Detection of selenium in environmental samples, inorganic mixtures, and a specific method for its gravemetric analysis

A novel compound, i.c. malonyl dihydrazide (MDH) was synthesized by coupling of diethylmalonate and hydrazine hydrate in alcoholic medium. The reagent is applied for the field test detection of Se, and garvimetric analysis of Se and Te in various real samples, i.e. sediment, waste-water, cigarette paper, cabbage, etc. A drop of sample containing more than 2 and 6 $\mu$g of Se on test-tube/plate and test-paper were found to be detected, respectively. The reagent is successfully applied for the detection of Se and Te in semi-micro analysis of inorganic mixtures containing different ions. The gravimetric determination of Se and Te is highly selective, as the analysis conditions are different for both the elements. The non-stick precipitates also having good filtration characteristics, therefore 5 mg Se or Te present in the solution can be estimated accurately. Almost an metal ions associated with real samples did not interfere. The detection and determination with the proposed reagent is simple, rapid, selective and sensitive in comparison to other conventional methods. The data of estimation of Se and Te in standard samples prove the reliability of the proposed gravimetric determination

Dominance of lithogenic effect for nickel, cobalt, chromium and mercury as found in freshly deposited sediments of the river Subernarekha, India

The importance of study of heavy metal distribution in river sediments is a component in understanding the exogenic cycling as well as in assessing the effect of anthropogenic influences of the elements. In India, the river Subernarekha flows over Precambrian terrain of Singhbhum craton in the eastern India. The geological succession in this part of India is through (1) iron ore series, (2) ultrabasic igneous rocks, (3) diorite, (4) granite, (5) newer dolerites, (6) newer tertiary and (7) alluvium. The first four groups belong to the Archaean era, and the representative is the iron ore series consisting of iron ore, manganese and chromite which are abundantly present. The primary rock types are schist and quartzite layers. One main tributary, the Kharkhai flow through granite and schist and quartzite layers. Two important creeks are Gurma and Garra, respectively. The former after originating in basic igneous area travels through schist quartzite, while the later one originates in granite area where some functional but old gold mines are located. Freshly deposited sediments of river were collected upstream and downstream the industrial zone (East Singhbhum district). Samples were collected from four locations and analysed in <63 μm sediment fraction for heavy metals like Ni, Co and Cr by adsorption stripping voltammetry on hanging mercury drop electrode and Hg by anodic stripping voltammetry using polished rotating gold disk electrode. Enrichment of these metals over and above the local natural concentration level (NCL) has been calculated and applied to determine metal-pollution index (MPI) proposed by Goncalves et al. and also geo-accumulation index (I geo) by Muller. Based on Muller’s classification, Ni, Cr and Hg have been classified from unpolluted to moderately polluted range in pre-monsoon period but for metals Ni and Cr, during the post-monsoon period the values have reached moderately polluted level while Hg has been classified under unpolluted to moderately polluted level except at the monitoring station situated upstream to Gurma Creek where it was found at unpolluted level. Presence of natural resources of the minerals is primarily the reason for their detection in river sediments (lithogenic) but some anthropogenic sources are also contributing for their presence at some sampling stations. Hg is considered to be chalcophilic in nature and is detected wherever known sulphidic ores of copper or nickel are present

Heavy metals in freshly deposited sediments of the river Subernarekha, India: an example of lithogenic and anthropogenic effects

Heavy metal distribution patterns in river sediments aid in understanding the exogenic cycling of elements as well as in assessing the effect of anthropogenic influences. In India, the Subernarekha river flows over the Precambrian terrain of the Singhbhum craton in eastern India. The rocks are of an iron ore series and the primary rock types are schist and quartzite. One main tributary, the Kharkhai, flows through granite rocks and subsequently flows through the schist and quartzite layers. The Subernarekha flows through the East Singhbhum district, which is one of India’s industrialised areas known for ore mining, steel production, power generation, cement production and other related activities. Freshly deposited river sediments were collected upstream and downstream the industrial zone. Samples were collected from four locations and analysed in <63-μm sediment fraction for heavy metals including Zn, Pb, Cd and Cu by anodic stripping voltammetry. Enrichment of these elements over and above the local natural concentration level has been calculated and reported. Sediments of the present study are classified by Muller’s geo-accumulation index (I geo) and vary from element to element and with climatic seasons. During pre-monsoon period the maximum I geo value for Zn is moderately to highly polluted and for Cu and Pb is moderately polluted, respectively, based on the Muller’s standard. Anthropogenic, lithogenic or cumulative effects of both components are the main reasons for such variations in I geo values. The basic igneous rock layer through which the river flows or a seasonal rivulet that joins with the main river may be the primary source for lithogenic components

Kinetic study of hydrolytic decomposition of organophosphates and thiophosphate by N-hydroxyamides in cationic micellar media<b></b>

726-730The nucleophilic hydrolytic reactions of p-nitrophenyl diphenyl phosphate (PNPDPP), p-nitrophenyl diethyl phosphate (Paraoxon) and p-nitrophenyl diethyl phosphorothioate (Parathion) with N-hydroxyamides have been investigated at 27 °C. With cationic micelles, rate enhancement has been observed on the nucleophilic attack at P center. All the rate surfactant profiles show typical micelle assisted bimolecular reactions. The interfacial ion exchange, control of the interfacial nucleophile concentration and the reactivity at the micellar interface has been explained

Expression of glutathione-S-transferase and its role in plant growth and development in vivo and shoot morphogenesis in vitro

10.1007/s11103-004-4516-1Plant Molecular Biology57153-66PMBI