Gisela Guthausen

Publications (4)11.47 Total impact

• Article: Process and reaction monitoring by low-field NMR spectroscopy.

  Franz Dalitz, Markus Cudaj, Michael Maiwald, Gisela Guthausen
  Progress in Nuclear Magnetic Resonance Spectroscopy 01/2012; 60:52-70. · 5.21 Impact Factor
• Article: SEC-MR-NMR: online coupling of size exclusion chromatography and medium resolution NMR spectroscopy.

  Markus Cudaj, Gisela Guthausen, Thorsten Hofe, Manfred Wilhelm
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  ABSTRACT: Online coupling of size exclusion chromatography together with medium resolution nuclear magnetic resonance (SEC-MR-NMR) might be one solution to the problem of chemically sensitive detection in liquid polymer chromatography. By use of a combination of SEC with a table-top, specially designed 20 MHz NMR spectrometer, based on a permanent magnet, online (1) H NMR spectra of SEC fractions can be obtained. The integration of digital filters, mechanical shims and electronic shims led to substantially improved sensitivity and chemical selectivity compared to former TD (time domain) 20 MHz instruments. (1) H NMR spectra of PMMA and PS homopolymers as well as PS-PMMA block copolymers were of sufficient quality to enable detection and de-formulation of unknown polymer compounds. (1) H NMR spectra of acceptable resolution and S/N ratio were collected online during the chromatography. The SEC separation online with the NMR measurements performed well and resulted in the proof of principle of the SEC-MR-NMR combination.
  Macromolecular Rapid Communications 04/2011; 32(8):665-70. · 4.60 Impact Factor
• Article: Online Low-Field 1H NMR Spectroscopy: Monitoring of Emulsion Polymerization of Butyl Acrylate

  Maria A. Vargas, Markus Cudaj, Kidist Hailu, Kerstin Sachsenheimer, Gisela Guthausen
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  ABSTRACT: The emulsion polymerization of butyl acrylate was monitored by online nuclear magnetic resonance spectroscopy at 20 MHz 1H frequency. The reaction progress could be followed, monitoring the conversion of the reactant time-resolved without any need of sample preparation. Experimental data were analyzed with kinetic models for free-radical polymerization. The data comprised the polymerization rate in seeded batch emulsion polymerizations of butyl acrylate with doubly deionized water and D2O as solvent. The polymerization rate versus conversion curve behaves compatible with the three rate intervals model, typically observed in emulsion polymerizations. Zero−one kinetics explains the experimental results appropriately, leading to the determination of entry and termination rate coefficients.
  06/2010;
• Article: Investigation of hydrogenation of toluene to methylcyclohexane in a trickle bed reactor by low-field nuclear magnetic resonance spectroscopy.

  Gisela Guthausen, Agnes von Garnier, Rainer Reimert
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  ABSTRACT: Low-field nuclear magnetic resonance (NMR) spectroscopy is applied to study the hydrogenation of toluene in a lab-scale reactor. A conventional benchtop NMR system was modified to achieve chemical shift resolution. After an off-line validity check of the approach, the reaction product is analyzed on-line during the process, applying chemometric data processing. The conversion of toluene to methylcyclohexane is compared with off-line gas chromatographic analysis. Both classic analytical and chemometric data processing was applied. As the results, which are obtained within a few tens of seconds, are equivalent within the experimental accuracy of both methods, low-field NMR spectroscopy was shown to provide an analytical tool for reaction characterization and immediate feedback.
  Applied Spectroscopy 10/2009; 63(10):1121-7. · 1.66 Impact Factor