109
•
For sample digestion use a block heater reactor with holes to accom-
modate digestion vials. Use of the optional HI 740217 safety shield
is strongly recommended.
Preheat the Hanna Reactor C 9800 to 150 °C (302°F). For correct
use of the reactor follow Reactor Instruction Manual.
Do not use an oven or microwave because leaking
samples can generate a corrosive and possibly
explosive atmosphere.
•
Remove the cap from a reagent vial for the COD-HR.
Note: The reagent is light sensitive, thus store the
unused vials in their container and in a refrigerator
if possible.
•
Use the supplied syringe to add exactly 0.2 mL of
sample to the vial, while keeping the vial at a 45-
degree angle. This is the sample.
•
Replace the cap tightly and mix by inverting the
vial a couple of times.
Warning: as the vial becomes very hot, be careful
in handling it.
•
Using the other clean syringe, add to another reagent vial exactly
0.2 mL of deionized water, while keeping the vial at a 45-degree
angle. Replace the cap tightly and invert several times. This is the
blank.
Warning: as the vial becomes very hot, be careful in handling it.
Note: for an accurate measurement:
1) run a blank with each set of samples and use the same box of
reagents for blank and samples.
2) use two graduated pipettes to deliver exactly 0.2 mL of deionized
water and 0.2 mL of sample to the vials.
•
Insert the vials into the reactor and
heat them for 2 hours at 150°C.
•
At the end of the digestion period the Hanna Reactor will automatically
switch off. Wait for twenty minutes to allow the vials to cool to about
120°C.
•
Invert each vial several times while still warm,
then place them in the HI 740216 rack.
Warning: as the vials are still hot, be careful in
handling them.
COD HR
