Wyniki wyszukiwania dla: Purnendu K. Dasgupta

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Functionalization of High‐Density Polyethylene Capillaries for Open Tubular Ion Chromatography

Enas Yousef, Charles Phillip Shelor, Seth A. Horn, Purnendu K. Dasgupta

Journal of Separation Science > 47 > 19 > n/a - n/a

Ion chromatography is the anion analysis benchmark. A miniature form, Open Tubular Ion Chromatography (OTIC), has attractive attributes for efficient ion separations. Here, we fabricate and characterize high‐density polyethylene (HDPE) open tubular anion exchange columns (OTCs). We attach positively charged latex particles onto negatively charged capillary surfaces. For efficient OTIC, column diameters...

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In honour of the 80th birthday of Professor Gary Christian

Purnendu K Dasgupta

Talanta > 2018 > 177 > C > 1-3

artykuł

Continuous measurement of elemental composition of ambient aerosol by induction-coupled plasma mass spectrometry

Santosh K. Mishra, Bhargab Chattopadhyay, Akinde F. Kadjo, Purnendu K. Dasgupta

Talanta > 2018 > 177 > C > 197-202

There is presently no instrumentation that can provide (near) real time information on elemental composition of atmospheric aerosols. We describe an arrangement where air is sampled through a cyclone @30L/min with a 50% cutoff @ ~250nm. The particles deposit into a cup through which deionized water is continuously flowing. High purity HNO₃ is added downstream and the mixed stream optionally flows...

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Automated programmable pressurized carbonic acid eluent ion exclusion chromatography of organic acids

C. Phillip Shelor, Purnendu K. Dasgupta

Journal of Chromatography A > 2017 > 1523 > C > 300-308

Conductometric ion exclusion chromatography of weak acids does not enjoy the same degree of success as its counterpart in suppressed conductometric anion exchange chromatography. Compared to the latter, eluent preparation is not automated. Commonly, a strong acid is used as the eluent leading to a relatively high-detector background and poorer limits of detection. In addition, generally applicable...

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Matrix isolation with an ion transfer device for interference-free simultaneous spectrophotometric determinations of hexavalent and trivalent chromium in a flow-based system

Shin-Ichi Ohira, Koretaka Nakamura, Mitsuki Chiba, Purnendu K. Dasgupta, więcej

Talanta > 2017 > 164 > C > 445-450

Chromium speciation by spectrophotometric determination of hexavalent chromium (Cr(VI)) with diphenylcarbazide (DPC) has several problems. These include: (1) the inability to directly detect trivalent chromium (Cr(III)) with DPC, (2) positive interference in Cr(VI) determination by other metal cations and (3) negative interference by any reducing agent present in the sample. These are addressed with...

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Sampling frequency, response times and embedded signal filtration in fast, high efficiency liquid chromatography: A tutorial

M. Farooq Wahab, Purnendu K. Dasgupta, Akinde F. Kadjo, Daniel W. Armstrong

Analytica Chimica Acta > 2016 > 907 > C > 31-44

With increasingly efficient columns, eluite peaks are increasingly narrower. To take full advantage of this, choice of the detector response time and the data acquisition rate a.k.a. detector sampling frequency, have become increasingly important. In this work, we revisit the concept of data sampling from the theorem variously attributed to Whittaker, Nyquist, Kotelnikov, and Shannon. Focusing on...

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Electrodialytic matrix isolation for metal cations

Shin-Ichi Ohira, Yuri Hiroyama, Koretaka Nakamura, Takumi Koda, więcej

Talanta > 2015 > 132 > Complete > 228-233

Electrodialytic ion transfer was studied as a matrix isolation tool for heavy metal determinations. An ion transfer device (ITD) was used for the transfer of heavy metal cations. Under optimized flow rates applied voltage and receptor composition, heavy metal ions were quantitatively transferred at concentrations spanning µgL ⁻¹ to mgL ⁻¹ . As long as the sample pH was acidic, there...

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On-line electrodialytic matrix isolation for chromatographic determination of organic acids in wine

Shin-Ichi Ohira, Kenta Kuhara, Aki Shigetomi, Takayuki Yamasaki, więcej

Journal of Chromatography A > 2014 > 1372 > Complete > 18-24

Chromatographic determination of organic acids is widely performed, but the matrix often calls for lengthy and elaborate sample preparation prior to actual analysis. Matrix components, e.g., proteins, non-ionics, lipids etc. are typically removed by a combination of centrifugation/filtration and solid phase extraction (SPE) that may include the use of ion-exchange media. Here we report the quantitative...

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Expanding the linear dynamic range for quantitative liquid chromatography-high resolution mass spectrometry utilizing natural isotopologue signals

Hanghui Liu, Lily Lam, Lin Yan, Bert Chi, więcej

Analytica Chimica Acta > 2014 > 850 > Complete > 65-70

The linear dynamic range (LDR) for quantitative liquid chromatography–mass spectrometry can be extended until ionization saturation is reached by using a number of target isotopologue ions in addition to the normally used target ion that provides the highest sensitivity. Less abundant isotopologue ions extend the LDR: the lower ion abundance decreases the probability of ion detector saturation. Effectively...

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Speciation and detection of arsenic in aqueous samples: A review of recent progress in non-atomic spectrometric methods

Jian Ma, Mrinal K. Sengupta, Dongxing Yuan, Purnendu K. Dasgupta

Analytica Chimica Acta > 2014 > 831 > Complete > 1-23

Inorganic arsenic (As) displays extreme toxicity and is a class A human carcinogen. It is of interest to both analytical chemists and environmental scientists. Facile and sensitive determination of As and knowledge of the speciation of forms of As in aqueous samples are vitally important. Nearly every nation has relevant official regulations on permissible limits of drinking water As content. The...

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Tutorial: Simulating chromatography with Microsoft Excel Macros

Akinde Kadjo, Purnendu K. Dasgupta

Analytica Chimica Acta > 2013 > 773 > Complete > 1-8

Chromatography is one of the cornerstones of modern analytical chemistry; developing an instinctive feeling for how chromatography works will be invaluable to future generation of chromatographers. Specialized software programs exist that handle and manipulate chromatographic data; there are also some that simulate chromatograms. However, the algorithm details of such software are not transparent...

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A disposable blood cyanide sensor

Yong Tian, Purnendu K. Dasgupta, Sari B. Mahon, Jian Ma, więcej

Analytica Chimica Acta > 2013 > 768 > Complete > 129-135

Deaths due to smoke inhalation in fires are often due to poisoning by HCN. Rapid administration of antidotes can result in complete resuscitation of the patient but judicious dosing requires the knowledge of the level of cyanide exposure. Rapid sensitive means for blood cyanide quantitation are needed. Hydroxocyanocobinamide (OH(CN)Cbi) reacts with cyanide rapidly; this is accompanied by a large spectral...

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Relative source contributions for perchlorate exposures in a lactating human cohort

Andrea B. Kirk, Jason V. Dyke, Shin-Ichi Ohira, Purnendu K. Dasgupta

Science of the Total Environment > 2013 > 443 > Complete > 939-943

Perchlorate is an iodine-uptake inhibitor and common contaminant of food and drinking water. Understanding the amount of perchlorate exposure occurring through non-water sources is essential for accurate estimates of human exposure levels, and establishment of drinking water limits for this pervasive contaminant. The study objective was to determine the amount of perchlorate intake derived from diet...

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Co-deposition and distribution of arsenic and oxidizable organic carbon in the sedimentary basin of West Bengal, India

Sayan Bhattacharya, Gunjan Guha, Dhrubajyoti Chattopadhyay, Aniruddha Mukhopadhyay, więcej

Journal of Analytical Science and Technology > 2013 > 4 > 1 > 1-5

Background The study investigated the extent of soil arsenic (As) contamination in agricultural plots in Bengal Delta through contaminated groundwater irrigation. Edaphic levels of As and oxidizable organic carbon (OOC) were tested along a depth gradient (0 to 160 ft) in agricultural plots. Methods Soil samples were collected from surface up to 160 feet depth at every 5 feet. By boreholes drilling...

artykuł

Characterization of a constant current charge detector

Masanobu Mori, Yongjing Chen, Shin-Ichi Ohira, Purnendu K. Dasgupta

Talanta > 2012 > 102 > Complete > 44-52

Ion exchangers are ionic equivalents of doped semiconductors, where cations and anions are equivalents of holes and electrons as charge carriers in solid state semiconductors. We have previously demonstrated an ion exchange membrane (IEM) based electrolyte generator which behaves similar to a light-emitting diode and a charge detector (ChD) which behaves analogous to a p–i–n photodiode. The previous...

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Automated on-line preconcentration of trace aqueous mercury with gold trap focusing for cold vapor atomic absorption spectrometry

Mahitti Puanngam, Purnendu K. Dasgupta, Fuangfa Unob

Talanta > 2012 > 99 > Complete > 1040-1045

A fully automated system for the determination of trace mercury in water by cold vapor atomic absorption spectrometry (CVAAS) is reported. The system uses preconcentration on a novel sorbent followed by liberation of the mercury and focusing by a gold trap. Mercury ions were extracted from water samples by passage through a solid phase sorbent column containing 2-(3-(2-aminoethylthio)propylthio)ethanamine...

artykuł

Cobinamide chemistries for photometric cyanide determination. A merging zone liquid core waveguide cyanide analyzer using cyanoaquacobinamide

Jian Ma, Purnendu K. Dasgupta, Felix H. Zelder, Gerry R. Boss

Analytica Chimica Acta > 2012 > 736 > Complete > 78-84

Diaquacobinamide (H ₂ O) ₂ Cbi ²⁺ or its conjugate base hydroxyaquacobinamide (OH(H ₂ O)Cbi ⁺ )) can bind up to two cyanide ions, making dicyanocobinamide. This transition is accompanied by a significant change in color, previously exploited for cyanide determination. The reagent OH(H ₂ O)Cbi ⁺ is used in excess; when trace amounts of cyanide...

artykuł

Resolving DNA in free solution

Xiayan Wang, Lei Liu, Guangsheng Guo, Wei Wang, więcej

Trends in Analytical Chemistry > 2012 > 35 > Complete > 122-134

DNA molecules are usually separated by gel electrophoresis. While gels help resolve DNA, the polymers bring problems to the analysis (e.g., difficulty in automating and poor reproducibility). One way to eliminate these problems completely is to separate DNA in free solutions. However, DNA fragments cannot normally be resolved in a free solution by electrophoresis because the electrophoretic mobilities...

artykuł

Perchlorate, iodine supplements, iodized salt and breast milk iodine content

Andrea B. Kirk, Martina Kroll, Jason V. Dyke, Shin-Ichi Ohira, więcej

Science of the Total Environment > 2012 > 420 > Complete > 73-78

This study was undertaken to determine if increasing maternal iodine intake through single dose tablets will decrease breast milk concentrations of the iodine-uptake inhibitor, perchlorate, through competitive inhibition. We also sought to determine if the timing of supplementation influences the fraction of iodine excreted in milk versus urine and to compare the effectiveness of iodized salt as a...

artykuł

Oxidation State-Differentiated Measurement of Aqueous Inorganic Arsenic by Continuous Flow Electrochemical Arsine Generation Coupled to Gas-Phase Chemiluminescence Detection

Mrinal K. Sengupta, Purnendu K. Dasgupta

Analytical Chemistry > 2011 > 83 > 24 > 9378 - 9383

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