Application of NMI-TfCl-mediated amide bond formation in the synthesis of biologically relevant oxadiazole derivatives employing less basic (hetero)aryl amines.

We herein report a modified methodology for the synthesis of some oxadiazoles linked to amides under mild conditions. The developed protocol using NMI-TfCl has been found to be effective and tolerant for the amide bond formation reaction of a series of electronically deactivating and sterically challenging amines. The antioxidant potential of the newly synthesized compounds has been evaluated at the later stage.

Preparation of H3PO4 modified Sidr biochar for the enhanced removal of ciprofloxacin from water.

In this study, biochar was prepared from Sidr plant leaves and used for the treatment of ciprofloxacin (CIP)-contaminated water. CIP is important class of emerging water pollutants from pharmaceutical industries. The biochar showed 65% adsorption efficiency and 43.48 mg/g adsorption capacity of CIP. Adsorption efficiency as well as adsorption capacity were improved to 91% and 62.50 mg/g, respectively, by phosphoric acid (H3PO4) modified biochar. Removal of CIP by the prepared biochar was due to different surface functional groups of CIP and biochar as revealed from the study of different characterization analyses. The presence of PO43- group in modified biochar led to maximum binding of CIP. Also, the modified biochar showed higher reusability potential and less leaching of ions when compared to the raw biochar. Removal of CIP was affected by concentrations of CIP, the amount of biochar and different pH's; the maximum removal of CIP was achieved at pH 4. The Freundlich and pseudo-first-order models best fitted the removal of CIP by modified biochar. Advanced characterization techniques were applied to investigate surface and physiological characteristics of the biochar and modified biochar. The modification showed high impact on the performance and stability of biochar. The study showed significant impacts of modification on the potential of the biochar for treatment of CIP-contaminated water.

Changes in the Invasion Rate of Prosopis juliflora and Its Impact on Depletion of Groundwater in the Northern Part of the United Arab Emirates.

Prosopis species were introduced to the United Arab Emirates (UAE) region for desert greening. However, the species now pose a great threat to the native plant diversity. This study used high-resolution satellite imagery (1990-2019) to understand the history and current distribution of Prosopis species and their impact on fresh groundwater. The results show that the Prosopis invasion in the study area reached its maximum expansion rate in 2019 and covered an area of about 16 km2 compared to 0.2 km2 in 1990. The areas near Sharjah Airport, Umm Fannan, and Al Talla, located at a lower elevation of the sand dune area, are heavily invaded. Prosopis groundwater requirement derived using evapotranspiration shows that groundwater consumption has changed drastically after 2010 and consumed about 22.22 million m3 of groundwater in 2019, which is about a 7372% increase in groundwater consumption from the year 1990 to 2019. The results can be useful for setting up a management plan for the sustainable use of this species in the UAE region in particular and other similar countries in the arid land regions that are suffering from freshwater depletion because of Prosopis invasion.

Assessment of Metals Concentrations in Soils of Abu Dhabi Emirate Using Pollution Indices and Multivariate Statistics.

The aim of this study was twofold. Firstly, we performed a land capability class determination of the agricultural soils from the Abu Dhabi Emirate, the United Arab Emirates, based on the concentrations of 17 chemical elements determined in the soil samples collected from 84 locations. Secondly, we assess the soil pollution with different metals, using several pollution indices. The results of Principal Component Analysis (PCA) shows that four principal components (PCs) are responsible for describing the total metals concentrations' variance, the highest contribution on PC1 being that of Mn, and Cr, on PC2 that of Fe, on PC3 that of Cu, and on PC4 that of Al. After determining the optimal number of clusters, we classified the sites into three clusters, while the studied metals were grouped function on their concentrations. Then, we used five indices to assess the pollution level of the soil at the study sites and in the clusters. The geo-accumulation index (Igeo) indicates uncontamination/moderately contamination with Cu in cluster 1, uncontaminated/moderately contaminate soils with Cd, Cu, and Ni in cluster 2, and uncontaminated/moderately contaminated soil with Cu and moderately contaminated with Pb, Zn, and Ni in cluster 3. By comparison, the enrichment factors overestimate the pollution of the studied sites. The pollution load index (PLI) indicates a baseline level of pollution at 14 sites and the deterioration of the soil quality at four sites. The Nemerow pollution index provides similar results as PLI.

Contamination Assessment of Heavy Metals in Agricultural Soil, in the Liwa Area (UAE).

The Liwa area is a primary food production area in the United Arab Emirates (UAE) and has intensively been used for agriculture. This study investigates the pollution levels with heavy metals in agricultural soils from the Liwa area. Thirty-two soil samples were analyzed for Mn, Zn, Cr, Ni, Cu, Pb, Cd, Co, and As. Results revealed that heavy metal levels varied in the ranges 220.02-311.21, 42.39-66.92, 43.43-71.55, 32.86-52.12, 10.29-21.70, 2.83-8.84, 0.46-0.69, 0.03-0.37 mg/kg for Mn, Zn, Cr, Ni, Cu, Pb, Cd, Co, and As, respectively. All samples presented low As concentrations with an average of 0.01 mg/kg. The variations in bulk metal contents in the soil samples were related to multiple sources, including agrochemicals, atmospheric dust containing heavy metals, and traffic-related metals. Enrichment factor analysis indicates that Cd, Ni, Zn, and Cr were highly enriched in soils, and they could originate from non-crustal sources. Based on the geo-accumulation index (Igeo), the soil samples appeared uncontaminated with Mn, Cr, Zn, Pb, Co, As, Cu, uncontaminated to moderately contaminated with Ni and moderately contaminated with Cd. The contamination factors suggest low contamination, except for Ni, which showed moderate contamination. The average pollution load index (PLI) revealed unpolluted to low pollution of all soil samples. The ecological risk assessment (PERI) showed that all heavy metals posed a low risk, except for Cd which exhibited a high ecological risk.

Identification, characterization and quantification of a new impurity in deferasirox active pharmaceutical ingredient by LC-ESI-QT/MS/MS.

An unknown impurity was detected in deferasirox drug substance by a newly developed high performance liquid chromatography (HPLC) method. The unknown impurity was identified by liquid chromatography-tandem mass spectrometry using electrospray ionization source and Q-trap mass analyzer (LC-ESI-QT/MS/MS). Based on LC-MS/MS data and knowledge of the synthetic scheme of deferasirox, this impurity was proposed as the regio-isomer of deferasirox. Structural confirmation of this impurity was unambiguously carried out by synthesis followed by characterization using nuclear magnetic resonance (NMR), infrared spectroscopy (IR), mass spectrometry, elemental analysis (EA) and the impurity was confirmed as 2-[3,5-bis(2-hydroxy-phenyl)-[1,2,4]-triazol-1-yl]-benzoic acid (Imp-1). The newly developed method was validated according to ICH guidelines. The resolution between Imp-1 and deferasirox was found to be more than 6.0 and the detection limit of impurities was in the range of 0.0005-0.01%, indicating high selectivity and sensitivity of the newly developed method.

Use of two sulfonthalein dyes in the extraction-free spectrophotometric assay of tramadol in dosage forms and in spiked human urine based on ion-pair reaction.

Tramadol is a centrally acting analgesic used in the prevention and treatment of moderate to severe pain. Two sensitive, selective, and rapid spectrophotometric methods are described for the determination of tramadol in its dosage forms and in spiked human urine. The methods are based on formation of yellow ion-pairs between tramadol and two sulfonthalein dyes; bromocresol purple (BCP) and bromocresol green (BCG) in dichloromethane medium followed by absorbance measurement at 400 and 410 nm, respectively. Under the optimum conditions, tramadol could be assayed in the concentration ranges, 1-15 and 1-16 µg ml(-1) with correlation coefficient greater than 0.999 in both cases. The molar absorptivity values are calculated to be 1.84 × 10(4) and 1.97 × 10(4) l mol(-1) cm(-1) for BCP and BCG methods, respectively; and the corresponding Sandell sensitivity values are 0.0143 and 0.0134 µg cm(-2). The limits of detection (LOD) and quantification (LOQ) have also been reported. The stoichiometry of the reaction was found to be 1:1 in both cases and the conditional stability constant (K(f)) values of the ion pairs have been calculated. The within-day and between-day RSD were 0.9-1.96% and 1.56-3.21%, respectively. The methods were successfully applied to the determination of tramadol in tablets and injections and also in spiked human urine with good recoveries. The procedures are simple, accurate, and suitable for quality control application.