Ultra performance liquid chromatography tandem mass spectrometry performance evaluation for analysis of antibiotics in natural waters

An ultra performance liquid chromatography electrospray tandem mass spectrometry (UPLC/MS/MS) method was developed and validated for the determination of 17 antibiotics in natural waters in one single extraction and chromatographic procedure. Gradient separation conditions were optimised for 17 compounds belonging to five different antibiotic groups: quinolones (oxolinic acid, nalidixic acid, pipemidic acid, flumequine), fluoroquinolones (enoxacin, ciprofloxacin, norfloxacin, ofloxacin, enrofloxacin, sarafloxacin, danofloxacin, difloxacin, lomefloxacin), sulphonamides (sulphamethoxazole, sulphamethazine), nitro-imidazole (ornidazole) and diaminopyrimidine (trimethoprim). The separation of all compounds, obtained using a 1.7 μm particle size column (100 mm?×?2.1 mm), was achieved within 10 min time. Water samples were adjusted to pH 7 and extracted using Oasis hydrophilic–lipophilic balance (HLB) solid phase extraction cartridges. After elution with methanol and concentration, extracts were injected in a C18 column (Acquity UPLC BEH C18) and detected by tandem mass spectrometry. Average recovery from 100 ng L^?1 fortified samples was higher than 70% for most of the compounds, with relative standard deviations below 20%. Performances of the method (recoveries, detection limit, quantification limit and relative standard deviation) and matrix effects were studied, and results obtained showed that method was suitable for routine analysis of antibiotics in surface water. Samples analysis from Seine River (France) confirmed the interest of antibiotic contamination evaluation in that area.

Enhanced electrostriction based on plasticized relaxor ferroelectric P(VDF‐TrFE‐CFE/CTFE) blends

The purpose of this work aims at enhancing the electrostrictive strain response and the mechanical energy density under moderate electric field, which is essential for actuator applications. For achieving this, plasticized effects as well as the influence of chlorofluoroethylene and chlorotrifluoroethylene defects on the electromechanical behavior of the copolymer matrix poly(vinylidene fluoride‐trifluoroethylene) (P(VDF‐TrFE)) are investigated. Experimental results showed that the plasticized terpolymer‐based CFE presented better electrical and mechanical performances than the CTFE one. Furthermore, such interesting properties exhibited superior advantages when CFE was combined with (DEHP) plasticizer, resulting in excellent electrostrictive strain response as well as mechanical energy density. Another aspect of this work reports on the influence of the composition, especially the CTFE content, on the electromechanical properties of the neat and plasticized P(VDF‐TrFE‐CTFE). This enables the determination of the desired terpolymer compositions for given applications, which are based on different criteria, such as crystallinity, elastic modulus, dielectric permittivity, and so forth. All the results demonstrated a possibility to realize high performance electroactive polymer actuators while achieving significant improved strain response and energy density under relatively low electric field. Such an investigation allows overcoming the current technological barrier of conventional electroactive polymers that suffer from the high applied electric field usually required to reach sufficient strain. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1368–1379     

Polymerization of water soluble cationic vinyl monomers

This paper summarizes investigations on the radical polymerization of cationic vinyl monomers with respect to the peculiarities of the reaction in aqueous solution, the synthesis of model polymers and polyelectrolytes with regular structure as well as to a new process of stabilized precipitation polymerization. The rate of polymerization depends on the ionic strength of the solution. Random copolymers of diallyldimethylammonium chloride and acrylamide with variable charge density but equal molecular weight were synthesized by a feeding technique. Block copolymers consisting of charged and uncharged monomelic units with different hydrophilicity are available using macroazoinitiators. The novel polymers are powerful stabilizers in the precipitation polymerization of water soluble cationic vinyl monomers in aqueous salt solution leading to a dispersion of fine polymer particles. Polyampholytes with alternating positively and negatively charged monomelic units in the backbone were obtained by cyclocopolymerization of diallylanmine compounds and derivatives of maleic acid.