Simplified Mercury Extraction from Coal Fly Ash for Quantification of Total Mercury by ELISA-based Immunoassay.

A simplified two-step mercury extraction procedure enabled the selective and reproducible mercury recovery from actual coal fly ash (CFA). The optimized extraction procedure involving conventional enzyme-linked immunosorbent assay (ELISA)-based immunoassay allowed the ultra-sensitive quantification of total mercury content in CFA. The total mercury content of 41 CFA samples were successfully determined using the above-mentioned method, and the results were in agreement with those obtained by standard instrumental analysis (thermal decomposition atomic absorption spectrometry) within a 15% coefficient of variation.

Label-free impedimetric immunoassay for trace levels of polychlorinated biphenyls in insulating oil.

A rapid, ultrasensitive, and practical label-free impedimetric immunoassay for measuring trace levels of total polychlorinated biphenyls (PCBs) in insulating oil was developed. First, we developed a novel monoclonal antibody (RU6F9) for PCBs by using a designed immunogen and characterized its binding affinity for a commercial mixtures of PCBs and its main congeners. A micro comblike gold electrode was fabricated, and the antibody was covalently immobilized on the electrode through a self-assembled monolayer formed by dithiobis-N-succinimidyl propionate.

Pretreatment method for immunoassay of polychlorinated biphenyls in transformer oil using multilayer capillary column and microfluidic liquid-liquid partitioning.

Polychlorinated biphenyls (PCBs) are persistent organic pollutants that are present in the insulating oil inside a large number of transformers. To aid in eliminating PCB-contaminated transformers, PCBs in oil need to be measured using a rapid and cost-effective analytical method. We previously reported a pretreatment method for the immunoassay of PCBs in oil using a large-scale multilayer column and a microchip with multiple microrecesses, which permitted concentrated solvent extraction.

Trace-level mercury ion (Hg2+) analysis in aqueous sample based on solid-phase extraction followed by microfluidic immunoassay.

Mercury is considered the most important heavy-metal pollutant, because of the likelihood of bioaccumulation and toxicity. Monitoring widespread ionic mercury (Hg(2+)) contamination requires high-throughput and cost-effective methods to screen large numbers of environmental samples. In this study, we developed a simple and sensitive analysis for Hg(2+) in environmental aqueous samples by combining a microfluidic immunoassay and solid-phase extraction (SPE).

Microfluidic heavy metal immunoassay based on absorbance measurement.

A simple and rapid flow-based multioperation immunoassay for heavy metals using a microfluidic device was developed. The antigen-immobilized microparticles in a sub-channel were introduced as the solid phase into a main channel structures through a channel flow mechanism and packed into a detection area enclosed by dam-like structures in the microfluidic device. A mixture of a heavy metal and a gold nanoparticle-labeled antibody was made to flow toward the corresponding metal through the main channel and make brief contact with the solid phase.

Shape of the liquid-liquid interface in micro counter-current flows.

We investigated the shape of the liquid-liquid interface in micro counter-current flows formed within microchannels. The pressure balance at the interface was calculated based on the interface geometry. Although the shape should be an arc under laminar flow, a large deformation near the center of the microchannel was observed.

Microchip-based plasma separation from whole blood via axial migration of blood cells.

Highly efficient cell-free plasma separation from 200 µL of human whole blood was realized via axial migration of blood cells and cross-flow filtration in a microchip. Although various analyses of small volumes of blood have been reported, a large volume of blood is necessary for obtaining blood cells and plasma for the conventional plasma separation technique of centrifugation. A highly efficient plasma separation method using small volumes of blood without hemolysis is an important issue.

Analysis of polychlorinated biphenyls in transformer oil by using liquid-liquid partitioning in a microfluidic device.

Polychlorinated biphenyls (PCBs) that are present in transformer oil are a common global problem because of their toxicity and environmental persistence. The development of a rapid, low-cost method for measurement of PCBs in oil has been a matter of priority because of the large number of PCB-contaminated transformers still in service. Although one of the rapid, low-cost methods involves an immunoassay, which uses multilayer column separation, hexane evaporation, dimethyl sulfoxide (DMSO) partitioning, antigen-antibody reaction, and a measurement system, there is a demand for more cost-effective and simpler procedures.

Sensitive gas analysis system on a microchip and application for on-site monitoring of NH3 in a clean room.

A portable, highly sensitive, and continuous ammonia gas monitoring system was developed with a microfluidic chip. The system consists of a main unit, a gas pumping unit, and a computer which serves as an operation console. The size of the system is 45 cm width × 30 cm depth × 30 cm height, and the portable system was realized.

Parallel multiphase microflows: fundamental physics, stabilization methods and applications.

Parallel multiphase microflows, which can integrate unit operations in a microchip under continuous flow conditions, are discussed. Fundamental physics, stabilization methods and some applications are shown.

Pressure balance at the liquid-liquid interface of micro countercurrent flows in microchips.

An interfacial pressure balance model was proposed and verified for the elucidation of the physical mechanism of micro countercurrent flow in a hydrophilic-hydrophobic selective-modification microchannel. We considered the conditions of the microflow phase separation, where the phase separation entails a single phase flow in each output of the microchannel. In this pressure balance model, the pressure difference between the two phases due to pressure loss in each phase is balanced by the Laplace pressure generated by the interfacial tension at the liquid-liquid interface between the separated phases.

Flow velocity profile of micro counter-current flows.

Flow velocity profiles of micro counter-current flow of aqueous and butylacetate phases in a microchannel having a width of 100 microm were measured by micro particle image velocimetry. In order to analyze the hydrodynamic characteristics of the counter-current flow, we derived a simple analytical model for the velocity profile. When flow rates of the aqueous and organic phases were 0.