The Experts below are selected from a list of 114477 Experts worldwide ranked by ideXlab platform

Mark R. Emmett - One of the best experts on this subject based on the ideXlab platform.

Christopher L. Hendrickson - One of the best experts on this subject based on the ideXlab platform.

Renato Zenobi - One of the best experts on this subject based on the ideXlab platform.

  • Secondary Electrospray Ionization
    Breathborne Biomarkers and the Human Volatilome, 2020
    Co-Authors: Jiayi Lan, Francisco Blanco Parte, Guillermo Vidal-de-miguel, Renato Zenobi
    Abstract:

    Abstract Secondary Electrospray Ionization (SESI) is a relatively new member of the family of methods for analyzing breathborne biomarkers and exploring the human volatilome. SESI has generated considerable interest in the community due to its sensitivity and its ability to detect compounds with molecular weights up to 1000 Da. A SESI source consists of a nanoElectrospray that produces a cloud of charged species in a small volume at atmospheric pressure, which is mixed with the gas (e.g., breath) carrying the analytes of interest such that charge is transferred from the charging agents to the analyte molecules. This chapter will outline the technical aspects of SESI and present an up-to-date account of applications of this technology for exhaled breath analysis.

  • extractive Electrospray Ionization mass spectrometry enhanced sensitivity using an ion funnel
    Analytical Chemistry, 2012
    Co-Authors: Lukas Meier, Christian Berchtold, Stefan Schmid, Renato Zenobi
    Abstract:

    Electrodynamic ion funnel interfaces for Electrospray Ionization (ESI) have shown to enhance the sensitivity of measurements by more than 2 orders of magnitude in the intermediate pressure region of the instrument (1–30 Torr). In this study, we use an ion funnel at ambient pressure to enhance the sensitivity of extractive Electrospray Ionization (EESI) by spraying directly into the ion funnel. EESI is a powerful Ionization technique that is capable of handling complex matrixes that may contain dozens of compounds. Our results using atenolol, salbutamol, and cocaine as test compounds show that we can improve the limit of detection for these compounds by more than 3 orders of magnitude compared to standard EESI experiments.

  • Extractive Electrospray Ionization Mass Spectrometry—Enhanced Sensitivity Using an Ion Funnel
    Analytical Chemistry, 2012
    Co-Authors: Lukas Meier, Christian Berchtold, Stefan Schmid, Renato Zenobi
    Abstract:

    Electrodynamic ion funnel interfaces for Electrospray Ionization (ESI) have shown to enhance the sensitivity of measurements by more than 2 orders of magnitude in the intermediate pressure region of the instrument (1–30 Torr). In this study, we use an ion funnel at ambient pressure to enhance the sensitivity of extractive Electrospray Ionization (EESI) by spraying directly into the ion funnel. EESI is a powerful Ionization technique that is capable of handling complex matrixes that may contain dozens of compounds. Our results using atenolol, salbutamol, and cocaine as test compounds show that we can improve the limit of detection for these compounds by more than 3 orders of magnitude compared to standard EESI experiments.

Joseph A. Loo - One of the best experts on this subject based on the ideXlab platform.

  • Positive ion Electrospray Ionization mass spectrometry of oligonucleotides
    Journal of the American Society for Mass Spectrometry, 1997
    Co-Authors: Kristin A. Sannes-lowery, David P. Mack, Houng-yau Mei, Joseph A. Loo
    Abstract:

    Positive ion Electrospray Ionization mass spectra have been obtained of deoxyribonucleic acids (DNA) and ribonucleic acids (RNA), including transfer RNAs (77-mer, ∼ 25 kDa). For several different solution conditions, the charge state distributions of DNA and RNA molecules were determined. It is postulated that the production of the multiply charged positive ions results from gas phase dissociation of complexes between nitrogen-containing bases and oligonucleotides.

  • studying noncovalent protein complexes by Electrospray Ionization mass spectrometry
    Mass Spectrometry Reviews, 1997
    Co-Authors: Joseph A. Loo
    Abstract:

    Electrospray Ionization mass spectrometry has been used to study protein interactions driven by noncovalent forces. The gentleness of the Electrospray Ionization process allows intact protein complexes to be directly detected by mass spectrometry. Evidence from the growing body of literature suggests that the ESI-MS observations for these weakly bound systems reflect, to some extent, the nature of the interaction found in the condensed phase. Stoichiometry of the complex can be easily obtained from the resulting mass spectrum because the molecular weight of the complex is directly measured. For the study of protein interactions, ESI-MS is complementary to other biophysical methods, such as NMR and analytical ultracentrifugation. However, mass spectrometry offers advantages in speed and sensitivity. The experimental variables that play a role in the outcome of ESI-MS studies of noncovalently bound complexes are reviewed. Several applications of ESI-MS are discussed, including protein interactions with metal ions and nucleic acids and subunit protein structures (quaternary structure). © 1997 John Wiley & Sons, Inc., Mass Spectrom Rev 16(1), 25–49, 1997

  • Use of Electrospray Ionization mass spectrometry to probe antisense peptide interactions
    Biological mass spectrometry, 1994
    Co-Authors: Joseph A. Loo, Daniel D. Holsworth, Robert Root-bernstein
    Abstract:

    Electrospray Ionization mass spectrometry with a magnetic sector instrument has been used to test for non-covalent interactions between human angiotensin II (M(r) 1046) and eight synthetic octapeptides that are considered complementary peptides (encoded by DNA sequences complementary to the DNA sequence that codes for human angiotensin II) or analogues of these antisense peptides. The relative abundance of the doubly charged heterodimer complex broadly correlates to the trend observed with solution-phase studies such as 1H nuclear magnetic resonance. Dissociation constants for the reaction in solution are in the high micromolar range. Electrospray Ionization can potentially be a sensitive method for rapidly screening weak molecular interactions. Further work is necessary to study the possible gas-phase contributions to the observed binding interactions indicated in the mass spectrometry data.

Zhong-ping Yao - One of the best experts on this subject based on the ideXlab platform.

  • Mobility of Proteins in Porous Substrates under Electrospray Ionization Conditions
    Analytical chemistry, 2016
    Co-Authors: Zhong-ping Yao
    Abstract:

    Proteins are important substances in living organisms and characterization of proteins is an indispensible part for protein study. Analysis of proteins using Electrospray Ionization-mass spectrometry (ESI-MS) with porous substrates was investigated in this study. The results revealed that the Ionization process had two stages. At the first stage, mobility and resulting spectra of proteins were similar to those obtained with conventional capillary-based ESI-MS. At the second stage, hydrophobic–hydrophobic interactions between proteins and the tip surfaces played an important role in mobility and detectability of protein ions, which were size and shape dependent, and a linear relationship could be found between the peak area of selected ion chromatogram and the cross section of protein ions. Preparative separation of proteins could be achieved by collecting the proteins remained on the porous substrates. These results led us to propose that Electrospray Ionization from porous substrates offer a potential ap...

  • Electrospray Ionization on Solid Substrates
    Mass spectrometry (Tokyo Japan), 2014
    Co-Authors: Zhong-ping Yao
    Abstract:

    Development of Electrospray Ionization on solid substrates (solid-substrate ESI) avoids the clogging problem encountered in conventional capillary-based ESI, allows more convenient sampling and permits new applications. So far, solid-substrate ESI with various materials, e.g., metals, paper, wood, fibers and biological tissue, has been developed, and applications ranging from analysis of pure compounds to complex mixtures as well as in vivo study were demonstrated. Particularly, the capability of solid-substrate ESI in direct analysis of complex samples, e.g., biological fluids and foods, has significantly facilitated mass spectrometric analysis in real-life applications and led to increasingly important roles of these techniques nowadays. In this review, various solid-substrate ESI techniques and their applications are summarized and the prospects in this field are discussed.