Uma T. Kumar

University of Cincinnati, Cincinnati, OH, United States

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Publications (4)10.81 Total impact

  • U T Kumar, N P Vela, J A Caruso
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    ABSTRACT: Organometal compounds of arsenic, antimony, and mercury are speciated using supercritical fluid chromatography with inductively coupled plasma mass spectrometric (ICP-MS) detection. The multi-element capability of ICP-MS for transient signals is examined by detecting five compounds containing all three elements in a single chromatographic injection. The results obtained are compared with those obtained from flame-ionization detection (FID). Trimethyl arsine is not distinguished from the solvent peak when FID is used because it coelutes with the solvent, whereas trimethyl arsine is detected when ICP-MS is used because of its element-selective nature. The detection limits obtained by ICP-MS are 2-3 orders of magnitude lower than those obtained by FID. Determination of isotope abundance is also demonstrated for triphenyl antimony and diphenyl mercury compounds.
    Journal of chromatographic science 12/1995; 33(11):606-10. · 0.79 Impact Factor
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    ABSTRACT: Inductively coupled plasma-mass spectrometry is investigated for the detection of metalloporphyrins (cobalt protoporphyrin, hemin, and zinc protoporphyrin) separated by liquid chromatography. A Hypersil SAS C1 column with mobile phase containing 68% methanol at a pH of 4.5 is used. The detection limits obtained are in the nanogram range for cobalt and zinc protoporphyrins, whereas for hemin, detection limits are in the microgram range. The accuracy of the method is evaluated by determining zinc protoporphyrin from the whole blood of a lead-poisoned patient.
    Journal of chromatographic science 08/1994; 32(7):282-5. · 0.79 Impact Factor
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    ABSTRACT: Supercritical fluid extraction is used to extract tributyltin and triphenyltin from biological samples. The extraction conditions with carbon dioxide as supercritical fluid (methanol modifier used) are optimized for the organotins from fish tissue certified reference material. The total extraction time is found to be approximately 15 min. The recovery studies at the optimal conditions shows a recovery of 44% for tributyltin and 23% for triphenyltin. The reproducibilities for both the compounds extracted are within 2% R.S.D. The optimum conditions obtained are also used to extract tributyltin and triphenyltin from tuna fish obtained from a local grocery store.
    Journal of Chromatography A 01/1994; · 4.61 Impact Factor
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    ABSTRACT: This paper described the effect of inorganic tin chloride on the separation of trimethyl-, tributyl- and triphenyltinchlorides by reversed-phase ion-pair high-performance liquid chromatography with detection by inductively coupled plasma mass spectrometry. The detection limits are 1.6 pg, 1.5 pg and 2.3 pg as tin for trimethyltin, tributyltin and triphenyltin, respectively. The relative standard deviation for ten injections of 20 ng of the tin compounds was less than 5%. Inorganic tin was held strongly on the columns used, to a greater extent on the silica column compared to the polymer column. Extraction and determination of tributyltin and triphenyltin as chlorides in fish tissue (certified reference material) and tuna fish (grocery store) were performed. The recovery study from fish tissue showed an efficiency of over 90% for bothy tributyltin and triphenyltin and over 60% recovery for spiked tuna.
    Journal of Chromatography A 12/1993; · 4.61 Impact Factor