Xylem ISE Electrodes Nh 1100 - Manual

Instruction manual for
SCHOTT ® Instruments
Ammonia electrode
NH 1100
Preparation and general
Remove the electrode protection cap and rinse the
electrode with deionised water. Fill approx. 1 ml electrolyte
solution (L640 8) into the membrane module. Don’t touch
the membrane! Remove air bubbles in the electrolyte space
by patting. Screw the membrane module onto the electrode
and rinse the electrode with deionised water. Store the
electrode for approx. 1 h in 0.1 M NaOH before calibration
and measurement. The electrode is now ready for usage,
but has to be calibrated at first.
In Preparation for calibration
Please also follow the instruction manual of the measuring
device during calibration and measurement. The NH
electrode is connected like a pH electrode to the pH meter.
Switch the pH meter to the mV range.
For the calibration procedure the following solutions are
required:
Buffer solution :
1 M NaOH; 0.1 M EDTA
Dissolve 40 g NaOH and 29 g EDTA in 800 ml deionised
water. After cooling down to room temperature, fill up to
1000 ml.
Main calibration solution:
1000 mg N/l NH
4
+
Dissolve 3.819 g NH 4 Cl in deionised water and fill up to
1000 ml.
Dilution series:
Prepare different calibration solutions (for example 100, 10,
1 mg N/l) by diluting the main calibration solution.
Calibration
Take 100 ml of the calibration solution with the lowest
NH
4
Cl concentration and add 10 ml buffer solution. Stir the
solution. Immerse the electrode and record the potential
after the reading is constant (approx. 2 – 8 min). Repeat the
procedure with the other calibration solutions in sequence
of increasing concentration. The calibration curve is plotted
half-logarithmic: the electrode potential linear against the
logarithm of the concentration.
Diagram example: calibration curve
0,1
1
10
100
1000
-225 -200 -175 -150 -125 -100 -75 -50 -25 0 25 50
Measurement
Handle the samples like the calibration solutions. Take
100 ml of the sample and add 10 ml buffer solution. Stir the
solution. Immerse the electrode and record the potential
after the reading is constant (approx. 2 – 8 min). Read the
concentration from the calibration curve.
Storage and maintenance
Electrodes should be stored at a temperature between
0 and 40 °C. For a short time (1 – 2 days): in 0.1 M NaOH,
with exchange membrane module on. For more than 2
days: remove the membrane module and rinse the
electrode. Screw on the protection cap.
Quality
Every electrode must meet the strict quality requirements of
final testing. The working life strongly depends on the
usage conditions. Extreme conditions include for example
high or frequently changing temperatures and heavily
polluted solutions.
Technical Data
Measuring range: 0.1 – 1000 mg/l NH 4 -N
Temperature range : 0 – 50°C
Shaft material: POM Copolymer
Membrane : gas-permeable
Immersion depth: 10 – 50 mm
Order data
NH 995 : 3 membrane modules, 3 caps
NH 998 : 50 ml electrolyte, 3 membrane modules
L 6408 : 50 ml electrolyte
Subject to technical amendment.
GA_NH1100_us_8140287_090701
Electrode plug head
pH glass electrode
U/mV
mg/l NH
4
+ -N
Plastic shaft
Membrane module
and protection cap
for delivery
Ag/AgCl reference
electrode
Gas permeable
membrane
®
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