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INTERFERENCES
Highly buffered samples (alkalinity above 500 ppm) or with extreme pH may exceed the
buffering capacity of the reagent: neutralize acidic samples with diluted NaOH or alkaline
samples with diluted HCl, prior to addition of the reagent.
Turbidity must be removed by prior filtration.
The following ions may cause negative errors:
cupric ions (Cu
2+
):
above 5 ppm
ferrous ions (Fe
2+
): above 1 ppm
ferric ions (Fe
3+
):
above 2 ppm
VALIDATION PROCEDURE
Use the validation procedure to ensure that the instrument is properly calibrated.
Warning:
Do not validate the instrument with any standard solutions other than the HANNA
CAL
CHECK
TM
Standards, otherwise erroneous results will be obtained. For accurate validation, please
perform test at room temperature: 18 to 25°C (64.5 to 77.0°F)
•
Turn the meter on by pressing
ON/OFF
.
• Press
ZERO/CFM
and the lamp, cuvet
and detector icons will appear on the
display, depending on the measurement
phase.
• Place the
CAL CHECK
TM
Standard
HI 95707-11
Cuvet A into the cuvet
holder and ensure that the notch on the
cap is positioned securely into the groove.
• When the beeper sounds briefly and the
LCD displays dashes, the meter is ready.