Separate half-cell and reference electrodes for HORIBA meters set up as two-electrode systems. A combination electrode packages both halves into one body; a two-electrode system keeps them apart, which lets you replace only the part that has failed and lets you choose a reference junction suited to a difficult sample.

A pH measurement is a voltage between two half-cells: the glass electrode responds to hydrogen ion activity, and the reference electrode holds a fixed, known potential. Most drifting, unstable or slow pH readings originate in the reference — its junction clogs or its internal solution becomes contaminated — not in the glass. Being able to swap the reference alone is why laboratories running awkward samples still prefer two-electrode setups.

pH glass half-cell

• 1066A-10C (3014080432) — glass pH electrode. Requires a separate reference electrode; compatible references are the 2060A, 2660A and 2565A.

Reference electrodes

• 2060A-10T (3014080434) — single ceramic liquid junction. The standard choice for clean aqueous samples, with a low, stable flow rate.
• 2565A-10T (3014080436) — double liquid junction. The second chamber isolates the internal silver/silver chloride element from the sample, which prevents silver from precipitating in samples containing sulfides, proteins, heavy metals or tris buffers, and stops sample ions from poisoning the reference.

When to choose a double junction

Use the 2565A-10T if your samples contain sulfide, chloride-sensitive chemistry, protein, or anything that reacts with silver. A single-junction reference in those samples will clog at the junction, drift, and need frequent replacement. The double junction costs more initially but lasts far longer in that service.

Applications

• Laboratory pH measurement and potentiometric titration
• Ion-selective electrode measurements needing a dedicated reference
• Samples containing sulfides, proteins or heavy metals
• Wastewater, plating bath and process chemistry analysis
• Research setups where glass and reference are replaced on separate schedules

Documentation

• HORIBA water quality document library — electrode brochures and manuals

Related items

Reference electrode filling solutions, pH buffers, storage caps and electrode stands are in the Horiba Parts & Accessories collection.

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