Isolation of polychlorinated biphenyls by bonded normal phase liquid chromatography for environmental and biological monitoring

摘要

The presented licentiate thesis deals with the analysis of PCBs in lipid samples. By utilising high performance liquid chromatography the obligatory clean-up process can be performed with better efficiency, selectivity, accuracy, resolution and reproducibility than is achieved by the traditionally used open columns. In order to take full advantage of the possibilities of the HPLC clean-up procedure a number of stationary phases has been investigated regarding the retention of halogenated organic compounds, a study which also provides useful information in case of determining any of the other included compounds, such as PBDEs. The mechanisms governing retention in liquid chromatography continues to be a complex and not entirely explained phenomena. A strong inductive effect of chlorines bonded to aliphatic carbons that also are bonded to a hydrogen atom is demonstrated. The hydrogen obtains a weak acidic character which is critical for the retention. Attention has also been paid to polybrominated diphenyl ethers, a group of flame retardants structurally related to PCBs and of interest for future biological and environmental monitoring. The retention mechanisms of PBDEs was shown to be totally different on different stationary phases. While retention was increased with a higher degree of bromine substitution on some stationary phases the case was the reversed on others. The use of fractionation by bonded-phase HPLC of a real sample is demonstrated in the determination of some individual PCB congeners in blood and a pine needle epicuticular wax, an analysis that was not possible to perform with an acceptable resolution and accuracy with former methods. 28 refs, 16 figs, 8 tabs