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Updated: Apr 9, 2026

Diffuse Reflectance Spectroscopy: Getting the Capillary Refill Test Under One's Thumb
Published on: December 2, 2017
Absorbance detector for capillary electrophoresis based on light-emitting diodes and photodiodes for the
1Department of Chemistry, University of Basel, Spitalstrasse 51, 4056 Basel, Switzerland.
Abstract:
A new absorbance detector for capillary electrophoresis featuring relatively high intensity light-emitting diodes as radiation sources and photodiodes for the deep-UV range was developed. The direct relationship of absorbance values and concentrations was obtained by emulating Lambert-Beer's law with the application of a beam splitter to obtain a reference signal and a log-ratio amplifier circuitry. The performance of the cell was investigated at 255 nm with the detection of sulfanilic, 4-nitrobenzoic, 4-hydroxybenzoic and 4-aminobenzoic acid and the indirect detection of acetate, propionate, butyrate and caproate using benzoate as the displacement dye molecule. Vanillic acid, L-tyrosine and DL-tryptophan as well as the sulfonamides sulfamerazine, sulfathiazole and sulfamethazine were determined at 280 nm. Good linearities over 3 orders of magnitude were obtained. The noise level recorded was as low as 50 μAU and the drift typically <200 μAU/5 min.
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