A New Design of Ion Lens and Collision/Reaction Cell for ICP-MS

Importance of the Topic

The removal of polyatomic interferences is a critical challenge in quadrupole ICP-MS, especially when analyzing complex, variable matrices. Effective interference control improves accuracy, lowers detection limits and ensures reliable multi-element analysis across diverse sample types.

Study Objectives and Overview

This work introduces a third-generation collision/reaction cell (ORS3) equipped with an optimized ion lens design and evaluates helium collision mode for broad-spectrum interference removal. The study compares no-gas, H2 and He modes across multiple acid-based matrices to demonstrate the cell’s performance.

Methodology

Ultratrace multi-element measurements were performed on the Agilent 7700 Series ICP-MS with the new ORS3 cell. Seven distinct blank sample matrices, including mixed nitric, hydrochloric and sulfuric acids with isopropanol, were analyzed in three cell modes. Apparent element concentrations in blanks quantified residual interferences and blank equivalent concentrations.

Used Instrumentation

• Agilent 7700 Series ICP-MS
• Third-generation ORS3 collision/reaction cell
• ShieldTorch ion source for narrow energy spread

Main Results and Discussion

• No-gas mode exhibited extensive polyatomic overlaps on nearly every mass in complex matrices.
• H2 collision mode removed some reactive interferences but created new overlaps and failed to eliminate unreactive polyatomics; sensitivity losses occurred for elements like Cu.
• He collision mode achieved consistent, low-level blanks for all 14 tested analytes, indicating complete removal of polyatomic interferences without new by-products.
• Key ORS3 design improvements (18% longer rods, 15% smaller diameter, 16% higher gas pressure, 20% higher RF frequency and larger kinetic energy discrimination step) underlie the effective separation of low-energy polyatomics.

Benefits and Practical Applications

He mode ICP-MS with ORS3 offers:

• Robust interference removal across unknown and variable sample types
• Predictable sensitivity due to inert gas operation
• Improved data integrity for QA/QC, environmental, food and industrial analyses

Future Trends and Possibilities

Ongoing developments may include further miniaturization of cell components, adaptive gas control strategies and integration of automated method optimization. Expansion of inert gas collision modes to new mass ranges and coupling with high-throughput workflows will extend applicability to emerging fields such as nanoparticle characterization and isotope ratio analysis.

Conclusion

The ORS3 collision cell with helium collision mode delivers superior polyatomic interference removal compared to no-gas and H2 modes. By combining high gas pressure, focused ion optics and a significant energy discrimination step, the system ensures accurate, low-blank multi-element analysis in challenging matrices.