Lovibond Maxi Direct, Instruction Manual, Page: 132 / 268

130 MaxiDirect_2c 03/2010
1.1 Methods
Nitrogen, total HR
with Vario Tube Test
5 – 150 mg/l N
Insert the adapter for 16 mm Ø vials.
1. Open two TN Hydroxide HR digestion vials and add
the contents of one Vario TN Persulfate Rgt. Powder
Pack
(Note 2, 3).
2. Add
0.5 ml deionised water
to the prepared vial (this
is the blank, Note 4, 5).
3. Add
0.5 ml of the water sample
to the other prepared vial
(this is the sample).
4. Close the vials with the caps and shake to mix the
contents (at least 30 seconds, Note 6).
5. Heat the vials for
30 minutes
in the preheated reactor
at a temperature of
100°C
(Note 7).
6. After 30 Minutes remove the vials from the reactor.
(CAUTION: The vials are hot!)
Allow the vials to cool to room temperature.
7. Open the cooled digestion vials and add the contents of one
Vario TN Reagent A Powder Pack to each vial (Note 2).
8. Close the vials with the caps and shake to mix the
contents (at least 15 seconds).
9. Press [ ] key.
Wait for a reaction period of 3 minutes.
After the reaction period is finished proceed as follows:
10. Open the digestion vials and add the contents of one
Vario TN Reagent B Powder Pack to each vial (Note 2).
11. Close the vials with the caps and shake to mix the
contents (at least 15 seconds, Note 8).
12. Press [ ] key.
Wait for a reaction period of 2 minutes .
After the reaction period is finished proceed as follows:
13. Open
two TN Acid LR/HR (Reagent C) vials
and
add
2 ml of the digested, treated blank
to one vial
(this is the blank).
14. Add
2 ml of the digested, treated water sample
to
the other TN Acid LR/HR vial (this is the sample).
15. Close the vials with the caps and swirl the vials gently
several times to mix the contents (10 x, Note 9).
(CAUTION: Vials warm up) .
Countdown
3:00
start:
Countdown
2:00
start:
1 2
3 4
Ø 16 mm
8 1 2