|
|
| |
Applications
|
|
|
|
| |
|
|
|
|
| |
|
|
| |
Boron isotopes |
|
|
|
| |
Boron consists of two naturally-occurring isotopes, B-10 and B-11, with abundances of approximately 19.9% and 80.1%, respectively. The lighter isotope is used in the nuclear power industry, since B-10 is an efficient neutron absorber and can therefore be used to control the neutron flux in pressurized water reactors. In practice, boric acid is added to the reactor cooling water, neutron absorption converting B-10 to tritium (H-3) and alfa-particles via the B-10(n, 2 alpha)H-3 reaction [1]. During reactor operation, the concentration of B-10 in the cooling water changes, a process that can be monitored by measurements of boron isotope ratios.
Clinical trials are currently underway in several countries using boron neutron capture therapy (BNCT) for cancer treatment [2]. Boron-containing compounds, designed for efficient uptake by cancer cells, are administered. When tumors are then irradiated by low energy neutrons, B-10 present in the cells is converted to a lithium isotope in the reaction B-10(n,alfa)Li-7. The ionizing radiation released in the form of alfa-particles then kills the cancer cell. For BNCT studies, there is an evident need for measurements of boron isotopes.
|
|
ALS Scandinavia AB can provide measurements of boron isotope ratios in water samples as well as solid materials using ICP-MS with a precision better than 2% relative standard deviation. The accuracy of boron isotope measurements was recently established when results of an inter-comparison of boron isotope and concentration measurements were published [3]. Data from this laboratory were found to be in agreement with the international consensus values for water (blue triangles in diagram) and rock (red squares) samples.
|
|
| |
[1] Choppin, G.; Liljenzin, J.-O.; Rydberg, J.: Radiochemistry and Nuclear Chemistry, 3rd Ed., Butterworth-Heinemann, Woburn (2002) Chapters 19 and 20.
[2] Sauerwein, W.; Zurlo, A.: The EORTC Boron Neutron Capture Therapy (BNCT) Group: achievements and future projects. Eur. J. Cancer 38 (2002) S31.
[3] Gonfianti, R.; Tonarini, S.; Gröning, M.; Adorni-Braccessi, A.; Al-Ammar, A. S.; Astner, M.; Bächler, S.; Barnes, R. M.; Bassett, R. L.; Cocherie, A.; Deyhle, A.; Dini, A.; Ferrara, G.; Gaillardet, J.; Grimm, J.; Guerrot, C.; Krähenbühl, U.; Layne, G.; Lemarchand, D.; Meixner, A.; Northington, D. J.; Pennisi, M.; Reitzerová, E.; Rodushkin, I.; Sugiura, N.; Surberg, R.; Tonn, S.; Wiedenbeck, M.; Wunderli, S.; Xiao, Y.; Zack, T.: Intercomparison of boron isotope and concentration measurements. Part II. Evaluation of results. Geostand. Newslett. 27 (2003) 41.
|
|
| |
|
|
| |
Iron isotopes in whole blood
|
|
|
|
| |
As shown by recent research [4], the iron present in human whole blood has an isotopic composition that differs significantly from that found in typical rocks and steel. There are also clear indications that the distribution of iron isotopes present in the blood of women and men differs. This is illustrated in the figure to the right, where changes in isotope ratios are expressed as delta-values, defined as per mil (‰) deviations from a standard of known isotopic composition:
d56 = [(Fe-56/Fe-54)blood/(Fe-56/Fe-54)standard - 1]·1000 ‰
d57 = [(Fe-57/Fe-54)blood/(Fe-57/Fe-54)standard - 1]·1000 ‰
The standard used is the iron isotopic reference material IRMM-014 supplied by the Institute for Reference Materials and Measurements, Geel, Belgium [5].
|
|
ALS Scandinavia AB can now offer measurements of iron isotopes in whole blood samples using a method developed in co-operation with research scientists from Luleå University of Technology [6]. Using state of the art MC-ICP-MS instrumentation, d56- and d57-values with precision levels better than 0.1 ‰ are provided.
|
|
| |
[4] Walczyk, T.; von Blanckenburg, F.: Natural iron isotope variations in human blood. Science 295 (2002) 2065.
[5] Taylor, P. D. P.; Maeck, R.; De Bièvre, P.: Determination of the absolute isotopic composition and atomic weight of a reference sample of natural iron. Int. J. Mass Spectrom. Ion Process. 121 (1992) 111.
[6] Stenberg, A.; Malinovsky, D.; Rodushkin, I.; Andrén, H.; Pontér, C.; Öhlander, B.; Baxter, D. C.: Separation of Fe from whole blood matrix for precise isotopic ratio measurements by MC-ICP-MS: a comparison of different approaches. J. Anal. At. Spectrom. 18 (2003) 23. |
|
|
