Nanoscale Zr(IV) MOF-Embedded Chitosan on Paper Composite for Aqueous Phase Detection of the Herbicide Metamitron and the Food Colorant Tartrazine

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