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Analytical Chemistry

Polymer Beads Improve Detection Limits Of Absorption Spectroscopy


Polystyrene beads suspended in samples increase optical path length and sample sensitivity

by Celia Henry Arnaud
January 12, 2015 | APPEARED IN VOLUME 93, ISSUE 2

In absorption spectroscopy, absorbance is directly proportional to the path length of the light through a sample containing analytes. In a new method called multiscattering-enhanced absorption spectroscopy, Christian Santschi, Volodymyr B. Koman, and Olivier J. F. Martin of ETH Lausanne report a low-cost, quick, and easy way to increase the path length through samples and thus improve the sensitivity of standard absorption spectroscopy. No instrument adaptations are required: The sample itself is modified (Anal. Chem. 2014, DOI: 10.1021/ac502267q). The researchers suspend polystyrene beads, which do not absorb visible light, in a cuvette with a sample containing the analytes. Light scattered by the beads traverses a longer path length that depends on the beads’ size and concentration. The researchers demonstrate that the method improves detection limits for various analytes, including 10-nm gold nanoparticles and some organic compounds, by a factor of roughly three to seven, respectively. The method is particularly well-suited to low analyte concentrations.

BEADS
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Compared with standard sample preparations (black arrows/spectrum), adding light-scattering beads increases the optical path length and analyte sensitivity in absorption spectroscopy (red arrows/spectrum).
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Comments
Jim Parsons (February 20, 2015 4:29 PM)
I really liked this article. Should prove to be very useful in the long run. Wonder how may polymer types can be adapter to this idea? And what sort of continuous phases are the best?

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