Studies of simultaneous electrochemical sensing of hydroquinone and catechol, and fluorescence sensing of resorcinol by katiragum dialdehyde-histidine Schiff base†

Abstract

A novel katiragum dialdehyde-histidine Schiff base (KGDHSB) is synthesized and characterized for the selective and efficient detection of hydroquinone (HQ), catechol (CL), and resorcinol (RL) in aqueous media. The synthesis involves the selective oxidation of katiragum's C₂–C₃ bond with sodium meta periodate (NaIO₄) to yield katiragum dialdehyde (KGD), followed by condensation with L-histidine. The structure of KGDHSB is confirmed using various analytical techniques, including ¹H NMR, ¹³C NMR, FTIR, HRMS, TGA, and FESEM with EDAX analysis. KGDHSB-modified glassy carbon electrode (KGDHSB/GCE) is used in electrochemical sensing experiments. Differential pulse voltammetry (DPV) experiments revealed that KGDHSB can simultaneously detect HQ and CL with limits of detection (LOD) of 0.809 nM and 1.03 nM, and limits of quantification (LOQ) of 2.69 nM and 3.45 nM, respectively. The sensitivity values are calculated to be 5.558 × 10⁻⁵ A nM⁻¹ cm⁻² and 4.347 × 10⁻⁵ A nM⁻¹ cm⁻² for HQ and CL, respectively. Furthermore, KGDHSB is also used as a fluorescent probe for the sensing of RL in fluorometric methods which demonstrates that KGDHSB can detect RL with a LOD value of 0.43 nM, LOQ value of 1.43 nM, and it binds with RL in a 1 : 1 ratio with a binding constant of 0.00982 nM⁻¹. Notably, KGDHSB exhibits a significant quantum yield of 0.448% in comparison to fluorescein (0.97%). Both experiments demonstrate excellent selectivity, sensitivity, stability, and reproducibility, showcasing KGDHSB's potential as a reliable sensor for environmental monitoring of HQ, CL, and RL. Notably, the sensor achieves impressive recovery percentages of 97.4–100.2% for HQ and 98.2–99.93% for CL, with low relative standard deviation (RSD) values ranging from 1.98–4.17% for HQ and 1.31–4.11% for CL, confirming its viability for practical applications.