LaMotte MINI BOD5 TEST KIT M-B User Manual

Page 3

Fill two 60 mL BOD bottles (2-2053) about half full with dilution water.

With an appropriately sized pipet or graduated cylinder dispense the

precalculated amount of the sample into each of the two 60 mL BOD

bottles. Fill each bottle with dilution water and insert stopper. Exclude all air

bubbles.

Fill two more 60 mL BOD bottles (2-2053) with only dilution water. Insert

stoppers.

Incubate one bottle containing diluted sample (Step 2) and one bottle

containing only dilution water (Step 3) at 20°C for 5 days. Ensure that the

area above the stopper contains distilled water. Check daily or use bottle

covers (not supplied) to prevent evaporation.

Follow the instructions below to run a dissolved oxygen determination on

the remaining BOD bottle from Step 2. Record the initial dissolved oxygen

content as D

. Run another dissolved oxygen determination on the

remaining BOD bottle from Step 3. Record initial dissolved oxygen content

for control as C

DIS SOLVED OX Y GEN DE TER MI NA TION PRO CE DURE

Fix ing the Sam ple

Add 8 drops of *Manganous Sulfate Solution (4167WT) and 8 drops of

*Alkaline Potassium Iodide Azide (7166WT) to the sample. Cap and

mix by inverting several times. A precipitate will form. Allow the

precipitate to settle below the shoulder of the bottle before proceeding.

Use the 1g spoon (0697) to add one level measure of Sulfamic Acid

Powder (6286). 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. Following

this, contact between the water sample and the atmosphere will not

affect test result. Once the sample has been “fixed” in this manner, it is

not necessary to perform the actual test procedure immediately.

Test Pro ce dure

Fill the test tube (0608) to the 20 mL line with the “fixed” sample.

Cap. If the color of the “fixed” sample is already a very faint yellow,

skip Step D.

Fill the Direct Reading Titrator (0377) with the Sodium Thiosulfate

Solution, 0.025N (4169) in the manner described in the Titrator

manual. Insert the Titrator into the center hole of the test tube cap.

While gently shaking the tube, slowly press the plunger to titrate until

the yellow-brown color is reduced to a very faint yellow.

Remove the titrator and cap. Be careful not to disturb the Titrator

plunger, as the titration begun in Step D will be continued in Step F.

Use the pipet (0392) to add 8 drops of Starch Indicator Solution

(4170). The sample should turn blue.