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🔌 Electrochemistry · Method

potentiometry

Ion conc by potential
🎯 Difficulty ★☆☆ Easy Duration About 1–2 h 🎯 Use Determination of pH, ion activity and ion concentration with ion-selective electrodes
📖 Principle
ISE potential is proportional to the log of ion activity (Nernst equation)
Below are 5 steps. Open each to see how to do it and add products to your shared list.

📋 Workflow

Full workflow, products add-to-cart directly
1

Electrode & meter setup

15 min
Mount the ISE and reference electrode and connect to the ion meter
💡 Tip Keep internal filling solution wet
⚠️ Caution Do not let the membrane dry
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2

Two-point calibration

20 min
Calibrate the slope using two standards of known concentration
💡 Tip Standards should bracket expected sample concentration
⚠️ Caution Rinse the electrode before calibration
🧪 Materials for this step (click to shop by spec/brand)
3

Sample preparation

15 min
Pretreat the sample per protocol and adjust ionic strength
💡 Tip Add ionic-strength adjustment buffer
⚠️ Caution Avoid volatile loss
🧪 Materials for this step (click to shop by spec/brand)
4

Potential measurement

20 min
Immerse the electrodes, wait for stable potential and record the reading
💡 Tip Stirring helps stabilize
⚠️ Caution Record after reading stabilizes
🧪 Materials for this step (click to shop by spec/brand)
5

Concentration & report

15 min
Calculate ion concentration from the calibration or direct readout
💡 Tip Standard addition improves accuracy in complex samples
⚠️ Caution Convert to original sample concentration
🧪 Materials for this step (click to shop by spec/brand)

⚠️ 5 Common Beginner Mistakes

  • Dried membrane failing the electrode
  • Inaccurate calibration biasing readings
  • Inconsistent ionic strength affecting activity
  • Slow response giving unstable readings
  • Clogged reference junction

❓ FAQ

+Why activity not concentration?
Potential responds to activity; adjuster maintains consistency.
+Slow electrode response?
Check membrane fouling/reference clog; clean and maintain.
+How often calibrate?
Two-point calibrate before each use.

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Data authenticity: Product categories from JW Supply Chain standard taxonomy; method→step→product connected. Last updated: 2026-08-23 · v3.0