Simple and Reliable Soil Analysis using the Agilent 7800 ICP-MS with ISIS 3

Importance of the Topic

Routine monitoring of heavy metal levels in soils and sediments is vital for environmental compliance and human health risk assessment. US EPA Method 6020A guides the determination of over 60 elements from major to ultratrace concentrations in complex environmental matrices. Analytical methods that deliver accurate multi-element data, robust long-term operation, and high sample throughput support regulatory decision-making and site remediation.

Objectives and Study Overview

The study aimed to demonstrate the performance of the Agilent 7800 ICP-MS, equipped with High Matrix Introduction (HMI), ORS4 collision cell (He mode), ISIS 3 discrete sampling, and SPS 4 autosampler, for the analysis of soils and sediments following EPA 6020A protocols. Key goals included:

• Verifying method detection limits for trace and major elements.
• Assessing calibration recovery and long-term stability over extended sequences.
• Evaluating accuracy with certified reference materials (CRMs) and matrix spikes.
• Maximizing sample throughput via discrete sampling and high matrix tolerance.

Methodology

Samples and calibration standards were prepared in 4% HNO3 (with 0.5% HCl for Hg stability) using Agilent environmental calibration mixes and single-element fortification. CRMs (NIST 1640a, river and estuarine sediments, soils A and B) were analyzed at undiluted, 10×, and 50× dilutions. ISIS 3 loaded 1 mL sample loops rapidly, separating uptake and data acquisition to halve cycle times. The ORS4 cell in He mode (4.3 mL/min) mitigated polyatomic interferences via kinetic energy discrimination. Method parameters were based on the EPA 6020 preset in MassHunter with auto-optimization of plasma and lens settings.

Instrumentation Used

• Agilent 7800 ICP-MS with High Matrix Introduction (HMI) and ORS4 collision/reaction cell.
• Integrated Sample Introduction System (ISIS 3) for discrete sampling.
• SPS 4 autosampler with large-bore sample probe.
• Agilent MassHunter software for method setup, autotuning, and QC monitoring.

Key Results and Discussion

Method detection limits ranged from 0.01–0.1 ppb for trace elements and 10–50 ppb for major elements in the analyzed solutions. Low level initial calibration verifications (LLICV) and initial calibration verifications (ICV) met ±30% and ±10% criteria, respectively. Over 389 analyses spanning 10 hours, internal standard recoveries remained within ±30%, demonstrating stable operation without drift. Continuing calibration verifications (CCVs) showed recoveries within ±10%, avoiding recalibration events. CRM recoveries were within ±10% of certified values for all applicable elements. Matrix spike recoveries in soil samples also fell within ±25%, with relative percent differences below 20%.

Benefits and Practical Applications

• High matrix tolerance via HMI and ORS4 He mode reduces the need for extensive dilution and frequent maintenance.
• Discrete sampling with ISIS 3 doubles throughput by overlapping rinse and analysis steps.
• Wide dynamic range (10 orders) supports quantification from ultratrace to major levels in a single run.
• Simplified method setup and QC tracking in MassHunter enhance lab productivity and data integrity.

Future Trends and Applications

Continued integration of automated sample introduction and robust interference removal will drive higher productivity in environmental, industrial, and geochemical laboratories. Advances in data analytics and remote monitoring are expected to streamline method development and real-time QC. Emerging reaction cell chemistries may further expand analyte coverage and reduce interferences.

Conclusion

The Agilent 7800 ICP-MS, combined with HMI, ORS4 He mode, and ISIS 3 discrete sampling, delivers reliable, high-throughput analysis of soils and sediments compliant with EPA 6020A. The system achieves low detection limits, robust stability, and accurate quantification across diverse matrices, reducing downtime and maintenance.

Reference

1. S. Wilbur et al., High-Speed Environmental Analysis Using the Agilent 7500cx with ISIS-DS, Agilent Technologies, 2009, 5990-3678EN.
2. K. Yamanaka, S. Wilbur, Maximizing Productivity for High Matrix Sample Analysis Using the Agilent 7900 ICP-MS with ISIS 3, Agilent Technologies, 2014, 5991-5208EN.
3. S. Wilbur, C. Jones, Simple, Reliable Analysis of High Matrix Samples According to US-EPA Method 6020A Using the Agilent 7700x ICP-MS, Agilent Technologies, 2010, 5990-5514EN.