English (GB)
26
7.10 CyA TEST (cyanuric acid),
2 - 160 mg/l CyA
7.10.1 Important notes
1. Use deionised water or tap water free of cyanuric acid.
2. If cyanuric acid is present, a cloudy solution will occur. Small
single particles are not necessarily caused by cyanuric acid.
3. Dissolve the tablet completely by swirling the vial for approx.
one minute. Undissolved particles of the tablet can cause
results that are too high.
7.10.2 Measurement
7.11 Fluoride, 0.05 - 2 mg/l F
-
7.11.1 Important notes
1. The same batch of
SPADNS reagent
solution must be used for adjustment and test. The
adjustment process needs to be performed for each new
batch of
SPADNS reagent
solution (see Standard Methods
20th, 1998, APHA, AWWA, WEF 4500 F D., pages 4-82).
The procedure is described in section
.
2. During adjustment and test the same vial should be used for
zeroing and test, as different vials may exhibit minor
tolerances.
3. The calibration solution and the water samples to be tested
should have the same temperature (± 1 °C).
4. As the test result is highly dependent on exact sample and
reagent volumes, the sample and reagent volumes should
always be metered using a 10 ml and 2 ml volumetric pipette
(class A), respectively.
5. The accuracy of the test methods decreases above a level of
1.2 mg/l fluoride. Although the results are sufficiently accurate
for most applications, even more exact results can be
achieved by 1:1 dilution of the sample prior to use and
subsequent multiplication of the result by 2.
6.
SPADNS reagent
solution contains arsenite.
Chlorine concentrations up to 5 mg/l do not interfere.
7. Seawater and wastewater samples must be distilled.
8. It is convenient to use special vials with larger volume.
7.11.2 Measurement
7.12 Hydrogen peroxide,
0.03 - 3 mg/l H
2
O
2
7.12.1 Important notes
1. Vial cleaning:
As many household cleaners (e.g. dishwasher detergent)
contain reducing substances, the subsequent determination of
hydrogen peroxide may show lower results. To avoid any
measurement errors, only use glassware free of chlorine
demand. Preparation: Put all applicable glassware into
sodium hypochlorite solution (0.1 g/l) for one hour, then rinse
all glassware thoroughly with deionised water.
2. When preparing the sample, the escape of hydrogen peroxide
gases, e.g. by pipetting or shaking, must be avoided. The
analysis must take place immediately after taking the sample.
3. The DPD colour development is carried out at a pH value of
6.2 to 6.5. The reagent tablet therefore contains a buffer for
the pH adjustment. Strong alkaline or acidic water samples
must be adjusted between pH 6 and pH 7 before the tablet is
added. Use 0.5 mol/l sulphuric acid and 1 mol/l sodium
hydroxide, respectively.
4. For concentrations between 3 and 5 mg, the photometer
shows that the measuring range (Overrange) has been
exceeded. Concentrations above 5 mg/l hydrogen peroxide
can lead to results showing 0 mg/l. In this event, the water
sample must be diluted with water free of hydrogen peroxide.
10 ml of the diluted sample should be mixed with the reagent
and the measurement repeated (plausibility test).
5. All oxidising agents in the samples interfere, as they react in
the same way as hydrogen peroxide.
1. Fill a clean vial (
∅
24) with 5 ml of the
water sample and 5 ml of deionised
water using the plastic syringe. See
section
, note 1. Close tightly with
the cap.
2. Place the vial in the sample chamber
correctly. See fig.
3. Press the [Zero] key.
4. Remove the vial from the sample
chamber.
5. Add one
CyA-TEST
tablet
(No
) straight from the foil to
the prepared water sample and crush the
tablet using a clean stirring rod.
6. Close the vial tightly with the cap and
swirl gently several times until the tablet
is dissolved. See section
notes 2 and 3.
7. Place the vial in the sample chamber
correctly. See fig.
Press the [Test] key.
The result is shown in the display in mg/l
CyA.
1
6
0
prepare Zero
press ZERO
Zero accepted
prepare Test
press TEST
∅
24
1
7
0
Observe section
!
1. Fill a clean vial (
∅
24) (note 8) with
exactly 10 ml of water sample (note 4).
Close tightly with the cap.
2. Place the vial in the sample chamber
correctly. See fig.
.
3. Press the [Zero] key.
4. Remove the vial from the sample
chamber.
5. Add exactly 2 ml
SPADNS reagent
solution (No
) to the water
sample. Caution: Vial is filled up to the
top (note 8)!
6. Close the vial tightly with the cap and
swirl several times to mix the contents.
7. Place the vial in the sample chamber
correctly. See fig.
.
8. Press the [Test] key.
The result is shown in the display in mg/l
fluoride.
prepare Zero
press ZERO
Zero accepted
prepare Test
press TEST
∅
24
2
1
0
Summary of Contents for DIT-M
Page 34: ...34...
