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Title: Oxidation of phenolic acid surrogates and target analytes during acid extraction of natural water samples for analysis by GC/MS using EPA method 625

Journal Article · · Environmental Science and Technology; (USA)
DOI:https://doi.org/10.1021/es00015a025· OSTI ID:5547085
; ;  [1]
  1. Environmental Science and Engineering, Inc., Gainesville, FL (USA)

Zero or low phenolic acid surrogate recoveries were occasionally observed in natural water samples analyzed by EPA method 625. These low recoveries were usually caused by the oxidation of the phenolic acid surrogates during acid extraction. Three oxidation products of the phenolic acid surrogates were identified. Iodocyclohexanol, an artifact formed during extraction with cyclohexene-inhibited methylene chloride, was usually present in samples that contained oxidizing agents. Matrix effects on the recoveries of phenolic target analytes were investigated in samples having low phenolic acid surrogate recoveries. The results showed that recoveries for phenols with strong electron-withdrawing substituents, such as a nitro group, were not affected. However, decreased recoveries were observed for phenols having electron-donating substituents or weak electron-withdrawing substituents. It is demonstrated that manganese(III,IV) oxides are most likely the oxidizing agents for the groundwater samples studied. If samples were extracted according to EPA method 625, in the presence of a large amount of manganese, Mn{sup 2+} dissolved in the sample would be oxygenated to manganese(III,IV) oxides during base extraction, which in turn would oxidize the phenols during acid extraction.

OSTI ID:
5547085
Journal Information:
Environmental Science and Technology; (USA), Vol. 25:3; ISSN 0013-936X
Country of Publication:
United States
Language:
English