Ynze Mengerink

A new method to determine the blockiness and especially the block length distribution (BLD) of copolymers is described. This Systematic Workflow to Analyze Multi‐fragmented Polymers with Mass Spectrometry (SWAMP‐MS) is developed to characterize the sequence distribution of synthetic polymers. Copolymerization of polyamide 4,6 and polyamide 4,10 is used as a model system. Supercharged polymer ions, generated by electrospray ionization, swamp the mass spectrum due to different chemical related distributions (chain composition, end groups), the number of repeating units, the charge and adduct distribution, and isotopes distribution. Without selecting specific substrate ions, MSMS will transform this total ion‐SWAMP into chemical rich information of the polymer backbone. The generated fragments contain up to 20 monomers. The reduction of blockiness is evaluated by the decreasing abundancy of specific ions originating from the starting polymers. Moreover, evaluation of all significant fragments and applying Monte Carlo simulations can rebuild the polymer backbone and generate sequence distributions of the copolymerized samples, which is currently still a holy grail in co‐chemical polymer analysis.

In this study, we evaluate the use of various two-dimensional liquid chromatographic methods to characterize water-soluble, synthetically grafted bio-polymers, consisting of long poly(acrylic acid) chains and short maltodextrin grafts. The confirmation of the presence of grafting and the estimation of its extent is challenging. It is complicated by the limited solubility of polymers, their structural dispersity and chemical heterogeneity. Moreover, the starting materials (and other reagents, reaction products and additives) may be present in the product. Reversed-phase liquid chromatography (RPLC), hydrophilic-interaction liquid chromatography (HILIC) and size-exclusion chromatography (SEC) were used to characterize the product, as well as the starting materials. Additionally, fractions were collected for off-line characterization by infrared spectroscopy and mass spectrometry. The one-dimensional separation methods were found to be inconclusive regarding the grafting question. Breakthrough (the early elution of polymer fractions due to strong injection solvents) is shown to be a perpetual problem. This issue is not solved by comprehensive two-dimensional liquid chromatography (LC × LC), but information demonstrating the success of the grafting reaction could be obtained. SEC × RPLC and HILIC × RPLC separations are presented and discussed.

Background: DBS cards have been a big promise for decades. However, blood with low hematocrit (Ht) values results on regular cellulose-based DBS cards in larger spot sizes, compared with blood with high Ht-values. A new material has been developed to solve this problem. Results: This material, based on hydrophilic-coated woven polyester fibers, shows spot sizes independent of the Ht-value of blood. Homogeneity over the spot is within 10% RSD. Conclusion: Quantitative measurements over a broad Ht range show nonbiased results compared with whole spot analysis. The cards are experienced as reproducible, robust and easy to use on aspects of punchability and extractability.

Summary Liquid chromatography at critical conditions (LCCC) is being used more frequently, especially for the determination of cyclic structures in a matrix of the parent linear molecules, analyses that cannot be performed easily by other techniques. In practice, analyses are often more complex than separating the linear from the cyclic structures, e.g. in the determination of low concentrations of free (linear and cyclic) polyols like polytetrahydrofurane (pTHF) in functional polymers and coatings. To this end different chromatographic phase systems at the critical conditions for the polyols were investigated to obtain the maximum amount of information. The identification of different oligomeric series was performed by means of an on-line coupling of LCCC with atmospheric pressure chemical ionization – mass spectrometry (APCI-MS). Mass summated chromatograms were introduced to improve the signal to noise ratio of specific oligomeric series. MS cannot be used for quantitative purposes here; therefore the evaporative light scattering detector (ELSD) and the refractive index (RI) detectors were evaluated for routine analyses. Specific tailing problems observed with a drift tube in the ELSD are discussed. Two LCCC systems (reversed phase and normal phase) were compared for best selectivity