ICP-SFMS

The very low Hg concentration levels in ice core of remote glaciers require an ultra-sensitive analytical technique as well as a contamination-free sample preparation methodology. The potential of two analytical techniques for Hg determination - cold vapour inductively coupled plasma mass spectrometry (CV ICP-SFMS) and atomic fluorescence spectrometry (AFS) with gold amalgamation was studied. 

ICP-SFMS (Thermo Finnigan, Flement) with cold vapour generation was developed with a guard electrode and a gold amalgamation device using an Au-sorbent for sample pre-concentration to improve the sensitivity. Instrumental parameters of ICP-SFMS such as take-up time, heating temperature of Au-sorbent, additional gas flow, and sample gas flow were optimized. Detection limit calculated as 3 times the standard deviation of 10 blanks was 0,05 ng/1, RSD = 7-9 %. 

Figure 2.11 Sensitivity for selected long-lived radionuclides measured by ICP-SFMS (Element, Thermo Fisher Scientific) with (yellow) and without (green) shielded torch (CE - guard electrode). (]. S. Becker and H. ). Dietze. Int. ). Mass Spectrom. Ion Proc. 197, 1-35 (2000). Reproduced by permission of Elsevier.)...

Due to the non-linear geometry of all sector field instruments (ICP-SFMS see Figure 5.1, right column, at the bottom) the instrumental background is about one order of magnitude better (0.1-0.5 cps) than in quadrupole ICP-MS. 

Figure 5.2 Overview of ICP-MS instrumentation quadrupole-based ICP-MS with and without colli-sion/reaction cell, sector field ICP-MS with single ion collector (ICP-SFMS) and multiple ion collector ICP-MS (MC-ICP-MS) and time-of-flight ICP-MS.

Double-focusing Sector Field ICP Mass Spectrometers with Single Ion Collector (ICP-SFMS)... 

Figure 5.9 Double-focusing sector field ICP-MS (ICP-SFMS, Element XR, Thermo Fisher Scientific, Bremen) with extended dynamic range up to 1 013 (a), arrangement of ion detector systems is shown at top right, (b). (Reproduced by permission of Thermo Fisher Scientific, Bremen.)22...

Table 5.3 Characteristics of ICP-SFMS (Element, Thermo Fisher Scientific,...

As a calibration procedure in ICP-MS via calibration curves, external calibration is usually applied whereby the blank solution is measured followed by a set of standard solutions with different analyte concentrations (at least three, and it is better to analyze more standard solutions in the same concentration range compared to the sample). After the mass spectrometric measurements of standard solutions, the calibration curve is created as a plot of ion intensities of analyte measured as a function of its concentration, and the linear regression line and the regression coefficient are calculated. As an example of an external calibration, the calibration curve of 239 Pu+ measured by ICP-SFMS with a shielded torch in the pgC1 range is illustrated in Figure 6.15. A regression... 

Figure 6.15 Calibration curve of239 Pu+ at ultratrace concentration level measured by ICP-SFMS.

For some applications, precipitation and co-precipitation, which is often incomplete, is utilized. As an example, for trace matrix separation the procedure for plutonium determination by ICP-SFMS in urine after trace matrix separation is summarized in Figure 6.29.86 87 The limit of detection for 239 Pu ultratrace determination in one litre of urine based on enrichment factor of 100 using the DIHEN in ICP-SFMS was 1.02- 10 18g mF1.86... 

For many decades, TIMS was the isotope analytical technique of choice, but due to instrumental developments in ICP-MS, especially with multiple ion collectors (MC-ICP-SFMS), and the advantages of ICP-MS in comparison to TIMS (e.g., higher element sensitivities, faster isotope ratio measurements, comparable precision and accuracy, practically no restriction on the ionization potential of chemical elements, time independent mass fractionation and the possibility of additional multi-element analysis at trace and ultratrace level and fewer, less time-consuming sample preparation steps75), TIMS will be replaced in future by powerful ICP-MS to an ever greater extent. 

Zircon, opal ICP-SFMS (Element) Brilliant Quantel/266 and 206pb/238u 0.099-0.021 geochronology Tieplo134... 

Human bones ICP-SFMS (Element) Ablascope/ 213 nm 87Sr/86Sr 0.1 -0.2 biology and life science Prohaska et al.IJJ... 

Ceological glasses ICP-SFMS (Element) New Wave UP/213nm earth science, Jochum et al.128... 

Selected applications of isotope analysis on stable isotopes by MC-ICP-MS compared to ICP-SFMS are summarized in Table 8.5.29,45,55 109,152-158... 

Soils (depth profiling) ICP-SFMS (Element) separation by ion exchange 87Sr, 86Sr, 207 Pb, 206 Pb 87Sr/s6Sr-0.08 % 207pb/2°6pb o.07% Prohaska et a/.155... 

Figure 8.6 ICP-SFMS spectrum of 238 UH+ measured at mass resolution of 4450 on natural uranium diluted with D20. (M. Zoriy, L. Halicz, M. Ketterer, P. Ostapczuk, R. Hille, and j. S. Becker, /. Anal. At. Spectrom., 19, 675 (2004). Reproduced by permission of the Royal Society of Chemistry.)...

Soils ICP-SFMS (VG Axiom) after separation 239Pu, 240Pu, 241 Pu 240Pu/239Pu 0.18-0.35 241Pu/239Pu 0.003-0.004 Ketterer et al.97... 

Soils and sediments ICP-SFMS (Element) 239Pu, 240Pu 240Pu/239Pu 0.18-0.2 Nygren et al. 55... 

Soils (Chernobyl) LA-ICP-SFMS (Element) (LINA-Spark) 239 Pu, 240 Pu °-25Pgg 240Pu/239Pu = 0.4 Boulyga et al. 82... 

Moss, plant, soil, sediment ICP-SFMS (VG Axiom) after separation 239 Pu, 240 Pu, 240Pu/239Pu 0.19-0.26 Agarande et al. 79... 

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