ORBECO SP600, Instruction Manual, Page: 188 / 334

186 SP600 Spectrophotometer 01/2008
1.1 Methods
Nitrogen, total LR
with Tube Test
0.5 – 25 mg/l N
1.
Open two TN Hydroxide LR digestion vials
and add
1 Vario TN Persulfate Rgt. powder pack (Note 2, 3).
2. Add
2 ml deionized water to the prepared vial (this is
the blank, Note 4, 5).
3. Add 2 ml of 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
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 reaction period is finished proceed as follows:
10. Open the digestion vials and add 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 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
2 8 0