Fate And Transformation Of Quinoxaline
N’N’-dioxide Antibacterial Agents
During Chlorination
Author(s)
A. Shah, J.-H. Kim & C.-H. Huang
Abstract
Quinoxaline N’N’-dioxides are an important group of veterinary antibiotics
whose fate in the environment can be greatly altered by potential reactions
during chlorination of wastewater and drinking waters. Their presence is of
particular concern due to their potential mutagenic, carcinogenic, and
embryotoxic effects. Experiments show that quinoxaline N’N’-dioxides such as
carbadox and its metabolite, desoxycarbadox, are highly susceptible to oxidation
with chlorine and chloramines, in which the reaction rate of carbadox with free
chlorine is extremely rapid and highly pH-dependent. No reactions were found
to occur for a series of structurally-related compounds that resemble portions of
this parent compound, which suggest that carbadox’s side chain, rather than the
aromatic N’N’-dioxide moiety, holds especially high reactivity to chlorine and
chloramines oxidants. Several dominant oxidation by-products of carbadox and
desoxycarbadox have been preliminarily identified. Further studies will
elucidate the transformation pathways and evaluate reaction kinetics in real water
matrices.
Keywords: Quinoxaline N’N’-dioxides, carbadox, desoxycarbadox, olaquindox,
veterinary antibiotics, oxidation, chlorine disinfection.
1 Introduction
Quinoxaline N’N’-dioxides (QNOs) are antibacterial agents primarily used in
animal husbandry to promote growth and prevent dysentery and bacterial
enterities in young swine. Two compounds that are most widely used from this
class are carbadox (CDX) (methyl-3-(2-quinoxalinylmethylene) carbazate N,N’-
dioxide) and olaquindox (ODX) (2-methyl-3-(N-(2-hydroxyethyl)carbamoyl)-
Keywords
Quinoxaline N’N’-dioxides, carbadox, desoxycarbadox, olaquindox,
veterinary antibiotics, oxidation, chlorine disinfection.
Related Book
Other papers in this volume
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