Nanomolar detection of organic pollutant -tartrazine in food samples using zinc-metal organic framework/carbon nano fiber - composite modified screen-printed electrode

In this study, we achieved a significant breakthrough by applying a binder -free Zn-MOF@CNF composite as a modifier on a screen-printed electrode (SPE) to achieve highly sensitive and selective detection of tartrazine (TRZ). This composite, with its unique rod -like structure for Zn-MOF and a curl thread-like morphology for carbon nanofibers (CNF), demonstrated a remarkable threefold increase in the sensing current of TRZ at a lower anodic oxidation potential (0.92 V) compared to the bare SPE. The Zn-MOF@CNF/SPE also exhibited a reduced charge transfer resistance of 61.9 ohm, elevated electrochemical active surface area of 0.416 cm 2 , and high heterogeneous electron transfer rate constant ( k 0 ) of 9.77x10 - 5 cm s - 1 . Furthermore, it displayed a broad linear range from 0.2 mu M to 1000 mu M with a remarkable sensitivity of 0.136 mu A mu M - 1 cm - 2 and an impressive detection limit of 54 nM. Ultimately, the developed Zn-MOF@CNF/SPE sensor demonstrated excellent selectivity amidst various structurally similar overlapping species, outstanding repeatability, reproducibility, and stability in TRZ detection. The practical applicability of Zn-MOF@CNF/SPE was validated through 97 - 100.9 % recovery results in food samples such as jelly, ice cream, soft drinks, and candies.