EPA-NERL: 425.1: Surfactants by Colorimetry
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Official Method Name
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Methylene Blue Active Substances (MBAS) (Colorimetric) |
|---|---|
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Current Revision
| Issued 1971 |
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Media
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WATER |
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Instrumentation
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Spectroscopy (Colorimetry; Photometry) |
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Method Subcategory
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Organic |
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Method Source
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Citation
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Brief Method Summary
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Methylene blue reacts with anionic-type surface active materials to form a blue colored sample. The salt is extracted with chloroform and intensity of the color in the extract is proportional to the concentration of methylene blue active substances (surfactants). |
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Scope and Application
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This method determines methylene blue active substances (surfactants) in drinking water, surface water; domestic and industrial wastes. The method is not applicable to saline waters. |
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Applicable Concentration Range
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0.025 to 100 mg/L linear alkyl sulfonate. |
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Interferences
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Compounds: Many compounds other than surfactants can react with methylene blue, including organically bound sulfates, sulfonates, carboxylates, phosphates, phenols, cyanates, thiocyanates, and some inorganic ion such as nitrates and chlorides. However, the occurrence of these compounds is usually rare (with the exception of chlorides). |
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Quality Control Requirements
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None. |
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Sample Handling
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None. |
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Maximum Holding Time
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48 Hours (MCAWW, Table 1). |
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Relative Cost
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Less than $50 |
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Sample Preparation Methods
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None. |
