Biomedical subjects

L Coulier

Publications and source records attributed to L Coulier.

7 recordsLinked to original sources

PubMed2005

Comprehensive two-dimensional liquid chromatography and hyphenated liquid chromatography to study the degradation of poly(bisphenol A)carbonate.

Size exclusion chromatography (SEC), gradient polymer elution chromatography (GPEC) and liquid chromatography at critical conditions (LC-CC) have been developed and applied to observe chemical changes in poly(bisphenol A)carbonate (PC) due to hydrolytic degradation. Especially LC-CC appeared to be very successful to observe differences in functionality of PC as result of hydrolytic degradation. Observed differences due to degradation could be identified by (semi) on-line coupling to matrix assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The differences in functionality could be attributed to the formation of different end-groups, i.e. OH end-groups. In addition, comprehensive two-dimensional liquid chromatography (2D-LC) has been applied successfully to study the hydrolytic degradation of PC. LC-CC x SEC showed that the formation of PC with different end-groups occurred over the whole molecular mass range. This information could not be obtained with the separate liquid chromatographic techniques, thereby illustrating the added value of 2D-LC.

Benzhydryl Compounds↗

PubMed2005

Identification and quantification of (polymeric) hindered-amine light stabilizers in polymers using pyrolysis-gas chromatography-mass spectrometry and liquid chromatography-ultraviolet absorbance detection-evaporative light scattering detection.

Direct analysis of polymers containing polymeric hindered amine light stabilizers (HALS) by using pyrolysis coupled to GC-MS is applied successfully for fast and straightforward identification of these HALS additives. Each of the HALS additives shows different pyrolysis gas chromatograms containing characteristic pyrolysis products. As a result, HALS additives with very similar chemical structures, e.g. Chimassorb 944 and Chimassorb 2020, can be distinguished. A HPLC method with both ultraviolet (UV) and evaporative light scattering detection (ELSD) is developed to quantify the various HALS additives in extracts of polymers. The critical factor of the HPLC method is the use of a basic amine, like n-hexylamine, as a solvent additive to facilitate the elution of HALS additives. The various HALS additives can be distinguished according to retention time and peak shape and by using different detection methods. The suitability of the developed methods is demonstrated by the analytical performance of the HPLC method and the identification and determination of the actual content of HALS additives in polyolefines using pyrolysis GC-MS and HPLC. The HPLC method can also be used for the determination of the specific migration of HALS additives from food contact materials.

Amines↗

PubMed1994