Smartphone-based colourimetric detection of analytes after pre-concentration onto a hectorite clay-hydroxyethylcellulose hybrid

Abstract

Abstract This paper describes a new, smartphone-enabled quantitative analysis format, based on analyte pre-concentration by adsorption onto Bentone LT. Bentone LT pellet isolation comes after adsorption, followed by in-situ application of an analyte-selective chromogenic reaction. Resulting pellet colouration is captured by the phone’s integrated camera and assessed using the free open-source image processing software, ImageJ. Responses are calibrated and quantified. We here demonstrate the extended applicability of the proposed methodology for the smartphone-based quantification of specific model analytes. The smartphone-based assay is reliable in quantifying model analytes, alone or in mixture, from dilute aqueous solutions and depicts accurately the adsorption behaviour followed photometrically in solution. Its quantification capability was found to extend below that of the respective chromogenic reaction in solution. It is likely that the applicability of the proposed quantitative analysis format extends to other analytes where analyte-specific colour formation is feasible.