Hanna Instruments HI 96721C - Manual (Page 15)

15
Calcium (Ca 2+ ): above 10,000 mg/L as CaCO
3
Copper (Cu 2+ ): does not interfere: reagent contains a masking
agent.
Magnesium (Mg 2+ ): above 100,000 mg/L as CaCO
3
Molybdate Molybdenum: above 25 mg/L (as Mo-MoO
4
) (positive error)
Sample containing up to 50 mg/L Mo-MoO
4
may
be measured if a reading is taken after 1 minute
instead of 3 minutes.
High Iron concentrations: up to 200 mg/L do not inhibit color development;
above 200 mg/L color development may be inhibited.
High sulfide concentrations (S 2- ): high sulfide concentrations may interfere
To reduce sulfide: acidify the sample and boil for
about 20 minutes, neutralize and adjust volume
before measurements.
Silica (SiO
2
): above 175 mg/L (as SiO
2
). May slow down color
development (negative error)
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.
• Turn the meter on by pressing ON/OFF.
• Place the CAL CHECK TM Standard
HI 96721-11 Cuvette A into the cuvette
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.