When.com Web Search

Search results

  1. Results From The WOW.Com Content Network
  2. Mass spectrometry - Wikipedia

    en.wikipedia.org/wiki/Mass_spectrometry

    Mass spectrometry data analysis is specific to the type of experiment producing the data. General subdivisions of data are fundamental to understanding any data. Many mass spectrometers work in either negative ion mode or positive ion mode. It is very important to know whether the observed ions are negatively or positively charged.

  3. Chemical ionization - Wikipedia

    en.wikipedia.org/wiki/Chemical_ionization

    Peroxynitrate chemical ionization mass spectrometer at the US National Oceanic and Atmospheric Administration. CI mass spectrometry is a useful tool in structure elucidation of organic compounds. [3] This is possible with CI, because formation of [M+1] + eliminates a stable molecule, which can be used to guess the functional groups present. [3]

  4. Direct analysis in real time - Wikipedia

    en.wikipedia.org/wiki/Direct_analysis_in_real_time

    In mass spectrometry, direct analysis in real time (DART) is an ion source that produces electronically or vibronically excited-state species from gases such as helium, argon, or nitrogen that ionize atmospheric molecules or dopant molecules. The ions generated from atmospheric or dopant molecules undergo ion-molecule reactions with the sample ...

  5. Atmospheric-pressure chemical ionization - Wikipedia

    en.wikipedia.org/wiki/Atmospheric-pressure...

    Atmospheric pressure chemical ionization chamber cross section. Atmospheric pressure chemical ionization (APCI) is an ionization method used in mass spectrometry which utilizes gas-phase ion-molecule reactions at atmospheric pressure (10 5 Pa), [1] [2] commonly coupled with high-performance liquid chromatography (HPLC). [3]

  6. Mass spectrum - Wikipedia

    en.wikipedia.org/wiki/Mass_spectrum

    The x-axis of a mass spectrum represents a relationship between the mass of a given ion and the number of elementary charges that it carries. This is written as the IUPAC standard m/z to denote the quantity formed by dividing the mass of an ion (in daltons) by the dalton unit and by its charge number (positive absolute value).

  7. Ion source - Wikipedia

    en.wikipedia.org/wiki/Ion_source

    Plasma desorption ionization mass spectrometry (PDMS), also called fission fragment ionization, is a mass spectrometry technique in which ionization of material in a solid sample is accomplished by bombarding it with ionic or neutral atoms formed as a result of the nuclear fission of a suitable nuclide, typically the californium isotope 252 Cf ...

  8. Selected-ion flow-tube mass spectrometry - Wikipedia

    en.wikipedia.org/wiki/Selected-ion_flow-tube...

    In the selected ion flow tube mass spectrometer, SIFT-MS, ions are generated in a microwave plasma ion source, usually from a mixture of laboratory air and water vapor. . From the formed plasma, a single ionic species is selected using a quadrupole mass filter to act as "precursor ions" (also frequently referred to as primary or reagent ions in SIFT-MS and other processes involving chemical ...

  9. Field desorption - Wikipedia

    en.wikipedia.org/wiki/Field_desorption

    Schematic of field desorption ionization with emitter at left and mass spectrometer at right. Field desorption (FD) is a method of ion formation used in mass spectrometry (MS) in which a high-potential electric field is applied to an emitter with a sharp surface, such as a razor blade, or more commonly, a filament from which tiny "whiskers" have formed.