United States
United States

Time filter

Source Type

Gritti F.,University of Tennessee at Knoxville | Tanaka N.,GL Sciences Inc. | Guiochon G.,University of Tennessee at Knoxville
Journal of Chromatography A | Year: 2012

The gradient elution performance of narrow-bore 2.3mm×50mm (N733) and wider bore 3.2mm×50mm (N648 and N655) prototype silica monolithic columns was investigated and compared to the performance of commercially available columns packed with sub-2μm fully porous particles (2.1mm×50mm, 1.7μm BEH-C 18, Waters) and sub-3μm superficially porous particles (2.1mm×50mm, 2.7μm Halo-ES-Peptide-C 18 (AMT), 1.7 and 2.6μm Kinetex-C 18, Phenomenex). Results show that the two wide monolithic columns show peak capacities similar to the one measured for the Kinetex column. In contrast, the narrow-bore monolithic column delivers a lower performance (-30%) than the BEH, the Halo and the Kinetex columns. This work stresses out the importance of reducing the extra-column band broadening contribution of HPLC instruments when short 2.1mm I.D. columns are used. The part of the instrument contribution originating downstream the column is important for all compounds; the one originating upstream the column is significant only for weakly retained compounds. © 2012 Elsevier B.V.

Saito T.,Tokai University | Namera A.,Hiroshima University | Miura N.,Tokai University | Ohta S.,GL Sciences Inc. | And 3 more authors.
Forensic Toxicology | Year: 2013

A 59-year-old man was found dead in his house, where three sachets containing herbal blends were found on a table. The sachet contents were analyzed by gas chromatography-mass spectrometry and found to contain [1-(5-fluoropentyl)-1H-indol-3-yl](4-methyl-1-naphthalenyl)methanone (MAM-2201). The deceased was subjected to forensic autopsy. There were neither external injuries nor endogenous diseases judged by macroscopic and microscopic observations. Liquid chromatography-electrospray ionization-tandem mass spectrometry was used to quantitate the concentrations of MAM-2201 in postmortem samples using deuterated MAM-2201 as internal standard. The MAM-2201 concentrations were: 12.4 ng/ml in whole blood; 18.1 ng/g in the liver; 11.2 ng/g in the kidney; 4.3 ng/g in the brain; and 1,535 ng/g in the adipose tissue. We concluded that the man's death was caused by acute intoxication with MAM-2201. In addition, we propose that the adipose tissue is the specimen of choice to detect MAM-2201 in the unchanged form. To our knowledge, this is the first report of a fatal MAM-2201 poisoning case. In addition, this report is also the first to describe the distribution of the drug in postmortem human tissues and blood. © 2013 Japanese Association of Forensic Toxicology and Springer Japan.

Namera A.,Hiroshima University | Nakamoto A.,Forensic Science Laboratory | Saito T.,Tokai University | Miyazaki S.,GL Sciences Inc.
Journal of Separation Science | Year: 2011

Monolith was first used as a material for chromatographic separation two decades ago and solid-phase extraction over 10 years, and since then, separation science has undergone a dramatic change owing to advancements in analytical technology. Recently, monolith has been modified to suit various devices for the extraction and enrichment of analytes in any matrices of environmental, food, and biological analyses. This approach has contributed to miniaturization and automation for sample preparation, and it can reduce the time and cost requirements of sample preparation. Recently, numerous applications have been demonstrated for online and inline preconcentration coupled with monolith, and many kinds of devices have been designed and developed for offline devices. In this review, these applications and devices are listed and discussed in reference to other fields. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sakai-Kato K.,Japan National Institute of Health Sciences | Ota S.,GL Sciences Inc. | Takeuchi T.,Gifu University | Kawanishi T.,Japan National Institute of Health Sciences
Journal of Chromatography A | Year: 2011

We developed a method to separate colloidally dispersed nanoparticles on monolithic capillary columns. Silica nanoparticles were eluted according to their sizes, and the plots of the logarithm of the size of nanoparticles against their elution volume showed good linearity (r= 0.992) over wide range of sizes. Because of the high porosity of the monolithic column (porosity; 88%), the column's length could be increased without clogging of the dispersed samples and the pressure in a long column (500 mm × 0.2 mm i.d.) was low, with a value of 5.8. MPa at a flow rate of 1 μL/min. We demonstrate that this method using monolithic capillary columns could be used as a powerful tool for size separation of nanometer-size materials, which will open a new pathway to quality control of nanomaterials in nanotechnology applications. © 2011 Elsevier B.V.

Ikegami T.,Kyoto Institute of Technology | Tanaka N.,GL Sciences Inc.
Annual Review of Analytical Chemistry | Year: 2016

Monolithic silica columns have greater (through-pore size)-(skeleton size) ratios than particulate columns and fixed support structures in a column for chemical modification, resulting in high-efficiency columns and stationary phases. This review looks at how the size range of monolithic silica columns has been expanded, how high-efficiency monolithic silica columns have been realized, and how various methods of silica surface functionalization, leading to selective stationary phases, have been developed on monolithic silica supports, and provides information on the current status of these columns. Also discussed are the practical aspects of monolithic silica columns, including how their versatility can be improved by the preparation of small-sized structural features (sub-micron) and columns (1 mm ID or smaller) and by optimizing reaction conditions for in situ chemical modification with various restrictions, with an emphasis on recent research results for both topics. Copyright © 2016 by Annual Reviews. All rights reserved.

Kawachi Y.,Kyoto Institute of Technology | Ikegami T.,Kyoto Institute of Technology | Takubo H.,Kyoto Institute of Technology | Ikegami Y.,Okami Chemical Industry | And 3 more authors.
Journal of Chromatography A | Year: 2011

Fourteen commercially available particle-packed columns and a monolithic column for hydrophilic interaction liquid chromatography (HILIC) were characterized in terms of the degree of hydrophilicity, the selectivity for hydrophilic-hydrophobic substituents, the selectivity for the regio and configurational differences in hydrophilic substituents, the selectivity for molecular shapes, the evaluation of electrostatic interactions, and the evaluation of the acidic-basic nature of the stationary phases using nucleoside derivatives, phenyl glucoside derivatives, xanthine derivatives, sodium p-toluenesulfonate, and trimethylphenylammonium chloride as a set of samples. Principal component analysis based on the data of retention factors could separate three clusters of the HILIC phases. The column efficiency and the peak asymmetry factors were also discussed. These data on the selectivity for partial structural differences were summarized as radar-shaped diagrams. This method of column characterization is helpful to classify HILIC stationary phases on the basis of their chromatographic properties, and to choose better columns for targets to be separated. Judging from the retention factor for uridine, these HILIC columns could be separated into two groups: strongly retentive and weakly retentive stationary phases. Among the strongly retentive stationary phases, zwitterionic and amide functionalities were found to be the most selective on the basis of partial structural differences. The hydroxyethyl-type stationary phase showed the highest retention factor, but with low separation efficiency. Weakly retentive stationary phases generally showed lower selectivity for partial structural differences. © 2011 Elsevier B.V.

Hasegawa G.,Kyoto University | Morisato K.,GL Sciences Inc. | Kanamori K.,Kyoto University | Nakanishi K.,Kyoto University
Journal of Separation Science | Year: 2011

Separation media based on hierarchically porous titania (TiO2) monoliths for highperformance liquid chromatography (HPLC) have been successfully fabricated by the sol-gel process of titanium alkoxide in a mild condition utilizing a chelating agent and mineral salt. The as-gelled TiO 2 monoliths were subjected to a simple solvent exchange process from ethanol (EtOH) to H2O followed by drying and calcination. The resultant monolithic TiO2 columns consist of anatase crystallites with the typical specific surface area of more than 200m2/g. The resultant monolithic TiO2 column calcined at 200 and 400°C exhibited a good separation performance for organophosphates as well as for polar benzene derivatives in the normal-phase mode. © 2011 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim.

Zhu Y.,Kyoto University | Morisato K.,GL Sciences Inc. | Li W.,Zhejiang University | Kanamori K.,Kyoto University | Nakanishi K.,Kyoto University
ACS Applied Materials and Interfaces | Year: 2013

Silver nanoparticles (Ag NPs) have been homogeneously introduced into hierarchically porous monolithic silica columns with well-defined macropores and SBA-15-type hexagonally ordered mesopores by using ethanol as the mild reductant. Within the cylindrical silica mesopores treated with aminopropyl groups as the host, monocrystalline Ag NPs and nanorods are obtained after being treated in silver nitrate/ethanol solution at room temperature for different durations of reducing time. The loading of Ag NPs in the monolith can be increased to 33 wt % by the repetitive treatment, which also led to the formation of polycrystalline Ag nanorods in the mesopores. Although the bare silica column cannot separate aromatic hydrocarbons, good separation of those molecules by noncharged Ag NPs confined in the porous structure of the monolith has been for the first time demonstrated with the Ag NP-embedded silica column. The NP-embedded monolithic silica would be a powerful separation tool for hydrocarbons with different number, position, and configuration of unsaturated bonds. © 2013 American Chemical Society.

Iwasaki M.,Kyoto University | Sugiyama N.,Keio University | Tanaka N.,GL Sciences Inc. | Ishihama Y.,Kyoto University | Ishihama Y.,Keio University
Journal of Chromatography A | Year: 2012

We have developed one-dimensional liquid chromatography-tandem mass spectrometry systems with meter-scale reversed phase monolithic silica-C 18 capillary columns for human proteome analysis. When tryptic peptides from 4μg HeLa cell lysate proteins were directly injected onto a 4-m, 100μm i.d. monolithic silica-C 18 column and an 8-h gradient was applied at 500nL/min, 41,319 non-redundant tryptic peptides from 5,970 proteins were successfully identified from quadruplicate measurements; this is the best result yet reported without the use of exhaustive pre-fractionation. Because separation efficiency in the 4-m long monolithic column system (8-h gradient, 26,805 peptides identified on average) was much higher than that in a 15-cm long, conventional particle-packed column system (65-min gradient, 10,183 peptides identified), ion suppression caused by co-elution of peptides was drastically reduced, resulting in a 5-fold improvement in MS responses on average. However, we did not observe dynamic range extension for the identified human peptides, whereas 78-fold extension was observed in our previous analysis of the Escherichia coli proteome (Anal. Chem., 82 (2010) 2616). This was probably because the current analytical technologies are still not adequate to allow acquisition of MS/MS spectra for detected precursor ions from highly complex human peptide mixtures, even though MS sensitivity was enhanced by the improved separation in this LC system. More efficient LC separation and faster MS/MS scanning are still needed for complete human proteome analysis. © 2011 Elsevier B.V.

Fallas M.M.,University of the West of England | Tanaka N.,GL Sciences Inc. | Buckenmaier S.M.C.,Hewlett - Packard | McCalley D.V.,University of the West of England
Journal of Chromatography A | Year: 2013

The influence of pressure on the retention of several types of solute, including acids, bases and neutrals, was studied by the use of restriction capillaries added to the end of various monomeric and polymeric octadecylsilyl-modified 5. μm particle size columns. Although it appeared that certain polymeric columns could give somewhat greater increases in retention with pressure, differences in behaviour between these different C18 columns were rather small. Differences in solute molecular size were most important in determining increases in retention with pressure. However, solute structure such as polarity and planarity were also influential. A prototype C30 column gave interesting selectivity changes between planar and non-planar solutes as a function of pressure. Considerable selectivity differences with pressure were shown when diverse mixtures of solutes were analysed. For the solutes studied, only minor effects of increased pressure on column efficiency and peak shape were noted. © 2013 Elsevier B.V.

Loading GL Sciences Inc. collaborators
Loading GL Sciences Inc. collaborators