37
Liquid reagent procedure
• Add 3 drops of HI 93701A-T DPD1 indicator, 3 drops of
HI 93701B-T DPD1 buffer and 1 drop of HI 93701-C to another
cuvet. Shake gently before adding 10 mL of unreacted sample.
Replace the cap and shake gently again.
• Reinsert the cuvet into the instrument.
• Wait for approximately 30 seconds and then press READ. The
display will show "SIP" during measurement.
• The instrument directly displays concentration in mg/L of free or
total chlorine on the Liquid Crystal Display.
Note
: Free and total chlorine have to be measured separately with
fresh unreacted samples following the above procedure if both
values are requested.
INTERFERENCES
Interference may be caused by:
Bromine, Iodine, Fluorine, Ozone, Oxidized manganese and Chro-
mium.
In case of water with hardness greater than 500 mg/L CaCO
3
, shake
the sample for approximately 1 minute after adding the reagent.
Alkalinity above 250 mg/L or acidity above 150 mg/L 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.
Total Chlorine
x 3
x 3
x 1