Tintometer Lovibond MD110 Mode D'emploi page 73

Methods
GB
! Zero
Test
O3
RESULT
Notes:
1. Vial cleaning:
As many household cleaners (e.g. dishwasher detergent) contain reducing substances,
the subsequent determination of Ozone may show lower results. To avoid any measure-
ment 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. Preparing the sample:
When preparing the sample, the lost of Ozone, 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 Sulfuric acid resp. 1 mol/l Sodium hydroxide).
4. Exceeding the measuring range:
Concentrations above 6 mg/l Ozone can lead to results showing 0 mg/l. In this case, the
water sample must be diluted with water free of Ozone. 10 ml of the diluted sample
should be mixed with the reagent and the measurement repeated.
5. Oxidising agents such as Bromine, Chlorine etc. interfere as they react in the same way
as Ozone.
Reagent
Set
DPD No. 1 / No. 3
DPD No. 1
DPD No. 3
GLYCINE
MD110_2 03/2018
Close the vial tightly with the cap and swirl gently several times until
the tablet is dissolved.
Add one DPD No. 1 tablet and one DPD No. 3 tablet straight from
the foil into the first cleaned vial and crush the tablets using a clean
stirring rod.
Transfer the contents of the second vial
prepared vial.
Close the vial tightly with the cap and swirl several times until the
tablets are dissolved.
Place the vial in the sample chamber making sure that the
are aligned.
Wait for a reaction period of 2 minutes.
(Countdown can be activated, see page 59)
The method symbol flashes for approx. 3 seconds.
The result 2 is shown in the display.
mg/l Ozon = result 1 – result 2
mg/l Chlorine total = result 2 x 1.477
Form of reagent/Quantity
Tablet / per 100
inclusive stirring rod
Tablet / 100
Tablet / 100
Tablet / 100
(Glycine solution) into the
marks
Order-No.
517711BT
511050BT
511080BT
512170BT
73