TY  - JOUR
A1  - Burger, René
A1  - Lindner, Simon
A1  - Rumpf, Jessica
A1  - Do, Xuan Tung
A1  - Diehl, Bernd W.K.
A1  - Rehahn, Matthias
A1  - Monakhova, Yulia
A1  - Schulze, Margit
T1  - Benchtop versus high field NMR: Comparable performance found for the molecular weight determination of lignin
JF  - Journal of Pharmaceutical and Biomedical Analysis
N2  - 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.
KW  - NMR
KW  - PLS-regression
KW  - Molecular weight determination
KW  - Chemometrics
KW  - Biomass
Y1  - 2022
SN  - 0731-7085
U6  - http://dx.doi.org/10.1016/j.jpba.2022.114649
VL  - 212
IS  - Article number: 114649
PB  - Elsevier
CY  - New York, NY
ER  - 
TY  - JOUR
A1  - Monakhova, Yulia
A1  - Soboleva, Polina M.
A1  - Fedotova, Elena S.
A1  - Musina, Kristina T.
A1  - Burmistrova, Natalia A.
T1  - Quantum chemical calculations of IR spectra of heparin disaccharide subunits
JF  - Computational and Theoretical Chemistry
N2  - 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.
KW  - IR spectroscopy
KW  - Chemometrics
KW  - Quantum chemistry
KW  - Molecular modelling
KW  - Quality control
Y1  - 2022
SN  - 2210-271X
U6  - http://dx.doi.org/10.1016/j.comptc.2022.113891
VL  - 1217
IS  - Article number: 113891
PB  - Elsevier
CY  - New York, NY
ER  -