Mass Spectrophotometry Flashcards
• charged particles moving through a magnetic or an electrical field can be separated from other charged particles according to their mass-to-charge (m/z) ratios
Mass Spectrometry
• based on fragmentation and ionization of molecules using a suitable source of energy
Mass Spectrometry
Basic Components of MS
• Sample inlet
• Ionization source
• Mass analyzer
• Ion detector
Mass Spectrometry
Major steps:
• conversion of the parent molecule into a_____ (usually singly charged positive ions)
• acceleration of ions in a_______
• separation of the ions by______
• counting of the number of ions of each type or measurement of current produced when the ions strike a transducer
stream of ions
magnetic or electrical field
mass/charge ratio (m/z)
Mass Spectrometry
Two types:
• Quadrupole mass spectrometer
• Ion-trap mass spectrometer
• Only ions of specific mass/charge ratio can pass undeflected to the end of the rods, where they are detected
Quadrupole mass spectrometer
• direct electrical current and radiofrequency voltages of selected magnitudes are applied to two pairs of metallic rods
Quadrupole mass spectrometer
• ability to get full mass spectra at very low sample concentrations
Ion-trap mass spectrometer
• Three electrodes, in a ring shape and two end caps, produce ions in the cavity until selectively ejected to the ion detector
Ion-trap mass spectrometer
• used for greater selectivity and lower detection limits
• link three quadrupoles in series – triple quad
Tandem Mass Spectrometry
• GC/MS/MS and LC/MS/MS
• – used to scan across a preset m/z range and select an ion of interest
• – functions as a collision cell
• – serves to analyze the product ions generated in Q2 (full product ion scan or selected reaction monitoring)
Q1
Q2
Q3
