Thermo Fisher Scientific Ion Selective Electrodes Copper - Manual (Page 11)

Instruction Manual Copper Electrode
11
solution and wait for the reading to stabilize. Read
the concentration directly from the meter display.
11. The calibration should be checked every two hours.
Assuming no change in ambient temperature, immerse the
electrode tip(s) in the more dilute standard. After
the reading has stabilized, compare it to the original
reading recorded in step 4 above. If the reading
differs by more than
∀0.5 units, or the temperature
has changed from ambient, recalibrate the electrode.
Low Level Cupric Determination (using a standard pH/mV meter)
This procedure is recommended for solutions with cupric
concentrations of less than 10
-5 M (0.6 ppm). If the solution is
high in ionic strength, but low in cupric ion, use the same
procedure, but prepare a calibration solution with a composition
similar to the sample.
1. Using 20 ml of standard ISA, dilute to 100 ml with
distilled water. This low level ISA (1.0M NaNO
3
) is
added at the rate of 1 ml low level ISA to each 100 ml
of solution. The background ionic strength will be
1.0X10
-2
M.
2. Dilute 1 ml of 0.1M standard to 100 ml to prepare a
1.0X10
-3
M solution. Dilute 1 ml of this solution to
prepare a 10
-5
M standard for measurements in moles per
liter. Prepare a 1 ppm standard solution by diluting 1
ml of the 1000 ppm standard to 1 liter of solution for
measurements in ppm. Standards should be prepared
fresh daily.
3. Add 100 ml of distilled water and 1 ml of low level ISA
to a 150 ml beaker. Place the beaker on the magnetic
stirrer and begin stirring at a constant rate.
4. Place the electrode tip(s) in the solution. Assure
that the meter is in the mV mode.
5. Add increments of the 1.0X10
-5
M or 1 ppm standard as
given in Table 2 below.
6. After the reading has stabilized, record the mV
reading.
TABLE 2
: Stepwise Calibration for Low Level Cupric Measurements
Added Concentration
Step Pipette Volume (ml) ppm M