Trace isotope dilution mass spectrometry

Isotope dilution mass spectrometry has been used to determine traces of copper in seawater [298,299]. 

In the analysis of seawater, isotope dilution mass spectrometry offers a more accurate and precise determination than is potentially available with other conventional techniques such as flameless AAS or ASV. Instead of using external standards measured in separate experiments, an internal standard, which is an isotopically enriched form of the same element, is added to the sample. Hence, only a ratio of the spike to the common element need be measured. The quantitative recovery necessary for the flameless atomic absorption and ASV techniques is not critical to the isotope dilution approach. This factor can become quite variable in the extraction of trace metals from the salt-laden matrix of seawater. Yield may be isotopically determined by the same experiment or by the addition of a second isotopic spike after the extraction has been completed. 

Trace Impurities in Fuels by Isotope Dilution Mass Spectrometry... 

In view of these issues, we have over several years undertaken a substantial research programme to develop definitive methods appropriate for in-house certification of matrix RMs, particularly for analytes at trace levels. These definitive measurement methods, most of which use isotope dilution mass spectrometry (IDMS), been the subject of extensive validation, including CCQM key comparisons and pilot studies involving other national measurement institutes. Hence, we are now able to augment interlaboratory data with data obtained at LGC using these very accurate measurements. We have also... 

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)... 

Isotope dilution mass spectrometry can be used to determine element concentrations at trace and macro levels with high sensitivity and high accuracy Several examples of sensitive and accurate measurements with IDMS are Illustrated in Table I for foodstuffs and biological matrices ( 2 4 >35 >62 >68) The accuracy of IDMS has been used to certify elemental concentrations in a wide variety of matrices with concentrations ranging over eight orders of magnitude ... 

Examples of primary methods used in determining multi-isotope trace elements are isotope dilution-based techniques (e.g. isotope dilution mass spectrometry), enabling traceability of the results to SI units. For organometallic compounds, the use of these techniques will hence guarantee traceability to SI units for the compounds in the extracts. 

Heumann K. G. (1982) Isotope dilution mass spectrometry for micro-and trace element determination, Trends Anal Chem 1 357-361. 

US EPA (Environmental Protection Agency) (2002) Current drinking water standards. Washington. Waidmann E, Hilpert Kand Stoeppler M (1990) Ti trace determination in human specimens by isotope dilution mass spectrometry (IDMS) using thermal ionisation. Fresenius J Anal Chem 337 134-135. 

The book offers the reader in its first part a general and as detailed as necessary introduction into the basic principles and methods, starting with sampling, sample storage and sample treatment. These steps are of utmost importance for each analytical procedure. This is followed by the description of the potential of a number of modern trace analytical methods, i.e. atomic absorption and emission spectrometry, voltammetry, neutron activation and isotope dilution mass spectrometry. The latter method is an important reference method within a general concept for quality control and the generation of reference materials which are an absolute must in this context. 

De Bievre, P. (1990). Isotope Dilution Mass Spectrometry what can it do for accuracy in Trace Analysis Fres. Z. Anal. Chem. 337, 766-771. 

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). 

For some radionuclides, only the direct measurement is needed, based on calibration with a radionuclide standard and reference to the measured sample mass. For other radionuclides, the isotope ratio to its stable element is needed. An example of a more complex situation is measurement of the 14C/12C isotope ratio of an environmental or archeological sample in comparison to the modern atmospheric CO2 value. This value must be adjusted for anthropogenic 14C produced by atmospheric testing of nuclear weapons and by other nuclear operations, and also for changes in atmospheric CO2 with cosmic-ray flux fluctuations over time. For an element such as Pu, which has no stable isotope, the total quantity is measured by isotope dilution mass spectrometry in which the sample is traced (or spiked) with 242Pu or 244Pu (see Section 17.3.3). 

Isotope dilution mass spectrometry is the most accurate and most sensitive of all trace element analytical techniques and is particularly suited to measuring very low concentrations. The method is described in some detail by Henderson and Pankhurst (1984) and depends upon the addition of an isotopic tracer or spike to the sample. The spike contains a known concentration of a particular element whose isotopic composition is also known. If a known amount of spike and a known amount of sample are mixed, and the isotope ratio of the mixture determined, the concentration of the element in the sample can be calculated. 

Isotope dilution mass spectrometry is an accurate and sensitive technique for determining toxic trace elements in food matrices. Lead, cadmium, and thallium have been analyzed rapidly down to very low levels by ICP-MS. The latter technique is particularly useful for simultaneous measurement of a wide range of elements. Because the toxicity of an element can be highly dependent on its chemical form, ICP-MS is also useful in the speciation of toxic minerals in foodstuffs by combination with HPLC or SEC. 

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