Enhanced Helium Collision Mode with Agilent ORS4 Cell

Significance of the topic

The removal of polyatomic interferences in single quadrupole ICP-MS is critical for accurate trace element analysis. Helium collision mode is widely applied due to its broad applicability and minimal reaction product formation. Enhancing this mode extends capabilities for low level measurements in complex samples.

Objectives and overview of the study

This work describes the performance improvements achieved by fitting an Octopole Reaction System (ORS4) to Agilent single quadrupole ICP-MS instruments and operating in an enhanced helium collision mode. The goals include improving interference removal and sensitivity for challenging analytes such as selenium and other elements affected by intense polyatomic backgrounds.

Methodology and instrumentation used

• Instrument Agilent single quadrupole ICP-MS with ORS4 collision cell
• Helium collision mode enhanced by a long high frequency octopole
• High cell gas flow rates to increase pressure
• Expanded bias voltage range to raise ion kinetic energy

Main results and discussion

The enhanced cell design produces a greater separation in the kinetic energy distributions of analyte and interfering ions. For selenium at mass 78 this yields a background equivalent concentration (BEC) of 2.66 ppt and a detection limit of 4.52 ppt using only helium. Similar improvements were observed for silicon phosphorus and sulfur. The enhanced mode rejects Ar2 interferences more efficiently while maintaining or improving analyte transmission. Complex real world samples benefit from consistent interference reduction without reactive gases.

Benefits and practical applications of the method

• Simplified single cell gas methodology eliminating the need for reactive gases
• Lower detection limits and BECs for key elements including Se Si P and S
• Broad applicability to multi element and variable sample matrices
• Access to confirmatory isotopes for quality assurance

Future trends and potential applications

Advances in CRC cell design suggest further improvements in collision mode performance. Integration with quadrupole ICP MS may expand to more complex matrices and additional analytes. Emerging applications include environmental monitoring food safety and clinical analysis where low ppt quantitation is critical.

Conclusion

Enhanced helium collision mode using the Agilent ORS4 cell provides superior interference removal and sensitivity in single quadrupole ICP MS. The method delivers ppt level detection for traditionally challenging elements without reactive gases. This approach streamlines workflows and meets demanding analytical requirements across diverse fields.

References

• Agilent Technologies Enhanced Helium Collision Mode with Agilent ORS4 Cell Agilent ICP MS Technology Brief November 2020 Publication 5994 1171EN