NEMI Method Summary

Method Summary Information

Method Number: 360.2 Media: WATER
Revision: Issued 1971
Method Source: U.S. EPA National Exposure Research Laboratory (NERL) [formerly EMSL]
Analytes in this method
Subcategory: INORGANIC
Official Name: Oxygen, Dissolved (Modified Winkler, Full-Bottle Technique)
Descriptive Name Dissolved Oxygen Using a Modified Winkler Method
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)
38017 Byte file
Brief Method
Summary:
 The sample is treated with manganous sulfate, potassium hydroxide and potassium iodide, and finally sulfuric acid. The initial precipitate of manganous hydroxide combines with the dissolved oxygen in the sample to form a brown precipitate, manganic hydroxide. Upon acidification, the manganic hydroxide forms manganic sulfate which acts as an oxidizing agent to release free iodine from potassium iodide. The iodine, which is stoichiometrically equivalent to the dissolve oxygen in the sample is then titrated with sodium thiosulfate of phenylarsine oxide.
Scope And
Application:
 This method determines dissolved oxygen in most wastewaters and streams that contain nitrate nitrogen and not more than 1 mg/L of ferrous iron.
Applicable
Conc Range:
 Not Available.
Interferences: Chemical Agents: Oxidizing and reducing agents, nitrate ion, ferrous iron, and organic matter could effect test results. Modifications to the original Winkler procedure have overcome many interferences. In addition, the dissolved oxygen probe (EPA Method 360.1) is an alternative procedure which is subject to less interferences.
QC Requirements: None.
Sample Handling: Collect samples in BOD bottles according to method recommendations, and record the temperature. If samples have applicable iron demand or ferrous iron concentration, analyze as soon as possible. If not, samples may be preserved (as described in the method) and analysis may occur between 4 and 8 hours after collection.
Max Holding Time:
 8 hours (preserved) (MCAWW, Table 1).
Sample Prep Met None.
Relative Cost: Less than $50
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