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Stable isotope amount ratio analysis by using high-resolution continuum source graphite furnace molecular absorption spectrometry

  • Analysis of stable isotopes has been used as proof of provenance of mineral and biological samples, to estimate a contamination source and to determine geological processes. This kind of analysis needs high accuracy and precision for reliable conclusions. Currently, stable isotope analysis is dominated by mass spectrometric techniques that are time consuming and expensive. Here we present a fast and low cost alternative for isotope analysis of boron and magnesium: high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS-GFMAS). Two stable isotope systems were evaluated separately: boron (10B:11B) and magnesium (24Mg:25Mg:26Mg). Their isotope amount ratios were estimated by monitoring their absorption spectra in-situ generated monohydrides. The molecular absorption spectrum of a XH molecule (X= B or Mg) with n isotopes would be a linear combination of n isotopologue spectra and the amount of each component (isotope) could be calculated by a multivariateAnalysis of stable isotopes has been used as proof of provenance of mineral and biological samples, to estimate a contamination source and to determine geological processes. This kind of analysis needs high accuracy and precision for reliable conclusions. Currently, stable isotope analysis is dominated by mass spectrometric techniques that are time consuming and expensive. Here we present a fast and low cost alternative for isotope analysis of boron and magnesium: high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS-GFMAS). Two stable isotope systems were evaluated separately: boron (10B:11B) and magnesium (24Mg:25Mg:26Mg). Their isotope amount ratios were estimated by monitoring their absorption spectra in-situ generated monohydrides. The molecular absorption spectrum of a XH molecule (X= B or Mg) with n isotopes would be a linear combination of n isotopologue spectra and the amount of each component (isotope) could be calculated by a multivariate regression (n= 2 and 3 for B and Mg respectively). For the analysis of boron certified reference materials (CRM), the band 1→1 for the electronic transition X1Σ+ → A1Π was measured around wavelength 437.1 nm. Since boron has a memory effect in graphite furnaces, a combination of 2 % (v/v) hydrogen gas in argon, 1 % trifluoromethane in argon, an acid solution of calcium chloride and mannitol as chemical modifiers were used during the BH vaporization at 2600 °C. Partial least square regression (PLS) for analysis of samples was applied. For this, a spectral library with different isotope ratios for PLS regression was created. Magnesium does not have memory effect. Therefore, only 2 % of hydrogen in argon as gas modifier during vaporization at 2500 °C was employed for analysis of magnesium CRM. Absorption spectra of MgH for the X2Σ→A2Π electronic transition (band 0→0) were recorded around wavelength 513.45 nm. A similar PLS procedure to the BH was applied. Results for B and Mg CRM are metrologically compatible with those reported by mass spectrometric methods. An accuracy of 0.08 ‰ for B and 0.1 ‰ Mg was obtained as the average deviation from the isotope CRM. Expanded uncertainties with a coverage factor of k = 2 range between 0.10 - 0.40 ‰.zeige mehrzeige weniger

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Metadaten
Autoren/innen:Carlos Enrique Abad Andrade
Koautoren/innen:S. Florek, H. Becker-Ross, M.-D. Huang, Hans-Joachim Heinrich, Sebastian Recknagel, Jochen Vogl, Norbert Jakubowski, Ulrich Panne
Dokumenttyp:Posterpräsentation
Veröffentlichungsform:Präsentation
Sprache:Englisch
Jahr der Erstveröffentlichung:2017
Organisationseinheit der BAM:P Präsidium
1 Analytische Chemie; Referenzmaterialien
1 Analytische Chemie; Referenzmaterialien / 1.1 Anorganische Spurenanalytik
1 Analytische Chemie; Referenzmaterialien / 1.6 Anorganische Referenzmaterialien
P Präsidium / PST Präsidiale Stabsstelle
DDC-Klassifikation:Naturwissenschaften und Mathematik / Chemie / Analytische Chemie
Freie Schlagwörter:Boron isotopes; Graphite furnace; High-Resolution Continuum Source Molecular Absorption Spectrometry; Hydride; Isotope ratio; Isotopic shift
Themenfelder/Aktivitätsfelder der BAM:Analytical Sciences
Analytical Sciences / Spurenanalytik und chemische Zusammensetzung
Veranstaltung:FACSS / SciX Conference 2017
Veranstaltungsort:Reno, NV, USA
Beginndatum der Veranstaltung:08.10.2017
Enddatum der Veranstaltung:13.10.2017
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:07.12.2017
Referierte Publikation:Nein