RESUMO
Thiol or sulfonic-functionalized poly(dimethylsiloxane) elastomeric networks were prepared from 3-mercaptopropyltrimethoxysilane or the oxidized silane. The characterization of these materials using infrared spectroscopy (IR) and (13)C/(29)Si nuclear magnetic resonance (NMR) suggested that the materials were functionalized with the aforementioned groups and that the networks are composed of linear segments of PDMS crosslinked by nodes of silsesquioxanes, which contain T(3) and/or T(2) type silicon. The thermogravimetric analysis of the polymeric networks revealed that they exhibit good thermal stability. The adsorption capacities for cadmium ions in ethanolic solutions were 0.33 and 0.89 mmol g(-1) for the thiol- and sulfonic-functionalized PDMS networks, respectively. In water solution the material with thiol group do not adsorbed Cd (II), however, the network with sulfonic group adsorbed 0.70 mmol g(-1). In ethanol, the linearization of the adsorption isotherms revealed that the Langmuir model describes the interaction between the adsorbate-adsorbent, in water, the Freundlich adsorption model described the metal adsorption for the sulfonic-functionalized PDMS.
Assuntos
Cádmio/isolamento & purificação , Dimetilpolisiloxanos/síntese química , Águas Residuárias/química , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Cátions Bivalentes , Cinética , Espectroscopia de Ressonância Magnética , Espectroscopia de Infravermelho com Transformada de Fourier , Compostos de Sulfidrila/química , Ácidos Sulfônicos/química , TermogravimetriaRESUMO
A new polymeric coating consisting of a dual-phase, polydimethylsiloxane (PDMS) and polypyrrole (PPY) was developed for the stir bar sorptive extraction (SBSE) of antidepressants (mirtazapine, citalopram, paroxetine, duloxetine, fluoxetine and sertraline) from plasma samples, followed by liquid chromatography analysis (SBSE/LC-UV). The extractions were based on both adsorption (PPY) and sorption (PDMS) mechanisms. SBSE variables, such as extraction time, temperature, pH of the matrix, and desorption time were optimized, in order to achieve suitable analytical sensitivity in a short time period. The PDMS/PPY coated stir bar showed high extraction efficiency (sensitivity and selectivity) toward the target analytes. The quantification limits (LOQ) of the SBSE/LC-UV method ranged from 20 ng mL(-1) to 50 ng mL(-1), and the linear range was from LOQ to 500 ng mL(-1), with a determination coefficient higher than 0.99. The inter-day precision of the SBSE/LC-UV method presented a variation coefficient lower than 15%. The efficiency of the SBSE/LC-UV method was proved by analysis of plasma samples from elderly depressed patients.