The determination of molar masses and their distributions is crucial in polymer synthesis and design. This work presents the current performance and limitations of diffusion-ordered spectroscopy (DOSY) on a low-field (benchtop) NMR spectrometer (at 90 MHz) as an alternative to size exclusion chromatography (SEC) for determining diffusion coefficient distributions (DCDs) and molar mass distributions (MMDs). After optimization for narrowly distributed homopolymers, MMDs obtained with inverse Laplace transformation (ILT) and log-normal distribution are compared with average molar masses obtained with mono- and bi-exponential fits, as well as MMDs obtained from SEC. This approach enables ILT to determine DCDs and MMDs even for bimodal homopolymers with fully spectrally overlapping signals and block copolymers with various chemical compositions, for which chemical composition profiles are determined. The feasibility of low-field diffusion NMR with samples dissolved in non-deuterated solvents is further demonstrated and methods for solvent suppression are discussed.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1002/marc.202400512 | DOI Listing |
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC11661663 | PMC |
Publication Analysis
Top Keywords
Similar Publications
Energy-Resolved Mass Spectrometry and Mid-Infrared Spectroscopy for Purity Assessment of a Synthetic Peptide Cyclised by Intramolecular Huisgen Click Chemistry.
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 PDFSuccess rate and factors affecting stability of infrazygomatic miniscrew implants: a systematic review and meta-analysis.
Eur J Orthod
December 2024
Department of Dentistry, All India Institute of Medical Sciences, Basni Industrial Area Phase-2, Jodhpur- 342005, Rajasthan, India.
Background: The infrazygomatic miniscrew implants (IZC-MSI) serve as innovative temporary anchorage devices placed parallel to the roots of molars in the infrazygomatic crest region, leveraging their extra-radicular location to support the en masse distalization and intrusion of the maxillary dentition. The efficacy and stability of these screws are crucial for their application in contemporary orthodontic practices.
Objectives: This systematic review aimed to estimate the success rate and factors affecting the stability of IZC-MSI.
Analysis of alkyl-anthraquinone derivatives from hydrogen peroxide industrial process, using LC × LC-HRMS with shifting gradients.
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.
View Article and Find Full Text PDFUrinary excretion profiles of the orexin receptor antagonist suvorexant and its metabolites.
Forensic Toxicol
December 2024
Forensic Science Laboratory, Osaka Prefectural Police Head Quarters, 1-3-18, Hommachi, Chuo-Ku, Osaka, 541-0053, Japan.
Purpose: Suvorexant is an orexin receptor antagonist used in the treatment of insomnia. In this study, we investigated the urinary excretion profiles of suvorexant and its major metabolites, including conjugates, to obtain fundamental information for proving exposure to suvorexant in criminal cases.
Methods: Urine specimens were collected from three subjects for maximum 168 h after a single oral ingestion of suvorexant (10 mg), and suvorexant and its metabolites in urine were determined using liquid chromatography-tandem mass spectrometry with a C18 semi-micro column.
Photomediated Cationic Ring-Opening Polymerization of Cyclosiloxanes with Temporal Control.
JACS Au
November 2024
School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, P. R. China.
Precision synthesis of polyorganosiloxanes and temporal control over the polymerization process during ring-opening polymerization (ROP) of cyclosiloxanes remain challenging due to the occurrence of side reactions, e.g., intramolecular transfer (backbiting) and intermolecular chain transfer, and irreversible catalyst transformation.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!