3D-printed integrated device including functional paper components for direct Amitraz determination in beehive matrices

A 3D-printed electroanalytical device (3DD) designed to support the complete analysis of Amitraz (AMZ) is presented. AMZ is a broad-spectrum pesticide widely used to control Varroa destructor in bee colonies. It persists in the environment and in bee products, posing health risks. 3DD functions as a portable laboratory with multiple functional zones connected by microchannels. The device supports direct sampling, automates hydrolysis, and integrates electrochemical measurement. The 3DD body houses a functional rotary valve, into which the untreated sample is inserted. AMZ is converted to 2,4-dimethylaniline (2,4-DMA) via paper-mediated hydrolysis; 2,4-DMA is then flow-transported to the measuring chamber equipped with a paper sensor, where the aniline amine group is oxidized via differential pulse voltammetry (DPV). Disposable paper components enable device reuse. To achieve the required electroanalytical performance, several common and recycled paper substrates and various conductive inks were tested, demonstrating the effectiveness of the paper-mediated hydrolysis process. 3DD integrated AMZ analysis showed useful analytical performance, with a wide linear range (0.05–100 μM), a nanomolar limit of detection (LOD = 14 nM), and reproducibility (RSD ≤ 7%; n = 3). The exploitability of 3DD was demonstrated in both blanks and artificially contaminated honey and beeswax samples, yielding quantitative and reproducible recoveries (96%-112%; RSD ≤ 12%, n = 3). Summing up, we present a device for complete in situ analysis of AMZ. It encompasses all analytical steps, enabling pesticide determination within 5 min without sample pretreatment and highlighting the potential of combining additive manufacturing with functional paper components.