In the future, we will be trying to perform oxygen and carbon stable isotope analysis on algal-bryozoan reefal limestone samples and foraminifera collected from it. We have an IRMS at our disposal. I am interested in which is the standard procedure of sample preparation.
Identification and separation of foraminifera:
Mass Spectrometric Technique:
Auto-carbonate Device
Procedure for Isotopic Measurements:
Standard protocol is acid digest of milled / ground samples using water-free phosphoric or sulforic acid at a constant temperature of 25C (for your kind of samples) for 12 hours in exetainer (purged with dry N2 or He prior to addition of acid). Evolved CO2 is analysed for 13C and 18O composition by IRMS. You will need to analyse as part of your sample batch run 2 carbonate reference materials as scale anchors for 13C (e.g. NBS19 and IAEA-CO-9) and another reference carbonate to use in conjunction with NBS19 for 18O (e.g. NBS18).
This paper discusses the subject of reference materials and scale normalisation:
Article A guide for proper utilisation of stable isotope reference materials
Annex II of this book contains a generic sample prepration protocol for carbonate analysis by acid digest.
https://onlinelibrary.wiley.com/doi/book/10.1002/9781119080190
Wolfram Meier-Augenstein thank you very much for your detailed answer!
Tyanks. Just noticed a typo (I hate touch pads). Of course I meant sulfuric acid (H2SO4).
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