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

Burkhardt, Mark R.; Cinotto, Pete J.; Frahm, Galen W.; Woodworth, Mark T.; Pritt, Jeffrey W.

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.

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USGS Numbered Series

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17340

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Burkhardt, Mark R.; Cinotto, Pete J.; Frahm, Galen W.; Woodworth, Mark T.; Pritt, Jeffrey W.

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ENGLISH

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iv, 16 p. :ill. ;28 cm.

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U.S. Geological Survey : Earth Science Information Center, Open-File Reports Section [distributor],

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Open-File Report

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OFR

Citation Series Number:

95-189

Citation Search Results Text:

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of methylene blue active substances by spectrophotometry; 1995; OFR; 95-189; Burkhardt, Mark R.; Cinotto, Pete J.; Frahm, Galen W.; Woodworth, Mark T.; Pritt, Jeffrey W.