Hiroyoshi Minakuchi - Academia.edu (original) (raw)

Papers by Hiroyoshi Minakuchi

Research paper thumbnail of Monolithic silica capillary column extraction of methamphetamine and amphetamine in urine coupled with thin-layer chromatographic detection

Forensic Toxicology

A monolithic silica capillary column was first developed in Japan in 2001 as a new tool for bette... more A monolithic silica capillary column was first developed in Japan in 2001 as a new tool for better liquid chromatographic separation. The column is made of C18-bonded monolithic silica packed into a capillary glass tube (0.20 mm i.d.). In this study, we used this column for solid-phase extraction of methamphetamine (MA) and amphetamine (AP) in urine. Chromatographic separation was achieved by thin-layer chromatography (TLC) with double-spray detection of each spot. For extraction of amphetamines in urine, samples were mixed with phosphate buffer (pH 3.0, containing 20mM sodium octanesulfate), and the analytes were adsorbed to the column by passing the mixture through it. They were then eluted with a 10-μl volume of ethyl acetate and directly spotted onto a TLC plate. After development, the detection of MA was performed with Simon’s reagent. The plate was air-dried, and then over-sprayed with fluorescamine reagent for detection of AP. A fluorescent spot of AP was observed at 365 nm u...

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Research paper thumbnail of Monolithic silica columns with various skeleton sizes and through-pore sizes for capillary liquid chromatography

Journal of Chromatography A, 2002

Reduction of through-pore size and skeleton size of a monolithic silica column was attempted to p... more Reduction of through-pore size and skeleton size of a monolithic silica column was attempted to provide high separation efficiency in a short time. Monolithic silica columns were prepared to have various sizes of skeletons (approximately 1-2 microm) and through-pores (approximately 2-8 microm) in a fused-silica capillary (50-200 microm I.D.). The columns were evaluated in HPLC after derivatization to C18 phase. It was possible to prepare monolithic silica structures in capillaries of up to 200 microm I.D. from a mixture of tetramethoxysilane and methyltrimethoxysilane. As expected, a monolithic silica column with smaller domain size showed higher column efficiency and higher pressure drop. High external porosity (> 80%) and large through-pores resulted in high permeability (K = 8 x 10(-14) -1.3 x 10(-12) m2) that was 2-30 times higher than that of a column packed with 5-mirom silica particles. The monolithic silica columns prepared in capillaries produced a plate height of about 8-12 microm with an 80% aqueous acetonitrile mobile phase at a linear velocity of 1 mm/s. Separation impedance, E, was found to be as low as 100 under optimum conditions, a value about an order of magnitude lower than reported for conventional columns packed with 5-microm particles. Although a column with smaller domain size generally resulted in higher separation impedance and the lower total performance, the monolithic silica columns showed performance beyond the limit of conventional particle-packed columns under pressure-driven conditions.

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Research paper thumbnail of Oxynitride glass and fibers thereof

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Research paper thumbnail of Effect of polyethylene glycol on pore structure and separation efficiency of silica-based monolithic capillary columns

Journal of chromatography. A, Jan 15, 2016

Monolithic silica materials (first unclad monolith rods, then monolithic capillary columns) were ... more Monolithic silica materials (first unclad monolith rods, then monolithic capillary columns) were prepared using various amounts of polyethylene glycols (PEGs) with different molecular weight (MW). The monolith rods were used to examine the mesoporosity by argon physisorption technique, and the macroporosity by mercury intrusion porosimetry. Subsequently, silica-based monolithic capillary columns with an inner diameter of 100 μm were produced using the same preparation conditions as used for the rods. The results obtained with the monolith rods showed the following important findings: (1) it is feasible to fabricate monolithic silica rods possessing macropore size of 0.5-1.4 μm by tuning the amount of PEGs (independently of the MW), whereas the macropore volume and the mesoporosity remain similar. (2) the smallest macropore size (0.5 μm) rod prepared with PEG having a MW=20,000g/mol provided a narrower macropore size distribution than with PEG with MW=10,000g/mol. The monolithic capi...

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Research paper thumbnail of Novel Method for DNA Isolation Using High-throughput Monolithic Silica Gel Column in Combination with Anti-chaotropic Effect

Chemistry Letters, Dec 5, 2006

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Research paper thumbnail of Channel Unit for Liquid Chromatograph

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Research paper thumbnail of Oxynitride glass and the fiber thereof

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Research paper thumbnail of Adsorption Column for Purifying Body Fluid

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Research paper thumbnail of Nueva columna de tipo monolítico para separaciones rápidas en HPLC

Industria Farmaceutica Equipos Procesos Y Tecnologia, 2000

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Research paper thumbnail of Immobilization of peptide-containing compounds on metal hydroxide gels

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Research paper thumbnail of Chromatographic Properties of Miniaturized Silica Rod Columns

Journal of High Resolution Chromatography, 1998

ABSTRACT

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Research paper thumbnail of Monolithic Silica Columns for HPLC, Micro-HPLC, and CEC

Journal of High Resolution Chromatography, 2000

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Research paper thumbnail of Three Dimensional Structure and Liquid Transport Behavior of Siloxane Gels with Co-continuous Macropores

MRS Proceedings, 2004

... Gels with Co-continuous Macropores Haruko Saito 1 , Kazuki Nakanishi 1 , Kazuyuki Hirao 1 , H... more ... Gels with Co-continuous Macropores Haruko Saito 1 , Kazuki Nakanishi 1 , Kazuyuki Hirao 1 , Hiroshi Jinnai 2 , Kei Morisato 3 , Hiroyoshi Minakuchi 3 ... Sci. 27 (2004) 887. [12] Y. Nishikawa, H. Jinnai, T. Koga, T. Hashimoto, ST Hyde, Langmuir 14 (1998) 1242. ...

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Research paper thumbnail of Short communication performance of octadecylsilylated monolithic silica capillary columns of 530 microm inner diameter in HPLC

Journal of Separation Science, Dec 1, 2006

Monolithic silica capillary columns were successfully prepared in a fused silica capillary of 530... more Monolithic silica capillary columns were successfully prepared in a fused silica capillary of 530 microm inner diameter and evaluated in HPLC after octadecylsilylation (ODS). Their efficiency and permeability were compared with those of columns pakked with 5-microm and 3-microm ODS-silica particles. The monolithic silica columns having different domain sizes (combined size of through-pore and skeleton) showed 2.5-4.0-times higher permeability (K= 5.2-8.4 x 10(-14) m2) than capillary columns packed with 3-mm particles, while giving similar column efficiency. The monolithic silica capillary columns gave a plate height of about 11-13 microm, or 11 200-13 400 theoretical plates/150 mm column length, in 80% methanol at a linear mobile phase velocity of 1.0 mm/s. The monolithic column having a smaller domain size showed higher column efficiency and higher pressure drop, although the monolithic column with a larger domain size showed better overall column performance, or smaller separation impedance (E value). The larger-diameter (530 microm id) monolithic silica capillary column afforded a good peak shape in gradient elution of proteins at a flow rate of up to 100 microL/min and an injection volume of up to 10 microL.

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Research paper thumbnail of Efficiency of short, small-diameter columns for reversed-phase liquid chromatography under practical operating conditions

Journal of chromatography. A, Jan 27, 2015

Prototype small-size (1.0mm I.D., 5cm long) columns for reversed-phase HPLC were evaluated in rel... more Prototype small-size (1.0mm I.D., 5cm long) columns for reversed-phase HPLC were evaluated in relation to instrument requirements. The performance of three types of columns, monolithic silica and particulate silica (2μm, totally porous and 2.6μm, core-shell particles) was studied in the presence of considerable or minimal extra-column effects, while the detector contribution to band broadening was minimized by employing a small size UV-detector cell (6- or 90nL). A micro-LC instrument having small system volume (<1μL) provided extra-column band variance of only 0.01-0.02μL(2). The three columns generated about 8500 theoretical plates for solutes with retention factor, k>1-3 (depending on the column), in acetonitrile/water mobile phase (65/35=vol/vol) at 0.05mL/min, with the instrument specified above. The column efficiency was lower by up to 30% than that observed with a 2.1mm I.D. commercial column. The small-size columns also provided 8000-8500 theoretical plates for well re...

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Research paper thumbnail of Structure Design of Double-Pore Silica and Its Application to HPLC

J Sol Gel Sci Technol, 1998

ABSTRACT

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Research paper thumbnail of Monolithic silica capillary column as a new tool for extraction of methamphetamine in urine

We have established a simple screening method for methamphetamine (MA) in urine using a monolithi... more We have established a simple screening method for methamphetamine (MA) in urine using a monolithic silica capillary column for extraction and using the Simon's reagent for colorimetric determination. Urine was mixed with borate buffer solution (50 mM, pH 10.2) and the mixture was passed through the column connected with the needle of a gas-tight syringe. MA in urine was adsorbed to the column, then eluted with 10 µl of ethyl acetate, and directly spotted on a thin-layer chromatographic plate by dividing the eluate into several aliquots. To separate MA from urine impurities and detect it clearly, a 2-µl volume of a solvent mixture (chloroform : methanol = 95 : 5, v/v, saturated with 28-0x1.fa060bfff8bbp+0mmonium hydroxide) was applied to the spot for concentrically development of the analyte. After drying the solvent, 0.5% sodium nitroprusside solution containing 10% sodium carbonate was sprayed on the plate. The plate was put in a bottle saturated with acetaldehyde, and the ring...

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Research paper thumbnail of A New Monolithic-Type HPLC Column For Fast Separations

Journal of High Resolution Chromatography, 2000

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Research paper thumbnail of SilicaROD™ — A new challenge in fast high-performance liquid chromatography separations

TrAC Trends in Analytical Chemistry, 1998

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Research paper thumbnail of Size Exclusion Chromatography of Standard Polystyrenes with a Wide Range of Molecular Weight Up to 7.45×106 on Monolithic Silica Capillary Columns

Polymer Journal, 2006

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Research paper thumbnail of Monolithic silica capillary column extraction of methamphetamine and amphetamine in urine coupled with thin-layer chromatographic detection

Forensic Toxicology

A monolithic silica capillary column was first developed in Japan in 2001 as a new tool for bette... more A monolithic silica capillary column was first developed in Japan in 2001 as a new tool for better liquid chromatographic separation. The column is made of C18-bonded monolithic silica packed into a capillary glass tube (0.20 mm i.d.). In this study, we used this column for solid-phase extraction of methamphetamine (MA) and amphetamine (AP) in urine. Chromatographic separation was achieved by thin-layer chromatography (TLC) with double-spray detection of each spot. For extraction of amphetamines in urine, samples were mixed with phosphate buffer (pH 3.0, containing 20mM sodium octanesulfate), and the analytes were adsorbed to the column by passing the mixture through it. They were then eluted with a 10-μl volume of ethyl acetate and directly spotted onto a TLC plate. After development, the detection of MA was performed with Simon’s reagent. The plate was air-dried, and then over-sprayed with fluorescamine reagent for detection of AP. A fluorescent spot of AP was observed at 365 nm u...

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Research paper thumbnail of Monolithic silica columns with various skeleton sizes and through-pore sizes for capillary liquid chromatography

Journal of Chromatography A, 2002

Reduction of through-pore size and skeleton size of a monolithic silica column was attempted to p... more Reduction of through-pore size and skeleton size of a monolithic silica column was attempted to provide high separation efficiency in a short time. Monolithic silica columns were prepared to have various sizes of skeletons (approximately 1-2 microm) and through-pores (approximately 2-8 microm) in a fused-silica capillary (50-200 microm I.D.). The columns were evaluated in HPLC after derivatization to C18 phase. It was possible to prepare monolithic silica structures in capillaries of up to 200 microm I.D. from a mixture of tetramethoxysilane and methyltrimethoxysilane. As expected, a monolithic silica column with smaller domain size showed higher column efficiency and higher pressure drop. High external porosity (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; 80%) and large through-pores resulted in high permeability (K = 8 x 10(-14) -1.3 x 10(-12) m2) that was 2-30 times higher than that of a column packed with 5-mirom silica particles. The monolithic silica columns prepared in capillaries produced a plate height of about 8-12 microm with an 80% aqueous acetonitrile mobile phase at a linear velocity of 1 mm/s. Separation impedance, E, was found to be as low as 100 under optimum conditions, a value about an order of magnitude lower than reported for conventional columns packed with 5-microm particles. Although a column with smaller domain size generally resulted in higher separation impedance and the lower total performance, the monolithic silica columns showed performance beyond the limit of conventional particle-packed columns under pressure-driven conditions.

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Research paper thumbnail of Oxynitride glass and fibers thereof

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Research paper thumbnail of Effect of polyethylene glycol on pore structure and separation efficiency of silica-based monolithic capillary columns

Journal of chromatography. A, Jan 15, 2016

Monolithic silica materials (first unclad monolith rods, then monolithic capillary columns) were ... more Monolithic silica materials (first unclad monolith rods, then monolithic capillary columns) were prepared using various amounts of polyethylene glycols (PEGs) with different molecular weight (MW). The monolith rods were used to examine the mesoporosity by argon physisorption technique, and the macroporosity by mercury intrusion porosimetry. Subsequently, silica-based monolithic capillary columns with an inner diameter of 100 μm were produced using the same preparation conditions as used for the rods. The results obtained with the monolith rods showed the following important findings: (1) it is feasible to fabricate monolithic silica rods possessing macropore size of 0.5-1.4 μm by tuning the amount of PEGs (independently of the MW), whereas the macropore volume and the mesoporosity remain similar. (2) the smallest macropore size (0.5 μm) rod prepared with PEG having a MW=20,000g/mol provided a narrower macropore size distribution than with PEG with MW=10,000g/mol. The monolithic capi...

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Research paper thumbnail of Novel Method for DNA Isolation Using High-throughput Monolithic Silica Gel Column in Combination with Anti-chaotropic Effect

Chemistry Letters, Dec 5, 2006

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Research paper thumbnail of Channel Unit for Liquid Chromatograph

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Research paper thumbnail of Oxynitride glass and the fiber thereof

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Research paper thumbnail of Adsorption Column for Purifying Body Fluid

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Nueva columna de tipo monolítico para separaciones rápidas en HPLC

Industria Farmaceutica Equipos Procesos Y Tecnologia, 2000

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Research paper thumbnail of Immobilization of peptide-containing compounds on metal hydroxide gels

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Chromatographic Properties of Miniaturized Silica Rod Columns

Journal of High Resolution Chromatography, 1998

ABSTRACT

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Research paper thumbnail of Monolithic Silica Columns for HPLC, Micro-HPLC, and CEC

Journal of High Resolution Chromatography, 2000

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Research paper thumbnail of Three Dimensional Structure and Liquid Transport Behavior of Siloxane Gels with Co-continuous Macropores

MRS Proceedings, 2004

... Gels with Co-continuous Macropores Haruko Saito 1 , Kazuki Nakanishi 1 , Kazuyuki Hirao 1 , H... more ... Gels with Co-continuous Macropores Haruko Saito 1 , Kazuki Nakanishi 1 , Kazuyuki Hirao 1 , Hiroshi Jinnai 2 , Kei Morisato 3 , Hiroyoshi Minakuchi 3 ... Sci. 27 (2004) 887. [12] Y. Nishikawa, H. Jinnai, T. Koga, T. Hashimoto, ST Hyde, Langmuir 14 (1998) 1242. ...

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Research paper thumbnail of Short communication performance of octadecylsilylated monolithic silica capillary columns of 530 microm inner diameter in HPLC

Journal of Separation Science, Dec 1, 2006

Monolithic silica capillary columns were successfully prepared in a fused silica capillary of 530... more Monolithic silica capillary columns were successfully prepared in a fused silica capillary of 530 microm inner diameter and evaluated in HPLC after octadecylsilylation (ODS). Their efficiency and permeability were compared with those of columns pakked with 5-microm and 3-microm ODS-silica particles. The monolithic silica columns having different domain sizes (combined size of through-pore and skeleton) showed 2.5-4.0-times higher permeability (K= 5.2-8.4 x 10(-14) m2) than capillary columns packed with 3-mm particles, while giving similar column efficiency. The monolithic silica capillary columns gave a plate height of about 11-13 microm, or 11 200-13 400 theoretical plates/150 mm column length, in 80% methanol at a linear mobile phase velocity of 1.0 mm/s. The monolithic column having a smaller domain size showed higher column efficiency and higher pressure drop, although the monolithic column with a larger domain size showed better overall column performance, or smaller separation impedance (E value). The larger-diameter (530 microm id) monolithic silica capillary column afforded a good peak shape in gradient elution of proteins at a flow rate of up to 100 microL/min and an injection volume of up to 10 microL.

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Research paper thumbnail of Efficiency of short, small-diameter columns for reversed-phase liquid chromatography under practical operating conditions

Journal of chromatography. A, Jan 27, 2015

Prototype small-size (1.0mm I.D., 5cm long) columns for reversed-phase HPLC were evaluated in rel... more Prototype small-size (1.0mm I.D., 5cm long) columns for reversed-phase HPLC were evaluated in relation to instrument requirements. The performance of three types of columns, monolithic silica and particulate silica (2μm, totally porous and 2.6μm, core-shell particles) was studied in the presence of considerable or minimal extra-column effects, while the detector contribution to band broadening was minimized by employing a small size UV-detector cell (6- or 90nL). A micro-LC instrument having small system volume (<1μL) provided extra-column band variance of only 0.01-0.02μL(2). The three columns generated about 8500 theoretical plates for solutes with retention factor, k>1-3 (depending on the column), in acetonitrile/water mobile phase (65/35=vol/vol) at 0.05mL/min, with the instrument specified above. The column efficiency was lower by up to 30% than that observed with a 2.1mm I.D. commercial column. The small-size columns also provided 8000-8500 theoretical plates for well re...

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Research paper thumbnail of Structure Design of Double-Pore Silica and Its Application to HPLC

J Sol Gel Sci Technol, 1998

ABSTRACT

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Monolithic silica capillary column as a new tool for extraction of methamphetamine in urine

We have established a simple screening method for methamphetamine (MA) in urine using a monolithi... more We have established a simple screening method for methamphetamine (MA) in urine using a monolithic silica capillary column for extraction and using the Simon's reagent for colorimetric determination. Urine was mixed with borate buffer solution (50 mM, pH 10.2) and the mixture was passed through the column connected with the needle of a gas-tight syringe. MA in urine was adsorbed to the column, then eluted with 10 µl of ethyl acetate, and directly spotted on a thin-layer chromatographic plate by dividing the eluate into several aliquots. To separate MA from urine impurities and detect it clearly, a 2-µl volume of a solvent mixture (chloroform : methanol = 95 : 5, v/v, saturated with 28-0x1.fa060bfff8bbp+0mmonium hydroxide) was applied to the spot for concentrically development of the analyte. After drying the solvent, 0.5% sodium nitroprusside solution containing 10% sodium carbonate was sprayed on the plate. The plate was put in a bottle saturated with acetaldehyde, and the ring...

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Research paper thumbnail of A New Monolithic-Type HPLC Column For Fast Separations

Journal of High Resolution Chromatography, 2000

Bookmarks Related papers MentionsView impact

Research paper thumbnail of SilicaROD™ — A new challenge in fast high-performance liquid chromatography separations

TrAC Trends in Analytical Chemistry, 1998

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Research paper thumbnail of Size Exclusion Chromatography of Standard Polystyrenes with a Wide Range of Molecular Weight Up to 7.45×106 on Monolithic Silica Capillary Columns

Polymer Journal, 2006

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