Hanna Instruments HI 96707C - Manual (Page 15)

15
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.
• When the beeper sounds briefly and the
LCD displays dashes, the meter is ready.
• Place the CAL CHECK TM Standard
HI 96707-11 Cuvette A into the cuvette
holder and ensure that the notch on the
cap is positioned securely into the groove.
• Press ZERO/CFM and the lamp, cuvette
and detector icons will appear on the
display, depending on the measurement
phase.