Thermal ionization mass spectrometry table analysis

Methods of stable Isotope analysis. Three methods of a-nalysls have been used for analysis of stable Isotopes of minerals neutron activation analysis (NAA) (10), gas-chromato-graph-mass spectrometry (GC/MS) (11), and thermal Ionization mass spectrometry (TI/MS) ( 6). The maximum attainable precision of each of these analytical methods Is compared In Table III (2). 

Magnetic sector thermal Ionization mass spectrometry Is capable of far better precision and accuracy than the other two methods of analysis. A recent comparative study of NAA and Tl/MS zinc analysis In human blood samples demonstrated the marked difference In precision between the two methods (12). The standard deviation of zinc ratio determinations was 0.13% for TI/MS and 8.3% for NAA. It Is likely that, while maximum attainable precision for both methods Is better than this (see Table III), these levels of precision are the best which can be achieved In biological samples. The excellent precision of TI/MS Is offset by several disadvantages. Analysis Is slow, requires considerable skill and experience, and Is expensive. Extensive sample preparation Is required to obtain pure samples pure enough for accurate analysis. However, the high degree of precision attainable by this method make It the only choice when excellent precision and accuracy (e.g. within 1%) are required. 

A number of analytical techniques have been used to determine ppm to ppt levels of vanadium in biological materials. These include neutron activation analysis (NAA), graphite furnace atomic absorption spectrometry (GFAAS), spectrophotometry, isotope dilution thermal ionization-mass spectrometry (IDMS), and inductively coupled plasma atomic emission spectrometry (ICP-AES). Table 6-1 summarizes the analytical methods for determining vanadium in biological materials. 

Table 11 -1 lists the most important typos of atomic mass spectromelry. Hislorically, thermal ionization mass spectrometry and spark. source mass spectrometry were the lirsl mass spectromdric methods developed for qualiialive and quantitative elemenlul analysis, and these types of procedures still Had applications, although they are now overshadowed by some of (he other methods listed in Table 11-1, particularly indue lively coupled plasma mass spectrometry (1((PMS),... 

Most elements of the periodic table have been investigated for the presence of isotopic anomalies as part of various cosmochemical studies (Figure 10.3) and many have even been studied at great detail. For light elements that are either present as gases in samples or which are readily volatilized, such analyses are typically conducted by gas source mass spectrometry. In the past, isotopic analysis of metallic and metalloid elements were primarily carried out using either thermal ionization mass spectrometry (TIMS) or, for in situ measurements, secondary... 

Table 1. Lead contamination blanks for serum collection, processing, and analysis by isotope dilution thermal ionization mass spectrometry in the WIGS Trace Metal/Mass Spectrometry facihty. University of California, Santa Cruz. Lead values are based upon repeated measurements.

---