Determination of 236U/238U isotope ratio in contaminated environmental samples using different ICP-MS instruments

Self Cite

High isotopic abundance sensitivity is desirable for the measurement of low-abundance isotopes in the presence of neighboring high-abundance isotopes. This is of interest when analyzing ultra low concentrations of trace elements or isotopes in the presence of elements or isotopes with much higher concentrations (e.g., radionuclides included in a matrix of stable isotopes). In this study, a quadrupole-based inductively coupled plasma mass spectrometer with a hexapole collision cell (ICP-CC-QMS), Platform ICP (Micromass UK), was used to study the improvement of abundance sensitivity using uranium and lutetium as examples. The median kinetic energy of 238 U 1 ions was about 1.2 eV and 0.9 eV when helium was introduced as a collision gas at flow rates of 5 ml min 21 and 10 ml min 21 , respectively. In the latter case, the proportion of ions with relatively high energy decreased significantly, which improved both the transmission of ions through the hexapole collision cell and mass selection by the quadrupole mass spectrometer. When introducing helium into the collision cell a reduction in peak tail of high-abundance isotopes by up to three orders of magnitude, depending on the mass analyzed, was observed. The abundance sensitivity for 236 U/ 238 U isotope ratio was improved from 2.3 6 10 25 to 6.3 6 10 28 . Abundance sensitivities as low as 3.5 6 10 28 , 6.6 6 10 28 and 2.0 6 10 28 were achieved at masses m 2 2.5 u, m 2 1.5 u and m 1 2.5 u (m~174.94 u for 175 Lu), respectively. Reducing the kinetic energy also improved the mass resolution by about 10%. However, increasing the mass resolution of the quadrupole instrument had a significantly lower influence on abundance sensitivity than reducing the ion energy by collision with helium atoms. The present study of the effect of the pressurized ion guide on abundance sensitivity was limited to some extent because of the relatively high background count rate of the Daly-type ion detector in the ICP-CC-QMS system. An ion detector possessing a low background would be desirable for further studies. Improved abundance sensitivity can be useful in analyzing long-lived radionuclides like 236 U and 129 I in the presence of high-abundance stable isotopes like 238 U and 127 I.

Section: Abundance Sensitivity In Icp-cc-qmsmentioning

confidence: 99%

Improvement of abundance sensitivity in a quadrupole-based ICP-MS instrument with a hexapole collision cell

Boulyga¹,

Becker²

2002

Self Cite

“…35 This abundance sensitivity of sector field instruments is less than that of quadrupole instruments. 36 The average concentration of stable strontium in urine was experimentally determined to be approximately 5 mg L 21 ; abundance sensitivity was studied at medium mass resolution (m/Dm~4450) using a standard solution with concentration of 1 mg mL 21 of strontium. In order to correct for possible interferences, intensity was measured at the masses m ¡ 0.5 u, m ¡ 1.5 u, m ¡ 2.5 u, etc.…”

Section: Abundance Sensitivitymentioning

confidence: 99%

Determination of 90Sr at ultratrace levels in urine by ICP-MS

Vonderheide

Zoriy²,

Izmer³

et al. 2004

Sr appears as a radionuclide in the decay series of nuclear fission and can therefore be found in nuclear waste or released by nuclear accidents. Current methods for the detection of this radionuclide are time consuming and may be prone to a large variety of interferents. In this work, inductively coupled plasma mass spectrometry is explored for the determination of 90 Sr in the presence of stable zirconium in urine. Specific techniques are investigated to remove this as well as other contributions to the background at m/z~90. A quadrupole ICP-MS equipped with a hexapole collision cell is first explored (final LOD~2 ng L 21 for water samples), however, the desired limit of detection for 90 Sr in urine is quite low (0.02 pg L 21). The performance of a double-focusing sector field ICP mass spectrometer (ICP-SFMS) is further investigated, which allows measurement of 90 Sr at the ultratrace level. Other potential interferences were investigated and instrumental detection limits are calculated as 3 pg L 21 for water samples. Final parameters include the use of a cool plasma and medium mass resolution in ICP-SFMS. The method is applied to the analysis of 90 Sr extracted from urine using a crown ether extraction resin and concentrated (enrichment factor: 200); high levels of natural strontium in the separated fraction (of about 1 mg mL 21 ) equate to higher detection limits (80 pg L 21) due to 88 Sr 1 at m/z~90 and the relatively low abundance sensitivity of ICP-SFMS at medium mass resolution of 6 6 10 27 . This detection limit in the separated fraction corresponds to the detection limit of 0.4 pg L 21 in the original urine sample. The recovery of 90 Sr, determined with the developed analytical method in spiked urine samples, was in the range of 82-86%.

“…182 Further on, a large number of publications covers the field of radionuclide determination applying sector field devices, making use of the high sensitivity, the isotope ratio capabilities (even at large ratios) and the application of high mass resolution. [194][195][196][197][198] A review of Ketterer and Szechenyi shows how ICP-SFMS has become one of the most popular methods for the routine and high-throughput determination of plutonium and other transuranic elements because of its speed of analysis, simplicity of sample preparation, straightforward operation, sensitivity, low background and ability to resolve interfering polyatomic ions. 199 Lariviere et al 200 used the high sensitivity of ICP-SFMS for the rapid and automated sequential determination of ultra-trace long-lived actinides in air filters.…”

Section: Geological and Radionuclide Applicationsmentioning

confidence: 99%

Inductively coupled plasma- and glow discharge plasma-sector field mass spectrometry : Part II. Applications

Jakubowski

Prohaska

Vanhaecke

et al. 2011