Electric field enhanced sample preparation for synthetic polymer MALDI-TOF mass spectrometry via Induction Based Fluidics (IBF)

MALDI-TOF mass spectroscopy is used in the characterization of synthetic polymers. MALDI allows for determination of: modal, most probable peak (MP), molecular number average (MN), molecular weight average (MW), polydispersity (PD), and polymer spread (PSP). We evaluate a new sample preparation method using Induction Based Fluidics (IBF) to kinetically launch and direct nanoliter volumes to a target without contact. IBF offers signal improvement via field enhanced crystallization. This is the first paper to discuss filed enhanced crystallization in MALDI sample preparation. IBF can increase signal/noise (S/N) and signal intensity for polystyrene (PS), poly(methyl methacrylate) (PMMA), and poly(ethylene glycol) (PEG) across a mass range of 2500-92,000 Da showing more accurate PSP. Increases in S/N range up to: 279% for PS, 140% for PMMA, and 660% for PEG. Signal intensities increased up to: 438% for PS, 115% for PMMA, and 166% for PEG. Cross-polarization microscopy indicates dramatic morphology differences between IBF and micropipette. Finally, we speculate as to why IBF nanoliter depositions afford higher S/N values in experiments conducted in different instrumental configurations even without optimization.

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