Metal distribution and human health risk assessment in legumes crops (chickpea, lentils and peas) from Belesa districts, Ethiopia.

Accumulation of heavy metals in food is a major concern for humans' health. This study was aimed at determining the levels of Cu, Fe, Mn, Ni and Zn in chickpea, lentil and pea samples and evaluating the health risk for consumers. The concentrations (in mg/kg) of Cu, Fe, Mn, Zn, and Ni were varied from 23.6-48, 67.7-132.3, 15-26.5, 37.6-68.2, and 25.5-33.3 in chickpea, 39.8-80.5, 116.1-180.5, 12.1-21.6, 36.4-57.2, and 25.4-34.1 for lentil and 32-64.2, 51.6-100.0, 6.3-15, 25.3-42.5, and 25.5-48.5 for peas, respectively. Pearson correlation verified that strong positive correlations were observed between Cu and Zn in lentils, Ni and Mn, Fe with Cu and Mn in peas. Target hazard quotients (THQ) except Ni in all samples, Cu in lentil and pea were < 1 and the hazard index (HI) values of all heavy metals were greater than 1, thus an appropriate strategy is required to reduce exposure to heavy metals.

Biosynthesis, characterization and study of the application of silver nanoparticle for 4-nitrophenol reduction, and antimicrobial activities.

Silver nanoparticles (AgNPs) were synthesized from Vigna unguiculata (L) Walp extracted leaves, and characterized. The UV-Visible spectrum showed a peak between 411 and 415 nm at the Plasmon absorbance of the AgNPs. TEM showed that the size of AgNPs ranged from 5 to 13 nm. It was spherical with an average size of 11.08 nm. The size of AgNPs was 7 ± 6 nm and disperse in water. The AgNPs effectively reduced 4-Nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of NaBH4. The AgNPs exhibited a strong antioxidant and antibacterial activity against Gram-negative bacteria: Escherichia coli (E. coli) and Klebsiella pneumonia and Gram-positive: Bacillus pumilus and Staphylococcus aureus. The average zones of inhibition of AgNPs were: 29 mm for Staphylococcus aureus, 23 mm for Bacillus pumilus, 17 mm for Klebsiella pneumonia and 15 mm for Escherichia coli (E. coli). Thus, AgNPs has exhibted good antibacterial activity compared to antibiotics drug and 4-NP reduction.

Analysis of nutrient loads, heavy metals and physicochemical properties of wastewater, wetland grass, and papaya samples: Gondar Malt factory, Ethiopia with global implication.

Robust attention was brought to researchers due to deterioration of wastewater quality of lakes and reservoirs as major global concerns by industrial release. The uncontrolled releases of effluents impose serious impacts for both aquatic and terrestrial environments. In the current study, many parameters like nutrient loads, heavy metals and physicochemical properties of wastewater, wetland grass, and papaya samples were analysed. The investigated nutrients, alkalinity, and total hardness in fresh water samples were within the allowable limits except for phosphate in fresh wastewater and alkalinity in wastewater. The detected levels of heavy metals (mg/L) in wastewater samples were:- Cd (0.386-0.905), Cr (ND-0.074), Cu (0.064-0.096), Mn (0.184-1.528), Fe (0.167-4.636), Zn (0.175-0.333), and Pb (0.044-0.892) (mg/L). The studied metals in the wastewater sample, except Cd, Fe, and Pb were lower than the allowable limit. The level of heavy metals in the grass and papaya samples ranged from Cd (37.14-147.62), Cr (ND-8.82), Cu (3.14-8.33), Mn (2.89-85.46), Fe(5.0-65.15), Zn (3.44-36.84), and Pb (ND-60.36) (mg/kg). The detected metals were below the permissible limits, except Cd, Cr, and Pb. The findings of the physicochemical characteristics in wastewater samples were computed: pH (6.61-8.54), temperatures (21.63-26.57 °C), TDS (205.9-1896 mg/L), EC (359.9-3226.67 µs/cm), BOD (12.0-732.67 mg/L), COD (3.67-1691.33 mg/L). Except for temperature and pH, all levels in the wastewater were above the recommended limit for wastewater discharge by USEPA.

Selective Determination of Norfloxacin in Pharmaceutical Formulations and Human Urine Samples Using Poly(8-aminonaphthaline-2-sulfonic Acid)-Modified Glassy Carbon Electrodes.

In this study, a glassy carbon electrode was modified potentiodynamically with poly(8-aminonaphthaline-2-sulfonic acid) [poly(ANSA)/GCE] for the detection of norfloxacin (NFN) in tablet formulations and human urine samples. Improvement of the effective surface area of the modified electrode and decreased charge-transfer resistance confirmed surface modification of the GCE by a conductive poly(ANSA) film. The appearance of an oxidative peak without a reductive peak in the reverse scan direction showed the irreversibility of the electrochemical oxidation of NFN in both the bare GCE and poly(ANSA)/GCE. A better coefficient of determination for the peak current on the square root of the scan rate (R2 = 0.99514) than the scan rate (R2 = 0.97109), indicating the oxidation of NFN at the poly(ANSA)/GCE, was predominantly diffusion mass transport-controlled. Under optimized pH and square wave parameters, the voltammetric current response of NFN at the poly(ANSA)/GCE showed linear dependence on the concentration, ranging from 1.0 × 10-8 to 4.0 × 10-4 M with a limit of detection of 4.1 × 10-10. The NFN level in the studied tablet brands was in the range of 90.30-103.3% of their labeled values. Recovery results in tablet and urine samples ranged from 98.35 to 101.20% and 97.75 to 99.60%, respectively, and interference recovery results were less than 2.13% error in the presence of ampicillin, chloroquine phosphate, and cloxacillin. The present method had a better performance for the determination of NFN in tablet formulations and urine samples as compared with recently reported voltammetric methods due to its requirement of a simple electrode modification step, which provides the least limit of detection and a reasonably wider linear dynamic range.

Analysis and health risk assessments of some trace metals in Ethiopian rice (white and red) and imported rice.

In this study, the levels of some trace metals (Cr, Cu, Mn, Pb, and Zn) in Ethiopian and imported rice samples were analysed. The rice samples were digested with a mixture of HNO3:HClO4:H2O2 (3:2:1 v/v) at a temperature of 200 °C for 2:30 h. The mean concentrations (mg/kg) of metals in Ethiopian and imported rice samples were found in the range of 4.82-17.04 for Cr, 11.30-18.30 for Cu, 6.04-9.22 for Mn; and 17.15-27.37 for Zn, within FAO/WHO limits. However, Pb was not detected in both rice samples. The Red rice contained higher levels of metals compared with the White rice. The Ethiopian rice recorded higher levels of metals than the imported ones. The estimated daily intake (mg/kg-day) was found to be at a safe level with reference to the maximum tolerable daily intake. Except for Cr, the values of the target hazard quotient (THQ) were also within the safe level in all the samples, posing no potential health risks on consuming rice. The hazard index values (HI) for the metals in Ethiopian rice except Jimma Red were slightly higher than unity, indicating the alert threshold level and potential health risks to rice consumers. Thus, the concentrations of these metals were less than the maximum limits set by FAO/WHO limits and most of THQ and HI values less than unity. Therefore, there was no serious noncarcinogenic risk to human health from exposure to metals through the consumption of these rice.

Determination of proximate composition, selected essential and heavy metals in sesame seeds (Sesamum indicum L.) from the Ethiopian markets and assessment of the associated health risks.

In this study, the proximate composition, levels of essential and heavy metals; and health risk assessment were evaluated in sesame seed (Sesamum indicum L.) samples purchased randomly from local markets of three study sites in Ethiopia. A 0.15 g of dried and homogenized samples were digested using 6 mL of HNO3 (69-72%) and 3 mL of HClO4 (70%) at 120 °C for 3 h. The levels of proximate composition and essential metals in the sesame samples were determined by the Association of Official Agricultural Chemists (AOAC) and Flame Atomic Absorption Spectrometer (FAAS), respectively. The moisture content, crude fiber, ash content, fat, crude proteins and carbohydrate of sesame samples ranged between 3.15% and 5.52%, 4.21-4.40%, 3.10-4.75%, 55.75-56.9%, 22.65-23.39% and 8.34-8.80%, respectively. The accuracy of the procedure was validated by percent recovery of samples for all metals varied from 85.60% to 102.00%. The mean levels of the metals (mg/kg) were found in the range of 37.20-70.10 (Na), 315.1-338.00 (K), 209.00-216.50 (Mg), 328.00-341.30 (Ca), 12.60-12.90 (Fe), 4.90-5.00 (Cu) and 8.30-8.70 (Zn) mg/kg. The THQ values of heavy metals were found < 1, indicating that the consumption of sesame may not cause health risks to local consumers. The values of HI ranged from 1.5 × 10-3 to 1.8 × 10-3 in the study areas and may not have a possible adverse health effect on the adult population from the consumption of sesame seeds.

Potentiodynamic Poly(resorcinol)-Modified Glassy Carbon Electrode as a Voltammetric Sensor for Determining Cephalexin and Cefadroxil Simultaneously in Pharmaceutical Formulation and Biological Fluid Samples.

This study covers the development of a fast, selective, sensitive, and stable method for the simultaneous determination of cephalosporins (cephalexin (CLN) and cefadroxil (CFL)) in biological fluids and tablet samples using potentiodynamic fabrication of a poly(resorcinol)-modified glassy carbon electrode (poly(reso)/GCE). The results of cyclic voltammetry and electrochemical impedance spectroscopy supported the modification of the GCE by a polymer layer that raised the electrode surface area and conductivity. At the poly(reso)/GCE, an irreversible oxidative peak with four- and fivefold current enhancement for CLN and CFL, respectively, at a substantially lower potential demonstrated the catalytic action of the modifier. Under optimized solution and parameters, the peak current response at the poly(reso)/GCE revealed a linear dependence on the concentration of CLN and CFL within the range 0.1-300 and 0.5-300 µM, respectively, with a limit of detection (LoD) of 3.12 and 8.7 nM, respectively. The levels of CLN in four selected tablet brands and CFL in two tablet brands were in the vicinity of 91.00-103.65% and 97.7-98.83%, respectively, of their nominal values. The recovery results for CLN in pharmaceutical samples were in the range of 99.00-100.67% and for CFL 97.9-99.75% and for blood serum and urine samples 99.55-100.55% and 99.33-100.34% for CLN and 97.13-100.60% and 96.73-102.50% for CFL, respectively. Interference recovery results with errors less than 4.81%, lower LoD, wider dynamic range, excellent recovery results, and good stability of the modifier compared to those for the previously reported methods validated the use of the poly(reso)/GCE for determining CLN and CFL simultaneously in various real samples.

Urinary 8-OHdG level is not affected by geography and trace elements in nail of residents of Addis Ababa: It is shaped by interactions between different social factors.

The objective of this study was to evaluate the association between exposure to heavy metals and oxidative DNA damage among residents living in the potentially more polluted downstream (Akaki-Kality) area of Addis Ababa, in comparison to the upstream area (Gullele). For this, 8-hydroxy-2'-deoxyguanosine (8-OHdG) was used as a biomarker for oxidative DNA damage and heavy metals (Fe, Zn, Mn, Cu, Ni, Cr, Pb, As) as indicators of exposure. The concentrations of heavy metals in nails were determined using inductively coupled plasma optical emission spectroscopy (ICP-OES), and 8-OHdG in urine using Enzyme-Linked with Immunosorbent Assay (ELISA), from 95 residents of the two areas, upstream and downstream. The urinary 8-OHdG concentration was not significantly different (p = 0.05) between the two Sub-Cities, with mean of 18.50 ± 4.37 ng/mg Creatinine in Akaki-Kality and 17.30 ± 5.83 ng/mg Creatinine in Gullele. Also, there were no statistically significant (p = 0.05) difference among the different demographic groups according to gender, age, educational status, body mass index or habit of alcohol consumption. However, the interactions of sex with age, sex with alcohol consumption and alcohol consumption with education were found to affect the urinary 8-OHdG levels of residents of the two Sub-Cities. The mean concentrations (µg/g) of the elements were 488 and 1035 for Fe, 106 and 251 for Zn, 13.0 and 31.2 for Mn, 5.23 and 6.63 for Cu, 11.2 and 7.39 for Ni, 2.23 and 2.02 for Cr, 0.09 and 0.63 for Pb; and 0.16 and 0.25 for As, in nail samples from Akaki-Kality and Gullele, respectively. The determined concentrations of the heavy metals in nails were not significantly associated (p = 0.05) with the corresponding urinary levels of 8-OHdG. Hence, the observed 8-OHdG might have been caused by environmental exposure to toxic substances other than the analyzed heavy metals.

Health risk assessment of heavy metals in selected Ethiopian spices.

A total of 144 spice samples (ajwain, black cumin, coriander and fenugreek) were collected from three districts. For the determination of heavy metals (Cd, Cr, Cu, Pb and Zn) concentrations and human health risks, the spice samples were digested in a mixture of HNO3 and HClO4. The highest concentrations of Cr (24.85 ± 1.673 mg/kg) and Cu (32.267 ± 7.355 mg/kg) were investigated in ajwain and Zn (54.13 ± 6.122 mg/kg) in fenugreek. However, lowest concentration of Cr and Cu were detected in fenugreek; and Zn in coriander. Cd and Pb were not detected in all spice samples. A positive correlation was observed among Cr, Cu and Zn in fenugreek; Zn with Cr and Cu in black cumin and Zn with Cu in ajwain and coriander. However, negative correlation was observed Cr with Cu and Zn in ajwain and coriander; Cr with Cu in black cumin. THQ values of Cu, Zn and 75% of Cr in all spices were less than 1. About 66.7% of the HI values of the samples under study were less than 1, indicated that the consumers will not experience potential health risks from the intake of individual metals through spices consumption.

Voltammetric determination of uric acid using multiwall carbon nanotubes coated-poly(4-amino-3-hydroxy naphthalene sulfonic acid) modified glassy carbon electrode.

In this study, an electrochemical sensor based multiwalled carbon nanotubes (MWCNTs)-poly (4-amino-3-hydroxy naphthalene sulfonic acid) modified glassy carbon electrode (MWCNTs/poly (AHNSA)/GCE) was developed for the determination of uric acid (UA). The composite electrode was prepared first by electropolymerization of the monomer (AHNSA) on GCE using cyclic voltammetry within the potential range of -0.8 V to +2.0 V vs Ag/AgCl for 15 cycles followed by drop coating of MWCNTs solution on the surface of poly (AHNSA)/GCE. Under optimal conditions, MWCNTs/poly (AHNSA)/GCE showed a linear current response with UA concentrations in the range of 1 × 10-6 to 1 × 10-4 M with R2 = 0.9972. The sensor exhibited low detection limit with a value of 0.024 µM. The sensors have been applied to successfully quantify UA in urine samples.

Levels of heavy metals in ginger (Zingiber officinale Roscoe) from selected districts of Central Gondar Zone, Ethiopia and associated health risk.

In this study, we investigated the concentrations of Cd, Cr, Cu, Fe, Ni, Pb and Zn; and their associated health risks through consumption of ginger. After the ginger samples digested with a mixture of HNO3 and HClO4 at 200 °C for 2:00 h, the amount of metals were investigated by flame atomic absorption spectrometry (FAAS). Efficiency of the analytical measurement was validated on spiking the sample with standard solutions of metals and the recovery for all studied metals were ranged from 91.60% to 99.94%, which is in the acceptable range of validation. The mean concentrations (mg/kg) were ranged from 4.63 to 5.43 for Cd, 2.17 to 4.44 for Cr, 62.52 to 65.14 for Cu, 77.71 to 81.12 for Fe, 6.49-7.58 for Ni and 16.74-19.31 for Zn. However, the concentration of Pb was not detected. The estimated daily intake (EDI) values of all metals from all samples are substantially lower than their corresponding maximum tolerable daily intake (MTDI). Target hazardous quotient (THQ) values of all metals are lower than 1 in all the sampling sites, revealed that there are no health risks for the users due to the intake of these metals. The health index (HI) values were slightly higher than unity, which implying that there is significant health effects to the population from consuming ginger at the study.

Electrochemical application of cobalt nanoparticles-polypyrrole composite modified electrode for the determination of phoxim.

In this study, cobalt nanoparticles (CoNPs) were synthesized and cobalt nanoparticles modified glassy carbon electrode (CoNPs/GCE) was prepared by drop coating the nanoparticles on glassy carbon electrode. After preparing polypyrrole modified glassy carbon electrode (PPy/GCE) using electropolymerization of pyrrole in LiClO4 solution, cobalt nanoparticles-polypyrrole composite modified glassy carbon electrode (CoNPs/PPy/GCE) was fabricated by drop coating the CoNPs on the PPy/GCE. Different characterization techniques such as scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, FTIR spectroscopy, electrochemical impedance spectroscopy and cyclic voltammetry were used to study the morphological structure and electrochemical behavior of the sensors. The results demonstrated that PPy chains interacted with CoNPs through donor-acceptor bonds. Among all the electrodes, CoNPs/PPy/GCE exhibited highest electroactive surface area and lowest electron transfer resistance towards phoxim. Under the optimal conditions, the sensor showed linear relationship between the reduction peak current and the concentration of phoxim in the range of 0.025 µM-12 µM with the detection limit as 4.5 nM. Besides, the composite electrode demonstrated excellent reproducibility, good stability and selectivity towards the possible interfering substances. All of these properties made CoNPs/PPy/GCE a suitable electrochemical sensor for the electrochemical determination of phoxim in water samples using square wave voltammetry.

Simultaneous determination of caffeine and paracetamol by square wave voltammetry at poly(4-amino-3-hydroxynaphthalene sulfonic acid)-modified glassy carbon electrode.

Poly(4-amino-3-hydroxynaphthalene sulfonic acid)-modified glassy carbon electrode (poly(AHNSA)/GCE) was prepared for simultaneous determination of caffeine and paracetamol using square-wave voltammetry. The method was used to study the effects of pH and scan rate on the voltammetric response of caffeine and paracetamol. Linear calibration curves in the range of 10-125µM were obtained for both caffeine and paracetamol in acetate buffer solution of pH 4.5 with a correlation coefficient of 0.9989 and 0.9986, respectively. The calculated detection limits (S/N=3) were 0.79µM for caffeine and 0.45µM for paracetamol. The effects of some interfering substances in the determination of caffeine and paracetamol were also studied and their interferences were found to be negligible which proved the selectivity of the modified electrode. The method was successfully applied for the quantitative determination of caffeine and paracetamol in Coca-Cola, Pepsi-Cola and tea samples.