7.1.1 Principles of Mass Spectrometry

• Match the fragment with its $\frac{m}{z}$ value:


  Methyl ↔️ 15

  Ethyl ↔️ 29

  Hydroxyl ↔️ 17

  Carbonyl ↔️ 28
• If the molecular ion peak is at $\frac{m}{z} =$$72$, what is the molar mass of the molecule?


  72 g/mol
• The molecular ion peak is crucial for determining the molar mass of the compound.
• What is the purpose of mass spectrometry?

  Determine mass-to-charge ratio
• Each ion in mass spectrometry is characterized by its \frac{m}{z} value.
• The five main stages of mass spectrometry in the correct order

  1️⃣ Ionization

  2️⃣ Acceleration

  3️⃣ Deflection

  4️⃣ Detection

  5️⃣ Analysis
• In mass spectrometry, ionization converts molecules into ions.
• How does electron impact ionization work?

  High-energy electron bombardment
• Electrospray ionization is ideal for large biomolecules due to minimal fragmentation.
• Electron impact ionization produces extensive fragmentation patterns.
• What is a disadvantage of electrospray ionization?

  Requires a liquid sample
• Match the ionization technique with its fragmentation level:

  Electron Impact (EI) ↔️ Extensive

  Electrospray Ionization (ESI) ↔️ Minimal
• Mass spectrometry can be used to identify molecular mass and elucidate molecular structure.
• What accelerates ions in mass spectrometry?

  Electric field
• In mass spectrometry, ions are deflected according to their \frac{m}{z} ratio.
• The detection stage in mass spectrometry measures ion abundance.
• What is the equation for electron impact ionization?

  M + e^ - \rightarrow M^ + + 2e^ -</latex>
• What are the two main ionization techniques in mass spectrometry?

  EI and ESI
• Electron Impact (EI) uses high-energy electrons to bombard the sample, causing ionization and fragmentation
• Electron Impact (EI) provides strong fragmentation patterns useful for structural elucidation
• What type of ionization is ideal for large biomolecules?

  Electrospray Ionization (ESI)
• Electrospray Ionization (ESI) is a gentle ionization method that causes minimal fragmentation
• Electrospray Ionization (ESI) requires a liquid sample for ionization
• Outline the process of ion separation in mass spectrometry

  1️⃣ Ions are accelerated through an electric field

  2️⃣ Ions achieve uniform kinetic energy

  3️⃣ Ions pass through a magnetic field

  4️⃣ Ions deflect based on $\frac{m}{z}$

  5️⃣ Ions are detected individually at the detector
• What do detectors in mass spectrometry measure?

  Ion abundance
• Match the detector type with its principle of operation:

  Electron Multiplier ↔️ Incident ion releases electrons that are multiplied

  Faraday Cup ↔️ Converts ion charge into measurable current

  Microchannel Plate ↔️ Uses multiple channels to multiply signals
• Electron Multipliers in mass spectrometry are known for their high sensitivity and fast response
• In a mass spectrum, the abundance of ions is represented on the y-axis
• What does the molecular ion peak in a mass spectrum represent?

  Molar mass of the compound
• Fragment ions in a mass spectrum arise when the molecular ion breaks apart
• A significant peak at \frac{m}{z} = 57</latex> in a mass spectrum of a compound with $\frac{m}{z} =$$86$ indicates the loss of a $C_{2}H_{5}$ group
• What is the primary purpose of mass spectrometry?

  Determine $\frac{m}{z}$
• Describe the five main stages of mass spectrometry in order

  1️⃣ Ionization

  2️⃣ Acceleration

  3️⃣ Deflection

  4️⃣ Detection

  5️⃣ Analysis
• Match the stage of mass spectrometry with its function:

  Ionization ↔️ Converts molecules into ions

  Acceleration ↔️ Provides uniform kinetic energy

  Deflection ↔️ Separates ions by $\frac{m}{z}$

  Detection ↔️ Measures ion abundance
• The two main ionization techniques in mass spectrometry are Electron Impact (EI) and Electrospray Ionization (ESI)
• In ion separation, lighter ions with higher charge deflect more than heavier ions with lower charge
• What does the x-axis in a mass spectrum represent?

  $\frac{m}{z}$ ratio
• What does the y-axis of a mass spectrum represent?

  Relative abundance
• A mass spectrum is a graphical representation of the mass-to-charge ratios ($\frac{m}{z}$) of ions plotted against their relative abundances
• The molecular ion peak in a mass spectrum is used to determine the molar mass of a compound.