Inductively coupled plasma isotope applications

Accurate, precise isotope ratio measurements are important in a wide variety of applications, including dating, examination of environmental samples, and studies on drug metabolism. The degree of accuracy and precision required necessitates the use of special isotope mass spectrometers, which mostly use thermal ionization or inductively coupled plasma ionization, often together with multiple ion collectors. 

Since about 1990, however, inductively coupled plasma (ICP, see Section 2.1.5) has become increasingly popular at the expense of TI in this area of application [9]. Although TI can provide better results for some analyses, ICP is more versatile and requires less sample preparation effort. Moreover, the advantage of better precision for TI is often compromised by the sample, for example, sample inhomogeneity. Nevertheless, there are still many examples where TI is used, such as for isotope analysis [10-13] and geochronology [14]. 

The observed range of natural variations of 5 Ca is about 4 to 5%o in terrestrial materials and up to 50%o in high temperature condensate minerals in carbonaceous chondrites. The typical reproducibility of measurements is about +0.15%o. Broader application of Ca isotope measurements in geochemistry may be possible, particularly if the reproducibility can be improved to 0.05%o to 0.03%o. There is hope that this can be achieved either with inductively coupled plasma source mass spectrometry (Halicz et al. 1999) or with a new generation of multi-collector thermal ionization mass spectrometers (Heuser et al. 2002). 

In the environment, Mo isotope research began in earnest with the application of multiple-collector inductively coupled plasma mass spectrometry. While much work remains to be done, this early research points to promising applications in paleoceanography, and beyond. 

The Nickel Producers Environmental Research Association (NiPERA) is sponsoring research on the application of inductively coupled plasma-mass spectroscopy (ICP-MS) to isotopic analysis of nickel in biological samples, on the development of sampling instrumentation for assessing workers exposure to nickel in the nickel industry, and on methods for utilizing newly developed analytical methods, such as laser beam ionization mass spectrometry, for the identification and speciation of nickel compounds in powders and dusts with particular reference to nickel refining. 

The quasi-simultaneous separation and determination of lanthanides and actinides by ion chromatography inductively coupled plasma mass spectrometry combined with the isotope dilution technique and the further use of ion chromatography for the determination of fission products and actinides in nuclear applications are described by Betti et ul.10 48 68... 

Further applications of laser ablation inductively coupled plasma mass spectrometry for the trace and ultratrace and isotope analysis of long-hved radionuclides are discussed in references1 3,9actinide elements is presented by Geipel.91... 

Isotope ratios provide insight into the physical and chemical processes that cause alteration of their values. Their application is expanding as analytical procedures become more sophisticated and sensitive, and as the extent of scientific knowledge increases. As in many fields, much work done today would have been impossible a few years ago. With the advent of multicollector inductively coupled plasma (ICP) mass spectrometers, it is probable that routine use of thermal ionization will diminish, but it seems that it will always play a role in applications in which utmost sensitivity is required. 

J. R. Dean, L. Ebdon, R. Massey, Selection of mode for the measurement of lead isotope ratios by inductively coupled plasma mass spectrometry and its application to milk powder analysis, J. Anal. Atom. Spectrom., 2 (1987), 369-374. 

J. J. Sloth, E. H. Larsen, The application of inductively coupled plasma dynamic reaction cell mass spectrometry for measurement of selenium isotopes, isotope ratios and chromatographic detection of selenoamino acids, J. Anal. Atom. Spectrom., 15 (2000), 669-672. 

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