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  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. Electrospray ionization - Wikipedia

    en.wikipedia.org/wiki/Electrospray_ionization

    Electrospray ionization (ESI) is a technique used in mass spectrometry to produce ions using an electrospray in which a high voltage is applied to a liquid to create an aerosol. It is especially useful in producing ions from macromolecules because it overcomes the propensity of these molecules to fragment when ionized.

  4. Direct analysis in real time - Wikipedia

    en.wikipedia.org/wiki/Direct_analysis_in_real_time

    In positive ion mode, DART produces predominantly protonated molecules [M+H] + and in negative-ion mode deprotonated molecules [M-H] −. Both negative and positive modes of DART provides relatively simple mass spectra. Depending on the type of analyte, other species may be formed, such as multiple charged adducts. DART is categorized as a soft ...

  5. 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]

  6. Selected reaction monitoring - Wikipedia

    en.wikipedia.org/wiki/Selected_reaction_monitoring

    The ion is selected in the second mass spectrometry stage MS2 then undergoes further fragmentation to form ion D + which is selected in the third mass spectrometry stage MS3 and detected. Multiple reaction monitoring (MRM) is the application of selected reaction monitoring to multiple product ions from one or more precursor ions, [3] [4] for ...

  7. Ion source - Wikipedia

    en.wikipedia.org/wiki/Ion_source

    The mass/charge ratios of these secondary ions are measured with a mass spectrometer to determine the elemental, isotopic, or molecular composition of the surface to a depth of 1 to 2 nm. In a liquid metal ion source (LMIS), a metal (typically gallium ) is heated to the liquid state and provided at the end of a capillary or a needle.

  8. 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]

  9. Mass spectrum - Wikipedia

    en.wikipedia.org/wiki/Mass_spectrum

    A mass spectrum is a histogram plot of intensity vs. mass-to-charge ratio (m/z) in a chemical sample, [1] usually acquired using an instrument called a mass spectrometer. Not all mass spectra of a given substance are the same; for example, some mass spectrometers break the analyte molecules into fragments ; others observe the intact molecular ...

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