User Manual
94 95
Dissolved Oxygen
SPECIFICATIONS
Range 0.0 to 10.0 mg/L
Resolution 0.1 mg/L
Accuracy ±0.4 mg/L ±3% of reading at 25 °C
Typical EMC ± 0.1 mg/L
Deviation
Light Source Tungsten lamp with narrow band interference filter @ 420 nm
Method Adaptation of the
Standard Methods for the Examination of Water and Wastewater,
18
th
edition
,
Azide modified Winkler method. The reaction between dissolved oxygen
and the reagents causes a yellow tint in the sample.
REQUIRED REAGENTS
Code Description Quantity
HI 93732A-0 Reagent A 5 drops
HI 93732B-0 Reagent B 5 drops
HI 93732C-0 Reagent C 10 drops
REAGENT SET
HI 93732-01 Reagents for 100 tests
HI 93732-03 Reagents for 300 tests
For other accessories see page 128.
MEASUREMENT PROCEDURE
• Select the
Dissolved
Oxygen
method using the procedure described in
the
Method Selection
section (see page 12).
• Fill one 60 mL glass bottle completely with the unreacted sample.
• Replace the cap and ensure that a small part of the sample spills
over.
• Remove the cap and add 5 drops of HI 93732A-0 and 5 drops of
HI 93732B-0.
• Add more sample, to fill the bottle completely. Replace the cap
again and ensure that a part of the sample spills over. This is to
make sure that no air bubbles have been trapped inside, which
could alter the reading.
• Invert several times the bottle. The sample becomes orange-yellow
and a flocculent agent will appear.
DISSOLVED OXYGEN
• Reinsert the cuvette into the instrument.
• Press Timer and the display will show the countdown prior to the measurement or, alternatively, wait
for 6 minutes and press Read. When the timer ends the meter will perform the reading. The instrument
displays concentration in mg/L of nitrite.
• Press s or t to access the second level functions.
• Press the Chem Frm key to convert the result in mg/L of nitrogen-nitrite (NO
2
¯-N) and sodium nitrite
(NaNO
2
).
• Press s or t to return to the measurement screen.
INTERFERENCES
Interference may be caused by the following ions:
ferrous, ferric, cupric, mercurous, silver, antimonious, bismuth, auric, lead, metavanadate and chloroplatinate.
Strongly reducing and oxidizing reagents.
High levels of nitrate (above 100 mg/L) could yield falsely high readings due to a minute amount of
reduction to nitrite that could occur at these levels.
Nitrite LR