39
METHOD PROCEDURES
39
39
CHLORINE DIO
XIDE
, RAPID METHOD
10.4. CHLORINE DIOXIDE, RAPID METHOD
SPECIFICATIONS
Range
0.00 to 2.00 mg/L (as ClO
2
)
Resolution
0.01 mg/L
Accuracy
±0.10 mg/L ±5% of reading at 25 °C
Light Source
LED with narrow band interference filter @ 525 nm
Method
Adaptation of Standard Methods for the Examination of Water and Wastewater,
18
th
Edition, 4500 ClO
2
D
REQUIRED REAGENT
Code Description
Quantity
HI96779A-0
Chlorine Dioxide Reagent A
5 drops
HI96779B-0
Chlorine Dioxide Reagent B
1 packet
REAGENT SETS
HI96779-01
Reagents for 100 tests
HI96779-03
Reagents for 300 tests
For other accessories see ACCESSORIES section.
PRINCIPLE
The reaction between the Chlorine Dioxide and DPD indicator causes a pink tint in the sample, the
addition of glycine as a masking agent inhibits the response of free chlorine.
APPLICATION
Drinking water, tap water, treated water
SAMPLING PROCEDURE
Collect the sample in a clean glass bottle and analyze it immediately. Chlorine dioxide is a strong
oxidizing agent and is unstable in water.
SIGNIFICANCE & USE
Chlorine Dioxide is a commonly-used alternative to chlorine (Cl
2
) as a water disinfectant. The
Chlorophenol Red method (non-rapid method) reacts specifically with chlorine dioxide with little
interference from free chlorine or chloramines, but the method procedure is cumbersome. The Chlorine
Dioxide Rapid Method based on the DPD (N,N-diethyl-p-phenylenediamine) indicator is a much
simpler method by comparison, but it is susceptible to interference from other oxidizers. Glycine
(Reagent A) is able to convert free chlorine to chloroaminoacetic acid without affecting the analysis
of chlorine dioxide content.