Solid-phase extraction of vanadium(V) from teainfusions and wines on immobilized nanometer titanium dioxide followed by ICP-OES analysis

Nanosized titanium dioxide immobilized on silica gel was synthesized and used as fixedbed phase for V(V) pre-concentration, followed by inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis. Three different sorbents were prepared by sol\u2013gel method starting from a mixture of titanium isopropoxide, 2-propanol and water, and characterized by X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and BET analysis. V(V), the most stable and toxic oxidation state of the element, present in water and beverages samples, was selectively sorbed, pre-concentrated, quantitatively eluted by 0.1 M HCl and analyzed by ICP-OES. The effectiveness of the procedure was first assessed on tap water enriched with 1 lg L1 of V(V) obtaining recoveries up to 92% (n= 4). The pre-concentration step was then optimized for complex matrices such as tea infusions and red and white wines. The reliability of the procedure was assessed on the same beverages samples spiked with 20\u2013250 lg L1. Quantitative recoveries (82\u2013 95%, n= 4) were assured avoiding any sample pre-treatment, generally essential in such complex matrices, obtaining good precision (RSD< 12%, n= 3). The method was then applied to the determination of V(V) in commercial tea infusions and wines

Solvent-free microwave-assisted extraction of fluoroquinolones from soil and liquid chromatography-fluorescence determination

Presented hereafter is a novel method entailing solvent free microwave-assisted extraction (MAE) and HPLC equipped with Fluorimetric Detector (HPLC-FD) for the simultaneousdetermination at ugkg−1 concentration of eight fluoroquinolone antibiotics (FQs) (Ciprofloxacin, Danofloxacin, Enrofloxacin, Flerofloxacin, Levofloxacin, Marbofloxacin, Norfloxacin and Orbifloxacin) in agricultural soils. The extraction was quantitatively performed, in a single step, by using an aqueous solution containing Mg(II) as complexing agent, thus avoiding consumption of organic solvents. The optimal MAE conditions have been established through a chemometric approach by considering temperature, irradiation time and matrix moisture or solvent, as the most important recognized variables affecting the extraction yield. Satisfying recoveries (69–110%, spikes 0.03–0.5mgkg−1) were gained with a single MAE cycle of 20 min, at 80 ◦C in 20% (w/v) Mg(NO3)2 solution as leaching agent. MAE-SPE recoveries at 10 ugkg−1, concentration near method quantification limits (MQLs), were in the range 60–85%. Good repeatability and within-lab reproducibility were observed (both in the range 1–16%). The applicability of the method to real samples was assessed on natural contaminated soils. Compared to ultrasonic-assisted extraction (UAE), MAE was shown to be highly competitive in terms of extraction efficacy and analysis speed

Sunlight photodegradation of Marbofloxacin and Enrofloxacin adsorbed on clay minerals

Fluoroquinolone antibiotics (FQs) are important “emerging” micropollutants, and their environmental diffusion is an issue of great concern. In this study, the photochemical degradation of marbofloxacin (MAR) and enrofloxacin (ENR) adsorbed on montmorillonite (MMT) and kaolinite (KAO) clays was investigated. Being FQs photosensitive molecules, the sunlight-induced degradation of clay-adsorbed FQs and of their photoproducts was monitored as function of irradiation time. The photoproducts were identified by high performance liquid chromatography electrospray tandem mass spectrometry (HPLC-ESI-MS/MS) and the photochemical pathways have been elucidated. X-ray diffraction (XRD) has been employed to deeply study the solid-state photodegradation process of MAR and ENR on MMT. Interestingly, the XRD results clearly evidenced a significative variation of the interlayer spacing of MMT not only as function of FQs adsorbed amounts, but also in relationship with their photodegradation, not investigated by means of XRD as yet. The results confirmed that FQs adsorption is a bulk phenomenon that occurs in the interlayer spacing of the MMT structure; moreover, it was proved that sunlight largely degraded the adsorbed FQs, both on the external surface and in the interlayer spacing

Solid-phase extraction of vanadium (V) from tea infusions and wines on immobilized nanometer titanium dioxide followed by ICP-OES analysis

Abstract Nanosized titanium dioxide immobilized on silica gel was synthesized and used as fixed-bed phase for V (V) pre-concentration, followed by inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis. Three different sorbents were prepared by sol- gel method starting from a mixture of titanium isopropoxide, 2-propanol and water, and characterized by X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and BET analysis

Clay minerals for adsorption of veterinary FQs: Behavior and modelling.

The adsorption of two veterinary fluoroquinolones, Enrofloxacin (ENR) and, for the first time, Marbofloxacin (MAR), was investigated on kaolinite and montmorillonite clays with the aim of evaluating the efficiency of these adsorbents in removing pharmaceuticals from soils and waters. Experiments were carried out at two different pHs in tap water and aqueous salt solution. Adsorption isotherms show that these drugs were adsorbed in remarkable amounts by the three materials examined (STx-1, SWy-1, kaolinite) with different mechanisms, as confirmed by XRD (X-ray diffraction) analysis. Different thermodynamicmodels have been applied and the best fit was obtained by means of Langmuir interactions models. In order to remove FQs from contaminated wastewaters, the three clays were contacted with water samples collected from ditches near cattle and swine farms obtaining a quantitative removal. The results proved that such minerals are suitable for the remediation of environmental matrices