Table of Contents:
Three formats of electromigrative separation techniques are used in this work: capillary electrophoresis (CE), micellar electrokinetic chromatography (MEKC) and isotachophoresis (ITP). The aim was the optimisation of sample injection and separation for the determination of forensically relevant analytes in complex samples. Instrumental aspects and the estimation of sensitivity and selectivity are taken into account.
The clandestine production of methylenedioxymethamphetamine (MDMA), an active ingredient of many Ecstasy tablets uses essential oils containing high amounts of safrole derived from different plants. Safrole as well as the structurally relates ingredients such as isosafrole, eugenol and anethol are hydrophobic neutral analytes. A profiling method via MEKC was developed for these essential oils. The optimisation of the composition of the separation electrolyte included the reduction of retention factors and the selectivity using buffer additives for high differences in the concentrations between main and minor constituents are present. Neutral surfactants were used for the dilution of samples. Essential oils used for the production of Ecstasy were analysed.
An optimisation scheme for the fast optimisation of the composition of separation electrolytes was developed using the retention data of homologous series. Characteristics of separation electrolytes are considered using four coefficients, the characteristics of analytes using one descriptor. The combination of both parameters allows a fast and efficient optimisation of separation problems.
The column-coupling ITP-CE with Laser induced fluorescence was used for the determination of the active ingredients of Ayahuasca, ITP-CE with electrospray ionisation was used for the determination of ergot alkaloids in ergot and herbal ecstasy. The ability of non-aqueous ITP for the separation of weak bases was examined.
Published on-line preconcentration techniques in capillary electrophoreses were examined in order to gain insight into the effects leading to analyte focusing. In addition, improved preconcentration techniques were developed. Methods were developed to compare on-line preconcentration techniques.