J Chromatogr B Analyt Technol Biomed Life Sci
University Bonn, Institute of Forensic Medicine, Department of Forensic Toxicology, Stiftsplatz 12, 53111 Bonn, Germany. Electronic address:
Published: April 2017
Separation and identification of positional isomers is an important issue in forensic toxicology, particularly in the context of new psychoactive substances (NPS). Despite the structural similarity, positional isomers often show different pharmacological properties and thus can exhibit dramatic differences with respect to their toxicity. Additionally, besides these pharmacological and toxicological effects, the legal status is also of great importance. We present a sensitive and selective LC-MS/MS method to separate the ortho, meta and para isomers of methylmethcathinone (MMC) and methylethcathinone (MEC) using a core-shell biphenyl analytical column. Reliability of the method was confirmed under consideration of the validation parameters selectivity, linearity, accuracy and precision, analytical limits, processed sample stability, matrix effects and recovery. Linearity was demonstrated over the entire calibration range from 5 to 250ng/ml with the use of a 1/x weighting. Appropriate quantification and detection limits (LLOQ=5ng/ml, LOD<2ng/ml) could be achieved. Application of the method to real serum samples collected between June 2014 and August 2016 revealed the proof of a recent MMC or MEC consumption, respectively, in eight cases. Isomers of MMC could be detected in three of these eight cases, of which two were positive for 3-MMC and one was positive for 2-MMC. The other samples were tested positively for 3-MEC. In none of the samples 4-MMC, 2-MEC or 4-MEC could be detected. Only substances that were not governmentally controlled at that time could be detected, reflecting the rapid response of the recreational drug market to newly enacting drug laws.
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http://dx.doi.org/10.1016/j.jchromb.2017.01.046 | DOI Listing |
J Comput Chem
January 2025
Institute for Theoretical Chemistry, University of Stuttgart, Stuttgart, Germany.
We define an approximation to the internally contracted multireference coupled-cluster method with single and double excitations by a hybrid approach. The rationale is to treat the external pair energy contributions by the coupled-cluster method, which provides accurate results for a large part of the correlation energy while being tractable as the involved pair cluster operators commute. For the internal and semi-internal contributions, for which the coupled-cluster part becomes involved due to non-commuting operators, a linearized approach based on the coupled-electron pair approximation (CEPA) is used.
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January 2025
Frontiers Science Center for Transformative Molecules, School of Chemistry and Chemical Engineering, Zhangjiang Institute for Advanced Study, Shanghai Jiao Tong University, Shanghai, 200240, China.
In drug development, the substitution of benzene rings in aniline-based drug candidates with saturated bridged bicyclic ring systems often enhances pharmacokinetic properties while preserving biological activity. However, current efforts predominantly focuses on bicyclo[1.1.
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January 2025
Department of Orthopedic Surgery, Boston Medical Center, Boston, Massachusetts, USA.
Background: Anterior cruciate ligament (ACL) tears are frequent injuries in athletes that often require surgical reconstruction so that patients may return to their previous levels of performance. While existing data on patient-reported outcomes are similar between bone-patellar tendon-bone (BTB) and hamstring tendon (HT) autografts, the literature regarding return to sport (RTS), return to previous levels of sport activity, and graft failure rate remains limited.
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ACS Appl Mater Interfaces
January 2025
State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, China.
The comprehensive understanding of the effect of the chemical environment surrounding active sites on the pathway for the electrochemical carbon dioxide reduction reaction (eCORR) is essential for the development of advanced catalysts for large-scale applications. Based on a series of model catalysts engineered by the coordination of copper ions with various isomers of phenylenediamine [i.e.
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January 2025
Advanced Membranes and Porous Materials Center, Division of Physical Science and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia.
Understanding how structural modifications affect the photophysics of organic linkers is crucial for their integration into metal-organic frameworks (MOFs) for light-driven applications. This study explores the impact of varying the amine functional group position on two terephthalic acid derivatives─linker and linker ─by investigating their photophysics through a combination of steady-state and ultrafast laser spectroscopy and time-dependent density functional theory (TD-DFT) calculations. With tetrahydrofuran as the solvent, time-correlated single-photon counting revealed a 2-fold increase in the S excited-state lifetime of the molecule with the amine group at the meta position compared with that of the molecule with the amine group at the ortho position.
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