eutech-instruments cadmium epoxy Manuel D’Utilisation

Instruction Manual 

 

Cadmium Electrode

 

 

5

5. 

To a 150 ml beaker, add 100 ml of the higher value standard and 2 ml of ISA. Place the 
beaker on the magnetic stirrer and begin stirring at a constant rate. Lower the electrode tips 
into the solution. 

 
6. 

Adjust the meter to the concentration of the standard and fix the value in the memory. 

 
7. 

Read the electrode slope according to the meter manufacturer's instructions. Correct 
electrode operation is indicated by a slope of 90-100%. If the slope is not within this range, 
see the 

TROUBLESHOOTING 

sections if the slope is not within this range. 

 
 

MEASUREMENT 
 

 
All samples and standards should be at the same temperature for precise measurement. A difference 
of 1

o

C in temperature will result in about a 2% measurement error. 

 
Constant, but not violent, stirring is necessary for accurate measurement. Magnetic stirrers can 
generate sufficient heat to change the solution temperature. To counteract this effect, place a piece 
of insulating material, such as a styrofoam sheet, between the stirrer and beaker. 
 
Always rinse the electrode tips with distilled water and blot dry. Use a clean, dry tissue to prevent 
cross-contamination. 
 
For samples with high ionic strength, prepare standards whose composition is similar to the sample. 
 
Use fresh standards for calibration. 
 
Use 2 ml of ISA for each 100 ml of sample or standard. 
 
Always check to see that the membrane is free from air bubbles after immersion into the standard or 
sample. Dilute concentrated samples (>0.1M) before measurement. 
 

 
All samples must be aqueous and not contain organics which can dissolve the epoxy electrode body 
and/or the cement bonding the sensing crystal to the electrode body. Infrequent measurements in 
solutions containing methanol, benzene, or acetonitrile are permitted. Highly polar solvents slowly 
attack the electrode. Please check with Eutech Instruments Pte Ltd. before using these electrodes in 
other organic solvents. 
 
The temperature of the sample solutions and of the standard solutions should be the same and below 
80oC. About a 4% error in the slope will occur for each 1

o

C difference in temperature. Interferences 

should be absent. If they are present, use the procedure found in the 

Interference 

and

 Electrode 

 sections to remove them. 

 
Adjust sample pH with 1M HNO

3

 to below pH 7 to avoid precipitation of cadmium hydroxide, 

Cd(OH)

2

.