Agilent 9500 ICP‑QQQ with m‑Lens for Ultratrace Analysis of High‑Purity Reagents

Significance of the topic

Controlling ultratrace metal contaminants in high-purity reagents and metal matrices is critical for semiconductor manufacturing, advanced materials characterization, and quality assurance workflows. Analytical methods that reliably deliver sub-ppt detection limits while remaining robust under demanding conditions (e.g., hot plasma) are essential to prevent yield loss, ensure product quality, and support traceability in regulated environments.

Objectives and study overview

This application note evaluates the Agilent 9500 Triple Quadrupole ICP‑MS (ICP‑QQQ) equipped with the optional m‑lens and Dual‑Cell System (DCS) for ultratrace analysis of semiconductor-grade reagents. Using instrument preset methods developed for ultrapure water (UPW) and concentrated acid matrices, the study tested performance for 1% HNO3 and 9.8% H2SO4, aiming to demonstrate sub-ppt detection limits (DLs), low background equivalent concentrations (BECs), and reliable interference control under hot plasma operating conditions.

Methodology

The workflow and analytical approach included:

• Sample preparation: UPW, Tamapure-AA-10 HNO3 diluted to 1% and Tamapure-AA-100 H2SO4 diluted to 9.8% (w/w%).
• Calibration: Multi-point external calibration in matrix-matched standards at 0, 5, 10, 20, and 30 ng/kg (ppt).
• Detection limit and BEC calculation: DLs = 3 × SD of blank signals; BECs = mean blank signal ÷ calibration slope; derived from five replicate blank measurements (n = 5).
• Tuning and interference control: Preset autotuned parameters (makeup gas flow and Omega lens voltage) to stabilize oxide formation (CeO/Ce ~1–3%). Five operational tune modes were used: no gas, Advanced Helium Mode (AHM), O2, NH3, and H2. Special Zn and Pt tunes were prepared for H2SO4 to optimize performance for those analytes.
• Interference mitigation: Use of the Dual‑Cell System with reaction/collision gases and AHM to remove argon- and matrix-derived polyatomic interferences (e.g., sulfur dimer interferences on Zn isotopes in H2SO4).

Instrumentation used

Key instruments and sample introduction components reported in the study:

• Agilent 9500 ICP‑QQQ with optional m‑lens (extraction‑Omega lens assembly) and Dual‑Cell System (DCS).
• Agilent I‑AS autosampler and OpenLab ICP‑MS software v1.1 for control and data acquisition.
• Sample introduction: MicroFlow PFA nebulizer with I‑AS probe (self-aspirating ≈200 µL/min), temperature‑controlled quartz spray chamber, and quartz torch with 2.5 mm i.d. injector.
• Interface hardware: Platinum‑tipped sampler cone (Cu base) and platinum‑tipped skimmer cone (Ni base) configured for m‑lens operation.

Results and discussion

The study demonstrated strong analytical performance for both 1% HNO3 and 9.8% H2SO4 matrices:

• Calibration linearity: All target elements showed excellent linearity (r > 0.99) across the calibration range.
• Detection limits and backgrounds: Sub-ppt DLs and low BECs were achieved for most analytes in both matrices, confirming the method’s sensitivity for ultratrace impurity control.
• Zn in H2SO4: A highlighted result was Zn measurement in 9.8% H2SO4—typically challenging due to 32S32S/32S34S/34S34S polyatomic interferences. Using AHM with the DCS and a Zn-specific tune, the method achieved a DL of 0.64 ppt and a BEC of 0.89 ppt, illustrating effective interference suppression even under hot plasma.
• Operational stability: Preset autotuning of makeup gas and Omega lens voltage produced a stable CeO/Ce ratio (≈1–3%), reflecting controlled oxide formation beneficial for reproducibility in ultratrace work.

Benefits and practical applications

The presented approach offers several practical advantages for laboratories performing ultratrace analysis:

• Accessible ultratrace capability: Preset methods simplify setup for labs transitioning to sub-ppt analysis while preserving robust interference control via DCS and gas modes.
• Versatility across matrices: The m‑lens and DCS combination delivers low backgrounds for both low-matrix reagents and metal-rich digests, enabling a single platform for diverse sample types.
• Reproducibility and robustness: Autotuned operating parameters and a stable sample introduction system support reproducible DLs and BECs under hot-plasma conditions.

Future trends and potential applications

Emerging directions and uses for this capability include:

• Broader adoption of triple-quadrupole ICP-MS in semiconductor manufacturing QC for routine sub-ppt impurity monitoring of process chemicals.
• Expanded use in high‑purity metal and materials analysis where hot plasma operation and matrix robustness are required.
• Further method refinement with tailored gas chemistries and isotopic strategies to extend low-background measurements to additional problematic analytes and complex matrices.
• Integration with automated sample preparation and data workflows to increase throughput while maintaining ultratrace sensitivity.

Conclusion

The Agilent 9500 ICP‑QQQ with optional m‑lens and Dual‑Cell System, operated with preset UPW and H2SO4 methods, delivers sub- or single-figure ppt detection limits and low background equivalent concentrations for a broad set of elements. The combination of dedicated tune modes (including AHM for Zn), reaction/collision gases, and autotuned ion optics enables reliable ultratrace impurity analysis under hot-plasma operating conditions, providing a practical and robust solution for laboratories requiring high-sensitivity, low-background measurements.

References

1. Sugiyama N. Dual-Cell System (DCS) and Advanced Helium Mode (AHM). Agilent publication, 5994-8985EN.
2. Yamashita R. Analysis of High Purity Titanium Using an Agilent 9500 ICP-QQQ. Agilent publication, 5994-9024EN.
3. Sakai K.; Shimamura Y. Ultrapure Process Chemicals Analysis by ICP-QQQ with Hot Plasma Conditions. Agilent publication, 5994-4025EN.