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Procedures for precise measurements of 135Cs/137Cs atom ratios in environmental samples at extreme dynamic ranges and ultra-trace levels by thermal ionization mass spectrometry

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@article{c7cdca6203d742aaa4cd604fbc1816e8,
title = "Procedures for precise measurements of 135Cs/137Cs atom ratios in environmental samples at extreme dynamic ranges and ultra-trace levels by thermal ionization mass spectrometry",
abstract = "Determination of 135Cs/137Cs atom ratios has the potential to be a powerful tool for nuclear forensics and monitoring environmental processes. We present optimized chemical separation techniques and thermal ionization mass spectrometry (TIMS) protocols to obtain precise 135Cs/137Cs atom ratios for a range of environmental sample types. We use a combination of double AMP-PAN separation and Sr-spec resin column purification to yield excellent separation from the alkali metals (Rb separation factor > 600), which normally suppress ionization of Cs. A range of emission activators for the ionization of Cs were evaluated and glucose solution yielded the optimal combination of a stable Cs+ beam, minimal low-temperature polyatomic interferences and improved ionization efficiency. Mass-spectrometric determination of low abundance 135Cs and 137Cs is compromised by the presence of a very large 133Cs+ beam, which may be scattered and cause significant spectral interferences. These are explored using multi-static Faraday cup – ion counter methods and a range of energy filter settings. The method is evaluated using environmental samples and standards from regions affected by fallout from Chernobyl (IAEA-330) and Fukushima nuclear disasters. Where the intensity of 133Cs+ is large relative to 135Cs+ and 137Cs+ (< 30 cps), minor polyatomic interferences need to be considered. In the absence of a standard with 135, 137Cs/133Cs < 1 × 10−8, we explored the reproducibility of 135Cs/137Cs atom ratios at these high dynamic ranges and extremely low abundance (137Cs ≈ 12 fg g−1) for sediments from an estuarine setting in SW England, UK.",
keywords = "Radiocaesium, TIMS, Interferences, Scattered 133Cs+",
author = "James Dunne and David Richards and Hart Chen",
year = "2017",
month = "11",
day = "1",
doi = "10.1016/j.talanta.2017.06.033",
language = "English",
volume = "174",
pages = "347--356",
journal = "Talanta",
issn = "0039-9140",
publisher = "Amsterdam:Elsevier",

}

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TY - JOUR

T1 - Procedures for precise measurements of 135Cs/137Cs atom ratios in environmental samples at extreme dynamic ranges and ultra-trace levels by thermal ionization mass spectrometry

AU - Dunne, James

AU - Richards, David

AU - Chen, Hart

PY - 2017/11/1

Y1 - 2017/11/1

N2 - Determination of 135Cs/137Cs atom ratios has the potential to be a powerful tool for nuclear forensics and monitoring environmental processes. We present optimized chemical separation techniques and thermal ionization mass spectrometry (TIMS) protocols to obtain precise 135Cs/137Cs atom ratios for a range of environmental sample types. We use a combination of double AMP-PAN separation and Sr-spec resin column purification to yield excellent separation from the alkali metals (Rb separation factor > 600), which normally suppress ionization of Cs. A range of emission activators for the ionization of Cs were evaluated and glucose solution yielded the optimal combination of a stable Cs+ beam, minimal low-temperature polyatomic interferences and improved ionization efficiency. Mass-spectrometric determination of low abundance 135Cs and 137Cs is compromised by the presence of a very large 133Cs+ beam, which may be scattered and cause significant spectral interferences. These are explored using multi-static Faraday cup – ion counter methods and a range of energy filter settings. The method is evaluated using environmental samples and standards from regions affected by fallout from Chernobyl (IAEA-330) and Fukushima nuclear disasters. Where the intensity of 133Cs+ is large relative to 135Cs+ and 137Cs+ (< 30 cps), minor polyatomic interferences need to be considered. In the absence of a standard with 135, 137Cs/133Cs < 1 × 10−8, we explored the reproducibility of 135Cs/137Cs atom ratios at these high dynamic ranges and extremely low abundance (137Cs ≈ 12 fg g−1) for sediments from an estuarine setting in SW England, UK.

AB - Determination of 135Cs/137Cs atom ratios has the potential to be a powerful tool for nuclear forensics and monitoring environmental processes. We present optimized chemical separation techniques and thermal ionization mass spectrometry (TIMS) protocols to obtain precise 135Cs/137Cs atom ratios for a range of environmental sample types. We use a combination of double AMP-PAN separation and Sr-spec resin column purification to yield excellent separation from the alkali metals (Rb separation factor > 600), which normally suppress ionization of Cs. A range of emission activators for the ionization of Cs were evaluated and glucose solution yielded the optimal combination of a stable Cs+ beam, minimal low-temperature polyatomic interferences and improved ionization efficiency. Mass-spectrometric determination of low abundance 135Cs and 137Cs is compromised by the presence of a very large 133Cs+ beam, which may be scattered and cause significant spectral interferences. These are explored using multi-static Faraday cup – ion counter methods and a range of energy filter settings. The method is evaluated using environmental samples and standards from regions affected by fallout from Chernobyl (IAEA-330) and Fukushima nuclear disasters. Where the intensity of 133Cs+ is large relative to 135Cs+ and 137Cs+ (< 30 cps), minor polyatomic interferences need to be considered. In the absence of a standard with 135, 137Cs/133Cs < 1 × 10−8, we explored the reproducibility of 135Cs/137Cs atom ratios at these high dynamic ranges and extremely low abundance (137Cs ≈ 12 fg g−1) for sediments from an estuarine setting in SW England, UK.

KW - Radiocaesium

KW - TIMS

KW - Interferences

KW - Scattered 133Cs+

U2 - 10.1016/j.talanta.2017.06.033

DO - 10.1016/j.talanta.2017.06.033

M3 - Article

VL - 174

SP - 347

EP - 356

JO - Talanta

JF - Talanta

SN - 0039-9140

ER -