eutech-instruments chloride epoxy User Manual
Instruction Manual
Chloride Electrode
10
Low Level Chloride Determination (using a pH/mV meter)
Use the following low level chloride measurement procedure in the non-linear portion of the
calibration curve. (See Figure 1). This procedure is recommended for solutions containing less than
1.0X10
-4
M.
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 1 ml low level ISA to each 100 ml of sample. The
background ionic strength will be 1.0X10
-2
M.
2.
Dilute 10 ml of 0.1M standard to 100 ml to prepare a 1.0X10
-2
M standard solution for
measurements in moles per liter. Use the 1,000 ppm standard for measurements in ppm.
Standards should be prepared fresh daily.
Standards should be prepared fresh daily.
3.
Add 1 ml of the low level ISA to a 100 ml volumetric flask and fill to the mark with
distilled water. Pour this solution into a 150 ml beaker and place the beaker on the
magnetic stirrer. Begin stirring at a constant rate.
distilled water. Pour this solution into a 150 ml beaker and place the beaker on the
magnetic stirrer. Begin stirring at a constant rate.
4.
Place the electrode tips in the solution. Assure that the meter is in the mV mode.
5.
Add increments of the 1.0X10
-2
M or 1,000 ppm standard as given in Table 2 below.
6.
After the reading has stabilized, record the mV reading after each addition.
TABLE
2: Step-wise Calibration for Low Level Chloride Measurements
Added
Concentration
Step
Pipet Volume (ml)
M
ppm
1
A
0.1
1.0X10
-5
1.0
2
A
0.1
2.0X10
-5
2.0
3
A
0.2
4.0X10
-5
4.0
4
A
0.2
6.0X10
-5
6.0
5
A
0.4
9.9X10
-5
9.9
6
B
2.0
2.9X10
-4
29.0
7
B
2.0
4.8X10
-4
48.0
Pipet A = 1 ml graduated pipet
Pipet B = 2 ml pipet
Solutions: additions of 1,000 ppm or 1.0X10
-2
M standard to 100 ml
of ISA as prepared in Step 3 above.
7.
On a semi-logarithmic graph paper, plot the millivolt reading (linear axis) against the
concentration (log axis) as in Figure 1.
concentration (log axis) as in Figure 1.
8.
Rinse the electrodes in distilled water and blot dry.