Double-headed amphiphile-based sponge droplets: synthesis, characterization and potential for the extraction of compounds over a wide polarity range.

Supramolecular solvents (SUPRASs) are gaining momentum in the multi-residue analysis of liquid samples thanks to the delimited hydrophilic and hydrophobic microenvironments in their nanostructures. In this work, SUPRASs with increased hydrophilicity were synthesized with the aim of enhancing the extractability of polar compounds. For this purpose, a double-headed amphiphile, 1,2-decanediol, was self-assembled in hydro-organic media in the presence and absence of sodium chloride. The SUPRASs formed, characterized by scanning electron microscopy, consisted of sponge droplets made up of a highly convoluted three-dimensional (3D) network of amphiphile. The network contained interconnected bilayers that were intersected by similarly interconnected aqueous channels with high and nearly constant water content (∼30%, w/w). Both the inherently open structure of the sponge morphology and the increased hydrophilic-hydrophobic balance of the amphiphile, provided highly hydrophilic microenvironments into the aggregates that rendered in increased recovery factors for 15 perfluorinated compounds (PFCs, C4-C18, log Pow values from 0.4 to 11.6) in natural waters. Extraction took 15 min without further clean-up or evaporation of extracts which were readily compatible with LC-MS/MS quantitation. Absolute recoveries for PFCs, at the level of a few ng L-1, were in the range 70-120%, except for perfluoropentanoic acid (40%) and perfluorobutane sulfonic acid (51%). Detection limits for PFCs in water were in the range 0.01-0.02 ng L-1, which allowed their determination in slightly polluted waters (0.07-2.33 ng L-1). This work proves that hydrophilicity in SUPRASs can be tailored through the amphiphile and the morphology of their aggregates, and that this characteristic improves compound extractability in multi-residue analysis.

A new sample treatment strategy based on simultaneous supramolecular solvent and dispersive solid-phase extraction for the determination of ionophore coccidiostats in all legislated foodstuffs.

A single-step sample treatment, for the simultaneous extraction and clean-up for the determination of ionophore coccidiostats in EU legislated foodstuffs, is here proposed. The treatment is based on the combination of: (i) a supramolecular solvent with restricted access properties (SUPRAS-RAM), spontaneously formed by the addition of hexanol, water and THF to the sample; and (ii) dispersive solid phase extraction (dSPE). The SUPRAS-RAM extract was directly compatible with LC-MS/MS and no further re-extraction, evaporation or cleanup procedures were necessary. SUPRAS-RAM efficiently extracted the ionophores (recoveries in milk, eggs, fat, liver, kidney, and chicken and beef muscle were in the range 71-112%) and removed proteins and carbohydrates, whereas dSPE removed fats and other lipophilic compounds. The method was validated following the European Commission Decision 2002/657/EC. Detection limits (0.004-0.07 µg kg-1) were far below the maximum residue limits (1-150 µg kg-1). Method analytical and operational characteristics were suitable for routine determination of ionophores.

Patrones fenotípicos de susceptibilidad deStaphylococcus aureus de piel y partes blandas enhospitalizados

Introducción: los patrones fenotípicos de susceptibilidad de Staphylococcus aureusconstituyen la mejor expresión de su estudio fenotípico actualmente. Objetivo:identificar patrones fenotípicos de susceptibilidad ante cepas meticilina resistente ysensible. Método: se realizó una investigación transversal, descriptiva en el Hospital“Arnaldo Milián Castro” de 2013 a 2017 de Staphylococcus aureus aislados en piel ypartes blandas en pacientes hospitalizados que presentaron el antibiograma completoconsistente en: meticilina, ciprofloxacina, cloranfenicol, gentamicina y cotrimoxazol,clasificados en resistentes o sensibles; se crearon 16 patrones con los cuatro últimosantimicrobianos en ese orden preestablecido. La población fue de 1 789 aislamientos. Seobtuvo una frecuencia de distribución de cada patrón y se realizó el análisis estadísticoscomo Chi cuadrado de independencia y V de Cramer. Resultados: circularon los 16patrones fenotípicos de susceptibilidad, el 13, el 1 y el 15 fueron los de mayoresaislamientos en el quinquenio estudiado. Existió dependencia entre la susceptibilidad dela meticilina y los patrones 13 (RSSS), 1 (SSSS), 15 (RSRR), 16 (RSRS), 2(SSSR),9(RRRR) y 3 (SSRR); esta asociación fue moderada con los patrones 13 y 1, mientrasque fue baja con los cinco restantes. Siempre que se estuvo en presencia de meticilinasensible se encontraron, con mayor frecuencia, los patrones 1, 2 y 3 y si la meticilina eraresistente los patrones de mayor frecuencia fueron 13, 15, 16 y 9. Conclusiones: hubopleomorfismo de cepas de Staphylococcus aureus en infecciones de piel y partes blandascon predominio de asociación estadística a meticilina resistente.[AU]

A confirmatory method for the determination of phenolic endocrine disruptors in honey using restricted-access material-liquid chromatography-tandem mass spectrometry.

The present work describes the development and validation of an analytical method based on liquid chromatography (LC), coupled with tandem mass spectrometry (MS/MS) that allows the determination and confirmation of several endocrine-disrupting chemicals (EDCs) in honey. The EDCs studied were nine phenols of different nature: chlorophenols (2,4-dichlorophenol, 2,4,5-trichlorophenol, and pentachlorophenol), alkylphenols (4-tert-butylphenol, 4-tert-octylphenol, and 4-n-octylphenol) bisphenols (bisphenol-A and bisphenol-F), and 4-tert-butylbenzoic acid. The method incorporates a restricted-access material (RAM), coupled on-line to the LC-MS/MS system, which allows direct injection of the matrix into the RAM-LC-MS/MS system. The optimized method developed, RAM-LC-MS/MS, was applied to fortified honey samples, affording detection limits in the 0.6-7.2 ng g(-1) range, calculated for a signal-to-noise ratio of 3. In addition, the method was validated as a quantitative confirmatory method according to European Union Decision 2002/657/EC. The validation criteria evaluated were linearity, repeatability, reproducibility, recovery, decision limits, detection capabilities, specificity, and ruggedness. Repeatability and within-laboratory reproducibility were evaluated at two concentration levels, being +/-11% or below at 20 ng g(-1). The decision limits (CC(alpha)) and detection capabilities (CC(beta)) were in the 1.7-12.6 and 2.8-21.6 ng g(-1) range, respectively.

Development and validation of a method for the detection and confirmation of biomarkers of exposure in human urine by means of restricted access material-liquid chromatography-tandem mass spectrometry.

The present article describes the development and validation of a LC-MS/MS method for the determination and confirmation of biomarkers of exposure to different types of xenobiotics in human urine. The method combines the use of a restricted access material (RAM) coupled on-line to a LC-IT-MS system; in this way, a rapid and efficient matrix cleanup was achieved, reducing manual sample preparation to freezing and sample filtration. The ion trap (IT) mass spectrometry detector provided the selectivity, sensitivity and ruggedness needed for confirmatory purposes. The on-line RAM-LC-MS/MS method developed here has been validated as a quantitative confirmatory method according to the European Union (EU) Decision 2002/657/EC. The validation steps included the verification of linearity, repeatability, specificity, trueness/recovery, reproducibility, stability and ruggedness in fortified urine samples. Repeatability and within-laboratory reproducibility, measured as intraday and interday precisions, were evaluated at two concentration levels, being 12.7% or below at the concentration corresponding to the quantification limits. Matrix effects and non-targeted qualitative analyses were also evaluated in fortified urine samples. Decision limits (CC(alpha)) and detection capabilities (CC(beta)) were in the range of 3.6-16.5 and 6.0-28.1ngmL(-1) respectively. The results of the validation process revealed that the proposed method is suitable for reliable quantification and confirmation of biomarkers of exposure to xenobiotics in human urine at low ngmL(-1) levels. In addition, working in Data-Dependent Scan mode the proposed method can be used for the screening of these compounds in urine samples.

Fiber laser mode locked by a Sagnac interferometer with nonlinear polarization rotation.

We describe a new fiber laser configuration based on a nonlinear optical loop mirror with a symmetrical coupler, a quarter-wave retarder, and highly twisted, birefringent fiber in the loop. The nonlinear optical loop mirror configuration operates by nonlinear polarization rotation. We have achieved stable generation of subpicosecond pulses with milliwatts of average output power.