Browsing Química by Title
Now showing items 1-20 of 313
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A comparison between the determination of free Pb(II) by two techniques: Absence of gradients and Nernstian equilibrium stripping and resin titration
(Elsevier, 2007)Absence of gradients and Nernstian equilibrium stripping (AGNES) is an emerging electroanalytical technique designed to measure free metal ion concentration. The practical implementation of AGNES requires a critical selection ... -
A focus on the biosynthesis and composition of cuticle in fruits
(American Chemical Society, 2015-04-29)Cuticles are plant structures, composed mostly by lipidic layers, synthesized by nonwoody aerial plant organs and deposited on the surface of outer epidermal cell walls. Although its significance has been often disregarded, ... -
A novel carotenoid, 4-keto-a-carotene, as an unexpected by-product during genetic engineering of carotenogenesis in rice callus
(Elsevier, 2014)Rice endosperm is devoid of carotenoids because the initial biosynthetic steps are absent. The early carotenogenesis reactions were constituted through co-transformation of endosperm-derived rice callus with phytoene ... -
A rapid and reliable direct method for quantifying meat acylglycerides with monomode microwave irradiation
(Elsevier, 2009)A rapid methodology for direct analysis of meat acylglycerides is proposed. A transesterification is carried out in a microwave reactor consisting of a monomode oven using chlorotrimethylsilane (CTMS) and methanol. ... -
A rapid gas chromatographic injection-port derivatization method for the tandem mass spectrometric determination of patulin and 5-hydroxymethylfurfural in fruit juices
(Elsevier, 2016)A novel method consisting of injection-port derivatization coupled to gas chromatography–tandem mass spectrometry is described. The method allows the rapid assessment of 5-hydroxymethylfurfural (HMF) and patulin content ... -
A review on electrochemical methods for trace metal speciation in environmental media
(Elsevier, 2017)Trace metal speciation is key to understand/predict bioavailability and potential toxicity of metals to biota and will, undoubtedly, be incorporated in future regulations. Electroanalytical methods have a role to play in ... -
A semi-grand canonical Monte Carlo simulation model for ion binding to ionizable surfaces: Proton binding of carboxylated latex particles as a case study
(American Institute of Physics, 2011)In this paper, we present a computer simulation study of the ion binding process at an ionizable surface using a semi-grand canonical Monte Carlo method that models the surface as a discrete distribution of charged and ... -
A tandem Finkelstein-rearrangement–elimination reaction: a straightforward synthetic route to allyl esters
(Elsevier, 2009)Allyl esters can be obtained by a Finkelstein-rearrangement–elimination reaction of 2-chloro-1-(chloromethyl)ethyl esters induced by NaI. Sodium iodide can be used below equivalence using a reductive agent as sodium ... -
Absence of Gradients and Nernstian Equilibrium Stripping (AGNES) for the determination of [Zn2+] in estuarine waters
(Elsevier, 2016-03-17)Zinc (Zn) has been classified as a 'Specific Pollutant' under Annex VIII of the EU Water Framework Directive by two thirds of the EU member states. As a result, the UK Environmental Quality Standard (EQS) for Transitional ... -
Absence of Gradients and Nernstian Equilibrium Stripping (AGNES): An Electroanalytical Technique for Chemical Speciation: A Tutorial Review
(MDPI, 2022)Free metal ion concentrations of amalgamating elements such as Zn, Cd, In, or Pb can be determined with absence of gradients and Nernstian equilibrium stripping(AGNES) in a variety of matrices, ranging from seawater to ... -
Accumulation of Mg to Diffusive Gradients in Thin Films (DGT) devices: Kinetic and thermodynamic effects of the ionic strength
(American Chemical Society, 2016-09-23)Availability of magnesium is a matter of concern due to its role in many environmental and biological processes. Diffusive Gradients in Thin Films (DGT) devices can measure Mg availability in situ. This work shows that Mg ... -
Acid-base properties of brown seaweed biomass considered as a Donnan gel. A model reflecting electrostatic effects and chemical heterogeneity
(American Chemical Society, 2003)Brown seaweeds are interesting materials to be used as biosorbents for heavy metals due to their high binding ability and low cost. The study of the passive biosorption of protons on this kind of materials and its ... -
Acid-base properties of dissolved organic matter extracted from the marine environment
(Elsevier, 2020-08-10)Marine dissolved organic matter (DOM) plays a key role in the current and future global carbon cycle, which supports life on Earth. Trace metals such as iron, an essential micronutrient, compete with protons and major ions ... -
Actividad biológica de la azadiractina sobre Nezara viridula (L.)
(Espanya. Ministerio de Medio Ambiente y Medio Rural y Marino, 1996)Se ha estudiado la acción reguladora del desarrollo de diferentes dosis de azadiractina, aplicadas tópicamente sobre ninfas Nezara viridula (L.) de 5 o estadio. Igualmente se ha evaluado la fecundidad y la fertilidad de ... -
Acylation of chiral alcohols: a simple procedure for chiral GC analysis
(Hindawi Publishing Corporation, 2012)The use of iodine as a catalyst and either acetic or trifluoroacetic acid as a derivatizing reagent for determining the enantiomeric composition of acyclic and cyclic aliphatic chiral alcohols was investigated. Optimal ... -
Affinity distribution functions in multicomponent heterogeneous adsorption. Analytical inversion of isotherms to obtain affinity spectra
(American Institute of Physics, 2004)An analytical approach for the interpretation of multicomponent heterogeneous adsorption or complexation isotherms in terms of multidimensional affinity spectra is presented. Fourier transform, applied to analyze the ... -
AGNES at vibrated gold microwire electrode for the direct quantification of free copper concentrations
(Elsevier, 2016-05-12)The free metal ion concentration and the dynamic features of the metal species are recognized as key to predict metal bioavailability and toxicity to aquatic organisms. Quantification of the former is, however, still ... -
AGNES in irreversible systems: The indium case
(Elsevier, 2021)Free indium concentrations can be determined using AGNES (Absence of Gradients and Nernstian Equilibrium Stripping) with no relevant hindrance from the irreversibility of the In3+/In° redox couple at a mercury electrode. ... -
AGNES: a new electroanalytical technique for measuring free metal ion concentration
(Elsevier, 2004)AGNES (absence of gradients and Nernstian equilibrium stripping) is a stripping technique consisting of two conceptual steps: (i) application of a potential program (e.g. a step at a fixed potential) generating a known ... -
AGNES: a technique for determining the concentration of free metal ions. The case of Zn(II) in coastal Mediterranean seawater
(Elsevier, 2007)Absence of Gradients and Nernstian Equilibrium Stripping (AGNES) is a recently suggested electroanalytical technique designed for the determination of the free concentration of heavy metals (such as Zn, Cd or Pb) which is ...