Approaches for characterizing unknown compounds by liquid chromatography in combination with mass spectrometry and nuclear magnetic resonance spectroscopy

Abstract

The stolen Scream painting of Edvard Munch was restored and in the restoration work of the damages on the painting, a glue of the materials which have to be somewhat identical to the glue that Munch used in the Scream painting was needed. A reference glue which was provided by the Munch museum and some origin materials from the Scream painting was analyzed in this thesis. The work presented characterized the two samples. The reference glue was analyzed by nuclear magnetic resonance spectroscopy (NMR) with protein options. A tryptic digestion procedure with DL-dithiothreitol (DTT) recduction and iodoacetamide (IAM) alkylation was explored in the study and the trypsination procedure was proved to function well in the method. The tryptic digested reference glue and the sample from the Scream were analyzed by liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS)(MS instruments: TOF-MS and IT-MS). The protein and peptide identifications by Mascot search engine were also applied and discussed showing the identification procedures’ pros and cons. The second part of this thesis, investigated some aspects for liquid chromatogray-solid phase extraction-nuclear magnetic resonance (LC-SPE-NMR) such as dimethyl sulfoxide (DMSO) as LC mobile phase, degassing effect on deuterium oxide (D2O) and deuterated acetonitrile (CD3CN) and an magnesium sulfate (MgSO4) column was packed and investigated to see whether it could absorb water. Results from the testing showed that the water peak was retained, which is a seldom trait in chromatography. Though not tested further, a MgSO4 column as a SPE column in the LC-SPE-NMR system was an idea which should be further.