Ultra-fast ICP-OES determination of trace elements in water, as per US EPA 200.7

Significance of topic

Monitoring trace metals in water is critical for protecting human health and ecosystems. Regulators enforce strict limits, driving environmental laboratories to balance high sample throughput, low operating costs, and robust analytical performance under US EPA Method 200.7 standards.

Objectives and study overview

This application study evaluates the Agilent 5100 Synchronous Vertical Dual View (SVDV) ICP-OES coupled with the SVS 2+ switching valve and SPS 3 autosampler for ultra-fast, multi-element analysis of water certified reference materials (TMDW-A and TMDW-B) in compliance with EPA 200.7. The goal is to demonstrate accelerated analysis times, reduced argon consumption, and reliable trace-level detection.

Applied instrumentation

• ICP-OES: Agilent 5100 SVDV with Dichroic Spectral Combiner (DSC) and VistaChip II CCD detector
• Sample introduction: Seaspray nebulizer, cyclonic spray chamber, 1.8 mm injector torch
• RF generator: solid-state RF at 27 MHz
• Autosampler and valve: SPS 3 with SVS 2+ (7-port positive-displacement valve; bubble injector)

Methodology

Standards were prepared from single-element stock solutions in 1 % HNO₃. Certified Reference Materials (TMDW-A and B) were analyzed in a single run. The SVS 2+ valve limits sample uptake and rinse delays, enabling a 58-second cycle time per sample. The DSC selects radial measurement for high-abundance elements (Na, K) and axial measurement for trace elements, combining signals in one reading.

Results and discussion

• Linear dynamic range: eight orders of magnitude, with upper concentration limits up to 500 ppm for Mg and Na
• Method detection limits: sub-ppb sensitivity for many metals (e.g., Be 0.04 µg/L, Cd 0.2 µg/L, Pb 1.9 µg/L)
• CRM recoveries: 94–109 % across 26 elements in both TMDW-A and TMDW-B
• Throughput and efficiency: 58 s/sample and <21 L argon/sample (50 % reduction vs. conventional DV)
• Long-term stability: over 12 h, all elements remained within ±10 % recovery and <1.3 % RSD

Benefits and practical applications

The integrated SVDV approach streamlines environmental compliance testing by:

• Cutting analysis time by up to 55 %
• Halving argon usage and per-sample costs
• Ensuring consistent torch alignment and minimal user intervention
• Delivering reliable detection of ppb-level analytes alongside %-level major ions in a single measurement

Future trends and applications

Advances such as the fully integrated Advanced Valve System (AVS) promise further gains in throughput and precision. Ongoing innovations in plasma source design and spectral deconvolution may extend this methodology to complex matrices beyond water, including sludge, soils, and industrial effluents.

Conclusion

The Agilent 5100 SVDV ICP-OES with SVS 2+ and SPS 3 autosampler effectively fulfills EPA 200.7 requirements while maximizing laboratory productivity. It achieves rapid cycle times, significant cost savings, and robust trace element detection, making it a powerful workhorse for environmental monitoring.

References

• US EPA Method 200.7, Revision 5 (40 CFR Part 136, Appendix B, Section 9.2.1)
• Agilent Technologies, Publication 5991-4821EN, October 25, 2017