Thermo Fisher Scientific Ion Selective Electrodes Copper - Manual (Page 8)

Instruction Manual Copper Electrode
8
convenient concentration unit. Table 1 indicates some of these
concentration units.
TABLE 1
: Concentration Unit Conversion Factors
ppm
Cu +2 moles/liter
6354.0 1.0X10
-1
635.0
1.0X10
-2
63.5
1.0X10 -3
6.4
1.0X10
-4
MEASUREMENT PROCEDURES
Direct Measurement
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. The temperature of both sample
solutions and standard solutions should be the same.
Direct Measurement of Cupric Ion (using a standard pH/mV meter)
1. By serial dilution of the 0.1M or 1000 ppm standards,
prepare 10 -2 , 10 -3 , and 10 -4 M or 100 and 10 ppm standards
for the cupric ion. To 100 ml of each standard, add 2
ml of ISA. Prepare standards with a composition
similar to the samples if the samples have an ionic
strength above 0.1M.
2. Place 100 ml of the 10
-4
M or 10 ppm standard in a 150 ml
beaker, place the beaker on the magnetic stirrer and
begin stirring at a constant rate.
3. Lower the electrode tip(s) into the solution. Make
sure that the meter is in the mV mode. When the
reading has stabilized, record the mV reading.
4. Place 100 ml of the 10 -3 M or 100 ppm standard in a 150
ml beaker, place the beaker on the magnetic stirrer and
begin stirring at a constant rate.
5. After rinsing the electrode(s) with distilled water and
blotting dry, immerse the electrode tip(s) in the
solution. When the reading has stabilized, record the
mV reading.