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Aqueous photolysis of niclosamide

Journal of Agricultural and Food Chemistry

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Abstract

The photodegradation of [14C]niclosamide was studied in sterile, pH 5, 7, and 9 buffered aqueous solutions under artificial sunlight at 25.0 A? 1.0 A?C. Photolysis in pH 5 buffer is 4.3 times faster than in pH 9 buffer and 1.5 times faster than in pH 7 buffer. In the dark controls, niclosamide degraded only in the pH 5 buffer. After 360 h of continuous irradiation in pH 9 buffer, the chromatographic pattern of the degradates was the same regardless of which ring contained the radiolabel. An HPLC method was developed that confirmed these degradates to be carbon dioxide and two- and four-carbon aliphatic acids formed by cleavage of both aromatic rings. Carbon dioxide was the major degradate, comprising 40% of the initial radioactivity in the 360 h samples from both labels. The other degradates formed were oxalic acid, maleic acid, glyoxylic acid, and glyoxal. In addition, in the chloronitroaniline-labeled irradiated test solution, 2-chloro-4-nitroaniline was observed and identified after 48 h of irradiation but was not detected thereafter. No other aromatic compounds were isolated or observed in either labeled test system.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Aqueous photolysis of niclosamide
Series title:
Journal of Agricultural and Food Chemistry
Volume
52
Issue:
4
Year Published:
2004
Language:
English
Contributing office(s):
Upper Midwest Environmental Sciences Center
Description:
pp. 870-878
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Agricultural and Food Chemistry
First page:
870
Last page:
878