Gold-coated nanostructured carbon tape for rapid electrochemical detection of cadmium in rice with in situ electrodeposition of bismuth in paper-based analytical devices

Herein we report a time and cost - effective approach for rapid determination of Cadmium (Cd) in rice based on electrochemical detection in paper-based analytical devices (PADs). Specifically, double sided conductive carbon tape coated with a thin layer of gold was used as the disposable electrochemical sensors for stripping analysis of Cd (II) coupled with in situ electrodeposition of bismuth. With the gold sputtering time of just 10 s the maximum electrochemical responses of Cd (II) could be obtained, suggesting that retained nanostructure of the carbon tape might facilitate the stripping analysis based on differential pulsed voltammetry. Under optimized experimental parameters, the concentration of Cd (II) from 2 to 150 μg L−1 could be linearly detected with the detection limit of 0.1 μg L−1. Because of the requirement of low sample volumes in PADs, more importantly, our approach could quantify Cd in rice samples with the weight of about two hundreds of milligrams, which could be treated using a muffle burner with the duration of around one hour. This study implied the practical potential of paper-based analytical devices in the field of rapid detection.