Ultra-fast ICP-OES determination of trace elements in water, conforming to US EPA 200.7 and using next generation sample introduction technology

Importance of the Topic

The accurate determination of trace elements in water is essential for environmental compliance, public health protection and industrial quality control. Adopting efficient sample introduction methods while conforming to US EPA 200.7 guidelines addresses the need for high throughput, reliable detection limits and robust quality assurance in routine water analysis.

Objectives and Overview of the Study

This study evaluates the performance gains achievable by coupling the Agilent SVS 2 next-generation sample introduction system with an Agilent 720 Series simultaneous ICP-OES. The primary aim was to implement EPA Method 200.7 for 32 analytes in drinking and waste waters, achieve regulatory detection limits, maintain data quality, and more than double sample throughput compared with conventional systems.

Methodology and Instrumentation

The analysis employed:

• Agilent 720 Series ICP-OES with axially viewed plasma and custom CCD detector covering 167–785 nm
• SVS 2 sample introduction system featuring a high-speed positive displacement pump, software-triggered valve positions, and a fixed flow to the plasma
• SPS 3 autosampler and SeaSpray nebulizer with glass cyclonic spray chamber
• Operating conditions: 1.4 kW RF power, 15 L/min plasma gas, 1.5 L/min auxiliary gas, 0 s stabilization and rinse delays
• Calibration and QC solutions prepared per EPA 200.7 using multi-element standard mixes, reagent blanks, fortified blanks, interference check solutions and certified reference materials

Main Results and Discussion

Key findings included:

• Sample-to-sample time reduced from ~150 s (2.5 min) to 68 s, more than doubling throughput
• Continuous flow to the plasma eliminated high-speed to low-speed pump transitions, reducing stabilization delay to <10 s
• Method detection limits ranged from 0.1 ppb (Ag) up to 16 ppb (P), meeting or exceeding EPA requirements
• Linear dynamic ranges extended up to 1000 ppm for selected elements with calibration errors <10%
• Instrument performance check over six hours showed <2% drift for all 32 elements
• Analysis of NIST SRM 1643e, SRM 1640a and certified wastewater reference samples demonstrated recoveries within ±10% and low relative percent differences in duplicates
• Spectral interference checks confirmed the absence of significant interferences at the chosen wavelengths

Benefits and Practical Applications of the Method

The integration of SVS 2 and Agilent 720 ICP-OES delivers:

• Significantly higher laboratory productivity and sample throughput
• Enhanced plasma stability and reduced consumable wear
• Lower operating costs through reduced reagent and wash times
• Regulatory compliance with rigorous EPA 200.7 quality control protocols
• Versatility for environmental monitoring, contract labs and industrial QA/QC

Future Trends and Possibilities

Emerging developments may include further miniaturization of sample introduction, integration with automation and robotics, real-time monitoring with remote operation, and application of data analytics or machine learning for predictive maintenance and advanced method optimization. Expansion to complex matrices and coupling with complementary techniques could broaden the technology’s impact.

Conclusion

Implementing the Agilent SVS 2 with simultaneous ICP-OES under EPA 200.7 guidelines achieved more than a two-fold increase in throughput while maintaining or improving analytical performance, detection limits and data quality. This approach offers a robust, cost-effective solution for high-volume water analysis.

Reference

• D. Hoobin and E. Vanclay, Ultra-fast ICP OES determinations of soil and plant material using next generation sample introduction technology.
• S. Bridger and M. Knowles, A complete method for environmental samples by simultaneous axially viewed ICP-OES following US EPA guidelines.