High-Speed Environmental Analysis Using the Agilent 7500cx with Integrated Sample Introduction System – Discrete Sampling (ISIS–DS)

Significance of the Topic

High-speed and reliable multi-element analysis of environmental samples is critical for regulatory compliance and resource monitoring. The integration of advanced sampling accessories with ICP-MS instrumentation addresses the growing demand for fast, accurate, and low-volume analyses.

Objectives and Study Overview

This study evaluates the performance of the Agilent 7500cx ICP-MS equipped with the newly configured Integrated Sample Introduction System–Discrete Sampling accessory in helium collision mode. The aim was to achieve USEPA-compliant analysis of over 30 elements in approximately 75 seconds per sample, with sub-ppb detection limits and effective interference removal.

Methodology and Instrumentation

A discrete sampling approach using a 300 µL sample loop and a high-speed peristaltic uptake pump was implemented with the Cetac ASX-520 autosampler. The tubing between the injection valve and the nebulizer was minimized to reduce dispersion, yielding a 15-second stabilization delay. Spectrum mode acquisition with three replicates was performed under helium collision cell conditions, avoiding the need for gas switching and enabling rapid run times.

Used Instrumentation

• Agilent 7500cx ICP-MS with Octopole Reaction System in helium collision mode
• Integrated Sample Introduction System–Discrete Sampling (ISIS-DS) accessory
• Cetac ASX-520 autosampler with 0.8 mm internal diameter probe
• Standard glass concentric nebulizer and spray chamber

Main Results and Discussion

The optimized method achieved a sample-to-sample time of 75 seconds and consumed 2.2 mL of sample per analysis. A sequence of 216 samples was completed in 4 hours and 29 minutes. Internal standard recoveries remained within ±10% across all injections, and calibration check recoveries stayed within ±5%, complying with USEPA Method 200.8 criteria. Analysis of NIST 1643e certified reference water showed recoveries within ±10% of certified values and relative standard deviations near 1% for most elements. Washout testing demonstrated greater than 99.9% signal reduction in the first rinse blank for all analytes, including high-matrix elements such as Na, Mg, Al, K, and Fe.

Benefits and Practical Applications

The ISIS-DS configuration offers ultra-high throughput with minimal sample volume, making it ideal for laboratories facing high analysis demands or limited sample availability. Integrated software control, reduced carryover risk, and low waste generation contribute to enhanced operational efficiency and data reliability in environmental, QA/QC, and industrial settings.

Future Trends and Applications

Future developments may include integration of multiple reaction gases for expanded interference control, use of hydrogen mode for ultra-trace elements such as Se, further automation of sample preparation workflows, and miniaturization of sampling accessories for on-site field measurements.

Conclusion

The reconfigured ISIS-DS accessory on the Agilent 7500cx ICP-MS enables rapid, accurate, and interference-free environmental analyses that fully comply with USEPA standards while significantly reducing sample and reagent consumption.

References

• Agilent Technologies, High-Speed Environmental Analysis Using the Agilent 7500cx with Integrated Sample Introduction System–Discrete Sampling ISIS–DS, Application Note 5990-3678EN, March 2009.