ICP-MS Analysis of Trace and Major Elements in Drinking Water According to US EPA Method 200.8

Importance of the Topic

The reliable determination of trace and major elements in drinking water is critical for public health monitoring and regulatory compliance. ICP-MS has become the method of choice for multi-element analysis due to its sub-ppb detection limits, wide elemental coverage, and high throughput. US EPA Method 200.8 remains a cornerstone protocol for water quality testing, but its original requirements pre-date modern advances in collision/reaction cells and automated quality-assurance software. Integrating state-of-the-art instrumentation and real-time data monitoring can significantly improve productivity, robustness, and confidence in compliance data.

Objectives and Study Overview

This study evaluates the performance of the Agilent 7850 ICP-MS—equipped with an Octopole Reaction System (ORS 4), the ISIS 3 discrete sampling introduction system, and Intelligent Sequence QA/QC software—when applying EPA 200.8 for drinking water testing. The goals were to:

• Demonstrate method detection limits (MDLs) and instrumental detection limits (IDLs) under low-matrix tune conditions.
• Verify accuracy and precision through standard reference material (SRM) analysis and in-sequence QC checks.
• Assess plasma robustness and long-term stability over typical workday runs.
• Showcase automated, real-time QC monitoring to reduce manual data review and prevent out-of-specification reporting.

Methodology and Instrumentation

Samples comprised bottled mineral water and two independent tap water sources. Twenty-five analytes were measured, including all 21 elements required by EPA 200.8 plus Na, Mg, K, and Ca. Key method features:

• Instrument: Agilent 7850 ICP-MS with standard quartz torch, nickel sampling/skimmer cones, ORS 4 operated in no-gas mode (per SDWA constraints) and kinetic energy discrimination (KED) with helium for comparative runs.
• Introduction: ISIS 3 discrete sampling with 1 mL loop, MicroMist nebulizer, Scott spray chamber, SPS 4 autosampler.
• Calibration: Five-point calibration (0–100 µg/L for traces; up to 25 000 µg/L for majors) in 1% HNO₃ + 0.1 mg/L Au(III) matrix; multi-element stock standards and single-element Hg standard.
• Internal Standards: Online addition of Li, Sc, Ge, Rh, In, Tb, Lu, and Bi at 2 mg/L via narrow-bore tubing.
• Method Parameters: EPA 200.8 preset tuning, autotuned ion lens voltages, predefined correction equations for spectral overlaps, integration times optimized per isotope.
• QA/QC: Continuing calibration blank (CCB), continuing calibration verification (CCV) every 10 samples, lab fortified blanks (LFB), laboratory fortified matrix spike (LFM), and NIST 1643f SRM.

Main Results and Discussion

Instrument sensitivity and detection limits: IDLs for critical trace elements were typically an order of magnitude below EPA 200.8 thresholds (e.g., As 0.019 µg/L vs. 0.02 µg/L IDL requirement). MDLs met or exceeded regulatory criteria.

Plasma robustness and stability: Under low-matrix tune, the CeO/Ce ratio averaged 1.0–1.2%, indicating a highly energetic plasma. Internal standard recoveries in three water samples remained within ±10% over nine hours, requiring no retuning or recalibration.

Accuracy: Analysis of NIST 1643f produced recoveries between 98% and 106% for all certified elements. CCV recoveries stayed within ±10% acceptance limits throughout the sequence.

Matrix effects: LFM spikes in bottled water delivered recoveries of 93–108% for all elements, confirming minimal bias from the water matrix.

Automated QA/QC: Intelligent Sequence software flagged out-of-range QC checks in real time, applied predefined actions (e.g., reruns or batch abort), and generated individual sample reports. This reduced manual review time and eliminated overlooked failures.

Benefits and Practical Applications

• Regulatory Compliance: Meets US EPA 200.8 and 40 CFR Part 141 requirements for Safe Drinking Water Act monitoring without modification.
• High Throughput: ISIS 3 loop injection reduces sample cycle times, enabling routine analysis of hundreds of samples per day.
• Operational Simplicity: Preset tuning methods and autotune features simplify method setup for analysts.
• Robust Data Quality: Low CeO/Ce ratio and He KED mode (where permitted) suppress polyatomic interferences for accurate trace measurements.
• Real-Time QC: Automated detection of QC breaches and immediate corrective actions enhance laboratory efficiency and data integrity.

Future Trends and Applications

Advances in ICP-MS collision/reaction cell technology, smart software, and automation will drive further gains in water analysis. Potential developments include:

• Expanded use of reaction gases for improved interference removal in complex matrices.
• Integration of machine learning algorithms for predictive maintenance and data anomaly detection.
• Miniaturized, field-deployable ICP-MS systems for on-site water monitoring.
• Enhanced standardization of global regulatory protocols incorporating modern cell modes and software tools.

Conclusion

The combination of the Agilent 7850 ICP-MS with ISIS 3 and Intelligent Sequence software provides a turnkey solution for EPA 200.8 drinking water testing. High sensitivity, robust plasma performance, and automated QA/QC ensure reliable, compliant data with minimal analyst intervention. This workflow meets the demands of commercial and regulatory laboratories, delivering both productivity and confidence in drinking water quality assessment.

Reference

• United Nations. Global Issues: Water. https://www.un.org/en/global-issues/water
• Sakai T., McCurdy E. “Agilent 7900 ICP-MS simplifies drinking water analysis.” Agilent Technologies Publication 5991-4938EN.
• Creed J.T., Brockhoff C.A., Martin T.D. “Method 200.8 Revision 5.4.” US EPA, 1994.
• ISO 17294-2:2016. Water Quality – Application of ICP-MS – Part 2: Determination of Selected Elements including Uranium Isotopes.
• Kubota T. “Fast, Accurate Analysis of 28 Elements in Water using ISO Method 17294-2 for ICP-MS.” Agilent Publication 5994-2804EN.
• US EPA National Pollutant Discharge Elimination System (NPDES). https://www.epa.gov/npdes
• US EPA. “Summary of the Safe Drinking Water Act.” https://www.epa.gov/laws-regulations/summary-safe-drinking-water-act
• NIST Certificate of Analysis for SRM 1643f Trace Elements in Water. National Institute of Standards & Technology, 2015.