The Experts below are selected from a list of 3591 Experts worldwide ranked by ideXlab platform

Toshimasa Toyooka - One of the best experts on this subject based on the ideXlab platform.

  • rapid Enantiomeric Separation and simultaneous determination of phenethylamines by ultra high performance liquid chromatography with fluorescence and mass spectrometric detection application to the analysis of illicit drugs distributed in the japanese market and biological samples
    Drug Testing and Analysis, 2012
    Co-Authors: Shinsuke Inagaki, Tatsuya Higashi, Haruo Hirashima, Sayuri Taniguchi, Jun Zhe Min, Ruri Kikurahanajiri, Yukihiro Goda, Toshimasa Toyooka
    Abstract:

    A rapid Enantiomeric Separation and simultaneous determination method based on ultra high performance liquid chromatography (UHPLC) was developed for phenethylamine-type abused drugs using (R)-(−)-4-(N,N-dimethylaminosulfonyl)-7-(3-isothiocyanatopyrrolidin-1-yl)-2,1,3-benzoxadiazole ((R)-(−)-DBD-Py-NCS) as the chiral fluorescent derivatization reagent. The derivatives were rapidly Enantiomerically separated by reversed-phase UHPLC using a column of 2.3-µm octadecylsilica (ODS) particles by isocratic elution with water–methanol or water–acetonitrile systems as the mobile phase. The proposed method was applied to the analysis of products containing illicit drugs distributed in the Japanese market. Among the products, 1-(3,4-methylenedioxyphenyl)butan-2-amine (BDB) and 1-(2-methoxy4,5-methylenedioxyphenyl)propan-2-amine (MMDA-2) were detected in racemic form. Furthermore, the method was successfully applied to the analysis of hair specimens from rats that were continuously dosed with diphenyl(pyrrolidin-2-yl)methanol (D2PM). Using UHPLC-fluorescence (FL) detection, (R)- and (S)-D2PM from hair specimens were Enantiomerically separated and detected with high sensitivity. The detection limits of (R)- and (S)-D2PM were 0.12 and 0.21 ng/mg hair, respectively (signal-to-noise ratio (S/N) = 3). Copyright © 2012 John Wiley & Sons, Ltd.

  • derivatization of chiral carboxylic acids with s anabasine for increasing detectability and Enantiomeric Separation in lc esi ms ms
    Journal of Separation Science, 2012
    Co-Authors: Tatsuya Higashi, Takeshi Fukushima, Shoujiro Ogawa, Hiroaki Tadokoro, Megumi Kawasaki, Haruhito Tsutsui, Toshimasa Toyooka
    Abstract:

    A simple and practical derivatization procedure for increasing the detectability and Enantiomeric Separation of chiral carboxylic acids in LC/ESI-MS/MS has been developed. (S)-Anabasine (ANA) was used as the derivatization reagent and rapidly reacted with carboxylic acids [3-hydroxypalmitic acid (3-OH-PA), 2-(β-carboxyethyl)-6-hydroxy-2,7,8-trimethylchroman (γ-CEHC), and etodolac] in the presence of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholium chloride. The resulting ANA-derivatives were highly responsive in ESI-MS operating in the positive-ion mode and gave characteristic product ions during MS/MS, which enabled sensitive detection using selected reaction monitoring; the detection responses of the ANA-derivatives were increased by 20-160-fold over those of the intact carboxylic acids and the limits of detection were in the low femtomole range (1.8-11 fmol on the column). The ANA-derivatization was also effective for the enatiomeric Separation of the chiral carboxylic acids; the resolution was 1.92, 1.75, and 2.03 for 3-OH-PA, γ-CHEC, and etodolac, respectively. The derivatization procedure was successfully applied to a biological sample analysis; the derivatization followed by LC/ESI-MS/MS enabled the Separation and detection of trace amounts of 3-OH-PA in neonatal dried blood spot and γ-CEHC in human saliva with a simple pretreatment and small sample volume.

  • simultaneous determination of dl lactic acid and dl 3 hydroxybutyric acid enantiomers in saliva of diabetes mellitus patients by high throughput lc esi ms ms
    Analytical and Bioanalytical Chemistry, 2012
    Co-Authors: Haruhito Tsutsui, Jun Zhe Min, Kenichiro Todoroki, Toshiki Mochizuki, Toshio Maeda, Ichiro Noge, Yutaka Kitagawa, Koichi Inoue, Toshimasa Toyooka
    Abstract:

    A simultaneous determination method for the enantiomers of chiral carboxylic acids by the combination of ultraperformance liquid chromatography and mass spectrometry (UPLC–MS/MS) has been developed. (S)(+)-1-(2-Pyrrolidinylmethyl)-pyrrolidine (S-PMP) was used as the derivatization reagent for the high-throughput determination of biological chiral carboxylic acids, i.e., lactic acid (LA) and 3-hydroxybutyric acid (HA). The S-PMP efficiently reacted with the carboxylic acids under mild conditions at room temperature in the presence of 2,2′-dipyridyl disulfide and triphenylphosphine. The resulting S-PMP derivatives were highly responsive in the electrospray ionization (ESI)-MS operating in the positive-ion mode and gave characteristic product ions during the MS/MS, which enabled the sensitive detection using selected reaction monitoring. The derivatization was effective for the Enantiomeric Separation of the chiral carboxylic acids, and the resolution values of dl-LA and dl-HA were 4.91 and 9.37, respectively. Furthermore, a rapid Separation of the derivatives of dl-LA and dl-HA within 7 min was performed using the UPLC system. The limits of detection on the column were in the low femtogram range (5–12 fg). The proposed procedure was successfully applied for the determination of the d- and l-isomers of LA and HA in the saliva of diabetes mellitus (DM) patients and healthy volunteers. The d-LA in DM patients was clearly higher than that in normal subjects. The derivatization followed by UPLC–ESI-MS/MS enabled the Enantiomeric Separation and detection of trace amounts of LA and HA in human saliva with a simple pretreatment and small sample volume.

Salvatore Fanali - One of the best experts on this subject based on the ideXlab platform.

  • Enantiomeric Separation of new cathinone derivatives designer drugs by capillary electrochromatography using a chiral stationary phase based on amylose tris 5 chloro 2 methylphenylcarbamate
    Electrophoresis, 2014
    Co-Authors: Z Aturki, Martin G Schmid, Bezhan Chankvetadze, Salvatore Fanali
    Abstract:

    In this study, a chiral CEC method for the Enantiomeric Separation of ten cathinone derivatives, by means of a polysaccharide-based chiral stationary phase, has been developed. Capillary columns of 100 μm id packed with amylose tris(5-chloro-2-methylphenylcarbamate) coated on silica, also called Sepapak 3 or Lux Amylose-2, were used to achieve the enantioSeparation of the studied designer drugs. Enantioresolution, chromatographic retention, and Separation efficiency were evaluated in dependence of mobile-phase composition in terms of the content of the organic modifier, nature, and pH buffer. To obtain a sensitivity improvement, a field-amplified sample injection was evaluated optimizing the sample solvent composition and injection time. The LODs and LOQs values were in the range 25-100 and 50-150 ng/mL, respectively, for all the racemic compounds. Good results in terms of resolution (Rs ), Separation efficiency (N/m), and short analysis times were obtained using a mixture of ACN/methanol/sodium acetate pH 9 (89/10/1, v/v/v). Applying a voltage of 10 kV and a temperature of 20°C, the analyzed cathinone derivatives were separated in their enantiomers in less than 10 min. A study, concerning the method precision, in terms of intra- and interday repeatability and column-to-column reproducibility was carried out in accordance with the analytical procedures for method validation. Intra- and interday repeatability provided RSD values in the ranges 1.1-1.7, 1.3-2.3% for retention time and 1.3-2.6, 2.1-3.4% for peak area, respectively.

  • Enantiomeric Separation of some demethylated analogues of clofibric acid by capillary zone electrophoresis and nano liquid chromatography
    Electrophoresis, 2006
    Co-Authors: Marialuigia Fantacuzzi, Giancarlo Bettoni, Giovanni Dorazio, Salvatore Fanali
    Abstract:

    The Enantiomeric Separation of some demethylated analogues of clofibric acid, namely 2-(6-chloro-benzothiazol-2-ylsulfanyl)-, 2-(6-methoxy-benzothiazol-2-ylsulfanyl)-, 2-(quinolin-2-yloxy)-, 2-(6-chloro-quinolin-2-yloxy)-, 2-(7-chloro-quinolin-4-yloxy)-propionic acid (compounds A-E, respectively), has been studied by CZE and nano-LC using for the first technique two beta-CD derivatives and vancomycin added to the BGE and vancomycin-modified silica particles for the second one, with the aim to find the optimum experimental conditions for the baseline resolution. The type and the concentration of the chiral selector added to the BGE, the buffer pH, the type of organic modifier and its concentration, the capillary temperature and the applied voltage played a very important role in the enantioresolution of the analysed compounds. The use of 6-monodeoxy-6-monoamino-beta-CD allowed to achieve baseline resolution of four of five clofibric acid derivatives in less than 10 min while heptakis-(2,3,6-tri-O-methyl)-beta-CD partially resolved the same compounds in their enantiomers. Employing vancomycin as the chiral selector in CZE, the counter-current partial filling method was chosen achieving baseline resolution of four analytes. All the studied compounds were enantioresolved employing a capillary column packed with vancomycin stationary phase by nano-LC, and the resolution was strongly influenced by the concentration of the organic modifier and by the pH of the mobile phase. The best results were achieved at pH 4.5 in presence of 60% of methanol (MeOH). However, longer analysis times were observed in the experiments carried out by nano-LC.

  • Enantiomeric Separation of acidic compounds of pharmaceutical interest by capillary electrochromatography employing glycopeptide antibiotic stationary phases
    Journal of Chromatography A, 2003
    Co-Authors: Salvatore Fanali, Paolo Catarcini, Carla Presutti
    Abstract:

    Abstract Enantiomeric Separation of some selected acidic compounds of pharmaceutical interest belonging to the group of non-steroidal anti-inflammatory drugs were separated by capillary electrochromatography employing silica based glycopeptide antibiotic stationary phases, namely vancomycin or a teicoplanin derivatives (Hepta-Tyr). The vancomycin stationary phase allowed to achieve the chiral resolution of some racemic studied compounds only using mobile phases containing ammonium formate at a relatively low pH 2.5–3.5 and acetonitrile. Employing the teicoplanin derivative stationary phase, good Enantiomeric resolution was achieved eluting with mobile phases containing sodium phosphate pH 6–acetonitrile. Enantiomers were moved to the detector because a relatively high reversed electroosmotic flow (due to the positive charge of the stationary phase) and to the electrophoretic mobility of analytes.

Daniel W. Armstrong - One of the best experts on this subject based on the ideXlab platform.

  • evaluation of the edman degradation product of vancomycin bonded to core shell particles as a new hplc chiral stationary phase
    Chirality, 2018
    Co-Authors: Garrett Hellinghausen, Diego A Lopez, Jauh Tzuoh Lee, Yadi Wang, Choyce A Weatherly, Abiud Portillo, Alain Berthod, Daniel W. Armstrong
    Abstract:

    A modified macrocyclic glycopeptide-based chiral stationary phase (CSP), prepared via Edman degradation of vancomycin, was evaluated as a chiral selector for the first time. Its applicability was compared with other macrocyclic glycopeptide-based CSPs: TeicoShell and VancoShell. In addition, another modified macrocyclic glycopeptide-based CSP, NicoShell, was further examined. Initial evaluation was focused on the complementary behavior with these glycopeptides. A screening procedure was used based on previous work for the Enantiomeric Separation of 50 chiral compounds including amino acids, pesticides, stimulants, and a variety of pharmaceuticals. Fast and efficient chiral Separations resulted by using superficially porous (core-shell) particle supports. Overall, the vancomycin Edman degradation product (EDP) resembled TeicoShell with high enantioselectivity for acidic compounds in the polar ionic mode. The simultaneous Enantiomeric Separation of 5 racemic profens using liquid chromatography-mass spectrometry with EDP was performed in approximately 3 minutes. Other highlights include simultaneous liquid chromatography Separations of rac-amphetamine and rac-methamphetamine with VancoShell, rac-pseudoephedrine and rac-ephedrine with NicoShell, and rac-dichlorprop and rac-haloxyfop with TeicoShell.

  • Enantiomeric Separations of ruthenium ii polypyridyl complexes using hplc with cyclofructan chiral stationary phases
    Chirality, 2015
    Co-Authors: Yang Shu, Zachary S Breitbach, Milan K Dissanayake, Sirantha Perera, Joseph M Aslan, Nagham Alatrash, Frederick M Macdonnell, Daniel W. Armstrong
    Abstract:

    The Enantiomeric Separation of 21 ruthenium (II) polypyridyl complexes was achieved with a novel class of cyclofructan-based chiral stationary phases (CSPs) in the polar organic mode. Aromatic derivatives on the chiral selectors proved to be essential for enantioselectivity. The R-napthylethyl carbamate functionalized cyclofructan 6 (LARIHC CF6-RN) column proved to be the most effective overall, while the dimethylphenyl carbamate cyclofructan 7 (LARIHC CF7-DMP) showed complementary selectivity. A combination of acid and base additives was necessary for optimal Separations. The retention factor vs. acetonitrile/methanol ratio plot showed a U-shaped retention curve, indicating that different interactions take place at different polar organic solvent compositions. The Separation results indicated that π-π interactions, steric effects, and hydrogen bonding contribute to the Enantiomeric Separation of ruthenium (II) polypyridyl complexes with cyclofructan chiral stationary phases in the polar organic mode.

  • Separation of enantiomers and control of elution order of β lactams by gc using cyclodextrin based chiral stationary phases
    Chromatographia, 2009
    Co-Authors: Ke Huang, Daniel W. Armstrong, Eniko Forro, Ferenc Fulop, Antal Peter
    Abstract:

    Enantiomers of 19 racemic β-lactams, with 3 and 4-position substitutions, were separated using gas chromatography. Excellent results were achieved on derivatized cyclodextrin-based GC chiral stationary phases (CSPs). All 19 compounds were baseline separated, most with high resolution factors. The Chiraldex G-TA was found to be the most powerful CSP with the broadest enantioselectivity, while Chiraldex B-DM produced the fastest Separations for most of the compounds assayed. Results obtained in this work suggest that GC can serve as a potential method for the Enantiomeric Separation of sufficiently volatile solid β-lactams.

  • Enantiomeric Separation of Isochromene Derivatives by Cyclodextrin-Modified Micellar Capillary Electrophoresis
    Journal of Liquid Chromatography & Related Technologies, 2008
    Co-Authors: Nicola Della Ca, Richard C Larock, Daniel W. Armstrong
    Abstract:

    Abstract The Enantiomeric Separations of highly hydrophobic isochromene derivatives were performed and optimized using cyclodextrin-modified micellar capillary electrophoresis. Hydroxypropyl-γ-cyclodextrin proved to be the most effective chiral selector for the enantioSeparation of these analytes. The effects of cyclodextrin and sodium dodecyl sulfate concentration and organic modifier were examined in order to optimize the Separation conditions. Addition of an organic solvent modifier to the run buffer served to increase the analyte' solubility and enhance the Separation efficiency. A highly acidic pH was necessary to effectively suppress the electroosmotic flow when operating in the reverse polarity mode.

Marianne Fillet - One of the best experts on this subject based on the ideXlab platform.

  • Enantiomeric Separation of acidic compounds using single isomer amino cyclodextrin derivatives in nonaqueous capillary electrophoresis
    Electrophoresis, 2006
    Co-Authors: Ines Fradi, Annecatherine Servais, Matteo Pedrini, Patrice Chiap, Robert Ivanyi, Jacques Crommen, Marianne Fillet
    Abstract:

    The Enantiomeric Separation of a series of acidic pharmaceuticals (mostly nonsteroidal anti-inflammatory drugs) has been investigated in NACE systems using single-isomer amino beta-CD derivatives. The first part of this study consisted of the selection of the basic experimental conditions to separate efficiently the enantiomers of acidic drugs. Several parameters, such as the nature of the ionic BGE components, were studied and a methanolic solution of ammonium acetate containing the cationic CD was selected as BGE. A D-optimal design with 20 experimental points was then applied and the nature and concentration of the CD were found to have a significant effect on the Enantiomeric resolution for all studied compounds. Resolution (R(s)) values were always higher with 6-monodeoxy-6-mono(3-hydroxy)propylamino-beta-CD (PA-beta-CD) compared to those obtained with 6-monodeoxy-6-mono(2-hydroxy)propylamino-beta-CD (IPA-beta-CD). However, the latter led to shorter migration times. Generic NACE conditions were then selected by means of the multivariate approach in order to obtain the highest R(s) values in a minimum amount of time. Finally, dependence of Separation selectivity, resolution, as well as mobility difference on chiral selector concentration was discussed and binding constants with PA-beta-CD were estimated for the two enantiomers of one of the model compounds, suprofen in these NACE systems.

  • Enantiomeric Separation of basic compounds using heptakis 2 3 di o methyl 6 o sulfo β cyclodextrin in combination with potassium camphorsulfonate in nonaqueous capillary electrophoresis optimization by means of an experimental design
    Electrophoresis, 2004
    Co-Authors: Annecatherine Servais, Patrice Chiap, Marianne Fillet, Walthere Dewe, Philippe Hubert, Jacques Crommen
    Abstract:

    The Enantiomeric Separation of a series of basic pharmaceuticals (beta-blockers, local anesthetics, sympathomimetics) has been investigated in nonaqueous capillary electrophoresis (NACE) systems using heptakis(2,3-di-O-methyl-6-O-sulfo)-beta-cyclodextrin (HDMS-beta-CD) in combination with potassium camphorsulfonate (camphorSO3-). For this purpose, a face-centered central composite design with 11 experimental points was applied. The effect of the concentrations of HDMS-beta-CD and camphorSO3- on enantioresolution was statistically evaluated and depended largely on the considered analyte. The presence of camphorSO3- was found to be particularly useful for the enantioSeparation of compounds with high affinity for the anionic CD. CamphorSO3- seems to act as a competitor, reducing the affinity for the CD, probably by ion-pair formation with these analytes. For compounds with lower affinity for HDMS-beta-CD, the combination of camphorSO3- and the CD appeared to have a favorable effect on enantioresolution only if the optimal CD concentration could be reached. On the other hand, for compounds characterized by a very low affinity for the anionic CD, the association of camphorSO3- and HDMS-beta-CD is always unfavorable. Finally, experimental conditions were selected by means of the multivariate approach in order to obtain the highest resolution (Rs) value for each studied compound.

Haruhito Tsutsui - One of the best experts on this subject based on the ideXlab platform.

  • derivatization of chiral carboxylic acids with s anabasine for increasing detectability and Enantiomeric Separation in lc esi ms ms
    Journal of Separation Science, 2012
    Co-Authors: Tatsuya Higashi, Takeshi Fukushima, Shoujiro Ogawa, Hiroaki Tadokoro, Megumi Kawasaki, Haruhito Tsutsui, Toshimasa Toyooka
    Abstract:

    A simple and practical derivatization procedure for increasing the detectability and Enantiomeric Separation of chiral carboxylic acids in LC/ESI-MS/MS has been developed. (S)-Anabasine (ANA) was used as the derivatization reagent and rapidly reacted with carboxylic acids [3-hydroxypalmitic acid (3-OH-PA), 2-(β-carboxyethyl)-6-hydroxy-2,7,8-trimethylchroman (γ-CEHC), and etodolac] in the presence of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholium chloride. The resulting ANA-derivatives were highly responsive in ESI-MS operating in the positive-ion mode and gave characteristic product ions during MS/MS, which enabled sensitive detection using selected reaction monitoring; the detection responses of the ANA-derivatives were increased by 20-160-fold over those of the intact carboxylic acids and the limits of detection were in the low femtomole range (1.8-11 fmol on the column). The ANA-derivatization was also effective for the enatiomeric Separation of the chiral carboxylic acids; the resolution was 1.92, 1.75, and 2.03 for 3-OH-PA, γ-CHEC, and etodolac, respectively. The derivatization procedure was successfully applied to a biological sample analysis; the derivatization followed by LC/ESI-MS/MS enabled the Separation and detection of trace amounts of 3-OH-PA in neonatal dried blood spot and γ-CEHC in human saliva with a simple pretreatment and small sample volume.

  • simultaneous determination of dl lactic acid and dl 3 hydroxybutyric acid enantiomers in saliva of diabetes mellitus patients by high throughput lc esi ms ms
    Analytical and Bioanalytical Chemistry, 2012
    Co-Authors: Haruhito Tsutsui, Jun Zhe Min, Kenichiro Todoroki, Toshiki Mochizuki, Toshio Maeda, Ichiro Noge, Yutaka Kitagawa, Koichi Inoue, Toshimasa Toyooka
    Abstract:

    A simultaneous determination method for the enantiomers of chiral carboxylic acids by the combination of ultraperformance liquid chromatography and mass spectrometry (UPLC–MS/MS) has been developed. (S)(+)-1-(2-Pyrrolidinylmethyl)-pyrrolidine (S-PMP) was used as the derivatization reagent for the high-throughput determination of biological chiral carboxylic acids, i.e., lactic acid (LA) and 3-hydroxybutyric acid (HA). The S-PMP efficiently reacted with the carboxylic acids under mild conditions at room temperature in the presence of 2,2′-dipyridyl disulfide and triphenylphosphine. The resulting S-PMP derivatives were highly responsive in the electrospray ionization (ESI)-MS operating in the positive-ion mode and gave characteristic product ions during the MS/MS, which enabled the sensitive detection using selected reaction monitoring. The derivatization was effective for the Enantiomeric Separation of the chiral carboxylic acids, and the resolution values of dl-LA and dl-HA were 4.91 and 9.37, respectively. Furthermore, a rapid Separation of the derivatives of dl-LA and dl-HA within 7 min was performed using the UPLC system. The limits of detection on the column were in the low femtogram range (5–12 fg). The proposed procedure was successfully applied for the determination of the d- and l-isomers of LA and HA in the saliva of diabetes mellitus (DM) patients and healthy volunteers. The d-LA in DM patients was clearly higher than that in normal subjects. The derivatization followed by UPLC–ESI-MS/MS enabled the Enantiomeric Separation and detection of trace amounts of LA and HA in human saliva with a simple pretreatment and small sample volume.

  • Chiral amines as reagents for HPLC-MS enantioSeparation of chiral carboxylic acids.
    IEEE Journal of Solid-state Circuits, 2012
    Co-Authors: Haruhito Tsutsui, Jun Zhe Min, Shinya Fujii, Tasuku Sakamoto, Kenichiro Todoroki, Toshimasa Toyo'oka
    Abstract:

    Mass spectrometry (MS) has become a popular analytical technique because of its high sensitivity and specificity. Therefore, the use of a chiral derivatization reagent for the MS detection seems to be efficient for the Enantiomeric Separation of racemates. However, the number of chiral reagents for the liquid chromatography (LC)-tandem mass spectrometry (MS/MS) analysis is very limited. The applicability of commercially available chiral amines as the derivatization reagents for the Enantiomeric Separation of chiral carboxylic acids is reported in this paper by using non-steroidal anti-inflammatory drugs (NSAIDs), i.e. ibuprofen, flurbiprofen, and loxoprofen. The efficiency of the chiral reagents was evaluated in terms of tagging easiness, Separation by reversed-phase chromatography, and detection sensitivity by electrospray ionization (ESI)-MS/MS. Among the tested eight chiral amines, i.e. (R)-(+)-4-(3-aminopyrrolidin-1-yl)-7-(N,N-dimethylaminosulfonyl)-2,1,3-benzoxadiazole (DBD-APy), (S)-(+)-1-(2-pyrrolidinylmethyl)-pyrrolidine (PMP), L-prolinamide, (3R)-(-)-1-benzyl-3-aminopyrrolidine, (S)-(+)-1-cyclohexyl-ethylamine, (3R)-(+)-3-(trifluoroacetamido)-pyrrolidine (TFAP), (R)-(-)-1-aminoindan (AI), and (S)-(+)-tetrahydrofurfuryl-amine, DBD-APy, PMP, AI, and TFAP could be used as the chiral reagents for the Enantiomeric Separation of the NSAIDs. The Rs values and the detection limits of the derivatives were in the range of 1.29-3.85 and 0.57-0.96 fmol, respectively. These four reagents were applied for the determination of the NSAIDs in rat plasma.