eutech-instruments ammonium epoxy Manuel D’Utilisation

Instruction Manual 

 

Ammonium Electrode 

 

3

indicated by a slope of 90-100%. See the 

 section if the slope is not within this 

range. 
 
 
MEASUREMENT 
 

  
The sensing membrane is normally subject to water uptake and might appear milky. This has no 
effect on performance. All samples and standards should be at the same temperature for precise 
measurement, preferably ambient temperature. 
 
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 styrofoam sheet or asbestos sheet, between the stirrer and beaker. 
 
Always rinse the electrode tip(s) with distilled water and blot dry with a fresh tissue between 
readings to prevent solution carryover. 
 
Check the electrode for air bubbles adhering to the membrane surface after immersion in solution. 
Agitate the electrode gently to remove the air bubbles. 
 
A slow or sluggish electrode response may indicate surface contamination of the ammonium 
electrode membrane. Soak the electrode tip in distilled water for about 5 minutes to clean the 
membrane. Rinse the membrane and soak in diluted standard solution for about 5 minutes to restore 
performance. 
 
When measuring samples with high ionic strength, prepare standards with compositions similar to 
that of the sample. 
 
Dilute concentrated samples (over 0.1M) before measurement. Recalibrate every few hours for 
routine measurement. 
 

 
Make sure that the samples and standards are at the same temperature. About a 2% error will be 
introduced for a 1oC difference in temperature. Temperature should normally be less than 40oC 
with intermittent measurements allowed to 50oC. 
All samples and standards must be aqueous. They must not contain organic solvents. 
 
Interference found in Table 3 should be absent. 

 
Ammonium concentrations are measured in units of parts per million as ammonium, parts per 
million as N, moles per liter, or any other convenient concentration unit.  Table 1 indicates some of 
the concentration units.