The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Robert C. Murphy - One of the best experts on this subject based on the ideXlab platform.

  • analysis of polyunsaturated aminophospholipid molecular species using isotope tagged derivatives and tandem Mass Spectrometry Mass Spectrometry Mass Spectrometry
    Analytical Biochemistry, 2006
    Co-Authors: Karin Zemski A Berry, Robert C. Murphy
    Abstract:

    Abstract When aminophospholipids with only saturated and monounsaturated fatty acids esterified to the glycerol backbone were labeled with isotopically enriched N-methylpiperazine acetic acid N-hydroxysuccinimide ester reagents, it was found that they could be readily detected as N-methylpiperazine-amide-tagged aminophospholipids using a precursor scan of the stable isotope reporter ion (m/z 114–117) formed by tandem Mass Spectrometry/Mass Spectrometry. However, it was found in the current study that these precursor ion scans are not useful in determining the changes of aminophospholipids with polyunsaturated fatty acids (PUFAs) esterified to the glycerol backbone due to the presence of interfering ions in the reporter ion region. Therefore, a method was developed using tandem Mass Spectrometry/Mass Spectrometry/Mass Spectrometry (MS3) to obtain reporter ion ratios that were not distorted by interfering ions present in the collision-induced dissociation spectra of nontagged aminophospholipids with PUFAs. This new MS3 method for N-methylpiperazine- amide-tagged aminophospholipids was used to examine the fate of diacyl, ether, or plasmalogen glycerophosphoethanolamine (GPEtn) species after exposure of human polymorphonuclear leukocytes to A23187 and granulocyte macrophage–colony-stimulating factor/formyl-methionyl-leucyl-phenylalanine stimuli, which can induce eicosanoid biosynthesis, to follow those GPEtn molecular species which were the source of arachidonic acid released. Upon stimulation of the human polymorphonuclear leukocyte, it was found that the abundant arachidonoyl GPEtn plasmalogen molecular species were uniquely reduced in relative content compared to ether or diacyl species and this subclass of GPEtn may be a source of the arachidonic acid converted to leukotrienes by the 5-lipoxygenase pathway activated in this cell.

  • electrospray Mass Spectrometry of phospholipids
    Mass Spectrometry Reviews, 2003
    Co-Authors: Melissa K Pulfer, Robert C. Murphy
    Abstract:

    Phospholipids play a central role in the biochemistry of all living cells. These molecules constitute the lipid bilayer defining the outer confines of a cell, but also serve as the structural entities which confine subcellular components. Mass Spectrometry has emerged as a powerful tool useful for the qualitative and quantitative analysis of complex phospholipids, including glycerophospholipids and the sphingolipid, sphingomyelin. Collision induced decomposition of both positive and negative molecular ion species yield rich information as to the polar head group of the phospholipid and the fatty-acyl substituents esterified to the glycerophospholipid backbone. This review presents the current level of understanding of the mechanisms involved in the formation of various product ions following collisional activation of molecular ion species generated by electrospray ionization of the common glycerophospholipids, including phosphatidic acid, phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol, phosphatidylglycerol, phosphatidylserine, cardiolipin, and sphingomyelin. Recent advances in the application of matrix assisted laser desorption ionization is also considered. Several applications of Mass Spectrometry applied to phospholipid analysis are presented as they apply to physiology as well as pathophysiology.

Kerri A. Pratt - One of the best experts on this subject based on the ideXlab platform.

  • Mass Spectrometry of atmospheric aerosols recent developments and applications part i off line Mass Spectrometry techniques
    Mass Spectrometry Reviews, 2012
    Co-Authors: Kerri A. Pratt, Kimberly A Prather
    Abstract:

    Many of the significant advances in our understanding of atmospheric particles can be attributed to the application of Mass Spectrometry. Mass Spectrometry provides high sensitivity with fast response time to probe chemically complex particles. This review focuses on recent developments and applications in the field of Mass Spectrometry of atmospheric aerosols. In Part II of this two-part review, we concentrate on real-time Mass Spectrometry techniques, which provide high time resolution for insight into brief events and diurnal changes while eliminating the potential artifacts acquired during long-term filter sampling. In particular, real-time Mass Spectrometry has been shown recently to provide the ability to probe the chemical composition of ambient individual particles <30 nm in diameter to further our understanding of how particles are formed through nucleation in the atmosphere. Further, transportable real-time Mass Spectrometry techniques are now used frequently on ground-, ship-, and aircraft-based studies around the globe to further our understanding of the spatial distribution of atmospheric aerosols. In addition, coupling aerosol Mass Spectrometry techniques with other measurements in series has allowed the in situ determination of chemically resolved particle effective density, refractive index, volatility, and cloud activation properties. © 2011 Wiley Periodicals, Inc., Mass Spec Rev 31:17–48, 2012

  • Mass Spectrometry of atmospheric aerosols recent developments and applications part ii on line Mass Spectrometry techniques
    Mass Spectrometry Reviews, 2012
    Co-Authors: Kerri A. Pratt, Kimberly A Prather
    Abstract:

    Many of the significant advances in our understanding of atmospheric particles can be attributed to the application of Mass Spectrometry. Mass Spectrometry provides high sensitivity with fast response time to probe chemically complex particles. This review focuses on recent developments and applications in the field of Mass Spectrometry of atmospheric aerosols. In Part II of this two-part review, we concentrate on real-time Mass Spectrometry techniques, which provide high time resolution for insight into brief events and diurnal changes while eliminating the potential artifacts acquired during long-term filter sampling. In particular, real-time Mass Spectrometry has been shown recently to provide the ability to probe the chemical composition of ambient individual particles <30 nm in diameter to further our understanding of how particles are formed through nucleation in the atmosphere. Further, transportable real-time Mass Spectrometry techniques are now used frequently on ground-, ship-, and aircraft-based studies around the globe to further our understanding of the spatial distribution of atmospheric aerosols. In addition, coupling aerosol Mass Spectrometry techniques with other measurements in series has allowed the in situ determination of chemically resolved particle effective density, refractive index, volatility, and cloud activation properties.

Kimberly A Prather - One of the best experts on this subject based on the ideXlab platform.

  • Mass Spectrometry of atmospheric aerosols recent developments and applications part i off line Mass Spectrometry techniques
    Mass Spectrometry Reviews, 2012
    Co-Authors: Kerri A. Pratt, Kimberly A Prather
    Abstract:

    Many of the significant advances in our understanding of atmospheric particles can be attributed to the application of Mass Spectrometry. Mass Spectrometry provides high sensitivity with fast response time to probe chemically complex particles. This review focuses on recent developments and applications in the field of Mass Spectrometry of atmospheric aerosols. In Part II of this two-part review, we concentrate on real-time Mass Spectrometry techniques, which provide high time resolution for insight into brief events and diurnal changes while eliminating the potential artifacts acquired during long-term filter sampling. In particular, real-time Mass Spectrometry has been shown recently to provide the ability to probe the chemical composition of ambient individual particles <30 nm in diameter to further our understanding of how particles are formed through nucleation in the atmosphere. Further, transportable real-time Mass Spectrometry techniques are now used frequently on ground-, ship-, and aircraft-based studies around the globe to further our understanding of the spatial distribution of atmospheric aerosols. In addition, coupling aerosol Mass Spectrometry techniques with other measurements in series has allowed the in situ determination of chemically resolved particle effective density, refractive index, volatility, and cloud activation properties. © 2011 Wiley Periodicals, Inc., Mass Spec Rev 31:17–48, 2012

  • Mass Spectrometry of atmospheric aerosols recent developments and applications part ii on line Mass Spectrometry techniques
    Mass Spectrometry Reviews, 2012
    Co-Authors: Kerri A. Pratt, Kimberly A Prather
    Abstract:

    Many of the significant advances in our understanding of atmospheric particles can be attributed to the application of Mass Spectrometry. Mass Spectrometry provides high sensitivity with fast response time to probe chemically complex particles. This review focuses on recent developments and applications in the field of Mass Spectrometry of atmospheric aerosols. In Part II of this two-part review, we concentrate on real-time Mass Spectrometry techniques, which provide high time resolution for insight into brief events and diurnal changes while eliminating the potential artifacts acquired during long-term filter sampling. In particular, real-time Mass Spectrometry has been shown recently to provide the ability to probe the chemical composition of ambient individual particles <30 nm in diameter to further our understanding of how particles are formed through nucleation in the atmosphere. Further, transportable real-time Mass Spectrometry techniques are now used frequently on ground-, ship-, and aircraft-based studies around the globe to further our understanding of the spatial distribution of atmospheric aerosols. In addition, coupling aerosol Mass Spectrometry techniques with other measurements in series has allowed the in situ determination of chemically resolved particle effective density, refractive index, volatility, and cloud activation properties.

Michael K Hoffman - One of the best experts on this subject based on the ideXlab platform.

  • determination of chloramphenicol in animal tissues and urine liquid chromatography tandem Mass Spectrometry versus gas chromatography Mass Spectrometry
    Analytica Chimica Acta, 2003
    Co-Authors: Alex Gantverg, Isaac Shishani, Michael K Hoffman
    Abstract:

    Abstract A very sensitive method was developed for detection and confirmation of chloramphenicol (CAP) in equine, porcine and bovine muscle and urine. The method included ethyl acetate extraction of CAP followed by a two-step C18 solid-phase clean up; recovery was >80%. Extracted CAP was determined by liquid chromatography–tandem Mass Spectrometry (LC–MS/MS) in negative atmospheric pressure chemical ionization mode. LC–MS/MS gave superior sensitivity and selectivity compared to that shown by gas chromatography–Mass Spectrometry (GC–MS) in electron impact mode. Even in a “dirty” matrix, such as urine, the estimated CAP detection limit for LC–MS/MS detection was 0.02 μg kg −1 while the corresponding value for GC–MS was only 2 μg kg −1 .

Takeshi Yasumoto - One of the best experts on this subject based on the ideXlab platform.

  • electrospray ionization Mass Spectrometry of tetrodotoxin and its analogs liquid chromatography Mass Spectrometry tandem Mass Spectrometry and liquid chromatography tandem Mass Spectrometry
    Analytical Biochemistry, 2001
    Co-Authors: Yuki Shoji, Mari Yotsuyamashita, Teruo Miyazawa, Takeshi Yasumoto
    Abstract:

    Abstract Tetrodotoxin (TTX), a powerful sodium channel blocker, usually exists as a mixture of its analogs (TTXs) in natural sources. Due to the structural variation, some analogs are difficult to detect using the postcolumn liquid chromatography-fluorescent detection (LC-FLD) system. Liquid chromatography/electrospray ionization Mass Spectrometry (LC/ESI-MS) analysis of TTXs can be achieved by a combination of chromatography on a reversed-phase column with long carbon chains (C30) and the mobile phase containing an ion pair reagent (ammonium heptafluorobutyrate). The relationship between the amount of applied standard TTX and its peak area on the Mass chromatogram (m/z 320) showed good linearity over a range of 50–1000 pmol. The detection limit for TTX in the selected ion monitoring (SIM) mode was estimated to be 0.7 pmol (signal to noise ratio: 2). The tandem Mass Spectrometry (MS/MS) scan for the fragment ions of eight TTXs arising from the molecular ions provided characteristic spectra, and the structures of the origins of the prominent fragment ions were proposed. The intense fragment ions of TTX and 11-deoxyTTX were applicable to LC/MS/MS operated in the selected reaction monitoring mode. This method might be useful for further identification of TTXs.