Determination of decabromodiphenyl ether in sediments using selective pressurized liquid extraction followed by GC–NCI-MS

A method based on selective pressurized liquid extraction (SPLE) followed by gas chromatography–negative ion chemical ionization-mass spectrometry (GC–NCI-MS) has been evaluated for analysis of decabromodiphenyl ether (PBDE-209) in sediment samples. Instrumental operating conditions such as source temperature and system pressure were optimized in the NCI-MS system, giving an instrumental detection limit of 2 pg. The limit of determination of the entire SPLE–GC–NCI-MS procedure was around 50 pg g^–1 dry weight (dw), with repeatability of replicates between 4 and 21% relative standard deviation. Application of the method to 13 different river and marine sediment samples collected in Spain revealed that levels of decabromodiphenyl ether ranged between 2 and 132 ng g^–1 dry weight.     

N.M.R. Spectra of the Fuchs0Nes: Structure of Naphthofuchsone

Following the initial synthesis of the fuchsones¹I, (α, η -diphenyl-1,4-benzoquinone methides), numerous substituted members of this series have been described by workers interested in triphenylmethane dyes. The fuchsones have been synthesized by the sulfuric acid condensation of benzilic acid and appropriate phenol¹, by dehydration of 4-hydroxytriphenylcarbinol², by oxidation 4-hydroxytri-phenylmethane and by photochemically induced reactions benzophenones with 2,6-dialkylphenols⁴.     

Simultaneous determination of hexabromocyclododecane, tetrabromobisphenol A, and related compounds in sewage sludge and sediment samples from Ebro River basin (Spain)

This paper describes the development of a methodology for the simultaneous determination and quantification of hexabromocyclododecane (HBCD), tetrabromobisphenol A (TBBPA), and related compounds (bisphenol A, monobromobisphenol A, dibromobisphenol A, and tribromobisphenol A) in sludge and sediment samples. The selected method is based on an extraction with dichloromethane: methanol followed by purification via SPE C₁₈ cartridges. Instrumental determination was carried out by liquid chromatography–quadrupole linear ion trap mass spectrometry (LC-QqLIT-MS), with quantification based on isotopic dilution method. Analyte recoveries were in the range of 39–120% and 88–126% for spiked sewage and sediment, respectively. Repeatability of replicate extractions was better than 13% relative standard deviation. Linearity was checked in the range of 0.05 and 25 injected nanograms. Limits of detection (LODs) and limits of quantification (LOQs) were in the range of 0.6 and 2.7 ng/g and 1.4 and 66 ng/g for sediment and sludge samples, respectively. The developed method was applied to sewage sludge and sediment samples collected along the Ebro River and Cinca River, one of its tributaries (northeast of Spain). TBBPA levels in sewage sludge ranged from not quantified to 1,329 ng/g dw, whereas levels in sediment samples were lower, between not detected and 15 ng/g dw. As regards HBCD, concentrations were between not detected and 375 ng/g for sludge samples and 0.8 and 1850 ng/g for sediments.     

Synthesis and Evaluation of GdIII‐Based Magnetic Resonance Contrast Agents for Molecular Imaging of Prostate‐Specific Membrane Antigen

Magnetic resonance (MR) imaging is advantageous because it concurrently provides anatomic, functional, and molecular information. MR molecular imaging can combine the high spatial resolution of this established clinical modality with molecular profiling in vivo. However, as a result of the intrinsically low sensitivity of MR imaging, high local concentrations of biological targets are required to generate discernable MR contrast. We hypothesize that the prostate‐specific membrane antigen (PSMA), an attractive target for imaging and therapy of prostate cancer, could serve as a suitable biomarker for MR‐based molecular imaging. We have synthesized three new high‐affinity, low‐molecular‐weight Gd^III‐based PSMA‐targeted contrast agents containing one to three Gd^III chelates per molecule. We evaluated the relaxometric properties of these agents in solution, in prostate cancer cells, and in an in vivo experimental model to demonstrate the feasibility of PSMA‐based MR molecular imaging.     

Determination of halogenated flame retardants by liquid chromatography coupled to mass spectrometry

We present an overview of current analytical methods for selected halogenated flame retardants (HFRs), focusing on instrumental determination using liquid chromatography coupled to mass spectrometry. We based the strategy for literature search on recent articles published in peer-reviewed scientific journals or conference proceedings. We report on selected HFRs and some metabolites and transformation products, and on the analytical performances of different ionization modes, with emphasis on selectivity and sensitivity. Moreover, we compare these parameters with those obtained by gas chromatography.     

Efficient palladium-catalyzed C-S cross-coupling reaction of benzo-2,1,3-thiadiazole at C-5-position: A potential class of AChE inhibitors

Functionalization of 2,1,3-benzothiadiazole (BTD) with thiols at C-5 position remains low explored. Moreover, the arylthiol-substitutions at this position are also unexplored and can not be found by a S_N2 or S_N1 reaction. In this sense, herein we present a new palladium-catalyzed methodology for a wide variety of unpublished 5-arylsulfanyl-benzo-2,1,3-thiadiazole derivatives synthesis with moderate to high yields using a low catalytic loading of Pd(L-Pro)₂ as low-coast, and efficient catalyst in low reaction time. Besides, we concluded that the pKa of thiol species has an important role in this catalysis, mainly in the CMD like catalytic cyclo process, which strongly interferes in the reaction yields. Furthermore, arylsulfanyl-benzo-2,1,3-thiadiazoles derivatives have been assessed (in vitro) as potential acetylcholinesterase inhibitors.     

Another potential shortcoming of AHP

In the last twenty years many features of Saaty’s Analytical Hierarchy Process (AHP) have been criticised, especially the additive hierarchical composition of conventional AHP, which leads to the possibility of occurrence of the Rank Reversal phenomenon (adding an irrelevant alternative may cause a reversal in the ranking at the top). In this paper we show another feature of AHP which may be, and in many application contexts will inneed be, an even stronger shortcoming of the method. It consists in the fact that the addition of indifferent criteria (for which all alternatives perform equally) causes a significant alteration of the aggregated priorities of alternatives, with important consequences. In hierarchies with four or more levels, rank reversal may happen. Since in almost all applications of AHP the set of criteria is not fixed ex-ante but is variable and is constructed in accordance with reasons of relevance and simplicity, almost all applications of AHP are potentially flawed.