Tandem on-line continuous separations for atomic spectroscopic indirect analysis: Iodide determination by ICP-AES |
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Authors: | Alberto Menéndez García José Enrique Sánchez Uría Alfredo Sanz-Medel M. Carmen Quintero Ortega José Cotrino Bautista |
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Affiliation: | (1) Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, E-33006 Oviedo, Spain;(2) Department of Applied Physics Faculty of Sciences, University of Crdoba, E-14004 Córdoba, Spain |
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Abstract: | A sensitive and selective indirect determination of iodide by inductively coupled plasma emission spectrometry (ICP-AES) based on the principle of tandem on-line continuous separations as an alternative means of introducing samples into plasmas is proposed. Iodide is continuously extracted as an ion-pair into xylene by mixing the sample with Hg(II) and dipyridil solutions. The organic phase (containing the analyte in [Hg(Dipy)2]I2 form) is on-line continuously mixed with NaBH4 (in DMF) and acetic acid solutions. Mercury vapour continuously generated from this organic phase is separated in a classical U-type gas-liquid separation device. The system has been optimized for the continuous extraction of KI, for the direct generation of cold mercury vapour from xylene and for the final ICP-AES determination of mercury. The optimised method has been applied to the determination of iodide (detection limit 20 ng/ml of iodide) in table salt and in synthetic samples. Very good agreement between found and certified results was observed. The usefulness and convenience of such alternative sample chemical pretreatment/presentation to the ICP is thus demonstrated for indirect determinations to be carried out by atomic spectroscopy methods. |
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Keywords: | iodide tandem on-line separations liquid-liquid extraction on-line generation inductively coupled plasma |
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