Hach DR/700 Procedures Manual page 199

HYDRAZINE,
10.
Place the
prepared sample in
the cell holder. Cap.
Note: In bright sunlight
it may be necessary to
close the cell
compartment cover.
SAMPLING AND STORAGE
Samples collected in glass or plastic bottles should be filled completely
and capped tightly. Avoid excessive agitation or exposure to air.
Samples must be analyzed immediately after collection and cannot be
preserved for later analysis.
ACCURACY CHECK
Standard Solution Method
To assure the accuracy of the test, prepare the following solutions:
a) Prepare a 25 mg/L stock solution by dissolving 0.1016 g of hydrazine
sulfate in demineralized water then diluting to 1000 mL. Prepare stock
solution daily.
b) Prepare a 0.1 mg/L (1000 µg/L) hydrazine working solution by
diluting 0.4 mL of the 25 mg/L stock solution to 100 mL with
demineralized water. Prepare just before analysis.
c) Use the working solution in place of the sample in Step 5. The result
should be 100 µg/L hydrazine.
STATISTICAL EVALUATION
A single operator repetitively tested samples of two laboratory prepared
solutions, using one DR/700, matched sample cells and two
continued
11.
Immediately
after the 12-minute
period press:
READ
The display will
count down to 0.
Then the display will
show the results in
µg/L hydrazine.
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