Oxygen, Dissolved
© Hach Company, 2003. All rights reserved. Printed in the U.S.A. 3/04 1ed
Page 2 of 2 OxygenDis_AccuVac_Low_INC_Eng_Ody.fm
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Interferences
Excess amounts of thioglycolate, ascorbate, ascorbate + sulfite, ascorbate +
cupric sulfate, nitrite, sulfite, thiosulfate, and hydroquinone will not reduce the
oxidized form of the indicator and do not cause significant interference.
Sample Collection, Preservation, and Storage
The main 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 ampule. 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:
1. Fill a 50-mL beaker with sample and add approximately 50 mg sodium
hydrosulfite.
2. Immerse the tip of a Low Range Dissolved Oxygen AccuVac Ampul in the
sample into the tip. Aspirate the sample into the ampule.
3. Determine the dissolved oxygen concentration according to the preceding
procedure. The result should be 0 ±6 µg/L.
Summary of Method
The Low Range Dissolved Oxygen AccuVac Ampul contains reagent vacuum
sealed in a 14-mL ampule. When the AccuVac Ampul is broken open in a sample
containing dissolved oxygen, the yellow solution will turn blue. The blue color
development is proportional to the concentration of dissolved oxygen. Test
results are measured at 610 nm.
Required Reagents
Quantity Required
Description per test Unit Cat. No.
Low Range Dissolved Oxygen AccuVac
®
Ampuls .............................1 ...................... 25/pkg...............25010-25
Required Apparatus
Sample Cells, 10-mL, w/cap...................................................................1 ....................... 6/pkg.................24276-06
Required Standards
Sodium Hydrosulfite, technical-grade ............................................................................ 500 g.......................294-34
Interfering Substance Interference Levels and Treatments
Hydrazine 100,000 fold excess will begin to reduce the oxidized form of the indicator solution.
Sodium hydrosulfite Reduces the oxidized form of the indicator solution and will cause a significant interference.
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