Winkler BOD Procedure

1. Add (1) ml. Manganous Sulfate to each 300 ml. BOD bottle to be tested with magnetic stirring bar in bottle. 
2. Add (1) ml. Alkaline Iodide Azide to each 300 ml. BOD bottle to be tested. 
3. Cap and shake each bottle. Let settle to half of bottle. Shake once again and let settle to half of bottle. 
4. Add (1) ml. of Sulfuric Acid to each BOD bottle. Gloves and safety glasses are required. 
5. Cap and shake each bottle. 
6. Pour off 100 ml. from each bottle using a graduated cylinder and save. 
7. Add 0.025N Sodium Thiosulfate to buret. Put BOD bottle tested on stirring plate and swirl with magnetic stirrer bar iin bottle. 
8. Record starting point on buret before titerating. 
9. Titrate while stirring to a pale straw color. 
    
10. Add 2 droppers of Starch Indicator solution. 
     
11. Continue dropwise to the disappearance of the blue color. This is the end point.
     
12. Subtract difference readings from buret. 
13. Proceed to the other bottles to be tested

Note: If blue color should return after reaching end point, disregard. If end point is overshot, see blue lab manual.

Thomas J. Sciarrino of Windsor Locks cooks up some handy Standard Operating Procedures for the Lab. Look for new procedures each month.