Indirect fibre-optic colorimetric determination of ascorbic acid using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol and cloud point extraction

An On-off Supramolecular Fluorescence Switch for Detection of Pb2+ Ions and Vitamin C

β-cyclodextrin-hydroxyquinoline functionalized graphene oxide (GO-CD-HQ) was facilely fabricated to monitor and quantitatively analyze cations in aqueous media. The optical probe was notably selective enhanced toward Pb²⁺ ions over the other tested ions like Cu²⁺, Hg²⁺, Ca²⁺, Na⁺, K⁺, Zn²⁺, Fe²⁺, Fe³⁺, Ag⁺, Mg²⁺, and Cd²⁺ at 468 nm as an emission wavelength. The probe was shown the best performance in pH value, 5, and optimum time 1 min. Absorption spectra have clearly confirmed the static type fluorescence enhancement mechanism of GO-CD-HQ. Under the optimal conditions, the detection limit of it and linear concentration range for Pb²⁺ ions were obtained as 3.72 × 10^-5 M and (5-60) × 10^-5 M, respectively. Additionally, the developed assay exhibited logic gate behavior with Pb²⁺ ions and vitamin C as a masking agent for cited ions.