Hach DR/700 Procedures Manual page 626

OXYGEN DEMAND, CHEMICAL,
continued
10.
Invert each vial
several times while
still warm. Place the
vials into a rack.
Wait until the vials
have cooled to room
temperature.
Note: If a pure green
color appears in the
reacted sample, the
reagent capacity may
have been exceeded.
Measure the COD and if
necessary, repeat the
test with a diluted
sample or use a higher
range digestion vial.
61-70