A smartphone based quantitative point of care testing (POCT) system for simultaneous detection of multiple heavy metal ions
Abstract It is of great significance to develop versatile and cost effective point of care testing (POCT) systems for simultaneous quantitation of multiple analytes on site. This work reports on: 1) the customized electrodes which exhibit good analytical performance for simultaneous detection of Cd2+ Cu2+ Hg2+ Pb2+ with low detection limits (Cd2+ 0.296 mM; Cu2+ 0.055 mM; Hg2+ 0.351 mM; and Pb2+ 0.025 mM) and wide dynamic ranges (Cd2+ 0.50 12.5 mM; Cu2+ 0.10 9.50 mM; Hg2+ 0.50 12.5 mM; and Pb2+ 0.10 12.5 mM) using differential pulse voltammetry (DPV) measurements. 2) a hand held electrochemical analyzer which can realize two way communication with a smartphone and implement DPV measurements; its cost, weight and power consumption are $10.0, ~30 g and 253 mW, respectively; 3) a self developed APP DHMI which can control the analyzer, receive data from the analyzer, and plot the voltammograms on smartphone's screen in real time. This quantitative POCT system has been successfully demonstrated for simultaneous quantitation of Cd2+ Cu2+ Hg2+ Pb2+ in tap water, mineral water and Pearl River water, and the quantitation results correlated well with ICP MS measurements. The features of cost effectiveness, ease to use and reliability make this quantitative POCT system useful for on site monitoring of multiple heavy metal ions, especially in resource constrained environments.