New results on matrix‐assisted laser desorption/ionization mass spectrometry of widely polydisperse hydrosoluble polymers

Abstract

Polyvinylpyrrolidone (PVP) of molecular weight (M w ) 40 000 and 160 000 and polydispersity of 1.8± 2.2 was shown to yield matrix-assisted laser desorption/ionization (MALDI) mass spectra with the correct molar mass distribution of the polymer. This is a unique behavior among widely polydisperse samples and was ascribed to the capacity of PVP to complex the MALDI matrix. This result prompted us to test a new sample preparation technique consisting of flash-freezing followed by freeze-drying of the solution of the polymer with the matrix. In this paper we describe our preliminary results on MALDI-MS of polydisperse polymers obtained by this technique. This sample preparation method allowed us to obtain, for the first time, spectra yielding the true molecular weight distribution of polydisperse samples such as dextran, lichenan, nigeran, and poly(ethylene oxide).

Characterization of New Amphiphilic Block Copolymers of N‐Vinyl Pyrrolidone and Vinyl Acetate, 1 – Analysis of Copolymer Composition, End Groups, Molar Masses and Molar Mass Distributions

“…[17][18][19] Malvagna et al used DHB for the analysis of PVP. [20] IAA was also applied by Trimpin et al for the investigation of PVP. [21] Amphiphilic poly(VP-block-D,L-lactide) were successfully analysed by Luo et al using THAC.…”

Reflectron MALDI TOF and MALDI TOF/TOF mass spectrometry reveal novel structural details of native lipooligosaccharides

“…However, after the introduction of the delayed extraction technique and success of the dried‐drop preparation method, the value of skilled sample preparations has been increasingly underestimated. The classic dried‐drop method fails when the sample tends to aggregate because MM and polydispersity significantly increase, promoting matrix‐sample separation into two distinct phases and preventing co‐crystallization . Our strategy is the result of a combination of widely known MALDI sample preparation procedures aiming to place the appropriate matrix and LOS molecules into close contact.…”

“…The classic dried-drop method fails when the sample tends to aggregate because MM and polydispersity significantly increase, promoting matrix-sample separation into two distinct phases and preventing co-crystallization. [14] Our strategy is the result of a combination of widely known MALDI sample preparation procedures aiming to place the appropriate matrix and LOS molecules into close contact. Each preparation step plays a specific role: (i) dissolving LOS samples in a chelating ethylenediaminetetraacetic acid (EDTA) solution avoids aggregation due to the presence of divalent cations; (ii) mixing a few microliters of this EDTA solution with a small quantity of cationexchange resin converts phosphates and uronic salts into their acidic forms; (iii) spotting the final compound directly onto the MALDI plate in a matrix thin layer, composed of 2',4',6'trihydroxyacetophenone monohydrate (THAP) and nitrocellulose, captures salts and other impurities and also provides a nonconductive surface for LOS desorption/ionization.…”

A Perfect Couple: PLP/SEC/ESI‐MS for the Accurate Determination of Propagation Rate Coefficients in Free Radical Polymerization

“…[40,41] Some authors argue that in MALDI, sample preparation also has a major impact on mass discrimination. [42][43][44][45] In comparison to electrospray ionization, the mass bias in MALDI is somewhat reduced and ionization may be achieved for macromolecules with molecular weights of up to several hundreds of kg Á mol À1 depending on the monomer class. With the ionization process yielding mainly singly charged ions, an interpretation of the obtained mass spectrum in terms of a molecular weight distribution is possible after some data processing.…”