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This paper addresses the evaluation of a new amphiphilic nanoparticle supported on silica and its application as sorbent in on-line solid phase extraction. The investigated sorbent material is a copolymer composed by [2- (Acryloyloxy) ethyl] trimethylammonium chloride (block A) and butyl acrylate (block B) prepared by reversible addition-fragmentation chain transfer. After polymerization the nanoparticles were adsorbed into silica surface by electrostatic attraction providing to the sorbent both, apolar and polar characteristics. After the fundamental studies to understand the main features of the synthesized nanoparticles supported on silica, this sorbent material was packed into an extraction column. This column was connected on line with liquid chromatography-tandem mass spectrometry and utilized for automated online determination of several analytes as Ochratoxin A, azoxystrobin, cyproconazole and difenoconazole, in wine and water samples.

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The fundamental relationships between the structure and chemistry of latex nanoparticles synthesized by reversible addition fragmentation chain transfer (RAFT) controlled living polymerization and their subsequent performance as pseudostationary phases (PSP) are reported in this paper. RAFT enables the rational optimization of latex nanoparticle pseudostationary phases and control of the behavior of the PSP. Nanoparticles comprised of amphiphilic diblock copolymers of 2-acrylamido-2-methylpropane sulfonic acid-derived ionic/hydrophilic blocks and butyl- ethyl- or methyl-acrylate-derived hydrophobic blocks were synthesized in two sizes. The mobility, methylene selectivity, and efficiency of each of the six pseudostationary phases are reported, as well as the relationship between monomer quantity and NP size. Linear solvation energy relationships are reported and compared to SDS micelles and previous nanoparticle pseudostationary phases. The solvation characteristics and selectivity of nanoparticle pseudostationary phases is shown to be affected primarily by the structure of the hydrophobic copolymer block. Butyl acrylate nanoparticles 17 nm in diameter are found to provide the best overall separation performance with over 500 thousand theoretical plates generated in 6 min separations.

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Capillary electrophoresis and electrokinetic chromatography are typically carried out in unmodified fused-silica capillaries under conditions that result in a strong negative zeta potential at the capillary wall and a robust cathodic electroosmotic flow. Modification of the capillary wall to reverse the zeta potential and mask silanol sites can improve separation performance by reducing or eliminating analyte adsorption, and is essential when conducting electrokinetic chromatography separations with cationic latex nanoparticle pseudo-stationary phases. Semipermanent modification of the capillary walls by coating with cationic polymers has proven to be facile and effective. In this study, poly([2-(acryloyloxy)ethyl]trimethylammonium chloride) polymers were synthesized by reversible addition-fragmentation chain transfer polymerization and used as physically adsorbed semipermanent coatings for capillary electrophoresis and electrokinetic chromatography separations. An initial synthesis of poly([2-(acryloyloxy)ethyl]trimethylammonium chloride) polymer coating produced strong and stable anodic electroosmotic flow of -5.7 to -5.4 × 10-4 cm2 /V⋅s over the pH range of 4-7. Significant differences in the magnitude of the electroosmotic flow and effectiveness were observed between synthetic batches, however. For electrokinetic chromatography separations, the best performing batches of poly([2-(acryloyloxy)ethyl]trimethylammonium chloride) polymer performed as well as the commercially available cationic polymer polyethyleneimine, whereas polydiallylammonium chloride and hexadimethrine bromide did not perform well.

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Electrokinetic chromatography (EKC) is a powerful analytical technique that uses an ionic pseudo-stationary phase (PSP) to separate neutral compounds. Although anionic surfactants are the most common choice for PSP, cationic latex nanoparticles are an attractive alternative. Reversible addition-fragmentation chain transfer (RAFT) polymerization was used to synthesize several types of diblock copolymers that self-assemble into latex nanoparticles, which were characterized by a variety of techniques including diffusion NMR. The performance of each nanoparticle as a PSP was studied by using a homologous series of ketones and linear solvation energy relationships (LSER) analysis. A cationic homopolymer coating was found to be necessary to prevent band broadening caused by analyte interactions with nanoparticles adsorbed to the capillary surface. No significant difference in methylene selectivity or LSER parameters was observed between nanoparticles with different cationic shells, but differences were observed between nanoparticles with different hydrophobic cores. Cationic latex nanoparticles behaved more like anionic latex nanoparticles than like cationic surfactants, suggesting that selectivity is primarily driven by the hydrophobic portion of a PSP. Cationic latex nanoparticles in combination with a homopolymer cationic capillary coating are an excellent choice for EKC analyses where an anodic electroosmotic flow is required.

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In recent years, researchers have begun to use corticosteroid metabolites in feathers (fCORT) as a metric of stress physiology in birds. However, there remain substantial questions about how to measure fCORT most accurately. Notably, small samples contain artificially high amounts of fCORT per millimetre of feather (the small sample artefact). Furthermore, it appears that fCORT is correlated with circulating plasma corticosterone only when levels are artificially elevated by the use of corticosterone implants. Here, we used several approaches to address current methodological issues with the measurement of fCORT. First, we verified that the small sample artefact exists across species and feather types. Second, we attempted to correct for this effect by increasing the amount of methanol relative to the amount of feather during extraction. We consistently detected more fCORT per millimetre or per milligram of feather in small samples than in large samples even when we adjusted methanol:feather concentrations. We also used high-performance liquid chromatography to identify hormone metabolites present in feathers and measured the reactivity of these metabolites against the most commonly used antibody for measuring fCORT. We verified that our antibody is mainly identifying corticosterone (CORT) in feathers, but other metabolites have significant cross-reactivity. Lastly, we measured faecal glucocorticoid metabolites in house sparrows and correlated these measurements with corticosteroid metabolites deposited in concurrently grown feathers; we found no correlation between faecal glucocorticoid metabolites and fCORT. We suggest that researchers should be cautious in their interpretation of fCORT in wild birds and should seek alternative validation methods to examine species-specific relationships between environmental challenges and fCORT.