The widespread of plastic piping applications in water distribution systems and home plumbing network has brought many health concern dues to the water quality deterioration from the occurrence of leachable organic pollutants into tape water. Among these pollutants, volatile organic molecules are believed to migrate easily from the popular polyethylene piping. This study aimed to screen the occurrence of volatile organic compounds leachable from plastic pipes comprising home water network system in residential homes located in Medina Al-Munawarah city. For this purpose, a total of 28 water samples were collected from different houses of various ages. The presence of Ethyl methacrylate, 1,2Dichloroethane, Dibromochloromethane, 1,2,3Trichloroethene, Xylene, pyridine ,1,1,2,2Tetrachloroethane, Benzyl chloride, 1,2Dichlorobenzene and 2Picoline were analysed. Although some of the levels of the pollutants studied were within the allowed limit, however, the level of 1,2Dichloroethane, 1,2,3Trichloroethane and 1,2Dichlorobenzene exceeded the pe rmissible levels in 62.07%, 10.34% and 13.79% of homes, respectively. The leachability study that was conducted to correlate volatile organic contaminants to plastic pipes, indicated that all the volatile compounds were migrated from the widely used polyethylene pipes. However, apart from benzyl chloride and 1, 2 dichloroethane which were detected in low levels, the other compounds not being found in source water. This initial screening confirmed that the plastic piping could be considerable source for the contamination of tape water with volatile organic compounds.

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.

This study reports a highly sensitive electrochemical sensor based on Bi film modified glassy carbon electrode (BiF/GCE) for total determination and speciation trace concentrations of copper(II) ions in environmental water samples. Square wave‐adsorptive anodic stripping voltammetric (SW‐ASV) experiment was performed for monitoring selective accumulation of copper(II) with reagent 3‐[(2‐mercapto‐vinyl)‐hydrazono]‐1,3‐dihydro‐indol‐2‐one (MHDI) at pH 9–10. The mechanism of the electrode reaction of Cu2+‐MHDI complex was safely assigned. The sensor exhibited a wide linear range (3.22×10−9–2.0×10−7 mol L−1) with lower limits of detection (LOD) and quantitation (LOQ) of 9.6×1−10 and 3.22×10−9 mol L−1, respectively (R2=0.9993). The proposed sensor exhibited interference from active metal ions e. g. Cd, Hg. The performance of the proposed method was compared successfully with most of the reported methods and comparable efficiencies were obtained. The analytical utility of the proposed SW‐ASV method has been successfully validated for trace analysis of copper(II) in environmental water samples. The method offers a precise, accurate approach with good reproducibility, robustness, ruggedness, and cost effectiveness.

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