<?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>0379-3982</journal-id>
<journal-title><![CDATA[Revista Tecnología en Marcha]]></journal-title>
<abbrev-journal-title><![CDATA[Tecnología en Marcha]]></abbrev-journal-title>
<issn>0379-3982</issn>
<publisher>
<publisher-name><![CDATA[Instituto Tecnológico de Costa Rica]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0379-39822020000300025</article-id>
<article-id pub-id-type="doi">10.18845/tm.v33i3.4377</article-id>
<title-group>
<article-title xml:lang="es"><![CDATA[Identificación de explosivos Orgánicos en Indicios Post-Explosión mediante GC-MS y GC-NPD]]></article-title>
<article-title xml:lang="en"><![CDATA[Identification of Organic Explosives Clues PostExplosion by GC-MS And GC-NPD Method]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Arce-Rubí]]></surname>
<given-names><![CDATA[Stephanie]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Vargas-Ramírez]]></surname>
<given-names><![CDATA[Steven]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Solís-Montiel]]></surname>
<given-names><![CDATA[Efraín]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Piedra-Marín]]></surname>
<given-names><![CDATA[Gilberto]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Mora-Barrantes]]></surname>
<given-names><![CDATA[Jose Carlos]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Sibaja-Brenes]]></surname>
<given-names><![CDATA[José Pablo]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Borbón-Alpizar]]></surname>
<given-names><![CDATA[Henry]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Organismo de Investigación Judicial Departamento de Ciencias Forenses ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Costa Rica</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,Investigación Judicial Departamento de Ciencias Forenses del Organismo ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Costa Rica</country>
</aff>
<aff id="Af3">
<institution><![CDATA[,Universidad Nacional Escuela de Química ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Costa Rica</country>
</aff>
<aff id="Af4">
<institution><![CDATA[,Universidad Nacional Escuela de Química ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Costa Rica</country>
</aff>
<aff id="Af5">
<institution><![CDATA[,Universidad Nacional Escuela de Química ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Costa Rica</country>
</aff>
<aff id="Af6">
<institution><![CDATA[,Universidad Nacional Escuela de Química ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Costa Rica</country>
</aff>
<aff id="Af7">
<institution><![CDATA[,Universidad Nacional Escuela de Química ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Costa Rica</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>09</month>
<year>2020</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>09</month>
<year>2020</year>
</pub-date>
<volume>33</volume>
<numero>3</numero>
<fpage>25</fpage>
<lpage>44</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.sa.cr/scielo.php?script=sci_arttext&amp;pid=S0379-39822020000300025&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.sa.cr/scielo.php?script=sci_abstract&amp;pid=S0379-39822020000300025&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.sa.cr/scielo.php?script=sci_pdf&amp;pid=S0379-39822020000300025&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="es"><p><![CDATA[Resumen Se implementó y validó un método para la identificación de explosivos por medio de cromatografía de gases acoplada a un detector de espectrometría de masa (GC-MS) y por cromatografía de gases de doble columna acoplada a dos detectores de fósforo-nitrógeno (GC-NPD). El método establecido incluyó el análisis de sustancias explosivas (analitos )de diferente naturaleza química)como TNT, TNB, 2,4-DNT, 2,6-DNT, 2-NT, 3-NT, 4-NT, PETN, NG, RDX y tetril, entre otros. Se evaluó para cada analito el límite de detección, la variabilidad en el tiempo de retención en términos de repetibilidad y precisión intermedia, en ambas técnicas cromatográficas. Utilizando GC-MS las correlaciones encontradas entre los espectros de masas de los patrones y los de los analitos fueron superiores al 90 % para la mayoría de los nitrotoluenos y los estabilizantes de pólvora libre de humos. El análisis por GC-NPD se presentó como método alterno para la identificación de los mismos analitos que se determinan por GC-MS, exceptuando el PETN y el 1,3,5-TNB. Los límites de detección fueron inferiores en uno o dos órdenes de magnitud en relación con los alcanzados por GC-MS y la precisión de los tiempos de retención resultó ser satisfactoria para un análisis cromatográfico. Finalmente, se probó la veracidad y la efectividad de los métodos mediante el análisis de indicios post-explosión obtenidos de las explosiones controladas de seis artefactos explosivos improvisados con cargas explosivas de composición conocida. Los procesos de extracción de las muestras mediante solventes, seguidos por el análisis preliminar de las muestras por TLC y el análisis por GC-MS y GC-NPD permitieron realizar la identificación de al menos un componente explosivo en el 83 % de los casos.]]></p></abstract>
<abstract abstract-type="short" xml:lang="en"><p><![CDATA[Abstract Methods for the identification of explosives by means of Gas Chromatography Mass Spectrometry (GC-MS) and Gas Chromatography with Nitrogen Phosphorus Detectors (GC-NPD) were implemented and validated. The methods established included the analysis of the following explosive substances: TNT, TNB, 2,4-DNT, 2,6-DNT, 2-NT, 3-NT, 4-NT, PETN, NG, RDX and tetril. For each analyte, the detection limit, the variability in retention time for each analyte, in terms of repeatability and intermediate precision were evaluated by using both chromatography techniques. By means of GC-MS the correlations found between the mass spectrum of the standards and those of the analytes went over 90% for the majority of the nitrotoluenes and for some stabilizers of smoke-free gunpowder. The GC-NPD analysis is an alternative method for the identification of the same analytes done by using GC-MS, with the only exceptions of PETN and 1,3,5 -TBN. The detection limits of these two compounds were inferior with respect to the ones reached by GC-MS. Finally, veracity and effectiveness for both methods were proven by analysing post-explosion samples of six explosive materials. All the explosion events were developed under controlled situations. The samples were extracted through organic solvents; then they were analysed by TLC, GC-MS and GC-NDP. This methods allowed the identification at least of one explosive component in the majority of the samples (83%).]]></p></abstract>
<kwd-group>
<kwd lng="es"><![CDATA[Explosivos]]></kwd>
<kwd lng="es"><![CDATA[detonaciones]]></kwd>
<kwd lng="es"><![CDATA[cromatografía]]></kwd>
<kwd lng="es"><![CDATA[componentes explosivos]]></kwd>
<kwd lng="es"><![CDATA[validación]]></kwd>
<kwd lng="en"><![CDATA[Explosives]]></kwd>
<kwd lng="en"><![CDATA[detonations]]></kwd>
<kwd lng="en"><![CDATA[chromatography]]></kwd>
<kwd lng="en"><![CDATA[explosive components]]></kwd>
<kwd lng="en"><![CDATA[validation]]></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[Akhavan]]></surname>
<given-names><![CDATA[J]]></given-names>
</name>
</person-group>
<source><![CDATA[The Chemistry of Explosives, 2nd ed. London: RSC]]></source>
<year>2004</year>
<page-range>21-7</page-range></nlm-citation>
</ref>
<ref id="B2">
<label>(2)</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Meyer]]></surname>
<given-names><![CDATA[R]]></given-names>
</name>
<name>
<surname><![CDATA[Köhler]]></surname>
<given-names><![CDATA[J]]></given-names>
</name>
<name>
<surname><![CDATA[Homburg]]></surname>
<given-names><![CDATA[A]]></given-names>
</name>
</person-group>
<source><![CDATA[Explosives]]></source>
<year>2007</year>
<edition>6th</edition>
<page-range>131-2</page-range></nlm-citation>
</ref>
<ref id="B3">
<label>(3)</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Beveridge]]></surname>
<given-names><![CDATA[A]]></given-names>
</name>
</person-group>
<source><![CDATA[Forensic Investigation of Explosions]]></source>
<year>2011</year>
<edition>2nd</edition>
<page-range>4-23</page-range></nlm-citation>
</ref>
<ref id="B4">
<label>(4)</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Venugopalan]]></surname>
<given-names><![CDATA[S]]></given-names>
</name>
</person-group>
<source><![CDATA[Demystifying explosives: Concepts in high energy materials.]]></source>
<year>2014</year>
<page-range>1-14</page-range><publisher-loc><![CDATA[Russland ]]></publisher-loc>
<publisher-name><![CDATA[Elsevier]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B5">
<label>(5)</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Urbanski]]></surname>
<given-names><![CDATA[T]]></given-names>
</name>
</person-group>
<source><![CDATA[Chemistry and technology of explosives]]></source>
<year>1964</year>
<volume>1</volume>
<page-range>1-268-285</page-range><publisher-loc><![CDATA[Poland ]]></publisher-loc>
<publisher-name><![CDATA[Pergamon Press]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B6">
<label>(6)</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Warey]]></surname>
<given-names><![CDATA[P]]></given-names>
</name>
</person-group>
<source><![CDATA[New research on hazardous materials]]></source>
<year>2007</year>
<page-range>371-3</page-range><publisher-loc><![CDATA[New York ]]></publisher-loc>
<publisher-name><![CDATA[Nova Science Publishers]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B7">
<label>(7)</label><nlm-citation citation-type="">
<article-title xml:lang=""><![CDATA[&#8220;Explosives analysis in the environment,&#8221;]]></article-title>
<source><![CDATA[Encyclopedia of Analytical Chemistry,]]></source>
<year>2006</year>
<volume>3</volume>
<page-range>2402-3</page-range></nlm-citation>
</ref>
<ref id="B8">
<label>(8)</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Peterson]]></surname>
<given-names><![CDATA[M]]></given-names>
</name>
</person-group>
<source><![CDATA[&#8220;TNT and 4-amino-2,6-dinitrotoluene influence on germination and early seedling development of tall fescue&#8221;]]></source>
<year>1995</year>
<page-range>57-8</page-range></nlm-citation>
</ref>
<ref id="B9">
<label>(9)</label><nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Hewitt]]></surname>
<given-names><![CDATA[A]]></given-names>
</name>
<name>
<surname><![CDATA[Jenkins]]></surname>
<given-names><![CDATA[T]]></given-names>
</name>
<name>
<surname><![CDATA[Ranney]]></surname>
<given-names><![CDATA[T]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[On-site gas chromatographic determination of explosives in soils]]></article-title>
<source><![CDATA[in Field analytical chemistry and technology]]></source>
<year>2001</year>
<volume>5</volume>
<page-range>228-9</page-range></nlm-citation>
</ref>
<ref id="B10">
<label>(10)</label><nlm-citation citation-type="">
<collab>US Environmental Protection Agency</collab>
<source><![CDATA[&#8220;Method 8515: Colorimetric screening method for trinitrotoluene (TNT) in soil.&#8221;]]></source>
<year>2015</year>
</nlm-citation>
</ref>
<ref id="B11">
<label>(11)</label><nlm-citation citation-type="">
<collab>US Environmental Protection Agency</collab>
<source><![CDATA[&#8220;Method 8510: Colorimetric screening procedure for RDX and HMX in soil.&#8221;]]></source>
<year>2015</year>
</nlm-citation>
</ref>
<ref id="B12">
<label>(12)</label><nlm-citation citation-type="">
<collab>US Environmental Protection Agency</collab>
<source><![CDATA[&#8220;Method 4050: TNT explosives in soil by inmunoassay.&#8221;]]></source>
<year>2015</year>
</nlm-citation>
</ref>
<ref id="B13">
<label>(13)</label><nlm-citation citation-type="">
<collab>US Environmental Protection Agency</collab>
<source><![CDATA[Method 4051: Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in soil by inmunoassay.&#8221;]]></source>
<year>2015</year>
</nlm-citation>
</ref>
<ref id="B14">
<label>(14)</label><nlm-citation citation-type="">
<collab>US Environmental Protection Agency</collab>
<source><![CDATA[&#8220;Method 8330A: Nitroaromatics and nitramines by high performance liquid chromatography (HPLC).&#8221;]]></source>
<year>2015</year>
<month>)</month>
</nlm-citation>
</ref>
<ref id="B15">
<label>(15)</label><nlm-citation citation-type="">
<collab>US Environmental Protection Agency</collab>
<source><![CDATA[Method 8330B: Nitroaromatics, nitramines, and nitrate esters by high performance liquid chromatography (HPLC).&#8221;]]></source>
<year>2015</year>
</nlm-citation>
</ref>
<ref id="B16">
<label>(16)</label><nlm-citation citation-type="">
<collab>US Environmental Protection Agency</collab>
<source><![CDATA[&#8220;Method 8095: Explosives by Gas Chromatography.&#8221;]]></source>
<year>2015</year>
</nlm-citation>
</ref>
<ref id="B17">
<label>(17)</label><nlm-citation citation-type="">
<collab>US Environmental Protection Agency</collab>
<source><![CDATA[&#8220;Method 529: Determination of explosives and related compounds in drinking water y solid phase extraction and capillary column gas chromatography/mass spectrometry (GC/ MS).&#8221;]]></source>
<year>2015</year>
</nlm-citation>
</ref>
<ref id="B18">
<label>(18)</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Schade]]></surname>
<given-names><![CDATA[W]]></given-names>
</name>
<name>
<surname><![CDATA[Orghici]]></surname>
<given-names><![CDATA[R]]></given-names>
</name>
<name>
<surname><![CDATA[Mordmüller]]></surname>
<given-names><![CDATA[M]]></given-names>
</name>
<name>
<surname><![CDATA[Willer]]></surname>
<given-names><![CDATA[U]]></given-names>
</name>
</person-group>
<source><![CDATA[Detection of explosives]]></source>
<year>2012</year>
<page-range>195-6</page-range><publisher-loc><![CDATA[U.S.A. ]]></publisher-loc>
<publisher-name><![CDATA[Wiley-VCH Verlag GmbH &amp; Co. KGaA]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B19">
<label>(19)</label><nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Varga]]></surname>
<given-names><![CDATA[R]]></given-names>
</name>
<name>
<surname><![CDATA[Ulbrich]]></surname>
<given-names><![CDATA[P]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Some experience with trace analysis of post-explosion residues.]]></article-title>
<source><![CDATA[Arms Technology]]></source>
<year>2004</year>
<numero>3</numero>
<issue>3</issue>
<page-range>634</page-range></nlm-citation>
</ref>
<ref id="B20">
<label>(20)</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Byall]]></surname>
<given-names><![CDATA[E. B.]]></given-names>
</name>
</person-group>
<source><![CDATA[Detection and characterization of explosives and explosive residue: A review,&#8221; in 13th INTERPOL Forensic Science Symposium]]></source>
<year>2001</year>
<page-range>100-106.</page-range></nlm-citation>
</ref>
<ref id="B21">
<label>(21)</label><nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Royds]]></surname>
<given-names><![CDATA[D]]></given-names>
</name>
<name>
<surname><![CDATA[Lewis]]></surname>
<given-names><![CDATA[S]]></given-names>
</name>
<name>
<surname><![CDATA[Taylor]]></surname>
<given-names><![CDATA[A]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[A case study in forensic chemistry: The Bali bombings]]></article-title>
<source><![CDATA[Talanta]]></source>
<year>2005</year>
<numero>67</numero>
<issue>67</issue>
<page-range>262-8</page-range></nlm-citation>
</ref>
<ref id="B22">
<label>(22)</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Garrido]]></surname>
<given-names><![CDATA[R]]></given-names>
</name>
</person-group>
<source><![CDATA[Uso de la espectrometría de movilidad iónica como técnica de vanguardia en los laboratorios analíticos de rutina&#8221;]]></source>
<year>2012</year>
<page-range>25-33</page-range><publisher-name><![CDATA[Servicio de Publicaciones de la Universidad de Córdoba]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B23">
<label>(23)</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Rhykerd]]></surname>
<given-names><![CDATA[C. L.]]></given-names>
</name>
<name>
<surname><![CDATA[Hannum]]></surname>
<given-names><![CDATA[D. W.]]></given-names>
</name>
<name>
<surname><![CDATA[Murray]]></surname>
<given-names><![CDATA[D. W.]]></given-names>
</name>
<name>
<surname><![CDATA[Parmeter]]></surname>
<given-names><![CDATA[J. E.]]></given-names>
</name>
</person-group>
<source><![CDATA[&#8220;Guide for the selection of commercial explosives detection systems for Law enforcement applications&#8221;]]></source>
<year>1999</year>
<page-range>10-20</page-range></nlm-citation>
</ref>
<ref id="B24">
<label>(24)</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Miller]]></surname>
<given-names><![CDATA[J]]></given-names>
</name>
</person-group>
<source><![CDATA[Estadística y quimiometría para Química Analítica]]></source>
<year>2002</year>
<edition>4</edition>
<page-range>125-6</page-range></nlm-citation>
</ref>
<ref id="B25">
<label>(25)</label><nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Skoog]]></surname>
<given-names><![CDATA[D]]></given-names>
</name>
<name>
<surname><![CDATA[Holler]]></surname>
<given-names><![CDATA[F]]></given-names>
</name>
<name>
<surname><![CDATA[Nieman]]></surname>
<given-names><![CDATA[A]]></given-names>
</name>
</person-group>
<source><![CDATA[Principios de análisis instrumental]]></source>
<year>2003</year>
<edition>5</edition>
<page-range>103-4</page-range></nlm-citation>
</ref>
<ref id="B26">
<label>(26)</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Thurman]]></surname>
<given-names><![CDATA[J]]></given-names>
</name>
</person-group>
<source><![CDATA[Practical Bomb Scene Investigation]]></source>
<year>2006</year>
<page-range>187-90</page-range><publisher-loc><![CDATA[Canada ]]></publisher-loc>
<publisher-name><![CDATA[CRC Press]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B27">
<label>(27)</label><nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Underhill]]></surname>
<given-names><![CDATA[P. R.]]></given-names>
</name>
<name>
<surname><![CDATA[Bardon]]></surname>
<given-names><![CDATA[M. F.]]></given-names>
</name>
</person-group>
<source><![CDATA[&#8220;Modelling of thermal ignition of RDX/HTPB based PBXS&#8221;]]></source>
<year>1996</year>
<page-range>50-7</page-range><publisher-name><![CDATA[Canada]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B28">
<label>(28)</label><nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Borusiewicz]]></surname>
<given-names><![CDATA[R]]></given-names>
</name>
<name>
<surname><![CDATA[Zadora]]></surname>
<given-names><![CDATA[G]]></given-names>
</name>
<name>
<surname><![CDATA[Zieba-Palus]]></surname>
<given-names><![CDATA[J]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Chemical analysis of post explosion samples obtained as a result of model field experiments]]></article-title>
<source><![CDATA[Talanta]]></source>
<year>2013</year>
<numero>116</numero>
<issue>116</issue>
<page-range>630-6</page-range></nlm-citation>
</ref>
<ref id="B29">
<label>(29)</label><nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Stashenko]]></surname>
<given-names><![CDATA[E]]></given-names>
</name>
<name>
<surname><![CDATA[Martínez]]></surname>
<given-names><![CDATA[J]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[GC y GC-MS: configuración del equipo versus aplicaciones]]></article-title>
<source><![CDATA[Scientia Chromatographica]]></source>
<year>2010</year>
<page-range>49-50</page-range></nlm-citation>
</ref>
<ref id="B30">
<label>(30)</label><nlm-citation citation-type="">
<collab>Wada Laboratory Committee</collab>
<source><![CDATA[&#8220;Identification criteria for qualitative assays incorporating column chromatography and mass spectrometry&#8221;]]></source>
<year>2010</year>
</nlm-citation>
</ref>
</ref-list>
</back>
</article>
