TurbiTechw² LR Instruction Manual
13 General Application Notes
13.1 Preparation of Formazin Turbidity Standard
Preparation of Formazin Turbidity Standard for Calibration.
13.1.1 Health & Safety Precautions
The chemicals used when following this procedure are harmful, therefore the correct safety
precautions must be carried out. During handling, avoid inhalation and contact with the eyes or skin.
Wash hands thoroughly after use. Refer to the Manufacture Safety Data Sheets for further details of
the chemicals used.
13.1.2 Method of Preparation
The preparation of a Formazin Turbidity Standard should be carried out with great care. Absolute
cleanliness should be observed at all times to avoid any contamination of the solution.
All water used should be freshly distilled or de-mineralised. During preparation and use, keep the
solution covered to prevent contamination.
•
Dissolve the Hydrazinium Sulphate 10g (32112680) into 1 litre of water. Stir the solution thoroughly.
•
Dissolve the Hexamine 100g (32112630) into 1 litre of water. Stir the solution thoroughly.
•
Pour the above solutions into a 2.5 litre Winchester or similar type amber glass bottle and mix
thoroughly. Allow the mixture to stand undisturbed for 24 hours at 25ºC. The resultant solution will
have a turbidity of 4000 FTU.
•
Prior to use the standard should be mixed thoroughly, i.e. before pouring out the standard, shake the
bottle well.
13.1.3 Preparation of Dilution’s.
The 4000 FTU standard can be used to prepare solutions of lower values by diluting with water. The
formula below can be used to calculate the ratio of water to 4000 FTU standard to produce a solution
of the required value.
W
A
4000
1
W = parts water to 1 part 4000 FTU standard
A = Required FTU value
The Formazin Dilution Chart (table QAP 6.14.4) provides the mixture requirements to make various
solutions using the 4000 FTU standard.
13.1.4 Calibration
When Formazin solutions are used for calibration/testing of sensors, sufficient solution is required such
that the sensor is completely immersed. When using light scatter sensors it is important that the
sensor is positioned away from the sides and bottom of the container to prevent the light being
reflected.
13.1.5 Storage Life
The turbidity standard should be stored in a Winchester bottle and kept in a cool dark place. The bottle
should be labelled to identify its content and also the date of preparation should be recorded. The
4000 FTU standard has a shelf life of one year after which it should be discarded and a fresh solution
should be prepared.
225769IM - Issue - 05 Issue Date 30/04/2019
Page 29 of 34
