Reflectoquant® Nitrite Test Strips, Catalog No. 16973/1
1. Method
In the presence of an acidic buffer, nitrite
reacts with an aromatic amine to form a diazonium salt, which in turn
reacts with N-(1-naphthyl)-ethylenediamine to form a red-violet azo
dye, the concentration of which is determined reflectometrically.
2. Measuring Range and Number of Determinations
| Measuring Range1) |
Number of Determinations |
0.5 - 25.0 mg/l NO2-
0.2 - 7.6 mg/l N
10.9 - 542 mmol/m3 NO2-
or N |
50 |
1) for conversion factors see
section 8
for measurement of concentrations > 25 mg/l
NO2– see section 6
3. Applications
This test is only conditionally suited for the
determination of the nitrite content of seawater samples (false-low
readings).
Sample material:
Industrial water
Wastewater
Water in aquariums
Food
Cooling lubricants
4. Influence of Foreign Substances
This was checked - in the case of interfering
ions up to concentrations of 1,000 mg/l - in solutions containing 10
mg/l NO2–. The concentrations of foreign
substances given in the table lie below the limit at which the
determination is interfered with:
Concentrations of Foreign Substances in mg/l
or %
| Al3+ |
1,000 |
| Ascorbate |
100 |
| BO33- |
1,000 |
| Ca2+ |
1,000 |
| Citrate |
1,000 |
| Cl- |
100 |
| CO32- |
1,000 |
| Cr3+ |
100 |
| CrO42- |
10 |
| Cu2+ |
1,000 |
|
| Fe2+ |
100 |
| Fe3+ |
100 |
| K+ |
1,000 |
| Mg2+ |
1,000 |
| Mn2+ |
100 |
| NO2- |
1,000 |
| Oxalate |
1,000 |
| PO43- |
1,000 |
| SO32- |
100 |
| Tartrate |
1,000 |
|
| EDTA |
1,000 |
| Anionic Surfactants2) |
100 |
| Cationic Surfactants3) |
1,000 |
| Nonionic Surfactants4) |
1,000 |
| H2O2 |
100 |
| Na2SO4 |
20% |
|
1)In cases in which the nitrite
concentration is higher, eliminate nitrite ions acc. to section 6
2)tested with Na-dodecyl sulfate
3)tested with N-cetylpyridinium
chloride
4)tested with polyvinylpyrrolidone
5. Reagents and auxiliaries
| Store originally sealed pack in
refrigerator. Opened pack: store closed tube outside refrigerator in
a cool and dry place. The analytic test strips are stable at least
up to the date stated on the pack when stored in these conditions. |
Package contents:
Tube containing 50 analytical test strips
Bar code strip
Other reagents:
EM Quant® Nitrite Test, Cat. No.
10007, measuring range 2-80 mg/l NO2–
colorpHast® Universal indicator strips pH 0-14. Cat. No 9590
Sodium acetate GR, Cat. No.SX0255
Tartaric acid GR, Cat. No. TX0010
Nitrite standard solution ready for use, 1,000
mg/l NO2–, Cat. No. 19899
6. Preparation
· Check whether the nitrite content is
within the measuring range. Use the EM Quant® Nitrite
Test as a guide. Samples containing more than 25.0 mg/l NO2–
must be diluted with distilled water.
· The pH must be within the range 1-13.
Check with universal indicator strips. If pH is lower than 1,
buffer with sodium acetate; if greater than 13, adjust to approx. 3-5
with tartaric acid.
7. Procedure
· Observe the instructions for the RQflex
Reflectometer.
The following applies to the Nitrite Test:
Measurement procedure A. Stored reaction
time: 15 sec.
- Remove 1 analytical test strip and immediately
reclose the tube.
- Press START button of the reflectometer and
at the same time immerse both reaction zones of the test
strip in the sample solution (15-30°C) for approx. 2 sec.
- Shake off excess liquid from the test strip
- As soon as the beeper sounds (5 sec. before
end of reaction time), insert the test strip all the way into the
strip adapter with the reaction zones facing the display.
- Read off the result from the display. The
result is automatically stored.
Note:
- If the test strip is inserted into the
adapter after the reaction time has expired, renewed depression of
the START button will result in a false-high reading of the nitrite
concentration.
- At the end of each workday, cleanse the
strip adapter thoroughly with water or ethanol.
8.Conversions
| units required= |
units given x |
conversion factor |
| mmol/m3 NO2- |
mg/l NO2- |
21.7 |
| mg/l N |
mmol/m3 NO3-
or n |
0.304 |
| mg/l NO2- |
mg/l N |
3.28 |
9. Method control
To check analytical test strips, equipment and
procedure:
Dilute nitrite standard solution to 10 mg/l NO2–
and analyze as described in section 7. |
MSDS
(Material Safety Data Sheet)
