Comparison of powdered enamel sample pretreatment methods for strontium isotope analysis
Most researchers assume minimal impact of pretreatment on strontium isotope ratios (87Sr/86Sr) for bones and teeth, and methods vary tremendously. We compared 14 pretreatment methods, including no prep other than powdering enamel, ashing, soaking in water, an oxidizing agent (bleach or hydrogen pero...
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Frontiers Media S.A.
2023-03-01
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| Series: | Frontiers in Environmental Chemistry |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fenvc.2023.1114807/full |
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| author | Brooke Erin Crowley Brooke Erin Crowley Emily Michelle Bruff Simpson Sarah Jayne Hammer Joshua Michael Smith Thomas Martin Johnson |
| author_facet | Brooke Erin Crowley Brooke Erin Crowley Emily Michelle Bruff Simpson Sarah Jayne Hammer Joshua Michael Smith Thomas Martin Johnson |
| author_sort | Brooke Erin Crowley |
| collection | DOAJ |
| description | Most researchers assume minimal impact of pretreatment on strontium isotope ratios (87Sr/86Sr) for bones and teeth, and methods vary tremendously. We compared 14 pretreatment methods, including no prep other than powdering enamel, ashing, soaking in water, an oxidizing agent (bleach or hydrogen peroxide) or acetic acid (0.1 M, 1.0 M, and 1.0 M buffered with calcium acetate), and a combination of these steps. We prepared and analyzed aliquots of powdered molar enamel from three proboscideans (one modern captive Indian elephant, Elephas maximus indicus; one Pleistocene mastodon, Mammut americanum; and one Miocene gomphothere, Afrochoerodon kisumuensis). Each pretreatment was performed in triplicate and we measured 87Sr/86Sr, Sr concentration, and uranium (U) concentration, using the same lab space and instrumentation for all samples. Variability in 87Sr/86Sr and Sr and U concentrations was considerable across pretreatments. Mean 87Sr/86Sr across methods ranged from 0.70999 to 0.71029 for the modern tooth, 0.71458 to 0.71502 for the Pleistocene tooth, and 0.70804 to 0.70817 for the Miocene tooth. The modern tooth contained the least Sr and negligible U. The Pleistocene tooth contained slightly more Sr and measurable amounts of U, and the Miocene tooth had approximately 5x more Sr and U than the Pleistocene tooth. For all three teeth, variance in 87Sr/86Sr, Sr concentrations, and U concentrations among replicates was statistically indistinguishable across pretreatments, but there were apparent differences among pretreatments for the modern and Pleistocene teeth. Both contained relatively little Sr, and it is possible that small amounts of exogenous Sr from reagents, building materials or dust affected some replicates for some pretreatments. For the modern tooth, median 87Sr/86Sr varied considerably (but statistically insignificantly) across pretreatments. For the Pleistocene tooth, variability in median 87Sr/86Sr was also considerable; some pretreatments were statistically distinct but there were no obvious patterns among methods. For the Miocene tooth, variability in median 87Sr/86Sr was much smaller, but there were significant differences among pretreatments. Most pretreatments yielded 87Sr/86Sr and Sr concentrations comparable to, or lower than, untreated powder, suggesting selective removal of exogenous material with high 87Sr/86Sr. Further evaluation of the mechanisms driving isotopic variability both within and among pretreatment methods is warranted. Researchers should clearly report their methods and avoid combining data obtained using different methods. Small differences in 87Sr/86Sr could impact data interpretations, especially in areas where isotopic variability is low. |
| first_indexed | 2024-04-10T06:17:30Z |
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| institution | Directory Open Access Journal |
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| language | English |
| last_indexed | 2024-04-10T06:17:30Z |
| publishDate | 2023-03-01 |
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| spelling | doaj.art-8fa2e7b71e73404ebb6bd91cf34bd7ed2023-03-02T06:18:38ZengFrontiers Media S.A.Frontiers in Environmental Chemistry2673-44862023-03-01410.3389/fenvc.2023.11148071114807Comparison of powdered enamel sample pretreatment methods for strontium isotope analysisBrooke Erin Crowley0Brooke Erin Crowley1Emily Michelle Bruff Simpson2Sarah Jayne Hammer3Joshua Michael Smith4Thomas Martin Johnson5Department of Geosciences, University of Cincinnati, Cincinnati, OH, United StatesDepartment of Anthropology, University of Cincinnati, Cincinnati, OH, United StatesDepartment of Geosciences, University of Cincinnati, Cincinnati, OH, United StatesDepartment of Geosciences, University of Cincinnati, Cincinnati, OH, United StatesDepartment of Geology, University of Illinois Urbana-Champaign, Urbana, IL, United StatesDepartment of Geology, University of Illinois Urbana-Champaign, Urbana, IL, United StatesMost researchers assume minimal impact of pretreatment on strontium isotope ratios (87Sr/86Sr) for bones and teeth, and methods vary tremendously. We compared 14 pretreatment methods, including no prep other than powdering enamel, ashing, soaking in water, an oxidizing agent (bleach or hydrogen peroxide) or acetic acid (0.1 M, 1.0 M, and 1.0 M buffered with calcium acetate), and a combination of these steps. We prepared and analyzed aliquots of powdered molar enamel from three proboscideans (one modern captive Indian elephant, Elephas maximus indicus; one Pleistocene mastodon, Mammut americanum; and one Miocene gomphothere, Afrochoerodon kisumuensis). Each pretreatment was performed in triplicate and we measured 87Sr/86Sr, Sr concentration, and uranium (U) concentration, using the same lab space and instrumentation for all samples. Variability in 87Sr/86Sr and Sr and U concentrations was considerable across pretreatments. Mean 87Sr/86Sr across methods ranged from 0.70999 to 0.71029 for the modern tooth, 0.71458 to 0.71502 for the Pleistocene tooth, and 0.70804 to 0.70817 for the Miocene tooth. The modern tooth contained the least Sr and negligible U. The Pleistocene tooth contained slightly more Sr and measurable amounts of U, and the Miocene tooth had approximately 5x more Sr and U than the Pleistocene tooth. For all three teeth, variance in 87Sr/86Sr, Sr concentrations, and U concentrations among replicates was statistically indistinguishable across pretreatments, but there were apparent differences among pretreatments for the modern and Pleistocene teeth. Both contained relatively little Sr, and it is possible that small amounts of exogenous Sr from reagents, building materials or dust affected some replicates for some pretreatments. For the modern tooth, median 87Sr/86Sr varied considerably (but statistically insignificantly) across pretreatments. For the Pleistocene tooth, variability in median 87Sr/86Sr was also considerable; some pretreatments were statistically distinct but there were no obvious patterns among methods. For the Miocene tooth, variability in median 87Sr/86Sr was much smaller, but there were significant differences among pretreatments. Most pretreatments yielded 87Sr/86Sr and Sr concentrations comparable to, or lower than, untreated powder, suggesting selective removal of exogenous material with high 87Sr/86Sr. Further evaluation of the mechanisms driving isotopic variability both within and among pretreatment methods is warranted. Researchers should clearly report their methods and avoid combining data obtained using different methods. Small differences in 87Sr/86Sr could impact data interpretations, especially in areas where isotopic variability is low.https://www.frontiersin.org/articles/10.3389/fenvc.2023.1114807/fulldiagenenesisacetic acidhydroxyapatitesodium hyplochloritehydrogen peroxideMC-ICPMS |
| spellingShingle | Brooke Erin Crowley Brooke Erin Crowley Emily Michelle Bruff Simpson Sarah Jayne Hammer Joshua Michael Smith Thomas Martin Johnson Comparison of powdered enamel sample pretreatment methods for strontium isotope analysis Frontiers in Environmental Chemistry diagenenesis acetic acid hydroxyapatite sodium hyplochlorite hydrogen peroxide MC-ICPMS |
| title | Comparison of powdered enamel sample pretreatment methods for strontium isotope analysis |
| title_full | Comparison of powdered enamel sample pretreatment methods for strontium isotope analysis |
| title_fullStr | Comparison of powdered enamel sample pretreatment methods for strontium isotope analysis |
| title_full_unstemmed | Comparison of powdered enamel sample pretreatment methods for strontium isotope analysis |
| title_short | Comparison of powdered enamel sample pretreatment methods for strontium isotope analysis |
| title_sort | comparison of powdered enamel sample pretreatment methods for strontium isotope analysis |
| topic | diagenenesis acetic acid hydroxyapatite sodium hyplochlorite hydrogen peroxide MC-ICPMS |
| url | https://www.frontiersin.org/articles/10.3389/fenvc.2023.1114807/full |
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