title: Non-chromatographic speciation of chromium at sub-ppb levels using cloud point extraction in the presence of unmodified silver nanoparticles.
abstract: The cloud point extraction (CPE) of silver nanoparticles (AgNPs) by Triton X-114 allows chromium (III) ions to be transferred to the surfactant-rich phase, where they can be measured by electrothermal atomic absorption spectrometry. Using 20 mL sample and 50 μL Triton X-114 (30% w/v), the enrichment factor was 1150, and calibration graphs were obtained in the 5-100 ng L(-1) chromium range in the presence of 5 µg L(-1) AgNPs. Speciation of trivalent and hexavalent chromium was achieved by carrying out two CPE experiments, one of them in the presence of ethylenediaminetetraacetate. While in the first experiment, in absence of the complexing agent, the concentration of total chromium was obtained, the analytical signal measured in the presence of this chemical allowed the chromium (VI) concentration to be measured, being that of chromium (III) calculated by difference. The reliability of the procedure was verified by using three standard reference materials before applying to water, beer and wine samples.
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum" University of Murcia, E-30100 Murcia, Spain.
authors.forename: Ignacio
authors.initials: I
authors.lastname: López-García
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum" University of Murcia, E-30100 Murcia, Spain.
authors.forename: Yesica
authors.initials: Y
authors.lastname: Vicente-Martínez
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, Regional Campus of International Excellence "Campus Mare Nostrum" University of Murcia, E-30100 Murcia, Spain. Electronic address: hcordoba@um.es.
authors.forename: Manuel
authors.initials: M
authors.lastname: Hernández-Córdoba
mesh_terms: D001515:Beer / Q000032:analysis; D002138:Calibration; D002857:Chromium / Q000302:isolation & purification*; D017608:Chromium Compounds / Q000302:isolation & purification*; D060766:Drinking Water / Q000737:chemistry; D004492:Edetic Acid / Q000737:chemistry; D006801:Humans; D057230:Limit of Detection; D059625:Liquid-Liquid Extraction / Q000379:methods*; D053768:Metal Nanoparticles / Q000737:chemistry*; D009566:Nitrates / Q000302:isolation & purification*; D017830:Octoxynol; D011092:Polyethylene Glycols / Q000737:chemistry; D012834:Silver / Q000737:chemistry*; D013054:Spectrophotometry, Atomic; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D014920:Wine / Q000032:analysis
chemical_list: D017608:Chromium Compounds; D060766:Drinking Water; D009566:Nitrates; D014874:Water Pollutants, Chemical; D002857:Chromium; C074702:chromium hexavalent ion; D012834:Silver; D011092:Polyethylene Glycols; D017830:Octoxynol; C010615:Nonidet P-40; D004492:Edetic Acid; C041167:chromium nitrate
keywords: Beer; Chromium; Cloud point extraction; ETAAS; Silver nanoparticles; Speciation; Water; Wine