Triple quadrupole mass analyzer

A triple quadrupole instrument (QqQ) is a combination of two mass quadrupole mass filters (tandem mass spectrometry) separated by a collision cell which is also a quadrupole operating in RE-only mode (Pig. 1.18). A common nomencla- 

Depending on how the mass analyzers are operated, various types of MS and MS/MS experiments can be performed on a QqQ and these are summarized in Table 1.3. To normalize the description of various MS/MS or multi-stage MS experiments a symbolism has also been described [54, 55]. 

A product ion scan can obtain stmctural information of a given precursor ion while a precursor ion scan is more suited to find stmctural homologues in a complex mixture. Bosentan (Mr = 551, Fig. 1.19) has two metabolites corresponding to the tert-butyl hydroxylation product (Mr = 567) and the dealkylation of the me-thoxy group to form the phenol (Mr = 537). Bosentan (Tracker, Actelion Phrama-ceuticals) is an oral duel endothelin receptor antagonist approved for the use in arterial hypertension [56]. Selection of the fragment at m/z 280 can fish out precursor ions corresponding only to bosentan and these two metabolites (Fig. 1.19C). A similar result is obtained with the constant-neutral loss scan mode (Fig. 1.19D) which is based on neutral loss of 44 units. 

Full scan Ql/single ion monitoring (SIM) Ql Scan/fixed Rf mode 

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Different types of mass analyzers have been used for anthocyanin analysis single or triple quadrupole mass analyzers, TOP mass analyzer,ion trap mass analyzers,and the combination of analyzers cited above. " ... 

Figure 3.9 Conceptual view of tandem mass spectrometry with a tandem-inspace triple quadrupole mass analyzer." The first mass analyzer (Ql) selects the precursor ion of interest by allowing only it to pass, while discriminating against all others. The precursor ion is then fragmented, usually by energetic collisions, in the second quadrupole (q2) that is operated in transmissive mode allowing all fragment ions to be collimated and passed into the third quadrupole (Q3). Q3 performs mass analysis on the product ions that compose the tandem mass spectra and are rationalized to a structure.

Multiple mass analyzers exist that can perform tandem mass spectrometry. Some use a tandem-in-space configuration, such as the triple quadrupole mass analyzers illustrated (Fig.3.9). Others use a tandem-in-time configuration and include instruments such as ion-traps (ITMS) and Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS or FTMS). A triple quadrupole mass spectrometer can only perform the tandem process once for an isolated precursor ion (e.g., MS/MS), but trapping or tandem-in-time instruments can perform repetitive tandem mass spectrometry (MS ), thus adding n 1 degrees of structural characterization and elucidation. When an ion-trap is combined with HPLC and photodiode array detection, the net result is a profiling tool that is a powerful tool for both metabolite profiling and metabolite identification. 

The use of MALDI for the analysis of small molecules was recently reported. Particularly attractive is the coupling of a MALDI source with a triple quadrupole mass analyzer for quantitative analysis in the selected reaction monitoring (SRM) mode due to very high analysis speed. 

Fig. 8.10. Schematic illustration of a triple quadrupole mass analyzer with electrospray ion source.

ESI-LC/MS analysis Triple quadrupole mass analyzer API 2000 was used. The chromatographic separation was performed using Xbridge C18 MS column, a mobile phase composed of water, acetonitrile, and 0.01% formic acid in gradient conditions. The flow rate was 600 pL min. Twenty microliters of the studied solutions were injected on the column. 

Figure 1 Schematic drawing of an electrospray ionization (ESI) source and a triple-quadrupole mass analyzer. Ions are generated from the spray in the electrostatic field between the capillary and the counterelectrode. They are subsequently transmitted through a number of electrostatic lenses into the high-vacuum region of the first quadrupole mass analyzer (MS1). Optionally, ions selected by MSI can be fragmented by collision-induced dissociation (CIO) with gas (e.g., argon) in the collision cell and fragment ions analyzed in the second quadrupole mass analyzer (MS2). Representative residual pressures are indicated for the different regions of the instrument.

Nowadays, there is no validated LC—MS method for the quantitation of TTX. Testing different analytical columns and optimized LC—MS conditions are needed to separate and identify all TTXs in a sample. The main MS system for TTX detection uses atmospheric pressure ionization (API) in an electrospray ionization source (ESI) and collision-induced dissociation (CID) for identification using a triple quadrupole mass analyzer. For TTXs detection, the ESI interface uses the positive ionization mode. Thus, TTX exhibit a molecular mass of 320 Da. assignable to TTX - -H (C11H17N3O3 = 320). All its analogs are analyzed by LC—MS, in which positive ionization produces a t)q)ical molecular ion of [M - - H] for each compound. Table 15.4 shows the molecular formulas for TTX and several of its analogs detected in puffer fish and many other marine animals and their m/z for [M -f- H] ions. 

Shen DX, Lian HZ, Ding T et al (2009) Determination of low-level ink photoinitiator residues in packaged milk by solid-phase extraction and LC-ESI/MS/MS using triple-quadrupole mass analyzer. Anal Bioanal Chem 395(7) 2359-2370... 

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