Ambient characterization of synthetic fibers by laser ablation electrospray ionization mass spectrometry

Direct analysis of synthetic fibers under ambient
conditions is highly desired to identify the polymer, the finishes
applied and irregularities that may compromise its performance
and value. In this paper, laser ablation electrospray ionization
ion mobility time-of-flight mass spectrometry (LAESI-IMSTOF-
MS) was used for the analysis of synthetic polymers and
fibers. The key to this analysis was the absorption of laser light
by aliphatic and aromatic nitrogen functionalities in the
polymers. Analysis of polyamide (PA) 6, 46, 66, and 12 pellets
and PA 6, 66, polyaramid and M5 fibers yielded characteristic
fragment ions without any sample pretreatment, enabling their
unambiguous identification. Synthetic fibers are, in addition,
commonly covered with a surface layer for improved adhesion
and processing. The same setup, but operated in a transient infrared matrix-assisted laser desorption electrospray ionization (IRMALDESI)
mode, allowed the detailed characterization of the fiber finish layer and the underlying polymer. Differences in finish
layer distribution may cause variations in local properties of synthetic fibers. Here we also show the feasibility of mass
spectrometry imaging (MSI) of the distribution of a finish layer on the synthetic fiber and the successful detection of local surface
defects.