Isotope dilution analysis biology

Accurate determination of the biological important element, selenium, in blood serum by isotope dilution analysis using ICP-QMS with octopole collision cell (Agilent 7500ce, Tokio, Japan) is described by Schaumloffel and coworkers.55 A recovery of selenium from human serum reference material was only 78 % when hydrogen was applied as collision gas but 96.7 % using xenon as a non-reactive collision gas to eliminate isobaric interferences. A detection limit of 3.3p,gl-1 was achieved.55... 

Certain techniques such as neutron activation analysis and stable isotope dilution analysis offer very powerful and sensitive methods for the determination of trace metals, but involve considerable effort and access to extensive facilities and so are not suited for routine laboratory determinations. However, they have been used to determine trace metal levels accurately in homogeneous biological materials, which are now used as reference materials for other techniques. 

Yoshinaga and Morita used isotope dilution in conjunction with ICP-MS to measure mercury in biological and environmental samples [45]. The same group used microwave-induced plasma mass spectrometry for the isotope dilution analysis of selenium in biological materials [46]. Analysis of nickel via isotope dilution and ICP-MS has been reported by Patriarca et al [47]. 

L. H. Reyes, J. M. M. Gayon, J. I. G. Alonso, A. Sanz-Medel, Determination of selenium in biological materials by isotope dilution analysis with an octapole reaction system ICP-MS, J. Anal. Atom. Spectrom., 18 (2003), 1210-1216. 

The principle of the isotope dilution analysis (IDA) is described in Section 6.4. Due to its advantages as a definitive and accurate analytical method for the determination of element concentration via isotope ratio measurements, IDA is being increasingly applied in mass spectrometry, especially in ICP-MS and LA-ICP-MS as one of the most frequently used techniques. For example, the isotope dilution technique is employed in species analysis in biological systems, " e.g., for the determination of mercury species in tuna material,or in aquatic systems. Further applications of the isotope dilution technique are the determination of selenomethionine in human blood serum by capillary HPLC-ICP (ORC) MS ° or sulfur speciation in gas oil, diesel or heating fuel by LA-ICP-MS. Evans and co-workers have reported on the high accuracy analysis of sulfur in diesel fuel by IDA. ICP-SFMS has been employed for Si species analysis in biological or clinical samples and... 

Sanz-Medel and co-workers reported on selenium determination in biological samples by isotope dilution analysis in ICP-QMS with an octopole collision cell." The argon based isobaric interference arising during measurements of °Se was eliminated by using a hydrogen flow of 4 ml min in the octopole cell, so that it is possible to determine Se with a detection limit of 14pgg. ... 

The main and unique advantage of this method is the fact that quantitative separation of the element or compound to be determined is not necessary. It is substituted by measuring any fraction. This advantage is most clearly illustrated by an example from biology if the blood volume of an animal is to be determined, it is obvious that the animal will not survive the extraction of the whole amount of blood to be measured. By application of isotope dilution analysis, a small measmed volume V of a solution is injected that contains a measured activity of a radionuclide of low radiotoxicity. Mixing is effected by blood circulation. After some minutes, a small volume of blood is taken and the activity is measured. In analogy to eq. (17.15), the unknown volume is... 

In complex mixtures of compounds (for exanq>le, in organic synthesis or biochemical systems) it may be quite difficult to ascertain the exact amount of a specific component. A widely used technique of considerable value is isotope dilution analysis. This can be iq)plied either with stable isotopes, in which case the detector is a mass spectrometer, or with radioactive isotopes, using measuring techniques presented in Chapter 8. The use of stable isotopes is usually limited to geologic samples, as described in 2.3, but may be applied to biological samples using highly enriched or However, the technique with... 

When George Karl von Hevesy developed the technique of isotope dilution analysis (chapter 3), his source of lead isotopes was the natural decay of radioactive substances. In his 1944 Nobel lecture, Hevesy related his utopian wish from that period, some two decades earlier [Imagine] the great progress which might be expected if radioactive indicators of the common elements were made available to chemical and biological research. This was the discovery of the Joliot-Curies made in 1934, a... 

A major attraction is the ability to perform isotope ratio measurements, e.g., in many geological applications to determine the age of rocks, biological and geological fractionation of elements, anthropogenic origin, stable isotope tracer studies, and isotope dilution analysis. In this respect, magnetic sector... 

Microdetermination of DNA in Biological Materials by Gas Chromatographic and Isotope Dilution Analysis of Thymine Content... 

Heumann, K.G. Kastenmayer, P. Zeininger, H. Lead and Thallium Trace Determination in the Ppm and Ppb Range in Biological Material by Mass Spectro-metric Isotope Dilution Analysis. Fre-... 

Isotope dilution analysis for protein quantification with ICP-MS is usually performed by linked techniques based on the coupling to an effective separation method, such as HPLC or CE. Generally, proteins to be analyzed should contain ICP-MS-detectable elements, including both naturally occurring and artificially labeled. After introduction of the spike that has different isotopic composition from the analyte, the elemental isotope ratio can be measured in ICP-MS and thus the detectable elements can be absolutely quantified by use of the isotope dilution equation. If proteins have been identified with biological mass spectrometry, or the elemental stoichiometric ratios of proteins have been known, the amount of proteins can be deduced from the elemental concentration of the proteins. 

Valles Mota, J. R, Ruiz Encinar, J., Fernandez de la Campa, M. R., and Garcia Alonso, J. I. (1999). Determination of cadmium in environmental and biological reference materials using isotope dilution analysis with a double focusing ICP-MS A comparison with quadrupole ICP-MS./. Anal. At. Spectrom. 14(9), 1467. 

Rodriguez Martln-Doimeadios, R. C., Krupp, E., Amouroux, D., and Donard, O. F. X. (2002) Application of isotopically labeled methyhnercury for isotope dilution analysis of biological samples using gas chromatography/ICPMS. A/iaZ. Chern., 74,2505-12. 

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