Excessive addition of ethyl maltol (EMA) to foods poses potential health risks, highlighting the need for reliable monitoring. Herein, an integrated Fe(III)-driven liquid-phase microextraction (LPME)–spectrophotometry system was developed for selective and high-throughput EMA determination. Fe(III) in the acceptor phase served dual roles: as a chemical trap achieving >90% extraction efficiency and as an in situ chromogenic probe enabling direct detection. This unique design combines membrane-mediated matrix exclusion with coordination-assisted extraction, resulting in enhanced sensitivity and improved resistance to matrix interference. Density functional theory calculations revealed that Fe(III) facilitated the forward extraction by reducing the transmembrane transfer free energy barrier while suppressing back-extraction via weakening EMA–membrane solvent interactions. Under the evaluated conditions, the system offered a broad linear range (7.8–1500 μM, R 2 > 0.999), low detection limit (0.67 μM), and satisfactory selectivity toward structural analogues. Validation in diverse food matrices yielded recoveries of 88–107% with good agreement with HPLC–UV ( R 2 > 0.99). The minimal solvent consumption, high throughput, and favorable greenness further highlight its practical utility. More than an EMA detection method, this work provides a proof-of-concept for the coordination-driven LPME strategy that intrinsically integrates sample preparation with in situ signal generation, offering new insights into the design of a mechanism-driven microextraction system. Graphical abstract
Zhen-Wen Zhang,Ao-Jun Qiu,Geng-Jin-Sheng Cheng,Yu Fan,Yu Xiao,Yan-Zhu Liu,Qian-Yong Cao
Tetracycline detection remains an important research topic in the bioenvironmental field today. This paper reports a novel amphiphilic Eu(III) complex DO 3 AC 12 -Eu for single signal and ratiometric fluorescence detection of tetracycline (TC) in aqueous solution. DO 3 AC 12 -Eu can self-assemble micelle-like nano-aggregation in aqueous solution with no fluorescence. After addition of TC, the Eu(III)-based emission was observed for the effective antenna effect from TC to Eu(III) center. In addition, DO 3 AC 12 -Eu can load 4-methylumbelliferone sodium (MU) as a fluorescence reference to form DO 3 AC 12 -Eu/MU co-assembly nano-aggregation with a blue emission at 450 nm. Based on the TC-induced antenna effect and inner filter effect mechanism between TC and MU, DO 3 AC 12 -Eu/MU exhibits a ratiometrically fluorescent response toward TC, with increasing Eu(III)-based emission at 615 nm, and decreasing MU-based emission at 450 nm. Importantly, DO 3 AC 12 -Eu/MU exhibits superior sensitivity and selectivity over DO 3 AC 12 -Eu . The detection limit of DO 3 AC 12 -Eu/MU toward TC is 0.82 nM, far lower than that of DO 3 AC 12 -Eu (9.5 nM). Furthermore, DO 3 AC 12 -Eu/MU assembly has been successfully used for on-site and real-time detection of TC in food samples by using the smartphone-based visualization method and test gel.
Yanjia Guo,Juan Lu,Wenzhuo Wang,Hanyue Jiang,Guangping Ma,Pengfei Han,Li Tian,Tengying Ma
In this study, we developed novel copper-doped biomass carbon quantum dots (Cu-CQDs) utilizing cantaloupe peel and copper nitrate as precursors. Compared to undoped biomass carbon quantum dots (CQDs), the Cu-CQDs demonstrated a stronger electrochemiluminescent (ECL) signal when reacting with K 2 S 2 O 8 . By employing the synthesized Cu-CQDs as a luminescent reagent, we collaborated with the polymer donor PM6 to construct an innovative solid-state ECL sensor for the trace detection of Rhodamine B (RhB). The solid-state ECL sensor was developed using a layer-by-layer modification approach, sequentially modifying the electrode surface with the polymer donor PM6, Cu-CQDs, and chitosan (CS). The layered structure of the polymer donor PM6 serves as a carrier for Cu-CQDs, enhancing their effective concentration on the electrode surface. Additionally, its electron-donating properties facilitate electron transfer within the sensor system. Chitosan (CS), characterized by its viscosity, was modified as the outermost layer, further enhancing the stability and ECL intensity of the sensor. RhB exhibited a significant quenching effect on the ECL signal of the constructed sensor, with the quenching value being proportional to the logarithm of RhB concentration in the range of 5.0 × 10 −8 to 5.0 × 10 −13 M. This sensor was successfully applied to the detection of RhB in chili samples, providing an effective platform for food safety monitoring.
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