mass spectrometry

(noun)

An analytical technique that measures the mass:charge ratio of the ions formed when a molecule or atom is ionized, vaporized, and introduced to a vacuum; may also involve breaking molecules into fragments, enabling structure to be determined.

Related Terms

(noun)

An analytical technique that measures the mass:charge ratio of the ions formed when a molecule or atom is ionized, vaporized, and introduced into a vacuum; may also involve breaking molecules into fragments, enabling structure to be determined.

Related Terms

Examples of mass spectrometry in the following topics:

  • Structural Determination

    • Structural determination using isotopes is often performed using nuclear magnetic resonance spectroscopy and mass spectrometry.
    • Structural determination utilizing isotopes is often performed using two analytical techniques: nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS).
    • Mass spectrometry is a technique for determining the molecular weight of an ionized molecule and fragments of the molecule that appear when the molecule is ionized.
    • Mass spectrometry and nuclear magnetic resonance detect the difference in an isotope's mass, while infrared spectroscopy detects the difference in the isotope's vibrational modes.
    • Nuclear magnetic resonance and mass spectrometry are used to investigate the mechanisms of chemical reactions.

  • Study of Photosynthesis

    • Mass spectrometry has been used to study the ratio of carbon isotopes in various plants to understand the mechanisms of photosynthesis.
    • Mass spectrometry has been used to study the ratio of isotopes in various plants to understand the mechanisms of photosynthesis.

  • Mass Spectrometry to Measure Mass

    • Mass spectrometry is a powerful characterization method that identifies elements, isotopes, and compounds based on mass-to-charge ratios.
    • Mass spectrometry (MS) is a powerful technique that can identify a wide variety of chemical compounds.
    • Mass spectrometers separate compounds based on a property known as the mass-to-charge ratio: the mass of the atom divided by its charge.
    • Depending on the information desired from mass spectrometry analysis, different ionization techniques may be used.
    • Mass analyzers separate the ions according to their mass-to-charge ratios.

  • High Resolution Spectra

    • In assigning mass values to atoms and molecules, we have assumed integral values for isotopic masses.
    • Thus, relative to 12C at 12.0000, the isotopic mass of 16O is 15.9949 amu (not 16) and 14N is 14.0031 amu (not 14).
    • By designing mass spectrometers that can determine m/z values accurately to four decimal places, it is possible to distinguish different formulas having the same nominal mass.
    • Mass spectrometry therefore not only provides a specific molecular mass value, but it may also establish the molecular formula of an unknown compound.
    • Tables of precise mass values for any molecule or ion are available in libraries; however, the mass calculator provided below serves the same purpose.

  • Experimental Determination of Reaction Rates

    • Common electrical methods include changes in the conductivity of a solution, the electrical potential in a cell, and mass spectrometry.

  • Isomers

    • Mass Spectrometry: This provides a molecular weight measurement accurate to less than 0.1 Da (atomic mass units).

  • Molar Mass of Compounds

    • The molar mass of a particular substance is the mass of one mole of that substance.
    • The mass of one mole of atoms of a pure element in grams is equivalent to the atomic mass of that element in atomic mass units (amu) or in grams per mole (g/mol).
    • Molar mass is the mass of a given substance divided by the amount of that substance, measured in g/mol.
    • The characteristic molar mass of an element is simply the atomic mass in g/mol.
    • However, molar mass can also be calculated by multiplying the atomic mass in amu by the molar mass constant (1 g/mol).

  • The Law of Conservation of Mass

    • The law of conservation of mass states that mass in an isolated system is neither created nor destroyed.
    • However, Antoine Lavoisier described the law of conservation of mass (or the principle of mass/matter conservation) as a fundamental principle of physics in 1789.
    • In other words, in a chemical reaction, the mass of the products will always be equal to the mass of the reactants.
    • This law was later amended by Einstein in the law of conservation of mass-energy, which describes the fact that the total mass and energy in a system remain constant.
    • However, the law of conservation of mass remains a useful concept in chemistry, since the energy produced or consumed in a typical chemical reaction accounts for a minute amount of mass.

  • Average Atomic Mass

    • The average atomic mass of an element is the sum of the masses of its isotopes, each multiplied by its natural abundance.
    • These different types of helium atoms have different masses (3 or 4 atomic mass units), and they are called isotopes.
    • Then, calculate the mass numbers.
    • To calculate the average atomic mass, multiply the fraction by the mass number for each isotope, then add them together.
    • Whenever we do mass calculations involving elements or compounds (combinations of elements), we always use average atomic masses.

  • Mass-to-Mole Conversions

    • Mass-to-mole conversions can be facilitated by employing the molar mass as a conversion ratio.
    • The relative atomic mass is a ratio between the average mass of an element and 1/12 of the mass of an atom of carbon-12.
    • From the relative atomic mass of each element, it is possible to determine each element's molar mass by multiplying the molar mass constant (1 g/mol) by the atomic weight of that particular element.
    • The molar mass value can be used as a conversion factor to facilitate mass-to-mole and mole-to-mass conversions.
    • The molar mass of water is 18 g/mol.