Applications of Isotope Dilution Mass Spectrometry

Samples Method Stable isotopes Precision References 

Human blood liver, muscle MC-ICP-MS (Neptune) separation by anion exchange chromatography 54 Fe, 56Fe, 57Fe 56Fe-0.0049% 57Fe-0.0071 % Walczyk et a/.45 

Aquatic systems (MeHg) (isotope dilution analysis) ICP-SFMS (Element) cold vapor technique 199 Fig, 200Hg, 201 Hg 202 Hg, Hg Hg, 20°Hg/2°2Hg 2° Hg/202Hg 0.6-1.4% LOD 0.2 ngH Sturup et al.ss 

Soils (depth profiling) ICP-SFMS (Element) separation by ion exchange 87Sr, 86Sr, 207 Pb, 206 Pb 87Sr/s6Sr-0.08 % 207pb/2°6pb o.07% Prohaska et a/.155 

The principle of the isotope dilution analysis (IDA) is described in Section 6.4. Due to its advantages as a definitive and accurate analytical method for the determination of element concentration via isotope ratio measurements, IDA is being increasingly applied in mass spectrometry, especially in ICP-MS and LA-ICP-MS as one of the most frequently used techniques. For example, the isotope dilution technique is employed in species analysis in biological systems, e.g., for the determination of mercury species in tuna material,or in aquatic systems. Further applications of the isotope dilution technique are the determination of selenomethionine in human blood serum by capillary HPLC-ICP (ORC) MS ° or sulfur speciation in gas oil, diesel or heating fuel by LA-ICP-MS. Evans and co-workers have reported on the high accuracy analysis of sulfur in diesel fuel by IDA. ICP-SFMS has been employed for Si species analysis in biological or clinical samples and 

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The fundamentals and several applications of isotope dilution mass spectrometry requiring accurate isotope ratio measurements are reviewed by Heumann.50,51 Today isotope dilution mass spectrometry (IDMS) is recognized as a primary measurement method, by means of which accurate results with sufficiently small uncertainties can be achieved and therefore it has been used in certifying the composition of reference materials. A requirement of isotope dilution analysis in mass spectrometry is to achieve equilibration of spike and sample so that very careful sample preparation steps, especially in solid mass spectrometry, are necessary when a homogeneous sample spike mixture is to be prepared. 

Webb, K.S., VAM report on calibration and traceability for primary chemical methods application of isotope dilution mass spectrometry (IDMS) to organic ultra-trace analysis (1994). 

De Leenheer, A.P. and Thienpont, L.M., Applications of isotope dilution-mass spectrometry in clinical chemistry, pharmacokinetics and toxicology, Mass Spectrom Rev., 11, 249-307 (1992). 

ICP-MS is used in practically every discipline where inorganic analytical support is required. This includes environmental, geological, biological, medical, nuclear, metallurgical (semiconductor industry) and nutritional studies. An important advantage of ICP-MS in quantitative analysis, required in many fields of application, is the substantial gain in precision and accuracy that can be achieved by the use of isotope-dilution mass spectrometry, where stable isotopes or... 

Yang, L., Mester, Z., and Sturgeon, R. E. (2002) Improvement in measurement precision with SPME by use of isotope dilution mass spectrometry and its application to the determination of tributyltin in sediment using SPME GC-ICP-MS. J. Aruil At. Spectrom., 17, 944-9. 

The bulk of modern analytical chemistry, perhaps 99% of it, and most of its tools he outside the limited scope and the simplified problems iterated in most recent papers on traceability. The application of the limited arsenal of primary methods in the remaining 1% often fails for other reasons because the method is often too complex or cumbersome to apply in any real practice (as in isotope dilution mass spectrometry) or... 

In the last decade or two, the advent of new instrumentation directed at elemental analysis has provided fertile new ground for expanded use of isotope dilution. Glow discharge mass spectrometry is in many ways the modem replacement for spark source and has similar impediments to ready application of isotope dilution. A recent report of Barshick et al. describes assaying lead in oil residues using the technique [21]. The obstacles spark source and glow discharge mass spectrometry both present to ready use of isotope dilution make it unlikely that widespread application of the technique will occur in conjunction with them. 

L. Yang, V. Colombini, P. Maxwell, Z. Mester, R. E. Sturgeon, Application of isotope dilution to the determination of methylmercury in fish tissue by solid-phase microextrac-tion gas chromatography-mass spectrometry, J. Chromatogr. A, 1011 (2003), 135-142. 

The application of speciated isotope dilution mass spectrometry (SIDMS) in speciation analysis was described and discussed by Huo et al. [236]. According to Encinar [237], isotopic analysis of a solution can be used to evaluate the application of various speciation forms of elements in food and in medications. 

Huo, D., Kingston, H.M., Larget, B. Application of isotope dilution in elemental speciation speciated isotope dilution mass spectrometry (SIDMS). In Caraso, J.A., Sutton, K.L., Ackley, K.L. (eds.) Elemental Speciation New Approaches for Trace Element Analysis, pp. 277-313. Elsevier Science B.V, Amsterdam (2000)... 

Murozumi et al. (9) determined the concentration of Pb in Greenland and Antarctic snow and ice by Isotope Dilution Mass Spectrometry (IDMS) (27). They added pure Pb tracer to their samples before chemically processing them. Both the mass of tracer and the water sample were measured. After thoroughly mixing the tracer with the sample Pb was isolated in a chemically pure form and the isotopic ratios were measured in a mass spectrometer. Simple comparison of the ° Pb abundance with the abundance of other isotopes in the mass spectrum allowed the amount of Pb in the sample to be determined. The technique is not limited to Pb, but is applicable to any element with two or more stable or... 

McLaren J. W., Beauchemin D. and Berman S. S. (1987) Application of isotope dilution ICP mass spectrometry to the analysis of marine sediments, Anal Chem 59 610-613. 

Longerich, H.P. (1989) The application of isotope dilution to inductively coupled plasma-mass spectrometry. Atom. Spectrosc., 10, 112-115. 

Isotope dilution mass spectrometry (ID-MS) is widely accepted as a quantification procedure of proven accuracy in elemental analysis and isotope ratio measurements [4]. Several areas of research in nuclear science, geochronology, medicinal chemistry, environmental science, and agricultural science have benefited from this technique. ID-MS is applicable to all elements that have at least two stable isotopes. Monoisotopic elements can be analyzed only if they have a long-lived natural or artificial radioisotope. For example, iodine and thorium have been determined with spikes of the long-lived isotopes 29i and 25 Th, respectively [44]. TI-MS and ICP-MS are the methods of choice for accurate ID-MS analysis. ICP-MS has the advantage that several elements can be analyzed simnltaneously under the same experimental conditions. Other ionization techniqnes discussed in this chapter have also been coupled with ID-MS. 

Methods also employed for determination of inorganic lead include isotope dilution mass spectrometry, flame atomic fluorescence spectrometry, and molecular absorption spectrometry, but these methods are not used for routine applications. Methods for the determination of organolead speciation are high-performance liquid chromatography with a separation of the species and flame AAS or UV detection. 

Yip Y-C, Sham W-C. Applications of collision/reaction cell technology in isotope dilution mass spectrometry. Trends Anal Chem. 2007 26 727-43. 

Other methodologies fall into the category of definitive or alternative reference methodologies. The definitive method for lead, against which other methods are qualified for reference use, and the one employed for standard sample lead certification by the National Institute of Science and Technology (NIST), is isotope-dilution mass spectrometry (IDMS). Among its cardinal virtues, in addition to accuracy and precision, are sensitivity and applicability to many lead-containing environmental matrices. 

Calibration using the double-spike method is an ingenious application of isotope dilution in mass spectrometry. Admixing the measurand and the spike (calibrant) results in a mixture, the isotopic composition of which is governed by the conservation of matter. Two sets of equations can be established one that describes the conservation of matter during the mixing, and the other that expresses the relationship between the measured and true isotope amount ratios, that is, the discrimination law ... 

The application of isotope dilution analysis to ICP-MS-based hyphenated techniques, for example HPLC-ICP-MS, can be divided into two diflerent modes the spedes-unspecific mode and species-specific mode. The two modes are illustrated in Figure 4.6. Because IDA-ICP-MS relies on the measurement of isotope ratios by mass spectrometry, the traditional interference to the accuracy and precision of IDA should all be considered and some biases need further correction in this case, such as spectral interferences, dead time of detector, mass discrimination, and statistic and stability of ion counting. 

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