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Updated: Jun 12, 2026

Colorimetric Paper-based Detection of Escherichia coli, Salmonella spp., and Listeria monocytogenes from Large Volumes of Agricultural Water
Published on: June 9, 2014
Water-based colourimetric optical indicators for the detection of carbon dioxide
Andrew Mills1, Graham A Skinner
1Department of Pure & Applied Chemistry, University of Strathclyde, Glasgow, UK G1 1XL. a.mills@strath.ac.uk
Abstract:
Water-based colourimetric indicator films are shown to have increased operational lifetimes under ambient conditions compared to similar solvent-based counterparts. The response and sensitivity characteristics of a water-based, carbon dioxide-responsive ink are characterised and compared and contrasted to those of a similar solvent-based indicator. The changes in the response characteristics of the ink as a function of the amount of base (sodium hydrogen carbonate) and plasticizer (glycerol) contained in the ink are reported, as are the effects of varying ambient temperature and humidity. The ink is incorporated into a felt tip pen and applied to a number of different substrates, producing a distinct, reversible colour change on all tested surfaces, when a sufficient level of carbon dioxide is present. The possible application of the indicator is discussed briefly.
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