Mass spectrometry is an application used to identify molecules within a sample by measuring the mass-to-charge ratio of ions. There are three components of mass spectroscopy: ionizing, analyzing, and detecting.
A sample is ionized and then ions are accelerated and sent through an electric and magnetic field, which affects speed and trajectory. The magnitude at which an ion changes trajectory depends on the mass-to-charge ratio. Ions with the same ratio will be deflected in the same amount.
The differences in mass-to-charge ratio allows a mass analyzer to sort the ions, and results are displayed as spectra of the relative abundance of the detected ions, based on the mass-to-charge ratio. Components of the sample are identified by correlating known masses of substances to the masses identified in the sample or through fragmentation pattern.
Lasers are used in two different ways in mass spectrometry. They are used to vaporize the sample and to ionize it.
Two-step laser mass spectrometry (L2MS) requires two steps using two different laser pulses. In the first step, a pulsed infrared laser is focused on the sample to cause rapid heating and desorption of molecules in the sample. In the second step, a pulse ultraviolet laser causes ionization of the desorbed molecules. The molecules are then analyzed. In this method, desorption and ionization are independently tunable. This allows trace amounts of organic molecules to be detected in complex materials.
Matrix-assisted laser desorption ionization (MALDI) uses one step and one laser pulse to both vaporize and ionize the sample. Before starting, the sample is mixed into a laser energy absorbing matrix material. A pulsed laser triggers ablation and desorption of the sample and the matrix material. Molecules are ionized in the hot plume of ablated gases and then analyzed.
Contact us for assistance in selecting the appropriate system for your mass spectrometry application.