eutech-instruments carbon dioxide gas User Manual
Instruction Manual
Carbon Dioxide Electrode
4
water, add 294 grams of Na
3
C
6
H
5
O7.2H
2
O (sodium citrate dihydrate). Swirl the flask
gently to dissolve the solid. Fill the flask to the mark with distilled water. Stir the solution
and adjust the pH of the solution to 4.5 with concentrated HCl. This buffer is used to adjust
the pH of the solution to the operating range of the electrode. To each 100 ml of sample
and standard solution, add 10 ml of carbon dioxide buffer.
and adjust the pH of the solution to 4.5 with concentrated HCl. This buffer is used to adjust
the pH of the solution to the operating range of the electrode. To each 100 ml of sample
and standard solution, add 10 ml of carbon dioxide buffer.
GENERAL PREPARATION
Electrode Preparation
This electrode is shipped dry. Before using, unscrew the large cap (See Figure 5), and remove the
inner glass electrode from the outer body. Fill the outer body with 2 to 3 ml of internal filling
solution. Place inner glass electrode into the outer body, and screw on the large cap until finger
tight. Place the assembled electrode in an electrode holder with a 20
o
angle from the vertical to
avoid trapping air bubbles at the bottom of the electrode.
Checking Membrane
A small hole of any size on the membrane or breakage of the membrane causes failure of the
electrode. It is recommended to check the membrane on every newly assembled electrode.
1.
Connect a newly assembled electrode to a pH/mV meter.
2.
Lower the electrode tip in distilled water.
3.
Record the reading after stirring the distilled water for about 15 minutes.
4.
Add proper buffer solution (see section
Required Solutions
) to the distilled water. A
drastic change in the reading in a positive direction indicates damage of the membrane.
Changing the Membrane
Unscrew the small cap from the outer body and remove the old membrane cartridge from the small
cap. Insert the new membrane cartridge into place, and re-assemble the electrode. (See Figure 4.)
Connecting the Electrode to the Meter
Connect the electrode to the meter according to the meter manufacturer's instructions. No external
reference electrode is required. To prevent air entrapment, mount the electrode at a 20
o
angle from
the vertical.
Electrode Slope Check (with pH/mV meter)
(Check electrodes each day)
1.
To a clean, dry, 150 ml beaker, add 90 ml of distilled water and 10 ml of carbon dioxide
buffer. Place the beaker on a magnetic stirrer and begin stirring at a constant rate. After
assuring that the meter is in the millivolt mode, lower the electrode tip into the solution.
Remove air bubbles by redipping probe.
buffer. Place the beaker on a magnetic stirrer and begin stirring at a constant rate. After
assuring that the meter is in the millivolt mode, lower the electrode tip into the solution.
Remove air bubbles by redipping probe.