Hanna Instruments HI 95725C - Manual (Page 8)

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INTERFERENCES
• Positive error: - Bromine
- Chlorine dioxide
- Iodine
- Ozone
- Oxidized Manganese and Chromium
• Alkalinity above 250 mg/L CaCO
3
or acidity above 150 mg/L CaCO
3
will not reliably develop
the full amount of color or it may rapidly fade.
To resolve this, neutralize the sample with diluted HCl or NaOH.
• In case of water with hardness greater than 500 mg/L CaCO
3
, shake the sample for
approximately 2 minutes after adding the powder reagent.
Chlorine
• For free chlorine measurement: add 3 drops
of HI 93701A-T DPD1 indicator and 3
drops of HI 93701B-T DPD1 buffer to an
empty cuvet.
Immediately add 10 mL of unreacted
sample. Replace the cap and shake gently.
• Immediately reinsert the cuvet into the
holder and ensure that the notch on the
cap is positioned securely into the groove.
• Press READ and “SIP” will blink during
measurement.
• The instrument directly displays
concentration in mg/L of free chlorine on
the Liquid Crystal Display.
• Then, for total chlorine measurement, remove
the cuvet and add to the reacted sample 3
drops of HI 93701C-T DPD3 solution.
Replace the cap and swirl gently.
• Reinsert the cuvet into the holder and
ensure that the notch on the cap is
positioned securely into the groove.
• Wait for 2’ and 30” then press READ and
“SIP” will blink during measurement.
• The instrument directly displays
concentration in mg/L of total chlorine on
the Liquid Crystal Display.
• Remove the cuvet.
Chlorine