Simple and selective paper-based colorimetric sensor for determination of chloride ion in environmental samples using label-free silver nanoprisms.

Simple and selective paper-based colorimetric sensors using silver nanoprism (AgNPrs) were conveniently fabricated and developed for the determination of chloride ions (Cl) contaminated in the environment. Samples containing different concentrations of Cl were analyzed. The analysis is based on the oxidative etching of the AgNPrs into smaller silver nanospheres (AgNPss) by Cl. In the presence of Cl, the distinctive color change of the AgNPrs from dark-violet to red was rapidly visualized by the naked eye in 5min without the requirement of surface modification. For quantitative measurement using image processing, a good linear relationship (R = 0.996) between logarithmic of Cl concentration and the average mean color intensity was obtained in the range of 10-1000mgL with a detection limit of 1.3mgL. The developed sensors were investigated for precision, accuracy, and sensitivity and validated by the classical method. Statistical analysis proved that the developed sensors were precise, sensitive and accurate and can be used effectively for the analysis of Cl in natural waters.