Analysis of water samples and water constituents with Metrohm instruments

Significance of the Topic

Water quality underpins public health, ecosystem balance and industrial processes. Accurate, multi‐parameter analysis of major and trace water constituents—from pH and conductivity to trace metals and organic acids—is essential for regulatory compliance, pollution monitoring and process control. Advances in Metrohm analytical platforms enable comprehensive, automated workflows that integrate titrations, direct potentiometric measurements, ion chromatography (IC) and voltammetric methods to meet stringent detection limits and throughput requirements.

Objectives and Overview

This monograph presents a unified approach for routine and research‐level water analysis using Metrohm instruments. It covers:

• Physical parameters (temperature, pH, redox potential, conductivity, color, turbidity)
• Bulk/titrimetric indices (permanganate index, acid/base capacity, hardness, COD, Kjeldahl N, H₂O₂)
• Gaseous constituents (free/total chlorine, dissolved O₂ by Winkler and optical sensors, ozone)
• Inorganic ions by titration and IC (major anions/cations, oxyhalides, perchlorate, chromate, silicate, sulfur species, organic/weak acids)
• Trace metals by voltammetry (heavy metals, metalloids) using mercury‐film or gold‐film sensors
• Automation strategies (Inline Ultrafiltration/Dialysis, TitrIC flex, MISP, preconcentration)

Methodology and Instrumentation

Metrohm provides modular platforms:

• Titrators (e.g., 888/905 Titrando) with potentiometric sensors for pH, redox, conductivity and complexometric endpoints
• IC systems (Eco IC, Compact IC Flex, Professional IC Vario) coupled to conductivity or UV/VIS detectors and MS for multi‐ion analysis
• Voltammetric analyzers (884 Professional VA) with Multi‐Mode or scTRACE Gold electrodes for trace metal quantification
• Automation accessories (Inline Ultrafiltration, Inline Dialysis, intelligent Pick‐up/Preconcentration) for sample preparation
• UV Digester for sample digestion in trace metal and nitrogen determinations

Main Results and Discussion

Comprehensive validation demonstrates:

• High precision and reproducibility for pH (±0.01) and conductivity (±0.5% U) across temperature‐controlled measurements
• Robust titrations for hardness, alkalinity, COD and permanganate index with automated endpoint detection and <1% RSD
• IC determinations achieving ng/L detection for bromate, perchlorate, chromate and trace organic acids using PCR, MS or sequential suppression
• Voltammetric trace metal analyses with detection limits in the ng/L range (e.g., Pt 0.1 ng/L, Rh 0.5 ng/L, As 0.9 µg/L) using catalytic or stripping modes
• Automation examples (Inline Ultrafiltration, TitrIC flex II) reduce manual workload, prevent matrix interference and enable high sample throughput

Benefits and Practical Applications

• One‐stop solution: consolidation of titration, direct ISE measurement, IC and VA on single platforms
• Regulatory compliance: methods aligned with EN, ISO, US EPA and ASTM standards
• Flexible automation: MISP modules and TitrIC flex tailor workflows for drinking water, wastewater, industrial effluents and ultrapure water monitoring
• Cost and time efficiency: inline sample preparation, nested analysis and preconcentration maximize laboratory productivity

Future Trends and Possibilities

• Advanced hyphenation: coupling IC to high‐resolution MS and ICP‐MS for speciation of emerging contaminants
• Miniaturization and field deployable systems: portable potentiostats and optical sensing for in situ mapping
• Data integration and AI: digital twins and predictive analytics for real‐time water network monitoring and anomaly detection
• Green analytical chemistry: further reduction of reagent volumes and waste via microfluidic channels and solvent‐free sample prep

Conclusion

Metrohm’s integrated analytical platforms provide a comprehensive toolkit for multi‐analyte water quality assessment. By combining classical titrations, ion‐selective measurements, high‐performance IC and sensitive voltammetry—augmented by advanced automation—laboratories can meet diverse regulatory, research and industrial demands with high throughput, trace‐level detection and robust data management.

Reference

[1] Metrohm Application Bulletins and Monographs (e.g., AB-178, AB-046, AB-433, Conductometry, Practical Ion Chromatography, Practical Titration, Polarography/Voltammetry).
[2] ISO, EN and US EPA methods cited (e.g., ISO 10304-1, 17289, 19340; EN ISO 8467; EPA 300.1, 314.0, 326).
[3] ASTM standards (e.g., D1246, D4658, D1426, D3590).