Integrated Sensing\nPlatform Validated for the Efficient\nand On-Site Screening of Amine-Containing Illicit Drugs

Efficient and reliable technologies for the on-site detection\nof\nillicit drugs are important in drug-facilitated crime investigations.\nHowever, the development of such technologies is challenging. Based\non the synthetic optimization, introducing a boron ester functional\ngroup to the two furanic indicators endows the stimulus-responsive\nproperties synergistically. The ring-opening reaction of the indicators\nin the presence of amine-containing illicit drugs generated well-known\ndonor–acceptor Stenhouse adducts, accompanied by strong color\nchanges. A small-size and lightweight laminated sensor was integrated\nbased on the outstanding ratiometric variations of the two active\nfuranic indicators. A prototype platform was fabricated equipped with\na circuit control, a mini pump, and a signal processing system. A\nuser-friendly detection and efficient screening of amine-containing\nillicit drugs, including phenethylamines, amphetamines, cathinones,\nand tryptamines in the liquid states were conducted. The ratiometric\nresponse of the sensor was linear in the concentration range of 2.1–10.6\nμg·mL<sup>–1</sup> for methamphetamine·HCl\nand methcathinone ·HCl. The detection limits for the two illicit\ndrugs at the sublevel (ng·mL<sup>–1</sup>) were found\nto be 8.4 and 9.0 ng·mL<sup>–1</sup>, respectively. Double-blind\nfield tests and different illicit drugs were evaluated with good screening\ncapability. Successful trials showed the potential applications of\nthe developed prototype platform for efficient and on-site analytical\ndetermination.