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Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory-Determination of methylene blue active substances by spectrophotometry

Open-File Report 95-189
By: , , , , and 
https://doi.org/10.3133/ofr95189

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Abstract

A method for the determination of methylene blue active substances in whole-water samples by liquid-liquid extraction and spectrophotometric detection is described. Sulfate and sulfonate-based surfectants are reacted with methylene blue to form a blue-colored complex. The complex is extracted into chloroform, back-washed with an acidified phosphate-based buffer solution, and measured against external standards with a probe spectrophotometer. The method detection limt for routine analysis is 0.02 milligram per liter. The precision is plus/minus 10 percent relative standard deviation. The positive bias from nitrate and chloride and U.S. Geological Survey method O-3111-83 for methylene blue active substances is minized by adding a back-washing step.

Suggested Citation

Burkhardt, M.R., Cinotto, P., Frahm, G.W., Woodworth, M.T., Pritt, J.W., 1995, Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory-Determination of methylene blue active substances by spectrophotometry: U.S. Geological Survey Open-File Report 95-189, iv, 16 p., https://doi.org/10.3133/ofr95189.

ISSN: 2331-1258 (online)

Publication type Report
Publication Subtype USGS Numbered Series
Title Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory-Determination of methylene blue active substances by spectrophotometry
Series title Open-File Report
Series number 95-189
DOI 10.3133/ofr95189
Year Published 1995
Language English
Publisher U.S. Geological Survey
Contributing office(s) National Water Quality Laboratory
Description iv, 16 p.
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