A surface molecularly imprinted microfluidic paper based device with smartphone assisted colorimetric detection for butachlor in mung bean.

• Surface molecularly imprinted polymer with selective recognition capability to butachlor was fabricated. • A colorimetric paper chip combined with the smartphone was developed to detect butachlor in mung bean. • The sensor has highly selective and sensitive to butachlor with LOD is 1.43 ng/g. • The sensor is simple, cheap, portable and widely used for fast detection. A microfluidic paper chip colorimetric detection system based on surface molecular imprinting of zinc ferrite nanoparticles was established, and the detection images were obtained by smartphone for gray value analysis and determination of butachlor. The best functional monomers and addition ratio were selected by quantum chemical simulation calculation, the properties of the prepared molecularly imprinted polymers were analyzed, and the detection conditions were optimized. The linear range, sensitivity, and selectivity of the method were evaluated. The results showed that under the optimum conditions, the concentration of 2–80 ng/g had a good linear relationship (R2 is 0.9953), the detection limit was 1.43 ng/g, the specificity was good, and the whole detection process did not exceed 20 min. The microfluidic paper chip was applied to detect butachlor in mung bean samples. The results showed that the recovery was 93.4–106.4 %, and the relative standard deviation was less than 5.6 %. [ABSTRACT FROM AUTHOR]