@article{MonakhovaSobolevaFedotovaetal.2022,
  author    = {Monakhova, Yulia and Soboleva, Polina M. and Fedotova, Elena S. and Musina, Kristina T. and Burmistrova, Natalia A.},
  title     = {Quantum chemical calculations of IR spectra of heparin disaccharide subunits},
  series = {Computational and Theoretical Chemistry},
  volume    = {1217},
  journal   = {Computational and Theoretical Chemistry},
  number    = {Article number: 113891},
  publisher = {Elsevier},
  address   = {New York, NY},
  isbn      = {2210-271X},
  doi       = {10.1016/j.comptc.2022.113891},
  year      = {2022},
  abstract  = {Heparin is a natural polysaccharide, which plays essential role in many biological processes. Alterations in building blocks can modify biological roles of commercial heparin products, due to significant changes in the conformation of the polymer chain. The variability structure of heparin leads to difficulty in quality control using different analytical methods, including infrared (IR) spectroscopy. In this paper molecular modelling of heparin disaccharide subunits was performed using quantum chemistry. The structural and spectral parameters of these disaccharides have been calculated using RHF/6-311G. In addition, over-sulphated chondroitin sulphate disaccharide was studied as one of the most widespread contaminants of heparin. Calculated IR spectra were analyzed with respect to specific structure parameters. IR spectroscopic fingerprint was found to be sensitive to substitution pattern of disaccharide subunits. Vibrational assignments of calculated spectra were correlated with experimental IR spectral bands of native heparin. Chemometrics was used to perform multivariate analysis of simulated spectral data.},
  language  = {en}
}
@article{BurgerLindnerRumpfetal.2022,
  author    = {Burger, Ren{\´e} and Lindner, Simon and Rumpf, Jessica and Do, Xuan Tung and Diehl, Bernd W.K. and Rehahn, Matthias and Monakhova, Yulia and Schulze, Margit},
  title     = {Benchtop versus high field NMR: Comparable performance found for the molecular weight determination of lignin},
  series = {Journal of Pharmaceutical and Biomedical Analysis},
  volume    = {212},
  journal   = {Journal of Pharmaceutical and Biomedical Analysis},
  number    = {Article number: 114649},
  publisher = {Elsevier},
  address   = {New York, NY},
  isbn      = {0731-7085},
  doi       = {10.1016/j.jpba.2022.114649},
  year      = {2022},
  abstract  = {Lignin is a promising renewable biopolymer being investigated worldwide as an environmentally benign substitute of fossil-based aromatic compounds, e.g. for the use as an excipient with antioxidant and antimicrobial properties in drug delivery or even as active compound. For its successful implementation into process streams, a quick, easy, and reliable method is needed for its molecular weight determination. Here we present a method using 1H spectra of benchtop as well as conventional NMR systems in combination with multivariate data analysis, to determine lignin's molecular weight (Mw and Mn) and polydispersity index (PDI). A set of 36 organosolv lignin samples (from Miscanthus x giganteus, Paulownia tomentosa and Silphium perfoliatum) was used for the calibration and cross validation, and 17 samples were used as external validation set. Validation errors between 5.6\% and 12.9\% were achieved for all parameters on all NMR devices (43, 60, 500 and 600 MHz). Surprisingly, no significant difference in the performance of the benchtop and high-field devices was found. This facilitates the application of this method for determining lignin's molecular weight in an industrial environment because of the low maintenance expenditure, small footprint, ruggedness, and low cost of permanent magnet benchtop NMR systems.},
  language  = {en}
}