Flashcards
Module 7: Introduction into Mass Spectrometry
Cards in this deck (17)
- 1mass spectrometrytechnique for studying the masses of atoms or molecules or fragments of molecules. perform 3 universal functions: create, separate, detect
- 2what does MS generate?a mass spectrum that is characteristic of an analyte; plot of abundance (y) vs. the mass-to-charge ration of ions (x)
- 3mass-to-charge ratio (m/z)the mass of given ion divided by the # of elementary charges
- 4base peakpeak with the greatest intensity. may or may not be the molecular ion
- 5product ionsions that arise from dissociation of a precursor ion. also referred to as fragment or daughter ions
- 6molecular ionion formed by the removal from (+ve ions) or addition to (-ve) a molecule of one or more e- w/out fragmentation of the molecular structure
- 7precursor ionion that dissociates to form product ions. precursor ions may or may not be the molecular ion
- 8atomic massweighted avg of the masses of the isotopes of an element.
- 9molecular masssum of the unified atomic mass units of a molecule or ion
- 10nominal massinteger mass of the mass of the most abundant isotope of each element in an ion or molecule
- 11what is the 1st stage of MS?creating ions
- 12electron ionization (EI)most common; e- are emitted from a heated filament with an energy of 70eV. neutral analyte molecules enter the ion source orthogonal to beam of e-; molecules bombarded with e- and become ionized
- 13what drives ionization in EIdriven by analyte's ionization energy (IE); which is the min. amount of energy required to remove an e- from the molecule in the gaseous state
- 14which is the first e- lost?electrons with smallest IE will be lost first
- 15bc of the energy of the ion beam is typically so much greater than the IE of the neutral analyte, the molecular ion formed will typically have an excess of what?internal energy, this causes the molecular ion to break apart and form fragment ions (product ions)
- 16chemical ionization (CI)neutral analytes are ionized by an induced chemical rxn with a reagent gas- purposely bled into the ion source and ionized by EI; results in less fragmentation
- 17—
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- Flashcards on Module 7: Introduction into Mass Spectrometry , created by angeli Fernandez on 11/11/2022.
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