Automation of dispersive liquid–liquid microextraction and related techniques. Approaches based on flow, batch, flow-batch and in-syringe modes

Abstract Liquid-phase microextraction has been one of the most studied sample pretreatment techniques in the last two decades. Apart from non-dispersive approaches, close attention has been also paid to microextraction methodologies based on emulsion formation using solvent-assisted dispersion, kinetic energy, or induction of solvent-oversaturation. These techniques exhibit attractive characteristics, such as simplicity, rapidness, versatility, high extraction efficiency, and environmental friendliness, and have stimulated significant progress in laboratory sample treatment. Moreover, further automation of these methods enables improvements in reproducibility and sample-throughput, as well as coupling with modern analytical instrumentation. Despite numerous reviews focused on dispersive liquid–liquid microextraction (DLLME) approaches, a critical survey on their automation is missing. Here, we present a comprehensive overview on the automation of DLLME and related techniques performed in flow, batch, flow-batch, and in-syringe modes. The challenges, advantages and drawbacks accompanying the different automation techniques are critically discussed, and an outlook on the perspectives of the automation strategies is presented.