In this project, a prompt, efficient, and effective method for Cd²⁺ ions extraction from different food and water samples using magnetic dispersion-based solid phase extraction by functionalized iron oxide nanoparticles was proposed. Iron oxide nanoparticles were synthesized through the co-precipitation method followed by functionalization with tetraethyl orthosilicate (TEOS) and 3-aminopropyl silane (APTES) to obtain Fe₃O₄@SiO₂@APTES. This composite was characterized through different techniques, including vibrating sample magnetometer, dynamic light scattering, zeta potential, FTIR, SEM, XRD, and BET. Variables studied were pH, temperature, sorbent amount, sonication time, and sample and eluent volume affecting the sorption efficacy of freshly synthesized sorbent. Plackett–Burman design was utilized for the identification of significant factors for microextraction of target analyte, while the central composite design was utilized for the optimization of significant factors. Detection and quantification limits obtained were 0.17 and 0.58 μgL⁻¹, respectively, with an enhancement factor of 83.5. Under optimum conditions, Fe₃O₄@SiO₂@APTES showed good stability even after >80 adsorption/desorption cycles run while maintaining over 96% analyte recoveries. The developed method was validated by assessing certified reference materials and standard addition methodology for Cd²⁺ detection in real samples. To confirm the precision, repeatability (RSD_r) and reproducibility (RSD_R) were calculated and found as <3.0 (n = 7) and <7.5 (n = 15), respectively. Furthermore, in accordance with the ISO/IEC 17025 recommendations, the validation was also confirmed through a “bottom-up” approach while considering all possible uncertainties in data.

The catalytic conversion of aniline into azo compounds represents a significant and versatile route in synthetic organic chemistry, with applications spanning dyes, pharmaceuticals, and functional materials. This comprehensive review systematically examines recent advances in catalytic strategies for azo bond formation from aniline derivatives, encompassing homogeneous, heterogeneous, enzymatic, and photo-redox catalysis. Key mechanistic pathways, including oxidative coupling, dehydrogenative aromatization, and redox processes, are critically analyzed. The influence of catalyst design (e.g., transition metals, organo-catalysts, nanomaterials) and reaction conditions (solvent, oxidants, temperature) on selectivity and efficiency is discussed. Additionally, the review highlights sustainable approaches, such as aerobic oxidation and visible-light-driven catalysis, aligning with green chemistry principles. Challenges, including substrate scope limitations and scalability, are addressed, along with emerging trends and future prospects for industrial and academic applications. This work aims to serve as a foundational resource for researchers exploring catalytic azo compound synthesis.

In this study, apricot-pit-based activated carbon was functionalized and used as a sorbent for the preconcentration of lead (Pb²⁺) in different water and food samples. The activated sorbent was modified with ethylenediaminetetraacetic acid (EDTA) to enhance its selectivity for the efficient removal of Pb²⁺ ions. The modified activated sorbent was characterized using FTIR, an SEM, BET, and TGA. The column adsorption method was used to study the adsorption capacity of synthesized and modified activated carbon and analyzed using atomic absorption spectrophotometry. A multivariate procedure, i.e., Plackett–Burman design (PBD) and central composite design (CCD), was studied for optimizing the adsorption process, which allows the optimization of multiple variables at the same time. An interference study was conducted to ascertain the selectivity of the developed method. The developed method was validated by assessing certified reference materials and additional standards for Pb²⁺ detection in real samples. To assess the precision of the proposed procedure, repeatability (RSD_r) and reproducibility (RSD_R) were calculated, which were determined to be <3.0 (n = 7) and <7.5 (n = 15), respectively. The obtained results revealed that the modified AC is a suitable and efficient sorbent for the preconcentration of Pb²⁺ in real water and food samples.