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 paper, a nonlinear absorbance amplifier for coherent etalon was proposed, where the dielectric spacer is a weakly absorbing solution, and the observed net absorbance is equal to -log (10/sup -3A/4/(1 -R/sub w/)/(1 - 10/sup −A/2/R/Sub w/)) where R/sub is the reflectance of the windows and A is the absorbance of a solution in a conventional cell.
Abstract: An etalon, where the dielectric spacer is a weakly absorbing solution, forms a nonlinear absorbance amplifier. The observed net absorbance is equal to -log (10/sup -3A/4/(1 -R/sub w/)/(1 - 10/sup -A/2/R/sub w/)) where R/sub w/ is the reflectance of the windows and A is the absorbance of the same solution in a conventional cell. Reasonable agreement between theory and experiment is observed for a coherent source. For conventional sources, the observed amplification factor is much higher due to beam divergence, multipath effect, and multiple beam interference.
21 citations
TL;DR: The ability of sulfonated styrene-divinylbenzene based stationary phases to separate the hydrogen ion from other monovalent cations is demonstrated, allowing the rapid quantitation of strong acids and weak acids.
Abstract: The practice of determining acid concentrations by titrations has remained unchanged for more than a century. We introduce a new approach to the determination of acid concentrations based on cation exchange chromatography. We demonstrate the ability of sulfonated styrene-divinylbenzene based stationary phases to separate the hydrogen ion from other monovalent cations. The eluent is a dilute solution of a neutral salt, sometimes containing a small concentration of the corresponding acid, e.g., sodium ethanesulfonate, pH adjusted with ethanesulfonic acid. The high equivalent conductance (approximately 350 S.cm2/equiv) of H+ and relatively low eluent concentration allows sensitive conductometric detection of H+, down to the 50 microM level under favorable conditions. The conductometric response to H+ can be linear over a wide range of H+ concentrations, from sub-millimolar to several molar concentrations. The system allows the rapid quantitation of strong acids; weak acids can also be determined depending on pKa and injected concentration. The determinations of several strong and weak acids are presented along with factors that govern their chromatographic analysis.
21 citations
TL;DR: In this paper, a dual membrane annular helical configuration was shown to be a highly efficient low dispersion suppressor for ion chromatography, which contained one filament-filled membrane tube inserted inside another closely fitting membrane tube of the same type.
Abstract: A dual membrane annular helical configuration is shown to be a highly efficient low dispersion suppressor for ion chromatography. The device contains one filament-filled membrane tube inserted inside another closely fitting membrane tube of the same type. The dual membrane assembly is coiled as a small diameter helix, the shape being retained by the filament. The column effluent flows in the annular space between the two membranes; regenerant flows through two separate channels, inside the inner membrane and through a jacket which surrounds the entire device. Compared to simple filament-filled membrane helices, these devices exhibit a substantially larger available membrane surface area per unit dispersion of an injected band. 20 references, 3 tables, 2 figures.
21 citations
TL;DR: In this paper, three semi-continuous methods for detecting nitric acid (HNO3) were tested against the annular denuder + filter pack (ADS) integrated collection technique at the Tampa Bay Regional Atmospheric Chemistry Experiment (BRACE) Sydney research station ∼ 20 km downwind of the Tampa, Florida, urban core.
21 citations
TL;DR: The utility of a liquid core waveguide (LCW) system for acting as a sentry monitor for compounds such as benzene, toluene, ethylbenzene, xylene (BTEX) in water was examined in this article.
21 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