On-line sample preconcentration by LVSEP-FASI with simple voltage control on Y-channel chips.

To eliminate complicated voltage controls for highly sensitive microchip electrophoresis (MCE) analyses on the basis of combining two online sample preconcentration techniques, large-volume sample stacking with an electroosmotic flow (EOF) pump (LVSEP) and field-amplified sample injection (FASI), cross-channel microchips and a multichannel high-voltage power supply were replaced to Y-channel chips and a conventional power supply designed for capillary electrophoresis, respectively. By simple switching of the electric circuit after the LVSEP-FASI sample enrichments, the focused analytes could be separated during anodic migration in a separation channel. In the LVSEP-FASI analysis of fluorescein using the Y-channel microchip, the maximum sensitivity enhancement factor (SEF) of 7400 was achieved, resulting in a 30-fold detectability increase compared to the conventional LVSEP.

A thin-layer solid-phase extraction-liquid film elution technique used for the enrichment of polycyclic aromatic hydrocarbons in water.

In this article, we propose a novel microsolid-phase extraction and elution technique, which we called the thin-layer solid-phase extraction-liquid film elution technique. The thin-layer solid-phase extraction phase is an octadecylsilylated sol gel- coated porous silica thin film prepared on the outer wall of a test tube, which has a larger surface area for the extraction of the target compounds compared to a conventional solid-phase microextraction phase. After optimization of the extraction procedure for five types of polycyclic aromatic hydrocarbons, the liquid film elution technique was investigated.

Nonaqueous capillary gel electrophoretic analysis of metal nanoclusters in polymeric-DMSO-Li systems.

In this study, we investigated a combination of nonaqueous CE with capillary gel electrophoresis to achieve highly efficient analysis of metal nanoclusters. In the nonaqueous capillary gel electrophoresis (NACGE), PVA and hydroxypropyl methylcellulose were dissolved in DMSO. In addition, to enhance the entanglement of the polymer chains, Li ions were also added.

Highly Sensitive Analysis in Capillary Electrophoresis Using Large-volume Sample Stacking with an Electroosmotic Flow Pump Combined with Field-amplified Sample Injection.

To achieve highly sensitive analysis without labor-intensive experimental procedures in capillary electrophoresis (CE), large-volume sample stacking with an electroosmotic flow pump (LVSEP)-field-amplified sample injection (FASI) was combined with a dynamic coating technique. In this study, poly(vinyl pyrrolidone) (PVP) was employed for the dynamic coating additive. Since a standard fluorescent dye, fluorescein, was well concentrated in a conventional LVSEP, the PVP dynamically-coated capillaries can be also applied to the LVSEP-FASI analysis.

Combination of large-volume sample stacking with an electroosmotic flow pump with field-amplified sample injection on cross-channel chips.

A combination of two online sample concentration techniques, large-volume sample stacking with an electroosmotic flow (EOF) pump (LVSEP) and field-amplified sample injection (FASI), was investigated in microchip electrophoresis (MCE) to achieve highly sensitive analysis. By applying reversed-polarity voltages on a cross-channel microchip, anionic analytes injected throughout a microchannel were first concentrated on the basis of LVSEP, followed by the electrokinetic stacking injection of the analytes from a sample reservoir by the FASI mechanism. As well as the voltage application, a pressure was also applied to the sample reservoir in LVSEP-FASI.

On-line coupling of sample preconcentration by LVSEP with gel electrophoretic separation on T-channel chips.

To achieve an on-line coupling of the sample preconcentration by a large-volume sample stacking with an electroosmotic flow pump (LVSEP) with microchip gel electrophoresis (MCGE), a sample solution, a background solution for LVSEP and a sieving solution for MCGE were loaded in a T-form channel and three reservoirs on PDMS microchips. By utilizing the difference in the flow resistance of the two channels, a low-viscosity sample and a viscous polymer solution were easily introduced into the LVSEP and MCGE channels, respectively. Fluorescence imaging of the sequential LVSEP-MCGE processes clearly demonstrated that a faster stacking of anionic fluorescein and successive introduction into the MCGE channel can be carried out on the T-channel chip.

Simple and Rapid Immobilization of Coating Polymers on Poly(dimethyl siloxane)-glass Hybrid Microchips by a Vacuum-drying Method.

A simple and rapid vacuum-drying modification method was applied to several neutral and charged polymers to obtain coating layers for controlling electroosmotic flow (EOF) and suppressing sample adsorption on poly(dimethyl siloxane) (PDMS)-glass hybrid microchips. In the vacuum-dried poly(vinylpyrrolidone) coating, the electroosmotic mobility (μeo) was suppressed from +2.1 to +0.

Effects of divalent cations on bovine testicular hyaluronidase catalyzed transglycosylation of chondroitin sulfates.

Glycosaminoglycans were prepared as salts of different divalent cations and tested as donors in bovine testicular hyaluronidase catalyzed transglycosylation reactions. All of the metal cations examined had similar binding efficiency of divalent cations to hyaluronan. However, cations bound with different efficiencies to chondroitin sulfate species and the differences were marked in the case of chondroitin 6-sulfate; the numbers of cations bound per disaccharide unit were estimated to be 0.

Preparation of open tubular solid-phase extraction column with 5-amino-8-hydroxyquinoline-modified gold nanoparticle phase for the enrichment of heavy metal ions.

A 5-amino-8-hydroxyquinoline (AHQ)-modified gold nanoparticle (GNP) layer was fabricated on an inner wall of a silica capillary column by alternatively passing a citrate-stabilized GNP solution and an AHQ solution in a repeating fashion. The observations by a field emission scanning electron microscope showed that the thickness of the resulting GNP layer was about 0.15 microm.

Determination of tin by resin-suspension electrothermal atomic absorption spectrometry after enrichment as the complex with ammonium pyrrolidinedithiocarbamate.

A resin-phase extraction method has been optimized for the trace determination of tin(II) by ETAAS. Tin(II) was extracted on a finely divided anion exchange resin as the complex with ammonium pyrrolidinedithiocarbamate (APDC). The resin was collected on a membrane filter and then dispersed in 1.

Determination of thallium in potassium chloride and electrolyte replenishers by electrothermal atomic absorption spectrometry.

Thallium in potassium chloride and electrolyte replenishers was determined by electrothermal atomic absorption spectrometry (ETAAS) with direct injection of a resin suspension. Thallium(III) was extracted on fine particles of a cellulose nitrate resin (CNR) from dilute HCl (pH 1.6) in the presence of ammonium pyrrolidine-1-carbodithioate.

An enrichment method of molybdenum on a cellulose nitrate resin for the determination by electrothermal atomic absorption spectrometry coupled with the resin suspension injection.

Cellulose derivative resin (CDR) suspensions containing resin particles of cellulose nitrate (CDR(CN)), cellulose acetate (CDR(CA)), or cellulose triacetate (CDR(CTA)) were prepared as the sorbent for resin suspension injection (RSI) electrothermal atomic absorption spectrometry (ETAAS), in which fine resin particles holding a desired trace element were directly injected into the graphite tube as the suspension. To compare the sorption ability, the distribution ratios of the Mo(VI)-phenylfluorone complex were measured between the aqueous phase and the sorbents, including the CDRs mentioned above and the finely divided anion exchange resin (AR). The results showed that the sorption ability decreases in the following order: CDR(CN) > or = AR > CDR(CA) > or = CDR(CTA).

A glycomic approach to proteoglycan with a two-dimensional polysaccharide chain map.

Glycosaminoglycan chains were liberated from proteoglycans (bovine lung, tracheal cartilage, and cerebrum) by successive digestion with actinase and with cellulase from Aspergillus niger, which has endo-beta-xylosidase activity. The glycosaminoglycan chains were fluorescence-labeled with 2-aminopyridine after digestion with Streptomyces hyaluronidase. The resulting pyridylamino-glycosaminoglycans, including heparan sulfate, chondroitin sulfate/dermatan sulfate, and heparin, were separated by high-performance liquid chromatography.

Determination of V(IV) and V(V) by electrothermal atomic absorption spectrometry following selective solid-phase extraction and the study on the change in the oxidation state of vanadium species in seawater during the sample storage.

The changes in the oxidation state of vanadium in artificial and natural seawater samples were studied by electrothermal atomic absorption spectrometry (ETAAS) with a direct injection of a resin suspension. V(IV) and V(V) were extracted as the complex with Chromazurol B and with N-cinnamoyl-N-2,3-xylylhydroxylamine, respectively, using a suspension of an anion-exchange resin and determined by ETAAS independently. The detection limits of both methods were 0.