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Purnendu K. Dasgupta

Bio: Purnendu K. Dasgupta is an academic researcher from University of Texas at Arlington. The author has contributed to research in topics: Ion chromatography & Detection limit. The author has an hindex of 62, co-authored 506 publications receiving 16779 citations. Previous affiliations of Purnendu K. Dasgupta include Dow Chemical Company & Texas Tech University.


Papers
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Patent
31 May 1995
TL;DR: In this article, a conductive membrane connects a second capillary to a second power supply, which act together as an auxiliary EC pump capable of augmenting or inhibiting the bulk electroosmotic flow in the separation capillary.
Abstract: Apparatus for capillary electrophoresis having an auxiliary electroosmotic pump. Following a conventional capillary electrophoresis system having a single power supply, a separation capillary, and an optical detector, a conductive membrane connects a second capillary to a second power supply. The second capillary and second power supply act together as an auxiliary electroosmotic pump capable of augmenting or inhibiting the bulk electroosmotic flow in the separation capillary. The apparatus can be used to optimize the stacking profile of the sample and, thus, improve the separation efficiencies for charged solutes.

18 citations

Patent
01 Aug 1997
TL;DR: In this paper, a separation capillary with a first distal tip (30) and a second distal point (140) was used for electrophoresis of a microreservoir-electrode.
Abstract: A capillary electrophoresis system (10) comprising: a separation capillary (20) with a first distal tip (30) and a second distal tip (140); a source vessel (50) containing a solution (40); a microreservoir-electrode (59) comprising a wire loop; a power source (60) connected to the microreservoir-electrode by wire (57); a control system (200); a detector (90); and a final destination vessel (160) containing electrolyte (150) and a ground electrode (155).

18 citations

Journal ArticleDOI
TL;DR: In this paper, peroxide was found to be produced as artifacts during cryogenic sampling with Horibe traps, and the amount of artifact H2O2 and HMHP increased with decreasing trap temperature.
Abstract: Peroxides were found to be produced as artifacts during cryogenic sampling with Horibe traps. Cryogenic trap sampling was compared to collection with a wet effluent diffusion denuder and a Nafion membrane diffusion denuder. Hydrogen peroxide and hydroxymethyl hydroperoxide measured in the cryogenic trap samples were significantly higher. In comparison, no evidence of artifact methyl hydroperoxide production was found. The amount of artifact H2O2 and HMHP produced increased with decreasing trap temperature. Spiking ambient air with ethene or isoprene showed that these hydrocarbons, in the presence of ozone, can be responsible for the artifact production of peroxides. Our results clearly suggest that the peroxide data obtained by cryogenic sampling and reported in the literature should be interpreted with caution.

17 citations

Journal ArticleDOI
TL;DR: Ion Chromatographie determination of S(IV) is described with special reference to the determination of SO 2 (g) and/or aerosol S (IV) along with chloride, nitrate and sulfate in particulate matter as mentioned in this paper.

17 citations

Patent
03 Apr 2002
TL;DR: In this paper, the authors present a flow cell and a method for analyzing fluid-fluid and fluid-solid interactions in a substantially planar system, which allows the simultaneous manipulation of different fluids on a small planar surface.
Abstract: The present invention provides a method of performing analyses and assays involving multiple interactions of reagent-containing fluid flows with liquid and solid target substances. The methods of the invention allow the simultaneous manipulation of different fluids on a small planar surface. The invention also provides a flow cell and method of use thereof for analyzing fluid-fluid and fluid-solid interactions in a substantially planar system. The flow cell contains at least one chamber and a plurality of inlets thereto allowing the introduction of a plurality of fluids in fluidic contact. The cell depth is the smallest dimension of the flow cell, and is of a magnitude, from about 50 to about 1000 microns such that any mixing of adjacent fluids in the chamber is substantially limited to mixing by passive diffusion. Interactions between reagents in fluids and target substances maintained in the fluid cell, or interactions between diffusion-mixed reagents in adjacent fluids, may be analyzed by standard analysis methods.

17 citations


Cited by
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Journal ArticleDOI
27 Jul 2006-Nature
TL;DR: The manipulation of fluids in channels with dimensions of tens of micrometres — microfluidics — has emerged as a distinct new field that has the potential to influence subject areas from chemical synthesis and biological analysis to optics and information technology.
Abstract: The manipulation of fluids in channels with dimensions of tens of micrometres--microfluidics--has emerged as a distinct new field. Microfluidics has the potential to influence subject areas from chemical synthesis and biological analysis to optics and information technology. But the field is still at an early stage of development. Even as the basic science and technological demonstrations develop, other problems must be addressed: choosing and focusing on initial applications, and developing strategies to complete the cycle of development, including commercialization. The solutions to these problems will require imagination and ingenuity.

8,260 citations

Journal ArticleDOI
TL;DR: It is reported that magnetite nanoparticles in fact possess an intrinsic enzyme mimetic activity similar to that found in natural peroxidases, which are widely used to oxidize organic substrates in the treatment of wastewater or as detection tools.
Abstract: Nanoparticles containing magnetic materials, such as magnetite (Fe3O4), are particularly useful for imaging and separation techniques. As these nanoparticles are generally considered to be biologically and chemically inert, they are typically coated with metal catalysts, antibodies or enzymes to increase their functionality as separation agents. Here, we report that magnetite nanoparticles in fact possess an intrinsic enzyme mimetic activity similar to that found in natural peroxidases, which are widely used to oxidize organic substrates in the treatment of wastewater or as detection tools. Based on this finding, we have developed a novel immunoassay in which antibody-modified magnetite nanoparticles provide three functions: capture, separation and detection. The stability, ease of production and versatility of these nanoparticles makes them a powerful tool for a wide range of potential applications in medicine, biotechnology and environmental chemistry.

4,500 citations

Journal ArticleDOI
TL;DR: The ability of DLLME technique in the extraction of other organic compounds such as organochlorine pesticides, organophosphorus pesticides and substituted benzene compounds were studied.

2,959 citations

Journal ArticleDOI
TL;DR: It is concluded that when nonmonotonic dose-response curves occur, the effects of low doses cannot be predicted by the effects observed at high doses, and fundamental changes in chemical testing and safety determination are needed to protect human health.
Abstract: For decades, studies of endocrine-disrupting chemicals (EDCs) have challenged traditional concepts in toxicology, in particular the dogma of “the dose makes the poison,” because EDCs can have effects at low doses that are not predicted by effects at higher doses. Here, we review two major concepts in EDC studies: low dose and nonmonotonicity. Low-dose effects were defined by the National Toxicology Program as those that occur in the range of human exposures or effects observed at doses below those used for traditional toxicological studies. We review the mechanistic data for low-dose effects and use a weight-of-evidence approach to analyze five examples from the EDC literature. Additionally, we explore nonmonotonic dose-response curves, defined as a nonlinear relationship between dose and effect where the slope of the curve changes sign somewhere within the range of doses examined. We provide a detailed discussion of the mechanisms responsible for generating these phenomena, plus hundreds of examples from...

2,475 citations

Journal ArticleDOI
23 Sep 2011-Thyroid
TL;DR: The revised guidelines for the management of thyroid disease in pregnancy include recommendations regarding the interpretation of thyroid function tests in pregnancy, iodine nutrition, thyroid autoantibodies and pregnancy complications, thyroid considerations in infertile women, hypothyroidism in pregnancy and thyrotoxicosis in pregnancy.
Abstract: Background: Thyroid disease in pregnancy is a common clinical problem. Since the guidelines for the management of these disorders by the American Thyroid Association (ATA) were first published in 2...

2,409 citations