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Updated: Feb 23, 2026

Characterization of Biological Absorption Spectra Spanning the Visible to the Short-Wave Infrared
Published on: January 10, 2025
Molecular absorption measurements with an optical fibre coupled array of ultra-violet light-emitting diodes
Duy Anh Bui1, Karsten G Kraiczek2, Peter C Hauser1
1University of Basel, Department of Chemistry, Spitalstrasse 51, 4056 Basel, Switzerland.
Abstract:
A photometric detector based on eight different light-emitting diodes covering the ultraviolet range from 255 nm to 350 nm is described. These are coupled with fused silica optical fibres to a conventional cuvette with 1 cm optical path length or to a low volume flow through cell for detection in high-performance liquid chromatography. Photodiodes are employed for the measurement of the transmitted intensity as well as of a reference signal and the photocurrents are processed with a log-ratio amplifier to obtain a voltage proportional to absorbance values. The wavelength desired for the measurement at hand is selected by electronically switching on the requisite light-emitting diode. The detector was found to have a low noise level of 80 μAU. In batch-wise measurements as well as in detection for high-performance liquid chromatography dynamic ranges of 2-3 orders of magnitude were possible. Reproducibilities in peak areas for the latter application were better than 1%.
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