title: Determination of polyethylene glycol end group functionalities by combination of selective reactions and characterization by matrix assisted laser desorption/ionization time-of-flight mass spectrometry.
abstract: End groups play a critical role in macromolecular coupling reactions for building complex polymer architectures, yet their identity and purity can be difficult to ascertain using traditional analytical technique. Recent advances in mass spectrometry techniques have made matrix-assisted laser desorption/ionization time-of-fight (MALDI-TOF) mass spectrometry a rapid and powerful tool for providing detailed information about the identity and purity of homopolymer end groups. In this work, MALDI-TOF mass spectrometry was used to study end groups of linear polyethylene glycols. In particular, the identifications of alcohol, amine and thiol end groups are investigated because these nucleophilic moieties are among the most common within biological and synthetic macromolecules. Through comparative characterization of alcohol, amine, and thiol end groups, the exact identification of these end groups could be confirmed by selective and quantitative modification. The precision of this technique enables the unambiguous differentiation of primary amino groups relative to hydroxyl groups, which differ by only 1 mass unit. In addition, the quantitative conversion of various polyethylene glycol end groups using highly efficient coupling reactions such as the thiol-ene and azide-alkyne click reactions can be confirmed using MALDI-TOF mass spectrometry.
authors.affiliation: Tulane University, Department of Chemistry, <New Orleans, LA 70118, United States.
authors.forename: Boyu
authors.initials: B
authors.lastname: Zhang
authors.affiliation: Tulane University, Department of Chemistry, <New Orleans, LA 70118, United States.
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Tulane University, Department of Chemistry, <New Orleans, LA 70118, United States.
authors.forename: Brittany K
authors.initials: BK
authors.lastname: Myers
authors.affiliation: Tulane University, Department of Chemistry, <New Orleans, LA 70118, United States.
authors.forename: Ravinder
authors.initials: R
authors.lastname: Elupula
authors.affiliation: Tulane University, Department of Chemistry, <New Orleans, LA 70118, United States.
authors.forename: Janarthanan
authors.initials: J
authors.lastname: Jayawickramarajah
authors.affiliation: Tulane University, Department of Chemistry, <New Orleans, LA 70118, United States. Electronic address: sgrayson@tulane.edu.
authors.forename: Scott M
authors.initials: SM
authors.lastname: Grayson
mesh_terms: D015394:Molecular Structure; D011092:Polyethylene Glycols / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D011092:Polyethylene Glycols
keywords: Click chemistry; End group determination; Matrix-assisted laser desorption/ionization time-of-fight mass spectrometry; Polyethylene glycol; Polymer characterization