Single-Drop Microextraction

Since its discovery in 1995 by Dasgupta et al., and further implementation by Jeannot et al. in 1996, single-drop microextraction (SDME) has undergone a dramatic increase, as demonstrated by the significant number of developments and the plethora of applications that have extended this technique to almost every area, being nowadays one of the most popular miniaturised extraction techniques. The diversity of analytes, possibilities of combining SDME to detection techniques, the continuous improvements in extractant phases and the simplicity of operation, account for the spread acceptance of SDME. In this chapter, the different approaches available under the concept of extraction in a drop, extractant phases, both conventional and novel ones, as well as couplings of SDME with different detectors will be addressed. Relevant applications of SDME will be provided emphasizing analytical characteristics such as detection limits, precision and enrichment factors. Apart from the well-established modes of SDME such as direct immersion single-drop microextraction (DI-SDME), directly suspended drop microextraction (DSDME), headspace single-drop microextraction (HS-SDME), continuous flow microextraction (CFME) and liquid–liquid-liquid microextraction (LLLME), novel sophisticated approaches have arisen in the last years, such as drop-to-drop solvent microextraction (DDSME) or bubble-in-drop microextraction (BID), which provide new avenues for the continuous improvement of this technique.