Lanthanide ions as sensor elements based sensor array for colorimetric identification of antioxidants

Abstract

A colorimetric sensor array consisting of three lanthanide ions (Eu3+, La3+, and Sm3+) as sensor elements and Eriochrome Black T (EBT) as signal readout was designed. In the presence of lanthanide ions, EBT and lanthanide ions form binary complexes, producing a color change from blue to pink. Upon the addition of antioxidants, the sensor array exhibits cross-reactive responses to antioxidants, the varying color and absorbance changes from the competitive binding from EBT and antioxidants to lanthanide ions were observed. Distinct colorimetric response variations as “fingerprints” were obtained on the sensor array, and then identified through linear discriminant analysis (LDA). LDA illustrates that the sensor array could differentiate five antioxidants (quinolinic acid (QA), 2,3-Pyridinedicarboxylic acid (PA), tannic acid (TCA), tartaric acid (TA), and gallic acid (GA)) at seven concentrations (5, 10, 50, 100, 150, 200, and 250 nM). This demonstrates the potential utility of the sensor array for diagnostic and food monitoring applications.