On-line sample preconcentration technique based on a dynamic pH junction in CE-amperometric detection for the analysis of biogenic amines in urine.

It is difficult to detect biogenic amines (BAs) in biological fluids because of their very low concentrations. In this paper, we reported an on-line sample preconcentration method in CE-amperometric detection (CE-AD) based on a dynamic pH junction, and a concentration enhancement of approximately 100-fold was achieved compared with the classical CE-AD methods in the simultaneous analysis of six BAs in urine (dopamine, epinephrine, norepinephrine, tyramine, tryptamine, and serotonin). The technique is proposed based on the sharp pH change generated at the boundary between an acidic sample and the basic BGE zone.

Sensitive analysis of aminoglycoside antibiotics via hyphenation of transient moving substitution boundary with field-enhanced sample injection in capillary electrophoresis.

A novel field-enhanced sample injection coupled with transient moving substitution boundary method in capillary electrophoresis was developed for aminoglycoside antibiotic (AG) analysis using 18-crown-6-tetracarboxylic acid (18C6H4) as a pseudostationary phase. Results indicated that the stacking mechanism of moving substitution boundary relied on the substitution reaction between 18C6H4-bonded AG complexes and Na(+) at the substitution boundary. The stacking mechanism as well as important parameters governing pre-concentration and separation have been investigated in order to obtain maximum resolution and sensitivity.

Sensitive measurement of polyols in urine by capillary zone electrophoresis coupled with amperometric detection using on-column complexation with borate.

Little is known about human polyol metabolism, but recent studies indicate that abnormal polyol concentrations in body fluids are related to several diseases. In this study, a rapid and sensitive method for the determination of seven major polyols in urine including two groups of polyol isomers, C5-polyols (Rib+Arb+Xyl) and C6-polyols (Sor+Gal+Man), was developed using capillary zone electrophoresis coupled with amperometric detection (CZE-AD). The effects of the working electrode potential, pH, running buffer components and concentrations, separation voltage and injection times were investigated.

Ultrasensitive detection of bacteria by microchip electrophoresis based on multiple-concentration approaches combining chitosan sweeping, field-amplified sample stacking, and reversed-field stacking.

In this paper we describe an on-chip multiple-concentration method combining chitosan (CS) sweeping, reversed-field stacking, and field-amplified sample stacking for highly efficient detection of bacteria. Escherichia coli was selected as a model bacterium to investigate the efficiency of this multiple-concentration method. CS was the most suitable sweeping agent for microchip electrophoresis, replacing the usually used cetyltrimethylammonium bromide for capillary electrophoresis.

Microchip electrophoresis of bacteria using lipid-based liquid crystalline nanoparticles.

The aggregation and adhesion of bacterial cells is a serious disadvantage for electrophoretic separations of bacteria. In this study, lipid-based liquid crystalline nanoparticles were used as a pseudostationary phase to minimise the bacterial aggregation and adsorption to the inner walls of microchannels. Lactobacillus delbrueckii subsp.

Nonenzymatic glucose sensor based on over-oxidized polypyrrole modified Pd/Si microchannel plate electrode.

A silicon microchannel plate (MCP) array electrode modified with over-oxidized polypyrrole (OPPy) has been fabricated to detect glucose. The morphology and structure of the electrode are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The OPPy modified silicon MCP array electrode exhibits high electrocatalytic activity as well as excellent selectivity to the electrochemical oxidation of glucose.