Kiel IV-MAT 253 routine sample amounts are ~10-100 µg weight equivalent CaCO3. Samples significantly larger than ~200 µg weight equivalent CaCO3 should be subsampled to ensure efficient analysis without fractionation. Samples smaller than 5 µg CaCO3 measured with the Kiel IV-MAT 253 do not yield useful isotope ratio data.
Weights of foraminifera samples may be estimated. For example, if shells for a given taxa are known to weigh ~20 µg each, then instead of weighing each sample individually, 3 shells may be simply collected for each carbonate isotope sample, yielding ~60 µg CaCO3 per sample. Precise knowledge of individual sample weight is not important for accurate carbonate isotope ratio analysis.
Note that fine-grain samples of drilled, ground, or powdered material will typically be subsampled at UCSC SIL by weighing prior to analysis. Quantitative recovery of fine-grain material from vials after shipment is practically limited. If fine grained material is not sample limited, please ship ~1 mg more sample than is necessary for analysis. This amount may be estimated visually, as this aliquot will be subsampled precisely at UCSC SIL. If fine-grain material is sample limited, as is typical for drilled otolith or speleothem, please see instructions for preparing samples in aluminum foil envelopes in the description of sample packaging below.
For bulk marine sediments, ~100 µg is often a reliable sample size. For samples with unknown wt%CaCO3, this sample amount yields enough CaCO3 for a carbonate isotope ratio measurement for any sample >10 wt%CaCO3 without compromising the efficiency either carbonate acidolysis or the dynamic range efficient and accurate measurement by the Kiel IV. Samples with <10 wt%CaCO3 require appropriately larger samples. Please include information about wt%CaCO3 if known. As discussed above, please ship ~1 mg more sample than is necessary for analysis
For well-preserved apatite from tooth enamel, bone, or dentine to be measured with the Kiel IV, a reliable sample size range is 700-800 µg of treated material. This amount usually represents an optimum of CO3 yield versus efficient sample acidolysis. Fossil samples may require a larger sample size. Sample up to ~1500 µg can be measured efficiently.