The current strategy reports a highly sensitive and selective square wave-cathodic stripping voltammetric protocol for malathion determination. The established method was based on the controlled adsorptive accumulation of malathion in the presence of Cu²⁺ ions in an aqueous solution of pH 2 onto the hanging mercury dropping electrode (HMDE) and measuring the resulting cathodic peak current of the adsorbed species at 0.42V versus Ag/AgCl electrode. The low limits of detection (LOD) and quantification (LOQ) of malathion of the assay were estimated to be 3.1×10⁻¹⁰ and 1.03×10⁻⁹M with a linear dynamic range of 1.03×10⁻⁹ 2.0×10⁻⁷M, respectively. The method was satisfactorily applied and validated for malathion determination in environmental samples. The experimental Student t_exp and F_exp values did not exceed the tabulated t_tab (2.78) and F_tab (6.39) at 95 (P=0.05) confidence (n=5), confirming the precision and independence on the matrix. The developed sensing platform for the detection of malathion shows superior performance to conventional electrochemical methods. The proposed sensor offered simple, economical, reproducible, and applicable approach for the determination of malathion in environmental samples.

Nitrogen-Containing heterocyclic compounds are the most abundant and integral scaffolds that occur in a variety of synthetic drugs, bioactive natural products, pharmaceuticals and agrochemicals.

Several emerging nano scale forms of carbon are showing great promise in electrochemical sensing such as graphene and multi-walled carbon nanotubes (MWCNTs). Herein we present an ecofriendly method to fabricate long life and sensitive ion selective sensors based on graphene and MWCNTs nanocomposites with no need for volatile organic solvents. Both sensors were fabricated, for the analysis of carbachol in ophthalmic solutions, plasma and urine where ion- association complex was formed between cationic carbachol and anionic Sodium tetra phenyl borate (NaTBP) in a ratio 1:1. Both sensors were evaluated according to the IUPAC recommendation data, revealing linear response in the concentration range 10⁻⁷ M to 10⁻² M with near Nernstian slopes 50.80 ± 5 and 58.14 ± 3 mV/decade and correlation coefficients 0.9992 and 0.9998 for graphene and MWCNTs based sensors, respectively. Both sensors were successfully applied as stability indicating method for the analysis of carbachol in presence of its metabolite choline, in ophthalmic preparations, in plasma and urine showing good recovery percentage values. MWCNTs based sensor showed some advantages over graphene sensor regarding lower limit of detection (LOD), longer life time and higher selectivity towards carbachol. Statistical comparison of the proposed sensors with the official method showed no significant difference for accuracy and precision.

The detection of precious metal ion moieties is of utmost significance for environmental control. Thus, the current study provides a low cost and highly-accurate square wave adsorptive anodic stripping voltammetric procedure (SW-AdASV) at a Bi film (BiF/GCE) for the analysis of the lower levels of palladium (II) ions. The proposed SW-AdASV methodology was based on the selective accumulation of the palladium (II) chelat of the newly Schiff base reagent of 1,2 dihydroxy-cyclobut-1,2-ene-3,4-dione (DCED) in a universal buffer of pH=2-3. Under the optimized analytical parameters, the plot of the palladium (II) concentration versus the corresponding anodic peak current was linear over a wide range of [5×10-9 – 2.5×10-6 molL-1 Pd] with a correlation coefficient of R2=0.9995 and excellent repeatability with RSDs of (3.3-3.8%) (n=5). In the SW-AdASV approach, the lower limits of detection (LOD) and quantitation (LOQ) as calculated were discovered to be 1.07×10-9 and 3.57×10-9 molL-1, respectively. The current sensor offered interference from several active metal ions, such as Hg2+ and Cd2+. Lastly, the developed SW-AdASV method with (BiF/GCE) was successfully applied for the detection of lower levels of Pd2+ in water. Furthermore, this procedure presents a sensitive, accurate process with short analytical time, ruggedness, robustness, and reproducibility.

A bioanalytically validated potentiometric method was proposed for the assay of bisphenol A (BPA) using a MWCNT-modified graphite ion selective electrode. The sensitivity of measurements was significantly enhanced by using MWCNTs as an ion-to-electron transducer layer. A precise linear analytical curve was developed to determine BPA in a specified linear range of 10,000–0.01 μmol·L ⁻¹ , with a detection limit of 0.000104 μmol·L ⁻¹ . After confirming that the results obtained with the proposed potentiometric sensor are not affected by the presence of possible interferents, the method was successfully applied to determine BPA concentration in different saliva samples, giving good accuracy and precision.