Nu Instruments | Very Small Calcium Carbonate Sample Analysis with Perspective IRMS
This application note investigates the lower sample-size limit for carbonate isotope analysis using the Nu Carb and Perspective IRMS. It demonstrates linearity and precision across a 4–41 µg sample weight range.
This application note explores how small calcium carbonate samples can be analysed using the Nu Carb automated carbonate device coupled to the Perspective IRMS. A set of Nu Carrara marble and NBS-19 samples ranging from 4–41 µg was prepared and analysed.
Samples were reacted with phosphoric acid at 70 °C, and the evolved CO₂ was cryogenically transferred for dual inlet analysis. Very small samples around 5 µg produced low initial ion currents and were rejected under the reference gas settings used.
The remaining data showed strong linearity and precision across the tested range. For Nu Carrara marble, corrected δ¹³C and δ¹⁸O values remained consistent across grouped sample weights from 4–10 µg, 11–20 µg and 21–41 µg.
Key Takeaways:
- Investigates carbonate isotope analysis from 4–41 µg sample weights.
- Shows consistent CO₂ yield above 10 µg under the tested conditions.
- Demonstrates strong linearity and precision for very small carbonate samples.
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