Colorimetric and fluorescent dual-channel sensor array based on Eriochrome Black T/Eu3+ complex for sensing of multiple tetracyclines

In this work, a dual-channel probe based on a complex of Eriochrome Black T (EBT) and Eu3+ ions (denoted as EBT/Eu3+) was used to sense four kinds of tetracyclines (TCs). UV–Vis and fluorescence spectra indicated that EBT/Eu3+ molecule has the ability to emit dual channel signals of color and fluorescence. When TCs with different structures were added to the EBT/Eu3+ solution, the color and the fluorescence intensities of EBT/Eu3+ solution varied with TCs structure. FT-IR spectra revealed that a coordinating reaction occurred between acylamino groups, hydroxyl groups of A-ring in TCs and Eu3+ ions. The coordinating ratio was 1: 2. Utilizing dual channel signals as well as the aid of principal component analysis (PCA), EBT/Eu3+ was capable of discriminating not only single TCs with concentrations in nano-molar level, but also binary mixtures of TCs. The results of controlled experiments on various interfering substances and other antibiotics proved that this method has high selectivity for TCs detection. Furthermore, this two-channel sensor array based on EBT/Eu3+ can also be used for the discrimination of unknown TCs in commercially available pork and honey with the 100% recognition accuracy. These results indicated that TCs with different structures can be rapidly discriminated by using a single and easily prepared sensor array.