Hach DR/850, Procedures Manual, Page: 315 / 460

315
Method 10067
OXYGEN DEMAND, CHEMICAL
(20 to 1,000 mg/L)
For water and wastewater
Manganese III Digestion Method
*
(with chloride removal)
* U.S. Patent 5,556,787
1.
Enter the stored
program number for
Manganese III COD.
Press:
PRGM
The display will show:
PRGM ?
Note: If samples cannot be
analyzed immediately, see
Sampling and Storage
following these steps.
Note: Preheat the COD
Reactor to 150 °C for use
later in the procedure.
2.
Press:
18 ENTER
The display will show
mg/L, COD and the
ZERO icon .
Note: For alternate forms
(O
2
), press the CONC key.
3.
Homogenize
100 mL of sample for
30 seconds in a blender.
Note: Blending promotes
even distribution of solids
and improves accuracy
and reproducibility.
Note: Continue mixing the
sample while pipetting if
suspended solids
are present.
Chloride Removal
Procedure
4.
Using a TenSette
Pipet or a pipet and
safety bulb, pipet 9.0 mL
of homogenized sample
into an empty glass
mixing cell. If the
sample COD exceeds
1000 mg/L, dilute the
sample as described in
Table 1 .
Note: If suspended solids
are present, continue mixing
the sample while pipetting.
Caution: Some of the chemicals and
apparatus used in this procedure may be
hazardous to the health and safety of the
user if inappropriately handled or
accidentally misused. Please read all
warnings and the safety section of this
manual. Wear appropriate eye protection
and appropriate clothing. If contact occurs,
flush the affected area with running water.
Follow all instructions carefully.