Справочник Пользователя для eutech-instruments ammonia gas

Instruction Manual 

 

Ammonia Gas-sensing Electrode

 

 

7

2. 

Place the more dilute solution on the magnetic stirrer and begin stirring at a constant rate.  
Assure that the meter is in the concentration mode. 

3. 

Lower the electrode tip into the solution. 

 
4. 

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

 
5. 

Rinse the electrode with distilled water and blot dry. 

 
6. 

Place the most concentrated solution on the magnetic stirrer and begin stirring at a constant 
rate. 

 
7. 

Lower the electrode tip into the solution. Adjust the meter to the concentration of the 
ammonia standard and fix the value in the memory according to the meter manufacturer's 
instructions after stabilization of the reading. 

 
8. 

For low level measurements, place the rinsed, dried electrodes into a solution containing 
100 ml of distilled water and 1 ml of ISA. After stabilization, fix the blank value in the 
meter according to the meter manufacturer's instructions. 

 
9. 

Place 100 ml of the sample and 1 ml of ISA in a 150 ml beaker. Place the beaker on the 
magnetic stirrer and begin stirring. 

 
10.  Lower the electrode tip in solution. When the reading has stabilized, read the concentration 

directly from the meter display. 

 
11.  The calibration should be checked every 2 hours. Assuming no change in ambient 

temperature, place the electrode tip in the first ammonia standard. After the reading has 
stabilized, compare it to the original reading in step 3 above. A reading differing by more 
than 0.5 units or a change in ambient temperature will necessitate the repetition of steps 2-
8 above.  The meter should be re-calibrated daily. 

 

 
As the concentration of ammonia decreases, the rate of ammonia diffusion through the membrane is 
slow, the rate of equilibrium between the ammonium in the internal filling solution and ammonia is 
slow, and thus the response time increases. If the internal filling solution is diluted with ammonia-
free distilled water (1:10), response at low levels can improve.  Measurements can be speeded up by 
first placing the electrode tip in an ammonia-free pH 4 buffer, then into the sample. Always keep 
standards and samples covered. Work with large solution volumes to minimize surface-area-to-
volume ratio, thereby avoiding ammonia absorption from air. Allow 5-10 minutes for a stable 
reading in the pH 4 buffer or a low-level solution. 
 
Use the following low level ammonia measurement procedure in the non-linear portion of the 
calibration curve. (See Figure 1.) This procedure is used for ammonia samples containing less than 
1.0x10-

5

M ammonia.