Here we show that a closed pneumatic microvalve on a PDMS chip can serve as a semipermeable membrane under an applied potential, enabling current to pass through while blocking the passage of charged analytes. Enrichment of both anionic and cationic species has been demonstrated, and concentration factors of ~70 have been achieved in just 8 s. Once analytes are concentrated, the valve is briefl...

been widely researched as surface and deep soil treatment techniques (Figure 1). For certain practical situations, such as house foundations on expansive soil, mixing is not possible. Current research has shown that chemical treatment using a potential difference to transport chemical ions between bespoke electrodes can overcome such problems, whilst achieving the desired results. However, a ma...

Although electrokinetic effects are not new, only recently have they been investigated for possible use in energy conversion devices. We recently reported the electrokinetic generation of molecular hydrogen from rapidly flowing liquid water microjets [Duffin et al. J. Phys. Chem. C 2007, 111, 12031]. Here, we describe the use of liquid water microjets for direct conversion of electrokinetic ene...

The two-fluid flow is produced by the combined effects of electroosmotic force in a conducting liquid and pressure gradient force in a non-conducting liquid. The Poisson-Boltzmann and Navier-Stokes equations are solved analytically; and the effects of governing parameters are examined. Poiseuille number increases with increasing the parameters involved. In the absence of pressure gradient, the ...

Electrokinetic remediation technology is one of the developing technologies that offers great promise for the cleanup of soils contaminated with heavy metals. However, the performance of an electrokinetic remediation system depends on the interaction of a complex set of interrelated system variables and parameters. Many of these interactions were addressed in this study by incorporating geochem...

In this study, an on-line stacking capillary electrophoresis (CE) method, reverse-mode field amplified sample injection equipped with sweeping micellar electrokinetic chromatography (RMFASI-sweeping MEKC), was established for direct determination of uroporphyrin and coproporphyrin in human urine. Porphyrins playing a very important role in the biosynthesis of heme, chlorophyll and other importa...

In this paper, we report a novel method for fabricating ion-selective membranes in poly(dimethylsiloxane) (PDMS)/glass-based microfluidic preconcentrators. Based on the concept of capillary valves, this fabrication method involves filling a lithographically patterned junction between two microchannels with an ion-selective material such as Nafion resin; subsequent curing results in a high aspec...

Abstract A sensitive method for the determination of citrate and malate in sub-microliter samples of soil solution is described. The organic acids were derivatized with a pyrene reagent (1-pyrenebutanoic acid hydrazide) and analysed by micellar electrokinetic chromatography separation. The citrate and malate derivatives were detected within 10 min by using a fluorescence detector with a broad e...