PASCO CI-6507A pH Sensor - Manual (Page 3)

012-06832A pH Sensor
3
CAUTION: The electrode should not be
used in percholate, silver, sulfide, or
hydrofluoric solutions, or in solutions
containing acids or bases that are more
than 1 Molar or at temperatures above
50 ºC. Use of the electrode at high
temperatures can shorten the electrode
life.
Taking a pH Measurement
1. Rinse the pH electrode in distilled water and
place it in the sample to be measured.
2. In the Experiment Setup window, set up a data
display (such as the Graph display) and begin
recording data.
Electrode Maintenance
Restoring the Electrode
Mechanically intact electrodes can often be restored
by one of the following procedures:
• General: Soak the electrode in 0.1 Molar
Hydrochloric Acid (HCl) for 15 minutes.
• Proteins: Soak the electrode in 1% Pepsin in 0.1
Molar Hydrochloric Acid (HCl).
• Inorganic Deposits: Rinse the electrode with 0.1
Molar Ethylene Dinitric Tetra-acidic Acid (EDTA)
Tetrasodium solution.
• Oil and Grease Film: Wash the electrode carefully
in a mild detergent or solvent known to be effective
for the particular film.
If the electrode is not working well, try soaking the
electrode alternately in 12 Molar NaOH (sodium
hydroxide) and 1 Molar HCl (hydrogen chloride), as
recommended in recent article from the Institute for
Chemical Education (ICE). Leave it in each solution
for one minute. Rinse completely between soakings,
and end with HCl. Apparently, the NaOH etches the
glass and the HCl reestablishes hydrogen ions on the
surface.
➤ Note: After any of these procedures, soak the
electrode in a pH 7 buffer solution for 30
minutes. If these steps fail to improve the
response of the electrode, it should be replaced.
Contact PASCO scientific about replacement
of the pH electrode.
Electrode Storage
The pH Electrode should not be stored dry and should
be stored as follows:
• Short Term Storage (up to one week): store in a pH
4 buffer solution or tap water.
• Long Term Storage (over one week): store in a pH
4 buffer solution with 1 gram per 100 milliliter of
potassium chloride (KCl) added.
➤ Note: The electrode should be rinsed but never
stored in distilled water.
Replacement Part
The pH electrode can be purchased separately as part
number 699-085.
Specifications
(pH electrode)
• pH range = 0 to 14
• electrode type = gel-filled (nonrefillable), Ag/AgCl
• output: 0.413V to -0.413V, corresponding to a pH
range 0 to 14 (0 V at pH 7)
• potential difference change/pH unit = 0.059 V
Specifications (pH amplifier)
• output: 0 to 1.4 V DC (.7 V corresponds to a pH of
7)
• pH-to-voltage ratio: 1 pH = 0.1 V