Is your pH probe giving unreliable readings or refusing to calibrate properly?
Before replacing it, try a simple recovery process that can restore performance and extend its working life. This step-by-step probe recharge method is designed for school science technicians to safely clean, recondition and recalibrate probes back to working order.
Recovery Method (Probe Recharge Process)
Step 1: Acid Soak (Remove deposits)
Soak probe for 30 minutes in 0.1M hydrochloric acid (HCl)
Step 2: Rinse
Rinse thoroughly with distilled water
Step 3: Alkali Soak (Neutralise and recondition)
Soak for 30 minutes in 0.1M sodium hydroxide (NaOH)
Step 4: Rinse
Rinse thoroughly with distilled water
Step 5: (Optional – if the pH probe has been used in enzyme reactions)
Soak for 30 minutes in 1% pepsin solution
Rinse thoroughly with distilled water
Step 6: Rehydrate
Soak overnight in pH 7 buffer solution or probe storage solution
Step 7: Final Rinse
Rinse again with distilled water
Step 8: Recalibrate
Attempt calibration as normal
Safety Reminder
- Handle HCl and NaOH with appropriate PPE (gloves, goggles appropriate eyewear)
- Follow your school’s CLEAPSS guidelines