eutech-instruments cadmium epoxy User Manual
Instruction Manual
Cadmium Electrode
9
Added
Concentration
Step
Pipet
Volume (ml) ppm M
1
A
0.1
0.01
1.0X10
-7
2
A
0.1
0.02
2.0X10
-7
3
A
0.2
0.04
4.0X10
-7
4
A
0.2
0.06
6.0X10
-7
5
A
0.4
0.10
9.9X10
-7
6
B
2.0
0.29
2.9X10
-6
7
B
2.0
0.48
4.8X10
-6
Pipet A = 1 ml graduated pipet
Pipet B = 2 ml pipet
Solutions: additions of 10 ppm or 1.0X10
-4
M standard to 100 ml of solution prepared in
Step 3 above.
7.
On a semi-logarithmic graph paper, plot the mV reading (linear axis) against the
concentration (log axis) as in Figure 1.
concentration (log axis) as in Figure 1.
8.
Rinse the electrodes with distilled water and blot dry.
9.
Measure out 100 ml of the sample into a 150 ml beaker and add 1ml of low level ISA.
Place the beaker on the magnetic stirrer and begin stirring at a constant rate. Lower the
electrode tips into the solution. After the reading has stabilized, record the mV reading and
determine the concentration from the low level calibration curve.
Place the beaker on the magnetic stirrer and begin stirring at a constant rate. Lower the
electrode tips into the solution. After the reading has stabilized, record the mV reading and
determine the concentration from the low level calibration curve.
10. Prepare a new low level calibration curve daily. Check the calibration curve every two
hours by repeating Steps 3 - 7 above.
Low Level Cadmium Determination (using an ion meter)
1.
Using 20 ml of standard ISA, dilute to 100 ml with distilled water. This low level ISA
(1.0M NaNO
(1.0M NaNO
3
) is added at the rate of 1ml low level ISA to each 100 ml of solution. The
background ionic strength will be 1.0X10
-2
M.
2.
Follow the steps given in
Direct Measurement of Cadmium (using an ion meter)
to
the end of Step 6.
3.
To a 150 ml beaker, add 100 ml of distilled water and 1 ml of low level ISA. Place the
beaker on the magnetic stirrer and begin stirring at a constant rate.
beaker on the magnetic stirrer and begin stirring at a constant rate.
4.
Lower the electrode tips into the solution. When the reading has stabilized, fix the blank
value in the meter according to the meter manufacturer's instructions.
value in the meter according to the meter manufacturer's instructions.
5.
Continue with Steps 7-9 in
Direct Measurement of Cadmium (using an ion meter),
remembering to use the low level ISA described in Step 1 above.
Titration
Titration is a very accurate determination of total cadmium ion concentration. This method makes
use of the electrode as an endpoint detector when EDTA is used as a titrant.
use of the electrode as an endpoint detector when EDTA is used as a titrant.