title: In-source decay of hyperbranched polyesteramides in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.
abstract: Hyperbranched polyesteramides (DA2), prepared from hexahydrophthalic anhydride (D) and diisopropanolamine (A) have been characterized, by use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), field desorption (FD)-MS, and electrospray ionization (ESI)-MS. MALDI of polyesteramides produces protonated molecules. The spectra show a complex chemical composition distribution and end-group distribution which are mainly composed of two series of homologous oligomers DnA(n)+1 - mH2O and DnA(n) - mH2O, where m = 1-2. Signals from protonated molecules DnAn+1 and DnAn are almost absent in the MALDI spectrum, whereas these ions are responsible for the base peak of DnA(n)+1 - mH2O and DnA(n) - mH2O (m = 1-2) clusters in the ESI spectrum. The absence of -OH end-groups signals in the MALDI spectrum is due to a metastable decay of protonated DnA(n)+1 and DnAn ions in the ion source of the MALDI mass spectrometer prior to ion extraction. In-source decay results in the formation of protonated lower DnA(n)+1 - mH2O and DnA(n) - mH2O oligomers and their corresponding neutrals, leading to wrong conclusions concerning the relative end-group distribution as a function of the degree of polymerization and the chemical composition.
authors.affiliation: DSM Research, Geleen, The Netherlands.
authors.forename: D
authors.initials: D
authors.lastname: Muscat
authors.forename: H
authors.initials: H
authors.lastname: Henderickx
authors.forename: G
authors.initials: G
authors.lastname: Kwakkenbos
authors.forename: R
authors.initials: R
authors.lastname: van Benthem
authors.forename: C G
authors.initials: CG
authors.lastname: de Koster
authors.forename: R
authors.initials: R
authors.lastname: Fokkens
authors.forename: N M
authors.initials: NM
authors.lastname: Nibbering
mesh_terms: D007536:Isomerism; D013058:Mass Spectrometry; D008968:Molecular Conformation; D009757:Nylons / Q000737:chemistry*; D011091:Polyesters / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D009757:Nylons; D011091:Polyesters