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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

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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.

Additional Publication Details

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
Edition:
-
Year Published:
1995
Language:
ENGLISH
Publisher:
U.S. Geological Survey : Earth Science Information Center, Open-File Reports Section [distributor],
Description:
iv, 16 p. :ill. ;28 cm.