Examinando por Materia "ESPECTROMETRIA DE ABSORCION ATOMICA"

Mostrando1 - 3 de 3
  • Artículo de Publicación Periódica
    Composite materials based on hybrid mesoporous solids for flow through determination of ultratrace levels of Cd(II)
    (2018-07) Minaberry, Yanina Susana; Stripeikis, Jorge; Tudino, Mabel Beatriz
    "In this work we present a solid phase extraction (SPE) flow through system coupled to graphite furnace atomic absorption spectrometry (GFAAS) for the determination of Cd(II) at ultratrace levels. The flow system holds a minicolumn which was filled, one in turn, with three different lab made materials: a) mesoporous silica functionalized with 3-aminopropyl groups from 3-aminopropyl triethoxysilane (HMS); b) HMS with a resin, Amberlite IR120; c) HMS-Amberlite IR120 and polyvinyl alcohol (PVA). All the solids were characterized by FTIR and SEM. Batch experiments were performed in order to study the optimum adsorption pH, the adsorption kinetics and the maximum adsorption capacity.The materials were compared in terms of their aptitude for the pre-concentration of the analyte under dynamic conditions. Microvolumes of HCl were employed for the release of cadmium and its introduction into the electrothermal atomizer. The operational variables of the flow system were also tested and optimized. The comparison of the figures of merit revealed HMS-A-PVA as the best option from an analytical point of view: limit of detection= 4.7 ng L-1, limit of quantification= 16 ng L-1, RSD %= 4 (n =6, 100 ng L-1), linear range: from LOQ up to 200 ng L-1 and a lifetime over 600 cycles with no obstructions to the free movement of fluids, material bleeding or changes on the analytical sensitivity. The proposed method was shown to be tolerable to several ions typically present in natural waters and was successfully applied to determination of trace of Cd(II) in real samples. A full discussion of the main findings with emphasis on the interaction metal ion/fillings will be provided."
  • Artículo de Publicación Periódica
    A novel combination of experimental design and artificial neural networks as an analytical tool for improving performance in thermospray flame furnace atomic absorption spectrometry
    (2016-02) Morzan, Ezequiel; Stripeikis, Jorge; Goicoechea, Héctor; Tudino, Mabel Beatriz
    "In this work, we present the combined effect of artificial neural networks (ANN) and experimental design as a suitable analytical tool for improving the performance of thermospray flame furnace atomic absorption spectrometry (TS-FFAAS) using Mg as leading case. To this end, mixtures of different amounts of methanol, ethanol, and i-propanol in water were assayed as carriers at different flow rates and different flame stoichiometries (air/acetylene ratios). Different levels of these variables determined the experimental domain, consisting in a cube which was divided into eight identical cubical regions that allowed increase in the number of available experimental points. A Box–Behnken design (BBD) was employed in each one of the regions. The name Multiple Box–Behnken design (MBBD) was given to this new approach. Then, the features of ANN were exploited to find the optimum conditions for conducting Mg determination by TS-FFAAS. The prediction capability of ANN was examined and compared to the least-squares (LS) fitting when applied to the response surface method (RSM). The suitability of the new approach and the implications on TS-FFAAS analytical performance are discussed."
  • Artículo de Publicación Periódica
    Selective determination of Cr (VI) by on-line solid phase extraction FI-SPE-FAAS using an ion exchanger resin as sorbent: an improvement treatment of the analytical signal
    (2017-01) Rossi, Ezequiel; Errea, María Inés; Fidalgo de Cortalezzi, María Marta; Stripeikis, Jorge
    "A flow injection (FI) technique based on an on-line solid phase extraction (SPE) coupled with flame atomic absorption spectroscopy (FAAS) to selectively quantify chromium (VI) in the presence of chromium (III) was developed. An anion exchanger was used as solid sorbent and the detection limit found was two order of magnitude lower than that expected quantifying by FAAS. Until now, quantitative determinations in FAAS were carried out by measuring the height of the peaks rather than their area. In our hands, the software was reconfigured and the area under the peaks could be measured. Considering area instead of height, the enhancement factor increases from 6.7 to 360 (approx. 54 times) giving a detection limit of 0.034 μg·L − 1 , lower than that obtained using much more expensive instruments such as electrothermal atomic absorption spectrometry (ETAAS) or inductively coupled plasma-atomic emission spectrometry (IPC-AES), greatly enhancing the potential of this methodology for future use in speciation studies. The operation conditions were: pH 3, sample loading 50 mL·min − 1 , elution flow rate 7.5 mL·min − 1 . The anion exchanger lifetime was over 100 adsorption/desorption cycles. Anions commonly present in natural aqueous systems did not interfere in the chromium retention. The accuracy was validated using a certified reference material (Fluka Analytical, QC3453)."