Formazin Standards; Preparation Of Dilution Water; Preparation Of 4000 Ntu Formazin Stock Solution; Preparation Of Dilutions From The 4000 Ntu Formazin Stock Solution - Aqualytic AL250T-IR Mode D'emploi

Formazin Standards

GB

Preparation of dilution water

Obtain at least 1000 ml of high quality water (e.g. distilled, demineralised or deionised water).
Check the turbidity of the dilution water before use. If the turbidity is greater than 0.5 NTU
(FNU) the water should be filtered with membrane filter (0.1 µm). Clean the required glassware
with 1:1 hydrochloric acid and rinse several times with the dilution water.

Preparation of 4000 NTU Formazin Stock Solution

In lieu of preparation we recommend using a 4000 NTU Stock Solution that is available from
specialised suppliers because these standards are high quality and you do not have to handle
the raw materials.
Caution: Please observe the handling instructions of the MSDS. Gloves, goggles and
breathing equipment must be worn!
To prepare a Formazin Stock Solution from raw materials:
1. Dissolve 0.5 g Hydrazine sulfate (NH
2. Dissolve 5.0 g Hexamethylentetramine in 40 ml dilution water.
3. Transfer both solutions quantitativ to a 100 mL volumetric flask and fill to the mark with
dilution water.
4. Mix the solution thoroughly.
5. Allow this solution to stand for at least 24 hours at 25 ± 3°C (77 ± 5°F) in a dark place
(brown glass bottle).
6. The turbidity is developed over this period.
The Formazin Stock Solution has a maximum shelf life of 1 year if stored correctly (in a dark
place). The Production of a Formazin Stock Solution is described in "EN ISO 7027" and
"Standard Methods for Examination of Water and Wastewater".
Preparation of dilutions from the 4000 NTU Formazin Stock
Solution
To prepare the dilutions from a 4000 NTU Formazin Stock Solution and dilution water:
Standard
20 NTU
200 NTU
800 NTU
Use class A volume pipette and glass flasks.
Use dilution water for the < 0.1 NTU standard.
AL250T IR_4 01/2016
) H SO
2 2 2
Step 1
Add 100 ml of dilution
water to a clean
200 ml volumetric
flask.
Add 50 ml of dilution
water to a clean
100 ml volumetric
flask.
Add 50 ml of dilution
water to a clean
100 ml volumetric
flask.
in 40 ml dilution water.
4
Step 2
Pipette 1.00 ml well
mixed 4000 NTU
Formazin Stock
Solution to this
200 ml flask.
Pipette 5.00 ml well
mixed 4000 NTU
Formazin Stock
Solution to this
100 ml flask.
Pipette 20.00 ml
well mixed 4000
NTU Formazin Stock
Solution to this
100 ml flask.
Step 3
Fill to the mark with
dilution water. Close
and mix the flask.
Fill to the mark with
dilution water. Close
and mix the flask.
Fill to the mark with
dilution water. Close
and mix the flask.
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