Hach DR/850, Procedures Manual, Page: 319 / 460

319
17.
Place the vials in
the DRB 200 Reactor
that is preheated to 150
°C. Digest for 1 hour.
Note: Boiling sample in the
vials during digestion
indicates the vial is not
properly sealed; test results
will be invalid.
Note: Samples can be
digested up to 4 hours to
oxidize more resistant
organics. The prepared
blank must be treated in the
same manner.
Note: See DRB 200 user
manual for selecting pre-
programmed temperature
applications.
18.
Remove the vials
and place them in a
cooling rack for two
minutes to air cool. Then
cool the vials to room
temperature in a cool
water bath or running
tap water. This usually
takes about three
minutes.
Note: Occasionally a vial
will develop a colorless
upper layer and a purple
lower layer. Invert the vial
several times to mix and
proceed. This will not affect
test results.
19.
Remove the vials
from the water and wipe
with a clean, dry
paper towel.
Invert the vials several
times to mix.
20.
Insert the
COD/TNT Adapter into
the cell holder by
rotating the adapter until
it drops into place. Then
push down to fully insert
it.
Note: For increased
performance, a diffuser
band covers the light path
holes on the adapter. Do
not remove the diffuser
band.
2:00 minutes
OXYGEN DEMAND, CHEMICAL,
continued