A fluorometric chemosensor for the sequential determination of Fe(iii) and cefotaxime sodium in water samples, serum and commercial formulations: a computational and an experimental approach

Abstract

An indole-based chemosensor (P1) was synthesized and characterized using FT-IR and ¹H NMR and was investigated fluorometrically for the determination of various metal ions. It was found that Fe(III) caused significant quenching compared to other metal ions, resulting in the formation of a non-fluorescent complex P1/Fe(III). Subsequently, the complex P1/Fe(III) represented as P2 was further utilized as a chemosensor for detecting cefotaxime sodium (CFT), an antibiotic. The fluorescence intensity of P2 was significantly decreased by the introduction of CFT into the complex mixture. Under optimum conditions, the linearity was found in the range of 0.3–3.0 µg mL⁻¹ for Fe(III) and 0.5–5 µg mL⁻¹ for CFT, and the LOD and LOQ were calculated to be 0.08 µg mL⁻¹ and 0.28 µg mL⁻¹ for Fe(III), and 0.12 µg mL⁻¹ and 0.4 µg mL⁻¹ for CFT, respectively. In addition, a theoretical study using DFT and QTAIM analyses predicted the formation of a thermodynamically feasible complex between the P1 and Fe(III) and CFT, stabilized by van der Waals forces and a dative-type of interaction. Furthermore, the probe P1 was applied for the determination of Fe(III) in water samples, and P2 was employed for the determination of CFT in serum samples and commercial formulations.