of toxic chlorinated solvents with low toxicity hydrocarbons, alcohols, and ionic liquids were described. Moreover, this paper seeks to describe the use of DLLME to pre-concentrate metal ions and further modifications of this newly developed technique. It briefly describes the various applications of DLLME for several groups of analytes, including pesticides, drugs, phenols, and other compounds, and finally, some limitations and future trends are anticipated.