<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>0188-4999</journal-id>
<journal-title><![CDATA[Revista internacional de contaminación ambiental]]></journal-title>
<abbrev-journal-title><![CDATA[Rev. Int. Contam. Ambient]]></abbrev-journal-title>
<issn>0188-4999</issn>
<publisher>
<publisher-name><![CDATA[Universidad Nacional Autónoma de México, Instituto de Ciencias de la Atmósfera y Cambio Climático]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0188-49992006000100021</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[EFFECT OF ZN(II) ON ACID HYDROLYSIS OF METHYLPARATHION]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Manzanilla-Cano]]></surname>
<given-names><![CDATA[José A.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Barceló-Quintal]]></surname>
<given-names><![CDATA[Manuel H.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Rendón-Osorio]]></surname>
<given-names><![CDATA[Reyna B.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Flores-Rodríguez]]></surname>
<given-names><![CDATA[Julio]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Universidad de Yucatán Facultad de Química Departamento de Química Analítica]]></institution>
<addr-line><![CDATA[Mérida Yucatán]]></addr-line>
<country>México</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,UAM Departamento de Ciencias Básicas ]]></institution>
<addr-line><![CDATA[D.F. ]]></addr-line>
<country>México</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>03</month>
<year>2006</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>03</month>
<year>2006</year>
</pub-date>
<volume>22</volume>
<numero>1</numero>
<fpage>21</fpage>
<lpage>26</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0188-49992006000100021&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0188-49992006000100021&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0188-49992006000100021&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[ABSTRACT Methylparathion (O,O,-dimethyl O-4 nitrophenylphosphorotioate) kinetic transformation in presence of Zn(II) was studied at pH range from 2 to 7. Between pH 2-5 methylparathion degraded, but at pH 6 and 7 Zn(II) precipitated and the pesticide hydrolysis did not occur. The reaction was first order and the rate constant values were 3.38 x 10-2 h-1 (pH 2), 7.69 x 10-3 h-1 (pH 3), 1.31 x 10-2 h-1 (pH 4) and 1.02 x 10-2 h-1 (pH 5). Paranitrophenol appeared as the only electroactive product at all pH values. It is proposed that the main degradation pathway for methylparathion in acid medium was a hydrolysis reaction of the pesticide catalyzed by Zn(II), via an electrophilic mechanism.]]></p></abstract>
<abstract abstract-type="short" xml:lang="es"><p><![CDATA[RESUMEN Se estudió la cinética de transformación del metilparatión (O,O,-dimetil O-4 nitrofenilfosforotioato) en presencia de Zn(II) en el intervalo de pH de 2 a 7. Se observó la degradación del metilparatión en el intervalo de pH de 2 a 5, sin embargo a pH6 y 7 el Zn(II) precipitó y no ocurrió la hidrólisis del plaguicida. La reacción fue de primer orden y los valores de las constantes de velocidad fueron 3.38 x 10-2 h-1, 7.69 x 10-3 h-1, 1.31 x 10-2 h-1 y 1.02 x 10-2 h-1, a los valores de pH de 2, 3, 4 y 5, respectivamente. El paranitrofenol fue el único producto electroactivo observado a todos los valores de pH. Se propone que la ruta de degradación principal del metilparatión en medio ácido, fue una reacción de hidrólisis del plaguicida, catalizada por el Zn(II), vía un mecanismo electrofílico.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[methylparathion]]></kwd>
<kwd lng="en"><![CDATA[Zn(II)]]></kwd>
<kwd lng="en"><![CDATA[hydrolysis]]></kwd>
<kwd lng="en"><![CDATA[polarography]]></kwd>
<kwd lng="en"><![CDATA[paranitrophenol]]></kwd>
<kwd lng="es"><![CDATA[metilparatión]]></kwd>
<kwd lng="es"><![CDATA[Zn(II)]]></kwd>
<kwd lng="es"><![CDATA[hidrólisis]]></kwd>
<kwd lng="es"><![CDATA[polarografía]]></kwd>
<kwd lng="es"><![CDATA[paranitrofenol]]></kwd>
</kwd-group>
</article-meta>
</front><back>
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