eutech-instruments ammonium epoxy User Manual
Instruction Manual
Ammonium Electrode
5
A calibration curve is constructed on semi-logarithmic paper when using a
pH/mV meter in the direct measurement procedure. The measured electrode
potential in mV (linear axis) is plotted against the standard concentration (log
axis). In the linear region of the curve, only three standards are necessary to
determine a calibration curve. In the non-linear region, additional points must be
measured. The direct measurement procedures given are for the linear portion of
the curve. The non-linear portion of the curve requires the use of low level
procedures. Extrapolate the curve down to about 1x10-
5
M or 0.2 ppm.
6.
To a clean, dry 150 ml beaker, add 100 ml of sample and 2 ml of ISA. Place the beaker on
the magnetic stirrer and begin stirring. Place the electrode tip(s) in the solution. When the
reading has stabilized, record the millivolt reading. Determine the concentration directly
from the calibration curve.
the magnetic stirrer and begin stirring. Place the electrode tip(s) in the solution. When the
reading has stabilized, record the millivolt reading. Determine the concentration directly
from the calibration curve.
7.
The electrode(s) should be re-calibrated every 1-2 hours. Simply repeat Steps 2-5 above.
Direct Measurement of Ammonium (using an ion meter)
1.
By serial dilution of the 0.1M or 1,000 ppm ammonium standard, prepare two ammonium
standards whose concentration is near the expected sample concentration. Measure out
100 ml of each standard into individual 150 ml beakers and add 2 ml of ISA to each.
standards whose concentration is near the expected sample concentration. Measure out
100 ml of each standard into individual 150 ml beakers and add 2 ml of ISA to each.
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.
Assure that the meter is in the concentration mode.
3.
Lower the electrode tip(s) into the solution.
4.
Adjust the meter to the concentration of the ammonium standard and fix the value in the
memory according to the meter manufacturer's instructions after stabilization of the
reading.
memory according to the meter manufacturer's instructions after stabilization of the
reading.
5.
Rinse the electrode tip(s) with distilled water and blot dry.
6.
Place the more concentrated solution on the magnetic stirrer and begin stirring at a
constant rate.
constant rate.
7.
Lower the electrode tip(s) into the solution.
8.
Adjust the meter to the concentration of the ammonium standard and fix the value in the
memory according to the meter manufacturer's instructions after stabilization of the
reading.
memory according to the meter manufacturer's instructions after stabilization of the
reading.
9.
For low level measurements, place the rinsed, dried electrode(s) into a solution containing
100 ml of distilled water and 2 ml of ISA. After stabilization, fix the blank value in the
meter according to the meter manufacturer's instructions.
100 ml of distilled water and 2 ml of ISA. After stabilization, fix the blank value in the
meter according to the meter manufacturer's instructions.
10. Place 100 ml of the sample and 2 ml of ISA in a 150 ml beaker, place it on the magnetic
stirrer, and begin stirring.