YSI 9300 Photometer - Manual (Page 140)

PHOTOMETER TEST INSTRUCTIONS
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Chlorine dioxide is increasingly being chosen ahead of chlorine for use in many
applications where it is believed to have several advantages.
Chlorine dioxide is used in water disinfection, where its ability to disrupt biofilm in
pipe work makes it useful against certain waterborne micro organisms such as
Legionella. Chlorine dioxide is also used in the food industry for control of micro
organisms in fruit washing and is popular in the pulp and paper industry as a
bleaching agent. The USEPA has rated chlorine dioxide as the best available
technology for paper pulp bleaching due to its low environmental impact.
Chlorine dioxide may be generated on-site either electrolytically or by reacting
chlorine with sodium chlorite solution. Water treated with chlorine dioxide may
therefore also contain amounts of chlorine and chlorite. For the control of water
treatment systems it is necessary to determine chlorine dioxide in the presence
of these other residuals.
The YSI Chlorine Dioxide method provides a specific method of determining chlorine
dioxide in treated water, in the presence of free and combined chlorine and chlorite.
Method
In the YSI Chlorine Dioxide test, Lissamine Green B is bleached under alkaline
conditions by chlorine dioxide. An ammonium salt is used to prevent any
interference by chlorine. This method can determine chlorine dioxide accurately
in the presence of free and complexed chlorine, chlorite, chlorate, ozone,
bromine and permanganate.
Reagents and Equipment
YSI Chlordiox Buffer Tablets
YSI Chlordiox HR Tablets
YSI 9300 or 9500 Photometer
YSI Round Test Tubes, 10 ml glass (PT 595)
Photometer Method
AUTOMATIC
WAVELENGTH
SELECTION
0 – 20 mg/l
PHOT.76.AUTO