eutech-instruments calcium epoxy ユーザーズマニュアル

Instruction Manual 

 

Calcium Electrode 

 

5

(Check electrodes each day) 
 

1. 

Prepare standard calcium solutions whose concentrations vary by tenfold. Use either the 
0.1M Ca

+2

, 1,000 ppm Ca

+2

, or the 100 ppm Ca

+2

 (as calcium carbonate) standard stock 

solutions.  Use the serial dilution method for this preparation. 

 
2. 

To a 150 ml beaker, add 100 ml of the lower 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. Assure that the meter is in the concentration mode. 

 
3. 

Adjust the meter to the concentration of the standard and fix the value in the memory 
according to the meter manufacturer's instructions. 

 
4. 

Rinse the electrodes with distilled water and blot dry. 

 
5. 

To another 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%. See the 

sections if the slope is not within this range. 

 
 

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

o

C in temperature will result in a 4% measurement error. 

 
The sensing membrane is normally subject to water uptake and might appear milky. This has no 
effect on performance. 
 
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 with compositions similar to that of the 
sample. Always check to see that the membrane is free from air bubbles after immersion into 
standard or sample. 
 
A slow responding electrode may be caused by interferences to the electrode. To restore proper 
performance, soak the electrode in distilled water for about 5 minutes to clean the membrane, rinse, 
and soak in diluted standard solution for about 5 minutes.