Automated DBS Extraction Prior to Hilic/RP LC–MS/MS Target Screening of Drugs

This article describes a rapid LC–MS/MS target screening method based on an automated extraction of 5 μL dried blood spots (DBS), two 5 min chromatographic runs on orthogonal phase columns (RP and Hilic) and a data dependent acquisition (DDA) of product ions spectra for the reliable identification of the detected compounds. The extraction step was performed in 2 min by using the LC autosampler itself in 96-well plates. This procedure was evaluated using 22 model compounds frequently encountered in forensic investigations, i.e., cocaine, benzodiazepines, amphetamines, opioids, antidepressants and antipsychotics. These investigations showed that even if the extraction step was reduced to a minimum, the extraction recoveries were satisfactory (median value of 40 %) and allowed for the detection of the model compounds in their therapeutic ranges, with the exception of morphine. Moreover, the use of two different chromatographic columns broadened the number of screening targets to those that behaved poorly under RP conditions, such as amphetamines or glucuronides, while keeping chromatographic gradients very short. This procedure was applied to 34 authentic post-mortem cases. It allowed the detection of 89 % of the compounds that were quantified in the routine procedures and the formal identification of 77 % of the compounds using their product ions spectra. These results were considered more than satisfactory compared to routine screening alone (GC–MS and LC-DAD, 55 % compound identification). The method described in this article is therefore a powerful approach for a fast, reliable and efficient target screening of drugs in forensic and clinical investigations.     

Influence of Equilibration Time in Solution on the Inclusion/Exclusion Topology Ratio of Host–Guest Complexes Probed by Ion Mobility and Collision‐Induced Dissociation

Host–guest complexes are formed by the creation of multiple noncovalent bonds between a large molecule (the host) and smaller molecule(s) or ion(s) (the guest(s)). Ion‐mobility separation coupled with mass spectrometry nowadays represents an ideal tool to assess whether the host–guest complexes, when transferred to the gas phase upon electrospray ionization, possess an exclusion or inclusion nature. Nevertheless, the influence of the solution conditions on the nature of the observed gas‐phase ions is often not considered. In the specific case of inclusion complexes, kinetic considerations must be taken into account beside thermodynamics; the guest ingression within the host cavity can be characterized by slow kinetics, which makes the complexation reaction kinetically driven on the timescale of the experiment. This is particularly the case for the cucurbituril family of macrocyclic host molecules. Herein, we selected para‐phenylenediamine and cucurbit[6]uril as a model system to demonstrate, by means of ion mobility and collision‐induced dissociation measurements, that the inclusion/exclusion topology ratio varies as a function of the equilibration time in solution prior to the electrospray process.     

Microwave‐assisted synthesis and characterization of biodegradable block copolyesters based on poly(3‐hydroxyalkanoate)s and poly(D,L‐lactide)

Microwave (MW)‐assisted ring‐opening polymerization (ROP) provides a rapid and straightforward method for engineering a wide array of well‐defined poly(3‐hydroxyalkanoate)‐b‐poly(D,L ‐lactide) (PHA‐b‐PLA) diblock copolymers. On MW irradiation, the bulk ROP of D,L ‐lactide (LA) could be efficiently triggered by a series of monohydroxylated PHA‐based macroinitiators previously produced via acid‐catalyzed methanolysis of corresponding native PHAs, thus affording diblock copolyesters with tunable compositions. The dependence of LA polymerization on temperature, macroinitiator structure, irradiation time, and [LA]₀/[PHA]₀ molar ratio was carefully investigated. It turned out that initiator efficiency values close to 1 associated with conversions ranging from 50 to 85% were obtained only after 5 min at 115 °C. A kinetic investigation of the MW‐assisted ROP of LA gave evidence of its “living”/controlled character under the experimental conditions selected. Structural analyses and thermal properties of biodegradable diblock copolyesters were also performed. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Gold-Catalyzed Regioselective Dimerization of Aliphatic Terminal Alkynes

A gold-catalyzed regioselective homodimerization of aliphatic terminal alkynes is described. Bulky and less Lewis acidic tBuXPhosAuNTf(2) is the preferred catalyst, and the additive, anhydrous NaOAc, substantially facilitates the reaction.     

Designing liquid-crystalline dendronised hexa-adducts of [60]fullerene via click chemistry

ABSTRACT

Liquid-crystalline [60]fullerodendrimers were constructed via click chemistry based on the reaction between hexa-adducts of [60]fullerene (C₆₀) bearing 12 azide groups and alkyne-terminated cyanobiphenyl dendrons of first- and second-generation. The structure of all the new compounds was confirmed by IR, UV, ¹H and ¹³C NMR spectroscopies and mass spectrometry. The mesomorphic properties were studied by polarised optical microscopy, differential scanning calorimetry and small-angle X-ray scattering. The hexa-adduct of C₆₀ functionalised with the first-generation dendrons gave rise to the formation of a smectic A phase and a rectangular columnar phase (c2mm symmetry) while the hexa-adduct of C₆₀ decorated with the second-generation dendrons displayed only a rectangular columnar phase (c2mm symmetry). Our results show that the hexa-adduct of C₆₀ is a unique synthetic platform for the design of fullerodendrimers and dendronised materials.     

Chemical reducing pedoenvironment in a peatland influenced by hematitic phyllite lithology in the southern Espinhaço chain,Brazil

A peatland in Pinheiro, Diamantina City, Minas Gerais State - Brazil, was sampled at different depths of two profiles with diverse vegetation coverings (grassland field and bush) in order to collect materials that might reflect changes in the chemical states of iron over the peat formation coming from original minerals such as hematitic phyllite surrounding the boggy pedon. Samples collected were chemically, structurally and magnetically characterized. The results show that both series of peats are composed of organic matter and minerals such as quartz, kaolinite, gibbsite, rutile and muscovite. Deeper layers present only quartz. Mössbauer spectroscopy shows that iron is present in both electron states, Fe²⁺ and Fe³⁺, under both vegetations, each valence appearing in the spectra in the form of a discrete doublet. No hyperfine magnetic splitting was observed in any spectrum at room temperature. The Mössbauer subspectral area of Fe²⁺ tended to increase from the upper to deeper layers. Magnetic measurements reveal that the magnetic response of the surface samples is the highest, displaying a sharp decrease below 15 cm and that the magnetic signal is a superposition of (super)paramagnetic and ferrimagnetic contributions. Samples from the grassland field also show a diamagnetic component for the deeper layers.     

Applicability of Microaerobic Technology to Enhance BTEX Removal from Contaminated Waters

As the addition of low concentrations of oxygen can favor the initial degradation of benzene, toluene, ethylbenzene, and xylenes (BTEX) compounds, this work verified the applicability of the microaerobic technology to enhance BTEX removal in an anaerobic bioreactor supplemented with high and low co-substrate (ethanol) concentrations. Additionally, structural alterations on the bioreactor microbiota were assessed throughout the experiment. The bioreactor was fed with a synthetic BTEX-contaminated water (~ 3 mg L^?1 of each compound) and operated at a hydraulic retention time of 48 h. The addition of low concentrations of oxygen (1.0 mL min^?1 of atmospheric air at 27 °C and 1 atm) assured high removal efficiencies (> 80%) for all compounds under microaerobic conditions. In fact, the applicability of this technology showed to be viable to enhance BTEX removal from contaminated waters, especially concerning benzene (with a 30% removal increase), which is a very recalcitrant compound under anaerobic conditions. However, high concentrations of ethanol adversely affected BTEX removal, especially benzene, under anaerobic and microaerobic conditions. Finally, although bacterial community richness decreased at low concentrations of ethanol, in general, the bioreactor microbiota could deal with the different operational conditions and preserved its functionality during the whole experiment.