A spectrophotometric method for the determination of glyphosate based on the monitoring of a complex formation between bis 5-phenyldipyrrinate of nickel (II) and the herbicide was developed. The method showed a short response time (10 s), high selectivity (very low interference from other pesticides and salts), and high sensitivity (LOD 2.07 × 10⁻⁷ mol/L, LOQ 9.87 × 10⁻⁷ mol/L, and a K_d from 1.75 × 10⁻⁶ to 6.95 × 10⁻⁶ mol/L). The Job plot showed that complex formation occurs with a 1:1 stoichiometry. The method was successfully applied in potable, urban, groundwater, and residual-treated water samples, showing high precision (0.34–2.9%) and accuracy (87.20–119.04%). The structure of the complex was elucidated through theoretical studies demonstrating that the nickel in the bis 5-phenyldipyrrinate forms a distorted octahedral molecular geometry by expanding its coordination number through one bond with the nitrogen and another with the oxygen of the glyphosate’ carboxyl group, at distances between 1.89–2.08 Å.

The preparation and properties of Nafion–TMS (Nafion–trimethylsilyl) and Nafion–TMS–Ru²⁺-complex modified GC electrodes are reported for the electrochemical oxidation reaction of adrenaline (AD). The structure of Nafion–TMS was studied by atomic force microscopy. The incorporation of [Ru(bpy)₃]²⁺ and [Ru(phen)₃]²⁺ complexes into Nafion–TMS was investigated by UV-vis spectroscopy, providing information about the interaction of the modified Nafion–TMS–Ru²⁺-complex composite. According to electrochemical studies, the electrodes modified with this composite polymer showed a faster electron transfer and greatly improved kinetics for the redox reaction of AD in standard solutions when compared to bare and Nafion–TMS modified electrodes. The oxidation current increased linearly with adrenaline concentration in the range from 1 to 20 mM and 1 to 100 mM for Nafion–TMS and the modified Nafion–TMS–Ru²⁺ complex, respectively. A strong pH dependence on the electroanalytical parameters was found for adrenaline detection, indicating that electron transfer reaction occurs in tandem with proton transfer.

The properties of Naf-TMS (Nafion-trimethylsilyl) and Naf-TMS/Ru-complex modified electrodes are reported for the electrochemical oxidation reaction of adrenaline (AD). The structure of Naf-TMS allows for hydrophobic and hydrophilic interactions with [Ru(bpy)3]2+ and [Ru(phen)3]2+ complexes in order to form stable Naf-TMS/Ru-complex polymer composites. Electrodes modified with this composite polymer, showed a faster electron transfer and greatly improved kinetic values for the redox reaction of AD in standard solutions, when compared to bare and Naf-TMS modified electrodes. A pH dependence of the electroanalytical parameters indicates that electron transfer reaction occurs in tandem with proton transfer, this allows to find the best analytical conditions for the detection of AD with Naf-TMS/Ru-complex modified electrodes.