Measuring Cadmium in Water

Importance of the Topic

Cadmium contamination in drinking water poses significant health risks and arises from sources such as galvanized pipe corrosion and cadmium-containing solders. Ensuring accurate, sensitive detection of cadmium at low microgram-per-liter levels is essential for compliance with World Health Organization guidelines and various international standards.

Objectives and Overview of the Study

This study demonstrates an optimized graphite furnace atomic absorption spectrometry (GFAAS) method for cadmium measurement in water. Using intelligent software tools, the work aims to automate parameter selection, improve sensitivity, and reduce effort in method development while meeting or exceeding regulatory requirements.

Methodology and Instrumentation

The analysis employed an Agilent 240Z AAS system with transverse Zeeman background correction, featuring:

• Agilent GTA 120 graphite tube atomizer and pyrolytic Omega platform
• Agilent PSD 120 autosampler with Tube-Cam video alignment and an extraction/LED fume removal accessory
• Hollow cathode lamp at 228.8 nm, 0.5 nm slit width, 4 mA lamp current, peak area mode
• 99.99 % argon as inert gas
• Chemical modifier: NH₄H₂PO₄ (5 g/L) and Mg(NO₃)₂ (10 g/L)

Method optimization used the SRM Wizard, a chemometric Surface Response Methodology tool integrated into the instrument software, to determine optimal drying, ashing, and atomization temperatures with minimal user intervention (three clicks).

Key Results and Discussion

Using the optimized conditions, the study found:

• Characteristic concentration: 0.035 µg/L (peak area)
• Characteristic mass: 0.57 pg
• Instrument detection limit (20 µL): 0.011 µg/L
• Recovery for standard reference material (0.50 µg/L): 98.1 %
• Recovery for spiked bottled water (1.0 µg/L): 101.7 %

The optimized ash temperatures were approximately 570 °C for the standard and 568 °C for the sample; atomization temperatures were around 1533 °C and 1577 °C, respectively. The close agreement indicates robustness of the modifier mixture and the SRM optimization approach.

Benefits and Practical Applications

The automated optimization reduces method development time and user error, while the Zeeman background correction and fume extraction improve signal stability and safety. Lower argon consumption and extended tube lifetime contribute to cost efficiency. This method is well suited for routine drinking water analysis in environmental and regulatory laboratories.

Future Trends and Opportunities

Advances in software-driven optimization and real-time monitoring are expected to further streamline GFAAS workflows. Integration with laboratory information management systems and expanded chemometric models may allow multi-element analysis and adaptive calibration strategies. Ongoing improvements in tube coatings and gas management could enhance sensitivity and reduce operational costs.

Conclusion

The optimized GFAAS method on the Agilent 240Z platform delivers high sensitivity, reliable recoveries, and automated parameter selection for cadmium in water. It offers a cost-effective and user-friendly solution for laboratories requiring compliance with global drinking water standards.

References

1. World Health Organization 2011, WHO/SDE/WSH/03.04/80/Rev/1 – Cadmium in Drinking-water
2. Optimizing GFAAS ashing and atomizing temperatures using Surface Response Methodology, Agilent publication number 5991-9156EN