Benchtop versus high field NMR: Comparable performance found for the molecular weight determination of lignin

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 implement...

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Bibliographic Details
Published in:Journal of pharmaceutical and biomedical analysis 2022-04, Vol.212, p.114649-114649, Article 114649
Main Authors: Burger, René, Lindner, Simon, Rumpf, Jessica, Do, Xuan Tung, Diehl, Bernd W.K., Rehahn, Matthias, Monakhova, Yulia B., Schulze, Margit
Format: Article
Language:English
Subjects:
Benchtop
Biomass
Chemometrics
Lignin
Lignin - chemistry
Magnetic Resonance Imaging
Magnetic Resonance Spectroscopy
Molecular Weight
Molecular weight determination
NMR
Organosolv
PLS-regression
Poaceae - chemistry
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Summary: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. •1H NMR spectroscopy (43 – 600 MHz) was used to model the molecular weight of lignin.•PLS regression models were developed and validated.•Equally good performance was achieved for benchtop and high-field devices.
ISSN:0731-7085
1873-264X
DOI:10.1016/j.jpba.2022.114649