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Chromatographic retention times and mass spectrometral fragmentation of per- and polyfluoroalkyl substances (PFASs) standards were determined using the optimized parameters obtained for liquid chromatography with tandem high-resolution mass spectrometry (LC-HRMS) analysis. Characteristic fragment ions obtained at various collision energies (MS2 fragmentation) were used for structural elucidation to predict the identities of newly discovered (emerging) PFASs detected in environmental samples. Moreover, the COnductor-like Screening MOdel for Realistic Solvents (COSMO-RS) was used to calculate the octanol-water partition coefficients (Kow) and mean isotropic polarizabilities of known PFASs, and the values were plotted against their chromatographic retention factors (k) to obtain a multivariable regression model that can be used to predict k values of unknown PFASs. Retention factor values of different structural isomers of the unknown PFASs were calculated and compared to the experimental k. For all the unknown PFASs, the predicted k value for the isomer that matches the corresponding MS2 fragmentation was found to be within 5% of the experimentally measured k value. This study demonstrates the applicability of a simple approach that combines the use of computationally-derived log Kow and polarizabilities, experimentally-determined k values, together with observed MS2 fragmentation patterns, in assigning the structures of emerging PFASs at environmentally relevant conditions when no reference standards are available.
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Object classification in analytical chemistry via data‐driven discovery of partial differential equations
Glycans are one of the most widely investigated biomolecules, due to their roles in numerous vital biological processes. However, few system-independent, LC-MS/MS (liquid chromatography tandem mass spectrometry) based studies have been developed with this particular goal. Standard approaches generally rely on normalized retention times as well as m/z-mass to charge ratios of ion values. Due to these limitations, there is need for quantitative characterization methods which can be used independently of m/z values, thus utilizing only normalized retention times. As such, the primary goal of this article is to construct an LC-MS/MS based classification of the glycans derived from standard glycoproteins and human blood serum using a glucose unit index as the reference frame in the space of compound parameters. For the reference frame, we develop a closed-form analytic formula via the Green's function of a relevant convection-diffusion-absorption equation used to model composite material transport. The aforementioned equation is derived from an Einstein–Brownian motion paradigm, which provides a physical interpretation of the time-dependence at the point of observation for molecular transport in the experiment. The necessary coefficients are determined via a data-driven learning procedure. The methodology is presented in an abstractly and validated via comparison with experimental mass spectrometer data.
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- Award ID(s):
- 1903450
- PAR ID:
- 10229586
- Date Published:
- Journal Name:
- Computational and Mathematical Methods
- ISSN:
- 2577-7408
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1002/cmm4.1164
