Development and characterization of a new in-house reference material for stable carbon and oxygen isotopes analyses

Author(s)

Crivellari, Stefano ^[1] ; Viana, Patricia Junia ^[1] ; Campos, Marilia de Carvalho ^{[1, 2]} ; Kuhnert, Henning ^[3] ; Machado Lopes, Alyne Barros ^[2] ; Cruz, Jr., Francisco William da ^[2] ; Chiessi, Cristiano Mazur ^[1]

Affiliation

^[1] Univ Sao Paulo, Sch Arts Sci & Humanities, Sao Paulo - Brazil

^[2] Univ Sao Paulo, Inst Geosci, Sao Paulo - Brazil

^[3] Univ Bremen, MARUM Ctr Marine Environm Sci, Bremen - Germany

• Document type: Journal article
• Source: Journal of Analytical Atomic Spectrometry; v. 36, n. 6, p. 1125-1134, JUN 1 2021.
• Web of Science Citations: 0

Abstract

The precision and accuracy of an isotope ratio mass spectrometry (IRMS) laboratory and the quality of its scientific output directly depend on the quality of the reference materials used for calibration. However, the specification and characterization of the in-house reference material and analytical details of the laboratory routine are rarely published or accompanied in the scientific studies that rely on IRMS measurements. Here we describe the development of a new in-house laboratory reference material (SHP2L) used for normalizing measurements of carbon and oxygen stable isotopes (delta C-13 and delta O-18) of carbonate material at the newly formed Paleoceanography and Paleoclimatology Laboratory (P2L). The analytical setup consists in a Thermo (TM) MAT253 coupled to a Thermo (TM) Kiel IV carbonate device. The equipment is stable in the long term (precision better than 0.1 parts per thousand over a two-months period) and ensures analytical precision (sample-to-sample, 1 sigma) better than 0.04 parts per thousand for delta C-13 and 0.07 parts per thousand for delta O-18, down to masses of 30 mu g. The material chosen for the production of the SHP2L is a calcium carbonate plate (about 800 cm(3) to 2.1 kg) from the German Jurassic Solnhofen Formation. The isotopic homogeneity was assessed by taking 25 regularly spaced samples from both sides of the plate. The standard deviation of these samples were less than 0.11 parts per thousand for both delta C-13 and delta O-18. The plate was then fragmented, ground and sieved to isolate the 63-124 mu m grain-size fraction. The chemical and mineralogical quality of the SHP2L was established by X-ray fluorescence and diffraction respectively, which show predominantly calcium carbonate, with negligible amounts of other constituents in purely calcite mineralogical phase. Batches of ca. 50 samples from the 63-124 mu m fraction were analyzed for delta C-13 and delta O-18 in three laboratories. Established SHP2L isotopic composition is -0.766 +/- 0.042 parts per thousand for delta C-13 e -5.741 +/- 0.064 parts per thousand for delta O-18. The SHP2L proved to be a homogeneous reference material for delta C-13 and delta O-18 stable isotopes analyses. The methodological template for production of a carbonate working standard is illustrated herein. The SHP2L is available for distribution upon request to the first author. (AU)

• FAPESP's process: 16/10242-0 - Occurrence and impact of the mega-South Atlantic Convergence Zone over the eastern South America during the last glacial period: a paleoceanographic approach
• Grantee: Marília de Carvalho Campos Garcia
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 20/06534-0 - Abrupt changes in the deep Western Tropical Atlantic Ocean during the last two glacial periods
• Grantee: Stefano Crivellari
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 12/17517-3 - Response of the Western Atlantic Ocean to changes in the Atlantic meridional overturning circulation: from millennial to seasonal variability
• Grantee: Cristiano Mazur Chiessi
• Support Opportunities: Research Program on Global Climate Change - Young Investigators
• FAPESP's process: 18/15123-4 - Past perspectives on tipping elements of the climate system: the Amazon Rainforest and the Atlantic Meridional Overturning Circulation (PPTEAM)
• Grantee: Cristiano Mazur Chiessi
• Support Opportunities: Research Grants - Research Program on Global Climate Change - Young Investigators - Phase 2