Novel extractive colorimetric and UV spectrophotometric estimation of etizolam in bulk and tablet by forming ion association complex with methyl orange and bromocresol green

A novel, sensitive, and rapid UV spectrophotometric and colorimetric method was developed for estimation of etizolam (ETZ) in bulk and tablet. The UV spectrophotometric method (method I) is based on quantitative estimation of ETZ using 0.1N NaOH as the solvent which exhibits maximal absorption at 378 nm. Colorimetric methods (method II and III) were based on the formation of color complex in association with ions between basic nitrogen of the drug with methyl orange (MO) and bromocresol green (BCG) in acidic medium. The formed color complexes were quantitatively extracted with chloroform and measured at 509 nm for Drug–MO complex and at 442 nm for Drug–BCG complex, respectively. Beer's law was obeyed over the linear ranges 2–16 µg/ml (method I), 5–45 µg/ml (method II), and 2–20 µg/ml (method III). The correlation coefficient (r²) for ETZ was 0.999, 0.997, and 0.998 for method I, II, and III, respectively. All methods were successfully applied for the assay of the drug in tablet. The % purity was found to be 98.52 (method I), 98.72 (method II), and 99.18 (method III). These developed methods were fully validated with % relative standard deviation (RSD) for accuracy less than 2 for all methods. The % RSD of the intra-day and inter-day variations was found to be less than 2%. The limit of detection and quantitation were as follows: 0.108 µg/ml and 0.327 µg/ml (method I), 0.24 µg/ml and 0.75 µg/ml (method II), 0.1 µg/ml and 0.5 µg/ml (method III) indicating marked method sensitivity. Empirical evidence from all three methods concludes that developed methods are simple, sensitive, and reliably validated for useful routine quality control analysis of ETZ.     

Chloride migration in groundwater for a tannery belt in Southern India

Groundwater in a tannery belt in Southern India is being polluted by the discharge of untreated effluents from 80 operating tanneries. Total dissolved solids and chloride (Cl⁻) measurements in open wells in the tannery cluster vary from 27,686 to 39,100 and 12,000 to 13,652 mg/l, respectively. A mass transport model was constructed using Visual MODFLOW Premium 4.4 software to investigate the chloride migration in an area of 75.56 km². Input to the chloride migration model was a groundwater flow model that considered steady and transient conditions. This model was calibrated with field observations; and sensitivity analysis was carried out whereby model parameters, viz., conductivity, dispersivity, and source concentration were altered slightly, and the effect on calibration statistics was evaluated. Results indicated that hydraulic conductivity played a more sensitive role than did dispersivity. The Cl⁻ migration was mainly through advection rather than dispersion. It was found that even if the pollutant load reduced to 50% of the present level, the Cl⁻ concentration in groundwater, even after 6 years, would not be reduced to the permissible limit of drinking water in the tannery belt.     

Evaluation of groundwater resources in a tiny Andrott Island, Union Territory of Lakshadweep, India

Lakshadweep is a group of 36 coral islands scattered in the Arabian Sea off the western coast of India. On such small tiny islands, groundwater is the only source of fresh water for the islanders. Due to the growing population on these islands, demand for fresh water is also increasing and on the other side the peculiar hydrologic, geologic and geomorphic features restrict the availability of groundwater. Therefore, a proper understanding of the groundwater condition is important in order to meet this increasing demand and also to formulate future development and management strategies. Detailed hydrogeological, geophysical and hydrochemical studies have been carried out to identify potential fresh groundwater resources and quantify vulnerable parts of Andrott Island, Union Territory of Lakshadweep. Systematic collection and analysis of hydrological, geophysical and hydrochemical data reveal that fresh groundwater is only available between 2.5 to 5.0 m depths and provide an early sign of deterioration in groundwater quality in the peripheral parts of eastern and western coasts of this island. It suggests immediate measures for arresting the deterioration in groundwater quality as well as augmentation for restoration of aquifer in some parts of the island.     

Hair burning and liming in tanneries is a source of pollution by arsenic,lead, zinc,manganese and iron

Heavy metals in the environment may be toxic for human and animals. Tanneries are a source of pollution by heavy metals. There is little information on heavy metals pollution in tanneries, especially on metals produced by the process of hair burning and liming. Liming is the first stage of chemical treatment where animal hair or wool is removed with sodium sulphide and calcium oxide. Here we studied cow, goat, buffalo and sheep hair, conventional liming agents and liming wastewaters from several sources. Samples were acid-digested and aliquots were analysed by atomic absorption spectroscopy following APHA standard method to measure concentrations of arsenic, lead, cadmium, zinc, manganese and iron. Results show that the range of metal contents in hair or wool and liming agents are 1.3–8.2 mg/kg for arsenic, 0.02–21.8 mg/kg for lead, 17.7–121.0 mg/kg for manganese, 7.3–141.1 mg/kg for zinc and 119.6–10613.8 mg/kg for iron. Liming wastewaters contain 1.9–5.6 µg/L arsenic, 0.03–6.05 µg/L lead, 38.6–139.0 µg/L manganese, 144.0–171.5 µg/L zinc and 399.5–1069.0 µg/L iron. Cadmium was below detection limits. This is the first investigation that reveals that hair burning liming operation is a potential source of heavy metals in the environment.     

Purifying arsenic and fluoride-contaminated water by a novel graphene-based nanocomposite membrane of enhanced selectivity and sustained flux

Environmental Science and Pollution Research - A novel graphene-based nanocomposite membrane was synthesized by interfacial polymerization (IP) through chemical bonding of the graphene oxide (GO)...     

Predictability by Box-Behnken model for carbaryl adsorption by soils of Indian origin

This study was undertaken to investigate the adsorption capacity of carbaryl on four Indian soils with different physiochemical properties. A batch adsorption study was carried out in order to evaluate the maximum adsorption capacity of carbaryl using a Response Surface Methodology (RSM). The effects of operating parameter such as initial carbaryl concentration (1–20 mgL^?1), adsorbent dosage (0.5–6 g) and contact time (10–180 min) were examined. The proposed quadratic model for Box-Behnken design fits very well to the experimental data because it may be used to navigate design space according to ANOVA results. The regression co-efficient (R²) of the models developed and the results of validation experiments conducted at optimal conditions strongly suggests that the predicted values are in good agreement with experimental results. Contour and response surface plots are used to determine the interactions effects of main factors and optimal conditions of the process. The experiment can be utilized as a guideline for better understanding of carbaryl adsorption onto soil under different operating conditions. The results show that the forest soil is most efficient in binding carbaryl (Sevin) than the other types of soil tested.     

Uptake of chromium by Aspergillus foetidus

Aspergillus foetidus has the ability to take up chromium during the stationary phase of growth and under growth-nonsupportive conditions. We observed a 97% decrease in hexavalent chromium (initial concentration 5 µg/g) at the end of 92 h of growth, which may be due to its reduction to Cr (III) and/or complexation with organic compounds released due to the metabolic activity of the fungus. Replacement culture studies under growth-nonsupportive conditions revealed that the maximum uptake of Cr (VI) at pH 7.0 is 2 mg/g of dry biomass. At low or high pH values, Cr (VI) uptake is significantly reduced. In addition, the initial rate of total chromium uptake is also enhanced by higher biomass concentrations and the presence of glucose. The results obtained through this investigation indicate the possibility of treating waste effluents containing hexavalent chromium using Aspergillus foetidus.     

Study on the Physico-mechanical Properties of Photo-cured Chitosan Films with Oligomer and Acrylate Monomer

Chitosan films were prepared from dried prawn shell via chitin and then tensile properties like tensile strength (TS) and elongation at break (Eb) of the films were evaluated. Six formulations were developed using methyl methacylate (MMA) monomer and aliphatic urethane diacrylate oligomer (M-1200) in methanol along with photoinitator (Darocur-1664). Then the films were soaked in the formulations and irradiated under UV radiation at different doses for the improvement of physico-mechanical properties of chitosan films. The cured films were characterized by measuring TS, Eb, polymer loading (PL), water absorption and gel content properties. The formulation containing 43% MMA and 15% oligomer in methanol solution showed the best performance at 20th UV pass for 4 min soaking time.     

Toxicity of cadmium nanoparticles to Bacillus subtilis

The study deals with the toxicological impact of cadmium nanoparticles (Cd NPs) on Bacillus subtilis as a model Gram-positive bacterium. Cadmium oxide (CdO) NPs (～22 nm) and cadmium sulfide (CdS) NPs (～3 nm) were used in this study. Both the NPs were found to inhibit the cell viability of B. subtilis when added to the culture at mid-log phase, the viable cell number declined with increasing concentration of Cd NPs. At mid-log phase, 15 mg L^?1 CdO NPs inhibited growth by ～50%, whereas at 30 mg L^?1 growth completely ceased. Under the same conditions, CdS NPs inhibited growth by ～50% at a concentration of 8 mg L^?1, and at 20 mg L^?1 growth was completely retarded. The cells changed their morphological features to a filamentous form with increasing Cd NPs exposure time, leading to associated with clumping. NPs treated cells when stained with 4′, 6-diamino-2-phenylindole, showed filamentous multinucleated bead structure, suggesting irregularities in cell division. Increasing intracellular oxidative stress due to Cd NPs exposure might be one of the reasons for the cell morphological changes and toxicity in B. subtilis.