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CH3F2 Mass Spectrometry Basics Quiz
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CH3F2 Mass Spectrometry Basics Quiz

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Questions and Answers

What is the formula to calculate the total charge (q) in a mass spectrometer?

  • q = z + e
  • q = z * e (correct)
  • q = z / e
  • q = z ^ e

    • What is the purpose of having a vacuum system in a mass spectrometer?

  • To increase collisions between ions and the gas
  • To decrease the need for ionization
  • To decrease collisions between ions and the gas (correct)
  • To increase atmospheric pressure

    • What is the function of an ionization method in a mass spectrometer?

  • To measure the intensity of signals
  • To analyze mass spectra
  • To convert compounds into gas-phase ions (correct)
  • To avoid collisions between ions and gas

    • Which unit is used to measure mass in the context of mass spectrometry?

    <p>Dalton (Da)</p> Signup and view all the answers

    Why do isotopes of an element have different mass-to-charge ratios in a mass spectrometer?

    <p>Because they have different numbers of neutrons</p> Signup and view all the answers

    What does FWHM stand for in the context of mass spectrometry?

    <p>Full Width at Half Maximum</p> Signup and view all the answers

    Which type of mass spectrometer typically has a resolving power of approximately 500,000+ (FWHM)?

    <p>FTICR</p> Signup and view all the answers

    What is the resolving power of Orbitrap mass spectrometers approximately?

    <p>~200,000</p> Signup and view all the answers

    What is the resolving power for the Isotopic fine structure of 15N with a m/z value of 1348?

    <p>~4,500,000</p> Signup and view all the answers

    What is the meaning of FWHM when referring to the resolving power in mass spectrometry?

    <p>Full Width at Half Maximum</p> Signup and view all the answers

    What is the formula for calculating the probability P(i) of having the ith isotope in mass spectrometry?

    <p>P(i) = pi(1 - p)N-i i!(N-i)!N</p> Signup and view all the answers

    In the context of natural isotopic abundance, what is the approximate percentage of 13C?

    <p>~1.1%</p> Signup and view all the answers

    What does mass accuracy measure in mass spectrometry?

    <p>Confidence level in assignment</p> Signup and view all the answers

    Which factor increases the number of possible assignments (molecular formulae) for a peak in mass spectrometry?

    <p>Increasing m/z error tolerance</p> Signup and view all the answers

    What is the significance of having better mass accuracy in mass spectrometry measurements?

    <p>It increases the confidence in assignment</p> Signup and view all the answers

    What is the electron energy typically used in Electron Ionization (EI) in mass spectrometry?

    <p>70 eV</p> Signup and view all the answers

    Which ionization method in mass spectrometry is specifically mentioned as not suitable for peptides, proteins, and other biomolecules?

    <p>Electron Ionization (EI)</p> Signup and view all the answers

    In Matrix-assisted Laser Desorption/Ionization (MALDI), what is the typical ratio of matrix to analyte?

    <p>1000s-to-1</p> Signup and view all the answers

    Which type of ions are typically observed in Matrix-assisted Laser Desorption/Ionization (MALDI) as protonated species or adducts with metals?

    <p>[M+H]+, [M+Na]+, [M+K]+</p> Signup and view all the answers

    Which ionization method in mass spectrometry involves the use of a laser to ablate a surface without the use of a matrix?

    <p>Laser Desorption/Ionization (LDI)</p> Signup and view all the answers

    What is the relationship between the frequency of ions and their mass-to-charge ratio (m/z) in an Orbitrap mass spectrometer?

    <p>Inversely proportional</p> Signup and view all the answers

    Which type of mass spectrometer requires the use of cryogens for the magnet and ultrahigh vacuum (UHV)?

    <p>Fourier transform ion cyclotron resonance (FTICR)</p> Signup and view all the answers

    In terms of resolving power, what is a major disadvantage of Quadrupole/ion trap mass spectrometers?

    <p>Limited resolving power</p> Signup and view all the answers

    Which type of mass spectrometer offers the best mass accuracy but is slow and expensive?

    <p>Orbitrap</p> Signup and view all the answers

    What is a significant advantage of Time-of-flight (TOF) mass spectrometers compared to other types?

    <p>Fast data acquisition rate</p> Signup and view all the answers

    What is a distinguishing feature of Fourier transform ion cyclotron resonance (FTICR) mass spectrometers when compared to Orbitrap?

    <p>Superconducting magnet used</p> Signup and view all the answers

    In time-of-flight mass spectrometry, what does the square of the time taken to reach the detector indicate?

    <p>The mass-to-charge ratio of the ion</p> Signup and view all the answers

    What is the main advantage of using a pulsed experiment in time-of-flight mass spectrometry?

    <p>Reduced temporal spread in ions from small kinetic energy differences</p> Signup and view all the answers

    What is the relationship between the mass-to-charge ratio (m/z) and the time taken for ions to reach the detector in time-of-flight mass spectrometry?

    <p>m/z is directly proportional to the square of time</p> Signup and view all the answers

    What instrument type in Fourier transform mass spectrometry involves detecting ion motion rather than ions hitting a detector?

    <p>Fourier transform ion cyclotron resonance (FTICR)</p> Signup and view all the answers

    How does orthogonal time-of-flight (TOF) enable the use of continuous ion sources?

    <p>By reducing temporal spread due to kinetic energy differences</p> Signup and view all the answers

    What property of ions does the accelerating potential (Vacc) represent in time-of-flight mass spectrometry?

    <p>Kinetic energy of the ions</p> Signup and view all the answers

    What is the term used to describe the motion of a charged particle, such as an ion, around the center of the magnetic field axis?

    <p>Cyclotron motion</p> Signup and view all the answers

    In the context of ion cyclotron resonance (FT-ICR), what is the cyclotron frequency proportional to?

    <p>The mass of the ion</p> Signup and view all the answers

    What is the relationship between the frequency of an ion and the mass-to-charge ratio in a cyclotron?

    <p>Frequency is inversely proportional to mass</p> Signup and view all the answers

    What parameter determines the cyclotron frequency of an ion in a magnetic field?

    <p>The magnetic field strength</p> Signup and view all the answers

    What does 'FT-ICR' stand for in the context of ion cyclotron resonance?

    <p>Fourier Transformation - Ion Cyclotron Resonance</p> Signup and view all the answers

    What is the significance of the charge per electron in determining the cyclotron frequency of an ion?

    <p>It indirectly affects the mass-to-charge ratio</p> Signup and view all the answers

    What is the unit of measurement for electric potential?

    <p>Volt (V)</p> Signup and view all the answers

    In mass spectrometry, what is the function of a quadrupole analyzer?

    <p>Scan ions one at a time</p> Signup and view all the answers

    What is the primary difference between sector instruments and ion trap instruments in mass spectrometry?

    <p>Ion trap instruments trap ions in motion, while sector instruments scan ions continuously.</p> Signup and view all the answers

    What does increasing the amplitude of RF and DC do in a quadrupole analyzer?

    <p>Increases poor resolution and loss of accuracy</p> Signup and view all the answers

    What is the fundamental principle of time-of-flight (TOF) instruments in mass spectrometry?

    <p>Ions reaching the detector at different times based on their mass/charge ratio</p> Signup and view all the answers

    What is the role of gravitational potential energy in mass spectrometry?

    <p>Stores energy due to object's position</p> Signup and view all the answers

    How does increasing the amplitude of RF and DC affect resolution in mass spectrometry?

    <p>Worsens resolution and negatively impacts accuracy</p> Signup and view all the answers

    What is the primary difference between ion traps and quadrupoles in mass spectrometry?

    <p>Ion traps scan ions simultaneously, while quadrupoles trap ions one at a time.</p> Signup and view all the answers

    What effect does additional energy have on the electron ionization in mass spectrometry?

    <p>It increases fragmentation</p> Signup and view all the answers

    In mass spectrometry, what type of ions are radical ions characterized by?

    <p>They have an unpaired electron</p> Signup and view all the answers

    What is a key difference between odd electron ions and even electron ions in mass spectrometry?

    <p>Odd electron ions lead to smaller fragments</p> Signup and view all the answers

    What type of mass spectrometry involves intentional fragmentation to obtain structural information?

    <p>Tandem mass spectrometry</p> Signup and view all the answers

    What role does the isolation step play in tandem mass spectrometry?

    <p>It allows for determination of which fragment came from which precursor</p> Signup and view all the answers

    What is the significance of the high electron ionization energy compared to the ionization energy for a molecule?

    <p>It increases fragmentation in mass spectrometry</p> Signup and view all the answers

    What does Collision-induced dissociation (CID) in tandem mass spectrometry involve?

    <p>Ions colliding with neutral gases and dissociating</p> Signup and view all the answers

    What is the most common method used for multiple steps of fragmentation in tandem mass spectrometry?

    <p>Collision-induced dissociation (CID)</p> Signup and view all the answers

    In Collision-induced dissociation (CID), what factor controls the energy of the collision?

    <p>Kinetic energy of the ion</p> Signup and view all the answers

    Which formula represents the center-of-mass collision energy (Ecom) in Collision-induced dissociation (CID)?

    <p>$Ecom = \frac{mp}{mN}Elab$</p> Signup and view all the answers

    What type of collision energy does Collision-induced dissociation (CID) focus on?

    <p>Centre-of-mass collision energy</p> Signup and view all the answers

    In tandem mass spectrometry, what is the key parameter responsible for determining the collision energy between ions and neutral gases?

    <p>Kinetic energy of the ion chosen by the user</p> Signup and view all the answers

    Which type of ions are typically observed in time-of-flight mass spectrometry as having an odd electron?

    <p>Odd electron ion</p> Signup and view all the answers

    In mass spectrometry, which effect is responsible for the stability of a carbocation with methyl groups attached?

    <p>Inductive effect</p> Signup and view all the answers

    What type of compounds are known to exhibit difficulty in fragmentation in mass spectrometry?

    <p>Aromatic systems</p> Signup and view all the answers

    Which group is considered an electron-withdrawing group when examining resonance effects in mass spectrometry?

    <p>-NO2</p> Signup and view all the answers

    What type of cleavage occurs when two electrons are moved to the same atom during dissociation in mass spectrometry?

    <p>Heterolytic cleavage</p> Signup and view all the answers

    In mass spectrometry, which functional group is commonly associated with the loss of CO2 and HCOOH upon dissociation?

    <p>Acid groups</p> Signup and view all the answers

    What aspect of ions does the accelerating potential (Vacc) in time-of-flight mass spectrometry represent?

    <p>Kinetic energy</p> Signup and view all the answers

    In the context of mass spectrometry, what property determines the cyclotron frequency of an ion in a magnetic field?

    <p>Charge-to-mass ratio</p> Signup and view all the answers

    What is the primary influence of the ionization technique used in mass spectrometry experiments?

    <p>Formation of species</p> Signup and view all the answers

    In Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry, what is the cyclotron frequency proportional to?

    <p>Magnetic field strength</p> Signup and view all the answers

    What characteristic distinguishes between even-electron and odd-electron species formed during ionization?

    <p>[M + H]+ or M+</p> Signup and view all the answers

    What does the cyclotron frequency of an ion depend on in Ion Cyclotron Resonance (ICR) mass spectrometry?

    <p>Ion charge</p> Signup and view all the answers

    Which rule involves the LEWIS and SENIOR check for element numbers in mass spectrometry?

    <p>Rule 2</p> Signup and view all the answers

    In the context of DBE equations for an organic molecule, which elements do not contribute when a valence of 2 is assumed?

    <p>Oxygen and Sulfur</p> Signup and view all the answers

    Which parameter is checked in Rule 5 of the 'Seven Golden Rules' in mass spectrometry?

    <p>Heteroatom ratio</p> Signup and view all the answers

    In the DBE equation for an organic molecule, what is the role of 'c', 'h', and 'n'?

    <p>Contributing elements</p> Signup and view all the answers

    Which publication provides information on advanced data analysis in mass spectrometry?

    <p>T. Kind, O. Fiehn, BMC Bioinformatics, 2007</p> Signup and view all the answers

    What is a crucial factor to consider when choosing solvents for ESI and APPI in sample preparation for mass spectrometry?

    <p>Solubility of the analyte</p> Signup and view all the answers

    What is the formula to calculate the Double Bond Equivalents (DBE) for an organic molecule?

    <p>$DBE = 1 + c - h/2 + n/2$</p> Signup and view all the answers

    Why is it not advisable to use the same sample solutions for both mass spectrometry and NMR?

    <p>NMR samples require higher concentrations</p> Signup and view all the answers

    What is one reason why analyte response may decrease with increases in the concentration of additives or contaminants?

    <p>Decreased ionization efficiency</p> Signup and view all the answers

    In sample preparation for ESI and APPI, what is the typical concentration range for mixtures?

    <p>~0.05 mg/mL</p> Signup and view all the answers

    Why is it often desirable to use isotopically labelled compounds when using internal standards in mass spectrometry?

    <p>To aid in quantitation or calibration</p> Signup and view all the answers

    What role does ECD FT-ICR MS demonstrate in polymer analysis for polyoxazoline species?

    <p>High mass accuracy method</p> Signup and view all the answers

    In the context of polyoxazoline species analysis, what does CRAM stand for?

    <p>Carboxylic-rich alicyclic molecules</p> Signup and view all the answers

    What does the KMD DBE vs. carbon number normalization method involve?

    <p>Addition of rings and double bonds</p> Signup and view all the answers

    What is the significance of the van Krevelen diagram in mass spectrometry?

    <p>Visualizing relative elemental compositions</p> Signup and view all the answers

    What does CH3F2 refer to in the context of mass spectrometry?

    <p>A unique chemical compound</p> Signup and view all the answers

    Which aspect is particularly enhanced when high mass accuracy methods are applied in tandem mass spectrometry for polymer analysis?

    <p>Structural characterization</p> Signup and view all the answers

    What advanced mass spectrometry technique was used for the analysis of methyl-initiated and xanthate-terminated poly(2-ethyl-2oxazoline) in the provided text?

    <p>Electron Capture Dissociation (ECD)</p> Signup and view all the answers

    What type of mass spectrometry was employed for the synthesis and analysis of the poly(2-ethyl-2oxazoline) polymer in the text?

    <p>Fourier Transform Mass Spectrometry (FTMS)</p> Signup and view all the answers

    Which technique was utilized to group fragments from the same fragmentation pathways together in the provided text?

    <p>Kendrick Mass Defect Plots</p> Signup and view all the answers

    What is the purpose of Kendrick mass defect (KMD) in mass spectrometry?

    <p>To normalize the mass scale to CH2 instead of 12C</p> Signup and view all the answers

    How does adding heteroatoms to a compound affect the Kendrick mass defect (KMD)?

    <p>It increases the KMD value</p> Signup and view all the answers

    In which type of species are half integer values observed in terms of double bond equivalents (DBE) in mass spectrometry?

    <p>Protonated or deprotonated species</p> Signup and view all the answers

    What role do alkyl chains play in changing the Kendrick mass defect (KMD) of a compound?

    <p>Alkyl chains have no impact on the KMD</p> Signup and view all the answers

    What is the main principle behind Kendrick mass defect (KMD) analysis as proposed by Kendrick in 1963?

    <p>To simplify and speed up data analysis by normalizing masses to CH2</p> Signup and view all the answers

    What characteristic makes radical ions distinct from other ion species in mass spectrometry?

    <p>They have an odd number of electrons</p> Signup and view all the answers

    Study Notes

    Introduction to Mass Spectrometry

    • Mass spectrometry analyzes samples (single compounds or mixtures) and measures mass-to-charge ratio (m/z) and mass
    • Requires gas-phase ions
    • Components of a mass spectrometer:
      • Sample inlet
      • Ionization method
      • Analyzer
      • Vacuum system
      • Detection
      • Data system

    Mass Spectrometry Basics

    • Mass-to-charge ratio (m/z) is calculated by: m/z = m/q, where m is the mass and q is the charge
    • 1 mass unit (u) is equal to 1/12 of the mass of a carbon-12 atom (12.000000 Da)
    • Isotopes have different masses due to varying numbers of neutrons

    Isotopes and Isotopologues

    • Isotopes are variants of an element with the same number of electrons and protons but different numbers of neutrons
    • Isotopologues are molecules with the same molecular formula but differing in isotope content
    • Examples of isotopes and isotopologues:
      • Carbon: 12C (98.9% natural abundance) and 13C (1.1% natural abundance)
      • Carbon monoxide (CO): 12C16O (98.9% 12C, 1.1% 13C) and 13C16O (1.1% 13C, 98.9% 12C)

    Resolving Power and Mass Accuracy

    • Resolving power is a figure of merit associated with measurement, typically measured in parts per million (ppm)
    • Better mass accuracy allows for higher confidence in assignment
    • Examples of resolving power:
      • TOF: 3-5 ppm
      • FTICR: ≤ 1 ppm

    Ionization Methods

    • Electron ionization (EI): typically operated at 70 eV
    • Soft ionization techniques:
      • Electrospray ionization (ESI)
      • Matrix-assisted laser desorption/ionization (MALDI)
    • Ionization energies: energy required to remove an electron from a molecule

    Analyzers

    • Sector instruments: use electric and magnetic fields to separate ions
    • Quadrupole instruments: use RF and DC fields to separate ions
    • Ion trap instruments: similar to quadrupoles, but ions are trapped and motion is damped
    • Time-of-flight (TOF) instruments: measure the time it takes for ions to travel a certain distance
    • Fourier transform ion cyclotron resonance (FTICR) instruments: use a strong magnetic field to trap ions and detect their motion
    • Orbitrap instruments: similar to FTICR, but with a different type of trap

    Tandem Mass Spectrometry

    • Intentional fragmentation used to obtain structural information

    • Commonly involves an "isolation" step to select an ion of interest

    • Methods of tandem mass spectrometry:

      • Collision-induced dissociation (CID)
      • Other methods: electron capture dissociation (ECD), electron detachment dissociation (EDD), etc.### Dissociation Mechanisms

    • Dissociation is affected by inductive effects, resonance effects, and product ion stability

    • Inductive effects: electron-donating groups (e.g., alkyl groups) stabilize, while electron-withdrawing groups (e.g., -NO2, -CN) destabilize

    • Resonance effects: electron-donating groups (e.g., alkyl groups) stabilize, while electron-withdrawing groups (e.g., -NO2, -CN) destabilize

    Carbocation Stability

    • More stable: CH3+ > CH3CH2+ > CH3CH2CH2+
    • Less stable: CH3CH2CH2+

    Common Observations

    • Aliphatic compounds: straight cleavages and rearrangements
    • Cyclic structures: straight cleavages and rearrangements
    • OH, C=O groups: loss of H2O
    • SO, CN groups: loss of H2S and HCN
    • Aromatic systems: difficult to fragment

    Rearrangements and Cyclisations

    • Often observed when using CID, loss of neutral molecule
    • Can lead to stable product ions
    • Examples: loss of H2O, CO, and HCN

    Photo-Dissociation

    • Ion absorbs photon(s) and dissociates
    • Energy of fragmentation is controlled by changing the photon's wavelength

    Mass Spectrometry

    • Influenced by ionization technique used (even-electron or odd-electron species)
    • Dissociation technique affects data interpretation
    • ms/ms (Tandem Mass Spectrometry) applicable to all tandem mass spectrometry techniques

    Interpretation of Data

    • Consider the experiment: ionization technique, dissociation technique, and data analysis
    • Data analysis: normalize to compositions other than CH2, using modified Kendrick mass defect

    Advanced Data Analysis

    • Double bond equivalents (DBE): C + Si - 1/2(H+F+Cl+Br+I) + 1/2(N+P) + 1
    • Simplified formula for organic molecules: DBE = 1 + c - h/2 + n/2

    Sample Preparation

    • MALDI: "Seven Golden Rules" for data analysis
    • ESI and APPI: concentration of liquid samples, choice of solvents, and use of internal standards

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    Description

    Test your knowledge on the basics of mass spectrometry as introduced by Dr. Mark P. Barrow in the Advanced Analytical Chemistry class. Contact information and resources provided. Topics include FT-ICR mass spectrometry for complex mixture analysis in various fields.

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