eutech-instruments ammonia gas User Manual
Instruction Manual
Ammonia Gas-sensing Electrode
2
5.
Eutech Ionic Strength Adjuster (ISA) Solution, 10 M NaOH, Code No. EC-ISA-AA1-BT.
To prepare this solution from your own laboratory stock, half fill a 1,000 ml beaker with
distilled water, add 400 grams of reagent-grade NaOH (sodium hydroxide). Swirl the flask
gently under a hood to dissolve the solid. Allow to cool and fill to the mark with distilled
water. Stir the solution and store in a plastic bottle.
To prepare this solution from your own laboratory stock, half fill a 1,000 ml beaker with
distilled water, add 400 grams of reagent-grade NaOH (sodium hydroxide). Swirl the flask
gently under a hood to dissolve the solid. Allow to cool and fill to the mark with distilled
water. Stir the solution and store in a plastic bottle.
6.
Eutech Ionic Strength Adjuster (ISA) Solution, 5M NaOH/.05M Disodium EDTA/10%
Methanol with Color Indicator, Code No. EC-ISA-AA2-BT. To prepare this solution from
your own laboratory stock, half fill a 1,000 ml beaker with distilled water and add 200
grams of reagent-grade NaOH. Stir the solution to dissolve the pellets, add 18.61 grams of
disodium EDTA, and stir the solution again until all solids have dissolved. Allow solution
to cool. In a separate 150 ml beaker, add a tiny amount (10-20 mg) of thymolphthalein to
100 ml of methanol and stir to dissolve. Pour the methanol solution into the 1,000 ml
beaker and stir to blend. The solution should turn a dark blue. Fill to the 1,000 ml mark
with distilled water and stir to blend.
Methanol with Color Indicator, Code No. EC-ISA-AA2-BT. To prepare this solution from
your own laboratory stock, half fill a 1,000 ml beaker with distilled water and add 200
grams of reagent-grade NaOH. Stir the solution to dissolve the pellets, add 18.61 grams of
disodium EDTA, and stir the solution again until all solids have dissolved. Allow solution
to cool. In a separate 150 ml beaker, add a tiny amount (10-20 mg) of thymolphthalein to
100 ml of methanol and stir to dissolve. Pour the methanol solution into the 1,000 ml
beaker and stir to blend. The solution should turn a dark blue. Fill to the 1,000 ml mark
with distilled water and stir to blend.
GENERAL PREPARATION
Electrode Preparation
This electrode is shipped dry. Before using, unscrew the large cap (See Figure 5), and remove the
inner glass electrode from the outer body. Fill the outer body with 2 to 3 ml of internal filling
solution. Place the inner glass electrode into the outer body, and screw on the large cap until finger
tight. Place the assembled electrode in an electrode holder with a 20
o
angle from the vertical to
avoid trapping air bubbles at the bottom of the electrode.
Checking Membrane
A small hole of any size on the membrane or breakage of the membrane causes failure of the
electrode. It is recommended to check the membrane on every newly assembled electrode.
1.
Connect a newly assembled electrode to a pH/mV meter.
2.
Lower the electrode tip in distilled water.
3.
Record the reading after stirring the distilled water for about 15 minutes.
4.
Add proper ISA solution (see
Required Solutions
) to the distilled water. A drastic change
in the reading in a negative direction indicates damage of the membrane.
Changing Membrane (see Figure 4)
1.
Unscrew the top cap from the outer body and remove the inner glass body from the epoxy
outer body. Carefully place the glass body aside.
outer body. Carefully place the glass body aside.
2.
Unscrew the bottom cap from the outer body. Remove the old membrane from around the
threads and electrode tip opening.
threads and electrode tip opening.
3.
Using the tweezers provided, grab a new piece of white membrane material by the edge
and remove from the separator paper. Then, with the hand not holding the tweezers, hold
and remove from the separator paper. Then, with the hand not holding the tweezers, hold