Quadrupole Fourier transform mass spectrometers

Figure 2.17 Quadrupole Fourier transform mass spectrometer (FTMS). Reprinted with permission from Ref [8]. 2003 American Chemical Society.

The detector in capillary electrophoresis is the main component in nanoanalyses. Many detectors can be used for this purpose but the mass spectrometer is the best one due to its wide ranges and low concentration detection capabilities. In the last few years, time-of-flight-mass spectrometry (TOF-MS) instruments have come onto the market and are available in many sizes, but small instruments are preferred in NCE. Bruker (Billerica, MA) has provided a micro-TOF-MS-LC (2x2x4 feet) system for nanoanalyses. Bruker also introduced a Q-q-FTMS (Fourier transform mass spectrometer) for proteomics called the APEX-QE. It offers fast, dual quadrupoles, which provides the first stages followed by FTMS for the highest mass accuracy. It can be coupled to NCE and controlled by Bmker s ProteinScape work flow and warehousing... 

A number of mass analyzers in use today have been coupled to these sources. These include two- and three-dimensional quadrupole field, time-of-flight (TOF), quadrupole-TOF hybrids, magnetic sector, and Fourier transform mass spectrometers. Paramount to the mass spectrometer analyzer used in the analysis is proper sample preparation. With proper preparation of proteins and peptides, their molecular weights can be determined with high mass accuracy. Conversely, a poorly prepared sample will lead to poor or no mass spectrometer results. For peptides and proteins, the mass accuracy is typically better than 0.01%. 

Along with advances in various ionization sources, significant improvements have been made in the area of mass analyzers. Mass analyzers can be differentiated based on several attributes such as scan speed, duty cycle, mass resolution, mass range, and cost [126], The most common analyzers used for metabonomics analyses include the quadrupole and TOF-based analyzers [125-127], Some other analyzers that have been reported for use in MS-based metabonomics analyses are the ion traps, Orbitraps, and Fourier transform mass spectrometers [128,129],... 

Other Mass Analyzers. Other analyzers, such as quadrupole ion trap (QIP) and Fourier transform mass spectrometer (FTMS), are of some interest for proteomics. The quadrupole ion trap mass analyzer was devised by Wolfgang Paul it works on the principle of trapping ions with a particular RF in the quadrupole mass analyzer. This device provides a way to eject ions of certain radio frequency and retain the others, only the latter are allowed to reach the detector by scanning ions of a particular radio frequency. In this method, the selected ions can be subjected to fragmentation by collision-induced dissociation (CID), which is useful for the analysis of peptides. 

Mclver TT Jr, Hunter RL, Bowers WD. Coupling a quadrupole mass-spectrometer and a fourier-transform mass-spectrometer. Int J Mass Spectrom Ion Proc. 1985 64 67 77. 

In environmental analysis, there has been increasing use of TOF, quadrupole. ion-trap, and Fourier transform mass spectrometers in addition to desorption ionization methods such as MALDI. Detection and quantitative determination of such widely diverse contaminants as perfluoroorganics, polybromi-nated diphenyl ethers, pharmaceuticals, byproducts of water disinfection, pesticides, algal toxins, surfactants, methyl-t-butyl ether, arsenic, and various microorgan-i.sms are now carried out using mass spectrometric methods. Mass spectrometry is also used to determine compounds of interest in homeland security. ... 

Laser-microprobe mass spectrometers are used for the study of solid surfaces. Ablation of the surface is accomplished with a high-power, pulsed laser, usually a Nd-YAG laser. After frequency quadrupling, theNd-YAG laser can produce 266-nm radiation focused to a spot as small as 0.5 pm. The power density of the radiation within this spot can be as high as 10to 10" W/cm. On ablation of the surface a small fraction of the atoms are ionized. The ions produced are accel crated and then analyzed, usually by tlme-of-flight mass spectrometry. In some cases laser microprobes have been combined with quadrupole ion traps and with Fourier transform mass spectrometers. Laser-microprobe tandem mass spectrometry is also receiv-... 

For other instruments, the laser timing accuracy is not nearly so critical. For quadrupole and sector instruments, where the detection is essentially continuous, the laser is usually set to fire as fast as possible. For ion traps and Fourier transform mass spectrometers the accuracy needs to be controlled to within a few microseconds or milliseconds, depending on the arrangement. This can usually be achieved by letting the mass spectrometer send a trigger to the laser, which will then hre and emit its laser pulse a few hundred nanoseconds later. The jitter in this timing can be tens of nanoseconds, but it is sufficiently low for the instruments involved. 

Once ions are produced, they are typically directed into a mass analyzer, where the ions are separated by their mass-charge ratios and detected. The types of mass analyzers vary widely.By far, the most common is the time-of-flight mass analyzer due to its simplicity and the pulsed nature of ion extraction from the ion source, which makes it especially compatible with pulsed laser excitation, but laser desorption/ionization sources have been coupled to quadrupoles, electromagnetic sector instruments, orthogonal time-of-flight mass spectrometers, quadmpole ion traps, Fourier transform mass spectrometers, and even the recently introduced Orbitrap. Detailed discussion of these mass analyzers is beyond the scope of this chapter but is not out of the scope of other chapters in this volume and elsewhere. However, laser desorption ion sources produce ions with a particular momentum and temperamre, and great care must be taken in coupling these ion sources to the mass spectrometers so that the ions momentum and temperature parameters are compatible with the instrument at hand. 

We discussed the fundamentals of mass spectrometry in Chapter 10 and infrared spectrometry in Chapter 8. The quadrupole mass spectrometer and the Fourier transform infrared spectrometer have been adapted to and used with GC equipment as detectors with great success. Gas chromatography-mass spectrometry (GC-MS) and gas chromatography-infrared spectrometry (GC-IR) are very powerful tools for qualitative analysis in GC because not only do they give retention time information, but, due to their inherent speed, they are also able to measure and record the mass spectrum or infrared (IR) spectrum of the individual sample components as they elute from the GC column. It is like taking a photograph of each component as it elutes. See Figure 12.14. Coupled with the computer banks of mass and IR spectra, a component s identity is an easy chore for such a detector. It seems the only real... 

The experiments were performed in two different ultra high vacuum (UHV) chambers using two different Pt(lll) single crystals. The X-ray photoelectron spectra were obtained in a chamber with a base pressure of lxlO" Torr. The system has been described in detail elsewhere. In brief, the UHV chamber is equipped with low energy electron diffraction (LEED), an X-ray photoelectron spectrometer (XPS), a quadrupole mass spectrometer (QMS) for temperature programmed desorption (TPD), and a Fourier transform infrared spectrometer (FTIR) for reflection absorption infrared spectroscopy (RAIRS). All RAIRS and TPD experiments were performed in a second chamber with a base pressure of 2 X 10 ° Torr. The system has been described in detail elsewhere. In brief, the UHV chamber is equipped for LEED, Auger electron spectroscopy (AES) and TPD experiments with a QMS. The chamber is coupled to a commercial FTIR spectrometer, a Bruker IFS 66v/S. To achieve maximum sensitivity, an... 

Fig. 1.5. Experimental setup of the high-frequency laser vaporization cluster ion source driven by a 100-Hz Nd Yag laser for the production of ion clusters, ion optics with a quadrupole deflector, and quadrupole mass Alter for size-selection and deposition the analysis chamber with a mass spectrometer for thermal desorption spectroscopy (TDS), a Fourier transform infrared spectrometer, a spherical electron energy analyzer for Auger electron spectroscopy (AES) for in situ characterization of the clusters [73]...

Once the polymer molecules have been transferred to the gas phase as ions, they are separated on the basis of their mass-to-charge ratio. Mass spectrometers nsed for MALDI analysis may differ, but for those that are commercially available, separation is effected by TOE Other methods such as quadrupole filter and Fourier transform mass spectrometry (FTMS) may also be used. 

Hendrickson, C.L. Quinn, J.P. Emmett, M.R. Marshall, A.G. Mass-selective external ion accumulation for Fourier transform ion cyclotron resonance mass spectrometry. 49th ASMS Conference on Mass Spectrometry and Allied Topics. May 27-31, 2001. Chicago, IL. Patrie, S.M. Charlebois, J.P. Whipple, D. Kelleher, N.L. Hendrickson, C.L. Quinn, J.P. Marshall, A.G. Mukhopadhyay, B. Construction of a hybrid quadrupole/Fourier transform ion cyclotron resonance mass spectrometer for versatile MS/MS above 10 kDa J. Am. Soc. Mass Spectrom. 2004, 75(7), 1099-1108. 

Cl. A. Brock, D. M. Horn, E. C. Peters, C. M. Shaw, C. Eiricson, Q. T. Fung, and A. R. Salomon, An automated matrix-assisted laser desorption/ionization quadrupole-Fourier-transform ion cyclotron resonance mass spectrometer. Anal. Chem. 75, 3419-3428 (2003). 

ETD induces a less-exothermic (i.e., more gentle ) electron-transfer reaction than ECD and its process is non-ergodic. ETD ean be performed in quadrupole ion trap mass spectrometers, whieh are widely available to the mass spectrometry eommu-nity. Several types of mass spectrometers have been configured to perform ETD experiments [59,60]. These include a hybrid ion trap (3D, a hnear multipole, or ring guide)-Fourier transform ion cyclotron resonance mass spectrometer (LTQ-FT), hybrid triple qrradrupole-linear ion trap irrstmment (QqQ-LIT), and hybrid qrradrupole time of flight (QTOF). 

Patrie SM, Charlebois JP, Whipple D, KelleherNL, Hendrickson CL, Quitm JP, Marshall AG, Mukhopadhyay B. Construction of a hybrid quadrupole Fourier transform ion cy-elotron resonance mass spectrometer for versatile MS MS above 10 kDa. J Am Soc Mass Spectrom. 2004 15 1099 108. 

Discuss the differences between quadrupole ion-trap mass spectrometers and Fourier transform ICR mass spectrometers. 

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