Dualistic Fluorescence as Well as Portable Smartphone-Assisted RGB-Relied Sensing Assay for the Ultra-Sensitive Determination of Pendimethalin in Food and Water Samples by AIEE Active Organic Probes.

Abstract

Herein, a peculiar fluorometric as well as smartphone-assisted RGB-relied sensing assay is introduced for determining pendimethalin (PDM) herbicide contents (in parts per trillion level) based on the anthracene-incorporated pyrimidinone/thione probes (S1 to S4). These compounds offered a unique and impressive aggregation-induced emission enhancement (AIEE) behavior by aggregation in H2O-dimethylformamide medium. Furthermore, these AIEE active compounds were found to display superior selectivity and extraordinary sensitivity for PDM detection via fluorescence quenching response. The extent of quenching degree was found to be linearly varied with the PDM concentration ranging from 0 to 20 nM, with a lower limit of detection of 367.8 pM (103.4 ppt) by S3 nanoaggregates. The detailed investigation revealed that such a high sensitivity of the designed sensor toward PDM is attributable to the existence of dual "photoinduced charge transfer and Förster resonance energy transfer process mechanisms". The Stern-Volmer plots, Job's plot, Benesi-Hildebrand plot, and 1H NMR titrations as well indicated the existence of substantial interactions between the sensor and PDM. The conducted selectivity tests provided distinguishable selectivity for PDM detection over various other insecticides/pesticides as well as other structural nitro analogues. Additionally, the presented sensing assay was also applied to quantify the PDM residues in spiked food (vegetables, fruits, and grains) and water samples. In addition, the sensor-coated fluorescent paper test strips were also fabricated for on-site detection of PDM. The applicability of smartphone-relied RGB analysis significantly streamlined the operation process, speeds up the detection procedure, and also offered a novel methodology for real-time analysis of PDM in real samples.