Sangita D. Kumar

Permeation of inorganic anions through Nafion ionomer membrane

Permeation of different inorganic anions, namely, F−, Cl−, Br−, NO2−, NO3− and SO42− through NafionTM 117 ionomer membrane has been studied as a function of pH and salt concentrations in feed solution. At low pH, fluoride and nitrite ions showed higher permeation than other anions. This has been attributed to a higher association of HF and HNO2 in the membrane phase. Easy diffusion of the undissociated acids and their subsequent permeation has been explained on the basis of the morphology of the ionomer. The lowering of anion transport in the presence of different cations has been attributed to the complex formation of the anions with these cations.

A fluoride ion selective Zr(IV)-poly(acrylamide) magnetic composite

A fluoride ion selective magnetic sorbent has been synthesized by the encapsulation of Fe3O4 nanoparticles in a network of Zr(IV) complexed poly(acrylamide) (Zr–PAM). This magnetic sorbent has been found to be efficient for the selective preconcentration of fluoride ions from natural waters. The Zr–PAM/Fe3O4 composite has been characterized using various physico-chemical techniques i.e. energy dispersive X-ray fluorescence (EDXRF), scanning electron microscopy (SEM), Fourier transform infra-red spectroscopy (FTIR) and a vibrating sample magnetometer (VSM). The Zr–PAM/Fe3O4 composite developed in the present work retains the super paramagnetic properties of Fe3O4 nanoparticles, and the results reveal that the sorption is rapid. The composite has a considerably higher fluoride sorption capacity (124.5 mg g−1) compared to other super-paramagnetic fluoride sorbents reported in the literature. Repeated sorption–regeneration cycles seem to suggest reusability of the sorbent for fluoride removal from natural waters, as well as other aqueous solutions having pH in the range 1–9.

Extractive fixed-site polymer sorbent for selective boron removal from natural water.

Water contamination by boron is a widespread environmental problem. The World Health Organization (WHO) recommends maximum boron concentration of 2.4 mg L(-1) for drinking water. The paper presents a simple method for preparation of functionalized sheet sorbent for selective extraction of boron from natural water. The pores of commercially available poly(propylene) membrane were functionalized by room temperature in situ crosslinking of poly(vinylbenzyl chloride) with a cyclic diamine piperazine. The precursor membranes were chemically modified with N-methyl D-glucamine which is selective for boron. Characterization of membrane was carried out using scanning electron microscopy (SEM) and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) techniques. The functionalized membrane has been characterized in terms of parameters that influence the sorption of boron from aqueous streams like pH, uptake capacity, contact time, effects of competing ions and reusability. The maximum boron sorption capacity determined experimentally was 28 mg g(-1). The studies showed that trace concentrations of boron were quantitatively removed from water at neutral pH. The developed fixed site polymer sorbent exhibited high sorption capacity and fast kinetics as compared to various sorbents reported in literature. It was successfully applied for the removal of boron from ground water and seawater samples in presence of high concentration of interfering ions.

Whole blood glucose determination using glucose oxidase immobilized on cotton cheese cloth

Abstract An amperometric biosensor for glucose, which uses a novel matrix, namely cotton cheese cloth, for the immobilization of glucose oxidase (GOD) enzyme is described. The immobilized GOD has been found to be very stable and the performance characteristics of the proposed biosensor are found to be better than those of the existing glucose sensors. The response of the sensor is linear to glucose concentration over the range 10 −3 2 × 10 −2 mol , the range being normally encountered in human blood. Results for glucose in diluted whole blood samples are in good agreement with those obtained with standard colorimetric method followed by clinical laboratories.

Synthesis of alkynyl/alkenyl-substituted pyridine derivatives via heterocyclization and Pd-mediated Sonogashira/Heck coupling process in one-pot: a new MCR strategy

A new class of 2-amino-4-(3/2-(alkynyl)/3-(alkenyl)phenyl)-6-phenylnicotinonitriles (6, 7 & 9) has been synthesized with good to excellent isolated yields by the multi-component reaction (MCR) of bromobenzaldehyde (1), malononitrile (2), acetophenone (3), NH4OAc (4) and a series of terminal alkynes (5)/alkenes (8) in the presence of pyrrolidine and Pd-catalyst in a mixture of H2O–DME (1 : 4 ratio) under reflux conditions in a single step. The Heck-type coupling with terminal olefins takes place stereoselectively with exclusive formation of E-isomers. This new MCR strategy opens new avenues in the development of (i) a diversity-oriented new cyanopyridine based compound library and (ii) new chemical entities other than the present reported molecules.

Matrix supported tailored polymer for solid phase extraction of fluoride from variety of aqueous streams

Fluoride related health hazards (fluorosis) are a major environmental problem in many regions of the world. It affects teeth; skeleton and its accumulation over a long period can lead to changes in the DNA structure. It is thus absolutely essential to bring down the fluoride levels to acceptable limits. Here, we present a new inorganic-organic hybrid polymer sorbent having tailored fixed-sites for fluoride sorption. The matrix supported poly (bis[2-(methacryloyloxy)-ethyl]phosphate) was prepared by photo-initiator induced graft-polymerization in fibrous and microporous (sheet) host poly(propylene) substrates. These substrates were conditioned for selective fluoride sorption by forming thorium complex with phosphate groups on bis[2-methacryloyloxy)-ethyl] phosphate (MEP). These tailored sorbents were studied for their selectivity towards fluoride in aqueous media having different chemical conditions. The fibrous sorbent was found to take up fluoride with a faster rate (15 min for ≈76% sorption) than the sheet sorbent. But, the fluoride loading capacity of sheet sorbent (4,320 mg kg(-1)), was higher than fibrous and any other sorbent reported in the literature so far. The sorbent developed in the present work was found to be reusable after desorption of fluoride using NaOH solution. It was tested for solid phase extraction of fluoride from natural water samples.

Functionalized polymer sheet sorbent for selective preconcentration and determination of mercury in natural waters

Mercury is considered as a highly toxic and widespread heavy-metal pollutant. In the present work, two flat-sheet polymer sorbents have been synthesized for the selective preconcentration of mercury from natural waters. These are a silver nanoparticle (AgNP)-embedded poly(acrylamide)-grafted poly(propylene) sheet (Ag-PAM-PP) and a 1,8-octanedithiol-functionalized gold-coated poly(propylene) sheet (HS-octyl-S-Au-PP). The functional groups acrylamide and thiol provide the binding sites for Hg2+ ions; whereas silver nanoparticles reduce Hg2+ to Hg0 and it is held on the sheet by amalgam formation. Various factors that influence the preconcentration of Hg2+ from aqueous solution were investigated. Based on the comparison of the experimental results, it was observed that Ag-PAM-PP had superior performance for uptake of Hg2+ from natural water samples in terms of sorption capacity, sorption kinetics and working pH range. The uptake of Hg2+was found to be pH dependent with a maximum of 95% at pH 7.5. The preconcentration of Hg2+ from a large volume of aqueous solution was used to extend the lower limit of the concentration range that can be quantified by EDXRF and CV-AAS. The sorbed Hg(II) from aqueous samples was quantitatively detected within 1 min using EDXRF. The LOD (3σ) for CV-AAS (RSD = 2%) and EDXRF (RSD = 5%) were 6 and 30 μg L−1, respectively. The method was applied for the determination of Hg2+ in groundwater and seawater samples in the presence of a high concentration of interfering ions.

Application of Ion Chromatography for the Determination of Nitrate in Process Streams of Thermal Denitration Plant

A simple, accurate, and rapid analytical methodology for the determination of nitrate content in process streams of thermal denitration plant has been developed. The nitrate content in these process streams varies over a wide range of concentration (0.1–150 g L−1). Quantitative determination of nitrate was accomplished by anion exchange chromatography with conductometric detection in suppressed mode. The method requires a simple sample dilution step. A Metrosep A supp 3 analytical column connected in series with a Metrosep RP guard column was used for nitrate separation. A solution containing a mixture of 1.8 mM Na2CO3 and 1.7 mM NaHCO3 was used as eluent. The limit of detection for the determination of nitrate is 0.02 µg mL−1 and the relative standard deviation was 5% for the overall method. No interference was observed from either the chloride or closely eluting “system peak” in the determination of nitrate. The method was validated using an ion selective electrode based determination. The method has a high throughput and 6 samples were analyzed per hour to provide the data on the process parameters. No interference was observed from the other anionic impurities, namely chloride and sulphate. In the case of process streams from thermal denitration of Zr raffinate the method requires a sample pretreatment for the removal of large excess of zirconium from the sample matrix. Onguard-H cartridges were found most suitable for this purpose. The concentration of different anions could be measured simultaneously.

Acute renal failure secondary to ingestion of alternative medication in a patient with breast cancer.

Complementary and alternative medicine (CAM) use among cancer patients is widely prevalent and often underreported. Advanced stage of disease is significantly associated with CAM use. The concurrent use of alternative medicines and chemotherapy drugs has the potential to lead to toxicities as well as altered therapeutic activity due to unknown interactions. We report a case of early breast cancer who presented to us with non-oliguric acute renal failure related concurrent use of Ayurvedic medicines and adjuvant anthracycline based.

Characterisation of graphite using boron as a marker element

Graphite has many industrial applications. Two of the most important applications are as electrodes in industries and as moderator in nuclear industry. Determination of the Boron Equivalent of the impurity elements in graphite is the most important parameter for certifying the grade of graphite electrode [1]. The use of a suitable method with low limits of determination of boron is therefore necessary. A method has been standardised in Analytical Chemistry Division, BARC for determining trace amounts of boron in graphite electrodes. It involves controlled dissolution of graphite sample powder and measurement of boron by Inductively Coupled Plasma Mass Spectrometer (ICP-MS) using matrix matched standards. The method detection limit is 1 μg g−1. The method Relative Standard Deviation was 5%. The method was verified by spike recovery experiments. Recoveries were found to be within 100±2% in the concentration range of 1 to 100 μg g−1. The developed method has been adopted for the compositional characterizatio...