Facile utility of felumin, a biological dye for the first fluorimetric determination of l-tetramisole drug through an “on–off fluorescence” strategy

l-Tetramisole is an anti-nematode and immunomodulating agent employed medically to treat diseases caused by worms. It is also used as an immune system-modifying agent in rheumatoid arthritis and as assistant therapy in treating cancers in the colorectal, head, and neck regions. Felumin is a safe food dye used in feed additives, flavors, biostaining, and recently, in analytical tracking. This is the first innovative spectrofluorimetric approach to l-Tetramisole drug analysis. It is both efficient and environmentally benign and was evaluated and validated in this investigation using a green, one-pot, and direct spectrofluorimetric technique. Instant complexes were created by combining l-Tetramisole and Felumin in an acidic solution. The fluorometric investigation was performed based on the off-effect strategy of l-Tetramisole on the emission amplitude of a biological dye (Felumin) at 557.5 nm. The linear range was from 0.1 to 1.7 μg mL(−1), with sensitivity limits of 0.020 and 0.061 μg mL(−1), respectively. Analytical modulation of l-Tetramisole–Felumin complexes was done for all system parameters. The system was found to meet ICH criteria. Moreover, this technique successfully recovered the substance in the prescribed medicinal dosage forms. The created fluorimetric technique was also successfully employed to track the drug of interest in human biofluids, which was a major accomplishment. The kinetics of the reaction system was also studied further. Finally, the proposed method's environmental friendliness was evaluated on the eco-scale.