Measuring Lead in Water

Significance of the Topic

Measuring lead in drinking water is essential to protect human health due to lead’s toxicity and the stringent regulatory limit of 10 µg/L set by the World Health Organization. Continuous monitoring ensures safe water supplies and compliance with global standards.

Objectives and Overview of the Study

This application brief demonstrates the development and automatic optimization of a graphite furnace atomic absorption spectroscopy (GFAAS) method for quantifying trace levels of lead in water. The focus is on leveraging integrated chemometric tools in Agilent instrumentation to streamline method setup and meet requirements of various international guidelines.

Methodology and Instrumentation

The analysis combined atomic absorption with a graphite furnace, utilizing advanced features of the Agilent 240Z series:

• Agilent 240Z Atomic Absorption Spectrometer with transverse Zeeman background correction
• GTA 120 Graphite Tube Atomizer (pyrolytic Omega platform)
• PSD 120 Programmable Sample Dispenser autosampler
• Extraction/LED accessory for efficient fume removal and precise capillary alignment
• Modifiers: ammonium phosphate (NH₄H₂PO₄) and magnesium nitrate (Mg(NO₃)₂) to stabilize lead during pyrolysis
• Reference materials and spiked water samples for validation

A Surface Response Methodology (SRM) wizard within the instrument software automated the optimization of ashing and atomization temperatures, aided by real-time video imaging (Tube-CAM) during the drying steps.

Main Results and Discussion

Chemometric optimization yielded nearly identical optimal conditions for both the certified reference material and the spiked sample, confirming the modifier mix’s suitability. Key performance indicators included:

• Characteristic concentration (peak area): 0.85 µg/L
• Characteristic mass: 13.9 pg
• Instrumental detection limit (20 µL sample): 0.15 µg/L
• Recovery of certified reference material: 100.1 %
• Recovery of 25 µg/L spiked water: 103.6 %

These outcomes demonstrate compliance with stringent drinking-water standards and highlight the method’s robustness.

Benefits and Practical Applications

The fully automated optimization process reduces development time and the level of operator expertise required. Additional advantages include:

• Enhanced sensitivity and precision via Zeeman background correction
• Reduced argon consumption and extended graphite tube lifespan
• Improved laboratory safety and usability through local fume extraction
• Cost-effective solution for routine water testing and regulatory compliance

Future Trends and Potential Applications

Ongoing advances in chemometric software and imaging technologies are expected to further simplify trace metal analysis. Anticipated developments include:

• Real-time data analytics for continuous monitoring of water quality
• Miniaturized and portable GFAAS systems for field applications
• Machine-learning–driven optimization for simultaneous multi-element analysis

Conclusion

The Agilent 240Z GFAAS system, featuring the Stabilized Temperature Platform Furnace (STPF), Tube-CAM, SRM wizard, and extraction/LED accessory, offers a robust, sensitive, and user-friendly approach to lead determination in water. Automated method optimization ensures reliable performance and regulatory compliance with minimal setup effort.

References

• World Health Organization 2011, WHO/SDE/WSH/03.04/09/Rev/1 – Lead in Drinking-water
• Agilent Technologies. Optimizing GFAAS ashing and atomizing temperatures using Surface Response Methodology. Publication 5991-9156EN