H75.0.01.6C-02
User’s guide GPH 114
Page 5 of 8
Problems may also occur when taking measurements in low-ion media containing solvent. Some of the
problems occurring when taking measurements in such media can be counteracted by using a double-
chamber electrode
(Type GE 103)
with suitable bridging electrolyte (type depending on application).
4.3 Selection of electrodes
Special electrodes for various applications:
1.
Measurements in low ion media
(rain water, water in aquariums, de-mineralized water)
our type GE 104 (special faceted electrode for > 50
μS/cm) or GE 106 (> 100μS/cm).
2.
Sea water aquariums
Standard combined measuring and reference electrodes
(GE 100, GE 114).
3.
Swimming pools
Standard pH electrodes
(GE 100, GE 114).
4.
Soil examinations
Glass electrode with several diaphragms
(GE 101)
. Use prick lance first!
5.
Cheese, fruit, meat
Insertion electrode
(GE 101)
.
When conducting measurements in cheese, milk and other products
containing proteins, a special cleaning agent has o be used for cleaning of the electrode
(pepsin solution
- GRL 100)
.
6.
Photographic laboratories
Use double chamber electrode, with jumpering electrolyte (1 molar potassium nitrate solution); potassium
nitrate solution has to be replaced as and when required. Fill watering cap with potassium nitrate solution
for storage of electrode.
(GE 103)
Normal cleaning
: 0.1 molar HCI solution for at least 5 min. or protein cleaning agent.
Generally speaking, the service life of electrodes is 8 to 10 months; with proper care and maintenance their
service life may even be extended to over 2 years. The actual service life is, however, dependant on the
individual application If you can no longer set the pH X-value this could either be an indication that
a) the electrode is worn out and needs to be replaced, or that
b) the buffer solution is used up (prepare new solution). Even if treated very carefully during calibration (to
avoid carrying over of buffer solution residuals from one solution to another if electrode is not sufficiently
cleaned and dried) buffer solutions only keep for a certain period of time (approx. 1 month).
Buffer capsules can be kept for an unlimited period of time - we, therefore, recommend keeping a certain
number on stock.
PH12-buffer-capsules (white) have to be stored in an exsiccator or stored together with drying agent.
We also recommend keeping a certain amount of 3 mol/l KCl on stock for re-filling.
4.4 General maintenance an measuring instructions
This pH electrode has been subjected to a series of tests demanding maximum quality standards in all
stages of manufacture.
Attached electrode can be used for 0 to 14 pH respectively at temperatures
between 0 and 90°C and conductivity > 200
μS/cm.
1. Make sure to observe the following points to maintain optimum capacity and accuracy of electrode
as long as possible:
1.1. Remove storage bottle from pH-electrode and rinse shaft and pH-glass diaphragm with ordinary tap
water. Then dry shaft with soft tissue.
1.2. Important! Make sure to always keep pH-glass diaphragm in a slightly moist condition. If electrode is not
used, the pH glass diaphragm has to be immersed into a 3 mol/l KCl solution for storage.
Drying out of the pH-glass diaphragm will affect both its capacity and sensitivity. In order to wet it
throughout, put glass diaphragm in a 3 mol/l KCl solution for 24 hours.
1.3. Please avoid touching of the glass diaphragm as even the slightest damage to, or abrasion of its surface
may negatively affect the capacity of the electrode.
1.4. Make it a rule to always visually check pH-electrodes for any air bubbles that might be enclosed in the
pH-glass diaphragm and the external reference electrode cell. In case of air bubbles being apparent,
these can be removed by shaking the electrode (downwards as for a clinical mercury thermometer)
1.5. During measurements the lateral diaphragm should also come into contact with the material to be
measured. Minimum immersion depth for GE 114 is 20 mm, max. 50 mm
1.6. Electrode cable and plug should always be clean and dry as otherwise the electrical insulation may be
damaged, this resulting in incorrect measurements as well as other faults.
