An efficient protocol to use iron oxide nanoparticles in microfluidic paper device for arsenic detection

This method describes a rapid ecofriendly and affordable method for detecting arsenic in the water sample. The system designed works on the principle that involves generation of arsine due to reduction of arsenic by bare and cysteine capped iron oxide nanoparticles and its further reaction with silver nitrate present on the microfluidic paper analytical device (μPAD). Change in the color of μPAD from colorless to reddish brown is a result of reaction between arsine gas and silver nitrate, and is the detection criteria. The sample solution of arsenic was prepared in lemon juice to provide the required acidic environment for hydride generation. This proposed method has detection limit of 0.01 ppm (10 ppb) and 1 ppm for cysteine capped and bare iron oxide nanoparticles respectively. This is for the first time that iron oxide nanoparticles are being used for detection and reduction arsenic species in environmental sample. The same device can be used for on-site detection in an ecofriendly manner.