ez GGA, conveniently packaged in single-use ampules. No more diluting, no more pipetting, and no more guessing. Simply crack the top of the ampule open and drop the entire ampule into your BOD bottle. The pre-measured GGA contains the standard 198 mg/L of BOD from Glucose plus Glutamic Acid (GGA). The presence of the glass ampule in your BOD bottle serves as a quick visual indicator that you added the GGA to your sample. Product is equivalent to Standard Methods.