Entwicklung nachweisstarker molekülspektrometrischer Detektionssysteme unter Verwendung von Diodenlasern für die Kapillarelektrophorese und verwandte Methoden

In this work two laser detection systems (photothermal and fluorimetric) were used for the detection in fused-silica capillaries and compared to commercialy available absorbtion spectrometric detection systems. The laser-induced fluorescene detection system was used for the indirect determination of non absorbing inorganic anions. 8-hydroxypyrene-3,6,8- trisulfonic acid (HPTS, as its trisodium salt) was used as background electrolyte. For the supression of the electroosmotic flow (EOF) the capillary was coated with linear acrylamide to accelerate the separation and improve the standard deviation of the migration time. The usage of HPTS as background electrolyte and a blue (452 nm) frequency-doubled diode laser with a quasi-cw optical output power of 10 µW for fluorescence-induction proved to be advantageous for the performance of the developed method. For the direct determination of non fluorescing compounds the near-field thermal lens effect was employed. The detector was realised by Dr. Faubel (Research Centre Karlsruhe) by using a frequency-doubled argon ion laser (emission wavelength, 257 nm) as the pump laser and a laser diode as the probe laser. The detector was characterised in detail and used for the determination of nitroaromatic compounds after separation by micellar electrokinetic chromatography. Comparing the performance of this detector to the performance of a commercialy available absorption spectrometric detector (at 257 nm) showed a substantial improvement in detection limits (up to 30-fold improvement) for the near-field thermal lens detector (NF-TLD). In adition to enviromental applications characterised near-field thermal lens detector was employed in the area of pharmaceutical analysis (therapeutical drug monitoring). The determination of cytostatics (etoposide, etoposide phosphate and teniposide) and antidepressants (fluoxetine and fluvoxamine) was chosen as suitable applications for NT-FL-detection. Using the NF-TLD device led to an improvement of detection limits by a factor of 35 to 60 for the determination of the cytostatics und by a factor of 28 to 670 for the determination of the antidepressants in comparison to a commercialy available absorption spectrometric detector working with a absorption wavelength of 257 nm.