Use of tube radial distribution of ternary mixed carrier solvents for introduction of absorption reagent for metal ion separation and online detection into capillary

Phase-separation multiphase flow: preliminary application to analytical chemistry

A two-phase separation mixed solution can undergo phase separation from one phase to two phases (i.e., upper and lower phases) in a batch vessel in response to changes in temperature and/or pressure. This phase separation is reversible. When the mixed solution undergoes a phase change while being fed into a microspace region, a dynamic liquid-liquid interface is formed, leading to a multiphase structure. This flow is called a phase-separation multiphase flow. Annular flow in a microspace, which is one such phase-separation multiphase flow, is interesting and has been applied to chromatography, extraction, reaction fields, and mixing. Here, research papers related to phase-separation multiphase flows-ranging from the discovery of the phenomenon to basic and technical research from the viewpoint of analytical science-are reviewed. In addition, the development of a new separation mode in a high-performance liquid chromatography system based on phase-separation multiphase flow is introduced.

Quantitative high-throughput approach to chalkophore screening in freshwaters

There is an increasing need to study the effects of trace metal micronutrients on microorganisms in natural waters. For Fe, small Fe-binding ligands called siderophores, which are secreted from cells and bind Fe with high affinity, have been demonstrated to modulate bioavailability of this critical nutrient. Relatively little is known about secretion of strong Cu-binding ligands (chalkophores) that may help organisms navigate the divide between Cu nutrition and toxicity. A barrier to environmental chalkophore research is a lack of literature on chalkophore analysis. Here we report the development of a quantitative, high-throughput approach to chalkophore screening based on a popular competitive-ligand binding assay for siderophores wherein ligands compete for metal in a chromogenic ternary complex of chrome azurol sulfonate-metal-surfactant. We developed the assay for high-throughput analysis using a microplate reader. The method performance is slightly better than that of comparable screening approaches for siderophores. We find that levels of other metals in natural samples may be capable of causing matrix interferences (a neglected source of analytical uncertainty in siderophore screening) and that for our method this can be overcome by standard additions. In this respect the high-throughput nature of the technique is a distinct advantage. To demonstrate practical use, we tested samples from field mesocosm studies that were set up with and without Cu and Fe amendments; we find trends in results that are logical in the environmental context of our application. This approach will be useful in areas such as risk assessment for a rapid survey of metal speciation and bioavailability; investigators who perform structural studies might also benefit from this approach to rapidly screen and select samples with high Fe/Cu binding capacity for further study.

Recent advances in open tubular capillary liquid chromatography

This review covers advances and applications of open tubular capillary liquid chromatography (OT-LC) over the period 2007–2018.

Tube Radial Distribution Chromatography on a Microchip Incorporating Microchannels with a Three-to-One Channel Confluence Point

We developed a capillary chromatography system using a phase-separated solvent mixture as a carrier solution--i.e., a water-hydrophilic/hydrophobic organic solvent mixture--which we call "tube radial distribution chromatography" (TRDC). Here, we attempted to apply the TRDC system to a microchip incorporating microchannels with a double T-junction for injection of analyte solution and a three-to-one, narrow-to-wide channel confluence point for tube radial distribution phenomenon (TRDP) at room temperature. A ternary mixed solvent of water, acetonitrile and ethyl acetate was used as a carrier solution. TRDP in the wide microchannel was examined using various flow rates, temperatures, and component solvent ratios. Successful observation was carried out using a fluorescence microscope-CCD camera. Model analytes perylene (hydrophobic) and Eosin Y (hydrophilic) were separated by flowing through the microchannel, without any treatment such as packed columns or coating, at room temperature (25°C).