Artículos (Química Analítica)

URI permanente para esta colecciónhttps://hdl.handle.net/11441/10909

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Diclofenac Removal by Alkylammonium Clay Minerals Prepared over Microwave Heating
(American Chemical Society, 2024-11-23) França, Denise B.; Silva, Alice P. N.; Osajima, Josy A.; Silva-Filho, Edson C.; Medina Carrasco, Santiago; Orta Cuevas, María del Mar; Jaber, Maguy; Fonseca, Maria G.; Universidad de Sevilla. Departamento de Química Analítica; Universidad de Sevilla
Diclofenac is an emerging contaminant widely detected in water and has had adverse effects on the biota. In this study, the adsorbents were prepared by reacting tetradecyl-(C14), hexadecyl-(C16), and octadecyltrimethylammonium (C18) bromides with sodium vermiculite (Na-Ver) and used for the removal of the first time for diclofenac sodium from aqueous solution. Synthesis was carried out in a microwave-assisted reactor operating at 50 °C for 5 min, using proportions of organic salts in 100 and 200% of the phyllosilicate cation exchange capacity. The stability of loaded alkylammonium solids was evaluated under drug adsorption conditions. Adsorption was mainly influenced by the amount of surfactant incorporated into the clay mineral according to the thermogravimetric and CHN elemental analysis data. Samples prepared with 200% CEC presented lower stability at pH 6.0 and 8.0. Drug adsorption was more effective for C14-Ver-200%, C16-Ver-200%, and C18-Ver-200% samples, with a maximum retention of 97.8, 110.1, and 108.0 mg g–1, respectively. The adsorptive capacities of C14-Ver-200%, C16-Ver-200%, C18-Ver-200%, C14-Ver-100%, C16-Ver-100%, and C18-Ver-100% were reduced to 29.0, 36.8, 41.0, 61.0, 50.4, and 58.0%, respectively, compared with their initial value after three adsorption cycles. X-ray diffraction (XRD) patterns revealed that diclofenac was adsorbed into the interlayer region of organovermiculites. Fourier transform infrared spectroscopy (FTIR), Zeta potential results, and the pH study of adsorption indicated that van der Waals interactions are dominant in the adsorption mechanism.
Multiclass Analysis for the Determination of Pharmaceuticals and Their Main Metabolites in Leafy and Root Vegetables
(Multidisciplinary Digital Publishing Institute (MDPI), 2024-07-24) Mejías Padilla, Carmen; Arenas Molina, Marina; Martín Bueno, Julia; Santos Morcillo, Juan Luis; Aparicio Gómez, Irene; Alonso Álvarez, Esteban; Universidad de Sevilla. Departamento de Química Analítica; Ministerio de Ciencia, Innovación y Universidades (MICINN). España; Agencia Estatal de Investigación (AEI)
The irrigation of soils with reclaimed contaminated wastewater or its amendment with sewage sludge contributes to the uptake of pharmaceuticals by vegetables growing in the soil. A multiresidue method has been devised to determine five pharmaceuticals and nine of their main metabolites in leafy and root vegetables. The method employs ultrasound-assisted extraction, clean-up via dispersive solid-phase extraction, and analysis through liquid chromatography–tandem mass spectrometry. Box–Behnken design was used to refine variables such as extraction solvent volume, time of extraction, number of extraction cycles, and the type and amount of d-SPE sorbent. The method achieved linearity (R2) greater than 0.994, precision (relative standard deviation) under 16% for most compounds, and detection limits ranging from 0.007 to 2.25 ng g−1 dry weight. This method was applied to a leafy vegetable (lettuce) and to a root vegetable (carrot) sourced from a local market. Parent compounds were detected at higher concentrations than their metabolites, with the exception of carbamazepine-10,11-epoxide.
Bacterial bioaugmentation for paracetamol removal from water and sewage sludge. Genomic approaches to elucidate biodegradation pathway
(Elsevier, 2024-12-05) Lara Moreno, Alba; Vargas Ordóñez, Antonio; Madrid, F.; Carlier, J. D.; Santos Morcillo, Juan Luis; Alonso Álvarez, Esteban; Morillo, E.; Universidad de Sevilla. Departamento de Microbiología y Parasitología; Universidad de Sevilla. Departamento de Biología Vegetal y Ecología; Universidad de Sevilla. Departamento de Química Analítica; Junta de Andalucía; Portuguese National Funds
Wastewater treatment plants (WWTPs) are recognized as significant contributors of paracetamol (APAP) into the environment due to their limited ability to degrade it. This study used a bioaugmentation strategy with Pseudomonas extremaustralis CSW01 and Stutzerimonas stutzeri CSW02 to achieve APAP biodegradation in solution in wide ranges of temperature (10–40 °C) and pH (5−9), reaching DT50 values < 1.5 h to degrade 500 mg L−1 APAP. Bacterial strains also mineralized APAP in solution (<30 %), but when forming consortia with Mycolicibacterium aubagnense HPB1.1, mineralization significantly increased (up to 74 % and 58 % for CSW01 +HPB1.1 and CSW02 +HPB1.1, respectively), decreasing DT50 values to only 1 and 9 days. Despite the complete degradation of APAP and its high mineralization, residual toxicity throughout the process was observed. Three APAP metabolites were identified (4-aminophenol, hydroquinone and trans-2-hexenoic acid) that quickly disappeared, but residual toxicity remained, indicating the presence of other non-detected intermediates. CSW01 and CSW02 degraded also 100 % APAP (50 mg kg−1) adsorbed on sewage sludge, with DT50 values of only 0.7 and 0.3 days, respectively, but < 15 % APAP was mineralized. A genome-based analysis of CSW01 and CSW02 revealed that amidases, deaminases, hydroxylases, and dioxygenases enzymes were involved in APAP biodegradation, and a possible metabolic pathway was proposed.
Unravelling biochemical responses in the species Mytilus galloprovincialis exposed to the antineoplastics ifosfamide and cisplatin under different temperature scenarios
(Elsevier, 2024-09-15) Queirós, Vanessa; Azeiteiro, Ulisses M.; Santos Morcillo, Juan Luis; Alonso Álvarez, Esteban; Soares, Amadeu M.V.M.; Barata, Carlos; Freitas, Rosa; Universidad de Sevilla. Departamento de Química Analítica; Centre for Environmental and Marine Studies. Portugal
This study investigates the chronic impact of two of the most widely consumed antineoplastic drugs, Ifosfamide (IF) and Cisplatin (CDDP), on the bivalve species Mytilus galloprovincialis under current (17 °C) and predicted warming conditions (21 °C). Accompanying the expected increase in worldwide cancer incidence, antineoplastics detection in the aquatic environment is also expected to rise. Mussels were exposed to varying concentrations of IF (10, 100, 500 ng/L) and CDDP (10, 100, 1000 ng/L) for 28 days. Biochemical analyses focused on metabolic, antioxidant and biotransformation capacities, cellular damage, and neurotoxicity. Results showed temperature-dependent variations in biochemical responses. Metabolic capacity remained stable in mussels exposed to IF, while CDDP exposure increased it at 1000 ng/L for both temperatures. Antioxidant enzyme activities were unaffected by IF, but CDDP activated them, particularly at 21 °C. Biotransformation capacity was unchanged by IF but enhanced by CDDP. Nevertheless, cellular damage occurred at CDDP concentrations above 100 ng/L, regardless of temperature. Integrated biomarker responses highlighted CDDP's greater impact, emphasizing the critical role of temperature in shaping organismal responses and underscoring the complexity of environmental stressor interactions.
Polysaccharide Hydroxyapatite (Nano)composites and Their Biomedical Applications: An Overview of Recent Years
(American Chemical Society, 2024-07-02) Barros Costa, Wanderson; Félix Farias, Ana F.; da Silva-Filho, Edson Cavalcanti; Osajima, Josy A.; Medina Carrasco, Santiago; Orta Cuevas, María del Mar; Fonseca, Maria Gardennia; Universidad de Sevilla. Departamento de Química Analítica; Universidad de Sevilla; Consejo Nacional de Desarrollo Científico y Tecnológico. Brasil
Hydroxyapatite can combine with polysaccharide originating biomaterials with special applications in the biomedical field. In this review, the synthesis of (nano)composites is discussed, focusing on natural polysaccharides such as alginate, chitosan, and pectin. In this way, advances in recent years in the development of preparing materials are revised and discussed. Therefore, an overview of the recent synthesis and applications of polyssacharides@hydroxyapatites is presented. Several studies based on chitosan@hydroxyapatite combined with other inorganic matrices are highlighted, while pectin@hydroxyapatite is present in a smaller number of reports. Biomedical applications as drug carriers, adsorbents, and bone implants are discussed, combining their dependence with the nature of interactions on the molecular scale and the type of polysaccharides used, which is a relevant aspect to be explored.
Implications of polystyrene and polyamide microplastics in the adsorption of sulfonamide antibiotics and their metabolites in water matrices
(Elsevier, 2024-06) Mejías Padilla, Carmen; Martín Bueno, Julia; Santos Morcillo, Juan Luis; Aparicio Gómez, Irene; Alonso Álvarez, Esteban; Universidad de Sevilla. Departamento de Química Analítica; Junta de Andalucía; Ministerio de Ciencia e Innovación (MICIN). España
Microplastics (MP) and antibiotics coexist in the environment and their combined exposure represents a source of increasing concern. MP may act as carriers of antibiotics because of their sorption capacity. Knowledge of the interactions between them may help improve understanding of their migration and transformation. In this work, the adsorption behaviour of a group of sulfonamides and their acetylated metabolites on different sizes of polyamide (PA) and polystyrene (PS) MP were investigated and compared. Sulfonamides were adsorbed on both MP (qmax up to 0.699 and 0.184 mg/g, for PA and PS, respectively) fitting to a linear isotherm model (R2 > 0.835). A low particle size and an acidic and salinity medium significantly enhances the adsorption capacity of sulfonamides (i.e. removal of sulfamethoxazole increased from 8 % onto 3 mm PA pellets to 80 % onto 50 mm of PA pellets). According to characterization results, adsorption mechanism is explained by pore filling and hydrogen bonds (for PA) and hydrophobic interactions (for PS). After adsorption, surface area was increased in both MP as result of a potential ageing of the particles and the intensity of XRD peaks was higher denoting a MP structure more amorphized. Metabolites were adsorbed more efficiently than their parent compounds on PS while the opposite effect was observed on PA explained by the acetylation of the amine group and, subsequently the reduction of hydrogen bond interactions. Although the dissolved organic matter inhibits sulfonamides adsorption, removal up to 65.2 % in effluent wastewater and up to 72.1 % in surface water were observed in experiments using real matrices denoting the role of MP as vectors of sulfonamide antibiotics in aquatic media.
Biocompatible metal-organic frameworks as promising platforms to eradicate HIV reservoirs ex vivo in people living with HIV
(Royal Society of Chemistry, 2024-04-17) Lebrón Romero, José Antonio; Ostos Marcos, Francisco José; Martínez-Santa, Marta; García-Moscoso, Francisco; López-López, Manuel; Moyá Morán, María Luisa; Bernal Pérez, Eva; Bachiller, Sara; González-Ulloa, Gabriel; Rodríguez Lucena, David; Lopes-Costa, Tania; Fernández Torres, Rut; Ruiz-Mateos, Ezequiel; Pedrosa, José María; Rafii-El-Idrissi Benhnia, Mohammed; López-Cornejo, María del Pilar; Universidad de Sevilla. Departamento de Química Analítica; Universidad de Sevilla. Departamento de Química Física; Universidad de Sevilla. Departamento de Química orgánica; Universidad de Sevilla. Departamento de Bioquímica Médica y Biología Molecular e Inmunología; Junta de Andalucía; Universidad de Sevilla; Ministerio de Ciencia e Innovación (MICIN). España
The HIV attacks the immune system provoking an infection that is considered a global health challenge. Despite antiretroviral treatments being effective in reducing the plasma viral load in the blood to undetectable levels in people living with HIV (PLWH), the disease is not cured and has become chronic. This happens because of the existence of anatomical and cellular viral reservoirs, mainly located in the lymph nodes and gastrointestinal tract, which are composed of infected CD4+ T cells with a resting memory phenotype and inaccessible to antiretroviral therapy. Herein, a new therapeutic strategy based on nanotechnology is presented. Different combinations of antiretroviral drugs (bictegravir/tenofovir/emtricitabine and nevirapine/tenofovir/emtricitabine) and toll-like receptor agonists were encapsulated into metal-organic frameworks (MOFs) PCN-224 and ZIF-8. The encapsulation efficiencies of all the drugs, as well as their release rate from the carriers, were measured. In vitro studies about the cell viability, the hemocompatibility, and the platelet aggregation of the MOFs were carried out. Epifluorescence microscopy assays confirmed the ability of ZIF-8 to target a carboxyfluorescein probe inside HeLa cell lines and PBMCs. These results pave the way for the use of these structures to eliminate latent HIV reservoirs from anatomical compartments through the activation of innate immune cells, and a higher efficacy of the triplet combinations of antiretroviral drugs.
Adsorption of Macrolide Antibiotics and a Metabolite onto Polyethylene Terephthalate and Polyethylene Microplastics in Aquatic Environments
(Multidisciplinary Digital Publishing Institute (MDPI), 2024-04-29) Mejías Padilla, Carmen; Martín Bueno, Julia; Martín-Pozo, Laura; Santos Morcillo, Juan Luis; Aparicio Gómez, Irene; Alonso Álvarez, Esteban; Universidad de Sevilla. Departamento de Química Analítica; Ministerio de Ciencia e Innovación (MICIN). España
Microplastics (MPs) and antibiotics are emerging pollutants widely found in aquatic environments, potentially causing environmental harm. MPs may act as carriers for antibiotics, affecting their environmental distribution. This study investigates the adsorption of four macrolide antibiotics and a metabolite onto two types of MPs: polyethylene terephthalate (PET) and polyethylene (PE). Results revealed a linear isotherm adsorption model, with higher adsorption to PET than to PE (R2 > 0.936 for PE and R2 > 0.910 for PET). Hydrophobic interactions and hydrogen bonding could be the main adsorption mechanisms, with pore filling potentially involved. Reduced particle size enhances adsorption due to the increase of active adsorption sites. This increasement is more pronounced in PE than in PET, leading to an 11.6% increase in the average adsorption of all macrolides to PE, compared to only 5.1% to PET. Dissolved organic matter inhibits adsorption (azithromycin adsorption to PE was reduced from 12% to 5.1%), while salinity enhances it just until 1% salinity. pH slightly influences adsorption, with maximal adsorption at neutral pH. Results in real samples showed that complexity of the matrix decreased adsorption. Overall, these findings indicate that PE and PET MPs can be a vector of macrolides in aquatic environments.
Usefulness of excitation-emission fluorescence spectralprint combined with chemometrics for authentication of PDO fortified wines
(Elsevier, 2024-04) Ríos-Reina, Rocío; Pérez Bernal, Juan Luis; Azcarate, Silvana M.; Callejón Fernández, Raquel María; Universidad de Sevilla. Departamento de Química Analítica; Universidad de Sevilla. Departamento de Nutrición y Bromatología, Toxicología y Medicina Legal; Junta de Andalucía
Fortified wines covered by a Protected Designation of Origin (PDO) are high-quality products appreciated by consumers, whose diversity has increased in recent years, leading to an increased vulnerability to fraud. In this work, for the first time, an excitation-emission fluorescence spectroscopy method combined with two chemometric approaches was developed for the characterization and authentication of PDO fortified wines. A visual assessment of fluorescence landscapes pointed out different trends. The excitation-emission matrix (EEM) was decomposed using Parallel Factor Analysis (PARAFAC) for the extraction of potential fluorophores, or unfolded, and then, the resulting matrices were subjected to Principal Component Analysis (PCA) and Partial Least Squares-Discriminant Analysis (PLS-DA). Both approaches were able to discriminate the wine type within each PDO, the PDO within a wine type, and the production process. The proposed analytical and chemometric tools could be used as an alternative control method for a rapid screening of Spanish PDO fortified wines.
Synthesis and Characterization of Cassava Gum Hydrogel Associated with Chlorhexidine and Evaluation of Release and Antimicrobial Activity
(Wiley, 2024-06) Lima, Idglan Sa de; Silva, Albert Santos; Nascimento, Ariane Maria Silva Santos; Oliveira, Luis Humberto de; Morais, Alan Icaro Sousa; Barreto, Humberto Medeiros; Peña García, Ramón; Orta Cuevas, María del Mar; Argolo Neto, Napoleao Martins; Osajima, Josy Anteveli; Muniz, Edvani Curti; da Silva-Filho, Edson Cavalcanti; Universidad de Sevilla. Departamento de Química Analítica; Instituto Nacionais de Ciência e Tecnologia, Brasil
Hydrogels from natural sources are attracting increasing interest due to their ability to protect biologically active molecules. Starch extracted from cassava tubers is a promising material for synthesizing these hydrogels. Copolymerization of cassava gum and incorporation of chlorhexidine digluconate (CLX) into the hydrogels is confirmed by changes in the crystallographic profile, as observed through X-ray diffraction, and a shift in the 1000 cm−1 band in the Fourier-transform infrared spectroscopy spectrum. The differential scanning calorimetry reveals changes in the decomposition temperature of the synthesized hydrogels related to CLX volatility. Micrographs illustrate the material's porosity. Release tests indicate a constant linear release over 72 h, while antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans is satisfactory, with 100% effectiveness from 0.5% CLX and the formation of inhibition halos. Toxicity and biocompatibility studies show no cytotoxicity. The continuous release of chlorhexidine is promising for components of biomedical implants and applications as it can ensure antimicrobial action according to specific therapeutic needs.
Pretreatment with Oleuropein Protects the Neonatal Brain from Hypoxia-ischemia by Inhibiting Apoptosis and Neuroinflammation
(Sage, 2024) Reyes Corral, Marta; Gil González, Laura; González Díaz, Ángela; Tovar Luzón, Javier; Ayuso, María Irene; Lao Pérez, Miguel; Montaner, Joan; Puerta Vázquez, Rocío de la; Fernández Torres, Rut; Ybot González, Patricia; Universidad de Sevilla. Departamento de Química Analítica; Universidad de Sevilla. Departamento de Farmacología; Junta de Andalucía; European Union (UE)
Hypoxic-ischemic (HI) encephalopathy is a cerebrovascular injury caused by oxygen deprivation to the brain and remains a major cause of neonatal mortality and morbidity worldwide. Therapeutic hypothermia is the current standard of care but it does not provide complete neuroprotection. Our aim was to investigate the neuroprotective effect of oleuropein (Ole) in a neonatal (seven-day-old) mouse model of HI. Ole, a secoiridoid found in olive leaves, has previously shown to reduce damage against cerebral and other ischemia/reperfusion injuries. Here, we administered Ole as a pretreatment prior to HI induction at 20 or 100 mg/kg. A week after HI, Ole significantly reduced the infarct area and the histological damage as well as white matter injury, by preserving myelination, microglial activation and the astroglial reactive response. Twenty-four hours after HI, Ole reduced the overexpression of caspase-3 and the proinflammatory cytokines IL-6 and TNF-α. Moreover, using UPLC-MS/MS we found that maternal supplementation with Ole during pregnancy and/or lactation led to the accumulation of its metabolite hydroxytyrosol in the brains of the offspring. Overall, our results indicate that pretreatment with Ole confers neuroprotection and can prevent HI-induced brain damage by modulating apoptosis and neuroinflammation.
Insight into the TiO2 Nanostructures Stabilized with Cashew Tree Gum to Remove Emerging Contaminants as a Green Technology
(Elsevier, 2024) Ribeiro, Marcelo Xisto; Araujo, Francisca P.; da Silva-Filho, Edson Cavalcanti; Almeida, Luciano C.; da Silva, Durcilene Alves; Peña Garcia, Ramón R.; Cecilia, Juan Antonio; Furtini, Marcelo Barbosa; Osajima, Josy A.; Orta Cuevas, María del Mar; Universidad de Sevilla. Departamento de Química Analítica
Searching for technologies to combat emerging pollutants such as dyes and pharmaceuticals is arduous. Plant polysaccharides have been used to synthesize photocatalysts as strategies for green technology. The present study aimed to synthesize TiO2 nanostructure photocatalytic using cashew tree gum. Structural, morphological, and optical characterization was carried out to verify the gum's effect on the growth of nanostructures. Photocatalytic tests were performed with Methylene dye (MB) and Ibuprofen (IBP) pollutants under UV irradiation. Structural characterization demonstrated the formation of anatase-type TiO2, with a band gap at 3.15 eV. Photocatalytic assays using CGT showed that the material was more efficient in removing MB (43.17 %) when compared to IBP (29.86 %). In addition, scavenger studies indicated that electrons are the species involved in dye degradation. Therefore, the results are promising for using TiO2 nanoparticles obtained with gum to remove pollutants.
Authentication of organic and conventional eggs by carotenoid profiling
(Elsevier, 2011-06-01) Van Ruth, Saskia; Alewijn, Martin; Rogers, Karyne; Newton-Smith, Elizabeth; Tena Pajuelo, Noelia; Bollen, Mirko; Koot, Alex; Universidad de Sevilla. Departamento de Química Analítica
Organic production benefits from fair competition and sustained consumer confidence. The latter can only be assured by paper trailing and verification assessments. Traditional analytical strategies for guaranteeing quality and uncovering adulteration have relied on the determination of the amount of a marker compound or compounds in a material and a subsequent comparison of the value(s) obtained with those established for equivalent material. Since it is unlikely to find a unique marker that allows discrimination between organic and conventional produce, selective fingerprinting (profiling) combined with chemometrics is a more promising approach. In this study, carotenoid High Performance Liquid Chromatography-Diode Array Detection profiling combined with k-nearest neighbour classification chemometrics was used to predict the production system (organic vs. non-organic) of chicken eggs. A proof-of-concept set (training set for the model) was composed of eggs from 24 organic farms, 12 free range, and 12 barn farms in the Netherlands. The identities of organic, free range, and barn eggs were predicted with success rates of 100%, 100%, and 84%, respectively. The identity of eggs determined using an additional market test set with eggs from 12 organic, 12 free range, and 12 barn farms originating from the Netherlands and New Zealand resulted in correct classifications for 35 of the 36 samples. The results of this study indicate that this fingerprint approach is a promising tool for analytical verification of the production system of organic eggs.
Dual effect of the presence of fruits on leaf gas exchange and water relations of olive trees
(Oxford University Press, 2023-02) Pérez Arcoiza, Adrián; Díaz Espejo, Antonio; Fernández Torres, Rut; Pérez Romero, Luis Felipe; Hernández Santana, Virginia; Universidad de Sevilla. Departamento de Química Analítica; Universidad de Sevilla. Departamento de Agronomía; Ministerio de Ciencia e Innovación (MICIN). España
The presence of fruits provokes significant modifications in plant water relations and leaf gas exchange. The underlying processes driving these modifications are still uncertain and likely depend on the water deficit level. Our objective was to explain and track the modification of leaf-water relations by the presence of fruits and water deficit. With this aim, net photosynthesis rate (AN), stomatal conductance (gs), leaf osmotic potential (Ψπ), leaf soluble sugars and daily changes in a variable related to leaf turgor (leaf patch pressure) were measured in olive trees with and without fruits at the same time, under well-watered (WW) and water stress (WS) conditions. Leaf gas exchange was increased by the presence of fruits, this effect being observed mainly in WW trees, likely because under severe water stress, the dominant process is the response of the plant to the water stress and the presence of fruits has less impact on the leaf gas exchange. Ψπ was also higher for WW trees with fruits than for WW trees without fruits. Moreover, leaves from trees without fruits presented higher concentrations of soluble sugars and starch than leaves from trees with fruits for both WW and WS, these differences matching those found in Ψπ. Thus, the sugar accumulation would have had a dual effect because on one hand, it decreased Ψπ, and on the other hand, it would have downregulated AN, and finally gs in WW trees. Interestingly, the modification of Ψπ by the presence of fruits affected turgor in WW trees, the change in which can be identified with leaf turgor sensors. We conclude that plant water relationships and leaf gas exchange are modified by the presence of fruits through their effect on the export of sugars from leaves to fruits. The possibility of automatically identifying the onset of sugar demand by the fruit through the use of sensors, in addition to the water stress produced by soil water deficit and atmosphere drought, could be of great help for fruit orchard management in the future.
Design and implementation of an automated liquid-phase microextraction-chip system coupled on-line with high performance liquid chromatography
(Elsevier, 2014-03) Li, Bin; Petersen, Nickolaj Jacob; Ramos Payán, María Dolores; Hansen, Steen Honoré; Pedersen-Bjergaard, Stig; Universidad de Sevilla. Departamento de Química Analítica; Danish Council for Independent Research, Technology and Production Sciences
An automated liquid-phase microextraction (LPME) device in a chip format has been developed and coupled directly to high performance liquid chromatography (HPLC). A 10-port 2-position switching valve was used to hyphenate the LPME-chip with the HPLC autosampler, and to collect the extracted analytes, which then were delivered to the HPLC column. The LPME-chip-HPLC system was completely automated and controlled by the software of the HPLC instrument. The performance of this system was demonstrated with five alkaloids i.e. morphine, codeine, thebaine, papaverine, and noscapine as model analytes. The composition of the supported liquid membrane (SLM) and carrier was optimized in order to achieve reasonable extraction performance of all the five alkaloids. With 1-octanol as SLM solvent and with 25 mM sodium octanoate as anionic carrier, extraction recoveries for the different opium alkaloids ranged between 17% and 45%. The extraction provided high selectivity, and no interfering peaks in the chromatograms were observed when applied to human urine samples spiked with alkaloids. The detection limits using UV-detection were in the range of 1–21 ng/mL for the five opium alkaloids presented in water samples. The repeatability was within 5.0–10.8% (RSD). The membrane liquid in the LPME-chip was regenerated automatically between every third injection. With this procedure the liquid membrane in the LPME-chip was stable in 3–7 days depending on the complexity of sample solutions with continuous operation. With this LPME-chip-HPLC system, series of samples were automatically injected, extracted, separated, and detected without any operator interaction.
A simple and fast Double-Flow microfluidic device based liquid-phase microextraction (DF-µLPME) for the determination of parabens in water samples
(Elsevier, 2017-04-01) Ramos Payán, María Dolores; Maspoch, Santiago; Llobera, Andreu; Universidad de Sevilla. Departamento de Química Analítica
A fast double-flow microfluidic based liquid phase microextraction (DF-µLPME) combined with a HPLC-UV procedure using diode array detection has been developed for the determination of the four most widely used parabens: Ethyl 4-hydroxybenzoate (EtP), Propyl 4-hydroxybenzoate (PrP), Butyl 4-hydroxybenzoate (BuP) and IsoButyl 4-hydroxybenzoate (iBuP) in water samples. Parabens have successfully been determined in environmental (lake and river water) samples with excellent clean up, high extraction efficiency and good enrichment factor using double-flow conditions. The microfluidic device consists of two micro-channels, which contain the acceptor and sample solution separated by a flat membrane (support liquid membrane). The sample (0.32 mM HCl) and acceptor phase (5.6 mM NaOH) are delivered to the µLPME at 10 µL min−1 and 1 µL min−1 flow rate, respectively. The extraction efficiencies are over 84% for all compounds in water samples with enrichment factors within the range of 9–11 and recoveries over 80%. The procedure provides very low detection limits between 1.6 and 3.5 µg L−1. The extraction time and the volume required for the extraction are 5 min and 50 µL, respectively; which are greatly lower compared to any previous extraction procedure for parabens analysis. In addition, this miniaturized DF- µLPME procedure significantly reduces costs compared to not only the existing methods for paraben detection, but also to the existing analytical techniques for sample preparation.
An efficient microfluidic device based on electromembrane extraction for the simultaneous extraction of acidic and basic drugs
(Elsevier, 2021-05) Santigosa, Elia; Maspoch, Santiago; Muñoz, María; Ramos Payán, María Dolores; Universidad de Sevilla. Departamento de Química Analítica; Agencia de Gestió d’Ajusts Universitaris i the Recerca (GENCAT)
The simultaneous extraction of acidic and basic compounds is considered a great challenge. In this work, an efficient and fast microfluidic device is described for the simultaneous determination of acidic and basic drugs by two electromembrane extraction, offering extraction efficiencies over 98% for all analytes in human urine samples and solving the difficulties encountered to date. The sample is submitted into the device and the collected acceptor phase is directly analyzed by diode array detector and high-pressure liquid chromatography (HPLC). The device consisted of three poly(methylmethacrylate) layers and four electrodes to perform EME in two steps in a single device. Two acidic analytes (ketoprofen and naproxen) and two basic analytes (amitriptyline and loperamide) were selected as model analytes. The device proposed works under stable electric field conditions, low current intensities that confers great stability to the supported liquid membrane. After a comprehensive study of the SLM, 1:1 2-nitrophenyl octhyl ether:dodecanol was selected as optimal. This device has also been successfully applied in 1:2 diluted bovine plasma samples with recoveries over 84% and a relative standard deviation below 6%. This microfluidic device needs small sample volumes (lower than 50 μL) and offers short extraction times (10 min) and excellent clean-up. Furthermore, it has proven to be a robust and reproducible device after more than 30 consecutive extractions, and thanks to the low potential required (5 V), it allows its compatibility with a single battery.
An overview on the recent applications of agarose as a green biopolymer in micro-extraction-based sample preparation techniques
(Elsevier, 2021-03) Tabani, Hadi; Alexovič, Michal; Sabo, Ján; Ramos Payán, María Dolores; Universidad de Sevilla. Departamento de Química Analítica; Ministry of Education, Science, Research and Sport. Slovak Republic
Introducing a myriad array of chemicals in different industrial fields has made sample preparation inevitable for trace analysis. Classical extraction techniques such as solid phase extraction (SPE) and liquid-liquid extraction (LLE) techniques often suffer from tedious procedures (huge workload) and hazards to personnel and environment (samples and reagents are often user-unfriendly and processed in high amounts). For addressing these problems, microextraction techniques have been introduced. These systems benefit from using a minute amount of sample, reduced consumption of organic solvents, enhanced clean-up, high recovery and high enrichment factors. Moreover, approaches based on the use of natural materials have emerged during the last 10 years. Agarose is a natural biopolymer used as a green material in the form of gel-based separation medium. It has been recently utilized in the microextraction schemes. Easy fabrication, adjustability to get various dimensions and shapes, high inertness and biodegradability are of its main attributes. The present overview is focused on applications of agarose in solid phase microextraction (SPME), micro-solid phase extraction (μ-SPE) and liquid phase microextraction (LPME) – agarose film-liquid phase microextraction (AF-LPME) and gel electromembrane extraction (G-EME) since 2012. Besides, the pros and cons of agarose employment in the mentioned techniques will be described in depth.
Liquid phase microextraction integrated into a microchip device for the extraction of fluoroquinolones from urine samples
(Elsevier, 2019-03) Santigosa, Elia; Maspoch, Santiago; Ramos Payán, María Dolores; Universidad de Sevilla. Departamento de Química Analítica; Ministerio de Educación y Ciencia (MEC). España
For the first time, liquid phase microextraction miniaturized into a microfluidic chip device (μLPME) combined with a HPLC procedure using diode array (DAD) has been developed for the determination of four fluoroquinolones: marbofloxacin (MRB), norfloxacin (NRF), ciprofloxacin (CPR) and danofloxacin (DNF). The microfluidic chip consisted of two symmetrical channels which contained the acceptor and sample solution separated by a flat polypropylene membrane. Also, a comprehensive study was carried out in order to determine the importance of geometry optimization in microchips based liquid phase microextraction. The optimal channel size was 23 mm length, 3 mm width and 60 μm depth. Both solutions were delivered to the chip using two syringe pumps and the extract collected was directly analyzed by HPLC. The extractions were carried out under double-flow conditions and completed after 7 min. The procedure was successfully applied to urine samples obtaining recoveries within the range of 35 and 62% for all compounds and 10 μL sample consumption. This miniaturized μLPME-chip device significantly reduced the analysis time and the sample consumption compared to the existing sample preparation techniques for fluoroquinolones.
Green microfluidic liquid-phase microextraction of polar and non-polar acids from urine
(Springer, 2021-04) Santigosa, Elia; Pedersen-Bjergaard, Stig; Muñoz, María; Ramos Payán, María Dolores; Universidad de Sevilla. Departamento de Química Analítica; Agencia de Gestió d’Ajusts Universitaris i the Recerca (GENCAT)
In this work, hippuric acid (log P = 0.5), anthranilic acid (log P = 1.3), ketoprofen (log P = 3.6), and naproxen (log P = 3.0) were simultaneously extracted by a green microfluidic device based on the principles of liquid-phase microextraction (LPME). Different deep eutectic solvents (DESs) were investigated as supported liquid membrane (SLM), and a mixture of camphor and menthol as eutectic solvents in the molar ratio 1:1 was found to be highly efficient for the simultaneous extraction of non-polar and polar acidic drugs. LPME was conducted for 6 min per sample. Urine sample was delivered to the system at 1 μL min−1, and target analytes were extracted exhaustively (75–100% recovery) across the DES SLM, and into pure aqueous phosphate buffer pH 11.0 delivered as acceptor at 1 μL min−1. The acceptor was analyzed with liquid chromatography-UV detection. Interestingly, the DES enabled extraction of both the polar and non-polar model analytes at the same time; all chemicals were green and non-hazardous, and the chemical waste was less than 1 mg per sample.

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