The Agilent 7700x/7800 ICP-MS Advantage for Drinking Water Analysis

Importance of the topic

The accurate determination of trace metals in drinking water is critical for public health, regulatory compliance and environmental monitoring. Polyatomic interferences commonly encountered in ICP-MS analyses can compromise detection limits and data quality. The introduction of an optimized collision/reaction cell (ORS) capable of universal interference removal simplifies method development and improves performance across a wide range of sample chemistries.

Study objectives and overview

This application note evaluates the performance of the Agilent 7700x/7800 Series ICP-MS equipped with the Octopole Reaction System (ORS) in helium collision mode for routine analysis of trace metals in drinking waters. Key goals include:

• Assessing the ease of operation under a single set of conditions without prior sample knowledge
• Demonstrating improved detection limits and interference removal, particularly for iron and selenium
• Verifying robustness over extended sequences of high-matrix samples

Methodology and instrumentation

The 7700x/7800 ICP-MS incorporates:

• An optimized ORS for helium collision mode, enabling universal removal of polyatomic interferences
• Improved ion lens design and a new detector, providing higher sensitivity and lower background
• One-click Plasma Setting and Expert AutoTune for fully automated, reproducible instrument optimization
• High Matrix Introduction (HMI) system for stable, long-term analysis of samples up to several hundred mg/L TDS

Calibration standards contained 1% HNO3 and 0.5% HCl to stabilize elements such as Ag, Sb and Hg. Helium mode effectively removed chloride-based interferences on As, Se, Cr and V without resorting to reactive gases.

Main results and discussion

Representative calibration demonstrated linearity (R² ~1.000) and low background equivalent concentrations, for example a 3.7 ppt BEC for vanadium after ClO+ removal. Method detection limits (MDLs) determined as three sigma of ten replicates under default plasma conditions include:

• Fe and Se MDLs below 20 ppt in helium mode
• Be and B MDLs around 5 ppt in no-gas mode
• Most other elements with MDLs between 2 and 15 ppt in helium mode

A continuous 11-hour sequence of 190 samples (municipal waters, two high-TDS mineral waters, and a diluted NIST 1643e reference) yielded:

• Average run time under 3.5 minutes per sample
• Continuous calibration validation (CCV) recoveries within ±10% of target values for all analytes
• Relative standard deviations below 5% for repeated analysis of reference water

Benefits and practical applications

The combination of ORS, advanced ion optics and detector delivers:

• Lower detection limits and improved interference removal without reactive gases
• Simplified method setup under a universal condition set
• High throughput with run times below four minutes per sample
• Enhanced robustness for high-matrix samples via HMI integration

These advantages support routine drinking water monitoring, regulatory compliance testing and broader environmental or industrial analyses without instrument reconfiguration.

Future trends and applications

Further developments may include:

• Expansion of reaction cell gases or modes for even more challenging matrices
• Integration of real-time data correction algorithms leveraging universal collision mode data
• Application of the same streamlined methods to complex environmental samples such as soils, sediments and sludges
• Automation enhancements to support fully unattended multi-sample workflows

Conclusion

The Agilent 7700x/7800 ICP-MS with ORS in helium mode provides a robust, high-sensitivity solution for trace metal analysis in drinking waters. Universal interference removal, low detection limits and simplified operation yield reliable data quality and high productivity. The system’s wide dynamic range and HMI capability ensure consistent performance across a variety of sample matrices without the need for reactive cell gases or complex corrections.

Reference

Steve Wilbur. Agilent 7700x/7800 Series ICP-MS Octopole Reaction System for Drinking Water Analysis. Agilent Technologies Application Note 5990-4315EN, July 2015.