Recent advances and future prospects of mesofluidic lab-on-a-valve platforms in analytical sciences--a critical review.

Miniaturization and automation in analytical sciences have evolved tremendously over the past decade within the framework of green analytical chemistry. This manuscript outlines the unrivalled merits of advanced flow methodology capitalizing on mesofluidic platforms for the simplification and acceleration of the overall analytical process. Introduced back in 2000, the Lab-on-a-Valve concept (LOV), allied to sequential injection analysis, has emerged as an appealing downscaled analytical tool for pressure-driven sampling at the low μL level. Not the least, for advanced on-chip sample processing involving renewable micro-solid phase extraction (so-called bead injection analysis), non-chromatographic speciation or chemical vapor generation using programmable flow, for optical and electrochemical detection on-chip including optosensing approaches, or as a front end to modern detection equipment or column separation systems. It is the intention of this work to offer the authors' own critical vision as to where the field of LOV is being directed on the basis of the survey of the current state-of-the art of mesofluidic systems and identify what are the major cutting-edge challenges to be yet undertaken and what opportunities are offered by LOV for real-world applications that might not be at present tackled by lab-on-a-chip microfluidic approaches.