Sökning: "mass spektrometri"
Visar resultat 1 - 5 av 14 avhandlingar innehållade orden mass spektrometri.
1. Aspects of Porous Graphitic Carbon as Packing Material in Capillary Liquid Chromatography
Sammanfattning : In this thesis, porous graphitic carbon (PGC) has been used as packing material in packed capillary liquid chromatography. The unique chromatographic properties of PGC has been studied in some detail and applied to different analytical challenges using both electrospray ionization-mass spectrometry (ESI-MS) and ultra violet (UV) absorbance detection. LÄS MER
2. Biokinetics and radiation dosimetry of 14C-labelled triolein, urea, glycocholic acid and xylose in man. Studies related to nuclear medicine “breath tests” using accelerator mass spectrometry
Sammanfattning : 14C-labelled substances have been used in biomedical research and clinical medicine for over 50 years. Physicians and scientists however, often hesitate to use these substances in patients and volunteers because the radiation dosimetry is unclear. LÄS MER
3. Improvement of the AMS-technique and applications to 3H and 59Ni Measurements
Sammanfattning : Accelerator mass spectrometry (AMS) is a highly sensitive technique for counting atoms. Its main advantage in comparison with radiometric methods is the smaller amount of sample required (by a factor of a thousand). The method has a high efficiency and requires only some ten mg of sample material. LÄS MER
4. Single fluid inclusion analysis using ToF-SIMS : Implications for ancient Earth biodiversiy and paleoenvironment studies
Sammanfattning : When and how life first emerged on the Earth is an area of intense research. Signs of the first life on Earth, including morphological fossils, are scarce and hard to interpret. An alternative approach is to study organic biomarkers, which are molecular fossils commonly considered as bona fide biosignatures. LÄS MER
5. Tuning the polylactide hydrolysis rate without introducing new migrants
Sammanfattning : The possibility to control and tune the hydrolytic degradation rate of polylactide without introducing any new degradation products was investigated by subjecting polylactide with cyclic or linear oligolactic acid additives, and a stereocomplex between the L- and D-enantiomers of polylactide to hydrolytic degradation at 37 and 60 °C for up to 39 weeks. The degradation was monitored by measuring mass loss, molar mass changes, water uptake, changes of surface structure, crystallinity and thermal properties. LÄS MER