Betaine and Carnitine Derivatives as Herbicidal Ionic Liquids

This study focused on the synthesis and subsequent characterization of herbicidal ionic liquids based on betaine and carnitine, two derivatives of amino acids, which were used as cations. Four commonly used herbicides (2,4‐D, MCPA, MCPP and Dicamba) were used as anions in simple (single anion) and oligomeric (two anions) salts. The obtained salts were subjected to analyzes regarding physicochemical properties (density, viscosity, refractive index, thermal decomposition profiles and solubility) as well as evaluation of their herbicidal activity under greenhouse and field conditions, toxicity towards rats and biodegradability. The obtained results suggest that the synthesized herbicidal ionic liquids displayed low toxicity (classified as category 4 compounds) and showed similar or improved efficacy against weed compared to reference herbicides. The highest increase was observed during field trials for salts containing 2,4‐D as the anion, which also exhibited the highest biodegradability (>75 %).     

Improving the universal response of evaporative light scattering detection by mobile phase compensation

Mobile phase compensation, first reported for the charged aerosol detector (CAD), was used as a suitable method to overcome problems related to the mobile phase-dependent response of the evaporative light scattering detector (ELSD). Mobile phase compensation was effectively performed both in the flow injection- and in gradient modes. Without compensation, the response factors of the ELSD for six sulfonamide drugs differed by a factor of two when varying the mobile phase composition between 10 and 90% acetonitrile. This change could be effectively eliminated using the technique of mobile phase compensation, where a secondary pump with a reversed gradient was used to provide the detector with a constant composition of the mobile phase. For identical experimental conditions, the ELSD showed a nearly constant, albeit somewhat reduced, response with compensation. This indicates that under such conditions, the ELSD behaved as a concentration-sensitive detector. The analysis of sulfonamides drugs at 0.05% level using gradient UPLC-ELSD separation with mobile phase compensation is demonstrated.     

Determination of polydimethylsiloxane-air partition coefficients using headspace sorptive extraction

Polydimethylsiloxane-air partition coefficients (K(PDMS-A)) were determined using direct headspace analysis and headspace sorptive extraction (HSSE) with polydimethylsiloxane-coated (PDMS) stir bars. The partition coefficients were investigated for three compounds, p-dichlorobenzene (PDCB), naphthalene and camphor, all of which sublimate at room temperature and find use as moth repellents. In order to determine the K(PDMS-A) values of these compounds, the air concentration and the concentration present on PDMS, both at equilibrium, were measured. The results indicate that PDMS-air partition coefficients are proportional to octanol-air partition coefficients. Thus, the latter could be used to estimate the extraction efficiency of PDMS for these compounds in air. Alternatively, octanol-air partition coefficients for organic compounds could be estimated from the PDMS-air partition coefficient values. As expected, the PDMS-air (or octanol-air) partition coefficient increased with decreasing temperature. Importantly, the partition coefficients determined at saturated vapor pressures were lower than the values determined at lower analyte concentrations, with the differences being greater for compounds with larger partition coefficients. Consequently, caution should be exercised when applying K(PDMS-A) values determined at high analyte concentrations to measurements at lower concentrations, especially when the partition coefficients are large.     

Synthesis of block copolymers by atom transfer radical polymerization of tert‐butyl acrylate with poly(oxyethylene) macroinitiators

Poly(oxyethylene)s terminated at both ends with 2‐bromopropionate end‐groups were prepared and characterized by means of MALDI TOF mass spectrometry. It was shown, that atom transfer radical polymerization (ATRP) of methyl methacrylate with a poly(oxyethylene) macroinitiator in bulk proceeds with low initiation efficiency while polymerization of tert‐butyl acrylate proceeds with practically quantitative initiation, leading to ABA block copolymers. Originally formed tert‐butyl acrylate blocks contain terminal bromine, as expected for the ATRP mechanism. MALDI TOF analysis indicates, however, that in the later stages of polymerization side reactions lead to elimination of terminal bromine.     

Branched polyether with multiple primary hydroxyl groups: polymerization of 3-ethyl-3-hydroxymethyloxetane

Cationic polymerization of 3-ethyl-3-hydroxymethyloxetane gives branched, soluble macromolecules with multiple glycolic end groups. There are approximately 3–4 “normal” units per one branched unit.     

7-Substituted prostaglandin analogues. A new synthetic approach

Starting from methyl 7-oxo-7-(1-cyclopentene)-heptanoate, a simple synthesis of the methyl esters of 7-oxo- and 7-hydroxy-9,11-dideoxy-PGF ₁ as a model for 7-substituted prostaglandin analogues is described.

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7-Substituierte Prostaglandin-Analoge — ein neuer Syntheseweg

Zusammenfassung Ausgehend von Methyl-7-oxo-7-(1-cyclopenten)-heptanoat wird eine einfache Synthese der Methylester von 7-Oxo- und 7-Hydroxy-9,11-dideoxy-PGF ₁ als Modellverbindungen für 7-substituierte Prostaglandinanaloge beschrieben.

     

Empirical parameters of lewis acidity and basicity for aqueous binary solvent mixtures

Empirical parameters of Lewis acidity, E^N_T, introduced by Reichardt et al., and Lewis basicity, B_KT , introduced by Kamlet and Taft, have been determined for mixtures of water with ten organic solvents. In the case of water/alcohol mixtures a distinct dependence between these acidity and basicity parameters have been found. For the other solvent mixtures the E^N_T on B_KT dependence is more complex even if these parameters are purified from non-specific solute/solvent interactions.     

Correction to: Differences in the Efficiency of Separation of Analgesic Drugs by High-Performance Thin-Layer Chromatography with Similar Octadecyl Silica-Based Adsorbents

JPC – Journal of Planar Chromatography – Modern TLC -     

Photobleaching of melanosomes from retinal pigment epithelium: II. Effects on the response of living cells to photic stress

Melanosomes of the retinal pigment epithelium (RPE) are long lived organelles that may undergo photobleaching with aging, which can diminish the antioxidant efficiency of melanin. Here, isolated porcine RPE melanosomes were experimentally photobleached with visible light to simulate aging and compared with untreated granules or control particles (black latex beads) for their effects on the survival of photically stressed ARPE-19 cultures. Particles were delivered to cultures for uptake by phagocytosis then cells were exposed to violet light and analyzed by a new live cell imaging method to identify the time of apoptotic blebbing as a dynamic measure of reduced cell survival. Results indicated that untreated melanosomes did not decrease photic injury to ARPE-19 cells when compared with cells lacking particles or with cells containing control particles, as might be expected if melanin performed an antioxidant function. Instead cells with untreated melanosomes showed reduced survival indicated by an earlier onset of blebbing and a lower fraction of surviving cells after photic stress. Cell survival was reduced even further in stressed cells containing melanosomes that were photobleached, and survival decreased with increasing photobleaching time. Photobleaching of RPE melanosomes therefore makes cells containing them more sensitive to light-induced cytotoxicity. This observation raises the possibility that aged melanosomes increase RPE cell photic stress in situ, perhaps contributing to reduced tissue function and to degeneration of the adjacent retina that the RPE supports. How melanosomes (photobleached or not) interact with their local subcellular environment to modify RPE cell survival is poorly understood and is likely determined by the physicochemical state of the granule and its constituent melanin. The live cell imaging method introduced here, which permitted detection of a graded effect of photobleaching, provides a sensitive bioassay for probing the effects of melanosome modifications.