NEMI Method Summary

Method Summary Information

Method Number: 130.2 Media: WATER
Revision: Issued 1971; Editorial Revision 1978 and 1982
Method Source: U.S. EPA National Exposure Research Laboratory (NERL) [formerly EMSL]
Analytes in this method
Subcategory: INORGANIC
Official Name: Hardness, Total (mg/L as CaCO3)(Titrimetric, EDTA)
Descriptive Name Total Hardness of Water by Titrimetry
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)
52151 Byte file
Brief Method
Summary:
 Eriochrome Black T (EBT) indicator is added to the sample, and EDTA (ethylenediamine tetraacetate) is titrated into the sample. EBT has a red color in the presence of free calcium and magnesium ions. As EDTA is added to the sample it complexes (sequesters) the ions. In the absence of free calcium and magnesium the EBT will turn blue indicating the endpoint of titration.
Scope And
Application:
 This method determines total hardness in drinking, surface, and saline waters; and domestic and industrial wastes.
Applicable
Conc Range:
 Method is suitable for all concentration levels.
Interferences: (1) A number of metal ions may cause fading or indistinct end points (Standard Methods 2340C provides a listing of interfering metals and their potential effects). (2) Suspended or colloidal organic matter can interfere with the endpoint.
QC Requirements: not included
Sample Handling: Collect at least a 100 mL sample in either glass or plastic bottles. Preserve samples by adding HNO3 until the pH is < 2. Store samples at 4oC until analysis. Analyze samples within 6 months.
Max Holding Time:
 6 months
 
Relative Cost: Less than $50
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