4.4.3. pH temperature principle
Please note that the closer the temperature of the sample solution to the calibration solution, the more
accurate the readings.
4.4.4. Factory default setting
For factory default setting, please refer to parameter setting P1.4 (Item 7.3). All calibration data is deleted
and the meter restores to the theory value (zero electric potential of pH is 7.00, the slope is 100%). Some
functions restore to the original value (refer to appendix -1). When calibration or measurement fails, please
restore the meter to factory default setting and then perform re-calibration or measurement. Please note
once it is set as factory default, all the data deleted will be irretrievable.
4.5 pH Electrode Maintenance
4.5.1. Daily maintenance
The soaking solution contained in the supplied protective bottle is used to maintain activation in the glass
bulb and junction. Loosen the capsule, remove the electrode and rinse in pure water before taking a
measurement. Insert the electrode and tighten the capsule after measurements to prevent the solution from
leaking. If the soaking solution is turbid or moldy, replace the solution. (Preparation: 26g KCL dissolved in
100ml pure water).
The electrode should not be soaked in pure water, protein solution or acid fluoride solution for long periods
of time. In addition, do not soak the electrode in organic silicon lipids.
For best accuracy, always keep the meter clean and dry, especially the and electrode connectors. Clean
with medical cottons and alcohol if necessary.
4.5.2. Calibration buffer solution
For calibration accuracy, the pH of the standard buffer solution must be reliable. The buffer solution should
be refreshed often, especially after heavy use.
4.5.3. Protect glass bulb
The sensitive glass bulb at the front of the combination electrode should not come in contact with hard
surfaces. Scratches or cracks on the electrode will cause inaccurate readings. Before and after each
measurement, the electrode should be washed with pure water and dried. Do not clean the glass bulb with
a tissue for it will affect the stability of the electrode potential and increase the response time. The electrode
should be thoroughly cleaned if a sample sticks to the electrode. Use a solvent if the solution does not
appear clean after washing.
4.5.4. Renew glass bulb
Electrodes that have been used over a long period of time will become aged. Submerge the electrode in
0.1mol/L hydrochloric acid for 24 hours, then wash the electrode in pure water, then submerge it in soaking
solution for 24 hours.
The method to prepare 0.1mol/L hydrochloric acid: dilute 9mL hydrochloric acid in pure water to 1000mL.
For serious passivation, submerge the bulb in 4% HF (hydrofluoric acid) for 3-5 seconds, and wash it in
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