Quadrupole FTICR analyzer

In terms of mass spectrometry instrumentation, the currently available instruments such as time-of-flight (TOF) analyzers and hybrid quadrupole-TOF analyzers are able to acquire complete mass spectra at rates compatible with fast CE separations. As CE or ultrafast chromatography replaces conventional, slow HPEC applications, TOF-based mass spectrometers will be needed to replace the less efficient scanning types of instruments such as quadrupoles and ion traps for most high-throughput applications. FTICR mass spectrometry remains unsurpassed in terms of resolution and mass accuracy for both MS and MS-MS applications. However, the throughput of FTICR mass spectrometric... 

Different mass analysers can be combined with the electrospray ionization source to effect analysis. These include magnetic sector analysers, quadrupole filter (Q), quadrupole ion trap (QIT), time of flight (TOF), and more recently the Fourrier transform ion cyclotron resonance (FTICR) mass analysers. Tandem mass spectrometry can also be effected by combining one or more mass analysers in tandem, as in a triple quadrupole or a QTOF. The first analyzer is usually used as a mass filter to select parent ions that can be fragmented and analyzed by subsequent analysers. 

Mass analyzers interrogate and resolve ions produced by an ion source based on their m/z ratios. Several types of mass analyzers are utilized for proteomic analysis including time-of-flight (TOF) quadrupoles, ion traps, and Fourier transform ion cyclotron resonance (FTICR). Mass analyzers may be assembled in hybrid configurations. MS instruments such as quadrupole TOF and quadra-pole ion trap-FTICR facilitate diversified applications and achieved great success. 

For MS detection, the microfluidic chip has been coupled to various ionization interfaces (ESI, MALDI) and to different mass analyzers (by single quadrupole, triple Q, ion-trap, MS/MS, and FTICR). The chip can be single- or multi-channel, and can be integrated with various sample handling processes such as preconcentration, digestion, and separation. The following two sections describe the two ionization interfaces (ESI and MALDI) that precede the MS analysis. 

Recent innovations in mass spectrometry have provided incorporation of two, three, and four analyzers into commercially available tandem instruments. In addition, different mass analyzers may be combined to form a hybrid mass spectrometer such as the quadrupole-TOF (Q-TOF). Various types of tandem mass spectrometers include the quadruopole-TOF, time-of-flight-time-of-hight (TOF-TOF), triple-quadrupole, and Orbitrap-FTICR configurations. 

Relatively new mass analyzers with very high resolution include the quadrupole ion trap (QIT) and the Fourier-transform ion cyclotron resonance (FTICR) instruments. In both analyzers, ions are trapped in a 3D field, and are analyzed once trapped. In Table 15.3, the mass analyzers described here are compared. The combination of MS with other analytical techniques is also very common MS has been widely used following chromatographic separations, for mass analysis. 

Commercial LITs were introduced in 2002 as either a stand-alone mass spectrometer (LTQ) [318] or as part of a triple quadrupole (Q-Trap) [319] or in 2005 as part of hybrid tandem mass spectrometers (LTQ-Orbitrap and LTQ-FTICR) [88,90], Application of LTQ-FTICR for metabolism studies has been reviewed by Shipkova et al. [90], In comparison to other mass analyzer types, FTICR-based mass spectrometers are not very popular for metabolite identification studies due to availability of less expensive and more user-friendly LTQ-Orbitrap and Q-TOF-based systems. Another limitation associated with the FTICR-based hybrid mass spectrometers is the TOF effect, which results in efficient trapping of only the high-mass ions [90],... 

A variety of mass analyzers have been used in MSI experiments such as TOP, quadrupole ion trap (QIT), linear ion trap (LIT), QqQ, Fourier transform ion cyclotron resonance (FTICR), and Orbitrap. Also, various tandem configurations of these mass analyzers such as QqTOF, QqLIT, and TOF/TOF have been used. Due to the many possible interferenees from endogenous compounds or from the matrix, the use of tandem mass speetrometry (MS/MS or MS") or the ability to perform high-resolution and aeeurate mass measurements for the analysis of drugs by MALDI is essential. An overview of some of the established instrumentation and their respeetive eapabilities is presented below. 

Some ionization techniques (El, FAB, and SIMS) are compatible with all mass analyzers. PD, LD, and MALDI are most suited to TOF analyses. Atmospheric pressure ionization methods (TSP, ESI, APCI) are best coupled with quadrupole and ion trap instruments. Sector and FTICR instruments can also operate with chromatographic interfaces however, a significant reduction of pressure in the system is required. Consequently, in FTICR, the ion source and the ICR cells must be separated by a distance of about 1 m. Powerful ion optics is required for the transmission of ions for these long distances. This inconvenience, however, is offset by the advantages of FTICR, such as extremely high resolution and the ability to store the ions of interest for long periods. 

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