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Quantitative high-throughput determination of endogenous retinoids in human plasma using triple-stage liquid chromatography/tandem mass spectrometry

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RAPID COMMUNICATIONS IN MASS SPECTROMETRY 2007年第7期21卷 1176-1186页

作者： Gundersen, Thomas E. Bastani, Nasser E. Blomhoff, Rune Univ Oslo Inst Basic Med Sci Oslo Norway Vitas As Oslo Innovat Pk N-0349 Oslo Norway

A high-throughput ultrasensitive analytical method based on liquid chromatography with positive ion atmospheric pressure chemical ionization (APCI) coupled to tandem mass spectrometric detection (LC/MS/MS) was developed for the determination of all-trans-4-oxo-retinoic acid (at4oxoRA), 13-cis-4-oxo-retinoic acid (13c4oxoRA), 13-cis-retinoic acid (13cRA), all-trans-retinoic acid (atRA) and all-trans-retinol (atROH) in human plasma. A stable isotope of atRA was used as internal standard (IS). The analytes and IS were isolated from 100 ULL plasma by acetonitrile mono-phase extraction (MPE) performed in black 96-well microtiterplates. A 100 mu L injection was focused on-column and chromatographed on an Agilent ZORBAX SB-C18 rapid-resolution high-throughput (RRHT) column with 1.8-mu m particles (4.6 mm X 50 mm) maintained at 60 degrees C. The initial mobile phase composition was acetonitrile/water/formic acid (10:90:0.1, v/v/v) delivered at 1.8 mL/ min. Elution was accomplished by a fast gradient to acetonitrile/methanol/formic acid (90:10:0.1, v/v/ v). The method had a chromatographic total run time of 7 min. An Applied Biosystems 4000 Q TRAP linear tandem mass spectrometer equipped with a heated nebulizer (APCI) ionization source was operated in multiple reaction monitoring (MRM) mode with the precursor-to-product ion transitions m/z 315.4 -> 297 (4-oxo-retinoic acids), 301.2 -> 205 (retinoic acids), 305.0 -> 209 (IS) and 269.2 -> 93 (retinol) used for quantification. The assay was fully validated and found to have acceptable accuracy, precision, linearity, sensitivity and selectivity. The mean extraction recoveries from spiked plasma samples were 80-105% for the various retinoids at three different levels. The intra-day accuracy of the assay was within 8% of nominal and intra-day precision was better than 8% coefficient of variance (CV) for retinoic acids. Inter-day precision results for quality control samples run over a 12-day period alongside clinical samples showe

关键词： SOLID-PHASE EXTRACTION ALL-TRANS 13-CIS-RETINOIC ACID 9-CIS-RETINOIC ACID 4-OXO METABOLITES array detection SERUM QUANTIFICATION IDENTIFICATION SEPARATION

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A quantum study of multibit phase coding for optical storage

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IEEE JOURNAL OF QUANTUM ELECTRONICS 2006年第9-10期42卷 1001-1007页

作者： Hsu, Magnus T. L. Delaubert, Vincent Bowen, Warwick P. Fabre, Claude Bachor, Hans-A. Lam, Ping Koy Australian Natl Univ Dept Phys Australian Res Council Ctr Excellence Quantum Ato Canberra ACT 0200 Australia Univ Paris 06 Lab Kastler Brossel F-75252 Paris France Univ Otago Dept Phys Dunedin New Zealand

We propose a scheme which encodes information in both the longitudinal and spatial transverse phases of a continuous-wave optical beam. A split detector-based interferometric scheme is then introduced to optimally detect both encoded phase signals. In contrast to present day optical storage devices, our phase coding scheme has an information storage capacity which scales with the power of the read-out optical beam. We analyze the maximum number of encoding possibilities at the shot noise limit (SNL). In addition, we show that using squeezed light, the SNL can be overcome and the number of encoding possibilities increased. We discuss a possible application of our phase-coding scheme for increasing the capacities of optical storage devices.

关键词： array detection interferometer multimode optical storage phase coding quantum noise limit split detection squeezing

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A fully integrated multi-channel detector for electron spectroscopy

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NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 2005年第1-4期238卷 219-223页

作者： Langstaff, DP Bushell, A Chase, T Evans, DA Univ Wales Inst Math & Phys Sci Aberystwyth SY23 3BZ Dyfed Wales

In electron spectroscopy, multi-channel detection combined with intense radiation sources provides the optimum experimental configuration. Building on the 5 mm, 192-channel ion detector developed at Aberystwyth, longer arrays have been fabricated for the detection of electrons in a commercial hemispherical analyser. The performance and reliability of a 10 mm, 384-detector array is discussed and the first array-detected photoelectron spectroscopy data for single-crystal diamond are presented. In scanning mode, the detector shows a large improvement compared to single channeltron detection and this improvement allows data to be collected in snapshot mode (I s per spectrum) to enable real-time measurements. (c) 2005 Elsevier B.V. All rights reserved.

关键词： real time XPS electron detector multianode array detection

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A fully integrated multi-channel detector for electron spectroscopy

A fully integrated multi-channel detector for electron spect...

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4th International Conference on Synchrotron Radiation in Materials Science (SRMS-4)

作者： Langstaff, DP Bushell, A Chase, T Evans, DA Univ Wales Inst Math & Phys Sci Aberystwyth SY23 3BZ Dyfed Wales

关键词： real time XPS electron detector multianode array detection

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Electrochemical detection method for nonelectroactive and electroactive analytes in microchip electrophoresis

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ANALYTICAL CHEMISTRY 2004年第23期76卷 6902-6907页

作者： Xu, JJ Bao, N Xia, XH Peng, Y Chen, HY Nanjing Univ Dept Chem Key Lab Life Analyt Chem Nanjing 210093 Peoples R China

In this work, we establish an indirect amperometric detection method via mounting a single carbon fiber disk working electrode in the end part of a microchannel. This in-channel configuration for microchip capillary electrophoresis brings about that the potential of the working electrode in the case of electrochemical reduction reaction is coupled by the separation electric field, while the potential of the working electrode in the case of electrochemical oxidation reaction is not coupled by the separation electric field. Such a special performance provides a convenient and sensitive approach for indirectly detecting nonelectroactive analytes that relies on amperometric response of dissolved oxygen in solution and directly detecting electroactive analytes based on their own amperometric response on the carbon fiber electrode. This method has shown its essential importance in the analysis of inorganic cations, biomolecules, and electroosmotic flow rates. Based on preliminary results, a detection limit of 1.0 muM for K+ and Na+ have been achieved.

关键词： CAPILLARY-ELECTROPHORESIS AMPEROMETRIC detection ELECTROLESS DEPOSITION array detection CHIPS SEPARATION DEVICE SYSTEMS ELECTROPHORESIS/ELECTROCHEMISTRY POLY(DIMETHYLSILOXANE)

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Inductively coupled plasma chemistry examinations with visible acousto-optic tunable filter hyperspectral imaging

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JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY 2004年第9期19卷 1151-1157页

作者： Bei, L Duffin, KL Carnahan, JW No Illinois Univ Dept Chem & Biochem De Kalb IL 60115 USA No Illinois Univ Dept Comp Sci De Kalb IL 60115 USA

Inductively coupled plasma optical emission spectrometry (ICP-OES) is widely used in trace-metal analysis. However, the behavior of this hot, ionized gas and effects on analyte excitation and ionization is not fully understood. To obtain sufficient information on the characteristics of plasma, two previous approaches, Abel inversion and tomography, have been used. Major drawbacks of these approaches include complex optical and data manipulation systems, significant amounts of time required for data collection, and long-term plasma drift and flicker. Initial examinations of an approach to alleviate many of these problems are presented. A hyperspectral imaging (HSI) system using an acousto-optic tunable filter (AOTF) as a wavelength selection device and a charge coupled device (CCD) camera as a detector is described. In these studies, the behavior of a visible paratellurite AOTF is presented. Six elements that yield intense emission lines in the visible wavelength region were examined. With in-house written software, plasma image background correction was achieved in a rapid fashion. Plasma chemistry was studied while varying plasma conditions including the applied rf power, nebulizer sample carrier gas flow, and liquid sample delivery rate. Results indicate that correlations between elemental excitation and ionization energies and the enhancements on emission intensities could be clearly discerned. It is demonstrated that the AOTF-HSI system has the potential to be a powerful tool for plasma chemistry research.

关键词： array detection ICP-AES SPECTROSCOPY SPECTROMETRY SYSTEM AR

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Quantification of isoflavones and lignans in serum using isotope dilution liquid chromatography/tandem mass spectrometry

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RAPID COMMUNICATIONS IN MASS SPECTROMETRY 2003年第12期17卷 1350-1357页

作者： Grace, PB Taylor, JI Botting, NP Fryatt, T Oldfield, MF Al-Maharik, N Bingham, SA MRC Dunn Human Nutr Unit Cambridge CB2 2XY England Univ St Andrews Sch Chem St Andrews KY16 9ST Fife Scotland

Phytoestrogens (isoflavones and lignans) are receiving increasing attention due to a potential protective effect against a number of complex diseases. However, in order to investigate these associations, it is necessary to accurately quantify the levels of phytoestrogens in foods and biological fluids. We report an assay for three isoflavones (daidzein, genistein, and glycitein), two metabolites of daidzein (O-desmethylangolensin and equol), and two lignans (enterodiol and enterolactone) in human serum using electrospray ionisation liquid chromatography/mass spectrometry (LC/MS) with selective reaction monitoring. A simple, highly automated sample preparation procedure requires only 200 muL of sample and utilises one solid-phase extraction stage. Limits of detection are in the region of 10 pg/mL for all analytes except equol, which had a limit of detection of approximately 100 pg/mL. The method developed is suitable for measuring the concentrations of phytoestrogens in blood samples collected from large epidemiological studies. The results of the analysis of serum samples from 300 men and women living in the UK are reported. Copyright (C) 2003 John Wiley Sons, Ltd.

关键词： Time-resolved fluoroimmunoassay Human urine Soy isoflavones Plasmaenterolactone Breast-cancer Phyto-estrogens Dietary phytoestrogens Postmenopausal women array detection Japanese men

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Capillary electrophoresis tandem mass spectrometry with array detection

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EUROPEAN MASS SPECTROMETRY 1999年第1期5卷 33-40页

作者： Deterding, LJ Tomer, KB Wellemans, JMY Cerny, RL Gross, ML NIEHS Struct Biol Lab Res Triangle Pk NC 27709 USA Univ Nebraska Dept Chem Lincoln NE 68588 USA

Mixtures of standard compounds of biological interest were analyzed by capillary electrophoresis in conjunction with tandem four-sector mass spectrometry (MS/MS) using an array detector. Capillary electrophoresis offers extremely high separation efficiencies while array detection allows for the simultaneous acquisition of a large fraction of a tandem mass spectrum and high utilization of the sample ions produced. Consequently, improvements in sensitivity and structural information were observed for the combined techniques in comparison to similar measurements with a four-sector and a single-point detector. Coaxial continuous-flow fast atom bombardment was used to create (M + H)(+) precursor ions of the separated analytes and their product ion spectra were acquired from femtomole levels in electrophoretic real-time, The limit-of-detection for the acquisition of MS/MS data from electrophoretically-separated peptides was 35-100 fmol, The MS/MS data acquired at these levels showed cleavages of the peptide backbone (i.e. to give a and y ions) and production of immonium ions from the constituent amino acids. Acquisition of the spectra via the array detector is more routine acid, at the 100 femtomole level, provides more structurally informative ions and yields better ion statistics than comparable spectra acquired with a point detector.

关键词： capillary electrophoresis tandem mass spectrometry array detection coaxial continuous flow FAB peptides

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Recent progress in high-performance anion-exchange chromatography ionspray mass spectrometry for molecular mass determination and characterization of carbohydrates using static and scanning array detection

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JOURNAL OF MASS SPECTROMETRY 1998年第4期33卷 377-386页

作者： van der Hoeven, RAM Tjaden, UR van der Greef, J van Casteren, WHM Schols, HA Voragen, AGJ Bruggink, C Leiden Univ Leiden Amsterdam Ctr Drug Res Div Analyt Chem NL-2300 RA Leiden Netherlands Agr Univ Wageningen Dept Food Technol & Nutr Sci Div Food Sci NL-6703 HD Wageningen Netherlands Dionex BV NL-4801 LH Breda Netherlands

Position-and time-resolved ion counting (PATRIC) array detection with a magnetic sector mass spectrometer equipped with an ionspray interface in the on-line coupling of high-performance anion-exchange chromatography (HPAEC) with mass spectrometry (MS) is described. PATRIC array detection is used in both the static and scanning mode for molecular mass determination and structure characterization caused by nozzle/skimmer-induced fragmentation in the ionspray interface. The virtual mass range is extended to over 7000 Da by the presence of triply and quadruply sodiated molecules in an enzyme digest of an exocellular polysaccharide (EPS) of Lactococcus lactis and quadruply sodiated molecules of beta-1,4-xglose oligomers. After optimization of the HPAEC/MS system, molecular mass information could be obtained down to similar to 700 pg per injection for each alpha-1,4-glucose oligomer up to a degree of polymerization of 7 using PATRIC array detection in the static mode. Structure information was obtained for alpha-1,4 glucose oligomers, galacturonic acid oligomers and an EPS digest using PATRIC array detection in the scanning mode. (C) 1998 John Wiley & Sons, Ltd.

关键词： high-performance anion-exchange chromatography ionspray mass spectrometry carbohydrates array detection multiple charging

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Infrared spectroscopy, microscopy, and microscopic imaging of mineralizing tissues: Spectra-structure correlations from human iliac crest biopsies

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JOURNAL OF BIOMEDICAL OPTICS 1999年第1期4卷 14-21页

作者： Mendelsohn, R Paschalis, EP Boskey, AL Rutgers State Univ Dept Chem Newark NJ 07102 USA Hosp Special Surg Mineralized Tissue Sect Div Res New York NY 10021 USA

Infrared microscopic images of the cortical region of human iliac crest biopsies have been obtained at: similar to 7 mu m spatial resolution and 8 cm(-1) spectral resolution with a 64 x 64 mercury-admium-telluride focal plane array detector coupled to a Fourier transform infrared microscope and a step scanning interferometer. Images of several spectral parameters provide information about the spatial distribution of the mineral (apatite) and protein (mostly collagen) components of the tissue. In addition, the image of a parameter known to reflect the crystallinity/perfection of the mineral phase, namely, the intensity ratio of bands at 1030 and 1020 cm(-1) within the phosphate nu(1), nu(3) contour, revealed a progressive increase in the apatite crystal size/perfection from the osteonal center to the periphery. Finally, a detailed comparison of the spatial distribution of the I(1020)/I(1030) ratio for the same osteon obtained by array detection and by conventional point-by-point microspectroscopy revealed statistically identical behavior, thereby providing a validation of infrared imaging for structural analysis of apatite forming tissues. (C) 1999 Society of Photo-Optical Instrumentation Engineers, S1083-3668(99)00101-X].

关键词： vibrational imaging array detection biomineralization hydroxyapatite collagen

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