How to Work with the pH Electrode pHydrunio

For the transport the internal buffer of pHydrunio is removed. Open the red transport plug and use the provided syringe and cannula to insert about 5 ml of the provided inner buffer solution pH 7 into the pHydrunio.
Replace the red transport plug in the electrode head with the enclosed red pressure relief valve, which is also a screw cap.

pHydrunio only works with the delivered buffer!

Manual (pdf)

First, unscrew the red cap on the electrode head. Unscrew the two black caps on the electrode head’s side as well. Remove the hydrogen cells underneath. In the recess you see small O-rings. Please grease them both with silicone grease, for example.
Take the new hydrogen cells and remove the protective foil. Two openings become visible. If any adhesive residue remains, remove it by rubbing it with a cloth.
Place the hydrogen cells in the recesses with the openings facing down.
Screw the black caps back in. Screw the red pressure relief valve back into the electrode head.
Important: Mark month and year on the label. Attach the sticker to the electrode head. Place pHydrunio in distilled water for 24 hours.

Replacement of hydrogen cells (pdf)

Manual (pdf)

First of all, the pH electrode is placed in calibration buffer pH 7. This determines the deviation from the zero point. Depending on the condition of the electrode, this may take several minutes. Note the measured voltage and the temperature of the buffer as soon as the voltage has become constant. Then, rinse the electrode and the temperature sensor with water before you place both in calibration buffer pH 4 or
pH 10. Here too, note the measured voltage and the temperature of the buffer as soon as the voltage has become constant. Waiting times of several minutes are possible.

Calibration curve for pHydrunio (jpg)

After the measurements, rinse the hydrogen pH electrode thoroughly with water. Please place the pH electrode in a vessel with distilled water.
Under no circumstances should it be stored with the transport cap. The hydrogen would slowly squeeze the small volume of liquid out of the cap.
The hydrogen pH electrode should not be stored dry in air as long as the hydrogen cells are generating hydrogen. Otherwise, a mixed potential forms, which can lead to incorrect results. Pay attention to the runtime of the hydrogen cells.

After the measurements, rinse the hydrogen pH electrode thoroughly with water. Please place the pH electrode in a vessel with distilled water.
Under no circumstances should it be stored with the transport cap. The hydrogen would slowly squeeze the small volume of liquid out of the cap.
The hydrogen pH electrode should not be stored dry in air as long as the hydrogen cells are generating hydrogen. Otherwise, a mixed potential forms, which can lead to incorrect results. Pay attention to the runtime of the hydrogen cells.

You can check both electrodes in the hydrogen pH electrode separated from each other against a so-called master electrode, e.g. a calomel electrode. The master electrode should always be placed in an appropriate potassium chloride solution and not be used for any other purpose.
Pay attention to the fill level in the calomel electrode itself. It must always be above the fill level in the measuring vessel. Open the filling plug of your calomel electrode to prevent the measuring fluid from entering the calomel electrode.

To check the hydrogen pH electrode pHydrunio, place pHydrunio and the master electrode in buffer pH 0. Connect the calomel electrode to the positive pole. To contact the pH electrode, you need an appropriate adapter BNC to 4 mm laboratory socket.
Now, connect the red socket of the adapter with the negative pole (COM-port) of your voltmeter. You are now checking the outer measuring electrode of the hydrogen pH electrode. After an adjustment phase, which can last several minutes, you read off the potential.
Afterwards, connect the black socket of the adapter with the negative pole (COM-port) of your voltmeter. You are checking the inner reference electrode of your pH electrode. After an adjustment phase, which can last several minutes, you read off the potential.
It is assumed that the pH-values stay constant in these temperature ranges. Diffusion voltages are not considered.

Potential table for pHydrunio in calibration buffer pH 0 (pdf)

The internal buffer (reference electrolyte) can be replaced. To do so, the sealing cap at the electrode’s head must be unscrewed. You can remove the internal buffer with the provided syringe and cannula. Rinse the electrode with distilled or deionized water. Fill in the new internal buffer directly from the vial. Screw down the pHydrunio carefully. Place pHydrunio in distilled water for 24 hours.

pHydrunio only works with the delivered buffer!

Manual (pdf)

First, unscrew the red cap on the electrode head. Unscrew the two black caps on the electrode head’s side as well. Remove the hydrogen cells underneath. In the recess you see small O-rings. Please grease them both with silicone grease, for example.
Take the new hydrogen cells and remove the protective foil. Two openings become visible. If any adhesive residue remains, remove it by rubbing it with a cloth.
Place the hydrogen cells in the recesses with the openings facing down.
Screw the black caps back in. Screw the red pressure relief valve back into the electrode head.
Important: Mark month and year on the label. Attach the sticker to the electrode head. Place pHydrunio in distilled water for 24 hours.

Replacement of hydrogen cells (pdf)

Manual (pdf)

1. Buffer solution
   Please measure in fresh buffer solution. If buffer solutions are exposed to air for a longer period of time, the pH value may shift.
   This occurs mainly with alkaline buffer solutions.
2. Slow ion exchange, e.g. when changing from concentrated solutions to weakly concentrated solutions
   Please take the adjustment time into account, sometimes the balancing of concentrations takes longer than expected. If necessary, check the potential in another electrolyte, e.g. in calibration buffers.
3. Internal buffer contaminated
   It can happen that measuring solution enters and contaminates the internal buffer.
   In that case, the internal buffer has to be replaced.
4. Poor contacting
   Check the measuring cables for optical damages such as corrosion, cracks, and sessile plugs. Replace the cables. Check both electrodes using an external reference electrode, e.g. a HydroFlex, calomel or silver silver chloride electrode.
5. Air/oxygen reaches the hydrogen electrode
   Avoid that gases such as air or oxygen reach the platinum hydrogen electrode’s shaft. If this happens the hydrogen is displaced or reacts off. No hydrogen potential can be set.
6. No or insufficient hydrogen production
   Has the runtime of the hydrogen cells been exceeded?
   If yes, please replace the hydrogen cells.

1. Hydrogen bubbles from the hydrogen electrode itself
   Bubbles are continuously leaking out of the platinum hydrogen electrode. Some bubbles are small, others are bigger. Usually, they do not disturb your measurements.
   Is a big bubble forming at the bottom of the hydrogen electrode which sticks to the vessel wall?
   If possible, place the electrode further away from the vessel wall or hang the hydrogen electrode transversely into the measuring vessel.
2. Induced gases
   Change the position of your gas inlet.
   Induced gas bubbles which are piped by close to the hydrogen electrode can disturb the measurements and lead to fluctuating potentials.