eutech-instruments carbon dioxide gas User Manual
Instruction Manual
Carbon Dioxide Electrode
7
10
-2
440.0
1,000.0
10
-3
44.0
100.0
10
-4
4.4
10.0
MEASUREMENT PROCEDURE
Direct Measurement
Direct measurement is a simple procedure for measuring a large number of samples. A single meter
reading is all that is required for each sample. The ionic strength of samples and standards should
be made the same by adjustment with ISA for all carbon dioxide solutions. The temperature of both
sample solutions and standard solutions should be the same.
Direct Measurement of Carbon Dioxide (using a pH/mV meter)
1.
By serial dilution, prepare three standard solutions from the 0.1M or 1,000 ppm stock
standard. The resultant concentrations should be 10
standard. The resultant concentrations should be 10
-2
M, 10
-3
M, and 10
-4
M or 1,000 ppm,
100 ppm, and 10 ppm.
2.
Place 100 ml of the 10
-4
M (10 ppm) standard into a 150 ml beaker on the magnetic stirrer,
add 10 ml of carbon dioxide buffer, and begin stirring at a constant rate. After assuring that
the meter is in the mV mode, lower the electrode tip into the solution. After the reading has
stabilized, record the mV reading.
the meter is in the mV mode, lower the electrode tip into the solution. After the reading has
stabilized, record the mV reading.
3.
Place 100 ml of the 10-3M (100 ppm) standard into a 150 ml beaker on the magnetic
stirrer, add 10 ml of carbon dioxide buffer, and begin stirring at a constant rate. After
rinsing the electrode with distilled water, blot dry, and immerse the tip in the solution.
After the reading has stabilized, record the mV value.
stirrer, add 10 ml of carbon dioxide buffer, and begin stirring at a constant rate. After
rinsing the electrode with distilled water, blot dry, and immerse the tip in the solution.
After the reading has stabilized, record the mV value.
4.
Place 100 ml of the 10
-2
M (1,000 ppm) standard into a 150 ml beaker on the magnetic
stirrer, add 10 ml of carbon dioxide buffer, and begin stirring at a constant rate. After
rinsing the electrode with distilled water, blot dry, and immerse the tip in the solution.
After the reading has stabilized record the mV value.
rinsing the electrode with distilled water, blot dry, and immerse the tip in the solution.
After the reading has stabilized record the mV value.
5.
Using the semi-logarithmic graph paper, plot the mV reading (linear axis) against the
concentration (log axis). A typical calibration curve appears in Figure 1.
concentration (log axis). A typical calibration curve appears in Figure 1.