Quadmpole mass spectrometer

Quadmpole mass spectrometers (mass filters) allow ions at each m/z value to pass through the analyzer sequentially. For example, ions at m/z 100, 101, and 102 are allowed to pass one after the other through the quadmpole assembly so that first m/z 100 is transmitted, then m/z 101, then m/z 102, and so on. Therefore, the ion collector at the end of the quadmpole unit needs to cover only one point or focus in space and can be placed immediately behind the analyzer (Figure 30.1). A complete mass spectram is recorded over a period of time (temporally), which is set by the voltages on the quadmpole analyzer. In this mode of operation, the ions are said to be scanned sequentially. The resolution of m/z values is dependent solely on the analyzer and not on the detector. The single-point collector is discussed in detail in Chapter 28. 

Like sector analyzers, quadrupole analyzers are well suited for continuous ion sources such as ESI, but are not well-suited for pulsed ionization methods. Quadmpole mass spectrometers are generally substantially cheaper and smaller than sector instruments and Qq-TOFs. They are very often used in combination with GC and LC, and single or triple quadmpole mass filters are very common benchtop instruments for routine measurements. 

Fig. 4.38. Schematic of a triple quadmpole mass spectrometer. Reproduced from Ref. [125] with permission. Elsevier Science, 1979. 

Finnigan, R. E. Quadmpole mass spectrometers. Anal. Chem. 1994, 66, 969A-975A. 

Xu, X., Veals, J., and Korfmacher, W. A. (2003). Comparison of conventional and enhanced mass resolution triple-quadmpole mass spectrometers for discovery bioanalytical applications. Rapid Commun. Mass Spectrom. 17 832-837. 

Yang, L., Amad, M., Winnik, W. M., Schoen, A. E., Schweingruber, H., Mylchreest, I., and Rudewicz, P. J. (2002). Investigation of an enhanced resolution triple quadmpole mass spectrometer for high-throughput liquid chromatography/tandem mass spectrometry assays. Rapid Commun. Mass Spectrom. 16 2060-2066. 

Increasing the resolution also allows the separation and differentiation of endogenous compounds in biological matrices from a drug of interest or its metabolites. A comparison of mass spectra of sulfacetamide obtained using a quadmpole mass spectrometer (unit mass resolution) with that obtained using a time-of-flight mass spectrometer (R = 10,000) is shown in Fig. 4.9. While at unit mass resolution the... 

Until most recently, GSH assay involving neutral loss of 129 has mostly been carried out using triple-quadmpole mass spectrometers operated under nominal mass conditions. This approach suffers from low sensitivity because both... 

Figure 9.3. LC-APCI-MS spectra of DL, 6-OH-DL, 3-OH-DL, N-OH-DL, and 1-pyridine-U-oxide-DL generated using a TSQ Quantum triple-quadmpole mass spectrometer. Vaporizer...

A number of factors have contributed to renewed interest in DI techniques for quantitative analysis. Since the reasonable throughput in routine use of the LC-ESI-triple-quadmpole mass spectrometer seems to have peaked at about 3-4 samples per minute, there is renewed interest in finding alternate ways to improve quantitative throughput. Recent developments in DI mass spectrometry (DIMS) have realistically made routine small-molecule quantification feasible. This chapter will briefly outline the issues encountered when quantifying drug molecules by DIMS. The latest developments will be described in relation to historical problems... 

Determination of MS/MS conditions using the MALDI ion source coupled to the triple-quadrupole mass spectrometer takes a different approach (Kovarik et al., 2003) which at present is not as easily automated. As mentioned earlier, some product ion spectra will contain additional fragment ions not related to the analyte due to isobaric matrix peaks. However, MS/MS conditions previously obtained by using an ESI-MS/MS system can be directly ported over to the MALDI triple-quadrupole mass spectrometer. These conditions provide the advantage of product ion selection for SRM of the analyte. In the typical high-throughput environment, individual methods for each chemical entity are not normally utilized. Rather, the semioptimized template-style methods referred to above are often used wherein a few values of collision energy are combined with the appropriate SRM and polarity. These methods are ported to the MALDI triple quadmpole mass spectrometer, and no further... 

The reactor system of Zech et al. [35] is a good example of an integrated approach as it combines devices from different suppliers into a complex screening system. The reactor was manufactured at IMM (Fig. 4.4) and the sampling device delivered by AMTEC in Chemnitz. The catalyst preparation method was developed at the TU Chemnitz. The latter consists of an x/y-positioning robot supervised by a CCD camera. The sampling capillary was connected to a quadmpole mass spectrometer. This set-up has been used to screen up to 35 catalysts a day. 

In this method, chromium is extracted and preconcentrated from seawater with trifluoroacetylacetone (H(tfa) which complexes with trivalent but not hexavalent chromium. Chromium reacts with trifluoroacetylacetone in a 1 3 ratio to form an octahedral complex, Cr(tfa)3. The isotopic abundance of its most abundant mass fragment, Cr(tfa)2+was monitored by a quadmpole mass spectrometer. 

The hydrolytic displacement method was applied to four victims killed in the Tokyo subway attack (two died immediately and two later in hospital). Isopropyl methylphosphonic acid was identified at levels sufficient for full scan mass spectra to be obtained using a benchtop quadmpole mass spectrometer (46). Methylphosphonic acid was also identified. Some two years later, methylphosphonic acid... 

The experimental apparatus required to perform UK experiments is relatively simple (Figure 1). The two isotopic feeds are routed via a four-way valve to either a vent or the reactor. Their flow rates are set as closely as possible using standard mass flow controllers. The pressures of the two gas streams are then equalised using a differential pressure transducer and fine needle valve at the vent outlet. The reactor effluent is monitored continuously by a quadmpole mass spectrometer (Fisons Instruments GasLab 300) via a capillary sampling system. 

Figure 9.22 (a) Transmission quadmpole mass spectrometer. Rods A and B are tied together elec-... 

Magnetic sector or Quadmpole Mass Spectrometer, Electron Impact ionization 60,000-150,000 Fairly common... 

Tyler AN, Clayton E, Green BN. Exact mass measurement of polar organic molecules at low resolution using electrospray ionization and a quadmpole mass spectrometer. Anal Chem 1996 68(20) 3561-3569. 

Grimm-type glow discharge and quadmpole mass spectrometer [363]. 

In this section, the development of a LC lAMS is described. Section 5.2.2 summarizes the MS instrumentation for the alkali-metal ion/molecule association reaction a quadmpole mass spectrometer (QMS), combined with the Li+ ion attachment ionization source (model L-241G-I A, Canon Anelva Corp, Tokyo). The performance and response of this equipment and unique features are also presented (Sect. 5.2.3). Finally, the interesting applications are reviewed. There are some interesting and unusual applications of lAMS that broaden MS (i) intermediary free radical species detection, in the gas phase reactions, diagnosis of plasma and diamond film chemical vapor deposition (CVD), (ii) detection of atmospheric and interstellar species, (iii) detection of environmentally important species, and (iv) identification of unfamiliar or unstable species. Restriction of Hazardous Substances Detectives (RoHS) is also discussed. 

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