Hach DR/850, Руководство по процедурам, Страница: 86 / 460

86
Sampling and Storage
Analyze samples for monochloramine immediately after
collection. If sampling with the sample cell, rinse the sample cell
several times with the sample, then carefully fill to the
10-mL mark. If sampling from a tap, let the water flow for at least
5 minutes. Let the container overflow with the sample several
times, then cap the container so there is no headspace (air) above
the sample.
Accuracy Check
1. Prepare the following monochloramine standard fresh before
use.
2. Add the contents of one Buffer Powder Pillow, pH 8.3 to
about 50-mL of organic-free water in a clean 100-mL Class A
volumetric flask. Swirl to dissolve the powder.
3. Using a Class A volumetric pipet, transfer 2.00 mL of
Nitrogen, Ammonia Standard Solution, 100 mg/L as NH
3
–N
into the flask.
4. Dilute to volume with organic-free water, cap and mix
thoroughly. This is a 2.00 mg/L buffered ammonia standard.
5. Pipet 50.00 mL of the buffered ammonia standard into a
clean 100-mL beaker. Add a stir bar.
9.
Press:
READ
The cursor will move
to the right, then
the result in mg/L
monochloramine (as Cl
2
or chosen units) will be
displayed.
CHLORAMINE, MONO, Low Range, continued