Molecular simulations of water/acetonitrile and water/methanol mobile phases in contact with a C(18) stationary phase were carried out to examine the molecular-level effects of mobile phase composition on structure and retention in reversed-phase liquid chromatography. The simulations indicate that increases in the fraction of organic modifier increase the amount of solvent penetration into the stationary phase and that this intercalated solvent increases chain alignment. This effect is slightly more apparent for acetonitrile containing solvents. The retention mechanism of alkane solutes showed contributions from both partitioning and adsorption. Despite changes in chain structure and solvation, the molecular mechanism of retention for alkane solutes was not affected by solvent composition. The mechanism of retention for alcohol solutes was primarily adsorption at the interface between the mobile and stationary phase, but there were also contributions from interactions with surface silanols. The interaction between the solute and surface silanols become very important at high concentrations of acetonitrile.
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http://dx.doi.org/10.1016/j.chroma.2011.02.012 | DOI Listing |
J Chromatogr A
December 2024
MAC-MOD Analytical, 103 Commons Ct, Chads Ford, PA 19317, USA.
ACS Omega
December 2024
Department of Chemistry, Humboldt Universität zu Berlin, Brook-Taylor-Str. 2, Berlin 12489, Germany.
In this study, we extended a previously developed one-pot double derivatization reaction to establish the first routine isotope-coded multiplex derivatization for vitamin D and its metabolites for application in clinical environments, using commercial reagents, without the need for specialized reagents and advanced synthesis requirements. The original derivatization process consisted of using both a Cookson-type reagent and derivatization of hydroxyl groups. Initially, the analytes are derivatized by a Diels-Alder reaction using 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD), followed by acetylation using acetic anhydride, catalyzed by 4-dimethylaminopyridine at room temperature.
View Article and Find Full Text PDFJ Sep Sci
January 2025
Department of Analytical, Bioanalytical Sciences and Miniaturization (LSABM) Chemistry, Biology and Innovation (CBI), UMR CNRS-ESPCI Paris 8231, ESPCI Paris, PSL University, CNRS, Paris, France.
Adduction on protein nucleophile sites by mustard agents can be monitored to assess detection of retrospective exposure to these agents. Cysteine 34 (Cys34) on human serum albumin was selected as the target of choice. This work targets di- and tripeptides adducted on Cys34 by sulfur mustard, sesquimustard, and nitrogen mustards separated in hydrophilic liquid chromatography (HILIC) and Reversed-Phase (RP) mode.
View Article and Find Full Text PDFSci Rep
December 2024
Department of Agri-Food Engineering and Environmental Management, Bialystok University of Technology, 15-351, Białystok, Poland.
The research used bacterial biosensors containing bacterial luciferase genes to monitor changes in the environment in real-time. In this work to express four different gene constructs: recA:luxCDABE, soxS:luxCDABE, micF:luxCDABE, and rpoB:luxCDABE in Escherichia coli SM lux biosensor after exposure to three different antibiotics (nalidixic acid, ampicillin, kanamycin) and diclofenac was determined. It was found that incubation of the E.
View Article and Find Full Text PDFSci Rep
December 2024
State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China.
Candida albicans is a common opportunistic pathogen, causing infections ranging from superficial to bloodstream infections. The limited antifungal options and rising drug resistance challenge clinical treatment. We screened 98 essential oils and identified 48 with antifungal activity against Candida albicans at 1% concentration, determining their minimum inhibitory concentrations (MIC).
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