Calibration Procedure - Hanna Instruments HI 98713 Instruction Manual

CALIBRATION PROCEDURE

CALIBRATION PROCEDURE
CALIBRATION PROCEDURE CALIBRATION PROCEDURE CALIBRATION PROCEDURE
HI 98713 has a powerful calibration function that compensates for LED aging or changing. The
calibration can be done using the suplied calibration solutions or user prepared standards.
HI 98713 turbidimeter is supplied with 4 AMCO standards: <0.1 FTU, 15 FTU, 100 FTU and 750
FTU. The Hanna standards are specially designed for this instrument. The turbidity standards have a
shelf life and should not be used after the expiration date.
Alternatively, formazin standards can be used. It is recommended that the prepared calibration
solutions to be close to the default calibration points.
The first point should be near 0 FTU. The second point can be chosen between 10 and 20 FTU, the
third point between 50 and 150 FTU and the fourth point between 600 and 900 FTU.
FORMAZIN PREPARATION
In order to prepare formazin 4000 FTU stock solution, follow the next procedure:
Solution I
Dissolve 1.000 grams of hydrazine sulfate, (NH
deionized water and dilute to 100 mL in a volumetric flask.
Warning: Handle hydrazine sulfate with care because it is a carcinogen reagent. Avoid inhalation,
ingestion, or skin contact. Formazin solution can also contain some hydrazine traces.
Solution II
Dissolve 10.000 grams of hexamethylenetetramine, (CH2)
deionized water and dilute to 100 mL in a volumetric flask.
Stock solution Mix 10 mL Solution I and 10 mL Solution II in a flask. Let the stock solution
stays 48 hours at 25±3°C (77±5°F). This will result in a 4000 FTU formazin suspension. It
is very important for the formation of the formazin polymer to maintain the same temperature.
The stock solution (4000 FTU) can be stored up to one year in proper conditions. Store formazin in
amber glass bottle or any UV-light blocking bottle.
To obtain a high quality formazin always use pure reagents and high-purity water.
To prepare the calibration standards, dilute the stock solution with the same high-purity water you
used for the preparation of the stock solution.
The diluted formazin solutions are not stable. They should be used immediately after preparation
and discard immediately after use.
If the prepared formazin is used, enter the actual standard value by pressing UP or DOWN key to edit
the value of the second, third or fourth calibration point.
CALIBRATION
For best results, the measurement techniques must be followed during calibration. If formazin
standards are used, mix the cuvets gently for about 1 minute and then allow the standard to settle for
one more minute before calibration.
Calibration can be performed in two, three or four points. It is possible to interupt calibration
procedure at any time by pressing CAL or ON/OFF.
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H SO , in distilled,
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N , in distilled,
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