RES1 Salt Bridges, Luggin Capillaries & Gas Bubblers for Electrochemical Cells

Salt Bridges & Luggin Capillaries for Electrochemical Cells

• Product Name: Salt Bridge / Luggin Capillary Tube
• Color: Transparent
• Function: Used with reference electrodes to protect electrodes and reduce potential drop
• Size: Customizable
• Material: Glass

Description

When current flows through an electrochemical cell, an ohmic potential drop exists between the two electrodes.
This effect is more pronounced in high-resistivity solutions or under large currents.
To minimize this effect, the glass tube at the reference electrode end is drawn into a fine capillary
(Luggin capillary) and positioned close to the working electrode.
This ensures that almost no current passes through the reference electrode circuit,
allowing accurate potential measurement using a high-impedance voltmeter.

Function

The Luggin capillary eliminates ohmic overpotential.
In a three-electrode system (working, counter, and reference electrodes),
the counter electrode regulates current density at the working electrode,
while the reference electrode precisely measures the electrode potential using a compensation method.

Usage Instructions

The tip of the Luggin capillary should be placed as close as possible to the working electrode surface
to minimize ohmic potential drop, but not too close to avoid shielding effects and distorted current distribution.
A general rule: the distance should not be less than the outer diameter of the capillary tip.

Preparation, Use & Maintenance

1. Dissolve 3 g agar in 97 ml distilled water in a water bath. Add 30 g KCl, stir until dissolved, and fill into pre-bent glass tubes while hot. Allow to set before use.
2. Agar-KCl salt bridges should not be used in solutions containing Ag⁺, Hg²⁺, or ions reacting with Cl⁻, or in solutions with ions reacting with K⁺ (e.g., ClO₄⁻).
3. Do not use above 80 °C. Recommended working temperature ≤ 70 °C.
4. After use, rinse salt bridges with deionized water to avoid contamination. Store in saturated KCl solution and replenish water regularly to prevent drying or cracking.
5. Saturated calomel electrodes should be stored in saturated KCl solution to maintain electrolyte stability. Check internal solution saturation before reuse.
6. Storage containers for salt bridges and calomel electrodes must not contain other items. Droppers dedicated to KCl must not be reused elsewhere.