Hach DR2400 - Page 522

Nitrogen, Total Kjeldahl
Nitrogen, Total Kjeldahl
Page 2 of 6
NitrogenTK_None_Other_NES_Eng_Ody.fm
5. If the aliquot is less
than 1 mL, proceed to
step 6.
If it is greater than 1 mL,
add drops of 8.0 N KOH
to each cylinder until the
first flash of blue color
appears. Stopper and
invert the cylinder after
each addition. Proceed to
the next step.
6. Add 1.0 N KOH to
each cylinder, one drop at
a time, mixing after each
addition. Continue until
the first permanent blue
color appears.
7. Fill both cylinders to
the 20-mL mark with
deionized water.
8. Add three drops of
Mineral Stabilizer to each
cylinder. Stopper and
invert several times
to mix.
9. Add three drops of
Polyvinyl Alcohol
Dispersing Agent to each
cylinder. Stopper and
invert several times
to mix.
10. Fill both cylinders to
the 25-mL mark with
deionized water. Stopper
and invert several times
to mix.
11. Pipet 1.00 mL of
Nesslers Reagent to each
cylinder. Stopper and
invert repeatedly.
The solution should not be
hazy. Any haze (turbidity)
will cause incorrect
results.
12. Touch the timer icon.
Touch
OK.
A two-minute reaction
period will begin.