{"id":2962,"date":"2016-05-18T22:49:14","date_gmt":"2016-05-18T21:49:14","guid":{"rendered":"http:\/\/agora.xtec.cat\/ies-merce-rodoreda\/?p=2962"},"modified":"2016-05-22T21:31:21","modified_gmt":"2016-05-22T20:31:21","slug":"determinacion-de-nitritiso-en-aguas-por-espectroscopia-de-abosrcion-molecular-uv-vis","status":"publish","type":"post","link":"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/modul-a\/determinacion-de-nitritiso-en-aguas-por-espectroscopia-de-abosrcion-molecular-uv-vis\/","title":{"rendered":"Determinaci\u00f3n de nitritos en aguas por espectroscop\u00eda de absorci\u00f3n molecular UV-Vis"},"content":{"rendered":"<p><img loading=\"lazy\" decoding=\"async\" class=\"  wp-image-2966 aligncenter\" src=\"http:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-content\/uploads\/usu644\/2016\/05\/esper.jpg\" alt=\"esper\" width=\"426\" height=\"319\" srcset=\"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-content\/uploads\/usu644\/2016\/05\/esper.jpg 259w, https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-content\/uploads\/usu644\/2016\/05\/esper-200x150.jpg 200w\" sizes=\"auto, (max-width: 426px) 100vw, 426px\" \/><\/p>\n<p>El nitr\u00f3geno es un elemento muy abundante en la atm\u00f3sfera donde alcanza casi un 80% en volumen. En los seres vivos, su ubicaci\u00f3n principal se encuentra en las prote\u00ednas donde puede alcanzar hasta el 20% en peso de las mismas. Los principales compuestos de nitr\u00f3geno presentes en la naturaleza, adem\u00e1s del nitr\u00f3geno molecular atmosf\u00e9rico y del nitr\u00f3geno en materias org\u00e1nicas, son nitratos, nitritos y amonio. Desde el punto de vista de estabilidad, el nitrito es el m\u00e1s inestable.<!--more--><\/p>\n<p>La presencia de nitritos en aguas es un indicador de calidad de las mismas y por este motivo es necesario poder cuantificarlo. Para ello existen una serie de t\u00e9cnicas de an\u00e1lisis. A continuaci\u00f3n se exponen el m\u00e1s com\u00fan es el m\u00e9todo colorim\u00e9trico.<\/p>\n<p><strong>Fuente 1:<\/strong> Determinaci\u00f3n de los nitritos en muestras de agua<\/p>\n<p>El m\u00e9todo colorim\u00e9trico consiste en diluciones de la muestra a partir de una muestra madre, a\u00f1adir la muestra en la cubeta e introducir en el espectrofot\u00f3metro para que lo pueda leer, finalmente obtenemos una recta de calibrado que de esa recta que se puede calcular la concentraci\u00f3n de la muestra por interpolaci\u00f3n en la recta comparando la absorbancia de los patrones frente a su concentraci\u00f3n de NO<sub>2<\/sub><sup>\u2014<\/sup>N.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone  wp-image-2965\" src=\"http:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-content\/uploads\/usu644\/2016\/05\/recta.jpg\" alt=\"recta\" width=\"271\" height=\"161\" srcset=\"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-content\/uploads\/usu644\/2016\/05\/recta.jpg 388w, https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-content\/uploads\/usu644\/2016\/05\/recta-300x179.jpg 300w\" sizes=\"auto, (max-width: 271px) 100vw, 271px\" \/><\/p>\n<p><strong>Fuente 2:<\/strong> Recta de calibrado<\/p>\n<p>El \u00a0m\u00e9todo colorim\u00e9trico es adecuado para concentraciones de 5 a 1000 \u00b5g de NO<sub>2<\/sub><sup>&#8211;<\/sup>\u00a0&#8211; N\/L.Los iones siguientes interfieren debido a precipitaci\u00f3n en las condiciones de la prueba y deben estar ausentes: Sb<sup>3+<\/sup>, Au<sup>3+<\/sup>, Bi<sup>3+<\/sup>,\u00a0Fe<sup>3+<\/sup>,\u00a0Pb<sup>2+<\/sup>,\u00a0Hg<sup>2+<\/sup>,\u00a0Ag<sup>+<\/sup>, cloroplatinato (PtCl<sub>6<\/sub><sup>2-<\/sup>) y metavanadato \u00a0(VO<sub>3<\/sub><sup>2-<\/sup>).<\/p>\n<p>El nitrito (NO<sub>2<\/sub><sup>&#8211;<\/sup>) se determina por la formaci\u00f3n de un colorante azo p\u00farpura rojizo producido a pH 2,0-2,5 por acoplamiento de sulfanilamida diazotizada con diclorhidrato de N-(1-naftil)-etilendiamina (diclorhidrato de NED). El rango de aplicaci\u00f3n del m\u00e9todo para medidas espectrofotom\u00e9tricas es de 10 a 1000 \u00b5g de NO<sub>2<\/sub><sup>&#8211;<\/sup>-N\/L y se puede aplicar al de 5 a 50 \u00b5g de N\/L si se usa un recorrido de luz de 5 cm y un filtro de color verde. Diluyendo las muestras se pueden determinar concentraciones m\u00e1s altas de NO<sub>2<\/sub><sup>&#8211;<\/sup>.<\/p>\n<p>Esta es una de las t\u00e9cnicas m\u00e1s utilizadas \u00a0y la que casi todos los d\u00edas preparo en mis pr\u00e1cticas.<a href=\"http:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-content\/uploads\/usu644\/2016\/05\/imagenn.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone  wp-image-2963\" src=\"http:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-content\/uploads\/usu644\/2016\/05\/imagenn.jpg\" alt=\"imagenn\" width=\"215\" height=\"216\" srcset=\"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-content\/uploads\/usu644\/2016\/05\/imagenn.jpg 597w, https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-content\/uploads\/usu644\/2016\/05\/imagenn-150x150.jpg 150w, https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-content\/uploads\/usu644\/2016\/05\/imagenn-300x300.jpg 300w\" sizes=\"auto, (max-width: 215px) 100vw, 215px\" \/><\/a><\/p>\n<p>&nbsp;<\/p>\n<p><strong>Fuente 3<\/strong>: \u00a0Fot\u00f3metro filtro port\u00e1til<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone  wp-image-2964\" src=\"http:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-content\/uploads\/usu644\/2016\/05\/imageeen.jpg\" alt=\"imageeen\" width=\"332\" height=\"220\" srcset=\"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-content\/uploads\/usu644\/2016\/05\/imageeen.jpg 400w, https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-content\/uploads\/usu644\/2016\/05\/imageeen-300x200.jpg 300w\" sizes=\"auto, (max-width: 332px) 100vw, 332px\" \/><\/p>\n<p><strong>Fuente 4:<\/strong>\u00a0Espectrofot\u00f3metro<\/p>\n","protected":false},"excerpt":{"rendered":"<p>El nitr\u00f3geno es un elemento muy abundante en la atm\u00f3sfera donde alcanza casi un 80% en volumen. En los seres [&hellip;]<\/p>\n","protected":false},"author":40,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[173],"tags":[284,285],"class_list":["post-2962","post","type-post","status-publish","format-standard","hentry","category-modul-a","tag-c4","tag-tecniques-danalisi"],"post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-json\/wp\/v2\/posts\/2962","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-json\/wp\/v2\/users\/40"}],"replies":[{"embeddable":true,"href":"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-json\/wp\/v2\/comments?post=2962"}],"version-history":[{"count":3,"href":"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-json\/wp\/v2\/posts\/2962\/revisions"}],"predecessor-version":[{"id":3103,"href":"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-json\/wp\/v2\/posts\/2962\/revisions\/3103"}],"wp:attachment":[{"href":"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-json\/wp\/v2\/media?parent=2962"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-json\/wp\/v2\/categories?post=2962"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/agora.xtec.cat\/ies-merce-rodoreda\/wp-json\/wp\/v2\/tags?post=2962"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}