Colorimetric sensor based on polymeric thin film for arsenic quantitation using colour response calibration

A simple, low‐cost and portable sensor for colorimetric determination of As(III) was developed. The sensing is carried out using a microcentrifuge tube as a mini‐reactor, where an Fe(III)‐1,10‐phenanthroline doped polyvinyl alcohol thin film is cast on the underside of the cap. Once Fe(III)‐1,10‐phenanthroline is reduced by arsine gas generated in situ from As(III), yielding the Fe(II)‐1,10‐phenanthroline complex, the red coloured product can be detected using colour analysis software. The As(III) content is then determined based upon the colour intensity of Fe(II)‐1,10‐phenanthroline on the film. Experimental conditions were optimised, and parameters affecting the complex formation and arsenic speciation were investigated. The method developed proved to be a selective colorimetric sensor for As(III). More significantly, the device could be directly used to detect As(III) in the field without any sample preparation requirements. The recovery for industrial wastewater and groundwater was found to be 97.5%‐104.0%. Hence, the thin film‐based test kit is easy to operate, portable and practical for the measurement of As(III) in the field.