Cylindrical ion trap, CIT

Riter et al. applied Membrane Inlet Mass Spectrometry (MIMS) coupled to a miniature mass spectrometer equipped with a cylindrical ion trap (CIT) analyzer to monitor the flavor components directly from human breath [6], Johnson et al. measured ethanol concentrations on-line in fermentation broths from a 9000-L fermentation reactor for a period of four days [7], However, data reported in the above papers referred to experiments lasting no more than a few days. 

A cylindrical ion trap, CIT, configured as the inscribed cylinder to a 3D quadrupole ion trap is shown in Figure 6. A CIT can be fabricated readily from a polished metal cylinder with an internal radius of a few millimeters and two disks perforated for admission of electrons or ions and for ejection of ions. 

In 2004, the Cooks group at Purdue built a rectilinear-LQIT (RLQIT) with rectangular electrodes, and they previously built cylindrical ion traps (CIT). Both of these traps are attractive alternatives to XQITs that use hyperbolic electrodes because they are easier to build. 

Miniature cylindrical ion traps (mini-CITs) A mini-CIT is defined according to the radius, r, of the ring or barrel electrode when rc is <5 mm, the CIT is classed as miniature. Mass analysis using the... 

Figure 7 A schematic representation of the ion source, ion optics, CiT, and detector. The filament, mounting hardware, and gate eiectrode are based on those used in the Finnigan ITS-40-instrument. (Reproduced with permission from Patterson GE, Guymon /U, Riter LS, eta/. (2002) Miniature cylindrical ion trap mass spectrometer. Analytical Chemistry 74 6145-6153. Copyright (2002) American Chemical Society.)...

Figure 10 A schematic represerttation of two of the four parallel analysis channels in the 2 x 2 array of mini-CITs. (Reproduced with permission from Tabert AM, Griep-Raming J, Guymon AJ, and Cooks RG (2003) High-throughput miniature cylindrical ion trap array mass, spectrometer. Analytical Chemistry 75 5656-5664. Copyright 2003, by American Chemical Society.)...

Miniature cylindrical ion trap array An approach to the rapid screening of large numbers of samples in the areas of proteomics, industrial process monitoring, and metabolomics is to use a multiplexed inlet system with a multiplexed mass spectrometer having an equal number of parallel sample channels. To this end, a high-throughput mini-CIT array mass spectrometer has been developed and tested. 

The cylindrical device is easier to construct than a 3D ion trap having hyperbolic electrodes, and variation of the ratio rc 2zc (radius of cylinder to height of CIT) is facile. Research into QTs has focused upon small CITs, described as mini-CITs, for application as tandem mass spectrometers and for the development of arrays of mini-CITs. In order to achieve in a mini-CIT a given value of z(= qx from eqn [2]), an elevated drive frequency is required to compensate for the reduced value of r. In this manner, a potential well of sufficient magnitude is facilitated that permits excitation of ions confined within the mini-CIT. 

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