Hyphenation of liquid chromatography and pyrolysis-flame ionization detection/mass spectrometry for polymer quantification and characterization

Size-exclusion chromatography (SEC) hyphenated to pyrolysis-gas chromatography (Py-GC) has been demonstrated as a powerful tool in polymer analysis. A main limitation to the wider application of the method are the long second-dimension Py-GC analysis times, resulting in limited first-dimension sampling and/or long overall run times. Therefore, we set out to develop an online hyphenated SECxPy-MS/FID method, removing the GC separation and allowing for a drastically reduced second-dimension analysis time compared to SEC-Py-GC. The pyrolysis method had a cycle time of 1.31 min, which was facilitated by liquid nitrogen cooling of the programmable temperature vaporizer (PTV) used for pyrolysis. The developed method featured no molar mass discrimination for masses above +/- 1.3 kDa, rendering it applicable to most commercial polymer systems. The method was demonstrated on multiple samples, including a complex industrial sample, yielding chemical composition heterogeneity and in some cases sequence heterogeneity information over the molar mass distribution.

Automated summary

Size-exclusion chromatography (SEC) coupled with pyrolysis-gas chromatography (Py-GC) is a powerful tool for polymer analysis. However, the long analysis times of the Py-GC step limit its wider application. Therefore, an online hyphenated SECxPy-MS/FID method was developed, removing the need for GC separation and significantly reducing the second-dimension analysis time compared to SEC-Py-GC. The developed method showed no molar mass discrimination for masses above +/- 1.3 kDa, making it applicable to most commercial polymer systems. Multiple samples, including a complex industrial sample, were successfully analyzed using this method, providing information on chemical composition heterogeneity and molar mass distribution.