Polymer HPLC MALDI

HPLC and the extensive complexity of ESI and MALDI spectra for multicomponent polymers with molar mass over about 10 g mol. Some applications of MALDI MS in polymer HPLC can be found for example in [300-303],... 

Liquid chromatography (LC) encompasses several techniques, which includes HPLC and SEC (sometimes referred to as GPC). Many variants of and developments from these techniques exist, and are used in the study and analysis of polymer degradation/oxidation. As discussed earlier, SEC is often coupled with MALDI-ToF-MS to facilitate the identification of the products of polymer degradation. SEC has also been coupled with mid-infrared detection and similarly used for studies of polymer degradation. SEC/GPC is discussed further below. 

Characterization of Silicon-Containing Polymers by Coupling of HPLC-Separation Methods with MALDI-TOF Mass Spectrometry... 

Rgure 3 SFC analysis with MALDI-MS of the main oligomers from Figure 1. (Reproduced with permission from Pasch H and Trathnigg B (1999) HPLC of Polymers. Berlin Springer Springer-Verlag.)... 

Most early efforts focused on the development of thin layer matrix precoated membranes, including those made of nylon and other synthetic polymers, nitrocellulose, anion- and cation-modified cellulose and regenerated cellulose. Several manufacturers currently offer 96-well plates with proprietary coatings for LC-MALDI-MS applications. This approach was described in more detail above. As mentioned previously, all of these sample preparation methods were originally developed for pre-purified samples or fractions, not for analytes eluting from an HPLC or capillary electrophoresis column. 

This technique coupled to HPLC has been used to determine the molecular weight of ter -octylphenol-ethoxylate surfactant polymers [235]. Schriemer and Li [236] used MALDI-MS to detect high molecular weight narrow polydisperse polymers up to 1.5 X 10 daltons. 

MALDI-MS has mainly been used as an off-line detector for various LC separation techniques (iso-cratic and gradient HPLC, LCCC, SEC) of polymers. The problems of coupling of LC and MALDI-ToFMS are related to the fact that MALDI-ToF is based on the pulsed desorption of molecules from a solid surface layer and, therefore, a priori not compatible with liquid chromatography. Different semion-line interfaces have been developed for automated LC sample collection and subsequent preparation of the samples for MALDI-ToF analysis. In... 

Thermal cross-linking of phenol polymers was also achieved by copolymerization of two different functional phenols. A copolymer of 4-hydroxyphenyl-N-maleimide (57, Scheme 12) and a furanosyl derivative (N-(4-hydroxy-phenyl)-2-furamide (64), Scheme 13) was subjected to irreversible cross-linking by thermally induced [4 + 2] cycloaddition (Diels-Alder cycloaddition). The copolymerization behavior of these two phenols was studied by following the monomer concentrations by HPLC, the increasing molecular weight by GPC, and the polymer composition by MALDI-TOF mass spectroscopy. It was found that the more electron rich and sterically less demand-... 

The cyclic undecamer (molecular mass 1244,8), present as the most abundant species in MALDI-TOF, has also been deteaed by Size Exclusion Chromatography (SEC) (Figure 24) as the maximum of a distinrt peak in the low-molar-mass region, well separated from the high polymer trace. HPLC analysis of the cyclic oligomer fraction up to the undecamer for another anionic PA6 sample not previously... 

Masci and co-workers [9] characterised block copolymers of N-isopropyl acrylamide with dimethyl acrylamide or 3-sulfopropyl methacrylate by HPLC, gel permeation chromatography (GPC) and MALDI-ToF-MS. Data are provided on the reaction conditions, kinetic data, M and polydispersities for the polymers and copolymers. 

Despite all of these advancements, there still exist several limitations in the synthesis of peptide-polymer conjugates. They include quantity, which is limited to the milligram scale, purification, and characterization. For example, conjugates incorporating hydrophobic polymers, such as polystyrene (PS), are especially difficult to purify and characterize by typical techniques, such as reversed-phase high-performance liquid chromatography (RP-HPLC) and matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF). 

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