Laser micro mass analysis of bulk polymeric samples

Abstract

Laser micro mass spectrometry (LAMMS) was used for organic micro-analysis of bulk polymeric samples with a lateral resolution of about 3 μm. The experiments were performed with a LAMMA 1000 instrument which was modified by the addition of a transmission illumination system for the observation of thin sections and a heating/cooling sample stage with sample transfer lock. It was found that crystallites or agglomerates of low-molecular-weight compounds could be identified by both molecular ions and characteristic fragments, and cyclic oligomers in bulkpolyamide 6 could be detected as cationized species if cations were present in the sample. On the other hand, the identification of high-molecular-weight polymers, e.g., in inclusions, was based on structurally significant fragments of the repeat unit. For samples with a low absorbance at the laser wavelength used, this fragment ion yield could be maximized by evaporating a thin absorbing layer onto the sample surface. If thin sections could be prepared from a sample a micro-FTIR analysis was possible. Such experiments gave results which were complementary to those of the corresponding LAMMS analysis.