Chemetrics K-7512 Instruction Manual

Test Method

The Oxygen CHEMets®1test kit employs the indigo carmine
method

2,3

. In an acidic solution, oxygen oxidizes the yellow­green colored leuco form of indigo carmine to form a highly
colored blue dye. The resulting blue color is proportional to the
dissolved oxygen concentration in the sample. Test results are
expressed in ppm (mg/Liter) oxygen as O

2

.

1. CHEMets is a registered trademark of CHEMetrics, Inc. U.S. Patent No.

3,634,038

2. ASTM D 888 - 87, Dissolved Oxygen in Water, Test Method A

3. Gilbert, T. W., Behymer, T. D., Castaneda, H. B., "Determination of Dissolved

Oxygen in Natural and Wastewaters," American Laboratory

, pp. 119-134, March

1982

Safety Information

Read MSDS before performing this test. Wear safety glasses
and disposable gloves.

Important Note

The CHEMet ampoules contain a light sensitive reagent. They
will remain stable only if stored in the dark.

CHEMetrics, Inc., 4295 Catlett Road, Calverton, VA 20138-0214 U.S.A.

Phone: [phone]; Fax: [phone]; E-Mail: [e-mail]

www.chemetrics.com

Aug. 08, Rev 9

Oxygen CHEMets® Kit

K-7512: 1 - 12 ppm

Sampling

The most critical part of any dissolved oxygen test is sampling.
It is difficult to obtain an aliquot which accurately reflects the
oxygen content of a sample. Exposure to the high oxygen
content of "air" will cause a sample to approach saturation.
Biological activity may cause rapid oxygen depletion. Dipping
and pouring operations should be performed with as little
agitation as possible.

Test Procedure

1. Fill the sample cup to the 25 mL mark with
the sample to be tested (fig 1).

2. Place the ampoule in the sample cup.
Snap the tip by pressing the ampoule
against the side of the cup. The ampoule
will fill, leaving a small bubble to facilitate
mixing (fig. 2).

3. Mix the contents of the ampoule by
inverting it several times, allowing the
bubble to travel from end to end. Dry the
ampoule and wait 2 minutes for color
development.

4. Hold the comparator in a nearly horizontal
position while standing directly beneath a
source of light. Place the ampoule
between the color standards moving it
from left to right along the comparator until
the best color match is found (fig 3). If the
color of the ampoule is between two color
standards, a concentration estimate can
be made.

Figure 1

Î

Î

Figure 3

Figure 2