Mass spectrometry can determine the properties of atoms and molecules.
Mass spectrometers are instruments that measure the masses and relative concentrations of atoms and molecules, making use of the basic magnetic force on a moving charged particle. Mass spectrometers employ dynamic, magnetic or electric fields in conjunction with two or more mass analyzers for tandem mass spectrometry. They can be specialized, combining the features of different analyzers for specific types of mass analysis.
FT-ICR Mass Spectrometer
FT-ICR (Fourier transform ion cyclotron resonance) mass spectrometers are useful, high-precision analyzers. Fourier transform mass spectrometry (FTMS) detects the image current produced by ions cyclotroning in the presence of a magnetic field. The ions are injected into a static electric/magnetic ion trap, where they form part of a circuit. Detectors in the system measure the electrical signal of ions that pass near them, producing a periodic signal. The frequency of the signal can be used determine the ion's mass/charge ratio. The FTMS is highly sensitive and boasts higher precision and resolution than other methods.
Sector Field Analyzer
Sector field mass analyzers use either an electric or magnetic field to affect charged particles. These analyzers alter the trajectories of charged particles according to their mass and charge, and they deflect lighter, more charged and faster-moving ions in the process. Sector analyzers scan a narrow range of mass/charge ratios to catalog the ions present.
Time-of-flight Analyzer
Time-of-flight (TOF) analyzers use an electric field to accelerate ions and then measure the time it takes for them to reach a detector. If all particles have the same charge, their speed will vary only according to their masses, and the lighter ions will reach the detector first. Their mass can then be measured by their time of flight.
Quadrupole Analyzers and Ion Traps
Quadrupole analyzers selectively stabilize or destabilize the paths of ions using oscillating electrical fields. By passing ions through a radio frequency quadrupole field, single mass/charge ratios can be measured. The frequency with which mass/charge ratios are measured can be increased through changes made to the potentials on magnetic lenses. In the related quadrupole ion trap, the same physical principals are employed, but the ions are trapped and ejected sequentially. A linear quadrupole ion trap narrows the quadrupole field, from a full three dimensions down to two, and then makes use of the same methods to trap and eject ions.
Tags: mass charge, charge ratios, mass charge ratios, according their, atoms molecules, charge ratios measured, charged particles
