The molecular level characterization of complex mixtures remains an analytical challenge. We have shown that the integration of complementary, high resolution, gas-phase separations allow for chemical formula level isomeric content description. In the current work, we revisited the current challenges associated with the analysis of dissolved organic matter using high resolution trapped ion mobility separation (TIMS) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). In particular, we evaluate the separation capabilities provided by TIMS-MS compared to MS alone, the use of ICR complementary data acquisition (DAQ) systems and transient processing strategies, ICR cell geometries (e.g., Infinity cell vs harmonized cell), magnetic field strengths (7 T vs 9.4 T vs 21 T) for the case of a Harney River DOM sample. Results showed that the external high-performance DAQ enables direct representation of mass spectra in the absorption mode FT (aFT), doubling the MS resolution compared to the default magnitude mode FT (mFT). Changes between half- vs full- apodization results in greater MS signal/noise vs superior MS resolving power (RP); in the case of DOM analysis, a 45% increase in assigned formulas is observed when employing the DAQ half (Kaiser-type) apodization window and aFT when compared to the default instrument mFT. Results showed the advantages of reprocessing 2D-TIMS-FT-ICR MS data with higher RP and magnetic field chemical formulae generated list acquired (e.g., 21 T led to a 24% increase in isomers reported) or the implementation of alternative strategies.
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This content will become publicly available on June 25, 2025
Diffusion Mapping with Diffractive Optical Elements for Periodically Patterned Photobleaching
Fourier transform-fluorescence recovery after photobleaching (FT-FRAP) using
a diffractive optical element (DOE) is shown to support distance-dependent diffusion analysis
in biologically relevant media. Integration of DOEs enables patterning of a dot array for parallel
acquisition of point-bleach FRAP measurements at multiple locations across the field of view.
In homogeneous media, the spatial harmonics of the dot array analyzed in the spatial Fourier
transform domain yield diffusion recovery curves evaluated over specific well-defined distances.
Relative distances for diffusive recovery in the spatial Fourier transform domain are directly
connected to the 2D (h,k) Miller indices of the corresponding lattice lines. The distribution of
the photobleach power across the entire field of view using a multidot array pattern greatly
increases the overall signal power in the spatial FT-domain for signal-to-noise improvements.
Derivations are presented for the mathematical underpinnings of FT-FRAP performed with 2D
periodicity in the photobleach patterns. Retrofitting of FT-FRAP into instrumentation for
high-throughput FRAP analysis (Formulatrix) supports automated analysis of robotically
prepared 96-well plates for precise quantification of molecular mobility. Figures of merit are evaluated for FT-FRAP in analysis for both slow diffusion of fluorescent dyes in glassy polymer matrices spanning several days and model proteins and monoclonal antibodies within aqueous solutions recovering in matters of seconds.
■ INTRODUCTION
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- PAR ID:
- 10522939
- Publisher / Repository:
- Analytical Chemistry
- Date Published:
- Journal Name:
- Analytical Chemistry
- Volume:
- 96
- Issue:
- 25
- ISSN:
- 0003-2700
- Page Range / eLocation ID:
- 10161 to 10169
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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