Calcium isotope analysis by mass spectrometry

Abstract

The variations in the isotopic composition of calcium caused by fractionation in heterogeneous systems and by nuclear reactions can provide insight into numerous biological, geological, and cosmic processes, and therefore isotopic analysis finds a wide spectrum of applications in cosmo‐ and geochemistry, paleoclimatic, nutritional, and biomedical studies. The measurement of calcium isotopic abundances in natural samples has challenged the analysts for more than three decades. Practically all Ca isotopes suffer from significant isobaric interferences, whereas low‐abundant isotopes can be particularly affected by neighboring major isotopes. The extent of natural variations of stable isotopes appears to be relatively limited, and highly precise techniques are required to resolve isotopic effects. Isotope fractionation during sample preparation and measurements and instrumental mass bias can significantly exceed small isotope abundance variations in samples, which have to be investigated. Not surprisingly, a TIMS procedure developed by Russell et al. (Russell et al., 1978. Geochim Cosmochim Acta 42: 1075–1090) for Ca isotope measurements was considered as revolutionary for isotopic measurements in general, and that approach is used nowadays (with small modifications) for practically all isotopic systems and with different mass spectrometric techniques. Nevertheless, despite several decades of calcium research and corresponding development of mass spectrometers, the available precision and accuracy is still not always sufficient to achieve the challenging goals. The present article discusses figures of merits of presently used analytical methods and instrumentation, and attempts to critically assess their limitations. In Sections 2 and 3, mass spectrometric methods applied to precise stable isotope analysis and to the determination of 41Ca are described. Section 4 contains a short summary of selected applications, and includes tracer experiments and the potential use of biological isotope fractionation in medical studies, paleoclimatic and paleoceanographic, and other terrestrial as well as extraterrestrial investigations. © 2009 Wiley Periodicals, Inc., Mass Spec Rev 29:685–716, 2010

Studies on Isotope Ratio Measurement of Cl by Inductively Coupled Plasma Triple-quad Mass Spectrometry

“…Isotope ratio measurement of elements is well recognized to be increasingly widespread use in disciplines such as bioavailability studies using stable isotope tracers, [1][2][3][4][5][6] isotope abundance measurements in nuclear chemistry, 6-10 the determination of isotope variations in geological, environmental and cosmic samples including age determinations, 3,4,[11][12][13][14][15][16][17][18][19] food authenticity, 3,4,20 or forensic science. 3,4,21,22 Isotope ratio measurement is also important for the production of accurate analytical results in trace element determinations by isotope dilution mass spectrometry (IDMS).…”

“…3,4,21,22 Isotope ratio measurement is also important for the production of accurate analytical results in trace element determinations by isotope dilution mass spectrometry (IDMS). [23][24][25][26][27][28][29] Isotope ratio measurements have traditionally been carried out by isotope ratio mass spectrometry (IRMS) 3,12,13,20,22 and by thermal ionization mass spectrometry (TIMS).…”

“…[23][24][25][26][27][28][29] Isotope ratio measurements have traditionally been carried out by isotope ratio mass spectrometry (IRMS) 3,12,13,20,22 and by thermal ionization mass spectrometry (TIMS). 4,8,14,20 Disciplines of IRMS are the ability to accurately and precisely measure variations in the abundance of isotope ratios of light elements such as H, C, N, O and S. On the other hand, TIMS can cover the whole range of elements from Li to U except for the gaseous elements measured by IRMS. An inductively coupled plasma mass spectrometry (ICPMS) has also been more and more involved in isotope ratio measurements, especially for heavy elements such as Fe, Cu, Mo, Cd, Cs, Nd, Hf, W, Tl, Pb, U, and so on.…”

Assessment of international reference materials for isotope-ratio analysis (IUPAC Technical Report)

“…The δ 44/42 Ca values can be measured in this manner with an uncertainty below 0.2 ‰ [169]. For comprehensive reviews, see DePaolo [170] and Boulyga (2010) [173]. Isotope-amount ratio determined using synthetic isotope mixtures.…”

Advances in Isotope Ratio Mass Spectrometry and Required Isotope Reference Materials

“…Mg, Ca or Fe, are used as so-called tracer in nutrition physiology to unravel metabolism and pathways of these particular elements. [12][13][14] In isotope dilution mass spectrometry the enriched isotope is used as so-called spike for the quantification of element or species concentrations. 15,16) All isotope research, whether investigation of natural isotopic variations or investigation of man-made isotope shifts, requires the determination of one or more isotope ratio typically carried out by mass spectrometric techniques.…”