eutech-instruments calcium epoxy Manuel D’Utilisation

Calcium Electrode 

 

Instruction Manual 

 

6

Dilute concentrated samples (over 0.1M) before measurement. Recalibrate every few hours for 
routine measurement. 
 

 
All samples and standards must be aqueous and not contain organics which can dissolve in the 
membrane or extract out the liquid ion exchanger. 
 
The temperature of the standard solutions and of the sample solutions should be the same and below 
40

o

C. About a 2% error will be introduced for a 1

o

C difference in temperature.  

 
The pH range for the calcium ion electrode is 3-10. Neutralize samples outside this range with 
NaOH or HCl to bring them in range. 
 
Interferences should be absent. If they are present, use the procedures found in the 

 

section to remove them. 
 

 
Calcium concentrations are measured in units of ppm as calcium, ppm as CaCO3, moles per liter, or 
any other convenient concentration unit. Table 1 indicates some of the concentration units. 
 

     TABLE 1: Concentration Unit Conversion Factors 

 

            

ppm Ca

+2

    ppm CaCO

3

        moles/liter   

             

4.01             

10.0          

1.0X10

-4

         

             

10.00              24.9          

2.5X10

-4

         

             

40.10             100.1          

1.0X10

-3

     

            

400.80          1,000.9          

1.0X10

-2 

 
 
MEASUREMENT PROCEDURE 
 

 
Direct measurement is a simple procedure for measuring a large number of samples. A single meter 
reading is all that is required for each sample. The temperature of both sample solution and of 
standard solutions should be the same. 
 

 

1. 

By serial dilution prepare three standard solutions from the 0.1M, 1,000 ppm, or 100 ppm 
standard. The resultant concentrations should be 10

-2

, 10

-3

, and 10

-4

M or 100, 10 and 1 

ppm standards. Add 2 ml  of ISA to each 100 ml  of standard. 

 
2. 

Place the most dilute solution (1.0X10

-4

M or 1 ppm) in a 150 ml  beaker on the magnetic 

stirrer and begin stirring at a constant rate. After assuring that the meter is in the mV mode, 
lower the electrode tips into the solution. After the reading has stabilized, record the mV 
reading.