LaMotte DISSOLVED OXYGEN TEST KIT - Manual (Page 3)

DIS SOLVED OX Y GEN TEST PRO CE DURE
COL LEC TION & TREAT MENT OF THE WA TER SAM PLE
Steps 1 through 4 below describe proper sampling technique in shallow
water. For sample collection at depths beyond arm’s reach, special water
sampling apparatus is required (e.g., the LaMotte Water Sampling
Chamber, Code 1060; Model JT-1 Water Samplers, Code 1077; Water
Sampling Outfit, Code 3103; or Code 3-0026 Water Sampling Bottle).
1.
To avoid contamination, thoroughly rinse the Water Sampling
Bottle (0688-DO) with sample water three times.
2. Tightly cap the bottle and submerge to the desired depth. Remove
cap and allow the bottle to fill.
3. Tap the sides of the submerged bottle to dislodge any air bubbles
clinging to the inside. Replace cap while the bottle is still
submerged.
4. Retrieve bottle and examine it carefully to make sure that no air
bubbles are trapped inside. Once a satisfactory sample has been
collected, proceed immediately with Steps 5 & 6 to “fix” the
sample.
NOTE:
Be careful not to introduce air into the sample while
adding the reagents in Steps 5 & 6. Simply drop the reagents into
sample. Cap carefully, and mix gently.
5. Add 8 drops of *Manganous Sulfate Solution (4167) and 8 drops of
*Alkaline Potassium Iodide Azide (7166). Cap and mix by
inverting several times. A precipitate will form. Allow the
precipitate to settle below the shoulder of the bottle before
proceeding.
6. Add 8 drops of *Sulfuric Acid, 1:1. Cap and gently shake until the
reagent and the precipitate have dissolved. A clear-yellow to
brown-orange color will develop, depending on the oxygen content
of the sample.
NOTE: Following the completion of Step 6, contact between the water
sample and the atmosphere will not affect the test result. Once the
sample has been “fixed” in this manner, it is not necessary to perform
the actual test procedure immediately. Thus, several samples can be
collected and “fixed” in the field, and then carried back to a testing
station or laboratory where the test procedure is to be performed.