A low-cost device for rapid 'color to concentration' quantification of cyanide in real samples using paper-based sensing chip

Highly selective azophenol-based chromogenic probe was synthesized that gave sharp color change in presence of cyanide. Based on colorimetric response of probe, a simple and economic colorimetric device has also been developed. Recently smartphones were employed for colorimetric analysis however there are number of limitations associated with it. Therefore, colorimeter was built using color sensor (TCS3200) and Arduino micro-controller for quantification of analytes using sensor coated paper chip. Initial colorimetric experiments revealed that sensor coated paper chip gave most linear response for change in the intensity of green component with change in the concentration of the cyanide. Thus, the device was calibrated using sensor coated paper chip and known concentrations of cyanide. It produced a best linear response over the range of 0 - 20 mu M concentration of cyanide with R-2 value of 0.9858 and limit of detection was calculated to be 0.86 mu M which is lesser than WHO's permissible limit of 1.9 mu M. Finally, the applicability of device was successfully evaluated for quantification of cyanide concentration in spiked river water and food samples. Thus, the device can be successfully calibrated and used for quantitative analysis of other hazardous analytes such as cyanide through colorimetric sensing chips.