Addressing the Hydrogen sulfide gas contamination to your carbonate
samples.... try Silver Phosphate trap:
Depending on the amount of H2S gas to be removed and the number of
samples, as well as your sample prep system ( in your case I assume
you have a basic vacuum line), try to use about 10g of Silver
Phosphate (Aldrich Chem. Co., part no. 33,738-2, 25g bottles, light
sensitive) in a glass vacuum tube with a suitable tap.
Simply freeze the contaminant CO2 gas into this tube, allow it to come
to the room temp for few minutes and than transfer the now cleaned CO2
into your sample tube.
Other suitable methods might be, as you have mentioned, lead acetate,
but also lead oxide, n-pentane or a GC.
Hope this helped!
Isotope & Organic Geochem Lab.
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