ORBECO SP600, Instruction Manual, Page: 189 / 334

187
SP600 Spectrophotometer 01/2008
1.1 Methods
16. Place the vial (the blank) in the sample chamber making
sure that the marks are aligned.
17. Press ZERO key.
Wait for a
reaction period of 5 minutes
.
After the reaction period is finished the measurement starts
automatically.
18. Remove the vial from the sample chamber.
19. Place the vial (the sample, Note 10) in the sample
chamber making sure that the marks are aligned.
20. Press
TEST
key.
The result is shown in the display in mg/l Nitrogen.
Notes:
1. Appropriate safety precautions and a good lab technique should be used during the
whole procedure.
2. Use a funnel to add the reagent.
3. Wipe off any Persulfate reagent that may get on the lid or the tube threads.
4. Volumes for samples and blank should always be metered by using 2 ml volumetric
pipettes (class A).
5. One blank is sufficient for each set of samples.
6. The reagent may not dissolve completely.
7. It is very important to remove the vials from the reactor after exactly 30 minutes.
8. The reagent will not completely dissolve.
9. Hold the vial in a vertical position with the cap pointing up. Turn the vial upside-down.
Wait for all of the solution to flow down to the cap. Return the vial to the upright
position. Wait for all the solution to flow to the bottom of the vial. This process is one
inversion; 10 inversions = approx. 30 seconds.
10. After zero calibration with the blank it is possible to measure several samples.
11. Great quantities of nitrogen free, organic compounds which are included in some
water samples may reduce the effectiveness of the digestion by reacting with the
Persulfate reagent. Samples which are well known to contents great quantities of
organic compounds must be diluted and digestion and measurement must be repeated
for checking the effectiveness of the digestion.
12. Application: for water, wastewater and seawater
13. Interferences:
Interfering substances that resulted in a concentration change of 10%:
Bromide more than 60 mg/l and Chloride more than 1000 mg/l produce positive
interferences.
TN = Total Nitrogen
14.
prepare Zero
press ZERO
Zero accepted
prepare Test
press TEST
Countdown
5:00
N
NH
4
NH
3