Minami-rinkan, Japan
Minami-rinkan, Japan

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Koga R.,Kyushu University | Miyoshi Y.,Kyushu University | Negishi E.,Shiseido Irica Technology Inc. | Kaneko T.,Shiseido Co. | And 3 more authors.
Journal of Chromatography A | Year: 2012

A validated and fully automated chiral 2D-HPLC system was developed for the simultaneous determination of N-methyl- d-aspartic acid (NMDA) analogues by combining a long microbore-monolithic ODS column (0.53. mm i.d. × 1000 mm) and narrowbore-enantioselective columns (1.5 mm i.d. × 150 or 250 mm). The target analytes, enantiomers of N-methylaspartic acid (NMA) and N-methylglutamic acid (NMG), were precolumn-derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) and detected by their fluorescence. The values of the lower limit of quantification for these enantiomers were 2.5. fmol. In the tissues and plasma of rats, neither NMA nor NMG were detected. On the other hand, in the mantle and foot of Scapharca broughtonii, a large amount of NMDA was present (170.1 and 43.5. nmol/g), and the enantiomers of NMG were also observed. Meretrix lusoria contained NMDA (29.3. nmol/g) and NMLG (13.8. nmol/g), and Ruditapes philippinarum contained only NMLG (2.6. nmol/g). The obtained results were confirmed using three different enantioselective columns and also using a 2D-HPLC-MS/MS system. These results indicated that neuroactive d-amino acid, NMDA, and its analogues were present in animals, and their physiological significance is expected to be clarified. © 2012 Elsevier B.V.

Oyama T.,Kyushu University | Negishi E.,Shiseido Irica Technology Inc. | Onigahara H.,Kyushu University | Kusano N.,Kyushu University | And 7 more authors.
Journal of Pharmaceutical and Biomedical Analysis | Year: 2015

A new pre-column derivatization reagent with a 6-methoxy-4-quinolone (6-MOQ) moiety for amino acid analysis, 2,5-dioxopyrrolidin-1-yl(2-(6-methoxy-4-oxoquinolin-1(4H)-yl)ethyl) carbonate (6-MOQ-EtOCOOSu), was designed and synthesized. 6-MOQ is a thermo/photostable fluorophore with a high proton-affinity site and sensitive determination could be carried out by a fluorescence detector and also by an electrospray ionization mass spectrometer. Derivatization of amino acids with 6-MOQ-EtOCOOSu was completed within 1. min under mild basic conditions at room temperature. The 6-MOQ derivatives of all chiral proteinogenic amino acids were separated using the combination of three enantioselective columns, Chiralpak QN-AX, Chiralpak ZXIX(+), and KSAACSP-001S, with separation factors of higher than 1.07. The present reagent enables the sensitive determination of amino acid enantiomers, and the values of LLOD using a chiral-HPLC-MS/MS system were 0.05-50. fmol/injection. © 2015 Elsevier B.V.

Kondo T.,Tokyo University of Science | Kobayashi M.,Tokyo University of Science | Saito T.,Tokyo University of Science | Kadota Y.,Shiseido Irica Technology Inc. | And 4 more authors.
Diamond and Related Materials | Year: 2014

Micrometer-sized porous diamond spherical particles (PDSPs) were fabricated from nanodiamond (ND) particles using spray drying and microwave plasma-assisted chemical vapor deposition (MPCVD). Nitrogen gas sorption measurement revealed that the PDSP fabricated from 5 nm detonation ND particles had a Brunauer-Emmett-Teller (BET) surface area of ca. 300 m2 g - 1 and a narrow pore diameter distribution around 10 nm. Nitrogen sorption analysis of PDSP fabricated from various ND particle sizes (diameters from 20 to 50 nm) showed that the BET surface area decreased (200-85 m 2 g- 1) and the average pore diameter increased (4.6-9.3 nm) as the ND diameter increased from 20 to 50 nm. Calculation with a simple model revealed that the pores of the PDSP were derived from the interparticle space of the NDs. The PDSP was durable to immersion in aqueous solutions of HF and NaOH, which indicates the extremely high chemical stability of the diamond-based mesoporous material. The PDSP surface was modified with octadecyl groups using a photochemical method. A column packed with the modified PDSP was successfully employed in a reverse phase high performance liquid chromatography (HPLC) column, and the successful separation of organic compounds was demonstrated with a water/acetonitrile mixture mobile phase. © 2014 Elsevier B.V. All rights reserved.

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