eutech-instruments carbon dioxide gas User Manual
Instruction Manual
Carbon Dioxide Electrode
8
A calibration curve is constructed on semi-logarithmic paper when using
the pH/mV meter in the millivolt mode. The measured electrode potential
in mV (linear axis) is plotted against the standard concentration (log axis).
In the linear region of the curve, only three standards are necessary to
determine a calibration curve. In the non-linear region, additional points
must be measured. The direct measurement procedures given are for the
linear portion of the curve.
the pH/mV meter in the millivolt mode. The measured electrode potential
in mV (linear axis) is plotted against the standard concentration (log axis).
In the linear region of the curve, only three standards are necessary to
determine a calibration curve. In the non-linear region, additional points
must be measured. The direct measurement procedures given are for the
linear portion of the curve.
6.
To a clean, dry, 150 ml beaker add 100 ml of sample and add 10 ml of carbon dioxide
buffer. Place the beaker on the magnetic stirrer and begin stirring. Rinse the electrode with
distilled water, blot dry, and lower the tip in the solution. When the reading has stabilized
record the mV value. Using the calibration curve, determine the sample concentration.
buffer. Place the beaker on the magnetic stirrer and begin stirring. Rinse the electrode with
distilled water, blot dry, and lower the tip in the solution. When the reading has stabilized
record the mV value. Using the calibration curve, determine the sample concentration.
7.
The calibration should be checked every 1-2 hours. Assuming no change in ambient
temperature, place the electrode tips in the mid-range standard. After the reading has
stabilized, compare it to the original reading recorded in Step 3 above. A reading differing
by more than 0.5 mV or a change in the ambient temperature will necessitate the repetition
of Steps 2-5 above. A new calibration curve should be prepared daily.
temperature, place the electrode tips in the mid-range standard. After the reading has
stabilized, compare it to the original reading recorded in Step 3 above. A reading differing
by more than 0.5 mV or a change in the ambient temperature will necessitate the repetition
of Steps 2-5 above. A new calibration curve should be prepared daily.
Direct Measurement of Carbon Dioxide (using an ion meter)
1.
By serial dilution of the 0.1M or the 1,000 ppm standards, prepare two standards whose
concentration is near the expected sample concentration. Add 10 ml of carbon dioxide
buffer to each 100 ml of standard. When calibrating, assume that the added buffer has no
effect on the standard concentration.
concentration is near the expected sample concentration. Add 10 ml of carbon dioxide
buffer to each 100 ml of standard. When calibrating, assume that the added buffer has no
effect on the standard concentration.
2.
Place the more dilute standard on the magnetic stirrer and begin stirring at a constant rate.
Assure that the meter is in the concentration mode. Lower the electrode tip into the
solution.
Assure that the meter is in the concentration mode. Lower the electrode tip into the
solution.
3.
Adjust the meter to the concentration of the CO
2
standard and fix the value in the memory
according to the meter manufacturer's instructions after stabilization of the reading.
4.
Rinse the electrode with distilled water and blot dry. Place the more concentrated standard
on the magnetic stirrer and begin stirring at a constant rate.
on the magnetic stirrer and begin stirring at a constant rate.
5.
Lower the electrode tip into the solution. Adjust the meter to the concentration of the
carbon dioxide standard and fix the value in the memory according to the meter
manufacturer's instructions after stabilization of the reading.
carbon dioxide standard and fix the value in the memory according to the meter
manufacturer's instructions after stabilization of the reading.
6.
After rinsing the electrode and blotting dry, place the electrode tip into 100 ml of the
sample and 10 ml of carbon dioxide buffer. After stabilization, read the concentration
directly from the meter display.
sample and 10 ml of carbon dioxide buffer. After stabilization, read the concentration
directly from the meter display.
7.
The calibration should be checked every 2 hours. Assuming no change in ambient
temperature, place the electrode tip in the first carbon dioxide standard. After the reading
has stabilized, compare it to the original reading in Step 4 above. A reading differing by
more than 0.5 mV or a change in ambient temperature will necessitate the repetition of
Step 2-8 above. The meter should be re-calibrated daily.
temperature, place the electrode tip in the first carbon dioxide standard. After the reading
has stabilized, compare it to the original reading in Step 4 above. A reading differing by
more than 0.5 mV or a change in ambient temperature will necessitate the repetition of
Step 2-8 above. The meter should be re-calibrated daily.