There are two methods for analyzing the standard:

The first method is called the Graphical Method:

• Add 1, 2, 3, and 4 mL of the standard to separate BOD bottles.

• The bottles are then filled with seeded dilution water and incubated at 20 °C for 5 days.

• The amount of dissolved oxygen remaining after 5 days is plotted against the volume of the standard used and a line of best fit (first order) is drawn through the points.

• The slope of the line is determined, and this value is multiplied by the volume of the BOD bottle to determine BOD value of the standard.

• The calculated value is then divided by 2 (since the GGA value of the standard is double that of Standard Methods) and the end result should be 198 +/- 30.5 mg/L.

This procedure is also described in the attached pdf file.

An alternate method (based on Standard Methods) is described below:

• Add 3 mL of the standard to a BOD bottle (since the GGA value of the standard is double that of Standard Methods, 3 mL, instead of 6 mL of standard is used).

• Fill the bottle with seeded dilution water and incubate at 20 °C for 5 days.

• Perform the same calculations on the standard, as on samples to determine the BOD value of the standard.

• The BOD should be 198 +/- 30.5 mg/L.

• It is recommended this analysis be run in triplicate.