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.

New applications of chemiluminescence for selective gas analysis

Abstract: Chemiluminescence (CL) is a powerful analytical tool for trace gas measurements. In this mini-review, we present reactions and spectra of ozone-induced CL for various compounds and techniques for detecting such CL. Next discussed are CL applications where real gas samples were successfully measured. Chemiluminescence monitoring has been used as universal nitrogen and sulfur detectors for gas chromatography and capillary electrophoresis. Chemiluminescence detection can be used as the basis of compact, affordable, and sensitive analyzers for real-sample analysis. Isoprene and sulfur compounds in breath and atmospheric samples have been successfully measured by coupling with a small collection system. Short-term (5 min) sorbent collection enhances the CL signal and considerably reduces interference. For sulfur gas analysis, methyl mercaptan and dimethyl sulfide can be separated on the same column that is used for collection. Waterborne arsenic is measured by automated arsine generation and CL reaction of ars...

Flow batteries for microfluidic networks: configuring an electroosmotic pump for nonterminal positions.

Abstract: A micropump provides flow and pressure for a lab-on-chip device, just as a battery supplies current and voltage for an electronic system. Numerous micropumps have been developed, but none is as versatile as a battery. One cannot easily insert a micropump into a nonterminal position of a fluidic line without affecting the rest of the fluidic system, and one cannot simply connect several micropumps in series to enhance the pressure output, etc. In this work we develop a flow battery (or pressure power supply) to address this issue. A flow battery consists of a +EOP (in which the liquid flows in the same direction as the field gradient) and a −EOP (in which the liquid flows opposite to the electric field gradient), and the outlet of the +EOP is directly connected to the inlet of the −EOP. An external high voltage is applied to this outlet−inlet joint via a short gel-filled capillary that allows ions but not bulk liquid flow, while the +EOP’s inlet and the −EOP’s outlet (the flow battery’s inlet and outlet) a...

Ion detector and system

Abstract: Apparatus and method for detecting current or potential generated in a liquid sample suitable for use in a chromatography or other liquid sample analytical system. One embodiment is an electrolytic ion transfer device with a signal detector in communication with the electrodes of the transfer device. Another is a combination ion transfer device/electrolyte generator. Another substitutes a detector for the ion transfer device in the combination.

Automated measurement of lipid hydroperoxides in oil and fat samples by flow injection photometry

Abstract: The status of oxidation of oil and fat samples is normally judged by their peroxide value (PV), an index that seeks to determine the peroxide content by measuring how much iodine is liberated by the sample from iodide in an acidic medium in a specified time period. At peroxide levels of interest, not only does this approach require considerable analyst skill, the method is inherently flawed because of the considerable differences in the rates at which different peroxides liberate iodine from iodide and potentially also the consumption of nascent iodine by unsaturated sites. We propose here a substantially less biased method based on the oxidation of Fe(II) to Fe(III) by peroxides, followed by the colorimetric detection of the latter as the thiocyanate complex. The system is automated through flow injection photometry. A methanol−butanol mixed solvent is used as the carrier stream. Samples, generally prediluted in the same solvent, are injected into this carrier; streams bearing Fe2+ and SCN- are separatel...

The origins and the future of microfluidics

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.

Intrinsic peroxidase-like activity of ferromagnetic nanoparticles

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.

Hormones and endocrine-disrupting chemicals: Low-dose effects and nonmonotonic dose responses

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...

2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum

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...