Development of a gel-based electrolyte for determination of heavy metals using smartphone

Abstract

Herein, a portable electrochemical device using biopolymeric gel-based electrolyte for the on-field simultaneous determination of Cd(II) and Pb(II) is presented. Pectin, a natural polymer, was used as a chemical delivery medium due to its biodegradation and fast-dissolving properties. Differential pulse voltammetry (DPV) was used to detect electrochemical signal of Cd(II) and Pb(II) solution dropped on the pectin-based electrolyte platform. The modification of screen-printed graphene electrode with Sb-Bi bimetallic alloy using both in situ and pre-mixed method was able to enhance the sensitivity of the sensor. The experimental results demonstrated that the developed gel-based electrolyte was capable of generating sharp and well-defined current signals, achieving the low detection limits of 50.98 ng mL-1 for Cd(II) and 40.80 ng mL-1 for Pb(II). The reproducibility, as indicated by the relative standard deviation was found to be less than 10.4% (n=10), when coupled with the NFC potentiostat. Lastly, the obtained sensor was utilized to analyze and quantify the two metals in various samples of cannabis-infused drinking water. The recoveries were obtained within the acceptable range of 80-110%. Moreover, the newly designed platform exhibited several advantages, such as, small sample volume (µL), low-cost, no sample preparation requirements, and biodegradability.