Advances in solvent-microextraction techniques

Since its inception in 1995, solvent-microextraction (SME) techniques for sample preparation have grown increasingly popular due to their simplicity, low cost, and adaptability to a wide variety of sample types and analytes. SME methods are used alone or as final clean-up and concentration techniques in preparing environmental, clinical, forensic, personal-care, pharmaceutical and food-product samples.There are two broad categories of SME: exposed-solvent and membrane-protected solvent techniques. The principal exposed-drop techniques include single-drop microextraction (SDME), headspace single-drop microextraction (HS-SDME), liquid-liquid microextraction (LLME), liquid-liquid-liquid microextraction (LLLME) and dispersive liquid-liquid microextraction (DLLME). The principal membrane-protected modes are hollow-fiber-protected 2-phase microextraction [HF(2)ME] and hollow-fiber-protected 3-phase microextraction [HF(3)ME].In recent years, interest in SME has increasingly turned to refinements of these modes for use in practical sample preparations. This has involved innovations (e.g., ionic liquids, ultrasonic-assisted emulsification, automation, and low-density solvents for DLLME).In this review, we explore these and other SME innovations appearing in the literature in the period from mid-2010 to mid-2012.

► Solvent microextraction has become an important tool for sample preparation.
► Solvent microextraction has simplicity, low cost and universal sample applicability.
► Innovations in solvent microextraction increasingly focused on refining methods.
► Innovations in solvent microextraction include ionic liquids and automation.
► Innovations in solvent microextraction include ultrasonic emulsification.