Analytical potential of mesofluidic lab-on-a-valve as a front end to column-separation systems

The lab-on-a-valve (LOV) integrated microdevice has recently attracted much attention as a functional mesofluidic platform for programmable, pressure-driven flow as compared to lab-on-a-chip counterparts. We review the current state of the art of LOV as a versatile front end to column-separation techniques, namely, liquid chromatography (LC), gas chromatography (GC) and capillary electrophoresis (CE) for automatic mesofluidic handling at the low-microliter level, in-line sample processing and introducing the appropriate form of the analyte into the instrument for separation or detection. The open architecture of the LOV monolith unit has been to date exploited to accommodate micro solid-phase extraction in a renewable fashion, the so-called bead-injection analysis, encompassing reversed-phase materials and molecularly imprinted polymers, and in-valve microscale affinity chromatography. A plethora of interfaces have been recently devised for reliable injection of minute, well-defined volumes of analyte-containing solutions into LC,GC or CE We illustrate these applications with representative examples in environmental and bioanalytical arenas. (C) 2010 Elsevier Ltd. All rights reserved.