<?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>1870-249X</journal-id>
<journal-title><![CDATA[Journal of the Mexican Chemical Society]]></journal-title>
<abbrev-journal-title><![CDATA[J. Mex. Chem. Soc]]></abbrev-journal-title>
<issn>1870-249X</issn>
<publisher>
<publisher-name><![CDATA[Sociedad Química de México A.C.]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S1870-249X2025000100008</article-id>
<article-id pub-id-type="doi">10.29356/jmcs.v69i1.2293</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[Tetracycline Speciation Study in Aqueous Medium]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[González-Garrido]]></surname>
<given-names><![CDATA[Luis Diego]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Guzmán-Hernández]]></surname>
<given-names><![CDATA[Dafne Sarahia]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Rojas-Hernández]]></surname>
<given-names><![CDATA[Alberto]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Rodríguez-Barrientos]]></surname>
<given-names><![CDATA[Damaris]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Juárez-Gómez]]></surname>
<given-names><![CDATA[Jorge]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Ramírez-Silva]]></surname>
<given-names><![CDATA[María Teresa]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Universidad Autónoma Metropolitana Departamento de Química ]]></institution>
<addr-line><![CDATA[Iztapalapa Ciudad de México]]></addr-line>
<country>Mexico</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,Universidad Autónoma Metropolitana Departamento de Química ]]></institution>
<addr-line><![CDATA[Iztapalapa Ciudad de México]]></addr-line>
<country>Mexico</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>03</month>
<year>2025</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>03</month>
<year>2025</year>
</pub-date>
<volume>69</volume>
<numero>1</numero>
<fpage>78</fpage>
<lpage>87</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S1870-249X2025000100008&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S1870-249X2025000100008&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S1870-249X2025000100008&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[Abstract. Tetracycline is a broad-spectrum antibiotic considered an emerging contaminant with major effects on human health and the ecosystems. Using the techniques of UV absorption spectroscopy and capillary zone electrophoresis, the characterization of tetracycline in aqueous medium is presented. Likewise, four acidity constants were determined:    p K a  1 =   p K    T c H  3    T c H  4  + ,  =  ( 3.277  ±  0.067 ),      p K a  2 =  p K    T c H  2  -    T c H  3  =  ( 7.397  ±  0.055 ),    p K a  3 =    p K    T c H  2 -    T c H  2  - =  ( 9.349  ±  0.039 ) and      p K a  4 = p K    T c  3 -    T c H  2 - =  ( 11.278  ±  0.024 ). Finally, capillary zone electrophoresis corroborates the predominance of five tetracycline species (TcH4 +, TcH3, TcH2 -, TcH2- and Tc3-) and presents a proposal for the deprotonation mechanism for tetracycline in aqueous medium.]]></p></abstract>
<abstract abstract-type="short" xml:lang="es"><p><![CDATA[Resumen. La tetraciclina es un antibiótico de amplio espectro, considerado como contaminante emergente con grandes afectaciones a la salud humana y el ecosistema. Mediante las técnicas de espectroscopía de absorción de UV y electroforesis capilar de zona se presenta la caracterización de la tetraciclina en medio acuoso. Así mismo se determinaron cuatro constantes de acidez:    p K a  1 =   p K    T c H  3    T c H  4  + ,  =  ( 3.277  ±  0.067 ),      p K a  2 =  p K    T c H  2  -    T c H  3  =  ( 7.397  ±  0.055 ),    p K a  3 =    p K    T c H  2 -    T c H  2  - =  ( 9.349  ±  0.039 ) y      p K a  4 = p K    T c  3 -    T c H  2 - =  ( 11.278  ±  0.024 ). Finalmente, a partir de electroforesis capilar de zona se corrobora el predominio de cinco especies de tetraciclina (TcH4 +, TcH3, TcH2 -, TcH2- y Tc3-) y se presenta una propuesta del mecanismo de desprotonación para tetraciclina en medio acuoso.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[Tetracycline]]></kwd>
<kwd lng="en"><![CDATA[stability]]></kwd>
<kwd lng="en"><![CDATA[acidity constants]]></kwd>
<kwd lng="en"><![CDATA[speciation]]></kwd>
<kwd lng="en"><![CDATA[capillary zone electrophoresis]]></kwd>
<kwd lng="es"><![CDATA[Tetraciclina]]></kwd>
<kwd lng="es"><![CDATA[estabilidad]]></kwd>
<kwd lng="es"><![CDATA[constantes de acidez]]></kwd>
<kwd lng="es"><![CDATA[especiación]]></kwd>
<kwd lng="es"><![CDATA[electroforesis capilar de zona]]></kwd>
</kwd-group>
</article-meta>
</front><back>
<ref-list>
<ref id="B1">
<label>1.</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Liang]]></surname>
<given-names><![CDATA[Y.]]></given-names>
</name>
<name>
<surname><![CDATA[Denton]]></surname>
<given-names><![CDATA[M. B.]]></given-names>
</name>
<name>
<surname><![CDATA[Bates]]></surname>
<given-names><![CDATA[R. B.]]></given-names>
</name>
</person-group>
<source><![CDATA[J. Chromatogr. A]]></source>
<year>1998</year>
<numero>827</numero>
<issue>827</issue>
<page-range>45-55</page-range></nlm-citation>
</ref>
<ref id="B2">
<label>2.</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Yang]]></surname>
<given-names><![CDATA[B.]]></given-names>
</name>
<name>
<surname><![CDATA[Cheng]]></surname>
<given-names><![CDATA[X.]]></given-names>
</name>
<name>
<surname><![CDATA[Zhang]]></surname>
<given-names><![CDATA[Y.]]></given-names>
</name>
<name>
<surname><![CDATA[Li]]></surname>
<given-names><![CDATA[W.]]></given-names>
</name>
<name>
<surname><![CDATA[Wang]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
<name>
<surname><![CDATA[Guo]]></surname>
<given-names><![CDATA[H.]]></given-names>
</name>
</person-group>
<source><![CDATA[Enviro. Sci. Ecotechnol]]></source>
<year>2021</year>
<numero>8</numero>
<issue>8</issue>
</nlm-citation>
</ref>
<ref id="B3">
<label>3.</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Wu]]></surname>
<given-names><![CDATA[Y.]]></given-names>
</name>
<name>
<surname><![CDATA[Fassihi]]></surname>
<given-names><![CDATA[R.]]></given-names>
</name>
</person-group>
<source><![CDATA[Int. J. Pharm]]></source>
<year>2005</year>
<volume>290</volume>
<numero>1</numero>
<issue>1</issue>
<page-range>1-13</page-range></nlm-citation>
</ref>
<ref id="B4">
<label>4.</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Amangelsin]]></surname>
<given-names><![CDATA[Y.]]></given-names>
</name>
<name>
<surname><![CDATA[Semenova]]></surname>
<given-names><![CDATA[Y.]]></given-names>
</name>
<name>
<surname><![CDATA[Dadar]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
<name>
<surname><![CDATA[Aljofan]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
<name>
<surname><![CDATA[Bjøklund]]></surname>
<given-names><![CDATA[G.]]></given-names>
</name>
</person-group>
<source><![CDATA[Antibiotics]]></source>
<year>2023</year>
<volume>12</volume>
<numero>440</numero>
<issue>440</issue>
</nlm-citation>
</ref>
<ref id="B5">
<label>5.</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Daghrir]]></surname>
<given-names><![CDATA[R.]]></given-names>
</name>
<name>
<surname><![CDATA[Drogui]]></surname>
<given-names><![CDATA[P.]]></given-names>
</name>
</person-group>
<source><![CDATA[Environ. Chem. Lett]]></source>
<year>2013</year>
<numero>11</numero>
<issue>11</issue>
<page-range>209-27</page-range></nlm-citation>
</ref>
<ref id="B6">
<label>6.</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Schmitt]]></surname>
<given-names><![CDATA[M. O.]]></given-names>
</name>
<name>
<surname><![CDATA[Siegfried]]></surname>
<given-names><![CDATA[S.]]></given-names>
</name>
<name>
<surname><![CDATA[Nelson]]></surname>
<given-names><![CDATA[M. L.]]></given-names>
</name>
</person-group>
<source><![CDATA[Z. fur Phys. Chem]]></source>
<year>2007</year>
<numero>221</numero>
<issue>221</issue>
<page-range>235-71</page-range></nlm-citation>
</ref>
<ref id="B7">
<label>7.</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Tavares]]></surname>
<given-names><![CDATA[M. F. M.]]></given-names>
</name>
<name>
<surname><![CDATA[McGuffin]]></surname>
<given-names><![CDATA[V. L.]]></given-names>
</name>
</person-group>
<source><![CDATA[J. Chromatogr. A]]></source>
<year>1994</year>
<numero>686</numero>
<issue>686</issue>
<page-range>129-42</page-range></nlm-citation>
</ref>
<ref id="B8">
<label>8.</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Duarte]]></surname>
<given-names><![CDATA[H. A.]]></given-names>
</name>
<name>
<surname><![CDATA[Carvalho]]></surname>
<given-names><![CDATA[S.]]></given-names>
</name>
<name>
<surname><![CDATA[Paniago]]></surname>
<given-names><![CDATA[E. B.]]></given-names>
</name>
<name>
<surname><![CDATA[Simas]]></surname>
<given-names><![CDATA[A. M.]]></given-names>
</name>
</person-group>
<source><![CDATA[J. Pharm. Sci]]></source>
<year>1999</year>
<numero>88</numero>
<issue>88</issue>
<page-range>111-20</page-range></nlm-citation>
</ref>
<ref id="B9">
<label>9.</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Townshend]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<name>
<surname><![CDATA[Burns]]></surname>
<given-names><![CDATA[D. T.]]></given-names>
</name>
<name>
<surname><![CDATA[Newman]]></surname>
<given-names><![CDATA[E. J.]]></given-names>
</name>
<name>
<surname><![CDATA[Guilbault]]></surname>
<given-names><![CDATA[G.]]></given-names>
</name>
<name>
<surname><![CDATA[Marczenko]]></surname>
<given-names><![CDATA[Z.]]></given-names>
</name>
<name>
<surname><![CDATA[Onishi]]></surname>
<given-names><![CDATA[H.]]></given-names>
</name>
</person-group>
<source><![CDATA[Dictionary of Analytical Reagents Chapman &amp; Hall chemical database]]></source>
<year>1993</year>
<publisher-loc><![CDATA[CRC ]]></publisher-loc>
<publisher-name><![CDATA[Chapman and Hall]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B10">
<label>10.</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Leggett]]></surname>
<given-names><![CDATA[D. J.]]></given-names>
</name>
</person-group>
<source><![CDATA[Computational Methods for the Determination of Formation Constants. Modern Inorganic Chemistry]]></source>
<year>1985</year>
<publisher-loc><![CDATA[Boston ]]></publisher-loc>
<publisher-name><![CDATA[Springer]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B11">
<label>11.</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Rivas-Sanchez]]></surname>
<given-names><![CDATA[A.K.]]></given-names>
</name>
<name>
<surname><![CDATA[Guzmán-Hernández]]></surname>
<given-names><![CDATA[D.S.]]></given-names>
</name>
<name>
<surname><![CDATA[Ramírez-Silva]]></surname>
<given-names><![CDATA[M.T.]]></given-names>
</name>
<name>
<surname><![CDATA[Romero-Romo]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
<name>
<surname><![CDATA[Palomar-Pardavé]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
</person-group>
<source><![CDATA[Dyes Pigm]]></source>
<year>2021</year>
<numero>184</numero>
<issue>184</issue>
</nlm-citation>
</ref>
<ref id="B12">
<label>12.</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Guzmán-Hernández]]></surname>
<given-names><![CDATA[D.S.]]></given-names>
</name>
<name>
<surname><![CDATA[Palomar-Pardavé]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
<name>
<surname><![CDATA[Sánchez-Pérez]]></surname>
<given-names><![CDATA[F.]]></given-names>
</name>
<name>
<surname><![CDATA[Juárez-Gómez]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
<name>
<surname><![CDATA[Corona-Avendaño]]></surname>
<given-names><![CDATA[S.]]></given-names>
</name>
<name>
<surname><![CDATA[Ramírez-Silva]]></surname>
<given-names><![CDATA[M.T.]]></given-names>
</name>
<name>
<surname><![CDATA[Romero-Romo]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
</person-group>
<source><![CDATA[Spectrochim. Acta A Mol. Biomol. Spectrosc]]></source>
<year>2020</year>
<numero>228</numero>
<issue>228</issue>
</nlm-citation>
</ref>
<ref id="B13">
<label>13.</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Rojas-Hernández]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<name>
<surname><![CDATA[Rodríguez-Laguna]]></surname>
<given-names><![CDATA[N.]]></given-names>
</name>
<name>
<surname><![CDATA[Ramírez-Silva]]></surname>
<given-names><![CDATA[M. T.]]></given-names>
</name>
<name>
<surname><![CDATA[Moya-Hernández]]></surname>
<given-names><![CDATA[R.]]></given-names>
</name>
</person-group>
<source><![CDATA[InTech]]></source>
<year>2012</year>
</nlm-citation>
</ref>
<ref id="B14">
<label>14.</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Rodríguez-Barrientos]]></surname>
<given-names><![CDATA[D.]]></given-names>
</name>
<name>
<surname><![CDATA[Rojas-Hernández]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<name>
<surname><![CDATA[Gutiérrez]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<name>
<surname><![CDATA[Moya-Hernández]]></surname>
<given-names><![CDATA[R.]]></given-names>
</name>
<name>
<surname><![CDATA[Gómez-Balderas]]></surname>
<given-names><![CDATA[R.]]></given-names>
</name>
<name>
<surname><![CDATA[Ramírez-Silva]]></surname>
<given-names><![CDATA[M. T.]]></given-names>
</name>
</person-group>
<source><![CDATA[Talanta]]></source>
<year>2009</year>
<numero>80</numero>
<issue>80</issue>
<page-range>754-62</page-range></nlm-citation>
</ref>
<ref id="B15">
<label>15.</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Nytrrová]]></surname>
<given-names><![CDATA[L.]]></given-names>
</name>
<name>
<surname><![CDATA[Odehnalová]]></surname>
<given-names><![CDATA[K.]]></given-names>
</name>
<name>
<surname><![CDATA[Pazourek]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
</person-group>
<source><![CDATA[ACS Omega]]></source>
<year>2022</year>
<numero>7</numero>
<issue>7</issue>
<page-range>1477-82</page-range></nlm-citation>
</ref>
<ref id="B16">
<label>16.</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Rojas-Hernández]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<name>
<surname><![CDATA[Ramírez]]></surname>
<given-names><![CDATA[M.T.]]></given-names>
</name>
<name>
<surname><![CDATA[González]]></surname>
<given-names><![CDATA[I.]]></given-names>
</name>
<name>
<surname><![CDATA[Ibáñez]]></surname>
<given-names><![CDATA[J. G.]]></given-names>
</name>
</person-group>
<source><![CDATA[Anal. Chim. Acta]]></source>
<year>1992</year>
<numero>259</numero>
<issue>259</issue>
<page-range>95-104</page-range></nlm-citation>
</ref>
<ref id="B17">
<label>17.</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Rojas-Hernández]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<name>
<surname><![CDATA[Ramírez]]></surname>
<given-names><![CDATA[M. T.]]></given-names>
</name>
<name>
<surname><![CDATA[González]]></surname>
<given-names><![CDATA[I.]]></given-names>
</name>
<name>
<surname><![CDATA[Ibanez]]></surname>
<given-names><![CDATA[J. G.]]></given-names>
</name>
</person-group>
<source><![CDATA[J. Chem. Educ]]></source>
<year>1995</year>
<numero>72</numero>
<issue>72</issue>
<page-range>1099-105</page-range></nlm-citation>
</ref>
</ref-list>
</back>
</article>
