Hach DR/700 Procedures Manual page 480

DEHA,
continued
10.
Press:
ZERO
The display will
count down to 0.
Then the display will
show 0 µg/L and the
zero prompt will turn
off.
OTHER OXYGEN SCAVENGERS
To determine other oxygen scavengers, perform the test as directed
above; then multiply the DEHA result by the appropriate factor:
Erythorbic Acid (Iso-ascorbic acid)
Hydroquinone
Methylethylketoxime
11.
Immediately
place the prepared
sample in the cell
holder.
Note: Typical indoor
lighting permits the
DR/700 to operate with
the cell compartment
open. In bright
sunlight, it may be
necessary to close the
cell compartment cover.
Transfer 10 mL of the
blank and 10 mL of the
sample to a
10-mL sample cell and
proceed.
55-32
12.
Press:
READ
The display will
count down to 0.
Then the display will
show the results in
µg/L DEHA.
Note: Repeat the above
procedure, omitting Step
7, to determine the
ferrous iron
concentration in the
sample. Subtract this
result from those
obtained in Step 12 to
determine the actual
DEHA concentration.
Factor
3.5
2.5
4.1