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IX. IX. IX. IX. IX. Quick Check of Electrode Slope
Quick Check of Electrode Slope
Quick Check of Electrode Slope
Quick Check of Electrode Slope
Quick Check of Electrode Slope
Connect sensors to pH/mV/ISE meter
Place meter in mV mode.
Place 100 mL of deionized water into a beaker with
stir bar and 2 mL of HI 4000-00 ISA. Add stir bar and
place on magnetic stirrer.
Place electrodes into prepared sample.
Add 1 mL of the stock standard HI 4003-01 (or .01 M
or .001 M standard by dilution) to the beaker.
Record the mV value when reading has stabilized.
Add an additional 10 mL of standard HI 4003-01 (or
same dilute standard) to the solution. Record the mV
when reading has stabilized. This value should be
more positive than the previous noted.
Determine the difference between the two mV values.
An acceptable value for this slope is +27 ± 4 mV
near 25°C.
X. X. X. X. X. Corrective action
Corrective action
Corrective action
Corrective action
Corrective action
Verify protective cap has been removed (HI 4003).
Verify plastic film has been removed from inner stem
(HI 4103).
Verify electrodes are connected properly to meter and
meter is powered.
Verify standard has been properly stored. Remake
standards if appropriate.
If the sensor slope just misses the suggested slope
window, soaking the sensor in a dilute standard may
solve the problem. (<10
A scratched, pitted or oxidized sensing surface can be
polished with HI 4000-70 polishing strip. Cut off
approximately 1 inch of the micro-abrasive strip. Wear
protective gloves. Wet the frosted side with deionized
water and place against damaged membrane of the
electrode. Place your gloved thumb against the shiny
backing and slowly rotate back and forth while
applying gentle pressure. Continue polishing until
you are satisfied with the surface. If dark deposits
10
-3
M standard).
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