Exploring the potential of Triton X-100–assisted thioridazine–rose Bengal adduct as an optical chemosensing probe for detection of thioridazine drug residues in water

Abstract

Precise quantification of thioridazine (TDZ) drug residues in water samples is essential due to its widespread use. Thus, this study reports low-cost optical chemosensing probe based on Triton X-100 assisted thioridazine (TDZ) -rose Bengal (RB) associate for TDZ detection in water. The planned probe was based upon liquid–liquid extraction (LLE) of the formed adduct between the ion associate [TDZ⁺·RB⁻] of the protonated TDZH⁺ and RB and Triton X-100 at pH 5 followed by extraction into dichloromethane and spectrophotometric measurement at 580 nm. Under optimized conditions, the developed probe displayed good linear range (LR) of 0.05–4.0 μg mL⁻¹ (1.34 × 10⁻¹–1.07 × 10¹ μ mol L⁻¹), with limits of detection (LOD) and quantification (LOQ) of 1.0 × 10⁻² and 3.33 × 10⁻² μg mL⁻¹, respectively. Notably, the incorporation of TX-100 significantly enhanced the sensitivity of [TDZ⁺·RB⁻] associate through formation of a surfactant-assisted adduct, [(TDZ⁺·RB⁻)·(Triton X-100)ₙ]_org, reducing the LOD and LOQ to 2.0 × 10⁻³ and 6.66 × 10⁻³ μg mL⁻¹, respectively. The extraction constants (D, K_ex, and β), along the stoichiometric, stability, and thermodynamic parameters of the developed associate were systematically evaluated. The low value of ΔH (46.03 J mol⁻¹) revealed the endothermic nature of the ion association reaction and the driving force is not electrostatic interactions but it includes an entropic component and an enthalpic component, stemming from Columbic attraction between opposite charges. The probe displayed good sensitivity and selectivity towards TDZ detection in water. Student's t-test and intra−/inter-day analyses confirmed precision, accuracy, and long-term stability.