Hach DR/850, Procedures Manual, Page: 285 / 460

285
Method 10067
OXYGEN DEMAND, CHEMICAL
(20 to 1,000 mg/L)
For water and wastewater
Manganese III Digestion Method
*
(without 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.
4.
If chloride is not
present in significant
amounts
†
, pipet 0.50 mL
of homogenized sample
into a Mn III COD vial.
Cap and invert several
times to mix.
Note: If the sample COD
value is not between 20-
1000 mg/L dilute the
sample with deionized
water to obtain a range of
20-1000 mg/L COD.
Multiply the final result by
the dilution factor.
†
To determine if chloride
will interfere, run the
sample with and without
the chloride removal
procedure and compare
the results
.
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.