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S. Kulka, B. Lendl, P Hinsmann, M. Kölhed, B. Karlberg, M. Vellekoop:
"ON-LINE FT-IR DETECTION IN CAPILLARY ZONE ELECTRO-PHORESIS (CZE) AND MICELLAR ELECTROKINETIC CHROMATOGRAPHY (MEKC)";
Poster: ICAVS II, Nottingham (UK); 19.08.2003 - 24.08.2003.

We present a reliable, universal approach for on-line FTIR spectrometric detection in capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC). We consider this approach to be superior to solvent elimination approaches in terms of analytical figures of merit (precision, sensitivity, linearity of calibration curve), its high degree of automation and finally due to its capability to handle also not volatile buffer systems.To achieve on-line mid-IR detection a micro-machined IR transparent flow cell has been developed and coupled to the separation system. The detection cell was constructed by two highly IR transparent CaF2 windows separated by an epoxy polymer layer and a titanium layer resulting in 150 µm broad and 2 mm long IR detection window with pathlengths ranging from 15 to 50 µm. The connections between the fused silica capillaries and the flow cell were accomplished by applying a small epoxy o-ring on the sharply cut ends of the capillary enabling an easy replacement in case of exchange of the capillary. The performance of the separation system (separation voltage, separation time, peak shape etc.) was tested with a separation of adenosine, guanosine and adenosine monophosphate and found to be barely influenced by the IR flow cell implemented in the capillary allowing for non-destructive molecule specific on-line FT-IR detection with a detection limit in the picogram range.Additionally the system was applied to a micellar electrokinetic chromatography (MEKC) separation comprising SDS as surfactant. Paracetamol, caffeine, p-nitrobenzyl alcohol, m-nitrophenol and p-nitrophenol were separated within 20 minutes with IR detection limits in the low nanogram range.