Matrix‐assisted laser desorption/ionization mass spectrometry (MALDI MS) usually employs highly crystalline small‐molecule matrices, and the analyte is interpreted as being co‐crystallized with the matrix. We recently showed that semi‐crystalline polymers are efficient matrices for the detection of low‐molecular‐weight compounds (LMWCs) in MALDI MS and MALDI MS Imaging, and are dual‐mode, i. e., enabling both positive and negative modes. The matrix performances of two fluorene/napthalene diimide co‐polymers P(TNDIT‐Fl(C4C2)) and P(TNDIT‐Fl(C10C8)) were investigated and compared. Both are fully amorphous according to XRD measurements, show high relative absorption values at the wavelength of common MALDI lasers (λNd:YAG=355 nm: C4C2=73 %; C10C8=67 %), and are solution processable. As matrices, they are dual‐mode, and enable the detection of LMWCs while being mostly MALDI‐silent. Compared with semicrystalline polymer matrices, the amorphous matrices give similar or better signal intensities, thus indicating that analyte inclusion takes place in the amorphous part of the polymer matrix.
The cover feature shows that amorphous polymer inks allow the analysis of low‐molecular‐weight compounds in both positive and negative modes, even though MALDI matrices are traditionally highly crystalline. The amorphous polymers perform better than a related semicrystalline system, suggesting that analyte incorporation takes place in the amorphous phase and therefore significantly broadening matrix design rules. More details can be found in the Full Paper by F. Lissel and co‐workers on page 1338 in Issue 9, 2019 (DOI: 10.1002/cplu.201900203).
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