Specificity analysis high-resolution mass spectrometry

As with the bulk POM and DOM, the operationally defined fractions of UDOM and humic substances are quantified by elemental analysis and via broad molecular-class detection. Other strategies involve measurement of the natural isotopic composition, both stable and radioactive, of the various fractions. Efforts are underway to develop more sophisticated techniques, such as solid-state NMR and high-resolution mass spectrometry, far identification of specific bonds and functional groups. 

In comparison with NMR, mass spectrometry is more sensitive and, thus, can be used for compounds of lower concentration. While it is easily possible to measure picomoles of compounds, detection limits at the attomole levels can be reached. Mass spectrometry also has the ability to identify compounds through elucidation of their chemical structure by MS/MS and determination of their exact masses. This is true at least for compounds below 500 Da, the limit at which very high-resolution mass spectrometry can unambiguously determine the elemental composition. In 2005, this could only be done by FTICR. Orbitrap appears to be a good alternative, with a more limited mass range but a better signal-to-noise ratio. Furthermore, mass spectrometry allows relative concentration determinations to be made between samples with a dynamic range of about 10000. Absolute quantification is also possible but needs reference compounds to be used. It should be mentioned that if mass spectrometry is an important technique for metabolome analysis, another key tool is specific software to manipulate, summarize and analyse the complex multivariant data obtained. 

Patterson DG Jr., Isaacs SG, Alexander LR, Turner WE, Hampton L, Bernert JT, Needham LL (1991), in IARC Scientific Publication No. 108.,Environmental Carcinogens Methods of Analysis and Exposure Measurement, Vol. 11 Polychlorinated Dioxins and Dibenzofurans . determination of specific polychlorinated dibenzo-p-dioxins and dibenzofurans in blood and adipose tissue by isotope-dilution high-resolution mass spectrometry", p. 299-342, Eds. Rappe C, Buser HR, Dodet B, O Neill IK, International Agency for Research on Cancer, Lyon... 

This chapter provides an overview of mass spectrometer function and operation. It describes specific instrument types with demonstrated or potential application for measuring radionuclides and surveys the application of these instruments to radionuclide detection. Finally, it discusses the circumstances under which use of mass spectrometers is advantageous, the type of mass spectrometer used for each purpose, and the conditions of sample preparation, introduction and analysis. Its perspective is from a national laboratory active in environmental and non-proliferation monitoring. It emphasizes isotope ratio measurements, but mass spectrometric measurements also provide isotope mass information. Several recent books describe elemental and isotope ratio mass spectrometry in far greater detail than is presented here (Barshick et al., 2000 De Laeter, 2001 Montaser, 1998 Nelms, 2005 Platzner, 1997 Tuniz et al., 1998). High-resolution mass spectrometry forms the basis of the mass scale used for elemental and isotopic masses (Coplen, 2001), but this application of MS falls outside the scope of this chapter. 

Endogenous interferences and MALDI matrix cluster can complicate the analysis of xenobiotic drug compounds and their metabolites in MSI. The use of hyphenated techniques (either MS" or IMS) or high-resolution mass spectrometry can serve to increase analyte specificity. Although instrument... 

High resolution mass spectrometry offers high selectivity for the analysis of PCTs and toxaphene congeners in environmental and biological samples and avoids the specific internal interferences and the effect of environmental matrices. Both HRGC El MS and HRGC-ECNTMS in the SIM mode can be used as... 

This procedure ( ) has been used since 1982 by EPA for routine investigations. The analytical protocol requires complete extraction of the sample followed by liquid chromatographic cleanup and isomer-specific 2,3,7,8-TCDD analysis by high resolution gas chromatography/low resolution mass spectrometry. The extraction begins with ten grams of soil which is spiked with internal surrogate CI4-2378-... 

Confirmation of the identities of nitrosamines generally is accompHshed by gas chromatography—mass spectrometry (gc/ms) (46,87). High resolution gc/ms, as well as gc/ms in various single-ion modes, can be used as specific detectors, especially when screening for particular nitrosamines (87) (see Analytical LffiTHODS Trace and residue analysis). 

---