Cool Plasma ICP-MS Internal Standardization with Enriched Isotopes
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Solution Overview
Problem
High temperature plasma conditions in ICP-MS can lead to errors in elemental quantification and sample degradation, while cool plasma conditions result in incomplete ionization and variance in ionization profiles, making standardization challenging, especially for heavy metals.
Innovation Solution
The method involves introducing an enriched stable isotope of a chemical species into a sample containing a non-enriched isotope to form a sample and standard mixture, which is then analyzed under cool plasma conditions in an ICP-MS, allowing for correlation of the ionization amount of the non-enriched isotope based on the determined ionization of the enriched isotope, ensuring accurate quantification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high temperature plasma conditions are used in ICP-MS, then complete ionization of sample elements is achieved, but errors in elemental quantification and sample degradation occur
Solution Approach 1:
The patent changes the plasma temperature parameter from conventional high temperature to cool plasma conditions (lower temperature), which prevents sample degradation and reduces spectral interference while maintaining adequate ionization for analysis. This parameter change resolves the contradiction by operating at an optimized temperature point that balances ionization completeness with measurement accuracy.
2Measurement precision
If cool plasma conditions are used in ICP-MS, then sample degradation is reduced, but incomplete ionization and variance in ionization profiles occur
Solution Approach 1:
The patent introduces enriched stable isotopes as internal standards that serve as intermediaries to monitor and correct for ionization variability. These isotopic standards co-ionize with the sample elements under cool plasma conditions, providing a reference that accounts for ionization efficiency variations and enables accurate quantification despite incomplete ionization.
3Measurement precision
If enriched stable isotopes are introduced as internal standards, then accurate quantification of non-enriched isotopes is enabled, but device complexity increases
Solution Approach 1:
The enriched stable isotopes serve as self-referencing internal standards that automatically monitor and correct for ionization variability without requiring external calibration standards or complex correction procedures. The isotopic standards self-correct for matrix effects and ionization efficiency changes, simplifying the overall measurement process despite the addition of the isotopic reference material.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables accurate quantification of non-enriched isotopes by maintaining consistent ionization profiles between standards and samples, reducing errors and contamination, and maintaining the integrity of the sample introduction system under cool plasma conditions.
Implementation Method 1
introducing the sample and standard mixture to an ICP-MS under cool plasma conditions... determining an ionization amount of the enriched stable isotope by the ICP-MS
Data Source
AI summary
A method for internal standardization of cool plasma ICP-MS using one or more enriched stable isotopes includes introducing an enriched stable isotope of a chemical species to a sample containing a non-enriched isotope of the chemical species to form a sample and standard mixture. In implementations, the enriched stable isotope is introduced via an inline syringe addition to a flow of a sample solution containing a non-enriched isotope of the chemical species to be analyzed. The method also includes introducing the sample and standard mixture to an ICP-MS under cool plasma conditions. The method also includes determining an ionization amount of the enriched stable isotope by the ICP-MS. The method further includes correlating an ionization amount of the non-enriched isotope based on the determined ionization amount of the enriched stable isotope.