Reflectoquant® Nitrate Test, Catalog No. 16971/1
1. Method
Nitrate is reduced to nitrite by a reduction
agent. In the presence of an acidic buffer, this nitrate 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 |
5 - 225mg/l NO3-
1.1 - 50.8mg/l N
80.5 - 3.622mmol/m3 NO3-M or N |
50 |
1) for conversion factors see section 8
for measurement of concentrations > 225 mg/l
NO3– see section 6
3. Applications
Sample Material:
Groundwater, wellwater and drinking water
Spring water and mineral water
Industrial water,wastewater, percolating water
Water in aquariums
Pressed plant and fruit juices
Food, animal fodder
Soils and fertilizers
This test is only conditionally suited for the
determination of the nitrate content of seawater samples (false-low
readings).
4. Influence of Foreign Substances
This was checked - in the case of interfering
ions up to concentrations of 1,000mg/l - in solutions containing 100
mg/l and 0 mg/l NO3-. 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
%
| A13+ |
1,000 |
| Ascorbate |
1,000 |
| BO33- |
1,000 |
| Ca2+ |
1,000 |
| Citrate |
1,000 |
| Cl- |
500 |
| CO32- |
1,000 |
| Cr3+ |
100 |
| CrO42- |
10 |
| Cu2+ |
1 |
|
| Fe2+ |
10 |
| Fe3+ |
10 |
| K+ |
1,000 |
| Mg2+ |
1,000 |
| Mn2+ |
1,000 |
| NO2- |
0.51) |
| Oxalate |
1,000 |
| PO43- |
1,000 |
| SO32- |
10 |
| Tartrate |
1,000 |
|
| EDTA |
1,000 |
| Anionic surfactants2) |
10 |
| Cationic surfactants3) |
10 |
| Nonionic surfactants4) |
1,000 |
| H2O2 |
10 |
| Na2SO4 |
1% |
|
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
The analytical test strips are stable up to the dated stated on the pack when stored in the
closed tube at +2 to +8°C.
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
Amidosulfonic acid GR, Cat No. SX1140
EM Quant® Nitrate Test, Cat. No.
10020 or 10050, measuring range 10-500 mg/l NO3-
Sodium acetate GR, Cat. No. SX0265
Tartaric acid GR, Cat. No. TX0010
Nitrate standard solution ready for use, 1,000mg/l NO3-, Cat. No. 19811
6. Preparation
- Extract solid sample materials by an
appropriate method.
- If nitrite is suspected, check the nitrite
content using the EM Quant® Nitrite Test.
If necessary eliminate interfering nitrite ions:
To 5ml of sample (pH <10) add 5 drops of a
10% aqueous amidosulfonic acid solution and shake several times.
- Check whether the nitrate content is
within the measuring range. Use the EM Quant® Nitrate
Test as a guide. Samples containing more than 225 mg/l NO3- must
be diluted with distilled water.
- The pH must be within the range 1-12.
Check with universal indicator strips. If pH is lower than 1,
buffer with sodium acetate; if greater than 12, adjust to approx. 3-5
with tartaric acid.
7. Procedure
Observe the instructions for the RQflex
Reflectometer.
The following applies to the Nitrate Test:
Measurement procedure A.
Stored reaction time: 60 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.
- Allow excess liquid to run off via the long edge of the strip onto
an absorbent paper towel.
- Approximately 10 seconds before the end of the 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 in mg/l
NO3-. 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 may result in a false reading of the nitrate
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 |
| mg/l NO3- or N |
mg/l NO3- |
0.226 |
| mg/l NO3- |
mg/l NO3- or N |
4.43 |
9.Method Control
To check analytical test strips, equipment and
procedure:
Dilute nitrate standard solution to 50 mg/l NO3-
and analyze as described in section 7. |
MSDS
(Material Safety Data Sheet)
