Mass Spec Analyzer
Mass Spectrometry (MS) is a technique for separating ions by their mass-to-charge (m/z) ratios. It allows the detection of compounds by separating ions by their unique mass. It can be divided into two broad applications:
1. identification of compounds by mass of one or more elements in a compound
2. determination of isotopic composition of one or more elements in a compound
A Mass Spectrometer is a device used for mass spectrometry, and produces a mass spectrum of a sample to find its composition. This is normally achieved by ionizing the sample and separating ions of differing masses and recording their relative abundance by measuring intensities of ion flux. A typical mass spectrometer comprises three parts: an ion source, a mass analyzer, and a detector.
The mass analyzer is the most flexible part of the mass spectrometer. It uses an electric or magnetic field to deflect the charged particles, while the Kinetic energy imparted by motion through an electric field gives the particles inertia dependent on their mass. Thus, the analyzer steers the particles to the detector, based on their mass-to-charge ratios (m/z) by varying an electric or magnetic field. The smallest, most highly charged ions move most rapidly. It can be used to select a narrow range of m/z's or to scan through a range of m/z's to catalog the ions present. Besides the original magnetic-sector types, several types are currently in more common use, including time-of-flight, ion trap, and quadrupole mass analyzers.
Various kinds of mass analyzers have been produced. Perhaps the easiest to understand is the Time-of-flight (TOF) analyzer, typically integrated with MALDI ion sources. It boosts ions to the same Kinetic energy by passage through an electric field, and the times they take to reach the detector are measured. Quadrupoles and quadrupole ion traps use electrical fields to selectively stabilize or destabilize ions falling within a narrow window of m/z values. Sector instruments change the direction ions are flying through the mass analyzer. Fourier Transform Mass Spectrometry measures mass by detecting the image current produced by ions spinning (cyclotron) in the presence of a magnetic field. This technique provides extremely high resolution and mass measurement accuracy. The best mass analyzer for an experiment depends upon the type of information to be gleaned from the experiment.