Easy, fast and simultaneous pH and conductivity measurements

Summary: Integrated pH and Conductivity Measurement with Thermo Scientific Gallery ECM

Significance of the topic

Accurate, frequent measurement of pH and conductivity is essential across food and beverage production, industrial process control, enzyme kinetics studies and environmental water analysis. Routine electrochemical monitoring protects equipment from corrosion and scaling, maintains product quality and regulatory compliance, and informs process optimisation. Automated, parallel measurement of pH and conductivity reduces laboratory bottlenecks, decreases operator exposure to reagents and enables faster decision-making across production and QA/QC workflows.

Objectives and overview of the product

This material describes the Thermo Scientific Gallery and Gallery Plus discrete analyzers equipped with an integrated electrochemical measurement (ECM) module. The ECM upgrade provides automated, parallel pH and conductivity testing alongside the instruments’ existing photometric analyses. Goals are to combine multiple test modalities in one automated platform, increase throughput, lower hands-on time and deliver auditable, standards-traceable results suitable for regulatory use.

Used instrumentation

• Thermo Scientific Gallery discrete analyzer and Gallery Plus discrete analyzer as the base photometric platforms.
• Integrated ECM (electrochemical measurement) module that slots into Gallery/Gallery Plus to enable simultaneous pH and conductivity testing.
• ECM module design: two electrodes arranged in series to measure conductivity and pH in parallel; standard measurement temperature 37°C with option for temperature-corrected reporting.
• Ready-to-use NIST-traceable calibration and verification standards for pH and conductivity (kits supplied as 2 × 60 mL vials). Specific reagent/product codes cited for calibration standards include pH 2, 4, 7, 10, 12 and conductivity standards 0.08 mS/cm, 1.4 mS/cm, 13 mS/cm and 112 mS/cm.

Methodology and workflow

The ECM module performs simultaneous electrochemical testing in parallel with photometric assays on the same samples. Samples and reagents are loaded into the discrete analyzer; the ECM electrodes sample the cuvette or flow path and perform conductivity and pH determinations in under one minute per sample. Calibration and verification are automated using the supplied NIST-traceable standards; typical operation includes automated calibration, verification runs and consolidated reporting and LIMS export. Parallel workflows reduce reagent consumption and sample waste compared with sequential, manual methods.

Main results and discussion

• Measurement capabilities: pH range 2–12; conductivity range approximately 20 µS/cm to 112 mS/cm.
• Throughput: up to 67 electrochemical (ECM) measurements per hour (with simultaneous photometric capability reaching up to ~350 photometric tests per hour on the same platform).
• Precision and accuracy: multi-matrix precision studies reported low relative standard deviations (RSD). For pH, total RSD across sample types was typically in the sub-1% range (approx. 0.08%–0.79% total RSD depending on matrix). For conductivity, total RSD values were typically around 0.2%–1.8% depending on sample conductivity and matrix. These results indicate robust repeatability for common matrices such as wine, juice, drinking and natural waters, sparkling water and wastewater.
• Regulatory and standards compliance: ECM measurements comply with multiple regional and international methods including EPA (e.g., EPA 150.2, EPA 120.1), ASTM (e.g., D1293, D1125), ISO (e.g., ISO-10523, ISO-7888), AOAC methods and Standard Methods entries (e.g., SM-4500-H+ and SM-2510).

Benefits and practical applications

• Consolidation: single automated platform performs both electrochemical and photometric analyses, reducing instrument footprint and simplifying workflows.
• Time and cost savings: parallel measurement reduces per-sample analysis time and reagent consumption and increases laboratory throughput and capacity.
• Operational robustness: automated calibration with NIST-traceable standards supports audit-ready results and simplifies method validation for regulated environments.
• Improved data delivery: faster and more frequent measurements enable production teams to respond more quickly to process deviations, improving product quality, reducing spoilage and protecting equipment.
• Safety and ergonomics: automation reduces hands-on manipulation of reagents and hazardous liquids, lowering operator exposure and error risk.

Future trends and possibilities for use

Integration of electrochemical modules into automated discrete analyzers aligns with broader laboratory automation trends. Anticipated developments and opportunities include:

• Expanded multiplexing: further integration of additional electrochemical sensors (e.g., ion-selective electrodes) or enhanced photometric assays to broaden the analyte panel measured in a single workflow.
• Advanced data integration: tighter LIMS/cloud connectivity and real-time dashboards for inline process control and predictive analytics driven by higher-frequency measurement data.
• Miniaturisation and green chemistry: continued reduction in reagent volumes and waste, with improved electrode chemistries to extend maintenance intervals.
• Temperature and matrix compensation algorithms: more sophisticated temperature correction and matrix-specific calibration models to further improve measurement robustness across diverse sample types.

Conclusion

Upgrading Thermo Scientific Gallery and Gallery Plus discrete analyzers with the integrated ECM module delivers simultaneous, automated pH and conductivity testing alongside photometric assays. The combined system improves throughput, reduces hands-on time and reagent use, and produces auditable, standards-compliant results suitable for regulated laboratories. Measured performance demonstrates high precision and repeatability across common matrices, making the solution well suited for food and beverage QA/QC, environmental water monitoring, enzyme kinetics and industrial process control.

References

• Regulatory standards and method references cited for ECM measurements: EPA 150.2; EPA 120.1; ASTM D1293; ASTM D1125; ISO 10523; ISO 7888; AOAC 973.41; AOAC 973.40; Standard Methods SM-4500-H+; SM-2510.
• NIST-traceable ECM calibration standards (product kits reported as 2 × 60 mL): pH standards at pH 2, 4, 7, 10, 12; conductivity standards at 0.08 mS/cm, 1.4 mS/cm, 13 mS/cm and 112 mS/cm. Product codes were provided by the manufacturer for ordering and audit purposes.