Agilent ICP-MS Journal (March 2012 – Issue 49)

Importance of the Topic

The introduction of triple quadrupole collision/reaction cell technology marks a significant advance in inductively coupled plasma mass spectrometry (ICP-MS). By adding a first quadrupole mass filter before the reaction cell, the Agilent 8800 ICP-QQQ ensures that only the target analyte mass enters the cell, transforming reaction-mode performance into a widely applicable, reliable analytical tool for ultra-trace determinations and complex matrices.

Objectives and Overview

This collection of articles presents the hardware design, operating modes, and application studies of the Agilent 8800 Triple Quadrupole ICP-MS. Key objectives include demonstrating enhanced interference removal, quantifying challenging elements like selenium and phosphorus at part-per-trillion levels, and exploring novel MS/MS scan modes for reaction chemistry investigation.

Methodology and Instrumentation

The Agilent 8800 integrates two high-frequency quadrupole mass filters (Q1 and Q2) separated by an octopole collision/reaction cell (ORS3) with four gas inlets. In single-quad mode, Q1 functions as an ion guide for conventional ICP-MS operation. In MS/MS mode, Q1 isolates the analyte mass, and Q2 records the product or precursor ions after cell reactions. Flexible cell gas options include helium for collision, ammonia, oxygen, hydrogen, and O2/H2 mixtures. The instrument shares the robust plasma generator, sample introduction (including bio-inert kits), and software platform of the proven 7700 Series, with added dynamic range and optimized vacuum design.

Main Results and Discussion

• Hardware Performance: Single-quad mode on the 8800 shows a twofold sensitivity increase and fivefold background reduction versus the 7700.
• MS/MS Mode: Q1 rejects on-mass interferences, enabling direct quantification of 51V in 9.8% H2SO4 with a 0.13 ppt detection limit using NH3 cell gas.
• Neutral-Gain and Product/Precursor Ion Scans: Detailed mapping of reaction pathways improves cluster ion separation, exemplified by clean TiO+ and NH3 cluster spectra free from Ni, Cu, or Zn overlaps.
• On-line Isotope Dilution of Selenium: Using an 82Se spike and O2/H2 reaction gas, recoveries of 90–112% were achieved in certified reference materials despite rare-earth interferences.
• Analysis of Ultra-Pure Chemicals: Sub-ppt background equivalent concentrations for V, Cr, Ge, As in 20% HCl and for P, Ti, V in high-silicon matrices demonstrate reliable quantification in semiconductor-grade acids.

Practical Benefits and Applications

The 8800 enables trace and ultra-trace analysis in demanding applications such as semiconductor chemical quality control, environmental monitoring, speciation of toxic metals, and nanoparticle characterization. The MS/MS capability ensures consistent reaction chemistry regardless of sample composition, simplifying method development and enhancing data accuracy.

Future Trends and Applications

• Expansion of triple-quad ICP-MS into LC-ICP-MS, GC-ICP-MS, and field flow fractionation for advanced speciation and nanoparticle studies.
• Adoption of bio-inert sample paths and automated workflows for high-throughput QA/QC laboratories.
• Development of new reaction gas chemistries for isotopic tracer studies and challenging analytes.
• Integration with laser ablation and microflow interfaces for spatially resolved and ultra-low volume analyses.

Conclusion

The Agilent 8800 Triple Quadrupole ICP-MS redefines interference removal by precisely controlling ion populations entering and exiting the reaction cell. Its MS/MS functionality, versatile cell gas options, and shared 7700 Series platform deliver unmatched performance for complex matrices and ultra-trace determinations, establishing a new benchmark for ICP-MS applications.

References

• G. Centineo et al., Agilent Publication 5990-9171EN, 2011.
• A. Henrion, Fresenius Journal of Analytical Chemistry, 1994, 350, 657-658.