Author
Purnendu K. Dasgupta
Other affiliations: Dow Chemical Company, Texas Tech University, University of California, Davis ...read more
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 published on a yearly basis
Papers
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TL;DR: In this article, perchlorate, thiocyanate, and iodine excretion in urine and milk of 13 breastfeeding women was investigated and the results were interpreted by a model of parallel/competitive transport of these species by the sodium iodide symporter.
Abstract: Perchlorate, thiocyanate, and iodine excretion in urine and milk of 13 breastfeeding women was investigated and the results were interpreted by a model of parallel/competitive transport of these species by the sodium iodide symporter. For each species i, we assumed physiological homeostasis, where iT,in equals the corresponding total excretion in urine and milk (ie,u + ie,m). The fraction of the total excretion that appeared in milk fi,m was measured and ranged from 0.394−0.781, 0.018−0.144, and 0.086−0.464 for perchlorate, thiocyanate, and iodine, respectively. The corresponding median values were 0.541, 0.053, and 0.177, respectively. The selectivity factors of perchlorate over iodide transport, and thiocyanate over iodide transport, defined as fPC,m/fI,m, and fSCN,m/fI,m, respectively, were 3.14 ± 1.20 and 0.27 ± 0.26 while PCT,in, SCNT,in, and IT,in among individuals varied 4.9, 5.0, and 8.4×, respectively. These transport selectivities are an order of magnitude lower than those indicated by in vitro ...
69 citations
TL;DR: In this article, a dual membrane helical electrodialytic suppressor is described, where a platinum-wire-filled tube made of Naflon perfluorosulfonate membrane is coiled into a helix and a dc voltage is applied across the carbon bed and the platinum wire.
Abstract: A dual membrane helical electrodialytic suppressor is described. A platinum-wire-filled tube made of Naflon perfluorosulfonate membrane, inserted in another perfluorosulfonate membrane tube, is coiled into a helix. The helical assembly is inserted within an outer jacked packed with granular conductive carbon. An alkaline eluent, e.g., NaOH or Na/sub 2/CO/sub 3/, flows in the annular channel between the two membranes and pure water flows through the inner membrane and the outer jacket, countercurrent to the eluent flow. A dc voltage (typically 3-8 V) is applied across the carbon bed and the platinum wire. Na/sup +/ in the eluent migrates to the cathode compartment resulting in water as the suppressed effluent and NaOH as the catholyte effluent. The dual membrane design prevents direct electrode contact with the eluent; bubble induced noise in the suppressed eluent due to any residual gas is eliminated or minimized with a microporous gas-permeable membrane tube or by applying sufficient back pressure to the detectors exit. Up to 500 /mu/equiv of NaOH/min can be quantitatively suppressed with a membrane length of 50 cm and a band dispersion of 106 /mu/L (20-/mu/L sample). With typical eluents, the system permits detection limits in the low-parts-per-billion level for most common anions.
69 citations
67 citations
TL;DR: In this paper, the authors present design and construction details of both a ground-based instrument and an instrument intended for aircraft use and provide illustrative field data for both, and outline their rationale to return to PD-based chemistry, and show that nearly equivalent LODs can be obtained with reagent components that are separated rather than a single mixed reagent in combination with a fluorescence detector that utilizes multiple high intensity light emitting diodes (LEDs) for excitation without the benefit of a Teflon AF based waveguide, the use of which has become more
67 citations
TL;DR: The extensive data set represented in this paper underscores that urban HCHO measurements can now be made easily; the agreement between disparate instruments further indicates that such measurements can be done reliably and accurately for this very important atmospheric species.
Abstract: First, we briefly review the atmospheric chemistry and previous intercomparison measurements for HCHO, with special reference to the diffusion scrubber Hantzsch reaction based fluorescence instrument used in the field studies reported herein. Then we discuss summertime HCHO levels in five major U.S. cities measured over 1999−2002, primarily from ground-based measurements. Land−sea breeze circulations play a major role in observed concentrations in coastal cities. Very high HCHO peak mixing ratios were observed in Houston (>47 ppb) where the overall median mixing ratio was 3.3 ppb; the corre sponding values in Atlanta were ∼>18 and 7.9 ppb, respectively. The peak and median mixing ratios (9.3 and 2.3 ppb) were the lowest for Tampa, where the land−sea breeze also played an important role. In several cities, replicate HCHO measurements were made by direct spectroscopic instruments; the instruments were located kilometers from each other and addressed very different heights (e.g., 106 vs 10 m). Even under the...
66 citations
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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
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
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
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
Brigham and Women's Hospital1, Boston University2, University of California, Los Angeles3, Boston Children's Hospital4, University of Alabama at Birmingham5, Stanford University6, Northwestern University7, Aalborg University8, Cardiff University9, University of Pennsylvania10, Erasmus University Rotterdam11, Medical University of South Carolina12
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