Thermal ionization mass analysis

Bourdon B, Joron J-L, Allegre CJ (1999) A method for Pa analysis by thermal ionization mass spectrometry in silicate rocks. Chem Geol 157 147-151... 

A. Deyhle. Improvements of Boron Isotope Analysis by Positive Thermal Ionization Mass Spectrometry Using Static Multicollection of CS2BO2 Ions. Int. J. Mass Spectrom., 206(2001) 79-89. 

The relatively small mass differences for most of the elements discussed in this volume requires very high-precision analytical methods, and these are reviewed in Chapter 4 by Albarede and Beard (2004), where it is shown that precisions of 0.05 to 0.2 per mil (%o) are attainable for many isotopic systems. Isotopic analysis may be done using a variety of mass spectrometers, including so-called gas source and solid source mass spectrometers (also referred to as isotope ratio and thermal ionization mass spectrometers, respectively), and, importantly, MC-ICP-MS. Future advancements in instrumentation will include improvement in in situ isotopic analyses using ion microprobes (secondary ion mass spectrometry). Even a small increase in precision is likely to be critical for isotopic analysis of the intermediate- to high-mass elements where, for example, an increase in precision from 0.2 to 0.05%o could result in an increase in signal to noise ratio from 10 to 40. 

Traditionally thermal ionization mass spectrometry was the instrument of choice for the isotopic analysis of metals because thermal ionization produced an ion beam with a very small kinetic energy spread ( 0.5 eV). Therefore only a magnetic mass analyzer is needed to resolve one isotope from another. Moreover, ionization of unwanted material, such as atmospheric contaminates, hydrocarbons from pump oil, or production of doubly ionized particles is almost non existent, thus background counts are minimized and signal-to-noise ratio is maximized. 

Moriguti T, Nakamura E (1993) Precise lithium isotope analysis by thermal ionization mass spectrometry using lithium phosphate as an ion source. Proc Japan Acad Sci 69B 123-128 Moriguti T, Nakamura E (1998a) High-yield lithium separation and precise isotopic analysis for natural rock and aqueous samples. Chem Geol 145 91-104... 

Ireland TR, Fahey AJ, Zinner EK (1991) Hibonite-bearing microspherules a new type of refractory inclusions with large isotopic anomalies. Geochim Cosmochim Acta 55 367-379 Johnson CM, Beard BL (1999) Correction of instrumentally produced mass fractionation during isotopic analysis of Fe by thermal ionization mass spectrometry. Int J Mass Spect 193 87-99 Jungck MHA, Shimamura T, Lugmair GW (1984) Calcium isotope variations in Allende. Geochim Cosmochim Acta 48 2651-2658... 

Efforts to measure Mo isotope variations, using thermal ionization mass spectrometry (TIMS), can be traced back to the early 1960s. Early studies were provocative Murthy (1962 1963) reported that the Mo isotope composition in some iron meteorites deviated from that of others, and from terrestrial Mo, by 10 %o/amu, while Crouch and Tuplin (1964) reported mass dependent variations and mass independent isotopic anomalies among terrestrial molybdenites. As discussed below, Wetherill (1964) subsequently demonstrated isotopic uniformity among iron meteorites to better than 1 %o/amu. It is likely that earlier reports were affected by analytical artifacts due to inadequate correction of Mo isotope fractionation during analysis. 

Johnson, C.M. and Beard, B.L., 1999. Correction of instrumentally produced mass fractionation during isotopic analysis of Fe by thermal ionization mass spectrometry. International J. Mass Spectrometry, 193 87-99. 

A main characteristic of TIMS is that positively or negatively charged ions of the analyte are also formed and used for mass spectrometric analysis. In negative thermal ionization mass spectrometry (NTIMS) elements or molecules with a relatively high electron affinity (/iea > 2eV) can be... 

S. Ahmed, N. Jabeen, and E. ur Rehman, Determination of Lithium Isotopic Composition by Thermal Ionization Mass Spectrometry, Anal. Chem. 2002, 74, 4133 L. W. Green, J. J. Leppinen, and N. L. Elliot, Isotopic Analysis of Lithium as Thermal Dilithium Fluoride Ions, Anal. Chem. 1988,60, 34. 

Lead curse tablets from Roman Carthage contain variable amounts of very small metallic inclusions. Electron microprobe analysis confirmed these metallic inclusions were bronze, brass, and a Sn-Sb alloy. This was interpreted as possible evidence of lead metal recycling. Six samples were chosen to represent a range of tablets containing the minimum to the maximum number of inclusions. Thermal ionization mass spectrometry of the Pb isotopes in the curse tablets appear to define a mixing line, with the tablets containing the least number of inclusions plotting closest to the Tunisian lead ore isotope ratios. 

A.D. were found in old mines, and sizable slag deposits suggest at least some level of lead exploitation during Roman times (2). By the careful selection of Roman lead artifacts likely to have been manufactured in Carthage, and the use of lead isotope analysis, it may be possible to confirm the use of Tunisian lead ores during the Roman period. In this preliminary study, analysis of 22 curse tablets by electron microprobe analysis (EMPA) and six tablets by thermal ionization mass spectrometry (TIMS) suggest that these artifacts might be used to better understand Roman lead use and trade. 

The isotope 40K can be analyzed in natural water samples with the Cherenkov counting technique.2 3 Because of the lack of a suitable radiotracer for K and the similarity between the chemistries of rubidium and potassium, 86Rb can be used as a tracer for K.4 Also, thermal ionization mass spectrometry (TIMS) has been used to determine 40K in environmental samples. The interference of mass 40 can be solved by double spiking with 43Ca/48Ca the procedure for the routine high-precision isotope analysis of the K-Ca system will then be free of Ca fractionations.5... 

As mentioned, thermal ionization mass spectrometry is the area in which isotope dilution developed and in which it has received the widest range of applications. One of thermal ionization s major limitations is that it is essentially a single-element technique in no way can it be considered multielement in the sense that numerous elements can be assayed in a single analysis. It is thus highly desirable to mate isotope dilution with multielement analysis capability. Spark source mass spectrometry for years dominated elemental analysis, but the nature of the samples (solids) made use of isotope dilution difficult. Use of a multielement spike was reported as long ago as 1970 by Paulsen et al. [17], however, and more recently by Carter et al. [18] and by Jochum et al. [19,20]. 

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