Hach DR/850, Procedures Manual, Page: 277 / 460

277
Method 10021
NITROGEN, Total Inorganic, Test ‘N Tube
™ (0 to 25.0 mg/L N)
Titanium Trichloride Reduction Method
For water, wastewater, and seawater
Requires Centrifuge
1.
Enter the stored
program number for
Test ‘N Tube Total
Inorganic Nitrogen.
Press:
PRGM
The display will show:
PRGM ?
2.
Press:
68 ENTER
The display will show
mg/L, N and the
ZERO icon .
3.
Insert the COD/TNT
Adapter into the cell
holder by rotating the
adapter until it drops
into place. Then push
down to fully insert.
Note: For increased
performance, a diffuser
band covers the light path
holes on the adapter. Do
not remove the diffuser
band.
4.
Pipet 1 mL of Total
Inorganic Nitrogen
Pretreatment Base
Concentrate into each of
2 Total Inorganic
Nitrogen Pretreatment
Diluent Vials.
5.
Pipet 1 mL of sample
into 1 TIN Diluent Vial
(the sample). Pipet 1 mL
of deionized water into
the other vial (the
blank). Cap the vials and
shake for 30 seconds to
mix.
6.
Snap the necks off
two Total Inorganic
Nitrogen Reductant
ampules and pour the
contents of one into
the TIN Diluent Vial
containing sample.
Repeat for the second
vial, the blank.
Note: For safety, wear
gloves while breaking
the ampules.
Note: A black precipitate
will form immediately.
7.
Cap the vials. Shake
gently for 30 seconds to
mix the reagents. Allow
the vials to sit for at least
one minute.
Note: The precipitate
should remain black after
shaking. Excessive shaking
will cause a white
precipitate and low results.
8.
Centrifuge the vials
for 3 minutes or until the
solids settle to the
bottom of the vial.
Press:
TIMER ENTER
immediately after
starting the centrifuge.
Note: The precipitate will
settle without using a
centrifuge, but it may take
up to 30 minutes.