Response mechanism of a neutral carrier Hg(II) polymeric membrane ion-selective electrode. SEM and EDAX study
Pérez-MarÃn, L.; López-Valdivia, H.; Avila-Pérez, P.; Otazo-Sánchez, E.; Macedo-Miranda, G.; Gutiérrez-Lozano, O.; Alonso Chamaro, J.; De la Torres-Orozco, J.; Carapia-Morales, L.; Pérez-MarÃn L.; Instituto Nacional de Investigaciones Nucleares, Departamento de Estudios del Ambiente; López-Valdivia H.; Instituto Nacional de Investigaciones Nucleares, Departamento de Estudios del Ambiente; Avila-Pérez P.; Instituto Nacional de Investigaciones Nucleares, Departamento de Estudios del Ambiente; Otazo-Sánchez E.; Instituto de Materiales y Reactivos, Universidad de la Habana; Macedo-Miranda G.; Instituto Nacional de Investigaciones Nucleares, Departamento de Estudios del Ambiente; Gutiérrez-Lozano O.; Instituto Nacional de Investigaciones Nucleares, Departamento de Estudios del Ambiente; Alonso Chamaro J.; Universidad Autonóma de Barcelona, Grupo de Sensores y Biosensores; De la Torres-Orozco J.; Instituto Nacional de Investigaciones Nucleares, Departamento de Estudios del Ambiente; Carapia-Morales L.; Instituto Nacional de Investigaciones Nucleares, Departamento de Estudios del Ambiente
Журнал:
Analyst
Дата:
2001
Аннотация:
Scanning electron microscopy (SEM) and energy dispersive atomic X-ray spectrometry (EDAX) were used to study the response mechanism of a previously reported new Hg membrane ion-selective electrode (ISE) based on 1,3-diphenylthiourea. These techniques allowed the study of the membrane surface characteristics, such as the morphological homogeneity and chemical composition. A â twice Nernstianâ response at pH â ¥ 7 was explained by the detection of the Hg(OH)<sup>+</sup> cation. A normal Nernstian response was found at acidic pH values. Using these techniques, both coordination compounds, [Ligandâ Hgâ OH] at pH 7 and [Ligandâ Hgâ Ligand] at pH 4.5, were confirmed on the electrode membrane surface activated with Hg(NO3)2 solution at both pH values. These methods provide results which are independent of the potential measurement data and in agreement with them. A successful response model has explained both independent and unbiased sets of results. These conclusions confirm the proposed response mechanisms for this new Hg membrane sensor.
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