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Exposure to lead (Pb) through drinking water has been linked to adverse health outcomes. Children are particularly susceptible. This study was designed to measure Pb contamination level in drinking water of the Ethiopian city Addis Ababa and assess the associated health risks. Eighty-eight fully-flushed drinking water samples were collected from all ten sub-cities of Addis Ababa. Pb concentration was measured using an Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The chronic daily intake (CDI), the hazard quotient (HQ), and the cancer risk (CR) of Pb were determined to assess exposure levels and health effects. Blood lead level (B–Pb) for children was modelled using the integrated exposure uptake biokinetic model (IEUBK). The mean concentration of Pb in the drinking water was 17.8 μg/l, where >50% of the samples exceeded WHO's 10 μg/l guideline. Significant spatial variation of Pb was noticed among sub-cities. The mean CDI was 1.43 and 0.59 μg/kg/day for children and adults, respectively. The HQ showed that 8% of children and 2.3% of adults exceeded the safe limit. The predicted geometric mean of B–Pb ranged from 3.23 to 14.65 μg/dl. The risk of a child having a B–Pb level >5 μg/dl at the median water Pb concentration (10.5 μg/l) was estimated at 13.4%. Based on the 95th percentile Pb concentration (75.1 μg/l), 89.6% of children would have B–Pb levels above the 5 μg/dl threshold. The estimated CR was found in the range of 1 × 10−7 to 9.9 × 10−5; hence cancer risks are not a concern. The study concluded that Addis Ababa's drinking water is likely to be a source of lead exposure where consumers at specific city locations are at risk of numerous non-cancer health effects. The impacts are expected to be severe in the Ethiopian context; hence further investigations and coordinated interventions are required.

A novel modified carbon paste electrode has been developed using a laboratory synthesized metal chelating ligand (L), N1‐hydroxy‐N1,N2‐diphenylbenzamidine (HDPBA) and multi‐walled carbon nanotubes (MWCNTs) composite (L‐MWCNTs/CPE). The developed modified electrode was applied for selective and sensitive simultaneous electrochemical determination of cadmium(II), lead(II), and mercury(II) using square wave anodic stripping voltammetry (SWASV). The accumulation of metal ions on the electrode surface was performed in 0.1 M acetate buffer solution (ABS, pH 5.0) by applying a potential of–1.10 V versus Ag/AgCl for 210 s, followed by stripping in the positive potential scan of the SWASV after a rest time of 10 s. Under the optimum experimental conditions, the linear dynamic ranges were found to be 2×10−4–2, 1×10−4–2 and 2×10−3–2 μM of cadmium(II), lead(II), and mercury(II), respectively, with the detection limits (LODs) of 2.5×10−2, 7.8×10−3 and 4.6×10−1 nM for cadmium(II), lead(II), and mercury(II), respectively. The proposed electrode exhibited high sensitivity for the determination of these metal ions with excellent reproducibility and stability. The influence of several ions on the simultaneous determination of Cd(II), Pb(II), and Hg(II) was studied, and the prepared electrode was found to be highly selective for the detection of the three metal ions. The developed electrode was effectively applied to the determination of the three metal ions in water, vegetable and tobacco samples, and the obtained results were similar to those measured with graphite furnace atomic absorption spectrometry (GFAAS). [ABSTRACT FROM AUTHOR]

The present study introduces a novel electrode for rapid, highly sensitive, and selective electrochemical sensor for cadmium(II) using 5% N1-hydroxy-N1,N2-diphenylbenzamidine (HDPBA) modified carbon paste electrode (CPE) (HDPBA‒CPE). Surface characterizations and structural analysis of the proposed HDPBA‒CPE were performed using several analytical techniques. The voltammetric measurements of Cd(II) were conducted by cyclic voltammetry (CV) and square wave anodic stripping voltammetry (SWASV). Several experimental conditions such as composition and pH of buffer solutions, HDPBA composition, accumulation potential and time, and other voltammetric conditions were optimized. Cd(II) was preconcentrated on the modified electrode surface for 270 s using Britton Robinson (B-R) buffer (0.1 M, pH 4) at −1.0 V versus Ag/AgCl, followed by electrochemical oxidation of the accumulated Cd(II) in the positive scan of SWASV after a quiet time of 10 s. Under optimized parameters, the proposed method showed a linear range of 0.3–100 nM Cd(II) with a detection limit of 0.032 nM. The fabricated HDPBA-modified carbon paste electrode exhibited excellent sensitivity, selectivity, stability, and reproducibility (with RSD of 3.8%). The developed HDPBA‒CPE was used for the quantification of Cd(II) in tobacco and environmental water samples, and it was found to be applicable for the determination of different types of real samples. [ABSTRACT FROM AUTHOR]

Mercury is a highly toxic metal, of which even small doses (<200 ng mL−1) can cause serious problems for humans, plants, animals and microorganisms, including marine species and freshwater organisms. Hence, a simple, fast, highly selective and sensitive and accurate method for the detection of mercury in the environmental, clinical or biological samples is necessary. A new, sensitive and selective method for the determination of Hg(II) with 5 % N1‐hydroxy‐N1,N2‐diphenylbenzamidine modified carbon paste electrode has been developed. Hg(II) was accumulated for 210 s on the surface of the modified electrode using 0.1 M CH3COONa of pH 7 at −0.8 V vs Ag/AgCl, followed by electrochemical stripping with SWASV in 0.1 M NH4Cl at pH 4. The linear range is 0.02–10 μM Hg(II) with limit of detection of 1.28 nM. The method has RSDs of 3.7 %. The method was applied for the determination Hg(II) in five types of water samples. The recoveries were in the range 97.8–103 %. The proposed method was found to be highly selective and sensitive and has many attractive features compared to previous reports such as low cost, simplicity of electrode preparation, long term stability, fast response, easy renewable ability, and reasonable short accumulation time. [ABSTRACT FROM AUTHOR]

The present study introduces a novel electrode for rapid, highly sensitive, and selective electrochemical sensor for cadmium(II) using 5% N 1 -hydroxy-N 1 ,N 2 -diphenylbenzamidine (HDPBA) modified carbon paste electrode (CPE) (HDPBA‒CPE). Surface characterizations and structural analysis of the proposed HDPBA‒CPE were performed using several analytical techniques. The voltammetric measurements of Cd(II) were conducted by cyclic voltammetry (CV) and square wave anodic stripping voltammetry (SWASV). Several experimental conditions such as composition and pH of buffer solutions, HDPBA composition, accumulation potential and time, and other voltammetric conditions were optimized. Cd(II) was preconcentrated on the modified electrode surface for 270 s using Britton Robinson (B-R) buffer (0.1 M, pH 4) at -1.0 V versus Ag/AgCl, followed by electrochemical oxidation of the accumulated Cd(II) in the positive scan of SWASV after a quiet time of 10 s. Under optimized parameters, the proposed method showed a linear range of 0.3-100 nM Cd(II) with a detection limit of 0.032 nM. The fabricated HDPBA-modified carbon paste electrode exhibited excellent sensitivity, selectivity, stability, and reproducibility (with RSD of 3.8%). The developed HDPBA‒CPE was used for the quantification of Cd(II) in tobacco and environmental water samples, and it was found to be applicable for the determination of different types of real samples., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2022 Endale Tesfaye et al.)