http://hdl.handle.net/10498/6827 2026-11-04T18:08:28Z 2026-11-04T18:08:28Z Cuervo Novas, Senia Mendiguchía Martínez, Carolina Moreno Aguilar, Carlos http://hdl.handle.net/10498/40523 2026-10-31T05:04:17Z 2026-01-01T00:00:00Z

A dual solid and liquid solvent bar microextraction coupled with portable X-ray fluorescence for lead determination in seawater Cuervo Novas, Senia; Mendiguchía Martínez, Carolina; Moreno Aguilar, Carlos Trace metals play a crucial role in many biogeochemical processes in water. Due to their low concentrations and the complexity of the matrix, analysing these metals in seawater is a complex task that usually requires a previous preconcentration step. We present a simple two-step method for determining lead concentration in seawater. In the first step, we use a two-phase solvent bar microextraction system (2-SBME), previously prepared with a polypropylene hollow fiber. The extracted metal is then measured directly within the solid fiber using a portable X-ray fluorescence spectrometer. The 2-SBME contains two different extraction reagents: one liquid (Cyanex 272) and one solid (carbon nanotubes functionalized with carboxylic groups (CNT-COOH)). Two different microextraction processes are then carried out simultaneously: a LPME and a SPME, achieving a synergistic effect in the separation process. Efficiency was evaluated in terms of the percentage of lead extracted, with optimum conditions obtained at 0.06 mol L−1 of Cyanex 272, 10 mg mL−1 of CNT-COOH, a stirring rate of 50 rpm and an extraction time of 90 min. The influence of X-ray exposure time was also studied. Under optimal conditions, the LOD and LOQ were 0.061 mg L−1 and 0.203 mg L−1, respectively. Finally, the greenness of the new method was evaluated using the AGREEprep and SPMS methods. The method was successfully used to determine the lead concentration in fortified real seawater samples from three different locations, thus demonstrating its applicability. Using portable X-ray fluorescence equipment avoids the re-extraction step, and opens the possibility of in situ analysis.

2026-01-01T00:00:00Z Perales Pérez, Ángela Pinto Ganfornina, Juan José Moreno Aguilar, Carlos http://hdl.handle.net/10498/40513 2026-10-31T05:04:34Z 2026-01-01T00:00:00Z

A new polymer inclusion membrane-based system to separate and determine copper ions in saline waters Perales Pérez, Ángela; Pinto Ganfornina, Juan José; Moreno Aguilar, Carlos We present a new system to separate and determine copper concentration in saline samples. It is based on the use of a polymer inclusion membrane (PIM) to separate and preconcentrate the copper ions from the saline aqueous matrix to a receiving acidic solution. The influence of the composition and thickness of the PIM has been studied and optimised, by varying the concentration of the base polymer, extractant reagent, and plasticizer, as well as the total volume of solution used to prepare the membrane. The thinner PIM exhibited the best transport of metal ions, with the optimal thickness of 20.5 ± 1.8 μm and the composition being 30% (w/w) of cellulose triacetate (CTA), 60% (w/w) of di(2-ethylhexyl) phosphoric acid (DEHPA), and 10% (w/w) of tris(2-ethylhexyl) phosphate (TEHP). In addition, we studied the influence of the physico-chemical variables on copper transport across the membrane. Optimum results were obtained for a sample pH of 5 and a stripping phase containing 0.1 mol L−1 HNO3. The variation of copper concentration was monitored on-line by using a colorimetric reagent containing 6.67x10−5 mol L−1 of 4-(2-pyridylazo) resorcinol (PAR) in a flow injection analysis (FIA) system. A second-order mathematical relationship was obtained between the extraction time and the percentage of copper separation, enabling the application of the method to real seawater samples with different copper concentrations at the ppm and sub-ppm levels.

2026-01-01T00:00:00Z Quintana González, Juan José Medina Olivera, Antonio Jesús Manzorro Ureba, Ramón Pardanaud, Cedric Hungría Hernández, Ana Belén Cubillana Aguilera, Laura Palacios Santander, José María Hernández Garrido, Juan Carlos Lajaunie, Luc Cyrille Jacques http://hdl.handle.net/10498/40453 2026-10-27T05:03:16Z 2024-01-02T00:00:00Z

Defects engineering of Au@MoS2 nanostructures for conventional and plasmon-enhanced hydrogen evolution reaction Quintana González, Juan José; Medina Olivera, Antonio Jesús; Manzorro Ureba, Ramón; Pardanaud, Cedric; Hungría Hernández, Ana Belén; Cubillana Aguilera, Laura; Palacios Santander, José María; Hernández Garrido, Juan Carlos; Lajaunie, Luc Cyrille Jacques The influence of thermal treatment under reducing conditions on the structural and hydrogen evolution reaction (HER) properties of Au@MoS2 structures is reported in this work. After a thermal treatment at 800 °C under H2 atmosphere, the Au@MoS2 nanostructures exhibit remarkable performance with an overpotential of 203 mV vs reversible hydrogen electrode (RHE) at 10 mA/cm2 and a Tafel slope of 55 mV/dec which is similar to the value reported for edges sites in MoS2. The samples were investigated by combining ex-situ and in-situ aberration-corrected transmission electron microscopy (TEM) experiments under controlled atmosphere, Raman and XPS spectroscopies. (S) TEM characterization highlights the formation of the core-shell system as well as the decrease of the number of shell layers up to incomplete layers induced by the thermal treatments. The plasmonic-assisted HER performances of these nanostructures under LED illumination are also explored and an enhancement by about 10 % of the current density, depending on the wavelength used, is also reported. These results open new avenues for the design of core shell nanostructures based on transition metal dichalcogenides for the hydrogen evolution reaction.

2024-01-02T00:00:00Z Sainz Calvo, Álvaro Jesús Cordero Hernández, Álvaro Jiménez Rodríguez, Marina García Rodriguez, Virginia García Guzmán, Juan José Bellido Milla, Dolores Palacios Santander, José María Cubillana Aguilera, Laura http://hdl.handle.net/10498/40127 2026-07-30T04:00:53Z 2026-01-01T00:00:00Z

Integrated microfluidic platform based on potentiometric Sonogel-Carbon sensors for the simultaneous determination of Na+ and K+ in untreated human plasma and serum Sainz Calvo, Álvaro Jesús; Cordero Hernández, Álvaro; Jiménez Rodríguez, Marina; García Rodriguez, Virginia; García Guzmán, Juan José; Bellido Milla, Dolores; Palacios Santander, José María; Cubillana Aguilera, Laura In the present work, two potentiometric sensors for the simultaneous determination of sodium and potassium ions were successfully developed. A novel functionalized multi-walled carbon nanotube sonogel-based mixture served as ion-to-electron transducer, while sodium and potassium cocktail membranes were employed as ion-selective membranes. Both sensors exhibit a well-defined operational range suitable for the precise quantification of these cations in the biomedical range, the sensors showed linear ranges of 38–4400 and 0.31–314 mM for sodium and potassium, respectively. The LOD and LOQ were 0.28/0.31 mM and 0.38/0.64 mM, respectively while the sensitivities were 58.3 ± 0.5 and 54 ± 0.2 mV per decade. The sensors demonstrate outstanding repeatability, reproducibility, and reversibility, with relative standard deviations (% RSD) below 5%, as well as exceptional selectivity for Na+ and K+ ions in the presence of various interferent substances commonly found in biological matrices. Furthermore, the sensors were applied for the simultaneous determination of sodium and potassium in untreated human plasma and serum samples under continuous flow conditions using a microfluidic cell, whose fabrication is really simple using 3D printing and cost of fabrication is less than 1 euro, and requiring only a minimal sample volume (∼300 μL). The analytical results obtained showed an error margin of less than 5% across all tested samples, highlighting the sensor's reliability and potential applicability in clinical diagnostics. Notably, an excellent correlation was observed with the reference technique routinely employed in hospitals, the blood gas analyser, further supporting clinical relevance of the sensors. These findings underscore the practical utility of the developed sensors for rapid and accurate ion monitoring in complex biological fluids.

2026-01-01T00:00:00Z