NEMI Method Summary

Method Summary Information

Method Number: 330.1 Media: WATER
Revision: Issued 1974; Editorial Revision 1978
Method Source: U.S. EPA National Exposure Research Laboratory (NERL) [formerly EMSL]
Analytes in this method
Subcategory: INORGANIC
Official Name: Chlorine, Total Residual (Titrimetric, Amperometric)
Descriptive Name Total Residual Chlorine by Titration
Source Info: U.S.EPA National Exposure Research Laboratory (NERL)
Microbiological and Chemical Exposure Assessment Research Division (MCEARD)
[formerly the Environmental Monitoring Systems Laboratory (EMSL), Cincinnati, OH]
26 West Martin Luther King Drive
Cincinnati, Ohio 45268-0001
Fax: 513-569-7757
email: DWmethods.help@epa.gov
Citation: Methods for the Chemical Analysis of Water and Wastes (MCAWW) (EPA/600/4-79/020)
23924 Byte file
Brief Method
Summary:
 Chlorine (hypochlorite ion, hypochlorous acid) and chloramines stoichiometrically liberate iodine from potassium iodide at pH 4 or less. The iodine is titrated with standard reducing agent such as sodium thiosulfate or phenylarsine oxide using an amperometer to determine the end point. The results are calculated as mg/L Cl even though the actual measurement is of total oxidizing power because chlorine is the dominant oxidizing agent present.
Scope And
Application:
 The amperometric titration method is applicable to all types of waters and wastes that do not contain a substantial amount of organic matter.
Applicable
Conc Range:
Interferences: Stirring can lower chlorine values by volatilization.
If dilution is necessary, it must be done with distilled water which is free of chlorine, chlorine-demand, and ammonia. Copper and silver poison the electrode.
QC Requirements: None.
Sample Handling: Store at 4oC and analyze as soon as possible.
Max Holding Time:
 Analyze Immediately.
Sample Prep Met None.
Relative Cost: Less than $50
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