Nanoscale Zr(IV)\nMOF-Embedded Chitosan on Paper Composite\nfor Aqueous Phase Detection of the Herbicide Metamitron and the Food\nColorant Tartrazine

With the accelerated progression of modern society, artificial\ncolorants are utilized extensively for their attractive coloration.\nHerbicides are applied widely to control unwanted plants in agricultural\nfields which cause toxic effects on human health and the environment.\nThe increased utilization of these toxic chemicals has necessitated\nthe development of a highly sensitive sensor that can selectively\nidentify these toxic chemicals. In this study, we explored a nanoscale\nZr­(IV)-based metal–organic framework (MOF) (<b>1′</b>) as a fluorescence sensor toward precise recognition of food colorant\ntartrazine and herbicide metamitron. The quenching efficiency of <b>1′</b> toward tartrazine and metamitron was 93 and 88%,\nrespectively. The limit of detection was found to be 5.7 nM for tartrazine\nand 13.7 nM for metamitron, which are remarkably lower than the other\nreported sensors. Moreover, the quick response time (<10 s for\ntartrazine and <20 s for metamitron) and recyclable property of <b>1′</b> made it a promising candidate for real-world application.\nFurthermore, <b>1′</b> was utilized for the detection\nof tartrazine in various food matrices, which displayed a very good\nrecovery percentage. This study also highlights the potential of <b>1′</b> toward real-time detection of metamitron in different\nenvironmental water systems and a variety of pH media. Additionally,\nwe have prepared cost-effective, user-friendly Zr­(IV) MOF-embedded\nchitosan on paper composite for the hands-on detection of tartrazine.\nWe have elaborately investigated the mechanisms of fluorometric sensing\nwith several instrumental techniques. Adsorption capacity of <b>1′</b> toward tartrazine was also measured and it showed\nfast adsorption (<1 min). It also displayed over 90% selectivity\nfor adsorption of tartrazine in the presence of commonly occurring\ncations and anions.