high-temperature (>700
C) catalytic oxidation [1]. PON can be
determined using combustion at higher temperature (~1000
C)
with an oxidation catalyst followed by reduction to N 2
(or determined as the difference between TN in unfiltered and
filtered samples) [1]. Dissolved organic nitrogen (DON) can be
determined as the difference between TDN and dissolved inorganic
nitrogen (DIN; the sum of all dissolved inorganic nitrogen species).
2 Materials
Use only analytical grade reagents.
2.1 Total Nitrogen
1. Boric acid (H 3 BO 3 ).
2. Concentrated hydrochloric acid (37% HCl).
3. Disodium ethylenediaminetetraacetate dihydrate (Na 2 -EDTA;
C 10 H 14 N 2 Na 2 O 8 ·2H 2 O; e.g., Titriplex
® III).
4. N-(1-naphtyl)-ethylenediamine dihydrochloride (C 10 H 7 NHCH 2
· CH 2 · NH 2 · 2HCl).
5. Potassium peroxodisulfate (K 2 S 2 O 8 ) with low nitrogen content (e.g., Merck 1.05092).
6. Sodium hydroxide (NaOH).
7. Sulfanilamide (NH 2 · C 6 H 6 · SO 2 · NH 2 ).
8. Vanadium chloride (VCl 3 ).
9. Ultrapure water (e.g., Milli-Q).
10. 25 ml reaction flasks with screw caps (e.g., Pyrex containers).
11. 10 ml reaction tubes with screw caps (e.g., Pyrex containers).
12. 50 ml graduated cylinders.
13. 50–1000 ml volumetric flasks.
14. 100–1000 ml storage bottles.
15. Spatulas.
16. Adjustable pipettes and pipette tips.
17. 1 cm plastic cuvettes or flow-through cuvette.
18. Analytical balance.
19. Autoclave.
20. Oven capable of being maintained at 45
C.
21. Refrigerator.
22. Spectrophotometer or automatic analyzer.
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Jaana Koistinen et al.
C) catalytic oxidation [1]. PON can be
determined using combustion at higher temperature (~1000
C)
with an oxidation catalyst followed by reduction to N 2
(or determined as the difference between TN in unfiltered and
filtered samples) [1]. Dissolved organic nitrogen (DON) can be
determined as the difference between TDN and dissolved inorganic
nitrogen (DIN; the sum of all dissolved inorganic nitrogen species).
2 Materials
Use only analytical grade reagents.
2.1 Total Nitrogen
1. Boric acid (H 3 BO 3 ).
2. Concentrated hydrochloric acid (37% HCl).
3. Disodium ethylenediaminetetraacetate dihydrate (Na 2 -EDTA;
C 10 H 14 N 2 Na 2 O 8 ·2H 2 O; e.g., Titriplex
® III).
4. N-(1-naphtyl)-ethylenediamine dihydrochloride (C 10 H 7 NHCH 2
· CH 2 · NH 2 · 2HCl).
5. Potassium peroxodisulfate (K 2 S 2 O 8 ) with low nitrogen content (e.g., Merck 1.05092).
6. Sodium hydroxide (NaOH).
7. Sulfanilamide (NH 2 · C 6 H 6 · SO 2 · NH 2 ).
8. Vanadium chloride (VCl 3 ).
9. Ultrapure water (e.g., Milli-Q).
10. 25 ml reaction flasks with screw caps (e.g., Pyrex containers).
11. 10 ml reaction tubes with screw caps (e.g., Pyrex containers).
12. 50 ml graduated cylinders.
13. 50–1000 ml volumetric flasks.
14. 100–1000 ml storage bottles.
15. Spatulas.
16. Adjustable pipettes and pipette tips.
17. 1 cm plastic cuvettes or flow-through cuvette.
18. Analytical balance.
19. Autoclave.
20. Oven capable of being maintained at 45
C.
21. Refrigerator.
22. Spectrophotometer or automatic analyzer.
82
Jaana Koistinen et al.