A smartphone-based long optical path colorimetric turntable for selective determination of malachite green and investigation the specific adsorption behavior of the imprinted cavities within molecularly imprinted polymers

Imprinted cavities are the cornerstones for the recognition specificity of molecularly imprinted polymers (MIPs). But the investigations related to the recognition behavior of imprinted cavities within MIPs are scarce due to the inevitable non-specific adsorption on the outside surface of MIPs. Herein, we reported a differential strategy to investigate the pure specific adsorption into imprinted cavities within MIPs, demonstrated by using for malachite green (MG) as the model template. The adsorption isotherm and kinetics of MG into the imprinted cavities are determined by a differential colorimetry. A smartphone-based analytical device with rotating seven colorimetric tubes was fabricated to measure the absorbance on-line, monitoring simultaneously the amounts of MG adsorbed in six channels without terminating adsorption processes. The pure specific recognition by imprinted cavities within MIPs enhances the anti-interference ability and sensitivity for MG determination. The smartphone-based absorbance device with an optical path of 10 cm was applied to the field determination of MG in actual water samples, with the detection limit of 1.1 mu g L-1 and the recovery in the range of 94.1 similar to 105%. The difference in volume of eluent has little influence on absorbance measurement in the portable absorbance device.