Development of an ultra-micro sample injector for gas chromatography using an ink-jet microchip.

An ultra-micro sample injector for gas chromatography (GC) was developed. An ink-jet microchip, originally used for industrial recorder, was modified at the edge near to an orifice, and fixed into the GC. In order to evaluate the characteristics of this injector, a sample injector and a thermal conductive detector (TCD) were connected directly, while water was used as the test sample.

Spatial resolution improvement of scanning microscopy based on thermal lens spectroscopy with a total-internal-reflection arrangement.

In scanning microscopy by total internal reflection with thermal lens spectroscopy, its spatial resolution depends on the distance between the sample and a converging lens, which corresponds to the objective lens in an ordinary optical microscope. It was found that the resolution was best when the signal induced by the thermal lens effect was maximum. The distance was precisely adjusted by monitoring the signal intensity, and the resolution became twice better than that previously reported.

An integrated microfluidic device in polyester for electrophoretic analysis of amino acids.

A precolumn reaction chamber was integrated into a polyester microfluidic device with a miniaturized detection system. The reaction chamber was designed to be a zigzag channel, 70 microm in width, 8 mm in length, followed by a wider straight channel, 150 microm in width, 2 mm in length. The detection system is composed of an embedded light-emitting diode (LED), an integrated optical fiber, and a photomultiplier tube (PMT).

A compactly integrated laser-induced fluorescence detector for microchip electrophoresis.

A simple and easy-to-use integrated laser-induced fluorescence detector for microchip electrophoresis was constructed and evaluated. The fluid channels and optical fiber channels in the glass microchip were fabricated using standard photolithographic techniques and wet chemical etching. A 473 nm diode-pumped laser was used as the excitation source, and the collimation and collection optics and mirrors were discarded by using a multimode optical fiber to couple the excitation light straight into the microchannel and placing the microchip directly on the top of the photomultiplier tube.

Detection method for microchip separations.

The features of analytical systems utilizing microfluidic devices, especially detection methods, are described. Electrochemical detection (EC), laser-induced fluorescence (LIF), mass spectrometry (MS), and chemical luminescence (CL) methods are covered. EC enables detection without labeling and has been used in recent years because of its low cost and sensitivity.

Development of a scanning microscopy by total internal reflection coupled with thermal lens spectroscopy.

Non-destructive measurement of a small region on a solid/liquid interface is of great importance in physical chemistry and biochemistry, especially in the research of thin films and cell membranes. Optical methods for surface analysis with high lateral resolution are suitable methods for monitoring them. We now report a new scanning optical microscopic method to which total internal reflection coupled with a thermal lens technique was introduced.

Chiral separation with ligand-exchange micellar electrokinetic chromatography using a D-penicillamine-copper(II) ternary complex as chiral selector.

D-Penicillamine is demonstrated for the first time as a chiral ligand for the enantioseparation of dansyl amino acids based on ligand-exchange micellar electrokinetic chromatography (LE-MEKC). Copper(II) was used as the central ion in the ternary complex. The effect of surfactant on the resolution was significant.

Cyclodextrin-modified monolithic columns for resolving dansyl amino acid enantiomers and positional isomers by capillary electrochromatography.

We describe beta- and gamma-cyclodextrins (beta- and gamma-CD)-modified monolithic columns prepared by sol-gel process and chemical modifications. The monolithic silica column was fabricated inside a fused-silica capillary with 100 microm inner diameter by sol-gel process. The monolithic silica matrix was chemically modified chiral selectors of beta- or gamma-CDs with a spacer of 3-glycidoxypropyltrimethoxysilane by on-column reactions.

Evaluation of lateral resolution of scanning surface microscopy by total internal reflection with thermal lens effect.

We have developed a novel method for in situ and non-destructive surface analyses, or a total internal reflection with thermal lens spectroscopy (TIR-TLS), which has sufficient sensitivity to monitor phenomena in thin films, such as lipid bilayers. In this study, we applied TIR-TLS to microscopy for surface analyses, and we experimentally obtained its lateral resolution using the edge of a chromium film made by a photolithography technique. The obtained resolution was 20 microm, which was 60% of the diameter of an excitation beam at the interface.

Monitoring nano-flow rate of water by atomic emission detection using helium radio-frequency plasma.

Recently, high-performance nano-scale flow pumping systems have been developed for micro and miniaturized analysis systems. A novel device capable of measuring and monitoring nanoliter scale flow rates has been required for the further development of the pumping system. In this study, an atomic emission detector using helium radio-frequency plasma (RFP-AED) was used for the measurement of the nanoliter scale flow rate of water by quantitatively detecting the emission from hydrogen in the water molecules.

Comparison of enantioseparations using Cu(II) complexes with L-amino acid amides as chiral selectors or chiral stationary phases by capillary electrophoresis, capillary electrochromatography and micro liquid chromatography.

In this paper we report that Cu(II) complexes with L-amino acid amides were used as chiral selectors for enantioseparation by capillary electrophoresis, capillary electrochromatography (CEC) and micro liquid chromatography using chemically modified monolithic columns. The enantioselectivity, enantiomer migration order, and the performance have been compared when different chiral selectors were used in these modes. L-Enantiomers showed longer retention times than D-forms in both CEC and LC modes.

Comparison of three different anionic surfactants for the separation of hydrophobic compounds by nonaqueous capillary electrophoresis.

The effect of the three different surfactants, sodium dodecyl sulfate (SDS), diethylhexyl sodium sulfosuccinate (AOT), and taurodexycholic acid sodium salt (STDC) on the nonaqueous capillary electrophoretic separations of hydrophobic compounds were compared with formamide containing 20 mM K2HPO4 as electrolyte solvent. Separations of all selected uncharged hydrophobic compounds, e.g.

Chemically modified chiral monolithic silica column prepared by a sol-gel process for enantiomeric separation by micro high-performance liquid chromatography.

In this work a new type of chiral monolith silica column was developed for the chiral separation by micro high-performance liquid chromatography (micro-HPLC). The chiral monolith column with a continuous skeleton and a large through-pore structure was prepared inside a capillary of 100 microm I.D.

Photo-response assisted enantiomer separations on an azobenzene-modified gamma-cyclodextrin stationary phase in micro-HPLC.

The photo-responses of the retention and enantioseparation of several optical isomers were evaluated using an azobenzene-modified gamma-cyclodextrin stationary phase (Az gamma-CDSP) in micro-HPLC. UV light irradiation induced a decrease in the retention and the chiral selectivity for N-(3,5-dinitrobenzoyl)-1-phenylethylamine (DNBPEA) and N-(3,5-dinitrobenzoyl)-1-(1-naphtylethyl)amine (DNBNEA), while an increase was induced for dansylphenylalanine (DnsPhe) using a mixture of methanol and aqueous phosphate buffer as the mobile phase. No changes in the retention and the enantiomer separation of benzoin were observed with UV light irradiation.