Determination of cannabinoids in plasma using salting-out-assisted liquid–liquid extraction followed by LC–MS/MS analysis

The detection of the markers of Cannabis consumption in biological specimens is an important task for drug testing laboratories in varous contexts. A simple assay combining salting-out assisted liquid–liquid extraction sample preparation and LC–MS/MS analysis was applied to the measurement of Δ⁹-tetrahydrocannabinol, 11-nor-9-carboxy-Δ⁹-tetrahydrocannabinol (THC-COOH), 11-hydroxy-Δ⁹-tetrahydrocannabinol, cannabinol and cannabidiol concentrations in 100 μl plasma specimens. The assay had linearity of 1–100 ng ml⁻¹ for THC-COOH and 0.5–50 ng ml⁻¹ for the other tested cannabinoids. Assay validation criteria were fulfilled. Extraction yields (88.7–97.3%) and internal-standard correct matrix effects (−9.6 to +5.4%) were acceptable. The assay was applied to 238 clinical specimens from trauma patients, with 19 samples presenting quantifiable concentrations of at least one of the target compounds. The developed assay is a simple and efficient strategy for simultaneous measurement of Δ⁹-tetrahydrocannabinol, THC-COOH, 11-hydroxy-Δ⁹-tetrahydrocannabinol, cannabinol and cannabidiol concentrations in plasma specimens.     

Mercury(II) Binding to Metallothionein in Mytilus edulis revealed by High Energy-Resolution XANES Spectroscopy

Of all divalent metals, mercury (Hg^II) has the highest affinity for metallothioneins. Hg^II is considered to be enclosed in the α and β domains as tetrahedral α-type Hg₄Cys_11-12 and β-type Hg₃Cys₉ clusters similar to Cd^II and Zn^II. However, neither the four-fold coordination of Hg nor the existence of Hg–Hg atomic pairs have ever been demonstrated, and the Hg^II partitioning among the two protein domains is unknown. Using high energy-resolution XANES spectroscopy, MP2 geometry optimization, and biochemical analysis, evidence for the coexistence of two-coordinate Hg-thiolate complex and four-coordinate Hg-thiolate cluster with a metacinnabar-type (β-HgS) structure in the α domain of separate metallothionein molecules from blue mussel under in vivo exposure is provided. The findings suggest that the CXXC claw setting of thiolate donors, which only exists in the α domain, acts as a nucleation center for the polynuclear complex and that the five CXC motifs from this domain serve as the cluster-forming motifs. Oligomerization is driven by metallophilic Hg⋅⋅⋅Hg interactions. Our results provide clues as to why Hg has higher affinity for the α than the β domain. More generally, this work provides a foundation for understanding how metallothioneins mediate mercury detoxification in the cell under in vivo conditions.     

Synthesis and characterization of (pyrazolylethylphosphinite)nickel(II) complexes and catalytic activity towards ethylene oligomerization

Compounds (2‐(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)ethyldiphenylphosphinite ( L1 ), 2‐(3,5‐di‐tert‐butyl‐1H‐pyrazol‐1‐yl)ethyldiphenylphosphinite ( L2 ) , and 2‐(3,5‐diphenyl‐1H‐pyrazol‐1‐yl)ethyldiphenylphosphinite ( L3 ) were prepared using the synthetic routes reported in literature. These compounds were reacted with [NiCl₂(DME)₂] or [NiBr₂(DME)₂] under appropriate reaction conditions to afford six new nickel(II) compounds ([NiCl₂( L1)] ( 1 ), [NiCl₂( L2 )] ( 2 ), [NiCl₂( L3 )] ( 3 ), [NiBr₂( L1 )] ( 4 ), [NiBr₂( L2 )] ( 5 ) and [NiBr₂( L3 )] ( 6 )). The new nickel(II) pre‐catalysts catalyze the oligomerization of ethylene, in the presence of ethylaluminium dichloride as co‐catalyst, to produce butenes, hexenes, octenes and higher carbon chain ethylene oligomers with very little Friedel‐Crafts alkylation products when the reactions were run in toluene.     

Drop deformation in polymer blends during uniaxial elongational flow

The deformation in uniaxial elongational flow of dispersed droplets in immiscible molten polymer blends was studied for negligible interfacial tension and for viscosity ratio p = η(drop)/η(matrix) between 0.005 and 13, with an original method based on quenching elongated specimens. Although drop deformation (drop major axis over initial diameter) was in the range 1 < λ_d < 5, a good overall agreement was found with the small deformation Newtonian theory, which predicts that the drop versus matrix deformation ranges from 5/3 to 0 when p increases from 0 to infinity. The theoretical prediction that for p lower than 1, the droplet should deform more than the faraway surrounding matrix, with a limiting ratio of 5/3 at vanishing droplet viscosity, was experimentally verified.     

Phosphonic systems. Part 15. Addition of diethyl prop-2-enylphosphonate to aldehydes: Fragmentation vs. isomerization of kinetic products

Lithiated diethyl prop-2-enylphosphonate adds to an aliphatic or an aromatic aldehyde, yielding a diastereomeric mixture of the kinetically controlled α-adduct. Upon warming, these adducts decompose back to starting materials to give finally the thermodynamically controlled γ-adducts, or undergo fragmentation to diethyl phosphate and (E) dienes. The distribution of the first product between these two pathways is a function of the aldehyde (aromatic vs. aliphatic) and of steric interactions operating within the two diastereomers of the adduct.