A statistical design of experiments for optimizing the MALDI-TOF-MS sample preparation of polymers. An application in the assessment of the thermo-mechanical degradation mechanisms of poly (ethylene terephthalate)

[EN] The sample preparation procedure for MALDI-TOF MS of polymers is addressed in this study by the application of a statistical Design of Experiments (DoE). Industrial poly (ethylene terephthalate) (PET) was chosen as model polymer. Different experimental settings (levels) for matrixes, analyte/matrix proportions and concentrations of cationization agent were considered. The quality parameters used for the analysis were signal-to-noise ratio and resolution. A closer inspection of the statistical results provided the study not only with the best combination of factors for the MALDI sample preparation, but also with a better understanding of the influence of the different factors, individually or in combination, to the signal. The application of DoE for the improvement of the MALDI measure of PET stated that the best combination of factors and levels was the following: matrix (dithranol), proportion analyte/matrix/cationization agent (1/15/1, V/V/V), and concentration of cationization agent (2gL -1). In a second part, multiple processing by means of successive injection cycles was used to simulate the thermo-mechanical degradation effects on the oligomeric distribution of PET under mechanical recycling. The application of MALDI-TOF-MS showed that thermo-mechanical degradation primarily affected initially predominant cyclic species. Several degradation mechanisms were proposed, remarking intramolecular transesterification and hydrolysis. The ether links of the glycol unit in PET were shown to act as potential reaction sites, driving the main reactions of degradation. © 2011 Elsevier B.V.The authors would like to acknowledge the Spanish Ministry of Science and Innovation for the financial support through the Research Project UPOVCE-3E-013. The Spanish Ministry for Education is acknowledged for the concession of a predoctoral research position to J.D. Badia by means of the FPU program. Catalana de Polimers, S.A. and AIMPLAS are acknowledged for providing and processing the material, respectively. Royal Institute of Technology (KTH, Sweden) and Universitat Politecnica de Valencia (UPV, Spain) are also thanked for additional economical support.Badía Valiente, JD.; Strömberg, EM.; Ribes Greus, MD.; Karlsson, S. (2011). A statistical design of experiments for optimizing the MALDI-TOF-MS sample preparation of polymers. An application in the assessment of the thermo-mechanical degradation mechanisms of poly (ethylene terephthalate). ANALYTICA CHIMICA ACTA. 692(1):85-95. https://doi.org/10.1016/j.aca.2011.02.063S8595692