Triple quadrupole mass spectrometers range

Fig. 2. Schematics of an electrospray triple quadrupole mass spectrometer. A mass spectrum is acquired by scanning the first quadrupole Qi over the desired mass range. For a fragment spectrum the first quadrupole is fixed at a given m/z value transmitting only ions of this m/z value into the gas-filled collision zone. The fragments are extracted and their mass determined by the scanning third quadrupole Q3. For a precursor ion scan the third quadrupole is fixed at the mass of a specific fragment ion (e.g., a phosphate ion) and the second is scanning over the mass range.

Triple quadrupole mass spectrometers, QqQ, have almost become a standard analytical tool for LC-MS/MS applications, in particular when accurate quantitation is desired (Chap. 12). Ever since their introduction [124-126] they have continuously been improved in terms of mass range, resolution, and sensitivity (Fig. 4.38). [127-129]... 

The MALDI triple-quadrupole mass spectrometer generates calibration curves with linearity and dynamic ranges similar to those typically expected from a triple-quadrupole mass spectrometer. In most cases, linearity is established over three orders of magnitude with suitable accuracy and precision. Figure 11.5 depicts calibration curves obtained for some common drugs using neat standards. 

For abbreviation of analyte names see Sect. Abbreviations . ACN acetonitrile, APCI atmospheric pressure chemical ionization, dial, microdialysis samples, ESI electrospray ionization, FA formic acid, iso isocratic, IT ion trap, lin range linear range, MeOH methanol, MRM multiple reaction monitoring, MS full scan mass spectrometry, n.s. not specified, OAc acetate, QqQ triple quadrupole mass spectrometer, SIM selected ion monitoring, Solv HPLC solvent, SQ single quadrupole mass spectrometer, T temperature Ratios given as v/v... 

Mass spectrometry Positive ion electrospray ionization mass spectrometry (ESl-MS) analysis was performed on a PE API 2000 triple quadrupole mass spectrometer (Sciex, Toronto, Canada). Spray voltage was set to 4.8 kV, and 30 V orifice voltage was applied. Samples were dissolved in a methanol-water (1 1, v/v) mixture containing 0.1% acetic acid, and 5 pL of sample was injected with a flow rate of 100 pL/min. The instmment was used in a Qj scan mode in the range of m/z 400-1700, with a step size of 0.3 amu and a dwell time of 0.5 ms. Other chimeric peptides in this study were purified and characterized in the same or a very similar way. 

Mass Spectrometry and Other Analytical Procedures. Liquid chromatography electrospray mass spectrometry (LC-ESMS) was performed on approximately 1 pg protein samples with a Perkin Elmer Sciex API-300 triple quadrupole mass spectrometer fitted with an articulated ion spray source and set to scan over a range of 400-3000... 

Liquid chromatography-mass spectrometry (LC-ESI-MS) was performed on a PE-Sciex API-Ill triple quadrupole mass spectrometer with an lonSpray source. The samples were separated on the Nucleosil Cl 8 column with gradient 1 a splitting device was used to direct a portion of the effluent into the mass spectrometer. Data were acquired in the range of m/z 400-1000, with sufficient resolution to detect the isotope peaks for singly-charged ions at m/z 1000. 

Tandem MS. The thermospray HPLC/MS/MS was performed on a Finnigan MAT TSQ-46C triple quadrupole mass spectrometer interfaced to an INCOS Data System (Finnigan MAT, San Jose, CA). The triple quadrupole was operated with the first and second quadrupoles in the RF mode during HPLC/MS operation. For HPLC/MS/MS analysis, the first quadrupole selected the [M+H] ion of the compound, while the third quadrupole was scanned over the mass range of 12-300 daltons. The second quadrupole serves as a collision chamber. Argon collision gas was added to the enclosed chamber of this quadrupole to give a pressure of 2 mtorr for collisional activation of the sample ions. 

While a typical standard curve for a discovery PK study would still be in the 1-10,000 ng/mL range, it is becoming more likely that one would need an assay in the 0.1-1000 ng/mL range. The reason is that test compounds are becoming more potent so that lower doses are being given (in some cases) to test animals in various efficacy assays. As stated above, this has not been an issue for the bioanalytical community because the triple quadrupole mass spectrometers have become more sensitive. 

Increasing the resolution decreases the number of ions that reach the detector. Good resolution also depends on the quality of the machining for the quadrupole rods. Quadrupole rods can have other functions besides their use as a mass filter. An RF-only quadmpole will act as an ion guide for ions within a broad mass range. For example, the collision region of a triple quadrupole mass spectrometer uses an RF ion guide. A DC-only quadrupole is used as a lens element in some ion optical systems. 

The uptake of HRMS instrumentation into metabolite identification laboratories points to future developments and uses for these types of mass analyzers. From a hardware perspective, developments in TOF and Orbitrap technology will be needed to address lingering issues specific to these analyzers. In the TOF area, current commercial systems just coming to the market have addressed historical limitations of resolution, dynamic range, and mass accuracy. It remains to be seen if these specifications are sufficient or if further gains are needed. These instruments are not yet as sensitive as high-end triple quadrupole mass spectrometers, and improvements are needed in this area. For Orbitrap-based systems, the main limitations are scan speed and sensitivity. As... 

Figure 4.7 Two-dimensional mass spectrometric analysis of polyunsaturated fatty acid fragmentation pattern with variation of collision-gas pressure. MS analysis was performed with a TSQ Quantum Ultra Plus triple-quadrupole mass spectrometer (Thermo Fisher Scientific, San Jose, CA) equipped with an automated nanospray apparatus (i.e.. Nanomate HD, Advion Bioscience Ltd., Ithaca, NY) and Xcalibur system software. Product-ion scan of 8,11,14-eicosatrienoic acid (20 3 FA) (5 pmol/pL) was performed after direct infusion in the negative-ion mode at the fixed collision energy of 16 eV and varied collision-gas pressures ranging from 0 to 3 mTorr as indicated. A 2-min period of signal averaging in the profile mode was employed for each scan. All the scans were automatically acquired with a customized sequence subroutine operated under Xcalibur software. All the scans are displayed after being amplified to the 5% of the base peak in each individual scan.

Tandem mass spectrometers are either triple quadrupole systems (the collision cell is also a quadrupole) or quadrupole ion-trap spectrometers. A triple quadrupole mass spectrometry system is shown in Figure 32F-2. Here, the first quadrupole acts as a mass filter to select the ion of interest. This ion is then fragmented by collision with an inert gas in the collision cell. The final quadrupole mass analyzes the fragments produced. The triple quadrupole system can be operated in other modes. For example, if the first quadrupole is operated as a wide mass filter to transmit a wide range of ions and no collision gas is present in the collision cell, the instrument is operating as an LC/MS system. The instrument can be operated by scanning one or both quadrupoles to produce mass spectra of the fragments of ions selected by the first quadrupole as that quadrupole is scanned. 

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