Fast atom bombardment source design

Several other interface designs were introduced over this period, including continuous flow fast atom bombardment (CFFAB)" and the particle beam interface (PBI)," but it was not until the introduction of the API source that LC/MS applications really came to the forefront for quantitative analysis. Early work by Muck and Henion proved the utility of an atmospheric pressure interface using a tandem quadrupole mass spectrometer. 

A LMI emitter s smallness makes it possible to attach it to the ion source of almost any magnetic sector or quadrupole mass spectrometer. Ion sources which have already been designed for fast atom bombardment (FAB) or field desorption (FD) are ideally suited to modification for LMI/SIMS operation. 

The basic function of the mass spectrometer is to measure the mass-to-charge ratios of analyte ions, and the various designs of mass spectrometers have been described in detail in the literature. The HPLC-MS system has four main components consisting of a sample inlet, an ion source, a mass analyzer, and finally an ion detector. The sample introduction system vaporizes the HPLC column effluent. The ion source produces ions from the neutral analyte molecules in the vapor phase. Several designs of ion sources have been used over the past years including electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), thermospray ionization (TSP), continuous flow fast atom bombardment (FAB), and atmospheric pressure photoionization (APPI). The inductively coupled plasma (ICP) is a hard ionization source and is used specifically for the detection of metals and metals in adducts or in organometallic compounds. Generally, ICP-MS is used for elemental speciation analysis with HPLC, which has been described elsewhere in... 

TOF-TOF Instruments. A simple design for a tandem (TOF-TOF) instrument that incorporates two drift regions separated by a collision chamber has been reported by Jardine et al. As shown in Figure 9.5, the instrument uses fast-atom bombardment ionization. Because this is a continuous ionization technique, a deflection gating system is used to define the initial ion packet, while a second set of deflectors (located close to the collison chamber) is used for mass selection. In addition, the collision cell is raised to a voltage that is intermediate between ground and the source potential, so that product ions will be reaccelerated and will have velocities different from their precursors. 

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