Revista de química analítica ambiental

Vegetables constitute essential diet components by contributing carbohydrates, proteins, vitamins, iron, calcium and other nutrients that are in short supply. The present study was conducted to evaluate vegetables such as leafy (spinach), melon (gourd, long gourd and pumpkin) and solonaceous (brinjal) for their potential to accumulate different heavy metals like Cadmium (Cd), Manganese (Mn), Chromium (Cr), Copper (Cu), Iron (Fe), Nickel (Ni), Lead (Pb) and Zinc (Zn). The content of these metals was measured by using Atomic Absorption Spectrophotometer. Mean values were recorded against each vegetable for accumulating heavy metals. It was observed that maximum concentration of Mn (137.3 mg/kg), Cr (6.62 mg/kg) and Fe (968.25 mg/kg) was found in spinach, exceeding the allowed threshold 2.2 mg/kg, 2.3 mg/kg and 425 mg/kg respectively, as set by WHO/FAO. While melon showed great potential to absorb Ni (5.05 mg/kg) which elevated safe limit 0.1 mg/kg and Cu (65 mg/kg) was within the safe range. Brinjal displayed maximum absorption of Zn (41 mg/kg), which did not cross the WHO reference limit 73 mg/kg. In case of Cd both gourd and brinjal showed equal concentration of 0.39 mg/kg but was not at the safe limit 0.241 mg/kg. However levels of Pb were below the FAO/WHO recommended limits in all the vegetables. Low concentrations of Pb indicate that these plants contribute less toxic effects of metals. Overall this order of absorption was recorded as leafy˃melon˃solonaceous. Human DIM has also been computed and was observed below recommended values by the FAO/WHO. However, to prevent any chronic health risk and extent of heavy metal contamination, steps must be taken to reduce human activities at the sites. Regular monitoring of heavy metals in the vegetables grown in wastewater irrigated areas is also necessary.

A novel bisfluoro monomer was synthesized in two steps:

1) 9-ethylcarbazoleobtained obtained from 9H-Carbazole and 1-bromoethane, and

2) a new 3, 6-bis-4-fluorobenzoyl-9-ethylcarbazole monomer was obtained from 9-ethylcarbazole and 4- fluorobenzoylchloride; it was then used to prepare novel Poly (Arylene Ether Ketone)s (PAEKs). FTIR and 1HNMR methods were used to characterize the synthesized monomers and polymers. Further, solubility tests showed that PAEKs were generally soluble in a wide range of solvents including Dimethyl Acetamide (DMAc), NMethylpyrrolidone (NMP), Dimethyl Sulfoxide (DMSO) and H2SO4. Thermo Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) indicate that the synthesized PAEKs showed only 10% weight loss in air up to 410°C and were essentially amorphous.

Background: Semiconductor Quantum Dots (QDs) have gained much attention in different fields of application due to exclusive photochemical reactions. They achieved a big triumph in supramolecular chemistry. A highly sensitive and specific nanosensor was reported in this study using QDs coated with acid for sensing Heavy Metal (HM) ions in water. Few relevant patents to the topic have been reviewed and cited in this article.
Methods: The Mercaptopropionic Acid (MPA)-capped CdTe QDs were prepared through a hydrothermal route and characterized by TEM, FTIR, UV/Vis, fluorescence and XRD techniques. Sensing of HM ions was performed in Deionized Water (DW) by titration of their respective salts with CdTe/MPA.
Results: TEM revealed that the QDs size diameter was in the range of 4 ± 0.2 nm. FTIR, UV/Vis, and fluorescence confirmed the structure and spectroscopic classification of QDs. XRD showed that CdTe/MPA crystals were cubic. Based on the fact that the QDs fluorescence possibly quench by HM ions, an easy process for HM detection was anticipated. The QDs response showed a direct correlation to the concentration of HM. The synthesized QDs had potential for detecting the HM ions with higher selectivity to Mercury ions (Hg2+) in water compared with Lead (Pb2+) and Barium (Ba2+). The optimum sensor sensitivity was achieved at pH 8.
Conclusion: HM ions quenching CdTe/MPA fluorescence in a concentration-dependent manner. The method presented in this manuscript is novel, economical and convenient for realistic applications.

In this study, Cr2O3/TiO2 nanoparticles were synthesized using sol-gel method. TiO2 as one of the most important semiconductor materials with a variety of applications in many fields including photocatalysis and solar cells combined with Cr2O3 as a mineral material and one of the basic oxides used as pigments to improve properties such as mechanical strength, thermal stability form the Cr2O3/TiO2 nanocomposite showing attractive applications in photocatalysis and solar cells. To this end, its application in solar cells has been investigated to testify its performance. The results were promising in the case of solar cell. Cr2O3/TiO2 nanocomposite solution formed a compact layer with low defects and grain boundaries while it was sprayed as blocking layer (TiO2) in superstrate structure CZTS solar cells (Glass/FTO/TiO2/In2S3/CZTS/carbon). Compared to individual TiO2 blocking layer, the asdeposited layer showed better quality and performance. X-Ray was used to confirm synthesized nanoparticles and their morphology was investigated by Field-Emission Scanning Electron Microscopy (FE-SEM).

In the context of increasing uses of Arsenic contaminated groundwater for irrigation in Bangladesh and observed health related problems, we evaluated potential health risk for Bangladesh is due to As exposure from consumption of vegetables. Eight vegetable plants (Amaranth, Arum, Carrot, Eggplant, Indian Spinach, Okra, Potato and Radish) were grown in open field and irrigated with natural As contaminated water (0.005-0.903 mg L-1) for 80-90 days. The average As concentrations in the vegetables, measured by GF-AAS, were 0.431, 0.719, 0.928, 1.574 and 2.287 mg kg-1 (ww.) corresponding to irrigation water As concentrations of 0.005 (control), 0.044, 0.103, 0.507 and 0.903 mg L-1 respectively. We established linear regression equation of fitted model for water-vegetable As concentration (n=54) relationship (r=0.767 and P<0.05). Statistical analyses with r value, P value of ANOVA table, Durbin-Watson Statistic and Lack-of-Fit test strongly validated the model. Merging British Geological Survey’s (BGS) groundwater datasets (n=3534) for Bangladesh to the model led to estimation of As concentrations in vegetables district-wise. We followed USEPA Guidelines for Exposure Assessment for evaluation of human health risk. Risk, defined as ‘Hazard Quotient’ (HQ), was mapped for three vulnerable population sub-groups: Highly Exposed Child, Average Person and Senior. The results showed that all the children (0-6 years) were at health risk, whereas 98% of seniors and 76% of average persons (i.e., adults) were safe in consuming vegetables. The eight administrative division-wise HQ values for average persons were as follows: Rangpur (0.760)pollutant parameters.