Development, optimization and comparison of solid-liquid and liquid-liquid microextraction for the determination of four flavonols in Schinus molle L. using high-performance liquid chromatography coupled with second-order data modeling.

Flavonoids are particularly interesting because they have a broad spectrum of biological effects, including antioxidant and free radical scavenging activities. In this work, solid-liquid microextraction and dispersive liquid-liquid microextraction enhanced by ultrasound were developed and compared with the conventional method (Soxhlet extraction) to optimize the extraction of four flavonoids: rutin, quercitrin, quercetin, and myricetin in samples of Schinus molle (Aguaribay). During the development of the analytical method, different chemometric tools were used to optimize the microextraction procedure.

A novel strategy for the quantify of emerging isomeric pollutants belonging to the dihydroxybenzene family for environmental sample monitoring by amperometric detection.

This study introduces an innovative approach for quantifying isomeric pollutants utilizing an amperometric sensor. The determination of the isomers hydroquinone and catechol is based on the use of a glassy carbon electrode modified with Cu@PtPd/C nanoparticles (Cu@PtPd/C/GCE) in core-shell form, showing significant electrocatalytic activity in the oxidation of the later compounds. The determination was carried out at two different potentials: one at which where only hydroquinone is oxidized, and another in which where both hydroquinone and catechol are oxidized.

Removal of enrofloxacin using Eichhornia crassipes in microcosm wetlands.

The global consumption of antibiotics leads to their possible occurrence in the environment. In this context, nature-based solutions (NBS) can be used to sustainably manage and restore natural and modified ecosystems. In this work, we studied the efficiency of the NBS free-water surface wetlands (FWSWs) using Eichhornia crassipes in microcosm for enrofloxacin removal.

Development of an electrochemical sensor using carbon nanotubes and hydrophobic natural deep eutectic solvents for the detection of α-glucosidase activity in extracts of autochthonous medicinal plants.

The present work describes for the first time the use of a hydrophobic natural deep eutectic solvent (H-NADES) as a dispersant for carboxylated nanotubes for the design and construction of an electrochemical sensor for the assay of α-glucosidase and its inhibitors. In this work, we used as the electrochemical probe the product of the enzymatic reaction, which consists of two redox groups and generates the analytical signal. The combination of de carboxylic multi-walled carbon nanotubes (MWCNTc) and the H-NADES of thymol and lactic acid (TLa) increases the electroactive surface area and promotes electron transfer of the electrode modified with carbon nanotubes.

Highly sensitive and selective electrochemical sensor for simultaneous determination of gallic acid, theophylline and caffeine using poly(l-proline) decorated carbon nanotubes in biological and food samples.

In this work, a novel, simple and reproducible poly(l-proline)/functionalized multi-walled carbon nanotube composite on glassy carbon electrode (poly(PRO)-MWCNTs/GCE) was developed as an electrochemical sensor for the simultaneous determination of gallic acid (GA), theophylline (TP) and caffeine (CAF) by differential pulse voltammetry (DPV). The sensing platform was optimized by experimental design and response surface methodology, using various factors affecting polymerization and detection, such as electropolymerization time and potential, and pH, respectively. As a result, the dispersion conditions were the mixing of 1.

Binding the gap between experiments, statistics, and method comparison: A tutorial for computing limits of detection and quantification in univariate calibration for complex samples.

The present tutorial aims to review the most frequently reported criteria for the calculation of the limits of detection (LOD) and quantification (LOQ) in univariate calibration, summarizing their fundamentals, advantages, and limitations. The current criteria for estimating LOD and LOQ are based on diverse theoretical and/or empirical assumptions and require different amounts of experimental data, making the calculation rather complex in some cases. Moreover, alternative forms for calculating LOD/LOQ frequently lead to dissimilar results.

Natural deep eutectic solvent: A novelty alternative as multi-walled carbon nanotubes dispersing agent for the determination of paracetamol in urine.

This work reports for the first time the analytical performance of glassy carbon electrodes (GCE) modified with a dispersion of multi-wall carboxylated carbon nanotubes (MWCNTs-COOH) using a mixture of a natural deep eutectic solvent (NADES - LGH/lactic acid-glucose-water), ethylene glycol (EG) and water (GCE/MWCNT-LGH-EG) for the determination and N-(4-hydroxyphenyl) acetamide (paracetamol) (APAP) in urine samples. The optimization of both dispersion and measurement conditions was carried out using experimental design. The modified electrode exhibited enhanced current responses, demonstrating excellent electrochemical response towards APAP oxidation compared to MWCNTs-LGH, MWCNTs-EG, MWCNTs-HO-EtOH and MWCNTs-HO.

Determination of residual enrofloxacin in eggs due to long term administration to laying hens. Analysis of the consumer exposure assessment to egg derivatives.

The use of the antibiotic enrofloxacin (ENR) in poultry is controversial. A high-performance liquid chromatography coupled to fast-scanning fluorescence detection (HPLC-FSFD) method for the determination of ENR in egg white, egg yolk, and lyophilized samples was developed. In a first analysis, the long-term administration of ENR (100 days) to laying hens was carried out to determine its presence in egg white, yolk, or both.

Multivariate optimization of a dispersive liquid-liquid microextraction method for the determination of six antiparasite drugs in kennel effluent waters by using second-order chromatographic data.

Six veterinary active ingredients (imidacloprid, albendazole, fenbendazole, praziquantel, fipronil and permethrin) were extracted and quantified by liquid chromatography with diode array detection in water samples from a wetland system used for the treatment of waste from a dog breeding plant. Response surface methodology, based on least-squares and artificial neural networks modelling, was applied for the optimization of a dispersive liquid-liquid microextraction (DLLME) procedure. Firstly, two experimental designs were built for screening and optimization, respectively.

Dermal exposure to the UV filter benzophenone-3 during early pregnancy affects fetal growth and sex ratio of the progeny in mice.

The aim of this study was to analyze whether dermal exposure to benzophenone 3 (BP-3) during pregnancy affects critical parameters of pregnancy, and whether this exposure may affect the outcome of a second pregnancy in mice. Pregnant mice were exposed to 50-mg BP-3/kg body weight/day or olive oil (vehicle) from gestation day (gd) 0 to gd6 by dermal exposure. High-frequency ultrasound imaging was used to follow up fetal and placental growth in vivo.

Modelling of bioprocess non-linear fluorescence data for at-line prediction of etanercept based on artificial neural networks optimized by response surface methodology.

In the last years, regulatory agencies in biopharmaceutical industry have promoted the design and implementation of Process Analytical Technology (PAT), which aims to develop rapid and high-throughput strategies for real-time monitoring of bioprocesses key variables, in order to improve their quality control lines. In this context, spectroscopic techniques for data generation in combination with chemometrics represent alternative analytical methods for on-line critical process variables prediction. In this work, a novel multivariate calibration strategy for the at-line prediction of etanercept, a recombinant protein produced in a mammalian cells-based perfusion process, is presented.

Enhancement of multianalyte mass spectrometry detection through response surface optimization by least squares and artificial neural network modelling.

In this work, the use of design of experiments and posterior data modelling by artificial neural network (ANN) and least squares (LS) is presented as a suitable analytical tool for the performance optimization of a tandem mass spectrometric detector coupled to ultra-high performance liquid chromatography for the analysis of seventeen veterinary drugs. Firstly, a central composite design was built considering as factors the cone, capillary, extractor and radio frequency voltages of the mass spectrometer in order to obtain a proper combination to improve the sensitivity of the method. Secondly, a one factor design considering the collision voltage was built to define the adequate voltage for each daughter ion.

Occurrence, Distribution, and Ecological Risk of Fluoroquinolones in Rivers and Wastewaters.

The use of fluoroquinolones for the treatment of infections in humans and animals has increased in Argentina, and they can be found in large amounts in water bodies. The present study investigated the occurrence and associated ecological risk of 5 fluoroquinolones in rivers and farm wastewaters of San Luis, Santa Fe, Córdoba, Entre Ríos, and Buenos Aires provinces of Argentina by high-performance liquid chromatography coupled to fast-scanning fluorescence detection and ultra-high-performance liquid chromatography coupled to triple quadrupole mass spectrometry detection. The maximum concentrations of ciprofloxacin, enrofloxacin, ofloxacin, enoxacin, and difloxacin found in wastewater were 1.

Determination of six veterinary pharmaceuticals in egg by liquid chromatography: Chemometric optimization of a novel air assisted-dispersive liquid-liquid microextraction by solid floating organic drop.

Two extraction strategies for albendazole, chloramphenicol, trimethoprim, enrofloxacin, oxitetracycline and nicarbazin in egg were optimized for its quantitation by liquid chromatography. First, two designs were built to find out the optimized condition for the air assisted-dispersive liquid-liquid microextraction based on solidification of organic drop: a fractional factorial and a central composite design. The optimum conditions were 1140µL of water, 125mg of ZnSO, 1175µL of acetonitrile, 1200µL of methyl alcohol and 740µL of propanone, using 1.

Exploiting the synergistic effect of concurrent data signals: Low-level fusion of liquid chromatographic with dual detection data.

A low-level data fusion strategy was developed and implemented for data processing of second-order liquid chromatographic data with dual detection, i.e. absorbance and fluorescence monitoring.

Simultaneous multi-residue determination of twenty one veterinary drugs in poultry litter by modeling three-way liquid chromatography with fluorescence and absorption detection data.

A method for the simultaneous investigation of twenty one veterinary active ingredients in poultry litter based on MCR-ALS modeling of three-way liquid chromatography with fluorescence and UV detection data is presented. The chromatographic procedure was optimized in terms of both the nature of the organic solvent and the pH of the mobile phase to maximize the resolution of the analytes. In order to improve the simultaneous extraction efficiency of the twenty one veterinary drugs, a simplex-centroid design with combinations of the three components of the extracting mixture, i.

Ecotoxicity of veterinary enrofloxacin and ciprofloxacin antibiotics on anuran amphibian larvae.

The ecological risks posed by two β-diketone antibiotics (DKAs, enrofloxacin, ENR and ciprofloxacin, CPX), characterized by their long persistence in aqueous environments and known deleterious effect on model organisms such as zebrafish were analysed using Rhinella arenarum larvae. Sublethal tests were conducted using environmentally relevant concentrations of both ENR and CPX (1-1000μgL) under standard laboratory conditions for 96h. Biological endpoints and biomarkers evaluated were body size, shape, development and growth rates, and antioxidant enzymes (glutathione-S-transferase, GST; Catalase, CAT).

Dispersive liquid-liquid microextraction of quinolones in porcine blood: Validation of a CE method using univariate calibration or multivariate curve resolution-alternating least squares for overlapped peaks.

In the previously published part of this study, we detailed a novel strategy based on dispersive liquid-liquid microextraction to extract and preconcentrate nine fluoroquinolones in porcine blood. Moreover, we presented the optimized experimental conditions to obtain complete CE separation between target analytes. Consequently, this second part reports the validation of the developed method to determine flumenique, difloxacin, enrofloxacin, marbofloxacin, ofloxacin, ciprofloxacin, through univariate calibration, and enoxacin, danofloxacin, and gatifloxacin through multivariate curve resolution analysis.

Dispersive liquid-liquid microextraction of quinolones in porcine blood: Optimization of extraction procedure and CE separation using experimental design.

A dispersive liquid-liquid microextraction procedure was developed to extract nine fluoroquinolones in porcine blood, six of which were quantified using a univariate calibration method. Extraction parameters including type and volume of extraction and dispersive solvent and pH, were optimized using a full factorial and a central composite designs. The optimum extraction parameters were a mixture of 250 μL dichloromethane (extract solvent) and 1250 μL ACN (dispersive solvent) in 500 μL of porcine blood reached to pH 6.

Multiple responses optimization in the development of a headspace gas chromatography method for the determination of residual solvents in pharmaceuticals.

An efficient generic static headspace gas chromatography (HSGC) method was developed, optimized and validated for the routine determination of several residual solvents (RS) in drug substance, using a strategy with two sets of calibration. Dimethylsulfoxide (DMSO) was selected as the sample diluent and internal standards were used to minimize signal variations due to the preparative step. A gas chromatograph from Agilent Model 6890 equipped with flame ionization detector (FID) and a DB-624 (30 m×0.

Plasma retinoids concentration in Leptodactylus chaquensis (Amphibia: Leptodactylidae) from rice agroecosystems, Santa Fe province, Argentina.

Retinoids are known to regulate important processes such as differentiation, development, and embryogenesis of vertebrates: Alteration in endogenous retinoids concentration is linked with teratogenic effects. Retinol (ROH), retinoid acid (RA), and isoform 13-Cis-retinoic acid (13-Cis-RA), in plasma of a native adults frog, Leptodactylus chaquensis from a rice field (RF) and a forest (reference site; RS) were measured. ROH did not vary between treatment sites.

Rapid determination of retinoic acid and its main isomers in plasma by second-order high-performance liquid chromatography data modeling.

This paper reports the development of a method based on high-performance liquid chromatography (HPLC) coupled to second-order data modeling with multivariate curve resolution-alternating least-squares (MCR-ALS) for quantification of retinoic acid and its main isomers in plasma in only 5.5 min. The compounds retinoic acid (RA), 13-cis-retinoic acid, 9-cis-retinoic acid, and 9,13-di-cis-retinoic acid were partially separated by use of a Poroshell 120 EC-C18 (3.

Enhanced high-performance liquid chromatography method for the determination of retinoic acid in plasma. Development, optimization and validation.

When determining endogenous compounds in biological samples, the lack of blank or analyte-free matrix samples involves the use of alternative strategies for calibration and quantitation. This article deals with the development, optimization and validation of a high performance liquid chromatography method for the determination of retinoic acid in plasma, obtaining at the same time information about its isomers, taking into account the basal concentration of these endobiotica. An experimental design was used for the optimization of three variables: mobile phase composition, flow rate and column temperature through a central composite design.

Hybrid hard- and soft-modeling of spectrophotometric data for monitoring of ciprofloxacin and its main photodegradation products at different pH values.

A simple and fast on line spectrophotometric method combined with a hybrid hard-soft modeling multivariate curve resolution (HS-MCR) was proposed for the monitoring of photodegradation reaction of ciprofloxacin under UV radiation. The studied conditions attempt to emulate the effect of sunlight on these antibiotics that could be eventually present in the environment. The continuous flow system made it possible to study the ciprofloxacin degradation at different pH values almost at real time, avoiding errors that could arise from typical batch monitoring of the reaction.

A novel ion-pairing chromatographic method for the simultaneous determination of both nicarbazin components in feed additives: chemometric tools for improving the optimization and validation.

The development, optimization and validation of an ion-pairing high performance liquid chromatography method for the simultaneous determination of both nicarbazin (NIC) components: 4,4'-dinitrocarbanilide (DNC) and 2-hydroxy-4,6-dimethylpyrimidine (HDP) in bulk materials and feed additives are described. An experimental design was used for the optimization of the chromatographic system. Four variables, including mobile phase composition and oven temperature, were analyzed through a central composite design exploring their contribution to analyte separation.