Novel analytical sensing strategy using a palladium nanomaterial-based electrode for nimesulide electrochemical reduction

Abstract

• A novel nanopalladium–silsesquioxane composite was designed. • Modifier material was characterized and applied for NIM sensing through reduction. • Long-term stability for the nanomaterial with the guarantee of reproducibility. • NIM voltammetric detection with low LOD and widest linear response range. • Accuracy and selectivity in the electroanalysis of environmental and clinical samples. Nimesulide (NIM) is a non-steroidal anti-inflammatory drug considered an emerging contaminant. Thus, a novel sensing platform composed of an ionic silsesquioxane material and palladium nanoparticles (PdNPs) was designed for NIM sensing. First, PdNPs were synthesized with a mean size of 1.3 nm according to transmission electron microscopy and small-angle X-ray scattering analyses. Then, the bare glassy carbon electrode (GCE) was modified by drop-coating with PdNPs stabilized in a silsesquioxane hybrid material (Si4Pic + NO 3 – ). Electrochemical impedance spectroscopy and cyclic voltammetry performed the electrochemical characterization. Using the electrochemical sensor GCE/Pd-Si4Pic + NO 3 – and optimized conditions of differential pulse voltammetry, in PBS 0.4 mol L –1 , pH 6.5, the peak current intensity varied linearly in the range of 0.13 – 60 μmol L –1 . The limits of detection (LOD) and quantification (LOQ) were estimated as 39 nmol L –1 and 0.132 µmol L –1 respectively (E d = −0.4 V; t d = 80 s). Indeed, the proposed sensor showed an anti-interference response for some metallic cations and inorganic anions as well as humic acid. The proposed analytical method was employed for NIM determination in simulated spiked serum, synthetic urine, and river water samples focusing on the reduction process. Selectivity was investigated; at a significance level of 99 %, the matrix did not interfere with the analysis. Molecular absorption spectrometry evaluated the accuracy; good correspondence was obtained for both methods. The novel method based on a simple and attractive one-step electrode modification is a promising environmental and clinical analysis tool.