eutech-instruments ammonium epoxy User Manual

Ammonium Electrode 

 

Instruction Manual 

 

4

 TABLE 

1:  Concentration Unit Conversion Factors 

 
         ppm NH

4

+

    

ppm N                moles/liter NH

4

+

 

           1.80 

  1.40 

1x10

-4

 

          18.00 

 14.00 

1x10

-3

 

         180.00 

140.00 

1x10

-2

 

 
 
Measurement Procedure 
 

 
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 for all ammonium samples. The temperature of both sample solution and of 
standard solutions should be the same. 
 

 

1. Prepare 

10-

2

, 10-

3

, and 10-

4

M or 100, 10, and 1 ppm standards by serial dilution of the 

0.1M or 1,000 ppm standard.  Add 2 ml of ISA per 100 ml of standard. 

 
2. 

Place the most dilute solution (10-

4

M or 1 ppm) on the magnetic stirrer and begin stirring 

at a  constant rate. After assuring that the meter is in the mV mode, lower the electrode 
tip(s) into the solution.  When the reading has stabilized, record the mV reading. 

 
3. 

Place the midrange solution (10-

3

M or 10 ppm) on the magnetic stirrer and begin stirring. 

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. 

 
4. 

Place the most concentrated solution (10-

2

M or 100 ppm) on the magnetic stirrer and begin 

stirring. 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. 

 
5. 

Using the semi-logarithmic graph paper, plot the mV reading (linear axis) against the 
concentration (log axis). A typical calibration curve can be found in Figure 1.