NEMI Method Summary

Method Summary Information

Method Number: 310.2 Media: WATER
Revision: Issued 1971; Editorial Revision 1974
Method Source: U.S. EPA National Exposure Research Laboratory (NERL) [formerly EMSL]
Analytes in this method
Subcategory: INORGANIC
Official Name: Alkalinity (Colorimetric, Automated, Methyl Orange)
Descriptive Name Alkalinity by Autoanalyzer
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)
27378 Byte file
Brief Method
Summary:
 Methyl orange is used as the indicator in this method because its pH range is in the same range as the equivalence point for total alkalinity, and it has a distinct color change that can be easily measured. The methyl orange is dissolved in a weak buffer at a pH of 3.1, just below the equivalence point, so that any addition of alkalinity causes a loss of color directly proportional to the amount of alkalinity.
Scope And
Application:
 This automated method is applicable to drinking, surface, and saline waters; domestic and industrial wastes.
Applicable
Conc Range:
 10 to 200 mg/L as CaCO3.
Interferences: Sample turbidity and color may interfere with this method. Turbidity must be removed by filtration prior to analysis. Sample color that absorbs in the photometric range used will also interfere.
QC Requirements: None.
Sample Handling: Samples should be refrigerated at 4oC and run as soon as practical. Do not open sample bottle before analysis.
Max Holding Time:
 14 days.
Sample Prep Met None.
Relative Cost: Less than $50
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