4 CALIBRATION
40
4.6
Turbidity Calibration
There are three calibrating patterns for turbidity, not including automatic zero calibration.
See "4.1 Calibration Patterns and Cycles" (page 17) and select one of the patterns.
See "5.3 Automatic Zero Calibration" (page 78) for automatic zero calibration settings.
<Reference> Making turbidity span calibration solution
Polystyrene latex standard solution (4 FTU)
After shaking commercial polystyrene latex standard solution (100 FTU) thoroughly,
immediately pour the 40 mL solution into a 1000 mL flask, and then fill it with water up to the
gauge line.
Tip
Using the turbidity calibration solution immediately after preparing may cause air bubbles, affecting
the measured value. Let the solution sit for 24 hours before using so that calibration is stable.
Formazine (C
2
H
4
N
2
) (4 FTU)
Quoted form ISO 7027
Formazine is not available commercially, therefore it shall be prepared as follows.
1.
Dissolve 10.0 g of hexamethylenetetramine (C
2
H
12
N
4
) in water and dilute to 100 mL
(Solution A).
2.
Dissolve 1.0 g of hydrazine sulfate (N
2
H
6
SO
4
) in water and dilute to 100 mL
(Solution B).
Note
Hydrazine sulfate is poisonous and may be carcinogenic.
3.
Mix 5 mL of solution A with 5 mL solution B. Leave for 24 hours at 25
C ±3
C. Then
dilute solution to
100 mL with the water.
4.
The turbidity of this stock solution (Solution C) in fomazine turbidity units (FTU) is
400.
5.
This solution is stable for about 4 weeks if stored at a temperature of 25
C ±3
C in
the dark.
6.
Mix 10 mL of solution C in water and dilute to 1000 mL with the water. The turbidity
of this solutionb in FTU is 4.
Summary of Contents for TW-100
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