User Manual

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Returning to factory default setting is to restore the meter to the theoretical value (zero potential pH is 7.00, slope is
100%), and set all the parameters to default settings (see appendix 1). When the meter’s calibration or measurement
is performing abnormally, users can use this function to let the meter return to factory default mode, and conduct
calibration and then test again. Please note that this function is irreversible once used.
Maintenance of the pH Electrode
4.5.1. Daily maintenance
The soaking solution contained in the supplied protective vial is used to maintain the sensitivity of the glass bulb and
junction. Loosen the cap, remove the electrode and rinse in distilled water before taking a measurement. Insert the
electrode and tighten the cap after measurements to prevent the reference solution from leaking. If the soaking
solution is turbid or moldy, replace it with 3M KCL solution. (SKU: AI1107). Soaking the probe in other brands’ storage
solution could potentially cause damage to the probe.
The electrode should NOT be soaked in pure or distilled water, protein solution or acid fluoride solution. In addition,
do not soak the electrode in organic lipids.
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. We recommend 10-15 times of use before replacing the pH buffers.
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 rinsed with distilled water. If a sample sticks to the electrode or it’s contaminated, the electrode
should be thoroughly cleaned using a soft brush and then rinsed with distilled water. After that, soak it in the 3M KCL
(SKU: AI1107) solution again for 6 hours.
4.5.4 Renew glass bulb
Electrodes that have been used over a long period will become aged. Soak the electrode in 0.1mol/L hydrochloric
acid for 24 hours, then wash the electrode in distilled water, then soak it in 3M KCL (SKU: AI1107) storage solution
for 24 hours.
The method to prepare 0.1mol/L hydrochloric acid: dilute 9mL hydrochloric acid in distilled water to 1000mL.
For serious passivation, dip the bulb in 4% HF (hydrofluoric acid) for 3-5 seconds, and wash it in
distilled water, then soak it in the 3M KCL storage solution (SKU: AI1107) for 24 hours to renew it.
4.5.5. Clean contaminated glass bulb and junction (please refer to Table-5)
Table-5 Clean contaminated glass bulb and junction
Contamination
Cleaning Solutions