Applications of Atomic MS

The high-temperature plasma decomposes the sample into its elements. A high percentage of these elements are ionized in the plasma and therefore do not need to pass through an additional ionization source. ICP-MS is particularly useful for rapid multielement analysis of metals and nonmetals at concentrations of ppb and ppt. 

Only unit mass (low) resolution is required to discriminate between different elements, because isotopes of different elements differ by 1 u as can be seen in Appendix 

There are only a few isotopic overlaps between elements, so one can usually find an isotope to measure for any given element. In fact, there is only one element that cannot be definitely identified by ICP-MS, the element indium. (One of the problems at the end of the chapter asks you to explain why.) The abundance of each isotope is a quantitative measure of that element s concentration in the original sample. The isotope patterns for the elements are shown in Fig. 10.36. 

The applications discussed are from many forms of atomic MS, including ICP-MS, glow discharge MS (GDMS), and coupled chromatography-lCP-MS. The websites of the major instmment manufacturers (Agilent, LECO, PerkinElmer, Thermo Electron, and Varian, to name a few for ICP-MS) are an excellent source for applications of the techniques. 

Some of the many uses for ICP-MS include analysis of environmental samples for ppb levels of trace metals and nonmetals, the analysis of body fluids for elemental toxins such as lead and arsenic, determination of trace elements in geological samples, metals and alloys, 

The most common samples analyzed by ICP-MS are aqueous solutions. The sample is dissolved in acid, digested or fused in molten salt (all described in Chapter 1), and then diluted to volume with water. All acids, bases, reagents, and water must be of extremely high purity, given the sensitivity of the ICP-MS technique. Ultratrace metal grade acids, solvents, and deionized water systems are all commercially available. The aqueous solution is introduced into the plasma using a peristaltic pump, nebulizer, and spray chamber system identical to those used for ICP-OES (Chapter 7). 

Quantitative analysis by ICP-MS is usually done with external calibration standards and the addition of internal standards to all standards and samples. When a large number of elements across the periodic table are to be determined, it is usual to add Li, Y, In, Tb, and Bi and measure the ions Li, In, Tb, and ° Bi as internal standards (unless you need to measure one of these elements as an analyte). Not all of the internal standard elements are used to quantitate every analyte. The internal standard that is most closely matched in first ionization potential to the analyte is generally used, since this will compensate for ionization interferences in matrices containing easily ionized elements such as Na. Results obtained using this approach are generally very accurate and precise. Table 10.23 presents typical spike recovery and precision data for ICP-MS determination of 25 elements in a certified reference material (CRM) Trace Elements In Drinking Water from High-Purity Standards, Charleston, SC. 

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Gas and liquid chromatography directly coupled with atomic spectrometry have been reviewed [178,179], as well as the determination of trace elements by chromatographic methods employing atomic plasma emission spectrometric detection [180]. Sutton et al. [181] have reviewed the use and applications of ICP-MS as a chromatographic and capillary electrophoretic detector, whereas Niessen [182] has briefly reviewed the applications of mass spectrometry to hyphenated techniques. 

During the last decade, research efforts in the field of LC-MS have changed considerably. Technological problems in interfacing appear to be solved, and a number of interfaces have been found suitable for the analysis of flavonoids. These include TSP, continuous-flow fast-atom bombardment (CF-FAB), ESI, and APCI. LC-MS is frequently used to determine the occurrence of previously identified compounds or to target the isolation of new compounds (Table 2.11). LC MS is rarely used for complete structural characterization, but it provides the molecular mass of the different constituents in a sample. Then, further structural characterization can be performed by LC-MS-MS and MS-MS analysis. In recent years, the combination of HPLC coupled simultaneously to a diode-array (UV-Vis) detector and to a mass spectrometer equipped with an ESI or APCI source has been the method of choice for the determination of flavonoid masses. Applications of LC-MS (and LC-MS-MS) in flavonoid... 

Rains TC, Watters RL Jr, Epstein MS. 1984. Application of atomic absorption and plasma emission spectrometry for environmental analysis. Environment International 10 163-168. 

The instrumentation and interfaces that had been used up to 1998 in CWC-related LC/MS analysis were summarized previously (4). At that time, sources that operate at atmospheric pressure, using electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI), were displacing their predecessors that used thermospray ionization or continuous flow fast atom bombardment. Atmospheric pressure ionization (API), either ESI or APCI, is now the method of choice in CWC-related analysis and will be the focus of this current review. A small number of recent applications involving alternative types of ionization are also included. For earlier applications of LC/MS to chemical weapons (CW) analysis, using thermospray and other ionization methods, the reader is referred to our previous review (4). The other major trend has been the increasing availability and ease of use of less-expensive bench-top quadrupole and... 

Miscellaneous. Trace analyses have been performed for a variety of other materials. Table 9 lists some uses of electrothermal atomic absorption spectrometry (etaas) for determination of trace amounts of elements in a variety of matrices. The applications of icp/ms to geological and biological materials include the following (165) ... 

An overview of the application of atomic spectrometric techniques to the elemental analysis of milk samples has been given. Elemental composition of milk, its nutritional role, sample preparation methods for analysis and measurement techniques have been described in detail. It appears that ICP-MS and ICP-AES are the most reliable techniques for the multielemental analysis of major, minor, and trace elements in milk samples. 

In principle, the applications of ICP-MS resemble those listed for OES. This technique however is required for samples containing sub-part per billion concentrations of elements. Quantitative information of nonmetals such as P, S, I, B, Br can be obtained. Since atomic mass spectra are much simpler and easier to interpret compared to optical emission spectra, ICP-MS affords superior resolution in the determination of rare earth elements. It is widely used for the control of high-purity materials in semiconductor and electronics industries. The applications also cover the analysis of clinical samples, the use of stable isotopes for metabolic studies, and the determination of radioactive and transuranic elements. In addition to outstanding analytical features for one or a few elements, this technique provides quantitative information on more than 70 elements present from low part-per-trillion to part-per-million concentration range in a single run and within less than 3 min (after sample preparation and calibration). Comprehensive reviews on ICP-MS applications in total element determinations are available. " ... 

Other Techniques. A growing technique related to lc/ms and regarded as complementary to it is that of capillary zone electrophoresis/mass spectrometry (cze/ms) (22). Using cze/ms, high resolution separation of water-soluble compounds is accompHshed by the principles of electrophoresis (qv). The sample is then coupled to the mass spectrometer by electrospray ionization (23) or a fast atom bombardment interface (fab) to produce molecular ions (24). Biotechnology applications of cze/ms have great potential (25). 

Early reports revealed the electrochemical formation of Li-Sn intermetallics, which could provide theoretical capacities close to 1000 mAh g in lithium cells [27]. A second impulse was received by a material patented by Fuji tin composite oxides in which tin oxides were the starting material [28]. More recently, the commercialization of the Nexelion battery by SONY gave new attraction to tin-based electrodes, with the special feature of being noncrystalline, which adds new value to the use of spectroscopic techniques. Since the late 1990s, a large number of papers have been published on the application of " Sn MS in the study of tin-based electrode materials. MS was found to be extremely useful in the analysis of the different steps commonly found during the electrochemical reaction of tin compounds with lithium (i) reduction of tetra- or divalent tin atoms to the metallic state, followed by the most important step, (ii) a reversible formation of Li-Sn intermetallics. 

The application of AFM and other techniques has been discussed in general terms by several workers [350-353]. Other complementary techniques covered in these papers include FT-IR spectroscopy, Raman spectroscopy, NMR spectroscopy, surface analysis by spectroscopy, GC-MS, scanning tunnelling microscopy, electron crystallography, X-ray studies using synchrotron radiation, neutron scattering techniques, mixed crystal infrared spectroscopy, SIMS, and XPS. Applications of atomic force spectroscopy to the characterisation of the following polymers have been reported polythiophene [354], nitrile rubbers [355], perfluoro copolymers of cyclic polyisocyanurates of hexamethylene diisocyanate and isophorone diisocyanate [356], perfluorosulfonate [357], vinyl polymers... 

See also Biochemical Applications of Mass Spectrometry Biomedical Applications of Atomic Spectroscopy Chromatography-MS, Methods Fast Atom Bombardment Ionization in Mass Spectrometry Isotopic Labelling in Mass Spectrometry. 

See also Chromatography-NMR, Applications Chromatography-MS, Methods Environmental and Agricultural Applications of Atomic Spectroscopy Luminescence, Theory. 

See also Biochemical Applications of Mass Spectrometry Chemical Structure Information from Mass Spectrometry Chemical Ionization in Mass Spectrometry Chromatography-MS, Methods Forensic Science, Applications of Atomic Spectroscopy Forensic Science, Applications of IR Spectroscopy Hyphenated Techniques, Applications of in Mass Spectrometry Ion Trap Mass Spectrometers Isotopic Labelling Mass Spectrometry Medical Applications of Mass Spectrometry MS-MS and MS Negative Ion Mass Spectrometry, Methods Quadrupoles, Use of in Mass Spectrometry. 

This chapter describes the instrumentation and basic analytical capabilities of ICP-AES and ICP-MS. Some illustrative examples of analyses involving rare earths as either analyte or matrix are also described. The chosen cases reflect some of the major areas of interest but are not meant to represent all the work in the literature. Complete reviews of publications in ICP-AES are provided, in even years, in the Emission Spectrometry section of the review issue of Analytical Chemistry (Keliher et al. 1986). Applications for analysis of specific sample types, e.g., waters, metals, etc., are also reviewed therein in odd years. Analytical uses of ICPs are surveyed regularly in the ICP Information Newsletter, the Journal of Analytical Atomic Spectrometry, and the Journal of Analytical Spectroscopy. ICP-AES is also described in detail in three recent books (Boumans 1987, Montaser and Golightly 1987, Thompson and Walsh 1983), and a fourth monograph deals with applications of ICP-MS (Date and Gray 1989). Numerous reviews on ICPs (Fassel 1978), ICP-AES (Barnes 1978), and ICP-MS (Douglas and Houk 1985, Houk 1986, Gray 1985, Houk and TTiompson 1988) are also available. 

Applications On-line SPE-GC and SPE-GC-MS couplings find wide application for sample cleanup of biological, environmental and industrial analysis of aqueous samples [67]. SPE-GC-AED/MS is ideally suited for the (nontarget) screening of hetero-atom-containing compounds in aqueous samples, and allows confirmation plus identification in one run [68]. Specific applications of hyphenated SPE-GC systems for polymer/additive analysis were not identified. 

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