Fluorescence and absorbance measurements for chromatographic analysis using a miniaturized micro-optical detection unit

We present a micro-optical detection unit for both laser induced fluorescence and absorbance analysis in fused silica capillaries., which can be used for chromatographic applications. The detection system is designed by means of non-sequential ray tracing simulations and prototyped by means of Deep Proton Writing. Such a prototyped master component is afterwards replicated by means of elastomeric moulding and vacuum casting. In a proof-of-concept demonstration the prototyped master micro-optical unit is used for the detection of various concentrations of coumarin dyes. The detection limit (SNR=3.3) achieved measures 0.6nM for fluorescence analysis and 12 mu M for absorbance measurements in capillaries with an inner diameter of 150 mu m. We discuss the optimization of different measurement parameters of the detectors in the setup in order to achieve accurate, fast and sensitive measurements.