Samples submission guidelines (stable carbon and oxygen isotope analyses)

This page contains the details for commissioning commercial stable carbon and oxygen isotope analyses at the Paleoceanography and Paleoclimatology Laboratory, School of Arts Sciences and Humanities at University of Sāo Paulo, Brazil.

The terms of use present in this document are generally binding for all users.

In principle P2L accepts samples from researchers and scientists from any institution. However, we reserve the right to deny service at discretion of the head of the laboratory.

Sample preparation

Please beware we only accept dry carbonate, aragonite, dolomite samples, in granular or powdered form. This includes foraminifera, ostracods, corals, mollusks, otoliths, coccolithophores and calcareous dinoflagellates, speleothems, bulk sediment. The minimum carbonate mass for an analysis is 30 μg granular and 70-100 μg for powder material (powder material tends to adhere to the vial walls). Higher sample amount ensures a better measurement quality and the possibility to repeat the analyses if necessary. There is no upper limit in sample mass, the lab operator will take care of analyzing the right amount. We will not wash, sonicate or crush the sample. Foraminiferal samples should be hand picked by the user and it is important to avoid tests with visible adhered materials, re-crystallization or that are fragmented. The selected tests should be stored preferably in micro paleontology slides. If it is not possible to use micro paleontology slides, please use microtubes (e.g. Eppendorf microtube) of 0.5 or 1.5 ml (with conical bottom). Please do not send glued specimens samples, these cannot be accepted by the mass spectrometer.

In general please make sure your samples are clearly and uniquely identified. Please include in the labeling the following information:

  • ID number, which should be defined by the user and should preferably be a sequential number
  • Species
  • Size fraction
  • Number of tests and the sample mass (the latter, when available)
  • Samples comments

Mineralogy is assumed to be calcite if no mineralogical phase is specified in the sample list. If samples are of another mineralogical phase the conversion between different fractionation factor (α) with the phosphoric acid reaction is the following (Kim et al, 2007, Chemical Geology).

δ18O_phase1 = ((α_phase2/α_phase1)*((δ18O_phase2/1000)+1)-1)*1000

Acknowledgments

When results produced at P2L are being published, proper acknowledgment must be included in the “Materials and Methods” section of the publication using the following template: 

Analyses on (your samples) for determination of δ13C and δ18O isotopic composition were performed at the Paleoceanography and Paleoclimatology Laboratory, School of Arts Sciences and Humanities at University of Sāo Paulo, Brazil. The laboratory is equipped with a Thermo Fisher Scientific™ MAT253 isotope ratio mass spectrometer (IRMS) coupled with a Thermo Fisher Scientific™ Kiel IV carbonate preparation device. The details on the laboratory analytical setup and performance are described in Crivellari et al. (2021). The IRMS measures the isotopic composition of the CO2 developed by the reaction between the sample carbonate and orthophosphoric acid at 70°C. Measurements were calibrated against repeated measurements of SHP2L reference material which is used as internal working standard (Crivellari et al., 2021). SHP2L is in turn calibrated against international reference material NBS19 and values are anchored to the Vienna Pee Dee Belemnite (VPDB) scale. Analytical precision was better than (please use the value informed by P2L) ‰ for δ13C and (please use the value informed by P2L) ‰ for δ18O (±1 s, n = 30).

Reference
Crivellari, S., Viana, P.J., Campos, M.C., Kuhnert, H., Barros, A., Cruz Júnior, F.W., Chiessi, C.M., 2021. Development and characterization of a new in-house reference material for stable carbon and oxygen isotopes analyses. Journal of Analytical Atomic Spectrometry. DOI: 10.1039/D1JA00030F.

Sample volume

The minimum number of samples is 30. There is no upper limit in the number of samples you wish to submit. However, above 400 samples might result in additional waiting time.

Time expectancy

Typically, we have a weekly throughput of about 100 samples per week. To this must be added the time it takes to receive the samples and to confirm the allocated time window. Generally speaking, you can expect to have your results within a month or two from the first solicitation of the service.

Commissioned work

We will be glad to analyze your samples. Please get in touch with us at p2l-each@usp.br or check https://uspmulti.prp.usp.br/public/centrais/173 for more information.