The aim of this study was to introduce a powerful coupling of Liquid Adsorption Chromatography (LAC) and Diffusion-Ordered Spectroscopy (DOSY) for comprehensive structure analysis. This new hyphenation approach facilitated the simultaneous separation of a polymer mixture and the determination of molar masses within a single 3D experiment. The online coupling of High-Performance Liquid Chromatography (HPLC) and two-dimensional DOSY-NMR will be called 3D-LAC-NMR-DOSY experiment. Our methodology enabled the chromatographic separation of analytes based on their chemical heterogeneity, and provided accurate molar masses of the analytes through 2D-DOSY. This new method was demonstrated on a polystyrene oligomer mixture. In this case, the oligostyrenes could be separated with LAC according to their tacticity and chain length in protonated acetonitrile as eluent and DOSY measurements provided the molar masses of each oligomer. In order to show the power of the 3D-LAC-NMR-DOSY method, the comparison to 2D-DOSY, 3D-DOSY and LAC-NMR was separately evaluated. Furthermore, the recently published solvent-independent molar mass calibration of diffusion coefficients was also successfully applied in our LAC-DOSY studies for molar mass predictions of the oligomers in acetonitrile. The predicted molar masses were in good agreement with the LAC-DOSY measurements and were verified by calibrations of diffusion coefficients and mass spectrometry. Finally, this pioneering 3D technique offers a powerful new tool for advancing structure analysis and enhancing our understanding of complex systems such as oligostyrenes.
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http://dx.doi.org/10.1016/j.chroma.2024.464750 | DOI Listing |
Nat Commun
January 2025
Ecole Polytechnique Fédérale de Lausanne (EPFL), Institute of Materials, Laboratory of Macromolecular and Organic Materials, Lausanne, Switzerland.
The plastic waste crisis is among humanity's most urgent challenges. However, widespread adoption of sustainable plastics is hindered by their often inadequate processing characteristics and performance. Here, we introduce a bio-inspired strategy for the modification of a representative high molar mass, biodegradable aliphatic polyester that helps overcome these limitations and remains effective at molar masses far greater than the entanglement molar mass.
View Article and Find Full Text PDFTurk J Orthod
December 2024
Government Dental College, Kozhikode, Faculty of Orthodontics and Dentofacial Orthopaedics, Kerala, India.
Objective: To investigate the effect of deferred timing of therapeutic extraction on the rate of space closure during en masse anterior retraction.
Methods: Twenty-six patients (aged 16-24 years) with bimaxillary protrusion, crowding <3 mm, requiring bilateral extraction of four first premolars were recruited. Permuted block randomization was done.
Methods Protoc
December 2024
Univ Brest, CEMCA, CNRS, UMR 6521, 29238 Brest, France.
Cyclic peptides have higher stability and better properties as therapeutic agents than their linear peptide analogues. Consequently, intramolecular click chemistry is becoming an increasingly popular method for the synthesis of cyclic peptides from their isomeric linear peptides. However, assessing the purity of these cyclic peptides by mass spectrometry is a significant challenge, as the linear and cyclic peptides have identical masses.
View Article and Find Full Text PDFEur J Orthod
December 2024
Department of Dentistry, All India Institute of Medical Sciences, Basni Industrial Area Phase-2, Jodhpur- 342005, Rajasthan, India.
Anal Methods
December 2024
Universite Claude Bernard Lyon 1, ISA UMR 5280, CNRS, 5 rue de la Doua, 69100 Villeurbanne, France.
The characterization of industrial working solutions containing numerous structurally related compounds and isomers requires the use of two-dimensional liquid chromatography coupled with high-resolution mass spectrometry (LC × LC-HRMS). The separation of alkyl-anthraquinone derivatives produced during hydrogen peroxide production was achieved by coupling a biphenyl and a C18 in the first and second dimensions, combined with the use of continuous shifting gradients in the second dimension (D). The use of shifting gradients offers a significant advantage over regular gradients, with a 20% increase in occupancy and better separation of isomers eluted within the same modulation.
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