Multi-element analysis of surface and waste waters using triple quadrupole ICP-MS with prepFAST autodilution

Importance of the Topic

Environmental monitoring of surface and waste waters demands sensitive, robust and high-throughput multi-element analysis to enforce legislation and protect human, animal and plant health. Traditional single-quadrupole ICP-MS methods often struggle with spectral interferences and require multiple techniques to cover different elements. Triple-quadrupole ICP-MS combined with automated inline dilution addresses these challenges by enabling interference-free, comprehensive screening of all relevant trace and matrix elements in a single run.

Goals and Overview of the Study

The primary aim was to demonstrate routine automated multi-element analysis of 50 environmental water samples (25 surface waters, 25 waste waters) using Thermo Scientific iCAP TQ ICP-MS coupled to an Elemental Scientific prepFAST autodilution system. The study evaluated the method’s accuracy, precision, limits of quantification and compliance with EU ISO 17294, Flemish environmental regulations (VLAREM) and the WAC performance criteria.

Methodology and Instrumentation

All analyses were performed on an iCAP TQ ICP-MS operated via Qtegra ISDS Software. The system was tuned in single- and triple-quadrupole modes using the Reaction Finder assistant to optimize quadrupole and collision/reaction cell parameters. Reactive gases (O2, NH3) and helium KED modes were selected per isotope to eliminate polyatomic interferences and extend dynamic range. Samples were digested (HCl/HNO3 hot block) per NBN-EN-ISO 15587-1, then automatically diluted 1:5 by prepFAST. Calibration employed multi-element standards over µg·L–1 to mg·L–1 levels with Rh internal standard (20 µg·L–1).

Main Results and Discussion

• Accuracy: Laboratory control samples (n=6) yielded recoveries of 89–114% (WAC criterion 80–120%).
• Reference materials (NIST SRM 1640a, SPS-SW2) showed recoveries of 85–104% and RSDs generally <5%, confirming interference removal.
• Limits of quantification met 30% of environmental quality standards for 65 of 68 elements; minor exceptions (Ag, Be, Tl) are addressable by further optimization.
• Dynamic range spanned >8 orders of magnitude (0.01–1×10^6 µg·L–1) with consistent internal standard stability (80–110% over 130 samples in 7 hours).

Benefits and Practical Applications of the Method

• Simultaneous determination of 68 regulated and priority elements from a single sample preparation.
• Automated inline dilution reduces human error, frees operator time and ensures unattended high-throughput analysis.
• Triple-quadrupole technology provides routine removal of doubly charged and polyatomic interferences, improving confidence in critical analytes (As, Se, Cd, Hg).
• Compliance with multiple international guidelines in drinking, surface and waste water testing.

Future Trends and Possibilities

Incorporation of multiple internal standards (6Li, Sc, Ge, Ir) across the mass range will enhance method robustness and accuracy. Further integration with laboratory information management systems (LIMS) and advanced data analytics (machine-learning-driven interference prediction) can streamline method development. Expansion to other matrices (soils, sediments, biowastes) and isotopic ratio applications (e.g., uranium isotopes) will broaden environmental and geochemical use cases.

Conclusion

Triple-quadrupole ICP-MS with automated inline dilution delivers rapid, accurate and interference-free multi-element analysis of environmental waters. The iCAP TQ ICP-MS method meets regulatory requirements for sensitivity, precision and throughput, making it an ideal solution for routine monitoring and compliance laboratories.

References

• Compendium for analysis of water based on ISO 17294 (WAC performance criteria version 11/2018).
• Vlarem II Appendix 4.2.5.2: Reporting limits and LOQmax for waste water.
• Vlarem II Appendix 2.3.1: Surface water quality standards.
• European Commission 2009/90/EC: 30% EQS criterion.
• Vlarem II Appendix 2.4.1: Minimum background and threshold values.
• Vlarem II Appendix 4.2.5.2: LOQmax for groundwater and drinking water.