A chemosensing approach for the colorimetric and spectroscopic detection of Cr3+, Cu2+, Fe3+, and Gd3+ metal ions

Metal cations are present in domestic and industrial wastewater and have adverse effects on human and aqueous life. The present study describes the development of the molecular probe 9-anthracen-9-ylmethylene)hydrazineylidene) methyl)-2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolin-8-ol (AMHMPQ) to detect Cr3+, Cu2+, Fe3+, and Gd3+ ions by using UV-visible, fluorescence, colorimetric and excitation-emission matrix (EEM) spectroscopy techniques. The interaction of Cr3+, Cu2+, Fe3+, and Gd3+ can be observed by the absorption maxima shift, turn-off, colour changes, and EEM shifts. In addition, fluorescence limits of detection 17.66 x 10(-6) M, 6.44 x 10(-9 )M, 28.87 x 10(-8) M, and 12.49 x 10(-6) Min wide linear ranges, low limits of quantifications, high values of Stern-Volmer constant, Job's plot and Benesi-Hildebrand plot justify the 1:1 association affinity with association constants of 1.46 x 104 M-1, 1.86 x 107 M-1, 2.69 x 105 M-1, 2.13 x 104 M-1 for AMHMPQ-metal ions (Cr3+, Cu2+, Fe3+, and Gd3+ ions), respectively. Paper-and mask-based kits are developed to explore the utility of the designed chemosensor. Additionally, AMHMPQ acts as a reusable sensor for two, seven, two, and zero cycles for Cr3+, Cu2+, Fe3+, and Gd3+ ions, respectively, when checked with EDTA.

Automated summary

A molecular probe was developed in this study to detect metal cations in wastewater using various spectroscopy techniques. The probe showed high sensitivity and a wide linear range, making it a reusable sensor.