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Instruction Manual 

 

Ammonium Electrode 

 

7

9. 

Measure out 100 ml of the sample into a 150 ml beaker, add 1 ml of low level ISA, and 
place the beaker on the magnetic stirrer. Begin stirring. Lower the electrode tip(s) into the 
solution. 

 
10.  After the reading has stabilized, record the mV reading and determine the concentration 

from the low level calibration curve. 

 
11.  Prepare a new low level calibration curve daily. Check the calibration curve every 1-2 

hours by repeating Steps 3-7 above. 

 
Follow the procedure given for normal ammonium determinations using an ion meter and the blank 
correction procedure. 
 
 
ELECTRODE CHARACTERISTICS 
 

 
Direct electrode measurements reproducible to 

±2% can be obtained if the electrode is calibrated 

every hour. Factors such as temperature fluctuations, drift, and noise limit reproducibility. 
Reproducibility is independent of concentration within the electrode's operating range. 

 
Table 3 lists some common cations that, if present in high enough levels, will cause electrode 
interference and measurement errors or electrode drift when using the ammonium ion electrodes. 
 
Electrode drift and slow response could indicate the presence of high interference from the ions 
listed. Soak the electrode(s) in distilled water for an hour, then for two hours in ammonium standard 
solution to restore proper response. 
 
    TABLE 3:   Concentration of Possible Interference Causing a 10% Error at Various    
 

 

Levels of NH

4

Cl; Background Ionic Strength is 0.12M NaCl. 

 
    

Interference 

 (moles/liter) 10-

2

M NH

4

+1

   

10-

3

M NH

4

+1

 10-

4

M NH

4

+1

 

  

Cs

+1

 3.0X10-

3

 3.0X10-

4

 3.0X10-

5

 

 
  

K

+1

 1.0X10-

2

 1.0X10-

3

 1.0X10-

4

 

 
  

Tl

+1

 6.0X10-

2

 6.0X10-

3

 6.0X10-

4

 

 
  

H

+1

 1.0X10-

1

 1.0X10-

2

 1.0X10-

3

 

 
  

Ag

+1

 1.0X10

1

 1.0 

1.0X10-

1

 

 
 +Tris

+1

 1.0X10

1

 1.0 

1.0X10-

1