Ion imprinted polymers integrated into a multi-functional microfluidic paper-based analytical device for trace cadmium detection in water

A novel multi-functional microfluidic paper-based analytical device (mu PAD) integrated with ion imprinted polymers (IIPs) was proposed for specific, portable and low-cost detection of cadmium (Cd(II)) in water. The IIP was grafted on paper and integrated into the mu PAD for separation of Cd(II) through multi-layer design. The paper-based screen printed carbon electrode (pSPCE) modified with reduced graphene oxide was fabricated and combined with the mu PAD for electrochemical sensing of the separated Cd(II). Reduced graphene oxide (rGO) was prepared via electroreduction on the working electrode surface of the pSPCE (rGO/pSPCE), which provided a sensitization effect with an improved signal for Cd(II) detection. The mu PAD developed with the integrated IIP and combined with rGO/pSPCE is able to detect Cd(II) with a linear range from 1 ng ml(-1) to 100 ng ml(-1) and a detection limit of 0.05 ng ml(-1). The accuracy of this mu PAD was evaluated with spiked real water samples and compared with that of the inductively coupled plasma mass spectrometry (ICP-MS) method, from which the recovery values ranged from 96.5% to 114.2% with RSDs <10% between the two methods. This mu PAD demonstrated its advantages of low-cost, portability, and suitability for highly sensitive detection of Cd(II), making it a valuable tool for on-site analysis.