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X. X.
X. X.
X.
Quick Check of Electrode SlopeQuick Check of Electrode Slope
Quick Check of Electrode SlopeQuick Check of Electrode Slope
Quick Check of Electrode Slope
• Connect BNC (connector) to pH/mV/ISE meter.
• Place meter in mV mode.
• Place 100 mL of deionized water into a vessel with
stir bar. Add 10 mL of ISA Hanna HI 4005-00.
• Place sensor into prepared sample.
• Add 1 mL of 1000 ppm or 0.1 M Carbon dioxide
standard to beaker and stir sample. Wait approxi-
mately 5 minutes. Record the mV value when stable.
• Add an additional 10 mL of standard to the solution.
Record the mV when reading has stabilized (approxi-
mately 5 minutes). This value should be greater
than the previous noted (more positive).
• Determine the difference between the two mV values.
An acceptable value for this slope is 54±4 mV at
ambient temperatures between 20 and 25°C.
XI.XI.
XI.XI.
XI.
Corrective actionCorrective action
Corrective actionCorrective action
Corrective action
• Verify standard has been properly added.
• Verify ISA has been added in the correct ratio to the
standard (1 part ISA to 10 parts sample or standard).
• Verify that the upper cap has been screwed in all the
way.
• Verify electrode is connected properly to meter and the
meter is is powered .
• Verify membrane cap is tightened securely to probe
body.
• Examine the membrane for discoloration or perfora-
tions or for internal fill solution that might have
leaked through the PTFE membrane. Replace mem-
brane cap if damaged.
If drift is seen:
• Verify electrode and standards are at same tempera-
ture.
• Verify electrode has adaquate fill solution.
• Verify electrode was not left in air for prolonged pe-
riod.
