Browsing by Subject "waters"

Now showing 1 - 2 of 2
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    Determination of nitrophenols in environmental samples using stir bar sorptive extraction coupled to thermal desorption gas chromatography-mass spectrometry
    (Elsevier, 2018-11-01) Pastor-Belda, M.; Sánchez-López, M.J.; Campillo, N.; Viñas López-Pelegrín, Pilar; Hernández Córdoba, Manuel; Química Analítica
    This paper presents a procedure for the determination of seven nitrophenols (NPs) in water and soil samples using stir bar sorptive extraction (SBSE) coupled to gas chromatography with mass spectrometry (GC-MS) by means of a thermal desorption unit (TDU). Microwave assisted extraction (MAE) is proposed to release the NPs from the soil matrices into an aqueous phase, prior to their acetylation. The different variables affecting the preconcentration efficiency of SBSE, during both the adsorption and the thermal desorption steps, are studied. As regards the analytical characteristics of the method, the accuracy was measured through recovery studies, recovery percentages in all cases being in the 79–120% range, as well as by analyzing a certified reference material. The precision was evaluated in terms of relative standard deviation, which provided values lower than 15% for both repeatability and reproducibility. The limits of detection were between 0.001 and 0.031 μg L−1 for water and 0.020–0.107 ng g−1 for soil samples. When environmental samples of different origins were analyzed, contents in the 0.01–1.0 μg L−1 and 0.7–40 ng g−1 ranges were obtained for waters and soils, respectively.
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    Open Access
    Speciation of chromium in waters using dispersive micro-solid phase extraction with magnetic ferrite and graphite furnace atomic absorption spectrometry
    (Springer, 2020-03-24) López-García, Ignacio; Marín-Hernández, Juan José; Hernández Córdoba, Manuel; Química Analítica
    The combination of a solid-phase microextraction process with graphite furnace atomic absorption spectrometry provides a very sensitive determination method for determining chromium in waters. Freshly prepared ferrite particles are used to retain the chromium species, and then separated by a magnet without the need for a centrifugation step. The solid phase is suspended in water and directly introduced into the graphite furnace to obtain the analytical signal. The complexation of Cr(III) with ethylenediaminetetraacetate allows the selective retention of Cr(VI), and thus the speciation of the metal. The procedure is sensitive (0.01 µg L−1 detection limit when using a 10 mL sample aliquot) and reproducible (5% relative standard deviation for five consecutive experiments at the 0.3 µg L−1 level). The reliability of the procedure is verified by analysing five certified water samples.