61-63
OXYGEN, DISSOLVED, LR, continued
10. Wipe the ampul
dry and immediately
place the prepared
sample in the cell
holder.
Note: In bright light it
may be necessary to
close the cell
compartment cover.
11. Press: READ
The display will
count down to 0.
Then the display will
show the results in
µg/L dissolved
oxygen.
SAMPLING AND STORAGE
The primary consideration in this procedure is to prevent contaminating
the sample with atmospheric oxygen. Sampling from a stream of water
that is hard plumbed to the sample source is ideal. Use a funnel to
maintain a continual flow of sample and yet collect enough sample to
immerse the ampul. It is important not to introduce air in place of the
sample. Rubber tubing, if used, will introduce unacceptable amounts of
oxygen into the sample unless the length of tubing is minimized and the
flow rate is maximized. Flush the sampling system with sample for at
least 5 minutes.
ACCURACY CHECK
The reagent blank for this test can be checked by following these steps:
a) Fill a 50-mL beaker with sample and add approximately 50 mg
sodium hydrosulfite.
b) Immerse the tip of a Low Range Dissolved Oxygen AccuVac Ampul
in the sample and break the tip. Aspirate the sample into the ampul.
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