Fully automated water analysis by OMNIS

Significance of the Topic

Reliable assessment of water quality is essential for public health, industrial processes, and environmental monitoring. Key parameters such as electrical conductivity, pH, alkalinity, calcium and magnesium hardness inform treatment decisions and regulatory compliance. Automated titration systems streamline analysis, reduce operator variability, and enable high-throughput monitoring of drinking water.

Study Overview

This application note outlines a fully automated workflow using the OMNIS system for parallel determination of conductivity, pH, alkalinity, calcium hardness, magnesium hardness, and total hardness in tap water. The method was validated using 63 samples from a municipal water supply in Herisau.

Methodology and Instrumentation

No sample preparation was required. A 200 mL disposable beaker received 100 mL of tap water. Preconditioning of the conductivity cell was performed by three dips in the sample, followed by conductivity measurement. Subsequent pH measurement guided two DET titrations: first for alkalinity using 0.1 mol/L HCl, then for hardness using 0.1 mol/L EDTA after addition of a TRIS-acetylacetone masking solution.

Used Instrumentation

• OMNIS Professional Titrator with Pick&Place modules
• OMNIS Dosing and Titration Modules
• Peristaltic pump units and Dosinos
• 856 Conductivity Module with five-ring cell and Pt1000
• Combined calcium ion selective electrode and dAquatrode
• Digital measuring modules and ETFE stirring propellers

Main Results and Discussion

Across 63 replicate analyses the method demonstrated high precision and reproducibility

• Conductivity: mean 0.546 mS/cm, RSD 0.27%
• pH: mean 8.079, RSD 0.58%
• Alkalinity: mean 5.674 mmol/L, RSD 0.27%
• Calcium: mean 2.133 mmol/L, RSD 0.71%
• Magnesium: mean 0.814 mmol/L, RSD 1.77%
• Total hardness: mean 2.947 mmol/L, RSD 0.44%

The total automated sequence required approximately 4 hours 32 minutes for all parameters. Data consistency indicates suitability for routine quality control.

Benefits and Practical Applications

The fully automated OMNIS workflow offers

• Reduced analyst intervention and error potential
• Parallel analysis for increased throughput
• Integrated data logging for quality assurance
• Versatility across drinking water, environmental monitoring, and industrial QC

Future Trends and Potential Applications

Advances in automation and sensor integration will drive

• Remote monitoring with IoT-enabled titrators
• Enhanced data analytics and AI-guided method optimization
• Miniaturized flow-through systems for inline water treatment control
• Expansion to additional analytes such as trace metals and organic contaminants

Conclusion

The OMNIS automated titration system provides a robust, high-precision platform for comprehensive water quality analysis. Its modular design and parallel processing capabilities meet the demands of modern analytical laboratories and support proactive water management strategies.

Reference

OMNIS Titration Application Note T-205 Version 1, December 2018