Nu Instruments | Ion Counting Linearity in High Resolution ICP-MS
This application note evaluates the ion counting detector linearity of the Attom High Resolution ICP-MS using certified uranium standards. The study demonstrates accurate and precise isotope ratio measurements across a wide range of count rates and concentrations, highlighting the detector's suitability for demanding isotope ratio applications.
Detector linearity is essential for accurate quantification and isotope ratio analysis in ICP-MS. Non-linear detector response can introduce measurement bias, particularly when analysing samples that produce widely varying signal intensities.
In this study, certified uranium reference materials were analysed under both dry plasma and wet plasma operating conditions. Measurements covered count rates ranging from below 1,000 counts per second to over 4 million counts per second using the Attom fast peak jumping mode.
Results demonstrated excellent isotope ratio accuracy and precision across all concentrations tested. The measured ²³⁴U/²³⁸U and ²³⁶U/²³⁸U ratios remained consistent regardless of signal intensity, confirming that the detector maintains linear performance across a broad dynamic range.
Key Takeaways:
- Accurate uranium isotope ratios were maintained from low count rates to over 4 Mcps.
- Detector linearity was demonstrated beyond the recommended 3 Mcps operating limit.
- Suitable for high-precision isotope ratio measurements across varying sample concentrations.
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