You may find some useful information in the paper by Chivas et al (1993): Coupled stable-isotope and trace-element measurements of lacustrine carbonates as paleoclimatic indicators. In: Swart, P.K. et al. (eds) Climate Change in Continental Isotopic Records. Am Geophys Union, Geophysical Monograph 78: 113-121.
This work was done before the development of the gas bench and is based on a Kiel device but I suspect many of the issues the authors addressed will be relevant to you. Included are modifications to the Kiel system, including replacing borosilicate glass components (the acid reservoir) and the reaction thimbles with longer ones of silica (to reduce background trace metal contamination, especially of Ca), the requisite change to the stroke of the lifting piston, and preparation of pure H3PO4. The system then required no transfer of spent-acid from these thimbles for later ICP-AES or ICP-MS analysis, simply dilution aided by external vibration. Samples sizes used are down to 30 micrograms of CaCO3.
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf Of stableisotopes UCB
Sent: Saturday, 24 August 2013 10:14 AM
To: [log in to unmask]
Subject: [ISOGEOCHEM] running carbonates with Gas Bench II, Delta Plus XL
I have a request to set up for carbonate stable isotope analysis. We have a Gas Bench II, without trapping and concentration loops, and a Delta Plus XL available with the possibility of using a Delta V if necessary. I have not analyzed carbonates before. Samples will probably be in the 1mg size range. It seems that a good starting place would be to use manually added phosphoric acid to the carbonate sample
in flushed Exetainers. However, this would appear to generate about 2%
v/v CO2 in the Exetainer head space, when out Delta Plus XL saturates at about 0.3% v/v. Can we dilute with the Gas Bench?
I am also curious if the residual acidified sample can be used for ICP-OES analysis of Mg, Ca, Mn, Fe and Sr. Since this is not typically done I assume there is a problem with analyzing samples in a phosphoric acid matrix. Any information anyone has would be helpful. This later question on ICP is also being sent to the Plasmachem list, apologies for cross posting.
Does anyone have recommendations on procedures for this analysis? Any advice and/or literature on the subject would be useful.
Thanks in advance, Paul Brooks.
Mr. Paul D. Brooks, Spectroscopist,
Dept. Integrative Biology MC3140
1005 Valley Live Sceince Building,
UC Berkeley, CA 94720-3140.
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