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Sample records for systems spectrometric potentiometric

  1. A Printed Organic Amplification System for Wearable Potentiometric Electrochemical Sensors.

    Science.gov (United States)

    Shiwaku, Rei; Matsui, Hiroyuki; Nagamine, Kuniaki; Uematsu, Mayu; Mano, Taisei; Maruyama, Yuki; Nomura, Ayako; Tsuchiya, Kazuhiko; Hayasaka, Kazuma; Takeda, Yasunori; Fukuda, Takashi; Kumaki, Daisuke; Tokito, Shizuo

    2018-03-02

    Electrochemical sensor systems with integrated amplifier circuits play an important role in measuring physiological signals via in situ human perspiration analysis. Signal processing circuitry based on organic thin-film transistors (OTFTs) have significant potential in realizing wearable sensor devices due to their superior mechanical flexibility and biocompatibility. Here, we demonstrate a novel potentiometric electrochemical sensing system comprised of a potassium ion (K + ) sensor and amplifier circuits employing OTFT-based pseudo-CMOS inverters, which have a highly controllable switching voltage and closed-loop gain. The ion concentration sensitivity of the fabricated K + sensor was 34 mV/dec, which was amplified to 160 mV/dec (by a factor of 4.6) with high linearity. The developed system is expected to help further the realization of ultra-thin and flexible wearable sensor devices for healthcare applications.

  2. System for Gamma an X rays fluorescence spectrometric

    International Nuclear Information System (INIS)

    Alonso Abad, D.; Arista Romeu, E.; Bolanos Perez, L. and others

    1997-01-01

    A system for spectrometry of gamma or fluorescence X rays is presented. It sis composed by a Si(Li) semiconductors detector, a charge sensitive preamplifier, a high voltage power supply, a spectrometric amplifier and a monolithic 1024 channels multichannel analyzers or an IBM compatible 4096 channels add - on- card multichannel analyzer. The system can be configured as a 1024 or 4096 channels gamma or fluorescent X rays spectrometer

  3. Gamma spectrometric system based on the personal computer Pravetz-83

    International Nuclear Information System (INIS)

    Yanakiev, K; Grigorov, T.; Vuchkov, M.

    1985-01-01

    A gamma spectrometric system based on a personal microcomputer Pravets-85 is described. The analog modules are NIM standard. ADC data are stored in the memory of the computer via a DMA channel and a real-time data processing is possible. The results from a series of tests indicate that the performance of the system is comparable with that of comercially avalable computerized spectrometers Ortec and Canberra

  4. Actively shielded low level gamma - spectrometric system

    International Nuclear Information System (INIS)

    Mrdja, D.; Bikit, I.; Forkapic, S.; Slivka, J.; Veskovic, M.

    2005-01-01

    The results of the adjusting and testing of the actively shielded low level gamma-spectrometry system are presented. The veto action of the shield reduces the background in the energy region of 50 keV to the 2800 keV for about 3 times. (author) [sr

  5. Potentiometric surfaces of the intermediate aquifer system, west-central Florida, May, 1993

    Science.gov (United States)

    Mularoni, R.A.

    1994-01-01

    The intermediate aquifer system underlies a 5000-sq-mi area including De Soto, Sarasota, Hardee, Manatee, and parts of Charlotte, Hillsborough, Highlands, and Polk Counties, Florida. It is overlain by the surf@cial aquifer system and underlain by the Floridan aquifer system. The potentiometric surface of the intermediate aquifer system was mapped by determining the altitude of water levels in a network of wells and represented on a map by contours that connect points of equal altitude. This map represents water-level conditions near the end of the spring dry season when ground- water withdrawals for agricultural use were high. The cumulative rainfall for the study area was 4.84 inches above normal for the period from June 1992 to May 1993. Hydrographs for selected wells indicated that the annual and seasonal fluctuations of the water levels were generally large (greater than 15 feet) in the central interior region where water demand for irrigation is high during the fall and spring. Seasonal fluctuations were smaller in the northern recharge area where water use is predominantly for public supply. Water levels measured in May 1993 for the composite intermediate aquifer potentiometric surface were lower than those measured in May or September 1992. A cone of depression exists in the potentiometric surface for the composite aquifer system at Warm Mineral Springs, which is a natural discharge point from this system.

  6. An estimated potentiometric surface of the Death Valley region, Nevada and California, developed using geographic information system and automated interpolation techniques

    International Nuclear Information System (INIS)

    D'Agnese, F.A.; Faunt, C.C.; Turner, A.K.

    1998-01-01

    An estimated potentiometric surface was constructed for the Death Valley region, Nevada and California, from numerous, disparate data sets. The potentiometric surface was required for conceptualization of the ground-water flow system and for construction of a numerical model to aid in the regional characterization for the Yucca Mountain repository. Because accurate, manual extrapolation of potentiometric levels over large distances is difficult, a geographic-information-system method was developed to incorporate available data and apply hydrogeologic rules during contour construction. Altitudes of lakes, springs, and wetlands, interpreted as areas where the potentiometric surface intercepts the land surface, were combined with water levels from well data. Because interpreted ground-water recharge and discharge areas commonly coincide with groundwater basin boundaries, these areas also were used to constrain a gridding algorithm and to appropriately place local maxima and minima in the potentiometric-surface map. The resulting initial potentiometric surface was examined to define areas where the algorithm incorrectly extrapolated the potentiometric surface above the land surface. A map of low-permeability rocks overlaid on the potentiometric surface also indicated areas that required editing based on hydrogeologic reasoning. An interactive editor was used to adjust generated contours to better represent the natural water table conditions, such as large hydraulic gradients and troughs, or ''vees''. The resulting estimated potentiometric-surface map agreed well with previously constructed maps. Potentiometric-surface characteristics including potentiometric-surface mounds and depressions, surface troughs, and large hydraulic gradients were described

  7. Potentiometric investigations of molecular heteroconjugation equilibria of substituted phenol+n-butylamine systems in dimethyl sulfoxide

    International Nuclear Information System (INIS)

    Czaja, MaIgorzata; Baginska, Katarzyna; Kozak, Anna; Makowski, Mariusz; Chmurzynski, Lech

    2005-01-01

    Molecular heteroconjugation constants, K BHA DMSO and K AHB DMSO , expressed as their logarithms, have been determined by potentiometric titration for eleven substituted phenol+n-butylamine systems in a polar protophilic aprotic solvent, dimethyl sulfoxide (DMSO). An increasing tendency towards molecular heteroconjugation in these systems without proton transfer has been found with increasing pK a DMSO (HA), i.e., with decreasing phenol acidity. Moreover, a linear correlation has been established between the determined lgK BHA DMSO values and pK a DMSO (HA). Furthermore, overall stability constants, lgK o DMSO , could be correlated linearly with pK a DMSO (HA) values

  8. Disposable Miniaturized Screen‐Printed pH and Reference Electrodes for Potentiometric Systems

    DEFF Research Database (Denmark)

    Musa, Arnaud Emmanuel; del Campo, Francisco Javier; Abramova, Natalia

    2011-01-01

    This work describes the development of a miniaturized potentiometric system comprising a miniaturized quasi‐reference electrode (QRE) coupled to a solid‐state ion‐selective electrode (ISE) for the monitoring of pH. We describe the optimization of materials and fabrication processes including screen‐printing...... electrode) that can be used continuously for a period of not less than 7 days in aqueous solutions. Curing the Ag/AgCl pastes during 20 minutes at 120 °C after printing allowed the QREs to display excellent potential stability, as demonstrated by an open‐circuit‐potential standard deviation of ±1.2 mV over...

  9. Use of the potentiometric titration method to investigate heterogeneous systems including phosphorylated complexones

    International Nuclear Information System (INIS)

    Tereshin, G.S.; Kharitonova, L.K.; Kuznetsova, O.B.

    1979-01-01

    Heterogeneous systems Y(NO 3 ) 3 (YCl 3 )-Hsub(n)L-KNO 3 (KCl)-H 2 O are investigated by potentiometric titration (with coulomb-meter generation of oH - ions). Hsub(n)L is one of the following: oxyethylidendiphosphonic; aminobenzilidendiphosphonic; glycine-bis-methyl-phosphonic; nitrilotrimethylphosphonic (H 6 L) and ethylenediaminetetramethylphosphonic acids. The range of the exsistence of YHsub(nL3)LxyH 2 O has been determined. The possibility of using potentiometric titration for investigating heterogeneous systems is demonstrated by the stUdy of the system Y(NO 3 ) 3 -H 6 L-KOH-H 2 o by the method of residual concentration. The two methods have shown that at pH 3 LxyH 2 O; at pH=6, KYH 2 Lxy'H 2 O, and at pH=7, K 2 YHLxy''H 2 O. The complete solubility products of nitrilotrimethylphosphonates are evaluated

  10. Direct correlation between potentiometric and impedance biosensing of antibody-antigen interactions using an integrated system

    Science.gov (United States)

    Tsai, Meng-Yen; Creedon, Niamh; Brightbill, Eleanor; Pavlidis, Spyridon; Brown, Billyde; Gray, Darren W.; Shields, Niall; Sayers, Ríona; Mooney, Mark H.; O'Riordan, Alan; Vogel, Eric M.

    2017-08-01

    A fully integrated system that combines extended gate field-effect transistor (EGFET)-based potentiometric biosensors and electrochemical impedance spectroscopy (EIS)-based biosensors has been demonstrated. This integrated configuration enables the sequential measurement of the same immunological binding event on the same sensing surface and consequently sheds light on the fundamental origins of sensing signals produced by FET and EIS biosensors, as well as the correlation between the two. Detection of both the bovine serum albumin (BSA)/anti-BSA model system in buffer solution and bovine parainfluenza antibodies in complex blood plasma samples was demonstrated using the integrated biosensors. Comparison of the EGFET and EIS sensor responses reveals similar dynamic ranges, while equivalent circuit modeling of the EIS response shows that the commonly reported total impedance change (ΔZtotal) is dominated by the change in charge transfer resistance (Rct) rather than surface capacitance (Csurface). Using electrochemical kinetics and the Butler-Volmer equation, we unveil that the surface potential and charge transfer resistance, measured by potentiometric and impedance biosensors, respectively, are, in fact, intrinsically linked. This observation suggests that there is no significant gain in using the FET/EIS integrated system and leads to the demonstration that low-cost EGFET biosensors are sufficient as a detection tool to resolve the charge information of biomolecules for practical sensing applications.

  11. A system design of gamma-ray spectrometric data processing for gold prospecting

    International Nuclear Information System (INIS)

    Yin Xueqin; Cheng Xuchu; Fang Lianxi; Huang Zuofeng.

    1992-01-01

    Based on different correlation between gamma-ray spectrometric data and gold grade in different types of gold deposits, it is necessary and possible to establish a mathematical model of gamma-ray spectrometric data processing for predicting specific gold deposits. A system design of gamma-ray spectrometric data processing for prospecting gold deposits has been worked out according to the mathematical method and procedure of data processing. The prediction effectiveness of commonly used multiple linear regression analysis is always not ideal but regression accuracy will be evidently increased after pre-processing of the calculated weight, deviation and favorability on gamma-ray spectrometric data. This system can establish more than ten models at the same time which enable users to have more choice. Tree structure and Chinese menu prompting are adopted in this system which can be utilized separately, sub-systems at different levels can be also individually operated. It can be transplanted to data processing of other similar geological deposit models (including non-gamma ray spectrometric data). The system is rapid, accurate, simple, convenient and flexible in use, more practical and easily popularized

  12. Potentiometric investigations of molecular heteroconjugation equilibria of substituted phenol+n-butylamine systems in dimethyl sulfoxide

    Energy Technology Data Exchange (ETDEWEB)

    Czaja, MaIgorzata [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Baginska, Katarzyna [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Kozak, Anna [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Makowski, Mariusz [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Chmurzynski, Lech [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland)]. E-mail: lech@chem.univ.gda.pl

    2005-08-15

    Molecular heteroconjugation constants, K{sub BHA}{sup DMSO} and K{sub AHB}{sup DMSO}, expressed as their logarithms, have been determined by potentiometric titration for eleven substituted phenol+n-butylamine systems in a polar protophilic aprotic solvent, dimethyl sulfoxide (DMSO). An increasing tendency towards molecular heteroconjugation in these systems without proton transfer has been found with increasing pK{sub a}{sup DMSO} (HA), i.e., with decreasing phenol acidity. Moreover, a linear correlation has been established between the determined lgK{sub BHA}{sup DMSO} values and pK{sub a}{sup DMSO} (HA). Furthermore, overall stability constants, lgK{sub o}{sup DMSO}, could be correlated linearly with pK{sub a}{sup DMSO} (HA) values.

  13. Real-Time Telemetry System for Amperometric and Potentiometric Electrochemical Sensors

    Directory of Open Access Journals (Sweden)

    Ching-Hsing Luo

    2011-09-01

    Full Text Available A real-time telemetry system, which consists of readout circuits, an analog-to-digital converter (ADC, a microcontroller unit (MCU, a graphical user interface (GUI, and a radio frequency (RF transceiver, is proposed for amperometric and potentiometric electrochemical sensors. By integrating the proposed system with the electrochemical sensors, analyte detection can be conveniently performed. The data is displayed in real-time on a GUI and optionally uploaded to a database via the Internet, allowing it to be accessed remotely. An MCU was implemented using a field programmable gate array (FPGA to filter noise, transmit data, and provide control over peripheral devices to reduce power consumption, which in sleep mode is 70 mW lower than in operating mode. The readout circuits, which were implemented in the TSMC 0.18-μm CMOS process, include a potentiostat and an instrumentation amplifier (IA. The measurement results show that the proposed potentiostat has a detectable current range of 1 nA to 100 μA, and linearity with an R2 value of 0.99998 in each measured current range. The proposed IA has a common-mode rejection ratio (CMRR greater than 90 dB. The proposed system was integrated with a potentiometric pH sensor and an amperometric nitrite sensor for in vitro experiments. The proposed system has high linearity (an R2 value greater than 0.99 was obtained in each experiment, a small size of 5.6 cm × 8.7 cm, high portability, and high integration.

  14. Permian potentiometric analysis

    International Nuclear Information System (INIS)

    Devary, J.L.

    1983-09-01

    Pacific Northwest Laboratory (PNL) was requested to analyze potentiometric data from the Wolfcamp Formation of the Permian System to evaluate the recommendations by the University of Texas/Bureau of Economic Geology (UT/BEG) that additional geohydrologic boreholes be drilled into the Wolfcamp. The UT/BEG recommended that two stratigraphic and two geohydrologic borings be drilled into the Permian System during FY83 and that several shallow hydrologic tests be made in the Dockum Formation. A geostatistical technique known as kriging was applied to objectively evaluate these geohydrologic borehole recommendations. The Deaf Smith County location appears to be an excellent choice for a borehole. No high quality potentiometric data are available from Deaf Smith County and a borehole location immediately upgradient from the candidate repository site is needed. Adding this borehole location to the potentiometric data base will significantly reduce field data uncertainty near the location being studied. The Swisher County location does not appear to be the best choice. High quality data values H2206 and H2360 are located immediately upgradient from the proposed repository site. The best placement of additional geohydrological boreholes in the Wolfcamp Formation depends strongly upon the proposed repository location. The variability of the potentiometric data causes estimation errors to rapidly increase away from locations of field measurements. Suggested locations for additional boreholes for the Deaf Smith investigations are in northwest Randall or central Potter Counties. Ideal borehole locations for the Swisher county studies appear to be in southeast Randall and Armstrong Counties

  15. Potentiometric studies of acid-base interactions in substituted 4-nitropyridine N-oxide systems

    International Nuclear Information System (INIS)

    Gurzynski, Lukasz; Puszko, Aniela; Ostrzechowska, Agnieszka; Makowski, Mariusz; Chmurzynski, Lech

    2006-01-01

    (Acid+base) equilibrium constants, involving the acidity (pK a AC ) and cationic homoconjugation constants (in the form of lgK BHB + AC ), have been determined by the potentiometric method in 13 systems formed by substituted 4-nitropyridine N-oxides in the polar aprotic solvent, acetone (AC). The derivatives covered a wide range of proton-acceptor properties and inherent diversified tendencies towards formation of hydrogen-bonded homocomplexed cations. In addition, the constant values (expressed as pK a AN andlgK BHB + AN ) for two of the systems studied, N-oxides of 2-methylamino- and 2-ethylamino-4-nitropyridine, were determined in acetonitrile (AN). The acidity constants in the non-aqueous media studied have been found to change in line with their substituent effects and the sequence of acidity changes in water. The values of the cationic homoconjugation constants increased with increasing basicity of the N-oxides and decreased with increasing solvent basicity

  16. Potentiometric studies of acid-base interactions in substituted 4-nitropyridine N-oxide systems

    Energy Technology Data Exchange (ETDEWEB)

    Gurzynski, Lukasz [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Puszko, Aniela [Department of Organic Chemistry, School of Economics, Wroclaw (Poland); Ostrzechowska, Agnieszka [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Makowski, Mariusz [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Chmurzynski, Lech [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland)]. E-mail: lech@chem.univ.gda.pl

    2006-05-15

    (Acid+base) equilibrium constants, involving the acidity (pK{sub a}{sup AC}) and cationic homoconjugation constants (in the form of lgK{sub BHB{sup +}}{sup AC}), have been determined by the potentiometric method in 13 systems formed by substituted 4-nitropyridine N-oxides in the polar aprotic solvent, acetone (AC). The derivatives covered a wide range of proton-acceptor properties and inherent diversified tendencies towards formation of hydrogen-bonded homocomplexed cations. In addition, the constant values (expressed as pK{sub a}{sup AN}andlgK{sub BHB{sup +}}{sup AN}) for two of the systems studied, N-oxides of 2-methylamino- and 2-ethylamino-4-nitropyridine, were determined in acetonitrile (AN). The acidity constants in the non-aqueous media studied have been found to change in line with their substituent effects and the sequence of acidity changes in water. The values of the cationic homoconjugation constants increased with increasing basicity of the N-oxides and decreased with increasing solvent basicity.

  17. Potentiometric determination of chloride ions in circulating water systems of the Kirishinefteorgsintez production association

    International Nuclear Information System (INIS)

    Sukhova, N.S.; Skatina, L.I.

    1993-01-01

    The chloride content of circulating water and wastewater in industrial plants is one of the important indexes of contamination. The increasingly stringent sanitary and ecological requirements that have been imposed on wastewater are making it necessary to monitor the chloride content on a regular basis. It is difficult to use the mercurometric method of chloride determination that has been recommended for use in petroleum refineries in analyzing turbid of dark-colored waters with high contents of organic matter. Also, when the mercurometric method is used, accurate control of pH must be maintained in order to achieve good reproducibility of results. The authors are proposing a rapid method for monitoring the content of chloride ions in circulating water systems by potentiometric titration of a sample in a medium of glacial acetic acid by a 0.01 M solution of silver nitrate with the silver indicator electrode and a silver chloride auxiliary electrode EVL-1MZ, filled with a saturated solution of potassium nitrate. The potential is measured 30 sec after it has been established, in a type pH-121 potentiometer. The titration is performed from a microburette with a scale division of 0.02 cm 3 , with constant stirring of the test solution by means of a magnetic stirrer

  18. Maintenance of stability in γ spectrometric system of low active and environmental samples - a practical experience

    International Nuclear Information System (INIS)

    Ravishankar, R.; Bandyopadhyay, T.; Sarkar, P.K.

    2011-01-01

    Particle Accelerators are becoming part of the society with more and more medical and Industrial types are added every year in addition to research type of accelerators. The outflow of materials to the public domain from such accelerator facilities need to checked carefully and must be released after ensuring the activities of such materials should not exceed the regulatory limits. Health Physics Unit, VECC is involved in analyzing food product samples, seized samples which are suspected to contain Uranium etc and other environmental samples in addition to analyzing radioactive materials evolved from Operational Health Physics work. Most of these analyses involve γ Spectrometric Systems of high efficiency and high resolution types. The efficacy of the analysis and results depends on various parameters of the spectrometric system. The electrical noise from the power supply system and other noises picked up, even in the range of a few milli volts range, have been found to affect the stability of the system. These effects may not be present initially during installation but may creep in due course due to various reasons including weather conditions, wear and tear etc. Unless these problems are attended in regular intervals, the stability of the spectrometric systems and hence the results of analysis of the low active and environmental samples, will not be satisfactory. The work describes the practical problems faced by Health Physics Unit, the methods employed in identifying the problems, the necessary remedial measures taken, the final outcome in the stability and the procedures framed in order to avoid in future. (author)

  19. Copper(II) ions interactions in the systems with triamines and ATP. Potentiometric and spectroscopic studies.

    Science.gov (United States)

    Hoffmann, S K; Goslar, J; Bregier-Jarzebowska, R; Gasowska, A; Zalewska, A; Lomozik, L

    2017-12-01

    The mode of interaction and thermodynamic stability of complexes formed in binary and ternary Cu(II)/ATP/triamines systems were studied using potentiometric and spectroscopic (NMR, EPR, UV-Vis) methods. It was found that in binary metal-free systems ATP/H x PA species are formed (PA: Spd=spermidine or 3,3-tri=1,7-diamino-4-azaheptane) where the phosphate groups from nucleotides are preferred negative centers and protonated amine groups of amines are positive centers of reaction. In the ternary systems Cu/ATP/H x (PA) as well as Cu/(ATP)(PA) species are formed. The type of the formed Cu(II) complexes depends on pH of the solution. For a low pH value the complexation appears between Cu(II) and ATP molecules via oxygen atoms of phosphate groups. For a very high pH value, where ATP is hydrolyzed, the Cu(II) ions are bound to the nitrogen atoms of polyamine molecules. We did not detect any direct coordination of the N7 nitrogen atom of adenosine to Cu(II) ions. It means that the CuN7 interaction is an indirect type and can be due to noncovalent interplay including water molecule. EPR studies were performed at glassy state (77K) after a fast freezing both for binary and ternary systems. The glassy state EPR spectra do not reflect species identified in titration studies indicating significant effect of rapid temperature decrease on equilibrium of Cu(II) complexes. We propose the molecular structure of all the studied complexes at the glassy state deduced from EPR and optical spectroscopy results. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Car-borne multichannel gamma-ray spectrometric system model CZD-6

    International Nuclear Information System (INIS)

    Lu Shili; Zhai Yugui; Ma Yanfang; Jiao Cangwen; Zhang Biao

    1998-01-01

    The car-borne multichannel gamma-ray spectrometric system Mode CZD-6 is composed of a HDY-256 of portable multichannel gamma-ray spectrometer developed by the Beijing Research Institute of Uranium Geology and a large volume scintillation detector. the position for each measurement point is determined by the GPS instrument. Its latitude and longitude, as well as measured 256 channels of γ-spectrometric data are collected by a notebook computer, which can show the 256 channels of spectra for each point during measuring processes. The complete system can be loaded in a field car. This system has been used to environmental radioactive monitoring after calibration by airborne radiometric models in Shijiazhuang, Hebei province. A lot of data confirm that the system works stably and reliably, and is a fast and advanced approach for environmental γ-spectrometric monitoring. It can be used not only to determination of contents of natural radioactive elements in environments, but also to monitoring nuclear pollution and emergency treatment in nuclear accidents significantly

  1. Certification of model spectrometric alpha sources (MSAS) and problems of the MSAS system improvement

    International Nuclear Information System (INIS)

    Belyatskij, A.F.; Gejdel'man, A.M.; Egorov, Yu.S.; Nedovesov, V.G.; Chechev, V.P.

    1984-01-01

    Results of certification of standard spectrometric alpha sources (SSAS) of industrial production are presented: methods for certification by main radiation physical parameters: proper halfwidth of α-lines, activity of radionuclides in the source, energies of α-particle emitting sources and relative intensity of different energy α-particle groups - are analysed. The advantage for the SSAS system improvement - a set of model measures for α-radiation, a collection of interconnected data units on physical, engineering and design characteristics of SSAS, methods for their obtaining and determination, on instruments used, is considered

  2. Calculating Equilibrium Constants in the SnCl2-H2O-NaOH System According to Potentiometric Titration Data

    Science.gov (United States)

    Maskaeva, L. N.; Fedorova, E. A.; Yusupov, R. A.; Markov, V. F.

    2018-05-01

    The potentiometric titration of tin chloride SnCl2 is performed in the concentration range of 0.00009-1.1 mol/L with a solution of sodium hydroxide NaOH. According to potentiometric titration data based on modeling equilibria in the SnCl2-H2O-NaOH system, basic equations are generated for the main processes, and instability constants are calculated for the resulting hydroxo complexes and equilibrium constants of low-soluble tin(II) compounds. The data will be of interest for specialists in the field of theory of solutions.

  3. Potentiometric and ab initio studies of acid-base interactions of substituted 4-halo(Cl, Br)pyridine N-oxide systems

    International Nuclear Information System (INIS)

    Gurzynski, Lukasz; Puszko, Aniela; Makowski, Mariusz; Makowska, Joanna; Chmurzynski, Lech

    2006-01-01

    By using the potentiometric method, acidity constants have been determined in systems of tri- and tetra-substituted pyridine N-oxides. The potentiometric measurements in systems of four 4-chloropyridine N-oxide derivatives containing the chlorine atom at position 4 to the NO 2 group and four bromine counterparts were carried out in polar non-aqueous solvents, viz. amphiprotic methanol (MeOH) and aprotic protophilic dimethyl sulfoxide (DMSO). It was found that in all the systems studied the pK a values were readily determinable (as indicated by small standard deviations) in MeOH, whereas in DMSO large standard deviations were obtained making the pK a values either hardly determinable or indeterminable from potentiometric measurements. Furthermore, it was demonstrated that the acidity constants of protonated N-oxides studied in MeOH changed according to the sequence of their acidity constants in water. It was also found that in the polar solvents studied, i.e. in the amphiprotic methanol and the highly basic aprotic dimethyl sulfoxide, the cationic homo-conjugation equlibrium constants could not be determined using potentiometric method. Also, by using ab initio methods at the RHF and MP2 levels and the PCM model, utilizing the Gaussian 6-31++G** basis set, energies and Gibbs free energies of the protonation reactions of the N-oxides have been determined. The energy parameters have been compared with acidity constants of the protonated N-oxides determined by potentiometric titration in methanol to establish a correlation between these approaches

  4. Potentiometric and ab initio studies of acid-base interactions of substituted 4-halo(Cl, Br)pyridine N-oxide systems

    Energy Technology Data Exchange (ETDEWEB)

    Gurzynski, Lukasz [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Puszko, Aniela [Department of Organic Chemistry, School of Economics, Wroclaw (Poland); Makowski, Mariusz [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Makowska, Joanna [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Chmurzynski, Lech [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland)]. E-mail: lech@chem.univ.gda.pl

    2006-12-15

    By using the potentiometric method, acidity constants have been determined in systems of tri- and tetra-substituted pyridine N-oxides. The potentiometric measurements in systems of four 4-chloropyridine N-oxide derivatives containing the chlorine atom at position 4 to the NO{sub 2} group and four bromine counterparts were carried out in polar non-aqueous solvents, viz. amphiprotic methanol (MeOH) and aprotic protophilic dimethyl sulfoxide (DMSO). It was found that in all the systems studied the pK {sub a} values were readily determinable (as indicated by small standard deviations) in MeOH, whereas in DMSO large standard deviations were obtained making the pK {sub a} values either hardly determinable or indeterminable from potentiometric measurements. Furthermore, it was demonstrated that the acidity constants of protonated N-oxides studied in MeOH changed according to the sequence of their acidity constants in water. It was also found that in the polar solvents studied, i.e. in the amphiprotic methanol and the highly basic aprotic dimethyl sulfoxide, the cationic homo-conjugation equlibrium constants could not be determined using potentiometric method. Also, by using ab initio methods at the RHF and MP2 levels and the PCM model, utilizing the Gaussian 6-31++G** basis set, energies and Gibbs free energies of the protonation reactions of the N-oxides have been determined. The energy parameters have been compared with acidity constants of the protonated N-oxides determined by potentiometric titration in methanol to establish a correlation between these approaches.

  5. Potentiometric chip-based multipumping flow system for the simultaneous determination of fluoride, chloride, pH, and redox potential in water samples.

    Science.gov (United States)

    Chango, Gabriela; Palacio, Edwin; Cerdà, Víctor

    2018-08-15

    A simple potentiometric chip-based multipumping flow system (MPFS) has been developed for the simultaneous determination of fluoride, chloride, pH, and redox potential in water samples. The proposed system was developed by using a poly(methyl methacrylate) chip microfluidic-conductor using the advantages of flow techniques with potentiometric detection. For this purpose, an automatic system has been designed and built by optimizing the variables involved in the process, such as: pH, ionic strength, stirring and sample volume. This system was applied successfully to water samples getting a versatile system with an analysis frequency of 12 samples per hour. Good correlation between chloride and fluoride concentration measured with ISE and ionic chromatography technique suggests satisfactory reliability of the system. Copyright © 2018 Elsevier B.V. All rights reserved.

  6. A potentiometric study of (acid+base) equilibria in substituted 4-nitropyridine N-oxide systems in methanol and dimethyl sulfoxide

    International Nuclear Information System (INIS)

    Gurzynski, Lukasz; Puszko, Aniela; Makowski, Mariusz; Chmurzynski, Lech

    2007-01-01

    The acid dissociation constants for cationic acids conjugated with 4-nitropyridine N-oxides have been determined using potentiometric titration method. The measurements in the systems of thirteen 4-nitropyridine N-oxide derivatives were carried out in the polar amphiprotic methanol (MeOH) and in the aprotic protophilic dimethyl sulfoxide (DMSO). Likewise as in the polar aprotic protophobic solvents (acetonitrile, acetone) it was found that in MeOH for all N-oxides studied the pK a values were readily determinable, whereas in DMSO the pK a values were hardly determinable or indeterminable by using the potentiometric method. In addition, just like in our previous investigations it was revealed that the sequence of the pK a values of the cationic acids in methanol is the same as in the water and the values are lower than those determined in acetonitrile and acetone. Also, it was found that the phenomenon of cationic homoconjugation equilibria was not present in the systems involving 4-nitropyridine N-oxide derivatives in both solvents used. Furthermore, protonation energies, ΔE prot , and Gibbs free enthalpies, ΔG prot , in vacuo have been compared with acid dissociation constants (expressed as pK a MeOH values) of the protonated N-oxides determined by potentiometric titration in methanol to establish a correlation between these magnitudes

  7. A potentiometric study of (acid+base) equilibria in substituted 4-nitropyridine N-oxide systems in methanol and dimethyl sulfoxide

    Energy Technology Data Exchange (ETDEWEB)

    Gurzynski, Lukasz [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Puszko, Aniela [Department of Organic Chemistry, School of Economics, Wroclaw (Poland); Makowski, Mariusz [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Chmurzynski, Lech [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland)]. E-mail: lech@chemik.chem.univ.gda.pl

    2007-02-15

    The acid dissociation constants for cationic acids conjugated with 4-nitropyridine N-oxides have been determined using potentiometric titration method. The measurements in the systems of thirteen 4-nitropyridine N-oxide derivatives were carried out in the polar amphiprotic methanol (MeOH) and in the aprotic protophilic dimethyl sulfoxide (DMSO). Likewise as in the polar aprotic protophobic solvents (acetonitrile, acetone) it was found that in MeOH for all N-oxides studied the pK{sub a} values were readily determinable, whereas in DMSO the pK{sub a} values were hardly determinable or indeterminable by using the potentiometric method. In addition, just like in our previous investigations it was revealed that the sequence of the pK{sub a} values of the cationic acids in methanol is the same as in the water and the values are lower than those determined in acetonitrile and acetone. Also, it was found that the phenomenon of cationic homoconjugation equilibria was not present in the systems involving 4-nitropyridine N-oxide derivatives in both solvents used. Furthermore, protonation energies, {delta}E{sub prot}, and Gibbs free enthalpies, {delta}G{sub prot}, in vacuo have been compared with acid dissociation constants (expressed as pK{sub a}{sup MeOH} values) of the protonated N-oxides determined by potentiometric titration in methanol to establish a correlation between these magnitudes.

  8. A Portable Low-Power Acquisition System with a Urease Bioelectrochemical Sensor for Potentiometric Detection of Urea Concentrations.

    Science.gov (United States)

    Ma, Wei-Jhe; Luo, Ching-Hsing; Lin, Jiun-Ling; Chou, Sin-Houng; Chen, Ping-Hung; Syu, Mei-Jywan; Kuo, Shin-Hung; Lai, Shin-Chi

    2016-04-02

    This paper presents a portable low-power battery-driven bioelectrochemical signal acquisition system for urea detection. The proposed design has several advantages, including high performance, low cost, low-power consumption, and high portability. A LT1789-1 low-supply-voltage instrumentation amplifier (IA) was used to measure and amplify the open-circuit potential (OCP) between the working and reference electrodes. An MSP430 micro-controller was programmed to process and transduce the signals to the custom-developed software by ZigBee RF module in wireless mode and UART in able mode. The immobilized urease sensor was prepared by embedding urease into the polymer (aniline-co-o-phenylenediamine) polymeric matrix and then coating/depositing it onto a MEMS-fabricated Au working electrode. The linear correlation established between the urea concentration and the potentiometric change is in the urea concentrations range of 3.16 × 10(-4) to 3.16 × 10(-2) M with a sensitivity of 31.12 mV/log [M] and a precision of 0.995 (R² = 0.995). This portable device not only detects urea concentrations, but can also operate continuously with a 3.7 V rechargeab-le lithium-ion battery (500 mA·h) for at least four days. Accordingly, its use is feasible and even promising for home-care applications.

  9. A Portable Low-Power Acquisition System with a Urease Bioelectrochemical Sensor for Potentiometric Detection of Urea Concentrations

    Directory of Open Access Journals (Sweden)

    Wei-Jhe Ma

    2016-04-01

    Full Text Available This paper presents a portable low-power battery-driven bioelectrochemical signal acquisition system for urea detection. The proposed design has several advantages, including high performance, low cost, low-power consumption, and high portability. A LT1789-1 low-supply-voltage instrumentation amplifier (IA was used to measure and amplify the open-circuit potential (OCP between the working and reference electrodes. An MSP430 micro-controller was programmed to process and transduce the signals to the custom-developed software by ZigBee RF module in wireless mode and UART in able mode. The immobilized urease sensor was prepared by embedding urease into the polymer (aniline-co-o-phenylenediamine polymeric matrix and then coating/depositing it onto a MEMS-fabricated Au working electrode. The linear correlation established between the urea concentration and the potentiometric change is in the urea concentrations range of 3.16 × 10−4 to 3.16 × 10−2 M with a sensitivity of 31.12 mV/log [M] and a precision of 0.995 (R2 = 0.995. This portable device not only detects urea concentrations, but can also operate continuously with a 3.7 V rechargeab-le lithium-ion battery (500 mA·h for at least four days. Accordingly, its use is feasible and even promising for home-care applications.

  10. A Portable Low-Power Acquisition System with a Urease Bioelectrochemical Sensor for Potentiometric Detection of Urea Concentrations

    Science.gov (United States)

    Ma, Wei-Jhe; Luo, Ching-Hsing; Lin, Jiun-Ling; Chou, Sin-Houng; Chen, Ping-Hung; Syu, Mei-Jywan; Kuo, Shin-Hung; Lai, Shin-Chi

    2016-01-01

    This paper presents a portable low-power battery-driven bioelectrochemical signal acquisition system for urea detection. The proposed design has several advantages, including high performance, low cost, low-power consumption, and high portability. A LT1789-1 low-supply-voltage instrumentation amplifier (IA) was used to measure and amplify the open-circuit potential (OCP) between the working and reference electrodes. An MSP430 micro-controller was programmed to process and transduce the signals to the custom-developed software by ZigBee RF module in wireless mode and UART in able mode. The immobilized urease sensor was prepared by embedding urease into the polymer (aniline-co-o-phenylenediamine) polymeric matrix and then coating/depositing it onto a MEMS-fabricated Au working electrode. The linear correlation established between the urea concentration and the potentiometric change is in the urea concentrations range of 3.16 × 10−4 to 3.16 × 10−2 M with a sensitivity of 31.12 mV/log [M] and a precision of 0.995 (R2 = 0.995). This portable device not only detects urea concentrations, but can also operate continuously with a 3.7 V rechargeab-le lithium-ion battery (500 mA·h) for at least four days. Accordingly, its use is feasible and even promising for home-care applications. PMID:27049390

  11. Groundwater Flow Systems at the Nevada Test Site, Nevada: A Synthesis of Potentiometric Contours, Hydrostratigraphy, and Geologic Structures

    Energy Technology Data Exchange (ETDEWEB)

    Fenelon, Joseph M.; Sweetkind, Donald S.; Laczniak, Randell J.

    2010-01-25

    gradients between aquifer types are downward throughout most of the study area; however, flow from the alluvial-volcanic aquifer into the underlying carbonate aquifer, where both aquifers are present, is believed to be minor because of an intervening confining unit. Limited exchange of water between aquifer types occurs by diffuse flow through the confining unit, by focused flow along fault planes, or by direct flow where the confining unit is locally absent. Interflow between regional aquifers is evaluated and mapped to define major flow paths. These flow paths delineate tributary flow systems, which converge to form intermediate and regional flow systems. The implications of these flow systems in controlling transport of radionuclides away from the underground test areas at the Nevada Test Site are briefly discussed. Additionally, uncertainties in the delineation of aquifers, the development of potentiometric contours, and the identification of flow systems are identified and evaluated. Eleven tributary flow systems and three larger flow systems are mapped in the Nevada Test Site area. Flow systems within the alluvial-volcanic aquifer dominate the western half of the study area, whereas flow systems within the carbonate aquifer are most prevalent in the southeastern half of the study area. Most of the flow in the regional alluvial-volcanic aquifer that moves through the underground testing area on Pahute Mesa is discharged to the land surface at springs and seeps in Oasis Valley. Flow in the regional carbonate aquifer is internally compartmentalized by major geologic structures, primarily thrust faults, which constrain flow into separate corridors. Contaminants that reach the regional carbonate aquifer from testing areas in Yucca and Frenchman Flats flow toward downgradient discharge areas through the Alkali Flat-Furnace Creek Ranch or Ash Meadows flow systems and their tributaries.

  12. Groundwater Flow Systems at the Nevada Test Site, Nevada: A Synthesis of Potentiometric Contours, Hydrostratigraphy, and Geologic Structures

    Science.gov (United States)

    Fenelon, Joseph M.; Sweetkind, Donald S.; Laczniak, Randell J.

    2010-01-01

    gradients between aquifer types are downward throughout most of the study area; however, flow from the alluvial-volcanic aquifer into the underlying carbonate aquifer, where both aquifers are present, is believed to be minor because of an intervening confining unit. Limited exchange of water between aquifer types occurs by diffuse flow through the confining unit, by focused flow along fault planes, or by direct flow where the confining unit is locally absent. Interflow between regional aquifers is evaluated and mapped to define major flow paths. These flow paths delineate tributary flow systems, which converge to form intermediate and regional flow systems. The implications of these flow systems in controlling transport of radionuclides away from the underground test areas at the Nevada Test Site are briefly discussed. Additionally, uncertainties in the delineation of aquifers, the development of potentiometric contours, and the identification of flow systems are identified and evaluated. Eleven tributary flow systems and three larger flow systems are mapped in the Nevada Test Site area. Flow systems within the alluvial-volcanic aquifer dominate the western half of the study area, whereas flow systems within the carbonate aquifer are most prevalent in the southeastern half of the study area. Most of the flow in the regional alluvial-volcanic aquifer that moves through the underground testing area on Pahute Mesa is discharged to the land surface at springs and seeps in Oasis Valley. Flow in the regional carbonate aquifer is internally compartmentalized by major geologic structures, primarily thrust faults, which constrain flow into separate corridors. Contaminants that reach the regional carbonate aquifer from testing areas in Yucca and Frenchman Flats flow toward downgradient discharge areas through the Alkali Flat-Furnace Creek Ranch or Ash Meadows flow systems and their tributaries.

  13. Potentiometric determination of molybdenum

    International Nuclear Information System (INIS)

    Rusina, O.N.; Gorbatkova, B.Kh.

    1977-01-01

    Potentiometric titration by lead acetate is used to determine molybdenum in the form of molybdate ions. The behaviour of bimetallic electrode couples, i.e. tungsten-lead, platinum-lead, lead-carbon electrode, molybdenum-carbon electrode platinum-molibdenum has been investigated. The greatest jump of the potential in the finite point is observed for platinum-molybdenum electrode couple (150 mV/ml at pH 4.0-5.5). The limiting concentration of molybdenum in potentiometric titration by lead acetate is 2.8x10 -4 M. The measurements are accurate to within +-0.1%

  14. Potentiometric titration of plutonium

    International Nuclear Information System (INIS)

    Silver, G.L.

    1978-01-01

    In the potentiometric titration of plutonium(III), it has been customary to take the equivalence point as the inflection point on a plot of potential vs. volume of titrant. It have not been, however, demonstrated, that the stoichiometric end point corresponds to the inflection point. Suggestions are made according to which these points may not correspond in the potentiometric titration of plutonium(III), as these titrations are ordinarily concluded in a period of time which is short compared to the time required for valence state rearrangement through disproportionation. (T.G.)

  15. Emission spectrometric isotope analyzer

    International Nuclear Information System (INIS)

    Mauersberger, K.; Meier, G.; Nitschke, W.; Rose, W.; Schmidt, G.; Rahm, N.; Andrae, G.; Krieg, D.; Kuefner, W.; Tamme, G.; Wichlacz, D.

    1982-01-01

    An emission spectrometric isotope analyzer has been designed for determining relative abundances of stable isotopes in gaseous samples in discharge tubes, in liquid samples, and in flowing gaseous samples. It consists of a high-frequency generator, a device for defined positioning of discharge tubes, a grating monochromator with oscillating slit and signal converter, signal generator, window discriminator, AND connection, read-out display, oscillograph, gas dosing device and chemical conversion system with carrier gas source and vacuum pump

  16. Characterization of HPGe gamma spectrometric detectors systems for Instrumental Neutron Activation Analysis (INAA) at the Colombian Geological Survey

    Energy Technology Data Exchange (ETDEWEB)

    Sierra, O., E-mail: osierra@sgc.gov.co; Parrado, G., E-mail: gparrado@sgc.gov.co; Cañón, Y.; Porras, A.; Alonso, D.; Herrera, D. C.; Peña, M., E-mail: mlpena@sgc.gov.co; Orozco, J. [Colombian Geological Survey, Nuclear Affairs Technical Division, Neutron Activation Analysis Laboratory, Bogota D. C. (Colombia)

    2016-07-07

    This paper presents the progress made by the Neutron Activation Analysis (NAA) laboratory at the Colombian Geological Survey (SGC in its Spanish acronym), towards the characterization of its gamma spectrometric systems for Instrumental Neutron Activation Analysis (INAA), with the aim of introducing corrections to the measurements by variations in sample geometry. Characterization includes the empirical determination of the interaction point of gamma radiation inside the Germanium crystal, through the application of a linear model and the use of a fast Monte Carlo N-Particle (MCNP) software to estimate correction factors for differences in counting efficiency that arise from variations in sample density between samples and standards.

  17. Units for designing multidetector system for spectrometric data storage on the base of the 16Kx24 bit memory device

    International Nuclear Information System (INIS)

    Vagov, V.A.; Korobchenko, M.L.; Sirotin, A.P.

    1985-01-01

    Main units of the system for spectrometric data accumulation on the base of the 16Kx24 bit memory device are considered. Input units: counter unit and unit for organization of analysis are described. The applied method for multiplexing data removed into the counter unit permits to essentially reduce hardware loading. Application of some special functions in the unit for analysis organization simplifies data accumulation control to a large extent. The unit for analysis organization allows application of the memory with an address field up to 64K

  18. Using Potentiometric Free Drug Sensors to Determine the Free Concentration of Ionizable Drugs in Colloidal Systems

    DEFF Research Database (Denmark)

    Tran, Thuy; Chakraborty, Anjan; Xi, Xi

    2018-01-01

    The present study investigates the use of free drug sensors (FDS) to measure free ionized drug concentrations in colloidal systems, including micellar solutions, emulsions, and lipid formulations during in vitro lipolysis. Diphenhydramine hydrochloride (DPH) and loperamide hydrochloride (LOP) wer...

  19. SHORT COMMUNICATION POTENTIOMETRIC DETERMINATION ...

    African Journals Online (AJOL)

    a

    SHORT COMMUNICATION. POTENTIOMETRIC DETERMINATION OF K+ IONS USING A K+-SELECTIVE. ELECTRODE WITH MACROCYCLIC LIQUID MEMBRANE. Cezar Spinu*, Marian Isvoranu, Maria Pleniceanu and Cristian Tigae. Faculty of Chemistry, University of Craiova, A.I. Cuza 13, Craiova, Romania. (Received ...

  20. Potentiometric flow injection system for determination of reductants using a polymeric membrane permanganate ion-selective electrode based on current-controlled reagent delivery.

    Science.gov (United States)

    Song, Wenjing; Ding, Jiawang; Liang, Rongning; Qin, Wei

    2011-10-17

    A polymeric membrane permanganate-selective electrode has been developed as a current-controlled reagent release system for potentiometric detection of reductants in flow injection analysis. By applying an external current, diffusion of permanganate ions across the polymeric membrane can be controlled precisely. The permanganate ions released at the sample-membrane interface from the inner filling solution of the electrode are consumed by reaction with a reductant in the sample solution thus changing the measured membrane potential, by which the reductant can be sensed potentiometrically. Ascorbate, dopamine and norepinephrine have been employed as the model reductants. Under the optimized conditions, the potential peak heights are proportional to the reductant concentrations in the ranges of 1.0×10(-5) to 2.5×10(-7)M for ascorbate, of 1.0×10(-5) to 5.0×10(-7)M for dopamine, and of 1.0×10(-5) to 5.0×10(-7)M for norepinephrine, respectively with the corresponding detection limits of 7.8×10(-8), 1.0×10(-7) and 1.0×10(-7)M. The proposed system has been successfully applied to the determination of reductants in pharmaceutical preparations and vegetables, and the results agree well with those of iodimetric analysis. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. Redox equilibria in the In(III)-In(I)-In system in aqueous KBr solutions, I. potentiometric and coulometric study

    International Nuclear Information System (INIS)

    Malyszko, E.; Malyszko, J.

    1993-01-01

    The reproportionation of In(I) ions in acidic potassium bromide solutions was studied by means of the coulometric and potentiometric method. The formal potentials of the In(III)/In(I), In(III)/In and In(I)/In redox couples as well as the equilibrium constants of the reaction In(III) + 2 In 3 In(I) were determined at a background electrolyte concentration ranging from 1 to 4 mol dm -3 . Based on the experimental results, a scheme of the reproportionation reaction was proposed with regard to the participation of bromide ions. In addition, the diffusion coefficient of In(I) ions was determined using the chronopotentiometric technique

  2. Pseudo-indicator behaviour of platinum electrode explored for the potentiometric estimation of non-redox systems.

    Science.gov (United States)

    Raashid, Syed; Chat, Oyais Ahmad; Rizvi, Masood A; Bhat, Mohsin Ahmad; Khan, Badruddin

    2012-11-15

    A pseudo-indicator electrode based potentiometric method for estimation of non-redox metal ions is presented. In the proposed method, nature and concentration specific impact of analyte over the redox potential of ideally polarisable Pt/pregenerated-redox-couple interface forms the basis of quantification. Utility of the method in estimation of six non-redox metal ions viz. Zn(2+), Cu(2+), Ni(2+), Cd(2+), Pb(2+), Al(3+) in the concentration range of 10(-1)-10(-3) moldm(-3), individually and as binary mixtures is also presented. Three types of potentiometric behaviours, which we ascribe to the nature specific thermodynamic and kinetic aspects of metal-EDTA binding, were observed. While Cu(2+), Ni(2+), Pb(2+) and Al(3+) were found to bind EDTA efficiently, without exchanging Fe(3+); Zn(2+) and Cd(2+) were observed to replace Fe(3+) from EDTA. In contrast, Ca(2+) and Mg(2+) were found to show no binding affinity to EDTA in the pH range employed in the present work. The proposed method was also used to explore the reversibility and the Nernestian behaviour of ferricyanide/ferrocyanide redox couple through spectroelectrochemical titration of Zn(2+) with ferrocyanide. The presented method is presaged to be a reliable and low cost future replacement for costly and delicate ion selective electrodes (ISE) in the estimation of non-redox species like Zn(2+), Cu(2+), etc. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. A potentiometric study of molecular heteroconjugation equilibria in (n-butylamine+acetic acid) systems in binary (acetonitrile +1,4-dioxane) solvent mixtures

    International Nuclear Information System (INIS)

    Czaja, Malgorzata; Makowski, Mariusz; Chmurzynski, Lech

    2006-01-01

    By using the potentiometric method the following quantities have been determined: acidity constants of molecular acid, K a (HA), of cationic acid, K a (BH + ), anionic and cationic homoconjugation constants, K AHA - and K BHB + , respectively, as well as molecular heteroconjugation constants, K AHB , in (n-butylamine+acetic acid) systems without proton transfer in binary (acetonitrile+1,4-dioxane), AN+D, solvent mixtures. The results of these measurements have shown that the magnitudes of the molecular heteroconjugation constants do not depend on the 1,4-dioxane content in the mixed solvent, i.e., on solvent polarity. It has also been found that in the (acid+base) systems without proton transfer, the manner of carrying out the titration (direct B+HA vs. reverse HA+B) does not affect the magnitudes of the molecular heteroconjugation constants

  4. A potentiometric study of molecular heteroconjugation equilibria in (n-butylamine+acetic acid) systems in binary (acetonitrile +1,4-dioxane) solvent mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Czaja, Malgorzata [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Makowski, Mariusz [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Chmurzynski, Lech [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland)]. E-mail: lech@chem.univ.gda.pl

    2006-05-15

    By using the potentiometric method the following quantities have been determined: acidity constants of molecular acid, K{sub a}(HA), of cationic acid, K{sub a}(BH{sup +}), anionic and cationic homoconjugation constants, K{sub AHA{sup -}} and K{sub BHB{sup +}}, respectively, as well as molecular heteroconjugation constants, K{sub AHB}, in (n-butylamine+acetic acid) systems without proton transfer in binary (acetonitrile+1,4-dioxane), AN+D, solvent mixtures. The results of these measurements have shown that the magnitudes of the molecular heteroconjugation constants do not depend on the 1,4-dioxane content in the mixed solvent, i.e., on solvent polarity. It has also been found that in the (acid+base) systems without proton transfer, the manner of carrying out the titration (direct B+HA vs. reverse HA+B) does not affect the magnitudes of the molecular heteroconjugation constants.

  5. Potentiometric investigations of (acid+base) equilibria in (n-butylamine+acetic acid) systems in binary (acetone+cyclohexane) solvent mixtures

    International Nuclear Information System (INIS)

    Czaja, MaIgorzata; Kozak, Anna; Makowski, Mariusz; Chmurzynski, Lech

    2005-01-01

    By using the potentiometric titration method, standard equilibrium constants have been determined of acid dissociation of molecular acid, K a (HA), cationic acid, K a (BH + ), of anionic and cationic homoconjugation, K AHA - andK BHB + , respectively, and of molecular heteroconjugation, K AHB (K BHA ), in (acid+base) systems without proton transfer consisting of n-butylamine and acetic acid in binary (acetone+cyclohexane) solvent mixtures. The results have shown that both the pK a (HA) and pK a (BH + ), as well as lgK AHA - values change non-linearly as a function of composition of the solvent mixture. On the other hand, standard molecular heteroconjugation constants without proton transfer do not depend on the cyclohexane content in the mixture, i.e. on solvent polarity

  6. Potentiometric investigations of (acid+base) equilibria in (n-butylamine+acetic acid) systems in binary (acetone+cyclohexane) solvent mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Czaja, MaIgorzata [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Kozak, Anna [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Makowski, Mariusz [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Chmurzynski, Lech [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland)]. E-mail: lech@chem.univ.gda.pl

    2005-08-15

    By using the potentiometric titration method, standard equilibrium constants have been determined of acid dissociation of molecular acid, K{sub a}(HA), cationic acid, K{sub a}(BH{sup +}), of anionic and cationic homoconjugation, K{sub AHA{sup -}}andK{sub BHB{sup +}}, respectively, and of molecular heteroconjugation, K{sub AHB} (K{sub BHA}), in (acid+base) systems without proton transfer consisting of n-butylamine and acetic acid in binary (acetone+cyclohexane) solvent mixtures. The results have shown that both the pK{sub a}(HA) and pK{sub a}(BH{sup +}), as well as lgK{sub AHA{sup -}} values change non-linearly as a function of composition of the solvent mixture. On the other hand, standard molecular heteroconjugation constants without proton transfer do not depend on the cyclohexane content in the mixture, i.e. on solvent polarity.

  7. Thermodynamic investigation of the ternary mixed aqueous electrolyte (MgCl{sub 2} + MgSO{sub 4}) system by potentiometric method at T = 298.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Bagherinia, Mohammad A., E-mail: mabagherinia@yahoo.com [Department of Chemistry, Faculty of Science, Lahijan Branch, Islamic Azad University, Lahijan (Iran, Islamic Republic of); Giahi, Masoud; Pournaghdy, Mohammad; Vaghar, Gholam R. [Department of Chemistry, Faculty of Science, Lahijan Branch, Islamic Azad University, Lahijan (Iran, Islamic Republic of)

    2012-01-15

    Highlights: > In this study we investigated the thermodynamic properties of MgCl{sub 2} + MgSO{sub 4} + H{sub 2}O. > The method used in this work was potentiometric method. > Mg-ISE and the Ag/AgCl electrodes used in this work had a good Nernst response. > The experimental results obeyed the Harned rule. > The Pitzer model could be used to describe this ternary system satisfactorily. - Abstract: This work reports the results of thermodynamic investigation of the ternary mixed-electrolyte system (MgCl{sub 2} + MgSO{sub 4} + H{sub 2}O). The investigation was performed based on Pitzer ion interaction model by using the potentiometric technique at T = 298.15 K. The mean activity coefficients of MgCl{sub 2} in the mixed aqueous electrolyte system were determined on the galvanic cell without liquid junction of the type: Mg-ISE|MgCl{sub 2} (m{sub A}), MgSO{sub 4} (m{sub B}), H{sub 2}O|Ag/AgCl over total ionic strengths from (0.001 to 8.000) mol . kg{sup -1} for different series of salt ratio r (r=m{sub MgCl{sub 2}}/m{sub MgSO{sub 4}}=2.5,5.0,7.5,10.0,15.0 and pure MgCl{sub 2}). The PVC based magnesium ion-selective electrode (Mg-ISE) and the Ag/AgCl electrode used in this work were made in our laboratory and had a reasonably good Nernst response. The experimental results obeyed the Harned rule, and the Pitzer model could be used to describe this ternary system satisfactorily. Pitzer ion-interaction parameters for mixed salts were determined for this system. Then, these parameters ({theta}{sub ClSO{sub 4}}=0.0252{+-}0.0042, {psi}{sub MgClSO{sub 4}}=-0.0049{+-}0.0003) were used to calculate the values of the mean activity coefficients of MgSO{sub 4}, the osmotic coefficients of water ({phi}) and the excess Gibbs free energies of solution (G{sup E}) for the whole series of the studied electrolyte systems.

  8. Potentiometric titration with polarized electrodes

    International Nuclear Information System (INIS)

    Chikryzova, E.G.

    1977-01-01

    Based on the analysis of the works carried out during 1911-75 consideration is given to the present state of the method of potentiometric titration with polarized electrodes. The material is generalized in the tabular form indicating the elments of interest, titration conditions and the objects to be analyzed. The list and classification of the potentiometric titration methods intended for determining organic and inorganic substances are presented

  9. Spectrometric techniques 4

    CERN Document Server

    Vanasse, George A

    2013-01-01

    Spectrometric Techniques, Volume IV discusses three widely diversified areas of spectrometric techniques. The book focuses on three spectrometric methods. Chapter 1 discusses the phenomenology and applications of Coherent Anti-Stokes Raman Spectroscopy (CARS), the most commonly used optical technique that exploit the Raman effect. The second chapter is concerned with diffraction gratings and mountings for the Vacuum Ultraviolet Spectral Region. Chapter 3 accounts the uses of mass spectrometry, detectors, types of spectrometers, and ion sources. Physicists and chemists will find the book a go

  10. Detector system for in-situ spectrometric analysis of 241Am and Pu in soil

    International Nuclear Information System (INIS)

    Kirby, J.A.; Anspaugh, L.R.; Phelps, P.L.; Amantrout, G.A.; Sawyer, D.

    1975-01-01

    This system for quantitative analysis of Pu in soil via 241 Am has four 2.5-mm high-purity Ge detectors of 33 cm 2 total detecting surface area. These detectors are paralleled by gating circuitry to avoid the degradation of energy resolution associated with electronic output summing. In field tests the system was approximately three times as sensitive as a 70-cm 3 Ge(Li) detector and approximately an order of magnitude more sensitive than the FIDLER system

  11. New miniaturized alpha/beta spectrometric system for the surface contamination monitoring and radon personal dosimeter

    International Nuclear Information System (INIS)

    Streil, T.; Oeser, V.; Holfeld, G.

    1998-01-01

    The heart of the new miniaturized alpha/beta spectroscopic system is a Smart Card MCA having a 12 bit resolution and a 32 bit memory for each channel with the size of a cheque card. The system consists of a single or up to 12 alpha spectrometers in a battery powered casing with connectors for direct detector/amplifier module plugging. Surface contamination in the order of 1 Bq/cm 2 of 239 Pu can be measured. (M.D.)

  12. Simulation for photon detection in spectrometric system of high purity (HPGe) using MCNPX code

    International Nuclear Information System (INIS)

    Correa, Guilherme Jorge de Souza

    2013-01-01

    The Brazilian National Commission of Nuclear Energy defines parameters for classification and management of radioactive waste in accordance with the activity of materials. The efficiency of a detection system is crucial to determine the real activity of a radioactive source. When it's possible, the system's calibration should be performed using a standard source. Unfortunately, there are only a few cases that it can be done this way, considering the difficulty of obtaining appropriate standard sources for each type of measurement. So, computer simulations can be performed to assist in calculating of the efficiency of the system and, consequently, also auxiliary the classification of radioactive waste. This study aims to model a high purity germanium (HPGe) detector with MCNPX code, approaching the spectral values computationally obtained of the values experimentally obtained for the photopeak of 137 Cs. The approach will be made through changes in outer dead layer of the germanium crystal modeled. (author)

  13. Automated on-line liquid–liquid extraction system for temporal mass spectrometric analysis of dynamic samples

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, Kai-Ta; Liu, Pei-Han [Department of Applied Chemistry, National Chiao Tung University, 1001 University Rd, Hsinchu, 300, Taiwan (China); Urban, Pawel L. [Department of Applied Chemistry, National Chiao Tung University, 1001 University Rd, Hsinchu, 300, Taiwan (China); Institute of Molecular Science, National Chiao Tung University, 1001 University Rd, Hsinchu, 300, Taiwan (China)

    2015-09-24

    Most real samples cannot directly be infused to mass spectrometers because they could contaminate delicate parts of ion source and guides, or cause ion suppression. Conventional sample preparation procedures limit temporal resolution of analysis. We have developed an automated liquid–liquid extraction system that enables unsupervised repetitive treatment of dynamic samples and instantaneous analysis by mass spectrometry (MS). It incorporates inexpensive open-source microcontroller boards (Arduino and Netduino) to guide the extraction and analysis process. Duration of every extraction cycle is 17 min. The system enables monitoring of dynamic processes over many hours. The extracts are automatically transferred to the ion source incorporating a Venturi pump. Operation of the device has been characterized (repeatability, RSD = 15%, n = 20; concentration range for ibuprofen, 0.053–2.000 mM; LOD for ibuprofen, ∼0.005 mM; including extraction and detection). To exemplify its usefulness in real-world applications, we implemented this device in chemical profiling of pharmaceutical formulation dissolution process. Temporal dissolution profiles of commercial ibuprofen and acetaminophen tablets were recorded during 10 h. The extraction-MS datasets were fitted with exponential functions to characterize the rates of release of the main and auxiliary ingredients (e.g. ibuprofen, k = 0.43 ± 0.01 h{sup −1}). The electronic control unit of this system interacts with the operator via touch screen, internet, voice, and short text messages sent to the mobile phone, which is helpful when launching long-term (e.g. overnight) measurements. Due to these interactive features, the platform brings the concept of the Internet-of-Things (IoT) to the chemistry laboratory environment. - Highlights: • Mass spectrometric analysis normally requires sample preparation. • Liquid–liquid extraction can isolate analytes from complex matrices. • The proposed system automates

  14. Automated on-line liquid–liquid extraction system for temporal mass spectrometric analysis of dynamic samples

    International Nuclear Information System (INIS)

    Hsieh, Kai-Ta; Liu, Pei-Han; Urban, Pawel L.

    2015-01-01

    Most real samples cannot directly be infused to mass spectrometers because they could contaminate delicate parts of ion source and guides, or cause ion suppression. Conventional sample preparation procedures limit temporal resolution of analysis. We have developed an automated liquid–liquid extraction system that enables unsupervised repetitive treatment of dynamic samples and instantaneous analysis by mass spectrometry (MS). It incorporates inexpensive open-source microcontroller boards (Arduino and Netduino) to guide the extraction and analysis process. Duration of every extraction cycle is 17 min. The system enables monitoring of dynamic processes over many hours. The extracts are automatically transferred to the ion source incorporating a Venturi pump. Operation of the device has been characterized (repeatability, RSD = 15%, n = 20; concentration range for ibuprofen, 0.053–2.000 mM; LOD for ibuprofen, ∼0.005 mM; including extraction and detection). To exemplify its usefulness in real-world applications, we implemented this device in chemical profiling of pharmaceutical formulation dissolution process. Temporal dissolution profiles of commercial ibuprofen and acetaminophen tablets were recorded during 10 h. The extraction-MS datasets were fitted with exponential functions to characterize the rates of release of the main and auxiliary ingredients (e.g. ibuprofen, k = 0.43 ± 0.01 h"−"1). The electronic control unit of this system interacts with the operator via touch screen, internet, voice, and short text messages sent to the mobile phone, which is helpful when launching long-term (e.g. overnight) measurements. Due to these interactive features, the platform brings the concept of the Internet-of-Things (IoT) to the chemistry laboratory environment. - Highlights: • Mass spectrometric analysis normally requires sample preparation. • Liquid–liquid extraction can isolate analytes from complex matrices. • The proposed system automates the

  15. Data set for mass spectrometric analysis of recombinant human serum albumin from various expression systems

    Directory of Open Access Journals (Sweden)

    Daryl G.S. Smith

    2015-09-01

    Full Text Available Human serum albumin (HSA is a versatile and important protein for the pharmaceutical industry (Fanali et al., Mol. Aspects Med. 33(3 (2012 209–290. Due to the potential transmission of pathogens from plasma sourced albumin, numerous expression systems have been developed to produce recombinant HSA (rHSA (Chen et al., Biochim. Biophys. Acta (BBA—Gen. Subj. 1830(12 (2013 5515–5525; Kobayashi, Biologicals 34(1 (2006 55–59. Based on our previous study showing increased glycation of rHSA expressed in Asian rice (Frahm et al., J. Phys. Chem. B 116(15 (2012 4661–4670, both supplier-to-supplier and lot-to-lot variability of rHSAs from a number of expression systems were evaluated using reversed phase liquid chromatography linked with MS and MS/MS analyses. The data are associated with the research article ‘Determination of Supplier-to-Supplier and Lot-to-Lot Variability in Glycation of Recombinant Human Serum Albumin Expressed in Oryza sativa’ where further analysis of rHSA samples with additional biophysical methods can be found (Frahm et al., PLoS ONE 10(9 (2014 e109893. We determined that all rHSA samples expressed in rice showed elevated levels of arginine and lysine hexose glycation compared to rHSA expressed in yeast, suggesting that the extensive glycation of the recombinant proteins is a by-product of either the expression system or purification process and not a random occurrence.

  16. Analog-to-digital conversion of spectrometric data in information-control systems of activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mamonov, E I

    1972-01-01

    Analog-digital conversion (ADC) techniques in nuclear radiation spectrometer channels is a most important link of information control systems in activation analysis. For the development of the ADC of spectrometer channels logico-structural methods of increasing the capacity, procedures for boosting frequency modes and improving the accuracy are promising. Procedures are suggested for increasing the ADC capacity. Insufficient stability and noticeable non-linearity of the spectrometer channel can be corrected at the information processing stage if their regularities are known. Capacity limitations make the development of ADC featuring high stability, capacity and linearity quite urgent.

  17. Preparation, spectrometric analysis and determination of the electrochemical transport characteristics of uranium (IV) in aqueous systems

    International Nuclear Information System (INIS)

    Schwarzer, W.G.

    1985-01-01

    A process for the quantitative development of uranium-(IV) solutions in nitric and perchloric acid media was developed. After appropriate concentration setting of the solutions, the conductivity of the uranium (IV) in the dependence on concentration were analysed. The conversion of the measuring results on the standard system water was done by means of a conductivity theory; this allows a comparison with the conductivity data of other ions. The conductivity calculated, at an ion strength I tending to zero, provided the suitable data for the ion mobility and the transference number. (orig./PW) [de

  18. Reconstruction of neutron spectra using neural networks starting from the Bonner spheres spectrometric system

    International Nuclear Information System (INIS)

    Ortiz R, J.M.; Martinez B, M.R.; Arteaga A, T.; Vega C, H.R.; Hernandez D, V.M.; Manzanares A, E.

    2005-01-01

    The artificial neural networks (RN) have been used successfully to solve a wide variety of problems. However to determine an appropriate set of values of the structural parameters and of learning of these, it continues being even a difficult task. Contrary to previous works, here a set of neural networks is designed to reconstruct neutron spectra starting from the counting rates coming from the detectors of the Bonner spheres system, using a systematic and experimental strategy for the robust design of multilayer neural networks of the feed forward type of inverse propagation. The robust design is formulated as a design problem of Taguchi parameters. It was selected a set of 53 neutron spectra, compiled by the International Atomic Energy Agency, the counting rates were calculated that would take place in a Bonner spheres system, the set was arranged according to the wave form of those spectra. With these data and applying the Taguchi methodology to determine the best parameters of the network topology, it was trained and it proved the same one with the spectra. (Author)

  19. Towards an automatic lab-on-valve-ion mobility spectrometric system for detection of cocaine abuse.

    Science.gov (United States)

    Cocovi-Solberg, David J; Esteve-Turrillas, Francesc A; Armenta, Sergio; de la Guardia, Miguel; Miró, Manuel

    2017-08-25

    A lab-on-valve miniaturized system integrating on-line disposable micro-solid phase extraction has been interfaced with ion mobility spectrometry for the accurate and sensitive determination of cocaine and ecgonine methyl ester in oral fluids. The method is based on the automatic loading of 500μL of oral fluid along with the retention of target analytes and matrix clean-up by mixed-mode cationic/reversed-phase solid phase beads, followed by elution with 100μL of 2-propanol containing (3% v/v) ammonia, which are online injected into the IMS. The sorptive particles are automatically discarded after every individual assay inasmuch as the sorptive capacity of the sorbent material is proven to be dramatically deteriorated with reuse. The method provided a limit of detection of 0.3 and 0.14μgL -1 for cocaine and ecgonine methyl ester, respectively, with relative standard deviation values from 8 till 14% with a total analysis time per sample of 7.5min. Method trueness was evaluated by analyzing oral fluid samples spiked with cocaine at different concentration levels (1, 5 and 25μgL -1 ) affording relative recoveries within the range of 85±24%. Fifteen saliva samples were collected from volunteers and analysed following the proposed automatic procedure, showing a 40% cocaine occurrence with concentrations ranging from 1.3 to 97μgL -1 . Field saliva samples were also analysed by reference methods based on lateral flow immunoassay and gas chromatography-mass spectrometry. The application of this procedure to the control of oral fluids of cocaine consumers represents a step forward towards the development of a point-of-care cocaine abuse sensing system. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Titulações potenciométricas de cátions metálicos tendo como eletrodo indicador o sistema Cu/Cu(II-EDTA Potentiometric titrations of metal cations with edta using the Cu/Cu(II-EDTA system as indicator electrode

    Directory of Open Access Journals (Sweden)

    Paulo H. Pereira da Silva

    2008-01-01

    Full Text Available In potentiometric titrations of metal cations with EDTA the Hg/HgY2- system is usually used to detect the end point. However, the use of mercury has been discouraged in analytical procedures due to its toxicity. In this work the Cu/CuY2- system was used as indicator electrode for potentiometric titrations of some metal cations with EDTA. The solutions of Cu2+, Cd2+, Mn2+, Co2+ and Zn2+ were titrated with Na2EDTA solution in the presence of a small concentration of the CuY2- complex using a copper wire as indicator electrode. The potentiometric titrations with the Cu/CuY2- system showed good correlation when compared with an Hg/HgY2- system.

  1. Spectrometric techniques 3

    CERN Document Server

    Vanasse, George A

    2013-01-01

    Spectrometric Techniques, Volume III presents the applications of spectrometric techniques to atmospheric and space studies. This book reviews the spectral data processing and analysis techniques that are of broad applicability.Organized into five chapters, this volume begins with an overview of the instrumentation used for obtaining field data. This text then reviews the contribution that space-borne spectroscopy in the thermal IR has made to the understanding of the planets. Other chapters consider the instruments that have recorded the planetary emission spectra. This book discusses as well

  2. Potentiometric-surface altitude of the confined aquifer, Wood River Valley aquifer system, south-central Idaho, October 2012.

    Data.gov (United States)

    Department of the Interior — Water levels in 93 wells completed in the Wood River Valley aquifer system were measured during October 22–24, 2012; these wells are part of a network established...

  3. Titulador potenciométrico automatizado baseado em sistema de fluxo monossegmentado Automated potentiometric titrator based in monosegmented flow system

    Directory of Open Access Journals (Sweden)

    Edgard Moreira Ganzarolli

    1999-02-01

    Full Text Available A new automated system for acid-base flow titrations is proposed. In the operation mode, several sample to titrant volumetric ratios are injected in an air segmented plug. Five three way solenoid valves and three acrilic junctions, assembled in a hidrodynamic injection system, were accountable for the monosegmented reagents plug formation. A turbulent flow reactor was used for a perfect mix of reagents in the plug. The detector system employed a glass combined electrode fitted in an acrilic holder. Titrations of hydrochloric, nitric and acetic acids, in several concentrations, were performed with standard sodium hidroxide, for evaluation of the efficiency of the system. The relative standard deviation of the determinations was about ±0,5% and each titration was carried out in 3-4 minutes. A Quick BASIC 4.5® program was developed for the titrator control.

  4. Thermodynamic studies of (RbF + RbCl + H2O) and (CsF + CsCl + H2O) ternary systems from potentiometric measurements at T = 298.2 K

    International Nuclear Information System (INIS)

    Huang, Xiaoting; Li, Shu’ni; Zhai, Quanguo; Jiang, Yucheng; Hu, Mancheng

    2016-01-01

    Graphical abstract: Thermodynamic properties, such as mean activity coefficients, osmotic coefficients and excess Gibbs free energies, of the RbF + RbCl + H 2 O and CsF + CsCl + H 2 O ternary systems were determined from potentiometric measurement at 298.2 K. The Pitzer model and the Harned rule were used to fit the experimental data. - Highlights: • Thermodynamic properties of RbF + RbCl + H 2 O and CsF + CsCl + H 2 O ternary systems were determined. • The Pitzer model and the Harned rule were used to correlate the experimental data. • The mean activity coefficients, osmotic coefficients, and the excess Gibbs free energy were also obtained. - Abstract: Thermodynamic properties of (RbF + RbCl + H 2 O) and (CsF + CsCl + H 2 O) systems were determined by the potentiometric method for different ionic strength fractions y B of RbCl/CsCl at 298.2 K. The Pitzer model and the Harned rule were used to fit the experimental values. The Pitzer mixing parameters and the Harned coefficients were evaluated. In addition, the mean ionic activity coefficients of RbF/CsF and RbCl/CsCl, the osmotic coefficients, and the excess Gibbs energies of the systems studied were calculated.

  5. Marine gamma spectrometric survey

    International Nuclear Information System (INIS)

    Kostoglodov, V.V.

    1979-01-01

    Presented are theoretical problems physical and geochemical prerequisites and possibilities of practical application of the method of continuous submarine gamma-spectrometric survey and radiometric survey destined for rapid study of the surface layer of marine sediments. Shown is high efficiency and advantages of this method in comparison with traditional and widely spread in marine geology methods of bottom sediments investigation

  6. Mobile spectrometric laboratory

    International Nuclear Information System (INIS)

    Isajenko, K.A.; Lipinski, P.

    2002-01-01

    The article presents the Mobile Spectrometric Laboratory used by Central Laboratory for Radiological Protection since year 2000. The equipment installed in the Mobile Laboratory and its uses is described. The results of international exercises and intercalibrations, in which the Laboratory participated are presented. (author)

  7. Polymeric matrix membrane sensors for stability-indicating potentiometric determination of oxybutynin hydrochloride and flavoxate hydrochloride urogenital system drugs.

    Science.gov (United States)

    Heba, Mohamed; Ramadan, Nesrin; El-Laithy, Moustafa

    2008-01-01

    Four polyvinyl chloride (PVC) matrix membrane electrodes responsive to 2 drugs affecting the urogenital system--oxybutynin hydrochloride (OX) and flavoxate hydrochloride (FX)--were developed, described, and characterized. A precipitation-based technique with tungstophosphate (TP) and ammonium reineckate (R) anions as electroactive materials in a PVC matrix with an OX cation was used for electrode 1 and 2 fabrication, respectively. Electrode 3 and 4 fabrication was based on use of the precipitation technique of FX cation with tetrakis (4-chlorophenyl) borate and R anions as electroactive materials. Fast and stable Nernstian responses in the range 1 x 10(-2)-1 x 10(-6) M for the 2 drugs over the pH range 5-8 revealed the performance characteristics of these electrodes, which were evaluated according to International Union of Pure and Applied Chemistry recommendations. The method was applied to FX and OX in their pharmaceutical formulations and in human plasma samples. The 4 proposed sensors were found to be specific for the drugs in the presence of up to 60% of their degradation products. Validation of the method according to the quality assurance standards showed suitability of the proposed electrodes for use in the quality control assessment of these drugs. The recoveries for determination of the drugs by the 4 proposed selective electrodes were 99.5 +/- 0.5, 100.0 +/- 0.4, 99.9 +/- 0.4, and 100.1 +/- 0.4% for sensors 1-4, respectively. Statistical comparison between the results obtained by this method and the official method of the drugs was done, and no significant difference found.

  8. Mass spectrometric researches in isotope cosmochemistry

    International Nuclear Information System (INIS)

    Gopalan, K.

    1979-01-01

    Recent advances in the understanding of solar system processes, past and present, based on mass spectrometric researches on meteorites and moon samples are reviewed. The topics include the following : (1) Duration of nebular condensation, (2) Terminal stages of nucleosynthesis, (3) Planetary formation and evolution, (4) Heterogeneities in the solar nebula and (5) Solar wind composition. (auth.)

  9. Analysis of mathematical modelling on potentiometric biosensors.

    Science.gov (United States)

    Mehala, N; Rajendran, L

    2014-01-01

    A mathematical model of potentiometric enzyme electrodes for a nonsteady condition has been developed. The model is based on the system of two coupled nonlinear time-dependent reaction diffusion equations for Michaelis-Menten formalism that describes the concentrations of substrate and product within the enzymatic layer. Analytical expressions for the concentration of substrate and product and the corresponding flux response have been derived for all values of parameters using the new homotopy perturbation method. Furthermore, the complex inversion formula is employed in this work to solve the boundary value problem. The analytical solutions obtained allow a full description of the response curves for only two kinetic parameters (unsaturation/saturation parameter and reaction/diffusion parameter). Theoretical descriptions are given for the two limiting cases (zero and first order kinetics) and relatively simple approaches for general cases are presented. All the analytical results are compared with simulation results using Scilab/Matlab program. The numerical results agree with the appropriate theories.

  10. Spectrometric techniques 2

    CERN Document Server

    Vanasse, George A

    2013-01-01

    Spectrometric Techniques, Volume II provides information pertinent to vacuum ultraviolet techniques to complete the demonstration of the diversity of methods available to the spectroscopist interested in the ultraviolet visible and infrared spectral regions. This book discusses the specific aspects of the technique of Fourier transform spectroscopy.Organized into five chapters, this volume begins with an overview of the large number of systematic effects in the recording of an interferogram. This text then examines the design approach for a Fourier transform spectrometer with focus on optics.

  11. Microprocessor-controlled system for automatic acquisition of potentiometric data and their non-linear least-squares fit in equilibrium studies.

    Science.gov (United States)

    Gampp, H; Maeder, M; Zuberbühler, A D; Kaden, T A

    1980-06-01

    A microprocessor-controlled potentiometric titration apparatus for equilibrium studies is described. The microprocessor controls the stepwise addition of reagent, monitors the pH until it becomes constant and stores the constant value. The data are recorded on magnetic tape by a cassette recorder with an RS232 input-output interface. A non-linear least-squares program based on Marquardt's modification of the Newton-Gauss method is discussed and its performance in the calculation of equilibrium constants is exemplified. An HP 9821 desk-top computer accepts the data from the magnetic tape recorder. In addition to a fully automatic fitting procedure, the program allows manual adjustment of the parameters. Three examples are discussed with regard to performance and reproducibility.

  12. ALPHA SPECTROMETRIC EVALUATION OF SRM-995 AS A POTENTIAL URANIUM/THORIUM DOUBLE TRACER SYSTEM FOR AGE-DATING URANIUM MATERIALS

    Energy Technology Data Exchange (ETDEWEB)

    Beals, D.

    2011-12-06

    Uranium-233 (t{sub 1/2} {approx} 1.59E5 years) is an artificial, fissile isotope of uranium that has significant importance in nuclear forensics. The isotope provides a unique signature in determining the origin and provenance of uranium-bearing materials and is valuable as a mass spectrometric tracer. Alpha spectrometry was employed in the critical evaluation of a {sup 233}U standard reference material (SRM-995) as a dual tracer system based on the in-growth of {sup 229}Th (t{sub 1/2} {approx} 7.34E3 years) for {approx}35 years following radiochemical purification. Preliminary investigations focused on the isotopic analysis of standards and unmodified fractions of SRM-995; all samples were separated and purified using a multi-column anion-exchange scheme. The {sup 229}Th/{sup 233}U atom ratio for SRM-995 was found to be 1.598E-4 ({+-} 4.50%) using recovery-corrected radiochemical methods. Using the Bateman equations and relevant half-lives, this ratio reflects a material that was purified {approx} 36.8 years prior to this analysis. The calculated age is discussed in contrast with both the date of certification and the recorded date of last purification.

  13. The leakage problem in vacuum system. Realization of a mass spectrometer detecting leaks; Le probleme des fuites en technique du vide. Realisation d'un spectrometre de masse detecteur de fuite

    Energy Technology Data Exchange (ETDEWEB)

    Geller, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1954-11-15

    In the first part of this paper we consider the problem of leaks in vacuum systems, and their detection. We consider in particular the method of detection by means of a helium spectrometer. The second part deals with the experimental set p. The analyser and the ion source have been studied in great detail, and we have also discussed the technological and mechanical aspects of the apparatus and its performances. (author) [French] Dans la premiere partie de ce travail, nous traitons le probleme des fuites en technique du vide et leur detection en general. La methode de detection par spectrometre a helium y est envisagee plus particulierement. La deuxieme partie de l'article est consacree a la realisation du spectrometre. Le tube analyseur et la source d'ions y sont etudies en detail. Nous exposons de meme les conceptions technologiques et mecaniques de l'appareil ainsi que ses performances. (auteur)

  14. Dysprosium selective potentiometric membrane sensor

    Energy Technology Data Exchange (ETDEWEB)

    Zamani, Hassan Ali, E-mail: haszamani@yahoo.com [Department of Applied Chemistry, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of); Faridbod, Farnoush; Ganjali, Mohammad Reza [Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of)

    2013-03-01

    A novel Dy(III) ion-selective PVC membrane sensor was made using a new synthesized organic compound, 3,4-diamino-N Prime -((pyridin-2-yl)methylene)benzohydrazide (L) as an excellent sensing element. The electrode showed a Nernstian slope of 19.8 {+-} 0.6 mV per decade in a wide concentration range of 1.0 Multiplication-Sign 10{sup -6}-1.0 Multiplication-Sign 10{sup -2} mol L{sup -1}, a detection limit of 5.5 Multiplication-Sign 10{sup -7} mol L{sup -1}, a short conditioning time, a fast response time (< 10 s), and high selectivity towards Dy(III) ion in contrast to other cations. The proposed sensor was successfully used as an indicator electrode in the potentiometric titration of Dy(III) ions with EDTA. The membrane sensor was also applied to the F{sup -} ion indirect determination of some mouth washing solutions and to the Dy{sup 3+} determination in binary mixtures. Highlights: Black-Right-Pointing-Pointer The novelty of this work is based on the high affinity of the ionophore toward the Dy{sup 3+} ions. Black-Right-Pointing-Pointer This technique is very simple, fast and inexpensive and it is not necessary to use sophisticated equipment. Black-Right-Pointing-Pointer The newly developed sensor is superior to the formerly reported Dy{sup 3+} sensors in terms of selectivity.

  15. Modern Directions for Potentiometric Sensors

    Science.gov (United States)

    Bakker, Eric; Chumbimuni-Torres, Karin

    2009-01-01

    This paper gives an overview of the newest developments of polymeric membrane ion-selective electrodes. A short essence of the underlying theory is given, emphasizing how the electromotive force may be used to assess binding constants of the ionophore, and how the selectivity and detection limit are related to the underlying membrane processes. The recent developments in lowering the detection limits of ISEs are described, including recent approaches of developing all solid state ISEs, and breakthroughs in detecting ultra-small quantities of ions at low concentrations. These developments have paved the way to use potentiometric sensors as in ultra-sensitive affinity bioanalysis in conjunction with nanoparticle labels. Recent results establish that potentiometry compares favorably to electrochemical stripping analysis. Other new developments with ion-selective electrodes are also described, including the concept of backside calibration potentiometry, controlled current coulometry, pulsed chronopotentiometry, and localized flash titration with ion-selective membranes to design sensors for the direct detection of total acidity without net sample perturbation. These developments have further opened the field for exciting new possibilities and applications. PMID:19890473

  16. Regional potentiometric-surface map of the Great Basin carbonate and alluvial aquifer system in Snake Valley and surrounding areas, Juab, Millard, and Beaver Counties, Utah, and White Pine and Lincoln Counties, Nevada

    Science.gov (United States)

    Gardner, Philip M.; Masbruch, Melissa D.; Plume, Russell W.; Buto, Susan G.

    2011-01-01

    Water-level measurements from 190 wells were used to develop a potentiometric-surface map of the east-central portion of the regional Great Basin carbonate and alluvial aquifer system in and around Snake Valley, eastern Nevada and western Utah. The map area covers approximately 9,000 square miles in Juab, Millard, and Beaver Counties, Utah, and White Pine and Lincoln Counties, Nevada. Recent (2007-2010) drilling by the Utah Geological Survey and U.S. Geological Survey has provided new data for areas where water-level measurements were previously unavailable. New water-level data were used to refine mapping of the pathways of intrabasin and interbasin groundwater flow. At 20 of these locations, nested observation wells provide vertical hydraulic gradient data and information related to the degree of connection between basin-fill aquifers and consolidated-rock aquifers. Multiple-year water-level hydrographs are also presented for 32 wells to illustrate the aquifer system's response to interannual climate variations and well withdrawals.

  17. Highly sensitive covalently functionalized light-addressable potentiometric sensor for determination of biomarker

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Jintao [School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Guangxi Experiment Center of Information Sciences, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Guan, Mingyuan; Huang, Guoyin; Qiu, Hengming; Chen, Zhengcheng [School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Li, Guiyin, E-mail: liguiyin01@163.com [School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Guangxi Experiment Center of Information Sciences, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Huang, Yong, E-mail: huangyong503@126.com [School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Guangxi Experiment Center of Information Sciences, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China)

    2016-06-01

    A biomarker is related to the biological status of a living organism and shows great promise for the early prediction of a related disease. Herein we presented a novel structured light-addressable potentiometric sensor (LAPS) for the determination of a model biomarker, human immunoglobulin G (hIgG). In this system, the goat anti-human immunoglobulin G antibody was used as recognition element and covalently immobilized on the surface of light-addressable potentiometric sensor chip to capture human immunoglobulin G. Due to the light addressable capability of light-addressable potentiometric sensor, human immunoglobulin G dissolved in the supporting electrolyte solution can be detected by monitoring the potential shifts of the sensor. In order to produce a stable photocurrent, the laser diode controlled by field-programmable gate array was used as the light emitter to drive the light-addressable potentiometric sensor. A linear correlation between the potential shift response and the concentration of human immunoglobulin G was achieved and the corresponding regression equation was ΔV (V) = 0.00714C{sub hIgG} (μg/mL)–0.0147 with a correlation coefficient of 0.9968 over a range 0–150 μg/mL. Moreover, the light-addressable potentiometric sensor system also showed acceptable stability and reproducibility. All the results demonstrated that the system was more applicable to detection of disease biomarkers with simple operation, multiple-sample format and might hold great promise in various environmental, food, and clinical applications. - Highlights: • A novel structured light-addressable potentiometric sensor (LAPS) based on covalently functionalized membrane was designed. • The composition of the surface of LAPS chip was investigated by X-ray photoelectron spectroscopy (XPS). • hIgG dissolved in the supporting electrolyte solution can be detected by monitoring the potential shifts of LAPS.

  18. Potentiometric determination of iodides in urine

    International Nuclear Information System (INIS)

    Gikolaev, B.A.; Primakova, L.N.; Rakhman'ko, E.M.

    1996-01-01

    Variants of potentiometric method: determination using a calibrations plot, the Gran method, and the double addition method are considered. The method of double additions of the test solution to the reference one is suggested as the most favorable method of determining iodides in urine under clinical laboratory conditions. Refs. 5, tabs. 2

  19. New medical imaging systems exploiting the energy dispersive X-ray diffraction with spectrometric CdZnTe based detector

    International Nuclear Information System (INIS)

    Barbes, Damien

    2016-01-01

    This thesis studies the interest of measuring the coherent scattering of X-rays for breast diagnosis imaging. Nowadays, most of X-ray-based medical imaging techniques use the information of X-rays attenuation through the tissues. It is the case for mammography, the most common breast imaging modality. The recent emergence of energy resolved detectors (based on semiconductors in particular) allows to consider using another phenomenon: the coherent X-ray scattering. Measurement of diffracted spectra can provide new information related to the molecular structure of the examined tissues, in order to improve their characterization and therefore improve the final diagnosis. Two modalities are considered: the breast cancer detection in vivo, following a suspicious mammography result, or biopsy analysis. The coherent scattering measurement system developed during this thesis work uses energy-resolved CdZnTe-based detectors, these detectors combining performances (energy resolution, sensitivity, spatial resolution, and compactness) promising for clinical application. This system is also based on the detector pixelation, which allows to provide an imaging modality capable of characterizing analyzed materials or tissues in one direction without any translation or rotation. A complete study of the measurement system is proposed in this thesis, structured in three main parts: modeling and simulation of the system, development of the processing of the data measured by the detector in order to image and characterize the analyzed sample and finally, designing of a new and more complex experimental setup based on a whole detector and multi-slit collimation system. An experimental validation is proposed for each of these three parts. (author) [fr

  20. Development of a portable mass spectrometric system for determination of isotopic composition of solid uranium samples using fluorine volatilization

    Science.gov (United States)

    Loge, G.

    1994-09-01

    Using hardware and materials supplied by LANL, a prototype quadrupole mass spectrometer system designed for portable field analysis of isotopic composition of solid uranium samples was assembled and tested. The system contained the capability for fluorine volatilization of solid uranium samples with gas introduction, which was successfully tested and demonstrated using 100 mg samples of U3O8. Determination of precision and accuracy for measuring isotopic composition was performed using isotopic standards. Use with soil samples containing uranium were also attempted. Silicates in the soil forming SiF4 were found to be a kinetic bottleneck to the formation of UF6. This could be avoided by performing some sort of chemical separation as a pre-treatment step, which was demonstrated using nitric acid.

  1. NZG 201 portable spectrometric unit

    International Nuclear Information System (INIS)

    Jursa, P.; Novakova, O.; Slezak, V.

    The NZG 201 spectrometric unit is a portable single-channel processing unit supplied from the mains or a battery which allows the qualitative and quantitative measurement of different types of ionizing radiation when connected to a suitable detection unit. The circuit layout and the choice of control elements makes the spectrometric unit suitable for use with scintillation detector units. The spectrometric unit consists of a pulse amplifier, an amplitude pulse analyzer, a pulse counter, a pulse rate counter with an output for a recorder, a high voltage source and a low voltage source. The block diagram is given. All circuits are modular and are mounted on PCB's. The apparatus is built in a steel cabinet with a raised edge which protects the control elements. The linear pulse amplifier has a maximum gain of 1024, the pulse counter has a maximum capacity of 10 6 -1 imp and time resolution better than 0.5 μs. The temperature interval at which the apparatus is operational is 0 to 45 degC, its weight is 12.5 kg and dimensions 36x280x310 mm, energy range O.025 to 2.5 MeV, for 137 Cs the energy resolution is 8 to 10%. The spectrometric unit NZG 2O1 may, with regard to its parameters, number and range of control elements, be used as a universal measuring unit. (J.P.)

  2. Comparison of the precision and accuracy of digital versus analogue gamma-ray spectrometric systems used in INAA for evaluation of homogeneity and certification of reference materials of the IAEA

    International Nuclear Information System (INIS)

    Makarewicz, M.; Burns, K.

    2000-01-01

    Performance of three commercial gamma-ray spectrometric systems was evaluated for precision and accuracy prior to use in characterization of reference materials. Two of the systems were based on fast processing of the analogue signal from the amplifier (EGG Ortec model 672) using a loss free counting module (Canberra model LFC 599) interfaced to one of two analog-to-digital converters (Canberra models 8713 or 8715). The third system was based on a digital signal processor (Canberra model DSP 9660). Performance of the systems was tested over a range of count rates up to a maximum of 70,000 counts per second (dead time up to 90%) using 60 Co and 137 Cs sources. Best resolution was achieved with an analogue system with ADC 8713. The analytical results obtained with the digital system show the lowest and well-quantified uncertainty. (author)

  3. Potentiometric perchlorate determination at nanomolar concentrations in vegetables.

    Science.gov (United States)

    Leoterio, Dilmo M S; Paim, Ana Paula S; Belian, Mônica F; Galembeck, André; Lavorante, André F; Pinto, Edgar; Amorim, Célia G; Araújo, Alberto N; Montenegro, Maria C B S M

    2017-07-15

    In this work, an expeditious method based on the multi-commutated flow-analysis concept with potentiometric detection is proposed to perform determinations of the emergent contaminant perchlorate in vegetable matrices down to nanomolar concentration. To accomplish the task, a tubular shaped potentiometric sensor selective to perchlorate ion was constructed with a PVC membrane containing 12mmol/kg of the polyamine bisnaphthalimidopropyl-4,4'-diaminodiphenylmethane and 2-nitrophenyl phenyl ether 68% (w/w) as plasticizer casted on a conductive epoxy resin. Under optimal flow conditions, the sensor responded linearly in the concentration range of 6.3×10 -7 -1.0×10 -3 mol/L perchlorate. In order to extend the determinations to lower concentrations (4.6(±1.3)×10 -10 mol/L perchlorate), a column packed with 70mg of sodium 2,5,8,11,14-pentaoxa-1-silacyclotetradecane-polymer was coupled to the flow-system thus enabling prior pre-concentration of the perchlorate. The proposed procedure provides a simpler alternative for the determination of perchlorate in foods, nowadays only allowed by sophisticated and expensive equipment and laborious methods. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. A computer controlled potentiometric titrator for quantitative determination of uranium

    International Nuclear Information System (INIS)

    Verdingh, V.; Michiels, A.

    1988-01-01

    The modified Davies and Gray methods is frequently used for the potentiometric titration of uranium. It is based upon the reduction of U(VI) to U(IV) with a reductant (e.g. Fe ++ ) followed by a selective oxidation of the excess of reductant and subsequent titration of U(IV) with potassium dichromate (K 2 Cr 2 O 7 ). Interference from other elements is low, but the method is rather cumbersome due to the number of reactants to be added before the titration is started. The timing of these additions also plays a role. In order to render the titration less dependent on human factors and with the aim of reaching high reproducibility, a computer controlled system has been designed and set-up. Reagents are added by five computer controlled burettes. A program allows the choice of volumes and waiting times, and commands the start of the final titration which is followed by the microprocessor of the automatic potentiometric titrator. In this way a routine uranium titration can be completed in about twelve minutes. Reproducibilities of the order of ±15% are achievable in routine operation. For high precision work, the titrator is used as an end-point detector. Titrant is added manually by mass, so as to react with > 99% of the uranium. The residual uranium is then titrated automatically by colume with diluted titrant. The precision can be improved by a factor of approximately ten. (orig.)

  5. Potentiometric titration of metal ions in ethanol.

    Science.gov (United States)

    Gibson, Graham T T; Mohamed, Mark F; Neverov, Alexei A; Brown, R S

    2006-09-18

    The potentiometric titrations of Zn2+, Cu2+ and 12 Ln3+ metal ions were obtained in ethanol to determine the titration constants (defined as the at which the [-OEt]/[Mx+]t ratios are 0.5, 1.5, and 2.5) and in two cases (La3+ and Zn2+) a complete speciation diagram. Several simple monobasic acids and aminium ions were also titrated to test the validity of experimental titration measurements and to establish new constants in this medium that will be useful for the preparation of buffers and standard solutions. The dependence of the titration constants on the concentration and type of metal ion and specific counterion effects is discussed. In selected cases, the titration profiles were analyzed using a commercially available fitting program to obtain information about the species present in solution, including La3+ for which a dimer model is proposed. The fitting provides the microscopic values for deprotonation of one to four metal-bound ethanol molecules. Kinetics for the La3+-catalyzed ethanolysis of paraoxon as a function of are presented and analyzed in terms of La3+ speciation as determined by the analysis of potentiometric titration curves. The stability constants for the formation of Zn2+ and Cu2+ complexes with 1,5,9-triazacyclododecane as determined by potentiometric titration are presented.

  6. Changes in the potentiometric-surface altitude of the confined aquifer, Wood River Valley aquifer system, south-central Idaho, October 2006 to October 2012.

    Data.gov (United States)

    Department of the Interior — Water levels in 93 wells completed in the Wood River Valley aquifer system were measured during October 22–24, 2012; these wells are part of a network established...

  7. Potentiometric and amperometric titration of ferrocene by cerium(4)

    International Nuclear Information System (INIS)

    Solomatin, V.T.

    1985-01-01

    Redox-potentials (E) of ferrocene (ferricenium-cation), Ce(4)/Ce(3) pairs are investigated and a possibility of regulating E value of these systems depending on the composition of water-organic media is shown. E value of Ce(4)/Ce(3) system decreases as increasing H 2 SO 4 concentration and CH 3 COOH mol share in the water-organic phase. Kinetic investigations of Ce(4)-ferrocene reactions shown that E constant value is achieved in 12-16 s depending on donor-acceptor properties of the solvent. Optimum conditions are chosen for potentiometric and amperometric titration of ferrocene by ceruium (4) in technological products. The method is versatile and permits to determine from tenths to dozens per cent of ferrocene

  8. Determination of vanadium(V) by direct automatic potentiometric titration with EDTA using a chemically modified electrode as a potentiometric sensor.

    Science.gov (United States)

    Quintar, S E; Santagata, J P; Cortinez, V A

    2005-10-15

    A chemically modified electrode (CME) was prepared and studied as a potentiometric sensor for the end-point detection in the automatic titration of vanadium(V) with EDTA. The CME was constructed with a paste prepared by mixing spectral-grade graphite powder, Nujol oil and N-2-naphthoyl-N-p-tolylhydroxamic acid (NTHA). Buffer systems, pH effects and the concentration range were studied. Interference ions were separated by applying a liquid-liquid extraction procedure. The CME did not require any special conditioning before using. The electrode was constructed with very inexpensive materials and was easily made. It could be continuously used, at least two months without removing the paste. Automatic potentiometric titration curves were obtained for V(V) within 5 x 10(-5) to 2 x 10(-3)M with acceptable accuracy and precision. The developed method was applied to V(V) determination in alloys for hip prosthesis.

  9. Potentiometric assay for hydrogenocarbonate in natural waters

    OpenAIRE

    Milla González, Miguel

    2008-01-01

    Potentiometry is often used for the determination of hydrogenocarbonate in natural water samples. In this exercise, a volume V of the titrant HCl is required for the potentiometric analysis of the mentioned species in 50 mL of water sample. The titrant concentration is M molar. The user should calculate the concentration of hydrogenocarbonate and express it either in mg/L or in g/L of calcium carbonate by building up the corresponding stoichiometric expressions. All results entered in the sys...

  10. Application of a field flow preconcentration system with a minicolumn packed with amberlite XAD-4/1-(2-pyridylazo)-2-naphtol and a flow injection-flame atomic adsorption spectrometric system for lead determination in sea water

    International Nuclear Information System (INIS)

    Carmen Yebra, M. del; Rodriguez, L.; Puig, L.; Moreno-Cid, A.

    2002-01-01

    A field flow preconcentration technique involving a minicolumn containing Amberlite XAD-4 impregnated with the complexing agent 1-(2-pyridylazo)-2-naphthol was used to preconcentrate lead from seawater. Elution of retained lead on the minicolumns was performed by a flow-injection-flame atomic absorption spectrometric system. Factorial designs have been used to optimize the field flow preconcentration system and the flow injection elution process. Factors such as sample pH, sample flow-rate, eluent concentration and volume (hydrochloric acid), elution flow-rate and minicolumn diameter were considered. The results suggest that the sample flow-rate and the eluent volume are statistically significant factors. The detection limit (3σ) of the procedure was 5 ng/L for a sample volume of 1000 ml. The precision (expressed as relative standard deviation) for eleven independent determinations reached values of 4.0-3.1 % in lead solutions of 50-200 ng/L. This procedure has been successfully applied to the determination of lead in seawater from Galicia (Spain). (author)

  11. Hydrogeology, groundwater levels, and generalized potentiometric-surface map of the Green River Basin lower Tertiary aquifer system, 2010–14, in the northern Green River structural basin

    Science.gov (United States)

    Bartos, Timothy T.; Hallberg, Laura L.; Eddy-Miller, Cheryl

    2015-07-14

    In cooperation with the Bureau of Land Management, groundwater levels in wells located in the northern Green River Basin in Wyoming, an area of ongoing energy development, were measured by the U.S. Geological Survey from 2010 to 2014. The wells were completed in the uppermost aquifers of the Green River Basin lower Tertiary aquifer system, which is a complex regional aquifer system that provides water to most wells in the area. Except for near perennial streams, groundwater-level altitudes in most aquifers generally decreased with increasing depth, indicating a general downward potential for groundwater movement in the study area. Drilled depth of the wells was observed as a useful indicator of depth to groundwater such that deeper wells typically had a greater depth to groundwater. Comparison of a subset of wells included in this study that had historical groundwater levels that were measured during the 1960s and 1970s and again between 2012 and 2014 indicated that, overall, most of the wells showed a net decline in groundwater levels.

  12. Scanning electrochemical microscopy determination of hydrogen flux at liquid|liquid interface with potentiometric probe

    OpenAIRE

    Jedraszko, Justyna; Nogala, Wojciech; Adamiak, Wojciech; Girault, Hubert H.; Opallo, Marcin

    2014-01-01

    Scanning electrochemical microscopy potentiometric determination of local hydrogen concentration and its flux next to the liquid|liquid interface was demonstrated. This method is based on the shift of open circuit potential of Pt-based reversible hydrogen electrode. The detection system was verified with a system generating hydrogen under galvanostatic conditions. Then, it was applied to aqueous|1,2-dichloroethane interface where hydrogen is produced with decamethylferrocene as electron donor.

  13. Implementation of the automated potentiometric titration method for total U at the CNEN Safeguard Laboratory, Brazil

    International Nuclear Information System (INIS)

    Cristiano, Barbara F.G.; Delgado, Jose U.; Araujo, Radier M.S. de; Silva, Jose W.S. da; Barros, Pedro D. de

    2009-01-01

    Brazilian nuclear facilities, in accordance with the regulation CNEN-NN-2.02, must have available measurement systems which allow to determine their nuclear material inventories. For the evaluation and the follow up the performance of the involved laboratories in those measurement systems, the accomplishment of interlaboratory comparison programmes becomes fundamental. Therefore, the implementation of the potentiometric titration viewing the characterization of uranium samples, represents an reference element for the Brazilian programs

  14. Spectrometric assembly for portable installations

    International Nuclear Information System (INIS)

    Kluger, A.; Popescu, C.

    1997-01-01

    The components of the portable spectrometric assembly are: - the detecting probe with Na I(Tl) crystal and air-tight case of industrial type; - a microcomputer; - a unit of analogical processing of the signal from the detecting probe; - a single-channel analyzer with adjustable threshold; - commands and display module; - a source of high voltage; - an electrical supply battery. The device uses the method of gamma photons detection in energetic windows. Through theoretical and experimental studies carried out during the prototype development phase, the superiority of this method has been proved as compared with the installations which make use of the classical principle of photon integral detection. The achieved prototype has a basic program enabling the setting of all working parameters (measuring time, discriminating thresholds, discriminators operating conditions, etc.). Through the included interface RS232 it is possible to transmit the data to a more powerful computer in order to continually process the results. The spectrometric assembly, realized on the basis of micro-computers, can be used in a wide range of applications: measurement of thickness and erosion of walls and tubes, measurement of level in closed containers, of soil density, etc. The adjustment for specific application is performed only through a program modification. (authors)

  15. Revised potentiometric-surface map, Yucca Mountain and vicinity, Nevada

    International Nuclear Information System (INIS)

    Ervin, E.M.; Luckey, R.R.; Burkhardt, D.J.

    1994-01-01

    The revised potentiometric-surface map presented in this report updates earlier maps of the Yucca Mountain area using mainly 1988 average water levels. Because of refinements in the corrections to the water-level measurements, these water levels have increased accuracy and precision over older values. The small-gradient area to the southeast of Yucca Mountain is contoured with a 0.25-meter interval and ranges in water-level altitude from 728.5 to 73 1.0 meters. Other areas with different water levels, to the north and west of Yucca Mountain, are illustrated with shaded patterns. The potentiometric surface can be divided into three regions: (1) A small-gradient area to the southeast of Yucca Mountain, which may be explained by flow through high-transmissivity rocks or low ground-water flux through the area; (2) A moderate-gradient area, on the western side of Yucca Mountain, where the water-level altitude ranges from 775 to 780 meters, and appears to be impeded by the Solitario Canyon Fault and a splay of that fault; and (3) A large-gradient area, to the north-northeast of Yucca Mountain, where water level altitude ranges from 738 to 1,035 meters, possibly as a result of a semi-perched groundwater system. Water levels from wells at Yucca Mountain were examined for yearly trends using linear least-squares regression. Data from five wells exhibited trends which were statistically significant, but some of those may be a result of slow equilibration of the water level from drilling in less permeable rocks. Adjustments for temperature and density changes in the deep wells with long fluid columns were attempted, but some of the adjusted data did not fit the surrounding data and, thus, were not used

  16. Structures, equilibria and ligand exchange dynamics in the binary and ternary dioxouranium(VI)-ethylenediamine-N-N'-diacetic acid - fluoride system; a potentiometric, NMR and X-ray study

    International Nuclear Information System (INIS)

    Palladino, G.; Szabo, Z.; Fischer, A.; Grenthe, I.

    2005-01-01

    Full text of publication follows: The structure, thermodynamics and kinetics of the binary and ternary Uranyl(VI)- ethylenediamine- N-N'-di-acetate (in the following denoted EDDA) fluoride system have been studied using potentiometry, 1 H, 19 F NMR and a single-crystal X-ray determination. The potentiometric data were obtained using measurements of the free hydrogen ion and fluoride concentrations with glass and fluoride electrodes, respectively. The experimental data were used to deduce stoichiometry and equilibrium constants using a least square refinements programme. The UO 2 2+ - EDDA system could be studied up to -log[H 3 O + ] 3.4, after which a precipitate was formed. The test solutions contained two binary complexes, the uncharged UO 2 (EDDA)(aq) and UO 2 (H 3 EDDA) 3+ , with equilibrium constants log β(UO 2 EDDA) = 11.63 ± 0.02 and log β(UO 2 H 3 EDDA 3+ ) = 1.77 ± 0.04, respectively. By using fluoride as additional ligand the solubility increases because of the formation of very stable ternary complexes that allowed an experimental study over a larger pH range. The structure of the complexes in the ternary system was deduced using a combination of 1 H and 19 F NMR spectroscopy. The 19 F NMR spectra at lower pH, had peaks from the binary fluoride complexes (UO 2 F + , UO 2 F 2 (aq) and UO 2 F 3 - ) that could be used to obtain information on the equilibrium constants in the ternary system; at -log[H 3 O + ] > 4.7 new signals for the complexes (UO 2 ) 2 (EDDA) 2 F 2 2- , and UO 2 (EDDA)F - were observed. The analyses of 1 H NMR spectra indicate clearly that the EDDA ligand is chelate bonded in UO 2 (EDDA)F-. The fluorine exchange between UO 2 (EDDA)F- and UO 2 F 3 - was studied using 19 F NMR line-broadening technique. The experimental rate constant is k obs = k 0 + k 1 [UO 2 F 3 - ], with k 0 (3.24 ± 0.06) 10 2 s -1 and k 1 = (71.2 ± 2.3) 10 3 M -1 s -1 .The rate and the activation parameters for the exchange between UO 2 (EDDA)F - complex and free

  17. The Potentiometric Titration of Filtrates from the Bachmann Process

    Science.gov (United States)

    1942-06-23

    SCIENTIFIC RESEARCH AND DEVELOP11ENT The Potentiometric Titration of Filtrates from the Bachmann Process (OD-12) by F. C. Whitmore OSRD No. 654... Potentiometric Titration of Synthetic Mixtures. A? Nitric Acid-Acetic Acid. A sample of 60 ml. glacial acetic acid war diluted to 200 ml. with distilled...i4flinflr?fj3 TADLE 1 CO) |S?lDBnTl» POTENTIOMETRIC TITRATION OF SYNTHETIC t’.IXTURES WITH CONCENTRATED AJKDNIUM HYDROXIDE A; unonium HNO-j- AcOfi Ky

  18. Potentiometric determination of the tungsten content of tantalum-tungsten alloys with chromium II

    International Nuclear Information System (INIS)

    Gavra, Z.; Ronen, S.; Levin, R.

    1977-05-01

    A method was developed for the potentiometric determination of the tungsten content of tantalum-tungsten alloys of different compositions. These were dissolved under conditions that enabled the tungsten content to be determined with chromium (II). Phosphoric acid was selected as a suitable complexing agent for the prevention of the precipitation of tungsten and tantalum compounds. The use of chromium (II) required an oxygen-tight system and therefore the work was carried out in suitable vessels for storage and tritation

  19. Mass spectrometric detection of radiocarbon for dating applications

    OpenAIRE

    Synal Hans-Arno

    2013-01-01

    Radiocarbon is still the most important nuclide measured by accelerator mass spectrometry (AMS). The related capabilities for dating and tracer studies are eminent not only in archaeology but also drive important applications in the earth and environmental sciences as well as in biomedical research. So far standard mass spectrometric systems have not been capable of radiocarbon dating because of interfering molecular isobars which however can be completely eliminated in charge changing proces...

  20. Potentiometric Measurement of Transition Ranges and Titration Errors for Acid/Base Indicators

    Science.gov (United States)

    Flowers, Paul A.

    1997-07-01

    Sophomore analytical chemistry courses typically devote a substantial amount of lecture time to acid/base equilibrium theory, and usually include at least one laboratory project employing potentiometric titrations. In an effort to provide students a laboratory experience that more directly supports their classroom discussions on this important topic, an experiment involving potentiometric measurement of transition ranges and titration errors for common acid/base indicators has been developed. The pH and visually-assessed color of a millimolar strong acid/base system are monitored as a function of added titrant volume, and the resultant data plotted to permit determination of the indicator's transition range and associated titration error. Student response is typically quite positive, and the measured quantities correlate reasonably well to literature values.

  1. Potentiometric titration curves of aluminium salt solutions and its ...

    African Journals Online (AJOL)

    Potentiometric titration curves of aluminium salt solutions and its species conversion ... of aluminium salt solutions under the moderate slow rate of base injection. ... silicate radical, and organic acid radical on the titration curves and its critical ...

  2. Potentiometric studies on quaternary complexes of dioxouranium(VI)

    Energy Technology Data Exchange (ETDEWEB)

    Kumari, Vinod; Chaturvedi, G K [Agra Coll., (India). Chemical Laboratories

    1979-10-01

    The formation of quaternary complexes of dioxouranium(VI) with three different organic acids (OX, MALN and SA, SSA, TAR or TMA) has been inferred from the potentiometric studies. The formation constants for the resulting triligand complexes have been evaluated.

  3. Potentiometric Titration Method for Quantitative Determination of Hydrogen Peroxide

    National Research Council Canada - National Science Library

    Bessette, Russell R

    2005-01-01

    An electrochemical potentiometric titration method that entails titration of a known volume of a catholyte containing an unknown amount of hydrogen peroxide in a titration cell having two electrodes...

  4. Electrolyte system strategies for anionic isotachophoresis with electrospray-ionization mass-spectrometric detection. 2. Isotachophoresis in moving-boundary systems

    Czech Academy of Sciences Publication Activity Database

    Gebauer, Petr; Malá, Zdeňka; Boček, Petr

    2013-01-01

    Roč. 34, č. 24 (2013), s. 3245-3251 ISSN 0173-0835 R&D Project s: GA ČR(CZ) GA13-05762S Institutional support: RVO:68081715 Keywords : electrolyte systems * ESI-MS detection * isotachophoresis * moving-boundary electrophoresis Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.161, year: 2013

  5. Potentiometric studies on the complexes of tetracycline (TC) and oxytetracycline (OTC) with some metal ions

    International Nuclear Information System (INIS)

    Ghandour, M.A.; Azab, H.A.; Hassan, A.; Ali, A.M.

    1992-01-01

    The interaction of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Zn(II), Cd(II), Hg(II), Pb(II), Al(III), and UO 2 (II) ions with tetracycline (TC) were studied by potentiometric pH titrations. The formation constants of the different binary complexes formed in such systems have been determined at 25±0.1 deg C and μ=0.1 moll -1 (NaNO 3 ). Potentiometric pH equilibrium measurements have been made under the same conditions for the interaction of oxytetracycline (OTC) and Cu(II), Cd(II), Pb(II), and UO 2 (II). The formation of (1:1) binary complexes are inferred from the potentiometric pH titration curves. The protonation constants of TC and OTC were also determined under the same conditions and refined (ESAB2M computer program). The transition metal stability constants are consistent with the Irving-Williams series. (authors)

  6. Potentiometric Surface of the Upper Floridan Aquifer, West-Central Florida, September 2006

    Science.gov (United States)

    Ortiz, A.G.

    2007-01-01

    The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing freshwater are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is the principal source of water in the Southwest Florida Water Management District and is used for major public supply, domestic use, irrigation, and brackish water desalination in coastal communities (Southwest Florida Water Management District, 2000). This map report shows the potentiometric surface of the Upper Floridan aquifer measured in September 2006. The potentiometric surface is an imaginary surface connecting points of equal altitude to which water will rise in tightly cased wells that tap a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the wet season, when ground-water levels usually are at an annual high and withdrawals for agricultural use typically are low. The cumulative average rainfall of 46.06 inches for west-central Florida (from October 2005 through September 2006) was 6.91 inches below the historical cumulative average of 52.97 inches (Southwest Florida Water Management District, 2006). Historical cumulative averages are calculated from regional rainfall summary reports (1915 to most recent complete calendar year) and are updated monthly by the Southwest Florida Water Management District. This report, prepared by the U.S. Geological Survey in cooperation with the Southwest Florida Water Management District, is part of a semi-annual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September since 1975. Water-level data are collected in May and September each

  7. Potentiometric Surface of the Upper Floridan Aquifer, West-Central Florida, September 2007

    Science.gov (United States)

    Ortiz, A.G.

    2008-01-01

    The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing fresh water are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is the principal source of water in the Southwest Florida Water Management District and is used for major public supply, domestic use, irrigation, and brackish water desalination in coastal communities (Southwest Florida Water Management District, 2000). This map report shows the potentiometric surface of the Upper Floridan aquifer measured in September 2007. The potentiometric surface is an imaginary surface connecting points of equal altitude to which water will rise in tightly-cased wells that tap a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the wet season, when ground-water levels usually are at an annual high and withdrawals for agricultural use typically are low. The cumulative average rainfall of 39.50 inches for west-central Florida (from October 2006 through September 2007) was 13.42 inches below the historical cumulative average of 52.92 inches (Southwest Florida Water Management District, 2007). Historical cumulative averages are calculated from regional rainfall summary reports (1915 to most recent complete calendar year) and are updated monthly by the Southwest Florida Water Management District. This report, prepared by the U.S. Geological Survey in cooperation with the Southwest Florida Water Management District, is part of a semi-annual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September since 1975. Water-level data are collected in May and September each

  8. Potentiometric surface of the Upper Floridan aquifer, west-central Florida, September 2005

    Science.gov (United States)

    Ortiz, A.G.

    2006-01-01

    The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing freshwater are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is the principal source of water in the Southwest Florida Water Management District and is used for major public-supply, domestic use, irrigation, and brackish-water desalination in coastal communities (Southwest Florida Water Management District, 2000).This map report shows the potentiometric surface of the Upper Floridan aquifer measured in September 2005. The potentiometric surface is an imaginary surface, connecting points of equal altitude to which water will rise in tightly cased wells that tap a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the wet season, when ground-water levels usually are at an annual high and withdrawals for agricultural use typically are low. The cumulative average rainfall of 55.19 inches for west-central Florida (from October 2004 through September 2005) was 2.00 inches above the historical cumulative average of 53.19 inches (Southwest Florida Water Management District, 2005). Historical cumulative averages are calculated from regional rainfall summary reports (1915 to most recent complete calendar year) and are updated monthly by the Southwest Florida Water Management District.This report, prepared by the U.S. Geological Survey in cooperation with the Southwest Florida Water Management District, is part of a semi-annual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September since 1975. Water-level data are collected in May and September each year

  9. Potentiometric Surface of the Upper Floridan Aquifer, West-Central Florida, May 2007

    Science.gov (United States)

    Ortiz, A.G.

    2008-01-01

    The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing fresh water are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is the principal source of water in the Southwest Florida Water Management District and is used for major public supply, domestic use, irrigation, and brackish water desalination in coastal communities (Southwest Florida Water Management District, 2000). This map report shows the potentiometric surface of the Upper Floridan aquifer measured in May 2007. The potentiometric surface is an imaginary surface connecting points of equal altitude to which water will rise in tightly-cased wells that tap a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the dry season, when ground-water levels usually are at an annual low and withdrawals for agricultural use typically are high. The cumulative average rainfall of 41.21 inches for west-central Florida (from June 2006 through May 2007) was 11.63 inches below the historical cumulative average of 52.84 inches (Southwest Florida Water Management District, 2007). Historical cumulative averages are calculated from regional rainfall summary reports (1915 to most recent complete calendar year) and are updated monthly by the Southwest Florida Water Management District. This report, prepared by the U.S. Geological Survey in cooperation with the Southwest Florida Water Management District, is part of a semi-annual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September since 1975. Water-level data are collected in May and September each year to show the

  10. Potentiometric Membrane Sensors for Levamisole Determination

    Directory of Open Access Journals (Sweden)

    Natalia Zubenya

    2016-11-01

    Full Text Available The ion pair (IP of levamisole with BiI4-(SbI4- for the levamisole-selective sensor with a PVC membrane containing - ions were developed. Thermal behavior of obtained IP was investigated by differential thermal analysis that would show the thermal stability and the character of the decomposition of the complex. The thermolysis of Lev+BiI4- IP undergoes three stages that fit a theoretical interpretation. the linearity ranges of levamisole sensors function are 7.9 ×10-6 – 1×10-1 (7.9 ×10-5 – 1×10-1 M. The Nernstian slope of                   50.6 – 53.4 mV pC−1 and detection limit of 5.0 × 10−5 – 1.5 × 10−4 M. The working range of pH is 2.8 – 6.0.     The efficiency of the use of electrodes for levamisole content control in pharmaceutical preparations was shown by direct potentiometry and potentiometric titration methods.

  11. Proton conducting ceramics for potentiometric hydrogen sensors for molten metals

    Energy Technology Data Exchange (ETDEWEB)

    Borland, H.; Llivina, L.; Colominas, S.; Abellà, J., E-mail: jordi.abella@iqs.edu

    2013-10-15

    Highlights: • Synthesis and chemical characterization of proton conductor ceramics. • Qualification of ceramics for hydrogen sensors in molten lithium–lead. • Ceramics have well-defined grains with a wide distribution of sizes. • Good agreement with predictions obtained with BaZrY, BaCeZrY and SrFeCo ceramics. -- Abstract: Tritium monitoring in lithium–lead eutectic (Pb–15.7Li) is of great importance for the performance of liquid blankets in fusion reactors. Also, tritium measurements will be required in order to proof tritium self-sufficiency in liquid metal breeding systems. On-line hydrogen (isotopes) sensors must be design and tested in order to accomplish these goals. Potentiometric hydrogen sensors for molten lithium–lead eutectic have been designed at the Electrochemical Methods Lab at Institut Quimic de Sarria (IQS) at Barcelona and are under development and qualification. The probes are based on the use of solid state electrolytes and works as proton exchange membranes (PEM). In this work the following compounds: BaZr{sub 0.9}Y{sub 0.1}O{sub 3}, BaCe{sub 0.6}Zr{sub 0.3}Y{sub 0.1}O{sub 3−α}, Sr(Ce{sub 0.6}-Zr{sub 0.4}){sub 0.9}Y{sub 0.1}O{sub 3−α} and Sr{sub 3}Fe{sub 1.8}Co{sub 2}O{sub 7} have been synthesized in order to be tested as PEM H-probes. Potentiometric measurements of the synthesized ceramic elements at 500 °C have been performed at a fixed hydrogen concentration. The sensors constructed using the proton conductor elements BaZr{sub 0.9}Y{sub 0.1}O{sub 3}, BaCe{sub 0.6}Zr{sub 0.3}Y{sub 0.1}O{sub 3−δ} and Sr{sub 3}Fe{sub 1.8}Co{sub 0.2}O{sub 7−δ} exhibited stable output potential and its value was close to the theoretical value calculated with the Nernst equation (deviation around 60 mV). In contrast, the sensor constructed using the proton conductor element Sr(Ce{sub 0.6}–Zr{sub 0.4}){sub 0.9}Y{sub 0.1}O{sub 3−δ} showed a deviation higher than 100 mV between experimental an theoretical data.

  12. Selection and optimization of spectrometric amplifiers for gamma spectrometry: part II - linearity, live time correction factors and software

    International Nuclear Information System (INIS)

    Moraes, Marco Antonio Proenca Vieira de; Pugliesi, Reinaldo

    1996-01-01

    The objective of the present work was to establish simple criteria to choose the best combination of electronic modules to achieve an adequate high resolution gamma spectrometer. Linearity, live time correction factors and softwares of a gamma spectrometric system composed by a Hp Ge detector have been studied by using several kinds of spectrometric amplifiers: Canberra 2021, Canberra 2025, Ortec 673 and Tennelec 244 and the MCA cards Ortec and Nucleus. The results showed low values of integral non-linearity for all spectrometric amplifiers connected to the Ortec and Nucleus boards. The MCA card should be able to correct amplifier dead time for 17 kcps count rates. (author)

  13. The use of car-borne gamma-ray spectrometric survey in a basin

    International Nuclear Information System (INIS)

    Liu Tengyao; Lu Shili; Luo Zongquan.

    1985-01-01

    This paper describes the geological results in a basin in the Inner Mongolia which were obtained by using our newly-developed and assembled car-borne gamma-ray spectrometric system. Combined with the work of regional geology and remote sensing, five relatively favourable uranium zones were located within the working area. The field procedures of car-borne gamma-ray spectrometry for less rigid regions is discussed. The gamma-ray spectrometric profiling is mainly used for regional reconnaissance. In the case of enhanced anomalious radioactivity the profiling with varying directions is adopted and the data are plotted on scale 1:50000 topographic map. It is suggested that the car-borne gamma-ray spectrometric system can be calibrated both by the pads specified for portable spectrometers and by testing site when the calibration facility for the car-borne gamma-ray spectrometric system is not available. The effect of rainfall on car-borne gamma-ray spectrometric survey and the simplified field qualitative determination of U-Ra disequilibrium are also briefly discussed

  14. Methodology of analysis of very weak acids by isotachophoresis with electrospray-ionization mass-spectrometric detection: Anionic electrolyte systems for the medium-alkaline pH range.

    Science.gov (United States)

    Malá, Zdena; Gebauer, Petr

    2018-01-15

    This work describes for the first time a functional electrolyte system setup for anionic isotachophoresis (ITP) with electrospray-ionization mass-spectrometric (ESI-MS) detection in the neutral to medium-alkaline pH range. So far no application was published on the analysis of very weak acids by anionic ITP-MS although there is a broad spectrum of potential analytes with pK a values in the range 5-10, where application of this technique promises interesting gains in both sensitivity and specificity. The problem so far was the lack of anionic ESI-compatible ITP systems in the mentioned pH range as all typical volatile anionic system components are fully ionized at neutral and alkaline pH and thus too fast to suit as terminators. We propose an original solution of the problem based on the combination of two ITP methods: (i) use of the hydroxyl ion as a natural and ESI-compatible terminator, and (ii) use of configurations based on moving-boundary ITP. The former method ensures effective stacking of analytes by an alkaline terminator of sufficiently low mobility and the latter offers increased flexibility for tuning of the separation window and selectivity according to actual needs. A theoretical description of the proposed model is presented and applied to the design of very simple functional electrolyte configurations. The properties of example systems are demonstrated by both computer simulation and experiments with a group of model analytes. Potential effects of carbon dioxide present in the solutions are demonstrated for particular systems. Experimental results confirm that the proposed methodology is well capable of performing sensitive and selective ITP-MS analyses of very weak acidic analytes (e.g. sulfonamides or chlorophenols). Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Potentiometric chemical sensors for the detection of paralytic shellfish toxins.

    Science.gov (United States)

    Ferreira, Nádia S; Cruz, Marco G N; Gomes, Maria Teresa S R; Rudnitskaya, Alisa

    2018-05-01

    Potentiometric chemical sensors for the detection of paralytic shellfish toxins have been developed. Four toxins typically encountered in Portuguese waters, namely saxitoxin, decarbamoyl saxitoxin, gonyautoxin GTX5 and C1&C2, were selected for the study. A series of miniaturized sensors with solid inner contact and plasticized polyvinylchloride membranes containing ionophores, nine compositions in total, were prepared and their characteristics evaluated. Sensors displayed cross-sensitivity to four studied toxins, i.e. response to several toxins together with low selectivity. High selectivity towards paralytic shellfish toxins was observed in the presence of inorganic cations with selectivity coefficients ranging from 0.04 to 0.001 for Na + and K + and 3.6*10 -4 to 3.4*10 -5 for Ca 2+ . Detection limits were in the range from 0.25 to 0.9 μmolL -1 for saxitoxin and decarbamoyl saxitoxin, and from 0.08 to 1.8 μmolL -1 for GTX5 and C1&C2, which allows toxin detection at the concentration levels corresponding to the legal limits. Characteristics of the developed sensors allow their use in the electronic tongue multisensor system for simultaneous quantification of paralytic shellfish toxins. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. Standard test methods for chemical, mass spectrometric, spectrochemical, nuclear, and radiochemical analysis of nuclear-grade plutonium nitrate solutions

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 These test methods cover procedures for the chemical, mass spectrometric, spectrochemical, nuclear, and radiochemical analysis of nuclear-grade plutonium nitrate solutions to determine compliance with specifications. 1.2 The analytical procedures appear in the following order: Sections Plutonium by Controlled-Potential Coulometry Plutonium by Amperometric Titration with Iron(II) Plutonium by Diode Array Spectrophotometry Free Acid by Titration in an Oxalate Solution 8 to 15 Free Acid by Iodate Precipitation-Potentiometric Titration Test Method 16 to 22 Uranium by Arsenazo I Spectrophotometric Test Method 23 to 33 Thorium by Thorin Spectrophotometric Test Method 34 to 42 Iron by 1,10-Phenanthroline Spectrophotometric Test Method 43 to 50 Impurities by ICP-AES Chloride by Thiocyanate Spectrophotometric Test Method 51 to 58 Fluoride by Distillation-Spectrophotometric Test Method 59 to 66 Sulfate by Barium Sulfate Turbidimetric Test Method 67 to 74 Isotopic Composition by Mass Spectrom...

  17. Characterization of solid-solution interface by potentiometric titration and electrophoretic mobility

    International Nuclear Information System (INIS)

    Lindecker, C.; Drot, R.; Fourest, B.; Simoni, E.

    1999-01-01

    The study of nuclear waste storage in deep geological sites involves the understanding of processes which could produce a possible dispersion or retention of radioelements. The dispersion of solid particles in aqueous solution is consequently important to be characterized. In this bi-phased system it is necessary to determine the characteristics of the solid-solution interface. The method used of this study is the techniques of potentiometric titration applied to heterogeneous systems. The material studied were phosphate matrices which were synthesized in the laboratory. The dependence of their surface change upon the nature of the electrolytes was investigated

  18. High-temperature mass spectrometric study of the vaporization processes and thermodynamic properties of melts in the PbO-B2O3-SiO2 system.

    Science.gov (United States)

    Stolyarova, V L; Lopatin, S I; Shilov, A L; Shugurov, S M

    2013-07-15

    The unique properties of the PbO-B2O3-SiO2 system, especially its extensive range of glass-forming compositions, make it valuable for various practical applications. The thermodynamic properties and vaporization of PbO-B2O3-SiO2 melts are not well established so far and the data obtained on these will be useful for optimization of technology and thermodynamic modeling of glasses. High-temperature Knudsen effusion mass spectrometry was used to study vaporization processes and to determine the partial pressures of components of the PbO-B2O3-SiO2 melts. Measurements were performed with a MS-1301 mass spectrometer. Vaporization was carried out using two quartz effusion cells containing the sample under study and pure PbO (reference substance). Ions were produced by electron ionization at an energy of 25 eV. To facilitate interpretation of the mass spectra, the appearance energies of ions were also measured. Pb, PbO and O2 were found to be the main vapor species over the samples studied at 1100 K. The PbO activities as a function of the composition of the system were derived from the measured PbO partial pressures. The B2O3 and SiO2 activities, the Gibbs energy of formation, the excess Gibbs energy of formation and mass losses in the samples studied were calculated. Partial pressures of the vapor species over PbO-B2O3-SiO2 melts were measured at 1100 K in the wide range of compositions using the Knudsen mass spectrometric method. The data enabled the PbO, B2O3, and SiO2 activities in these melts to be derived and provided evidence of their negative deviations from ideal behavior. Copyright © 2013 John Wiley & Sons, Ltd.

  19. Liquid chromatographic-mass spectrometric method for ...

    African Journals Online (AJOL)

    Tropical Journal of Pharmaceutical Research ... Purpose: To develop and validate a simple, efficient and reliable Liquid chromatographic-mass spectrometric (LC-MS/MS) method for the quantitative determination of two dermatological drugs, ... By Country · List All Titles · Free To Read Titles This Journal is Open Access.

  20. Spectrometric storage device in VME standard; Spektrometricheskoe zapominayushchee ustrojstvo v standarte VME

    Energy Technology Data Exchange (ETDEWEB)

    Rezaev, V E

    1996-12-31

    Paper describes module of histogram Memory Module designed to implement hardware way of accumulation of spectrometric data in systems based on VME standard equipment. Application of HMM module enables to increase throughput of the system for data acquisition and processing as in this case VME bus trunk is not occupied and may be used to control experiment course. 2 figs.

  1. Linear regression analysis of potentiometric titration data for asymmetric redox reactions

    International Nuclear Information System (INIS)

    Mar'yanov, B.M.; Gavrilenko, M.A.

    1997-01-01

    A statistical method of processing the curves of potentiometric titration for homogeneous asymmetric redox reactions has been suggested. The method was tested using a model titrimetric system Mohr's salt-K 2 Cr 2 O 7 and was employed for Te determination in an individual solution, semiconductor alloy and CdTe ceramics. Random error of the equivalence point evaluation by the data of a specific titration of 0.1-0.01 M solutions does not exceed 0.3% in case of titration of 0.001 M solutions it increases up to 1.2%. The value of s r varies from 0.0006 to 0.007

  2. Potentiometric end point detection in the EDTA titrimetric determination of gallium

    International Nuclear Information System (INIS)

    Gopinath, N.; Renuka, M.; Aggarwal, S.K.

    2001-01-01

    Gallium is titrated in presence of known amount of Fe (III) with EDTA in HNO 3 solution at pH 2 to 3. The end point is detected potentiometrically employing a bright platinum wire - saturated calomel (SCE) reference electrode system, the redox couple being Fe (III) / Fe (II). Since Fe (III) is also titrated by EDTA, it is, therefore, subtracted from titre value to get the EDTA equivalent to gallium only. Precision and accuracy 0.2 to 0.4% was obtained in the results of gallium in the range of 8 to 2 mg. (author)

  3. Improving the limits of detection in potentiometric sensors

    NARCIS (Netherlands)

    Bent, Van Der J.F.; Puik, E.C.N.; Tong, H.D.; Rijn, Van C.J.M.

    2015-01-01

    Potentiometric sensors will generally suffer from unwanted responses as a result to changing temperatures by generating an electromotive force. Typically, this voltage drift has a non-linear character and therefore it is difficult to compensate using linear algorithms implemented in the analogue

  4. Automation of potentiometric titration with a personal computer using ...

    African Journals Online (AJOL)

    sampling was designed and tested for automation of potentiometric titrations with personal ... automation permits us to carry out new types of experiments, such as those requiring ... have proved to be very useful in routine tasks but not in research, due to their ... This is done by a simple delay sub-routine in data acquisition.

  5. Stability and linearity control of spectrometric channels of the Cherenkov counters using controllable units

    International Nuclear Information System (INIS)

    Kollar, D.; Kollarova, L.; Khorvat, P.

    1976-01-01

    A system is elaborated to control stability and linearity of the Cherenkov counter spectrometric channels in an experiment on a magnetic monopole search. Linearity of a light characteristic of a photoelectric multiplier is checked with the help of the calibrated light-strikings of light emitting diodes with flare intensity adjusted by controlling generator voltage across the mercury body. A program algorithm is presented for checking stability and linearity of the Cherenkov counter spectrometric channels which helps to consider the fatigue effects of the photoelectric multiplier resulting from the considerable loads

  6. Potentiometric surface of the upper Floridan aquifer, west-central Florida, May 2011

    Science.gov (United States)

    Ortiz, Anita G.

    2011-01-01

    The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing freshwater are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is the principal source of water in the Southwest Florida Water Management District and is used for major public supply, domestic use, irrigation, and brackish water desalination in coastal communities (Southwest Florida Water Management District, 2000). This map report shows the potentiometric surface of the Upper Floridan aquifer measured in May 2011. The potentiometric surface is an imaginary surface connecting points of equal altitude to which water will rise in tightly-cased wells that tap a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the dry season, when groundwater levels usually are at an annual low and withdrawals for agricultural use typically are high. The cumulative average rainfall of 45.74 inches for west-central Florida (from June 2010 through May 2011) was 6.85 inches below the historical cumulative average of 52.59 inches (Southwest Florida Water Management District, 2011). Historical cumulative averages are calculated from regional rainfall summary reports (1915 to most recent complete calendar year) and are updated monthly by the Southwest Florida Water Management District. This report, prepared by the U.S. Geological Survey in cooperation with the Southwest Florida Water Management District, is part of a semi-annual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September from 1975 through 2010. Water-level data are collected in May and September each year to

  7. Mass spectrometric detection of radiocarbon for dating applications

    Energy Technology Data Exchange (ETDEWEB)

    Synal, H.-A., E-mail: synal@phys.ethz.ch [ETH Zurich, Laboratory of Ion Beam Physics, Building HPK, 8093 Zurich (Switzerland); Schulze-Koenig, T.; Seiler, M.; Suter, M.; Wacker, L. [ETH Zurich, Laboratory of Ion Beam Physics, Building HPK, 8093 Zurich (Switzerland)

    2013-01-15

    Radiocarbon is still the most important nuclide measured by accelerator mass spectrometry (AMS). The related capabilities for dating and tracer studies are eminent not only in archaeology but also drive important applications in the earth and environmental sciences as well as in biomedical research. So far, standard mass spectrometric systems have not been capable of radiocarbon dating because of interfering molecular isobars which, however, can be completely eliminated in charge changing processes at high ion beam energies (MeV) [1,2]. Here, we present a novel type mass spectrometry system for radiocarbon analyses. Radiocarbon dating was performed using 45 keV {sup 14}C ions from the ion source and a molecule dissociation unit kept at ground potential. This proof-of-principle experiment demonstrates for the first time the feasibility of mass spectrometric radiocarbon dating without an accelerator. The results obtained will be the basis of an optimized design for a radiocarbon dating instrument comparable in size, complexity and cost to standard mass spectrometers.

  8. Mass spectrometric detection of radiocarbon for dating applications

    International Nuclear Information System (INIS)

    Synal, H.-A.; Schulze-König, T.; Seiler, M.; Suter, M.; Wacker, L.

    2013-01-01

    Radiocarbon is still the most important nuclide measured by accelerator mass spectrometry (AMS). The related capabilities for dating and tracer studies are eminent not only in archaeology but also drive important applications in the earth and environmental sciences as well as in biomedical research. So far, standard mass spectrometric systems have not been capable of radiocarbon dating because of interfering molecular isobars which, however, can be completely eliminated in charge changing processes at high ion beam energies (MeV) [1,2]. Here, we present a novel type mass spectrometry system for radiocarbon analyses. Radiocarbon dating was performed using 45 keV 14 C ions from the ion source and a molecule dissociation unit kept at ground potential. This proof-of-principle experiment demonstrates for the first time the feasibility of mass spectrometric radiocarbon dating without an accelerator. The results obtained will be the basis of an optimized design for a radiocarbon dating instrument comparable in size, complexity and cost to standard mass spectrometers.

  9. Mass spectrometric detection of radiocarbon for dating applications

    Science.gov (United States)

    Synal, H.-A.; Schulze-König, T.; Seiler, M.; Suter, M.; Wacker, L.

    2013-01-01

    Radiocarbon is still the most important nuclide measured by accelerator mass spectrometry (AMS). The related capabilities for dating and tracer studies are eminent not only in archaeology but also drive important applications in the earth and environmental sciences as well as in biomedical research. So far, standard mass spectrometric systems have not been capable of radiocarbon dating because of interfering molecular isobars which, however, can be completely eliminated in charge changing processes at high ion beam energies (MeV) [1,2]. Here, we present a novel type mass spectrometry system for radiocarbon analyses. Radiocarbon dating was performed using 45 keV 14C ions from the ion source and a molecule dissociation unit kept at ground potential. This proof-of-principle experiment demonstrates for the first time the feasibility of mass spectrometric radiocarbon dating without an accelerator. The results obtained will be the basis of an optimized design for a radiocarbon dating instrument comparable in size, complexity and cost to standard mass spectrometers.

  10. Development of a portable mass spectrometric system for determination of isotopic composition of solid uranium samples using fluorine volatilization. Final report

    International Nuclear Information System (INIS)

    Loge, G.

    1994-01-01

    Using hardware and materials supplied by LANL, a prototype quadrupole mass spectrometer system designed for portable field analysis of isotopic composition of solid uranium samples was assembled and tested. The system contained the capability for fluorine volatilization of solid uranium samples with gas introduction, which was successfully tested and demonstrated using 100 mg samples of U 3 O 8 . Determination of precision and accuracy for measuring isotopic composition was performed using isotopic standards. Use with soil samples containing uranium were also attempted. Silicates in the soil forming SiF 4 were found to be a kinetic bottleneck to the formation of UF 6 . This could be avoided by performing some sort of chemical separation as a pre-treatment step, which was demonstrated using nitric acid

  11. Gamma-spectrometric analysis of river sediments collected around phosphate fertilizer industries

    International Nuclear Information System (INIS)

    Gallardo, M.C.; Garcia-Leon, M.; Mundi, M.; Respaldiza, M.A.

    1993-01-01

    Gamma-ray spectrometric analysis has been carried out on sediments collected in an estuarine system formed by two major rivers in southern Spain. The results show clearly that important amounts of natural radioactivity are accumulating on the bed of both rivers. This radioactivity appears to originate from effluent from several phoshate fertilizer factories adjacent to the estuary. (author)

  12. On the Origin of Microheterogeneity : A Mass Spectrometric Study of Dimethyl Sulfoxide-Water Binary Mixture

    NARCIS (Netherlands)

    Shin, Dong Nam; Wijnen, Jan W.; Engberts, Jan B.F.N.; Wakisaka, Akihiro

    2001-01-01

    We have studied the microscopic solvent structure of dimethyl sulfoxide-water mixtures and its influence on the solvation structure of solute from a clustering point of View, by means of a specially designed mass spectrometric system. It was observed that the propensity to the cluster formation is

  13. Potentiometric Surface of the Upper Floridan Aquifer in the St. Johns River Water Management District and Vicinity, Florida, May 2009

    Science.gov (United States)

    Kinnaman, Sandra L.; Dixon, Joann F.

    2009-01-01

    This map depicts the potentiometric surface of the Upper Floridan aquifer in the St. Johns River Water Management District and vicinity for May 2009. Potentiometric contours are based on water-level measurements collected at 625 wells during the period May 14 - May 29, near the end of the dry season. Some contours are inferred from previous potentiometric-surface maps with larger well networks. The potentiometric surface of the carbonate Upper Floridan aquifer responds mainly to rainfall, and more locally, to groundwater withdrawals and spring flow. Potentiometric-surface highs generally correspond to topographic highs where the aquifer is recharged. Springs and areas of diffuse upward leakage naturally discharge water from the aquifer and are most prevalent along the St. Johns River. Areas of discharge are reflected by depressions in the potentiometric surface. Groundwater withdrawals locally have lowered the potentiometric surface. Groundwater in the Upper Floridan aquifer generally flows from potentiometric highs to potentiometric lows in a direction perpendicular to the contours.

  14. Potentiometric Surface of the Upper Floridan Aquifer in the St. Johns River Water Management District and Vicinity, Florida, May 2005

    Science.gov (United States)

    Kinnaman, Sandra L.

    2006-01-01

    INTRODUCTION This map depicts the potentiometric surface of the upper Floridan aquifer in the St. Johns River Water Management District and vicinity for May 2005. Potentiometric contours are based on water level measurements collected at 598 wens during the period May 5 - 31, near the end of the dry season. Some contours are inferred from previous potentiometric-surface maps with larger well networks. The potentiometric surface of the carbonate upper Floridan aquifer responds mainly to rainfall, and more locally, to ground water withdrawals. Potentiometric-surface highs generally correspond to topographic highs where the aquifer is recharged. Springs and areas of diffuse upward leakage naturally discharge water from the aquifer and are most prevalent along the St. Johns River. Areas of discharge are reflected by depressions in the potentiometric surface. Ground water withdrawals locally have lowered the potentiometric surface. Ground water in the upper Floridan aquifer generally flows from potentiometric highs to potentiometric lows in a direction perpendicular to the contours.

  15. Processing of gamma-ray spectrometric logs

    International Nuclear Information System (INIS)

    Umiastowski, K.; Dumesnil, P.

    1984-10-01

    CEA (Commissariat a l'Energie Atomique) has developped a gamma-ray spectrometric tool, containing an analog-to-digital converter. This new tool permits to perform very precise uranium logs (natural gamma-ray spectrometry), neutron activation logs and litho-density logs (gamma-gamma spectrometric logs). Specific processing methods were developped to treate the particular problems of down-hole gamma-ray spectrometry. Extraction of the characteristic gamma-ray peak, even if they are superposed on the background radiation of very high intensity, is possible. This processing methode enables also to obtain geological informations contained in the continuous background of the spectrum. Computer programs are written in high level language for SIRIUS (VICTOR) and APOLLO computers. Exemples of uranium and neutron activation logs treatment are presented [fr

  16. Preparation and mass spectrometrical high temperature investigations on compounds of the quasi-ternary system Cs2O-Al2O3-SiO2

    International Nuclear Information System (INIS)

    Odoj, R.; Hilpert, K.; Nuernberg, H.W.

    1977-09-01

    Additions of aluminium oxide and silicen oxide to ceramic fuel for pyrocarbon-coated nuclear fuel paticles counteract a release of fission-cesium by compound formation. The vapourization tests carried out here using samples from the quasi-ternary system cesium-oxide-aluminium-oxide-silicon-oxide by means of high-temperature mass spectroscopy using a Knudsen cell served the optimization of this retention effect. The aim of the apparative changes on the knudsen cell were to shield heat radiation on the temperature measuring borehole through the tungsten wire cathode in order to be able to perform exact temperature measurements even below 1,000 0 C. A new method of preparation was developed to obtain defined cesium aluminium silicates whose composition was determined by Guinier and goniometer pictures as well as by microscopic investigations. According to the latter, 3 ternary compounds are present in the system investigated: CsAlSiO 4 , CsAlSi 2 O 6 and CsAlSi 5 O 12 . Their lattice constants were determined from goniometric measurements; the vapour pressure equection were set up from the measured cesium vapour pressure values over each sample and the enthalpies of the vapourization reactions were found to be 84 kcal for CsAlSiO 4 at 1,400 0 K, 100 kcal for CsAlSi 2 O 6 at 1,550 0 K and 122 kcal for CsAlSi 5 O 12 at 1,650 0 K. The cesium vapour pressures of the glas phases investigated of the system are above the Cs partial pressures of the solid crystalline phases of the same composition. The results of the work explain the causes of the reduction of the Cs release and show that the vapour pressure can be lowered by more than 10 orders of magnitude at reactor relevant temperatures by compound formation. (RB) [de

  17. Fabrication of SO/sub 2/preparation system and calibration of PINSTECH sulfur standard for /sup 34/S/sup 32/S mass spectrometric analysis

    International Nuclear Information System (INIS)

    Sajjad, M.I.; Latif, Z.; Ali, M.; Qureshi, R.M.; Tasneem, M.A.; Khan, I.H.; Ahmed, M.; Ahmed, I.

    1994-05-01

    This report describes the fabrication and standardization of operation procedures of a SO/sub 2/ preparation system used for the extraction of sulfur dioxide gas from sulfur minerals (aqueous sulfate, elemental sulfur, and sulfides) for sulfur isotope ratio measurements on a gas source mass spectrometer for hydrological, geological and environmental applications. SO/sub 2/ preparation procedure as described by Fumitaka Yanagisawa and Hitoshi Sakai (1983) is adopted with some modifications. A chemically pure BaSO/sub 4/ powder is chosen as PINSTECH Sulfur Standard PSS-I for routine laboratory /sup 34/S analysis. PSS-1 is calibrated against the International Atomic Energy Agency (IAEA) standard Cannon Diablo Troilite (CDT) using the NBS-127 sulfur standard Sigma /sup 34/S values of PSS-1 as analyzed at PINSTECH and Institute fur Hydorlogie, Munich are found to be 14.58 +-0.07 % CDT (n=6) and 14.59+-0.15% CDT (n=2) respectively. NBS-127 is BaSO/sub 4/ powder from the National Bureau of Standards, USA and has been calibrated against CDT. Interlaboratory comparison of various standards is also documented. Using this system, the reproducibility of sulfur isotope ratio measurements is better than +-0.2 % (n=10). (author)

  18. Fabrication of SO/sub 2/preparation system and calibration of PINSTECH sulfur standard for /sup 34/S/sup 32/S mass spectrometric analysis

    Energy Technology Data Exchange (ETDEWEB)

    Sajjad, M I; Latif, Z; Ali, M; Qureshi, R M; Tasneem, M A; Khan, I H; Ahmed, M; Ahmed, I

    1994-05-01

    This report describes the fabrication and standardization of operation procedures of a SO/sub 2/ preparation system used for the extraction of sulfur dioxide gas from sulfur minerals (aqueous sulfate, elemental sulfur, and sulfides) for sulfur isotope ratio measurements on a gas source mass spectrometer for hydrological, geological and environmental applications. SO/sub 2/ preparation procedure as described by Fumitaka Yanagisawa and Hitoshi Sakai (1983) is adopted with some modifications. A chemically pure BaSO/sub 4/ powder is chosen as PINSTECH Sulfur Standard PSS-I for routine laboratory /sup 34/S analysis. PSS-1 is calibrated against the International Atomic Energy Agency (IAEA) standard Cannon Diablo Troilite (CDT) using the NBS-127 sulfur standard Sigma /sup 34/S values of PSS-1 as analyzed at PINSTECH and Institute fur Hydorlogie, Munich are found to be 14.58 +-0.07 % CDT (n=6) and 14.59+-0.15% CDT (n=2) respectively. NBS-127 is BaSO/sub 4/ powder from the National Bureau of Standards, USA and has been calibrated against CDT. Interlaboratory comparison of various standards is also documented. Using this system, the reproducibility of sulfur isotope ratio measurements is better than +-0.2 % (n=10). (author).

  19. Electronic equipment for spectrometric data processing

    International Nuclear Information System (INIS)

    Antonov, L.J.; Trenev, A.M.; Todorova, E.I.; Dimitrov, V.D.

    1978-01-01

    Electronic equipment carrying out logical operations and a full set of the arithmetic operations was developed for spectrometric data processing. The flowsheet of the computing part of the device, made on the basis of a specialized integral circuit, is given. The device includes input registers, multiplexor, matrix commutator, arithmetic unit and indication unit. The equipment is rated to carry out calculations according to comparatively complex formulae in several seconds

  20. Determination of the total acidity in soft drinks using potentiometric sequential injection titration.

    Science.gov (United States)

    van Staden, J Koos F; Mashamba, M Mulalo G; Stefan, R Raluca I

    2002-12-06

    A potentiometric SI titration system for the determination of total acidity in soft drinks is proposed. The concept is based on the aspiration of the acid soft drink sample between two base zones into a holding coil with the volume of the first base zone twice to that of the second one and channelled by flow reversal through a reaction coil to a potentiometric sensor. A solution of 0.1 mol l(-1) sodium chloride is used as ionic strength adjustment buffer in the carrier stream. The system has been applied to the analysis of some South African soft drinks having a total acidity level of about 0.2-0.3% (w/v). The method has a sample frequency of 45 samples per h with a linear range of 0.1 and 0.6% (w/v). It is easy to use, fully computerised, and gives the results that are comparable to both automated batch titration and manual titration.

  1. A new potentiometric method for the estimation of the rare earth elements

    International Nuclear Information System (INIS)

    Selig, W.S.

    1988-01-01

    Chinese workers recently described a new potentiometric method for lead using sodium tetraphenylborate (NaTPB) as a titrant. Based on a previous Chinese publication, the authors have recently developed a method for the estimation of the alkaline earth metals by sequential titration with NaTPB. In the present work, the authors report a similar method for the estimation of the rare earth elements, including Sc and Y. The sensing electrode is a spectrographic graphite rod, coated with a solution of poly(vinyl chloride) and dioctylphthalate in tetrahydrofuran as previously described. The reference electrode was a double-junction Ag/AgCl electrode. The titration system is controlled by a Tektronix 4051 graphics computer system. Single cations or mixtures up to 0.5 mequiv are determined by potentiometric titration with 0.05 N NaTPB, after formation of the oxonium cations by reaction with an aqueous solution of poly(ethylene glycol) (PEG). Best results are obtained with PEGs of molecular weights from 8,000 to 20,000. Sequential estimation of Pb + Ba, Sr, and Ca, and the sum of the rare earth elements is also reported, plus possible applications to Al, Ga, and anions precipitated by lead

  2. Role of neuropeptide Y in the regulation of gonadotropin releasing hormone system in the forebrain of Clarias batrachus (Linn.): immunocytochemistry and high performance liquid chromatography-electrospray ionization-mass spectrometric analysis.

    Science.gov (United States)

    Gaikwad, A; Biju, K C; Muthal, P L; Saha, S; Subhedar, N

    2005-01-01

    Although the importance of neuropeptide Y (NPY) in the regulation of gonadotropin releasing hormone (GnRH) and reproduction has been highlighted in recent years, the neuroanatomical substrate within which these substances might interact has not been fully elucidated. Present work was undertaken with a view to define the anatomical-physiological correlates underlying the role exercised by NPY in the regulation of GnRH in the forebrain of the teleost Clarias batrachus. Application of double immunocytochemistry revealed close associations as well as colocalizations of the two peptides in the olfactory receptor neurons (ORNs), olfactory nerve fibers and their terminals in the glomeruli, ganglion cells of nervus terminalis, medial olfactory tract, fibers in the area ventralis telencephali/pars supracommissuralis and cells as well as fibers in the pituitary. NPY containing axons were found to terminate in the vicinity of GnRH cells in the pituitary with light as well as electron microscopy. Double immunoelectron microscopy demonstrated gold particles for NPY and GnRH colocalized on the membrane and in dense core of the secretory granules in the cells distributed in all components of the pituitary gland. To assess the physiological implication of these observations, NPY was injected via the intracranial route and the response of GnRH immunoreactive system was evaluated by relative quantitative morphometry as well as high performance liquid chromatography (HPLC) analysis. Two hours following NPY (20 ng/g body weight) administration, a dramatic increase was observed in the GnRH immunoreactivity in the ORNs, in the fibers of the olfactory bulb (163%) and medial olfactory tract (351%). High performance liquid chromatography-electrospray ionization-mass spectrometric analysis confirmed the immunocytochemical data. Significant rise in the salmon GnRH (sGnRH)-like peptide content was observed in the olfactory organ (194.23%), olfactory bulb (146.64%), telencephalon+preoptic area

  3. Towards absolute quantification of allergenic proteins in food--lysozyme in wine as a model system for metrologically traceable mass spectrometric methods and certified reference materials.

    Science.gov (United States)

    Cryar, Adam; Pritchard, Caroline; Burkitt, William; Walker, Michael; O'Connor, Gavin; Burns, Duncan Thorburn; Quaglia, Milena

    2013-01-01

    Current routine food allergen quantification methods, which are based on immunochemistry, offer high sensitivity but can suffer from issues of specificity and significant variability of results. MS approaches have been developed, but currently lack metrological traceability. A feasibility study on the application of metrologically traceable MS-based reference procedures was undertaken. A proof of concept involving proteolytic digestion and isotope dilution MS for quantification of protein allergens in a food matrix was undertaken using lysozyme in wine as a model system. A concentration of lysozyme in wine of 0.95 +/- 0.03 microg/g was calculated based on the concentrations of two peptides, confirming that this type of analysis is viable at allergenically meaningful concentrations. The challenges associated with this promising method were explored; these included peptide stability, chemical modification, enzymatic digestion, and sample cleanup. The method is suitable for the production of allergen in food certified reference materials, which together with the achieved understanding of the effects of sample preparation and of the matrix on the final results, will assist in addressing the bias of the techniques routinely used and improve measurement confidence. Confirmation of the feasibility of MS methods for absolute quantification of an allergenic protein in a food matrix with results traceable to the International System of Units is a step towards meaningful comparison of results for allergen proteins among laboratories. This approach will also underpin risk assessment and risk management of allergens in the food industry, and regulatory compliance of the use of thresholds or action levels when adopted.

  4. Formation of mixed hydroxides in the thorium chloride-iron chloride-sodium hydroxide system

    International Nuclear Information System (INIS)

    Krivokhatskij, A.S.; Prokudina, A.F.; Sapozhnikova, T.V.

    1976-01-01

    The process of formation of mixed hydroxides in the system thorium chloride-iron chloride-NaOH was studied at commensurate concentrations of Th and Fe in solution (1:1 and 1:10 mole fractions, respectively) with ionic strength 0.3, 2.1, and 4.1, created with the electrolyte NaCl, at room temperature 22+-1degC. By the methods of chemical, potentiometric, thermographic, and IR-spectrometric analyses, it was shown that all the synthesized precipitates are mechanical mixtures of two phases - thorium hydroxide and iron hydroxide - and not a new hydrated compound. The formal solubility of the precipitates of mixed hydroxides was determined. It was shown that the numerical value of the formal solubility depends on the conditions of formation and age of the precipitates

  5. A biosorption system for metal ions on Penicillium italicum - loaded on Sepabeads SP 70 prior to flame atomic absorption spectrometric determinations

    International Nuclear Information System (INIS)

    Mendil, Durali; Tuzen, Mustafa; Soylak, Mustafa

    2008-01-01

    A solid phase extraction (SPE) preconcentration system, coupled to a flame atomic absorption spectrometer (FAAS), was developed for the determination of copper(II), cadmium(II), lead(II), manganese(II), iron(III), nickel(II) and cobalt(II) ions at the μg L -1 levels on Penicillium italicum - loaded on Sepabeads SP 70. The analytes were adsorbed on biosorbent at the pH range of 8.5-9.5. The adsorbed metals were eluted with 1 mol L -1 HCl. The influences of the various analytical parameters including pH of the aqueous solutions, sample volume, flow rates were investigated for the retentions of the analyte ions. The recovery values are ranged from 95-102%. The influences of alkaline, earth alkaline and some transition metal ions were also discussed. Under the optimized conditions, the detection limits (3 s, n = 21) for analytes were in the range of 0.41 μg L -1 (cadmium) and 1.60 μg L -1 (iron). The standard reference materials (IAEA 336 Lichen, NIST SRM 1573a Tomato leaves) were analyzed to verify the proposed method. The method was successfully applied for the determinations of analytes in natural water, cultivated mushroom, lichen (Bryum capilare Hedw), moss (Homalothecium sericeum) and refined table salt samples

  6. A biosorption system for metal ions on Penicillium italicum - loaded on Sepabeads SP 70 prior to flame atomic absorption spectrometric determinations

    Energy Technology Data Exchange (ETDEWEB)

    Mendil, Durali; Tuzen, Mustafa [Gaziosmanpasa University, Faculty of Science and Arts, Chemistry Department, 60250 Tokat (Turkey); Soylak, Mustafa [Erciyes University, Faculty of Science and Arts, Chemistry Department, 38039 Kayseri (Turkey)], E-mail: msoylak@gmail.com

    2008-04-15

    A solid phase extraction (SPE) preconcentration system, coupled to a flame atomic absorption spectrometer (FAAS), was developed for the determination of copper(II), cadmium(II), lead(II), manganese(II), iron(III), nickel(II) and cobalt(II) ions at the {mu}g L{sup -1} levels on Penicillium italicum - loaded on Sepabeads SP 70. The analytes were adsorbed on biosorbent at the pH range of 8.5-9.5. The adsorbed metals were eluted with 1 mol L{sup -1} HCl. The influences of the various analytical parameters including pH of the aqueous solutions, sample volume, flow rates were investigated for the retentions of the analyte ions. The recovery values are ranged from 95-102%. The influences of alkaline, earth alkaline and some transition metal ions were also discussed. Under the optimized conditions, the detection limits (3 s, n = 21) for analytes were in the range of 0.41 {mu}g L{sup -1} (cadmium) and 1.60 {mu}g L{sup -1} (iron). The standard reference materials (IAEA 336 Lichen, NIST SRM 1573a Tomato leaves) were analyzed to verify the proposed method. The method was successfully applied for the determinations of analytes in natural water, cultivated mushroom, lichen (Bryum capilare Hedw), moss (Homalothecium sericeum) and refined table salt samples.

  7. A systems wide mass spectrometric based linear motif screen to identify dominant in-vivo interacting proteins for the ubiquitin ligase MDM2.

    Science.gov (United States)

    Nicholson, Judith; Scherl, Alex; Way, Luke; Blackburn, Elizabeth A; Walkinshaw, Malcolm D; Ball, Kathryn L; Hupp, Ted R

    2014-06-01

    Linear motifs mediate protein-protein interactions (PPI) that allow expansion of a target protein interactome at a systems level. This study uses a proteomics approach and linear motif sub-stratifications to expand on PPIs of MDM2. MDM2 is a multi-functional protein with over one hundred known binding partners not stratified by hierarchy or function. A new linear motif based on a MDM2 interaction consensus is used to select novel MDM2 interactors based on Nutlin-3 responsiveness in a cell-based proteomics screen. MDM2 binds a subset of peptide motifs corresponding to real proteins with a range of allosteric responses to MDM2 ligands. We validate cyclophilin B as a novel protein with a consensus MDM2 binding motif that is stabilised by Nutlin-3 in vivo, thus identifying one of the few known interactors of MDM2 that is stabilised by Nutlin-3. These data invoke two modes of peptide binding at the MDM2 N-terminus that rely on a consensus core motif to control the equilibrium between MDM2 binding proteins. This approach stratifies MDM2 interacting proteins based on the linear motif feature and provides a new biomarker assay to define clinically relevant Nutlin-3 responsive MDM2 interactors. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. Potentiometric sensors using cotton yarns, carbon nanotubes and polymeric membranes.

    Science.gov (United States)

    Guinovart, Tomàs; Parrilla, Marc; Crespo, Gastón A; Rius, F Xavier; Andrade, Francisco J

    2013-09-21

    A simple and generalized approach to build electrochemical sensors for wearable devices is presented. Commercial cotton yarns are first turned into electrical conductors through a simple dyeing process using a carbon nanotube ink. These conductive yarns are then partially coated with a suitable polymeric membrane to build ion-selective electrodes. Potentiometric measurements using these yarn-potentiometric sensors are demonstrated. Examples of yarns that can sense pH, K(+) and NH4(+) are presented. In all cases, these sensing yarns show limits of detection and linear ranges that are similar to those obtained with lab-made solid-state ion-selective electrodes. Through the immobilization of these sensors in a band-aid, it is shown that this approach could be easily implemented in a wearable device. Factors affecting the performance of the sensors and future potential applications are discussed.

  9. Simple home-made sensors for potentiometric titrations

    International Nuclear Information System (INIS)

    Selig, W.

    1982-04-01

    A sensor for potentiometric titrations was prepared by coating a spectroscopic graphite rod with a solution of poly(vinyl chloride) and dioctyphthalate in tetrahydrofuran. The reference electrode was an Ag/AgCl single-junction electrode. The sensor was used in precipitation, acid-base, compleximetric, and redox titrations. Preparation of the coated-graphite sensor is simple and rapid. Moreover, it is quite inexpensive. A limitation is its applicability in aqueous media only, because organic solvents will dissolve the membrane. Various uncoated types of graphite have also been investigated as sensors, particularly in two applications of interest in the analysis of propellants: the titration of nitroform and perchlorate. Obviously, these sensors can be used also in nonaqueous, or partially nonaqueous media. These sensors may also find use in the potentiometric titration of fluoride vs La(III) or Th

  10. Characterization of Native and Modified Starches by Potentiometric Titration

    OpenAIRE

    Soto, Diana; Urdaneta, Jose; Pernia, Kelly

    2014-01-01

    The use of potentiometric titration for the analysis and characterization of native and modified starches is highlighted. The polyelectrolytic behavior of oxidized starches (thermal and thermal-chemical oxidation), a graft copolymer of itaconic acid (IA) onto starch, and starch esters (mono- and diester itaconate) was compared with the behavior of native starch, the homopolymer, and the acid employed as a graft monomer and substituent. Starch esters showed higher percentages of acidity, follo...

  11. Fluorinated tripodal receptors for potentiometric chloride detection in biological fluids.

    Science.gov (United States)

    Pankratova, Nadezda; Cuartero, Maria; Jowett, Laura A; Howe, Ethan N W; Gale, Philip A; Bakker, Eric; Crespo, Gastón A

    2018-01-15

    Fluorinated tripodal compounds were recently reported to be efficient transmembrane transporters for a series of inorganic anions. In particular, this class of receptors has been shown to be suitable for the effective complexation of chloride, nitrate, bicarbonate and sulfate anions via hydrogen bonding. The potentiometric properties of urea and thiourea-based fluorinated tripodal receptors are explored here for the first time, in light of the need for reliable sensors for chloride monitoring in undiluted biological fluids. The ion selective electrode (ISE) membranes with tren-based tris-urea bis(CF 3 ) tripodal compound (ionophore I) were found to exhibit the best selectivity for chloride over major lipophilic anions such as salicylate ( [Formula: see text] ) and thiocyanate ( [Formula: see text] ). Ionophore I-based ISEs were successfully applied for chloride determination in undiluted human serum as well as artificial serum sample, the slope of the linear calibration at the relevant background of interfering ions being close to Nernstian (49.8±1.7mV). The results of potentiometric measurements were confirmed by argentometric titration. Moreover, the ionophore I-based ISE membrane was shown to exhibit a very good long-term stability of potentiometric performance over the period of 10 weeks. Nuclear magnetic resonance (NMR) titrations, potentiometric sandwich membrane experiments and density functional theory (DFT) computational studies were performed to determine the binding constants and suggest 1:1 complexation stoichiometry for the ionophore I with chloride as well as salicylate. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Potentiometric-surface map, 1993, Yucca Mountain and vicinity, Nevada

    International Nuclear Information System (INIS)

    Tucci, P.; Burkhardt, D.J.

    1995-01-01

    The revised potentiometric surface map here, using mainly 1993 average water levels, updates earlier maps of this area. Water levels are contoured with 20-m intervals, with additional 0.5-m contours in the small-gradient area SE of Yucca Mountain. Water levels range from 728 m above sea level SE of Yucca to 1,034 m above sea level north of Yucca. Potentiometric levels in the deeper parts of the volcanic rock aquifer range from 730 to 785 m above sea level. The potentiometric surface can be divided into 3 regions: A small gradient area E and SE of Yucca, a moderate-gradient area on the west side of Yucca, and a large-gradient area to the N-NE of Yucca. Water levels from wells at Yucca were examined for yearly trends (1986-93) using linear least-squares regression. Of the 22 wells, three had significant positive trends. The trend in well UE-25 WT-3 may be influenced by monitoring equipment problems. Tends in USW WT-7 and USW WTS-10 are similar; both are located near a fault west of Yucca; however another well near that fault exhibited no significant trend

  13. Potentiometric Surface of the Upper Floridan Aquifer, West-Central Florida, May 2006

    Science.gov (United States)

    Ortiz, A.G.

    2007-01-01

    Introduction Hydrologic Conditions in West-Central Florida The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing fresh water are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is the principal source of water in the Southwest Florida Water Management District and is used for major public supply, domestic use, irrigation, and brackish water desalination in coastal communities (Southwest Florida Water Management District, 2000). This map report shows the potentiometric surface of the Upper Floridan aquifer measured in May 2006. The potentiometric surface is an imaginary surface connecting points of equal altitude to which water will rise in tightly-cased wells that tap a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the dry season, when ground-water levels usually are at an annual low and withdrawals for agricultural use typically are high. The cumulative average rainfall of 50.23 inches for west-central Florida (from June 2005 through May 2006) was 2.82 inches below the historical cumulative average of 53.05 inches (Southwest Florida Water Management District, 2006). Historical cumulative averages are calculated from regional rainfall summary reports (1915 to most recent complete calendar year) and are updated monthly by the Southwest Florida Water Management District. This report, prepared by the U.S. Geological Survey in cooperation with the Southwest Florida Water Management District, is part of a semi-annual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric-surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September since 1975. Water

  14. Spectrometric control of radionuclides production parameters

    International Nuclear Information System (INIS)

    Zhuk, I.; Potarenko, A.; Yarochevich, O.; Hluboky, N.; Kerko, P.; Bogdanov, V.; Dyatel, N.

    2006-01-01

    Full text: A radioactive preparations and sources are widely used all over the world for scientific, industrial and medical purposes. These preparations in Belarus are planned to produce by the Joint Belarussian-Russian Closed Joint Stock Company 'Isotope technologies' (CJSC IT). The company was created in 1998 by two leading scientific centers-SSI 'Joint Institute of Power and Nuclear Research-Sosny' the National Academy of Sciences of Belarus and the State Center of Science of the Russian Federation 'Scientific research institute of nuclear reactors'. One of the mainstream directions in CJSC IT activities is production of radioactive preparations for the industrial and scientific application (such as 133 Ba, 109 Cd, 63 Ni, 60 Co) and for the medical purposes (such as 19 '2Ir, 60 Co). All radioactive preparations have a good export potential and adequate to modern technical and consumer requirements. X-γ spectrometric analysis of considered radioactive sources is one of the basic methods for quality control of radioactive sources. At present, we are developing x-γ spectrometric support of purification process from contaminating radionuclides of 109 Cd -γ preparation and 63 Ni - β preparation. Work on x-γ spectrometric quality control of 133 Ba preparation is carried out. The description of the used equipment is given. Techniques of contaminating radionuclides determination (contents ∼10 - '6 from activity of the basic radionuclide) are presented. Problems of the choice of geometry of measurements of sources with activity about 10 7 -10 9 Bq and possible sources of errors are discussed. (author)

  15. A measuring generator for testing spectrometric channels

    International Nuclear Information System (INIS)

    Dinh Sy Hien; Kalinkin, A.I.

    1984-01-01

    A measuring generator for testing and tuning an amplitude spectrometric channel is described. The device consists of a pseudo random pulse generator, constructed on shifters, a sawtooth wave generator and a shaper of stable amplitude pulses with exponential decay times. The device is made as CAMAC unit width modules and has the following specifications: average pulse repetition rate of pseudo random pulses is 3.1; 25; 50; 100; 200 kHz; peak amplitude of 2 Hz pulse repetition of saw tooth pulses is 6 V; peak amplitude of exponential shape pulses is 5 V. The block-diagram and basic circuits of the device are given

  16. Standard test methods for chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade mixed oxides ((U, Pu)O2)

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 These test methods cover procedures for the chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade mixed oxides, (U, Pu)O2, powders and pellets to determine compliance with specifications. 1.2 The analytical procedures appear in the following order: Sections Uranium in the Presence of Pu by Potentiometric Titration Plutonium by Controlled-Potential Coulometry Plutonium by Amperometric Titration with Iron (II) Nitrogen by Distillation Spectrophotometry Using Nessler Reagent 7 to 14 Carbon (Total) by Direct Combustion-Thermal Conductivity 15 to 26 Total Chlorine and Fluorine by Pyrohydrolysis 27 to 34 Sulfur by Distillation-Spectrophotometry 35 to 43 Moisture by the Coulometric, Electrolytic Moisture Analyzer 44 to 51 Isotopic Composition by Mass Spectrometry Rare Earths by Copper Spark Spectroscopy 52 to 59 Trace Impurities by Carrier Distillation Spectroscopy 60 to 69 Impurities by Spark-Source Mass Spectrography 70 to 76 Total Gas in Reactor-Grade Mixed Dioxide P...

  17. Potentiometric investigation of acid dissociation and anionic homoconjugation equilibria of substituted phenols in dimethyl sulfoxide

    International Nuclear Information System (INIS)

    Czaja, Malgorzata; Kozak, Anna; Makowski, Mariusz; Chmurzynski, Lech.

    2003-01-01

    Standard acidity constants, K a DMSO (HA), expressed as pK a DMSO (HA) values, and anionic homoconjugation constants, K DMSO AHA - , (in the form of lg K DMSO AHA - values) have been determined for 11 substituted phenol-phenolate systems a polar protophilic aprotic solvent, dimethyl sulfoxide (DMSO) with a potentiometric titration. A linear relationship has been determined between lg K DMSO AHA - and pK a DMSO (HA). The tendency towards anionic homoconjugation in these systems increases with increasing pK a DMSO (HA) that is with declining phenol acidity. The pK a DMSO (HA) are correlated with both pK a W (HA) water and other polar non-aqeous solvents

  18. Open-Source Low-Cost Wireless Potentiometric Instrument for pH Determination Experiments

    Science.gov (United States)

    Jin, Hao; Qin, Yiheng; Pan, Si; Alam, Arif U.; Dong, Shurong; Ghosh, Raja; Deen, M. Jamal

    2018-01-01

    pH determination is an essential experiment in many chemistry laboratories. It requires a potentiometric instrument with extremely low input bias current to accurately measure the voltage between a pH sensing electrode and a reference electrode. In this technology report, we propose an open-source potentiometric instrument for pH determination…

  19. Mass Spectrometric Analysis for Nuclear Safeguards

    International Nuclear Information System (INIS)

    Boulyga, S.

    2013-01-01

    The release of man-made radionuclides into the environment results in contamination that carries specific isotopic signatures according to the release scenarios and the previous usage of materials and facilities. In order to trace the origin of such contamination and/or to assess the potential impact on the public and environmental health, it is necessary to determine the isotopic composition and activity concentrations of radionuclides in environmental samples in an accurate and timely fashion. Mass spectrometric techniques, such as thermal ionization mass spectrometry (TIMS), secondary ion mass spectrometry (SIMS), and inductively coupled plasma mass spectrometry (ICP-MS) belong to the most powerful methods for analysis of nuclear and related samples in nuclear safeguards, forensics, and environmental monitoring. This presentation will address the potential of mass spectrometric analysis of actinides at ultra-trace concentration levels, isotopic analysis of micro-samples, age determination of nuclear materials as well as identification and quantification of elemental and isotopic signatures of nuclear samples in general. (author)

  20. Potentiometric determination of hexavalent uranium in uranium silicide samples

    International Nuclear Information System (INIS)

    Arlegui, Oscar

    1999-01-01

    The Chilean Nuclear Energy Commission's Department of Nuclear Materials has among its projects the production of fuels elements for nuclear reactors, and, therefore, the Chemical Analysis Laboratory must have a rapid and reliable method for uranium analysis, to control the uranium concentration during each stage of the production process. For this reason the Chilean Nuclear Energy Commission's Chemical Analysis Laboratory has validated a potentiometric method, which is a modification of the Davies and Gray method proposed by A.R. Eberle. This method uses the Potentiometric Titration Technique and is based on the direct and rapid reduction of uranium (VI) to Uranium (IV), in a concentrated phosphoric acid medium, with excess iron (II) used as a reducing agent. In this medium the excess iron (II) selectively oxidizes to iron (III) with nitric acid, using molybdenum (IV) as a catalyzer, the nitrous acid that is produced is eliminated by adding amidosulfuric acid. The solution is diluted with 1M sulfuric acid and the uranium (IV) obtained is titrated potentiometrically with potassium dichromate in the presence of vanadilic sulfate to obtain a better defined final titration point. The samples were softened with hydrochloric acid and nitric acid and later 50 ml were estimated in a 20% sulfuric acid medium. The analytical method was validated by comparing it with Certified Reference Material (C.R.M.) from the New Brunswick Laboratory (NBL), Metallic Uranium, CRM 112-A. The F Test and the T Test show that the value calculated is less than the tabulated value so the result is traceable to the reference material. The quantification limit, sensitivity, precision and accuracy were quantified for the method

  1. Determination of milligram amounts of neptunium by potentiometric titration

    International Nuclear Information System (INIS)

    Ryzhinskij, M.V.; Solntseva, L.F.

    1981-01-01

    Two procedures of potentiometric titration of about 1 mg Np are reported which are based on its oxidation to neptunium (6) with silver (2) oxide followed by titration with iron (2) to neptunium (5) in one case and to neptunium (4) in the alternative one. The error is not greater than 0.2% rel. Ten-fold uranium excess does not interfere. Up to 1% of plutonium relative to neptunium does not interfere in the case of the titration to neptunium (5). In the titration to neptunium (4), plutonium is titrated stoichiometrically [ru

  2. Determination of free acid in plutonium (IV) solutions - thermometrically, potentiometrically

    International Nuclear Information System (INIS)

    Williams, T.L.; Tucker, G.M.; Huff, G.A.; Jordan, L.G.

    1981-09-01

    The thermometric titration technique was found to offer certain advantages over potentiometry in the determination of free acid in Pu(IV) solutions. The thermometric technique was applied to the determination of free acid in plutonium nitrate solutions using potassium fluoride to suppress the hydrolytic interference of plutonium(IV). The results indicate that 0.2 to 2.0 milliequivalents of free acid can be determined with acceptable bias and precision in solutions containing up to 30 milligrams of plutonium. In contrast, neither the thermometric nor the potentiometric technique was suitable for samples containing more than eight milligrams of plutonium complexed with potassium oxalate

  3. Potentiometric study of Nd3+ chelates of substituted salicylhydroxamic acids

    International Nuclear Information System (INIS)

    Deshpande, R.G.; Jahagirdar, D.V.

    1976-01-01

    The interaction of Nd 3+ ion with salicylhydroxamic acid and 5-methyl, 5-chloro, 5-bromo, 5-nitro, 4-chloro, 4-bromo and 3-chloro salicylhydroxamic acids is investigated potentiometrically by Calvin-Bjerrum titration technique at 30 0 +- 0.1 0 and ionic strength μ=0.1 M(NaClO 4 ) in 50% v/v dioxane-water mixtures. Nd 3+ forms only 1:1 chelates with these ligands. The validity of the log K= apk + b relationship is examined for these chelates. (author)

  4. Semi-automated potentiometric titration method for uranium characterization.

    Science.gov (United States)

    Cristiano, B F G; Delgado, J U; da Silva, J W S; de Barros, P D; de Araújo, R M S; Lopes, R T

    2012-07-01

    The manual version of the potentiometric titration method has been used for certification and characterization of uranium compounds. In order to reduce the analysis time and the influence of the analyst, a semi-automatic version of the method was developed in the Brazilian Nuclear Energy Commission. The method was applied with traceability assured by using a potassium dichromate primary standard. The combined standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization. Copyright © 2011 Elsevier Ltd. All rights reserved.

  5. Redox behaviour of molybdenum in aqueous medium : a potentiometric study

    International Nuclear Information System (INIS)

    Sagi, S.R.; Mohan Rao, P.R.

    1975-01-01

    The nature of the two forms; of Mo(III) cationic-aquomolybdenum(III) (green) and anionic-chloromolybdate(III) (orange-red) has been investigated using various oxidants in hydrochloric acid mdeium, the oxidation steps being detected using a potentiometric method. The two species behave differently towards the various oxidants. The green form is a better reducing agent giving large breaks in potentials during redox titrations. The existence of the intermediate oxidation states Mosup(3.5) and Mosup(4.5) reported earlier has also been confirmed. (author)

  6. Study on the use of solid electrodes for potentiometric titrations in non-aqueous solvents-I

    International Nuclear Information System (INIS)

    Fatibello Filho, O.; Carvalho, W.M. de; Capelato, M.D.; Bulhoes, L.O.S.; Almeida Neves, E.F. de

    1984-01-01

    Fatty acids and ethanolamines were titrated potentiometrically with tetrabutylammnonium hydroxide in methyl isobutyl ketone-isopropyl alcohol and with perchloric acid in ethanol, respectively. A study of utilization of Sb, Sn, W, PbO 2 , Ti and 316L stainless steel oxides - Ag/AgBr/Bu 4 NBr (x M)/solvent electrode systems have been investigated in comparison with the glass - Ag/AgBr/Bu 4 NBr (x M)/solvent system. The best performance was obtained using W, Sb, PbO 2 and Ti electrodes have yielded a larger potential shift than glass electrode for acid-base titration. (C.L.B.) [pt

  7. Surface Complexation Modeling in Variable Charge Soils: Charge Characterization by Potentiometric Titration

    Directory of Open Access Journals (Sweden)

    Giuliano Marchi

    2015-10-01

    Full Text Available ABSTRACT Intrinsic equilibrium constants of 17 representative Brazilian Oxisols were estimated from potentiometric titration measuring the adsorption of H+ and OH− on amphoteric surfaces in suspensions of varying ionic strength. Equilibrium constants were fitted to two surface complexation models: diffuse layer and constant capacitance. The former was fitted by calculating total site concentration from curve fitting estimates and pH-extrapolation of the intrinsic equilibrium constants to the PZNPC (hand calculation, considering one and two reactive sites, and by the FITEQL software. The latter was fitted only by FITEQL, with one reactive site. Soil chemical and physical properties were correlated to the intrinsic equilibrium constants. Both surface complexation models satisfactorily fit our experimental data, but for results at low ionic strength, optimization did not converge in FITEQL. Data were incorporated in Visual MINTEQ and they provide a modeling system that can predict protonation-dissociation reactions in the soil surface under changing environmental conditions.

  8. Differential electrolytic potentiometric titration method for the determination of ciprofloxacin in drug formulations.

    Science.gov (United States)

    Abulkibash, Abdalla M; Sultan, Salah M; Al-Olyan, Abeer M; Al-Ghannam, Sheikha M

    2003-10-17

    A simple and rapid differential electrolytic potentiometric titration method for the determination of ciprofloxacin was developed. The work is based on the fast complexation reaction between iron(III) and ciprofloxacin in a ratio of 1:3, respectively, in sulfuric acid media of 0.09 mol dm(-3). Among the electrodes tested silver amalgam electrodes were found to be a suitable indicating system. By applying a current density of 0.5 muA cm(-2) to these electrodes and using iron(III) solution of 0.097 mol dm(-3) as a titrant, normal titration curves were obtained. The method was successfully applied for the determination of ciprofloxacin in drug formulations as low as 4.0 ppm.

  9. A Urea Potentiometric Biosensor Based on a Thiophene Copolymer

    Directory of Open Access Journals (Sweden)

    Cheng-Yuan (Kevin Lai

    2017-03-01

    Full Text Available A potentiometric enzyme biosensor is a convenient detector for quantification of urea concentrations in industrial processes, or for monitoring patients with diabetes, kidney damage or liver malfunction. In this work, poly(3-hexylthiophene-co-3-thiopheneacetic acid (P(3HT-co-3TAA was chemically synthesized, characterized and spin-coated onto conductive indium tin oxide (ITO glass electrodes. Urease (Urs was covalently attached to the smooth surface of this copolymer via carbodiimide coupling. The electrochemical behavior and stability of the modified Urs/P(3HT-co-3TAA/ITO glass electrode were investigated by cyclic voltammetry, and the bound enzyme activity was confirmed by spectrophotometry. Potentiometric response studies indicated that this electrode could determine the concentration of urea in aqueous solutions, with a quasi-Nernstian response up to about 5 mM. No attempt was made to optimize the response speed; full equilibration occurred after 10 min, but the half-time for response was typically <1 min.

  10. Potentiometric titration and equivalent weight of humic acid

    Science.gov (United States)

    Pommer, A.M.; Breger, I.A.

    1960-01-01

    The "acid nature" of humic acid has been controversial for many years. Some investigators claim that humic acid is a true weak acid, while others feel that its behaviour during potentiometric titration can be accounted for by colloidal adsorption of hydrogen ions. The acid character of humic acid has been reinvestigated using newly-derived relationships for the titration of weak acids with strong base. Re-interpreting the potentiometric titration data published by Thiele and Kettner in 1953, it was found that Merck humic acid behaves as a weak polyelectrolytic acid having an equivalent weight of 150, a pKa of 6.8 to 7.0, and a titration exponent of about 4.8. Interdretation of similar data pertaining to the titration of phenol-formaldehyde and pyrogallol-formaldehyde resins, considered to be analogs for humic acid by Thiele and Kettner, leads to the conclusion that it is not possible to differentiate between adsorption and acid-base reaction for these substances. ?? 1960.

  11. Semi-automated potentiometric titration method for uranium characterization

    Energy Technology Data Exchange (ETDEWEB)

    Cristiano, B.F.G., E-mail: barbara@ird.gov.br [Comissao Nacional de Energia Nuclear (CNEN), Instituto de Radioprotecao e Dosimetria (IRD), Avenida Salvador Allende s/n Recreio dos Bandeirantes, PO Box 37750, Rio de Janeiro, 22780-160 RJ (Brazil); Delgado, J.U.; Silva, J.W.S. da; Barros, P.D. de; Araujo, R.M.S. de [Comissao Nacional de Energia Nuclear (CNEN), Instituto de Radioprotecao e Dosimetria (IRD), Avenida Salvador Allende s/n Recreio dos Bandeirantes, PO Box 37750, Rio de Janeiro, 22780-160 RJ (Brazil); Lopes, R.T. [Programa de Engenharia Nuclear (PEN/COPPE), Universidade Federal do Rio de Janeiro (UFRJ), Ilha do Fundao, PO Box 68509, Rio de Janeiro, 21945-970 RJ (Brazil)

    2012-07-15

    The manual version of the potentiometric titration method has been used for certification and characterization of uranium compounds. In order to reduce the analysis time and the influence of the analyst, a semi-automatic version of the method was developed in the Brazilian Nuclear Energy Commission. The method was applied with traceability assured by using a potassium dichromate primary standard. The combined standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization. - Highlights: Black-Right-Pointing-Pointer We developed a semi-automatic version of potentiometric titration method. Black-Right-Pointing-Pointer The method is used for certification and characterization of uranium compounds. Black-Right-Pointing-Pointer The traceability of the method was assured by a K{sub 2}Cr{sub 2}O{sub 7} primary standard. Black-Right-Pointing-Pointer The results of U{sub 3}O{sub 8} reference material analyzed was consistent with certified value. Black-Right-Pointing-Pointer The uncertainty obtained, near 0.01%, is useful for characterization purposes.

  12. Moessbauer spectrometric data acquisition based on FPGA

    International Nuclear Information System (INIS)

    Zhang Yuan; Li Shimin; Chen Nan; Zhu Jingbo; Xia Yuanfu

    2008-01-01

    FPGA(Field Programmable Gate Array) is a programmable device with strong logical function and timing control ability. It is extremely potent in acquiring and processing timing signals. By replacing the traditional used SCM (Single-Chip Microcomputer) with FPGA, counting speed of Moessbauer spectrometric data acquisition can be improved markedly with significantly decreased size of the spectrometer. The counter, RAM and RS-232 communication of the module are developed on Altera Cyclone series chip EP1C6T144C8 with Quartus II. EP1C6T144C8 has 5980 logical units accompanied by 92160 bits of memory space. It is so powerful that all needs in data acquisition of the Moessbauer spectrometer can be perfectly satisfied while allowing modifications in functions and parameters. (authors)

  13. Mass Spectrometric Analysis of Synthetic Organic Pigments.

    Science.gov (United States)

    Sugaya, Naeko; Takahashi, Mitsuko; Sakurai, Katsumi; Tanaka, Nobuko; Okubo, Ichiro; Kawakami, Tsuyoshi

    2018-04-18

    Though synthetic organic colorants are used in various applications nowadays, there is the concern that impurities by-produced during the manufacturing and degradation products in some of these colorants are persistent organic pollutants and carcinogens. Thus, it is important to identify the synthetic organic colorants in various products, such as commercial paints, ink, cosmetics, food, textile, and plastics. Dyes, which are soluble in water and other solvents, could be analyzed by chromatographic methods. In contrast, it is difficult to analyze synthetic organic pigments by these methods because of their insolubility. This review is an overview of mass spectrometric analysis of synthetic organic pigments by various ionization methods. We highlight a recent study of textile samples by atmospheric pressure solid analysis probe MS. Furthermore, the mass spectral features of synthetic organic pigments and their separation from other components such as paint media and plasticizers are discussed.

  14. Effect of temperature, solvent and nature of metal cations on the potentiometric titration S of iron oxide

    International Nuclear Information System (INIS)

    Tasleem, S.; Ishrat, B.

    2008-01-01

    A comprehensive study of the potentiometric titrations of iron oxide in the presence of CU/sub 2/ and Mg/sup 2/ were under taken under different experimental conditions of temperature and concentration of metal ions in aqueous and aqueous/organic mixed solvent. The adsorption of both the metal ions were observed to increase with the increase in pH and temperature of the system. The adsorbent iron oxide preferentially adsorbs transition metal as compared to alkaline earth metal ion. (author)

  15. Potentiometric-level monitoring program: Mississippi and Louisiana. Annual status report for fiscal year 1984

    International Nuclear Information System (INIS)

    1986-07-01

    Potentiometric-level data presented in this report were collected from October 1983 through September 1984 at 79 wells in Mississippi and Louisiana. These wells are located near Richton and Cypress Creek Domes in Mississippi and Vacherie Dome in Louisiana. Fourteen wells were added to the program during this period. Two of these wells were not measurable. Two wells previously unmeasurable were located and measured. One well was destroyed during military maneuvers in the area. Analysis of the data indicated minimal, if any, change in potentiometric levels during the past year in the Citronelle, Hattiesburg, Cockfield, Sparta, and Wilcox Formations in Mississippi. A continuing decline in potentiometric levels, ranging from 0.3 to 0.6 foot per year, occurred in the wells screened in the caprock at Richton and Cypress Creek Domes. The Catahoula Formation experienced a continuing decline in potentiometric levels of about 2 feet per year. Two wells in the Cook Mountain Formation showed a continuing rise in potentiometric levels ranging from 8 to 30 ft during the past fiscal year. Wells screened in the Austin Formation in Louisiana showed a fall in potentiometric levels of 2 to 3 ft over the past fiscal year. Other formations in Louisiana generally showed no change in potentiometric levels over the past year. 26 refs., 2 figs., 3 tabs

  16. Energy dispersive X-Ray fluorescence spectrometric study of ...

    African Journals Online (AJOL)

    Energy dispersive X-Ray fluorescence spectrometric study of compositional differences in trace elements in dried Moringa oleifera leaves grown in two different agro-ecological locations in Ebonyi State, Nigeria.

  17. Gas Chromatography-Mass Spectrometric Analysis and Insecticidal ...

    African Journals Online (AJOL)

    HP

    Original Research Article. Gas Chromatography-Mass Spectrometric Analysis and ... into a natural fumigant/insecticide for the control of stored product insects. Keywords: Mallotus ..... stability as well as reduce cost. ACKNOWLEDGEMENT.

  18. Gas Chromatography-Mass Spectrometric Analysis of Nematicidal ...

    African Journals Online (AJOL)

    Gas Chromatography-Mass Spectrometric Analysis of Nematicidal Essential Oil of Valeriana ... Tropical Journal of Pharmaceutical Research ... have a potential to be developed to natural nematicides for the control of cereal cyst nematodes.

  19. Gas Chromatography-Mass Spectrometric Analysis and Insecticidal ...

    African Journals Online (AJOL)

    Tropical Journal of Pharmaceutical Research ... apelta aerial parts was analyzed by gas chromatography/mass spectrometric (GC/MS) to determine its composition. ... into a natural fumigant/insecticide for the control of stored product insects.

  20. Carbon Nanotubes-Based Potentiometric Bio-Sensors for Determination of Urea

    Directory of Open Access Journals (Sweden)

    Ewa Jaworska

    2015-07-01

    Full Text Available The possibility of using disposable plastic-carbon potentiometric sensors as enzyme biosensors was examined. Urease enzyme was immobilized on poly(vinyl chloride based H+- or NH4+-selective membranes using cellulose acetate. This approach has resulted in a potentiometric response on changing the pH of the solution or NH4+ ion content due to an enzymatic reaction that occurs between urease and urea. Both types of potentiometric biosensors for urea were characterized by good analytical parameters as high sensitivity and fast response time.

  1. Chemical sensors and the development of potentiometric methods for liquid media analysis

    International Nuclear Information System (INIS)

    Vlasov, Yu.G.; Kolodnikov, V.V.; Ermolenko, Yu.E.; Mikhajlova, S.S.

    1996-01-01

    Aspects of applying indirect potentiometric determination to chemical analysis are considered. Among them are the standard and modified addition and subtraction methods, the multiple addition method, and potentiometric titration using ion-selective electrodes as indicators. These methods significantly extend the capabilities of ion-selective potentiometric analysis. Conditions for the applicability of the above-mentioned methods to various samples (Cd, REE, Th, iodides and others) are discussed using all available ion-selective electrodes as examples. 162 refs., 2 figs., 5 tabs

  2. Gas chromatography of organic microcontaminants using atomic emission and mass spectrometric detection combined in one instrument (GC-AED/MS)

    NARCIS (Netherlands)

    Mol, H.G.J.; Hankemeier, T.; Brinkman, U.A.T.

    1999-01-01

    This study describes the coupling of an atomic-emission detector and mass-spectrometric detector to a single gas chromatograph. Splitting of the column effluent enables simultaneous detection by atomic-emission detection (AED) and mass spectrometry (MS) and yields a powerful system for the target

  3. Potentiometric Surfaces in the Springfield Plateau and Ozark Aquifers of Northwestern Arkansas, Southeastern Kansas, Southwestern Missouri, and Northeastern Oklahoma, 2006

    Science.gov (United States)

    Gillip, Jonathan A.; Czarnecki, John B.; Mugel, Douglas N.

    2008-01-01

    The Springfield Plateau and Ozark aquifers are important sources of ground water in the Ozark Plateaus aquifer system. Water from these aquifers is used for agricultural, domestic, industrial, and municipal water sources. Changing water use over time in these aquifers presents a need for updated potentiometric-surface maps of the Springfield Plateau and Ozark aquifers. The Springfield Plateau aquifer consists of water-bearing Mississippian-age limestone and chert. The Ozark aquifer consists of Late Cambrian to Middle Devonian age water-bearing rocks consisting of dolostone, limestone, and sandstone. Both aquifers are complex with areally varying lithologies, discrete hydrologic units, varying permeabilities, and secondary permeabilities related to fractures and karst features. During the spring of 2006, ground-water levels were measured in 285 wells. These data, and water levels from selected lakes, rivers, and springs, were used to create potentiometric-surface maps for the Springfield Plateau and Ozark aquifers. Linear kriging was used initially to construct the water-level contours on the maps; the contours were subsequently modified using hydrologic judgment. The potentiometric-surface maps presented in this report represent ground-water conditions during the spring of 2006. During the spring of 2006, the region received less than average rainfall. Dry conditions prior to the spring of 2006 could have contributed to the observed water levels as well. The potentiometric-surface map of the Springfield Plateau aquifer shows a maximum measured water-level altitude within the study area of about 1,450 feet at a spring in Barry County, Missouri, and a minimum measured water-level altitude of 579 feet at a well in Ottawa County, Oklahoma. Cones of depression occur in Dade, Lawrence and Newton Counties in Missouri and Delaware and Ottawa Counties in Oklahoma. These cones of depression are associated with private wells. Ground water in the Springfield Plateau aquifer

  4. Status of mass spectrometric radiocarbon detection at ETHZ

    Energy Technology Data Exchange (ETDEWEB)

    Seiler, Martin; Maxeiner, Sascha; Wacker, Lukas; Synal, Hans-Arno

    2015-10-15

    A prototype of a mass spectrometric radiocarbon detection instrument without accelerator stage was built for the first time and set into operation at ETH Zurich. The system is designed as an experimental platform to optimize performance of {sup 14}C detection at low ion energies and to study the most relevant processes that may limit system performance. The optimized stripper unit incorporates differential pumping to maintain a low gas outflow and a revised tube design to better match the phase space volume of the ion beam at low energies. The system is fully operational and has demonstrated true radiocarbon dating capabilities. The overall beam transmission through the stripper tube is about 40% for the 1{sup +} charge state. Radiocarbon analyses with an overall precision of 0.6% were obtained on a single sample under regular measurement conditions. By analyzing multiple targets of the same sample material an uncertainty level of 0.3% has been reached. The background level corresponds to a radiocarbon age of 40,000 years.

  5. Potentiometric titration of free acid in uranium solutions

    International Nuclear Information System (INIS)

    Suh, M. Y.; Kim, W. H.; Kim, J. S.; Sohn, S. C.; Eom, T. Y.; Lee, C. H.; Jeon, Y. S.; Han, S. H.

    1998-02-01

    Hydrolysis properties of metal cations and fundamental principles of the potentiometric titration of free acid in aqueous solutions containing metal cations were described. The published papers and reports for the alkalimetric and acidimetric titration of free acid were surveyed, and the applicability of these titration methods to the uranium and/or plutonium solutions were discussed. This technical report also includes the various results obtained from the authors' researches to establish the alkalimetric and acidimetric titration methods for the determination of free acid in nitric acid solutions containing uranium and/or oxalic acid, and aluminum. The procedure manuals used in chemical processes and the newly prepared manuals based on the authors' researches are appended. (author). 26 refs., 54 figs

  6. Potentiometric titration of free acid in uranium solutions

    Energy Technology Data Exchange (ETDEWEB)

    Suh, M. Y.; Kim, W. H.; Kim, J. S.; Sohn, S. C.; Eom, T. Y.; Lee, C. H.; Jeon, Y. S.; Han, S. H.

    1998-02-01

    Hydrolysis properties of metal cations and fundamental principles of the potentiometric titration of free acid in aqueous solutions containing metal cations were described. The published papers and reports for the alkalimetric and acidimetric titration of free acid were surveyed, and the applicability of these titration methods to the uranium and/or plutonium solutions were discussed. This technical report also includes the various results obtained from the authors` researches to establish the alkalimetric and acidimetric titration methods for the determination of free acid in nitric acid solutions containing uranium and/or oxalic acid, and aluminum. The procedure manuals used in chemical processes and the newly prepared manuals based on the authors` researches are appended. (author). 26 refs., 54 figs.

  7. An accurate potentiometric titration of 5-25 mg uranium

    International Nuclear Information System (INIS)

    Slanina, J.; Bakker, F.; Lingerak, W.A.

    1976-01-01

    A potentiometric titration of 5 to 25 mg uranium is described. Sulphamic and phosphoric acid are added to the sample (volume 1 ml), U VI is reduced to U IV by Fe 2+ and the excess of Fe 2+ is oxidized by a mixture of nitric acid, sulphamic acid and ammonium molybdate; vanadyl sulphate is added to ensure a sharp end-point of the titration. The resultant U IV is titrated automatically with 0.02500N potassiumdichromate using a platinum indicator electrode. The automatic titration is performed both with a commercial titrator (Mettler) and with an R.C.N. titrator which waits after each addition until the equilibrium is reached. Using the Mettler titrator an accuracy of 0.05% relative was reached. The R.C.N. setpoint titrator gave results with an accuracy of 0.04% relative at the 20-mg U level. Each titration takes 5 to 7 min. (author)

  8. Application of cause-and-effect analysis to potentiometric titration.

    Science.gov (United States)

    Kufelnicki, A; Lis, S; Meinrath, G

    2005-08-01

    A first attempt has been made to interpret physicochemical data from potentiometric titration analysis in accordance with the complete measurement-uncertainty budget approach (bottom-up) of ISO and Eurachem. A cause-and-effect diagram is established and discussed. Titration data for arsenazo III are used as a basis for this discussion. The commercial software Superquad is used and applied within a computer-intensive resampling framework. The cause-and-effect diagram is applied to evaluation of seven protonation constants of arsenazo III in the pH range 2-10.7. The data interpretation is based on empirical probability distributions and their analysis by second-order correct confidence estimates. The evaluated data are applied in the calculation of a speciation diagram including uncertainty estimates using the probabilistic speciation software Ljungskile.

  9. Limitations of potentiometric oxygen sensors operating at low oxygen levels

    DEFF Research Database (Denmark)

    Lund, Anders; Jacobsen, Torben; Hansen, Karin Vels

    2011-01-01

    The electrochemical processes that limit the range of oxygen partial pressures in which potentiometric oxygen sensors can be used, were analysed using a theoretical and an experimental approach. Electrochemical impedance spectroscopy was performed on porous Pt/yttria stabilised zirconia (YSZ......) electrodes between 10−6 and 0.2 bar and at temperatures between 500 and 950 °C. The flow of oxide ions and electron holes through a sensor cell, with a YSZ electrolyte, were calculated under similar conditions. The oxygen permeation of the sensor cell was insignificant at an oxygen partial pressure of 10......−6 bar for an inlet flow rate higher than 2 L h−1 between 600 and 800 °C. The polarisation resistance measured between 10−6 and 10−4 bar was found to be inversely proportional to the oxygen partial pressure, nearly temperature independent and inversely proportional to the inlet gas flow rate, which shows...

  10. Determination of uranium and plutonium by sequential potentiometric titration

    International Nuclear Information System (INIS)

    Kato, Yoshiharu; Takahashi, Masao

    1976-01-01

    The determination of uranium and plutonium in mixed oxide fuels has been developed by sequential potentiometric titration. A weighed sample of uranium and plutonium oxides is dissolved in a mixture of nitric and hydrofluoric acids and the solution is fumed with sulfuric acid. After the reduction of uranium and plutonium to uranium(IV) and plutonium(III) by chromium(II) sulfate, 5 ml of buffer solution (KCl-HCl, pH 1.0) is added to the solution. Then the solution is diluted to 30 ml with water and the pH of the solution is adjusted to 1.0 -- 1.5 with 1 M sodium hydroxide. The solution is stirred until the oxidation of the excess of chromium(II) by air is completed. After the removal of dissolved oxygen by bubbling nitrogen through the solution for 10 minutes, uranium (IV) is titrated with 0.1 N cerium(IV) sulfate. Then, plutonium is titrated by 0.02 N cerium(IV) sulfate. When a mixture of uranium and plutonium is titrated with 0.1 N potassium dichromate potentiometrically, the potential change at the end point of plutonium is very small and the end point of uranium is also unclear when 0.1 N potassium permanganate is used as a titrant. In the present method, nitrate, fluoride and copper(II) interfere with the determination of plutonium and uranium. Iron interferes quantitatively with the determination of plutonium but not of uranium. Results obtained in applying the proposed method to 50 mg of mixtures of plutonium and uranium ((7.5 -- 50))% Pu were accurate to within 0.15 mg of each element. (auth.)

  11. Structure, equilibrium and ligand exchange dynamics in the binary and ternary dioxouranium(VI)-ethylenediamine-N,N'-diacetic acid-fluoride system: A potentiometric, NMR and X-ray crystallographic study.

    Science.gov (United States)

    Palladino, Giuseppe; Szabó, Zoltán; Fischer, Andreas; Grenthe, Ingmar

    2006-11-21

    The structure, thermodynamics and kinetics of the binary and ternary uranium(VI)-ethylenediamine-N,N'-diacetate (in the following denoted EDDA) fluoride systems have been studied using potentiometry, 1H, 19F NMR spectroscopy and X-ray diffraction. The UO2(2+)-EDDA system could be studied up to -log[H3O+] = 3.4 where the formation of two binary complexes UO2(EDDA)(aq) and UO2(H3EDDA)3+ were identified, with equilibrium constants logbeta(UO2EDDA) = 11.63 +/- 0.02 and logbeta(UO2H3EDDA3+) = 1.77 +/- 0.04, respectively. In the ternary system the complexes UO2(EDDA)F-, UO2(EDDA)(OH)- and (UO2)2(mu-OH)2(HEDDA)2F2(aq) were identified; the latter through 19F NMR. 1H NMR spectra indicate that the EDDA ligand is chelate bonded in UO2(EDDA)(aq), UO2(EDDA)F- and UO2(EDDA)(OH)- while only one carboxylate group is coordinated in UO2(H3EDDA)3+. The rate and mechanism of the fluoride exchange between UO2(EDDA)F- and free fluoride was studied by 19F NMR spectroscopy. Three reactions contribute to the exchange; (i) site exchange between UO2(EDDA)F- and free fluoride without any net chemical exchange, (ii) replacement of the coordinated fluoride with OH- and (iii) the self dissociation of the coordinated fluoride forming UO2(EDDA)(aq); these reactions seem to follow associative mechanisms. (1)H NMR spectra show that the exchange between the free and chelate bonded EDDA is slow and consists of several steps, protonation/deprotonation and chelate ring opening/ring closure, the mechanism cannot be elucidated from the available data. The structure (UO2)2(EDDA)2(mu-H2EDDA) was determined by single crystal X-ray diffraction and contains two UO2(EDDA) units with tetracoordinated EDDA linked by H2EDDA in the "zwitterion" form, coordinated through a single carboxylate oxygen from each end to the two uranium atoms. The geometry of the complexes indicates that there is no geometric constraint for an associative ligand substitution mechanism.

  12. Determination of uranium and plutonium in PFBR MOX fuel using automatic potentiometric titrator

    International Nuclear Information System (INIS)

    Kelkar, Anoop; Meena, D.L.; Singh, Mamta; Kapoor, Y.S.; Pabale, Sagar; Fulzele, Ajit; Das, D.K.; Behere, P.G.; Afzal, Mohd

    2014-01-01

    Present paper describes the automatic potentiometric method for the determination of uranium and plutonium in less complexing H 2 SO 4 with scaling down the reagent volumes 15-20 ml in order to minimize the waste generation

  13. Comparison of Potentiometric and Gravimetric Methods for Determination of O/U Ratio

    International Nuclear Information System (INIS)

    Farida; Windaryati, L; Putro Kasino, P

    1998-01-01

    Comparison of determination O/U ratio by using potentiometric and gravimetric methods has been done. Those methods are simple, economical and having high precision and accuracy. Determination O/U ratio for UO 2 powder using potentiometric is carried out by adopting the davies-gray method. This technique is based on the redox reaction of uranium species such as U(IV) and U(VI). In gravimetric method,the UO 2 power as a sample is calcined at temperature of 900 C, and the weight of the sample is measured after calcination process. The t-student test show that there are no different result significantly between those methods. However, for low concentration in the sample the potentiometric method has a highed precision and accuracy compare to the gravimetric method. O/U ratio obtained is 2.00768 ± 0,00170 for potentiometric method 2.01089 ± 0,02395 for gravimetric method

  14. Potentiometric titration of zinc and cadmium in electrolytes of in galvanic baths

    International Nuclear Information System (INIS)

    Kosyuga, E.A.; Kalugin, A.A.; Gur'ev, I.A.

    1979-01-01

    The method of potentiometric titration of zinc and cadmium by complexone 3 in electrolytes of galvanic baths using sulphide - silver electrode for determining the finite point of titration is suggested. Copper (2) ions are proposed as indicator ions. The potentiometric determination should be performed at pH=10. The method is verified on model electrolyte solutions and on the electrolyte solutions of operating baths.The technique can be used for automatic control. The time for analysis is 10 minutes

  15. Potentiometric determination of uranium with cobalt (3) acetate as oxidimetric titrant

    International Nuclear Information System (INIS)

    Muhammad, H.; Ishrat, P.; Zyka, J.

    1972-01-01

    A potentiometric method for the determination of uranium through the reduction of hexavalent to tetravalent state and its potentiometric oxidation in 8 N sulphuric acid with standard cobalt (3)-acetate has been worked out. The method is quite accurate with the error not exceeding 1% for mg amounts. Moreover an apparatus for preservation of reduced solution of uranium and its delivery for titrations has been designed. The same apparatus can be used for reducing and preserving solutions of strong reducing titrants. (author)

  16. Determination of quaternary ammonium compounds by potentiometric titration with an ionic surfactant electrode: single-laboratory validation.

    Science.gov (United States)

    Price, Randi; Wan, Ping

    2010-01-01

    A potentiometric titration for determining the quaternary ammonium compounds (QAC) commonly found in antimicrobial products was validated by a single laboratory. Traditionally, QACs were determined by using a biphasic (chloroform and water) manual titration procedure. Because of safety considerations regarding chloroform, as well as the subjectivity of color indicator-based manual titration determinations, an automatic potentiometric titration procedure was tested with quaternary nitrogen product formulations. By using the Metrohm Titrando system coupled with an ionic surfactant electrode and an Ag/AgCl reference electrode, titrations were performed with various QAC-containing formulation products/matrixes; a standard sodium lauryl sulfate solution was used as the titrant. Results for the products tested are sufficiently reproducible and accurate for the purpose of regulatory product enforcement. The robustness of the method was measured by varying pH levels, as well as by comparing buffered versus unbuffered titration systems. A quantitation range of 1-1000 ppm quaternary nitrogen was established. Eight commercially available antimicrobial products covering a variety of matrixes were assayed; the results obtained were comparable to those obtained by the manual titration method. Recoveries of 94 to 104% were obtained for spiked samples.

  17. Mass Spectrometric C-14 Detection Techniques: Progress Report

    Science.gov (United States)

    Synal, H.

    2013-12-01

    Accelerator Mass Spectrometry (AMS) has been established as the best-suited radiocarbon detection technique. In the past years, significant progress with AMS instrumentation has been made resulting in a boom of new AMS facilities around the World. Today, carbon only AMS systems predominantly utilize 1+ charge state and molecule destruction in multiple ion gas collisions in stripper gas cell. This has made possible a significant simplification of the instruments, a reduction of ion energies and related to this less required space of the installations. However, state-of-the-art AMS instruments have still not reached a development stage where they can be regarded as table-top systems. In this respect, more development is needed to further advance the applicability of radiocarbon not only in the traditional fields of dating but also in biomedical research and new fields in Earth and environmental sciences. In a the proof-of-principle experiment the feasibility of radiocarbon detection over the entire range of dating applications was demonstrated using a pure mass spectrometer and ion energies below 50 keV. Now an experimental platform has been completed to test performance and to explore operation and measurement conditions of pure mass spectrometric radiocarbon detection. This contribution will overview the physical principles, which make this development possible and discuss key parameters of the instrumental design and performance of such an instrument.

  18. Integrated, paper-based potentiometric electronic tongue for the analysis of beer and wine

    International Nuclear Information System (INIS)

    Nery, Emilia Witkowska; Kubota, Lauro T.

    2016-01-01

    The following manuscript details the stages of construction of a novel paper-based electronic tongue with an integrated Ag/AgCl reference, which can operate using a minimal amount of sample (40 μL). First, we optimized the fabrication procedure of silver electrodes, testing a set of different methodologies (electroless plating, use of silver nanoparticles and commercial silver paints). Later a novel, integrated electronic tongue system was assembled with the use of readily available materials such as paper, wax, lamination sheets, bleach etc. New system was thoroughly characterized and the ion-selective potentiometric sensors presented performance close to theoretical. An electronic tongue, composed of electrodes sensitive to sodium, calcium, ammonia and a cross-sensitive, anion-selective electrode was used to analyze 34 beer samples (12 types, 19 brands). This system was able to discriminate beers from different brands, and types, indicate presence of stabilizers and antioxidants, dyes or even unmalted cereals and carbohydrates added to the fermentation wort. Samples could be classified by type of fermentation (low, high) and system was able to predict pH and in part also alcohol content of tested beers. In the next step sample volume was minimalized by the use of paper sample pads and measurement in flow conditions. In order to test the impact of this advancement a four electrode system, with cross-sensitive (anion-selective, cation-selective, Ca"2"+/Mg"2"+, K"+/Na"+) electrodes was applied for the analysis of 11 types of wine (4 types of grapes, red/white, 3 countries). Proposed matrix was able to group wines produced from different varieties of grapes (Chardonnay, Americanas, Malbec, Merlot) using only 40 μL of sample. Apart from that, storage stability studies were performed using a multimeter, therefore showing that not only fabrication but also detection can be accomplished by means of off-the-shelf components. This manuscript not only describes new

  19. Integrated, paper-based potentiometric electronic tongue for the analysis of beer and wine.

    Science.gov (United States)

    Nery, Emilia Witkowska; Kubota, Lauro T

    2016-04-28

    The following manuscript details the stages of construction of a novel paper-based electronic tongue with an integrated Ag/AgCl reference, which can operate using a minimal amount of sample (40 μL). First, we optimized the fabrication procedure of silver electrodes, testing a set of different methodologies (electroless plating, use of silver nanoparticles and commercial silver paints). Later a novel, integrated electronic tongue system was assembled with the use of readily available materials such as paper, wax, lamination sheets, bleach etc. New system was thoroughly characterized and the ion-selective potentiometric sensors presented performance close to theoretical. An electronic tongue, composed of electrodes sensitive to sodium, calcium, ammonia and a cross-sensitive, anion-selective electrode was used to analyze 34 beer samples (12 types, 19 brands). This system was able to discriminate beers from different brands, and types, indicate presence of stabilizers and antioxidants, dyes or even unmalted cereals and carbohydrates added to the fermentation wort. Samples could be classified by type of fermentation (low, high) and system was able to predict pH and in part also alcohol content of tested beers. In the next step sample volume was minimalized by the use of paper sample pads and measurement in flow conditions. In order to test the impact of this advancement a four electrode system, with cross-sensitive (anion-selective, cation-selective, Ca(2+)/Mg(2+), K(+)/Na(+)) electrodes was applied for the analysis of 11 types of wine (4 types of grapes, red/white, 3 countries). Proposed matrix was able to group wines produced from different varieties of grapes (Chardonnay, Americanas, Malbec, Merlot) using only 40 μL of sample. Apart from that, storage stability studies were performed using a multimeter, therefore showing that not only fabrication but also detection can be accomplished by means of off-the-shelf components. This manuscript not only describes new

  20. Integrated, paper-based potentiometric electronic tongue for the analysis of beer and wine

    Energy Technology Data Exchange (ETDEWEB)

    Nery, Emilia Witkowska, E-mail: ewitkowskanery@ichf.edu.pl [Department of Analytical Chemistry, Institute of Chemistry – UNICAMP, P.O. Box 6154, 13084-971 Campinas, SP (Brazil); National Institute of Science and Technology in Bioanalytics, Institute of Chemistry – UNICAMP, P.O. Box 6154, Campinas (Brazil); Kubota, Lauro T. [Department of Analytical Chemistry, Institute of Chemistry – UNICAMP, P.O. Box 6154, 13084-971 Campinas, SP (Brazil); National Institute of Science and Technology in Bioanalytics, Institute of Chemistry – UNICAMP, P.O. Box 6154, Campinas (Brazil)

    2016-04-28

    The following manuscript details the stages of construction of a novel paper-based electronic tongue with an integrated Ag/AgCl reference, which can operate using a minimal amount of sample (40 μL). First, we optimized the fabrication procedure of silver electrodes, testing a set of different methodologies (electroless plating, use of silver nanoparticles and commercial silver paints). Later a novel, integrated electronic tongue system was assembled with the use of readily available materials such as paper, wax, lamination sheets, bleach etc. New system was thoroughly characterized and the ion-selective potentiometric sensors presented performance close to theoretical. An electronic tongue, composed of electrodes sensitive to sodium, calcium, ammonia and a cross-sensitive, anion-selective electrode was used to analyze 34 beer samples (12 types, 19 brands). This system was able to discriminate beers from different brands, and types, indicate presence of stabilizers and antioxidants, dyes or even unmalted cereals and carbohydrates added to the fermentation wort. Samples could be classified by type of fermentation (low, high) and system was able to predict pH and in part also alcohol content of tested beers. In the next step sample volume was minimalized by the use of paper sample pads and measurement in flow conditions. In order to test the impact of this advancement a four electrode system, with cross-sensitive (anion-selective, cation-selective, Ca{sup 2+}/Mg{sup 2+}, K{sup +}/Na{sup +}) electrodes was applied for the analysis of 11 types of wine (4 types of grapes, red/white, 3 countries). Proposed matrix was able to group wines produced from different varieties of grapes (Chardonnay, Americanas, Malbec, Merlot) using only 40 μL of sample. Apart from that, storage stability studies were performed using a multimeter, therefore showing that not only fabrication but also detection can be accomplished by means of off-the-shelf components. This manuscript not only

  1. Evaluation of the performance of a metrohm titrator titrando-836 in potentiometric analysis of uranium for safeguards purposes

    International Nuclear Information System (INIS)

    Cristiano, Barbara Fernandes; Silva, Jose Wanderley S. da; Barros, Pedro Dionisio de; Araujo, Radier Mario S. de

    2009-01-01

    To achieve the requirements of the Brazilian State System of Accounting for and Control of Nuclear Materials - SSAC the Safeguards Laboratory of Brazilian Nuclear Energy Commission, LASAL, has been applying the 'Davies and Gray/NBL' method for Potentiometric determination of total uranium concentration in several forms of nuclear materials since 1984. To improve the accuracy and the repeatability the method uses as titrant, standard reference potassium dichromate NIST SRM 136e and the results are also corrected for bias with NBL CRM 112A uranium metal assay standard. This work describes the assays performed for validation of a Metrohm 836 potentiometric titrator acquired by LASAL in order to improve the analytical methodology of the laboratory. The titrator is attached to a Pt:Rh (90:10) as indicator electrode and a mercurous sulfate as the reference electrode. The evaluation of accuracy and repeatability were made by comparison, the results provided by the titrator with the certified value of standards and also by the participation in round robin program sponsored by New Brunswick Laboratory - NBL. The validation was done by a comparison of the performance between the Metrohm 836 and a Mettler - DL67 titrator which has currently been used by the laboratory. It included evaluation of the results of both equipment, the repeatability of the measurement, any systematic contributions and its uncertainties. (author)

  2. Development of gallium arsenide gamma spectrometric detector

    International Nuclear Information System (INIS)

    Kobayashi, T.; Kuru, I.

    1975-03-01

    GaAs semiconductor material has been considered to be a suitable material for gamma-ray spectrometer operating at room temperature since it has a wid-band gap, larger than that of silicon and germanium. The basic objective of this work is to develop a GaAs gamma-ray spectrometric detector which could be used for gamma spectrometric measurement of uranium and plutonium in nuclear fuel safeguards. Liquid phase epitaxial techniques using iron (Fe) as dopant have been developed in making high purity GaAs crystals suitable for gamma-ray spectrometer operating at room temperature. Concentration of Fe in the epitaxial crystal was controlled by initial growth temperature. The best quality epitaxial crystal was obtained under the following conditions: starting temperature is about 800degC, the proportion of Fe to Ga solvent is 1 to 300. Carrier concentration of epitaxial crystals grown distributed in the ranges of 10 12 cm -3 to 10 14 cm -3 at room temperature. The thickness of the crystals ranged from 38 μm to 120 μm. Au-GaAs surface barrier detector was made of epitaxial crystal. Some of the detector were encapsulated in a can with a 50 μm Be window by welding a can to the detector holder. The detector with high energy resolution and good charge collecting characteristics was selected by alpha spectrometry at room temperature. Energy resolution of the detector for gamma-rays up to about 200 keV was very good at room temperature operation. The best energy resolutions taken with a GaAs detector were 3 keV (fwhm) and 3.8 keV for 241 Am 59.6 keV and 57 Co 122 keV, respectively, at room temperature. In order to study the applicability of the detector for nuclear safeguards, the measurements of 235 U gamma-ray spectrum have been carried out at room temperature. It was clarified that the gamma-ray spectrum of enriched U sample could be measured in high resolution with GaAs detector at room temperature, and that the content of 235 U in enriched U sources could be determined by

  3. Potentiometric surface of the Upper Floridan aquifer in the St. Johns River water management district and vicinity, Florida, September 2005

    Science.gov (United States)

    Kinnaman, Sandra L.

    2006-01-01

    This map depicts the potentiometric surface of the Upper Floridan aquifer in the St. Johns River Water Management District and vicinity for September 2005. Potentiometric contours are based on water-level measurements collected at 643 wells during the period September 12-28, near the end of the wet season. Some contours are inferred from previous potentiometric-surface maps with larger well networks. The potentiometric surface of the carbonate Upper Floridan aquifer responds mainly to rainfall, and more locally, to ground-water withdrawals and springflow. Potentiometric-surface highs generally correspond to topographic highs where the aquifer is recharged. Springs and areas of diffuse upward leakage naturally discharge water from the aquifer and are most prevalent along the St. Johns River. Areas of discharge are reflected by depressions in the potentiometric surface. Ground-water withdrawals locally have lowered the potentiometric surface. Ground water in the Upper Floridan aquifer generally flows from potentiometric highs to potentiometric lows in a direction perpendicular to the contours.

  4. Potentiometric Surface of the Upper Floridan Aquifer in the St. Johns River Water Management District and Vicinity, Florida, September 2008

    Science.gov (United States)

    Kinnaman, Sandra L.; Dixon, Joann F.

    2009-01-01

    This map depicts the potentiometric surface of the Upper Floridan aquifer in the St. Johns River Water Management District and vicinity for September 2008. Potentiometric contours are based on water-level measurements collected at 589 wells during the period September 15-25, near the end of the wet season. Some contours are inferred from previous potentiometric-surface maps with larger well networks. The potentiometric surface of the carbonate Upper Floridan aquifer responds mainly to rainfall, and more locally, to ground-water withdrawals and spring flow. Potentiometric-surface highs generally correspond to topographic highs where the aquifer is recharged. Springs and areas of diffuse upward leakage naturally discharge water from the aquifer and are most prevalent along the St. Johns River. Areas of discharge are reflected by depressions in the potentiometric surface. Ground-water withdrawals locally have lowered the potentiometric surface. Ground water in the Upper Floridan aquifer generally flows from potentiometric highs to potentiometric lows in a direction perpendicular to the contours.

  5. Potentiometric Surface of the Upper Floridan Aquifer in the St. Johns River Water Management District and Vicinity, Florida, September 2007

    Science.gov (United States)

    Kinnaman, Sandra L.; Dixon, Joann F.

    2008-01-01

    This map depicts the potentiometric surface of the Upper Floridan aquifer in the St. Johns River Water Management District and vicinity for September 2007. Potentiometric contours are based on water-level measurements collected at 554 wells during the period September 15-27, near the end of the wet season. Some contours are inferred from previous potentiometric-surface maps with larger well networks. The potentiometric surface of the carbonate Upper Floridan aquifer responds mainly to rainfall, and more locally, to ground-water withdrawals and spring flow. Potentiometric-surface highs generally correspond to topographic highs where the aquifer is recharged. Springs and areas of diffuse upward leakage naturally discharge water from the aquifer and are most prevalent along the St. Johns River. Areas of discharge are reflected by depressions in the potentiometric surface. Ground-water withdrawals locally have lowered the potentiometric surface. Ground water in the Upper Floridan aquifer generally flows from potentiometric highs to potentiometric lows in a direction perpendicular to the contours.

  6. Potentiometric surface of the upper Floridan Aquifer in the St. Johns River Water Management District and vicinity, Florida, September, 2004

    Science.gov (United States)

    Kinnaman, Sandra L.

    2005-01-01

    Introduction: This map depicts the potentiometric surface of the Upper Floridan aquifer in the St. Johns River Water Management District and vicinity in September 2004. Potentiometric contours are based on water-level measurements collected at 608 wells during the period September 14-October 1, near the end of the wet season. The shapes of some contours have been inferred from previous potentiometric-surface maps with larger well networks. The potentiometric surface of the carbonate Upper Floridan aquifer responds mainly to rainfall, and more locally, to ground-water withdrawals. Potentiometric-surface highs generally correspond to topographic highs where the aquifer is recharged. Springs and areas of diffuse upward leakage naturally discharge water from the aquifer and are most prevalent along the St. Johns River. Areas of discharge are reflected by depressions in the potentiometric surface. Ground-water withdrawals locally have lowered the potentiometric surface. Ground water in the Upper Floridan aquifer generally flows from potentiometric highs to potentiometric lows in a direction perpendicular to the contours.

  7. Potentiometric Surface of the Upper Floridan Aquifer in the St. Johns River Water Management District and Vicinity, Florida, May, 2004

    Science.gov (United States)

    Kinnaman, Sandra L.; Knowles, Leel

    2004-01-01

    INTRODUCTION This map depicts the potentiometric surface of the Upper Floridan aquifer in the St. Johns River Water Management District and vicinity in May 2001. Potentiometric contours are based on water-level measurements collected at 684 wells during the period May 2 - 30, near the end of the dry season. The shapes of some contours have been inferred from previous potentiometric-surface maps with larger well networks. The potentiometric surface of the carbonate Upper Floridan aquifer responds mainly to rainfall, and more locally, to ground-water withdrawals. Potentiometric-surface highs generally correspond to topographic highs where the aquifer is recharged. Springs and areas of diffuse upward leakage naturally discharge water from the aquifer and are most prevalent along the St. Johns River. Areas of discharge are reflected by depressions in the potentiometric surface. Ground-water withdrawals locally have lowered the potentiometric surface. Ground water in the Upper Floridan aquifer generally flows from potentiometric highs to potentiometric lows in a direction perpendicular to the contours.

  8. Potentiometric Surface of the Upper Floridan Aquifer in the St. Johns River Water Management District and Vicinity, Florida, May 2006

    Science.gov (United States)

    Kinnaman, Sandra L.

    2006-01-01

    Introduction: This map depicts the potentiometric surface of the Upper Floridan aquifer in the St. Johns River Water Management District and vicinity for May 2006. Potentiometric contours are based on water-level measurements collected at 599 wells during the period May 14-31, near the end of the dry season. Some contours are inferred from previous potentiometric-surface maps with larger well networks. The potentiometric surface of the carbonate Upper Floridan aquifer responds mainly to rainfall, and more locally, to ground-water withdrawals and springflow. Potentiometric-surface highs generally correspond to topographic highs where the aquifer is recharged. Springs and areas of diffuse upward leakage naturally discharge water from the aquifer and are most prevalent along the St. Johns River. Areas of discharge are reflected by depressions in the potentiometric surface. Ground-water withdrawals locally have lowered the potentiometric surface. Ground water in the Upper Floridan aquifer generally flows from potentiometric highs to potentiometric lows in a direction perpendicular to the contours.

  9. Potentiometric Surface of the Upper Floridan Aquifer in the St. Johns River Water Management District and Vicinity, Florida, May 2007

    Science.gov (United States)

    Kinnaman, Sandra L.; Dixon, Joann F.

    2007-01-01

    Introduction This map depicts the potentiometric surface of the Upper Floridan aquifer in the St. Johns River Water Management District and vicinity for May 2007. Potentiometric contours are based on water-level measurements collected at 566 wells during the period May 4-June 11 near the end of the dry season, however most of the water level data for this map were collected by the U.S. Geological Survey during the period May 21-25, 2007. Some contours are inferred from previous potentiometric-surface maps with larger well networks. The potentiometric surface of the carbonate Upper Floridan aquifer responds mainly to rainfall, and more locally, to ground-water withdrawals and spring flow. Potentiometric-surface highs generally correspond to topographic highs where the aquifer is recharged. Springs and areas of diffuse upward leakage naturally discharge water from the aquifer and are most prevalent along the St. Johns River. Areas of discharge are reflected by depressions in the potentiometric surface. Ground-water withdrawals locally have lowered the potentiometric surface. Ground water in the Upper Floridan aquifer generally flows from potentiometric highs to potentiometric lows in a direction perpendicular to the contours.

  10. Electrolyte system strategies for anionic isotachophoresis with electrosprayionization mass-spectrometric detection. 3. The ITP spacer technique in moving-boundary systems and configurations with two self-maintained ITP subsystems

    Czech Academy of Sciences Publication Activity Database

    Gebauer, Petr; Malá, Zdeňka; Boček, Petr

    2014-01-01

    Roč. 35, č. 5 (2014), s. 746-754 ISSN 0173-0835 R&D Project s: GA ČR(CZ) GA13-05762S Keywords : electrolyte systems * ESI-MS detection * moving-boundary electrophoresis * spacers * ITP Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.028, year: 2014

  11. Potentiometric titrations of molybdenum and vanadium in aqueous and mixed so lvents

    International Nuclear Information System (INIS)

    Das, S.K.; Dhaneshwar, R.G.

    1990-01-01

    Potentiometric titration method was developed for molybdenum, employing different electrode systems. Molybdenum(VI) is reduced to molybdenum(V) by ferrous solution in presence of phosphoric acid and then titrated with potassium dichromate. It was found that ferrous concentration should be five times more than molybdenum and phosphoric acid should be 1.0 ml for 0.1N titration and 0.5 ml for lower concentration titrations. The method is also applicable to vanadium titrations. Employing Au/SCE and Pt/SCE systems, it was observed that generally curve heights obtained for platinum electrode are higher than those for gold electrode. Also for both the electrode systems, the curve heights for vanadium titrations were found to be more than those for molybdenum. Lower limits of titrations for Au/SCE system are 0.01N for molybdenum and 0.0001N for vanadium, whereas for Pt/SCE system, the lower limits obtained were 0.01N for both molybdenum and vanadium titrations. In order to improve the sensitivities of the method, the bimetallic electrode systems Au/Pt and Pt/Au were employed. Au/Pt system was found to give better results than Pt/Au systems. Addition of organic solvent was found to have beneficial effects for titrations of 0.001N and below. Methanol was found to be a better solvent than ethanol. Molybdenum titrations, at 0.0001N level could be performed in methanol with Au/Pt system, which is to b e generally preferred than Pt/Au system. (author). 7 refs., 3 tabs

  12. Potentiometric polymeric membrane electrodes for mercury detection using calixarene ionophores.

    Science.gov (United States)

    Tyagi, Sonika; Agarwal, Himanshu; Ikram, Saiqa

    2010-01-01

    It is here established that potentiometric polymeric membrane electrodes based on electrically neutral ionophores are a useful analytical tool for the detection of heavy metal ions from environmental and industrial waste water. PVC based membrane containing p-tert-butyl-calix[4]arenethioether derivative as active material along with sodiumtetraphenylborate (NaTPB) as solvent mediator and dibutylphthalate as a plasticizer in the ratio 45:9:460:310 (w/w%) (I:NaTPB:DBP:PVC) exhibits good properties with a Nernstian response of 29.50+/-1.0 mV per decade of activity and a working concentration range of 7.2 x 10(-8)-1.0 x 10(-1) M. The electrode gave more stable potential readings when used around pH 2.5-6.8 and exhibits fast response time of 14 s. The sensors were found to work satisfactorily in partially non-aqueous media up to 40% (v/v) content of acetone, methanol or ethanol and could be used over a period of 7-9 months. Excellent selectivity for Hg(2+) ions is indicated by match potential method and fixed interference method. The sensors could be used successfully in the estimation of mercury in different sample.

  13. Preparation of molecularly imprinted polymers simazine as material potentiometric sensor

    Directory of Open Access Journals (Sweden)

    Bow Yohandri

    2017-01-01

    Full Text Available Molecular imprinting technology is a promising technique for creating recognition elements for selected compounds and has been successfully applied for synthesis of environmental pollutants such as simazine. Simazine is a pesticide ingredient that is commonly used in agriculture, which has devastating effects on the environment if used excessively. Molecularly imprinted polymer (MIP provides cavities to form a particular space generated by removing the template when the polymer has formed. In this study, MIP using simazine as template had been made by the cooling-heating method and used as a material potentiometric sensor for detecting simazine. A template (simazine was incorporated into a pre-polymerization solution that contains a methacrylic acid as functional monomer, an ethylene glycol dimethacrylate as cross linker, and benzoyl peroxide as initiator. Characterization was performed by scanning electron microscope (SEM and fourier transforms infra-red (FTIR. The FTIR spectra of the MIP showed that the peaks of amine group decrease significantly, indicating that the simazine concentration decreases drastically. Characterization by SEM images showing the broadest pore size distribution with the highest number of pores in the MIP prepared under the heating time of 150 min. The MIPs therefore could be applied as a simazine sensor.

  14. CO2 Selective Potentiometric Sensor in Thick-film Technology

    Directory of Open Access Journals (Sweden)

    Ralf Moos

    2008-08-01

    Full Text Available A potentiometric sensor device based on screen-printed Nasicon films was investigated. In order to transfer the promising sensor concept of an open sodium titanate reference to thick film technology, “sodium-rich” and “sodium-poor” formulations were compared. While the “sodium-rich” composition was found to react with the ion conducting Nasicon during thermal treatment, the “sodium-poor” reference mixture was identified as an appropriate reference composition. Screen-printed sensor devices were prepared and tested with respect to CO2 response, reproducibility, and cross-interference of oxygen. Excellent agreement with the theory was observed. With the integration of a screen-printed heater, sensor elements were operated actively heated in a cold gas stream.

  15. A High-Sensitivity Potentiometric 65-nm CMOS ISFET Sensor for Rapid E. coli Screening.

    Science.gov (United States)

    Jiang, Yu; Liu, Xu; Dang, Tran Chien; Huang, Xiwei; Feng, Hao; Zhang, Qing; Yu, Hao

    2018-04-01

    Foodborne bacteria, inducing outbreaks of infection or poisoning, have posed great threats to food safety. Potentiometric sensors can identify bacteria levels in food by measuring medium's pH changes. However, most of these sensors face the limitation of low sensitivity and high cost. In this paper, we developed a high-sensitivity ion-sensitive field-effect transistor sensor. It is small sized, cost-efficient, and can be massively fabricated in a standard 65-nm complementary metal-oxide-semiconductor process. A subthreshold pH-to-time-to-voltage conversion scheme was proposed to improve the sensitivity. Furthermore, design parameters, such as chemical sensing area, transistor size, and discharging time, were optimized to enhance the performance. The intrinsic sensitivity of passivation membrane was calculated as 33.2 mV/pH. It was amplified to 123.8 mV/pH with a 0.01-pH resolution, which greatly exceeded 6.3 mV/pH observed in a traditional source-follower based readout structure. The sensing system was applied to Escherichia coli (E. coli) detection with densities ranging from 14 to 140 cfu/mL. Compared to the conventional direct plate counting method (24 h), more efficient sixfold smaller screening time (4 h) was achieved to differentiate samples' E. coli levels. The demonstrated portable, time-saving, and low-cost prescreen system has great potential for food safety detection.

  16. Commercial Applications of X Ray Spectrometric Techniques

    International Nuclear Information System (INIS)

    Wegrzynek, D.

    2013-01-01

    In the 21st century, the X-ray fluorescence (XRF) technique is widely used in process control, industrial applications and for routine elemental analysis. The technique has a multielement capability capable of detecting elements with Z ≥ 10, with a few instruments capable of detecting also elements with Z ≥ 5. It is characterized by a non-destructive analysis process and relatively good detection limits, typically one part per million, for a wide range of elements. The first commercial XRF instruments were introduced to the market about 50 years ago. They were the wavelength dispersive X ray fluorescence (WDXRF) spectrometers utilizing Bragg’s law and reflection on crystal lattices for sequential elemental analysis of sample composition. The advances made in radiation detector technology, especially the introduction of semiconductor detectors, improvements in signal processing electronics, availability and exponential growth of personal computer market led to invention of energy dispersive X ray fluorescence (EDXRF) technique. The EDXRF is more cost effective as compared to WDXRF. It also allows for designing compact instruments. Such instruments can be easily tailored to the needs of different customers, integrated with industrial installations, and also miniaturized for the purpose of in-situ applications. The versatility of the technique has been confirmed in a spectacular way by using the XRF and X-ray spectrometric techniques, among few others, during the NASA and ESA missions in search for the evidence of life and presence of water on the surface of Mars. The XRF technique has achieved its strong position within the atomic spectroscopy group of analytical techniques not only due to its versatility but also due to relatively low running costs, as compared to the commonly used methods, e.g., atomic absorption spectrometry (AAS) or inductively coupled plasma atomic emission/mass spectrometry (ICP-AES/MS). Presently, the XRF technique together with X ray

  17. Commercial Applications of X Ray Spectrometric Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Wegrzynek, D., E-mail: D.Wedgrznek@iaea.org [International Atomic Energy Agency, The IAEA Laboratories, Seibersdorf, Vienna (Austria)

    2013-07-15

    In the 21st century, the X-ray fluorescence (XRF) technique is widely used in process control, industrial applications and for routine elemental analysis. The technique has a multielement capability capable of detecting elements with Z {>=} 10, with a few instruments capable of detecting also elements with Z {>=} 5. It is characterized by a non-destructive analysis process and relatively good detection limits, typically one part per million, for a wide range of elements. The first commercial XRF instruments were introduced to the market about 50 years ago. They were the wavelength dispersive X ray fluorescence (WDXRF) spectrometers utilizing Bragg's law and reflection on crystal lattices for sequential elemental analysis of sample composition. The advances made in radiation detector technology, especially the introduction of semiconductor detectors, improvements in signal processing electronics, availability and exponential growth of personal computer market led to invention of energy dispersive X ray fluorescence (EDXRF) technique. The EDXRF is more cost effective as compared to WDXRF. It also allows for designing compact instruments. Such instruments can be easily tailored to the needs of different customers, integrated with industrial installations, and also miniaturized for the purpose of in-situ applications. The versatility of the technique has been confirmed in a spectacular way by using the XRF and X-ray spectrometric techniques, among few others, during the NASA and ESA missions in search for the evidence of life and presence of water on the surface of Mars. The XRF technique has achieved its strong position within the atomic spectroscopy group of analytical techniques not only due to its versatility but also due to relatively low running costs, as compared to the commonly used methods, e.g., atomic absorption spectrometry (AAS) or inductively coupled plasma atomic emission/mass spectrometry (ICP-AES/MS). Presently, the XRF technique together with X ray

  18. Experimental characterization of the Clear-PEM scanner spectrometric performance

    Energy Technology Data Exchange (ETDEWEB)

    Bugalho, R; Carrico, B; Ferreira, C S; Frade, M; Ferreira, M; Moura, R; Ortigao, C; Pinheiro, J F; Rodrigues, P; Rolo, I; Silva, J C; Trindade, A; Varela, J [Laboratorio de Instrumentacao e Fisica Experimental de Particulas (LIP), Av. Elias Garcia 14-1, 1000-149 Lisboa (Portugal)], E-mail: frade@lip.pt

    2009-10-15

    In the framework of the Clear-PEM project for the construction of a high-resolution and high-specificity scanner for breast cancer imaging, a Positron Emission Mammography tomograph has been developed and installed at the Instituto Portugues de Oncologia do Porto hospital. The Clear-PEM scanner is mainly composed by two planar detector heads attached to a robotic arm, trigger/data acquisition electronics system and computing servers. The detector heads hold crystal matrices built from 2 x 2 x 20 mm{sup 3} LYSO:Ce crystals readout by Hamamatsu S8550 APD arrays. The APDs are optically coupled to both ends of the 6144 crystals in order to extract the DOI information for each detected event. Each one of 12288 APD's pixels is read and controlled by Application Specific Integrated Circuits water-cooled by an external cooling unit. The Clear-PEM frontend boards innovative design results in a unprecedented integration of the crystal matrices, APDs and ASICs, making Clear-PEM the PET scanner with the highest number of APD pixels ever integrated so far. In this paper, the scanner's main technical characteristics, calibration strategies and the first spectrometric performance evaluation in a clinical environment are presented. The first commissioning results show 99.7% active channels, which, after calibration, have inter-pixel and absolute gain distributions with dispersions of, respectively, 12.2% and 15.3%, demonstrating that despite the large number of channels, the system is uniform. The mean energy resolution at 511 keV is of 15.9%, with a 8.8% dispersion, and the mean C{sub DOI}{sup -1} is 5.9%/mm, with a 7.8% dispersion. The coincidence time resolution, at 511 keV, for a energy window between 400 and 600 keV, is 5.2 ns FWHM.

  19. Potentiometric Surface of the Upper Floridan Aquifer in the St. Johns River Water Management District and Vicinity, Florida, September 2006

    Science.gov (United States)

    Kinnaman, Sandra L.; Dixon, Joann F.

    2007-01-01

    Introduction This map depicts the potentiometric surface of the Upper Floridan aquifer in the St. Johns River Water Management District and vicinity for September 2006. Potentiometric contours are based on water-level measurements collected at 571 wells during the period September 11-29, near the end of the wet season. Some contours are inferred from previouspotentiometric-surface maps with larger well networks. The potentiometric surface of the carbonate Upper Floridan aquifer responds mainly to rainfall, and more locally, to ground-water withdrawals and spring flow. Potentiometric-surface highs generally correspond to topographic highs where the aquifer is recharged. Springs and areas of diffuse upward leakage naturally discharge water from the aquifer and are most prevalent along the St. Johns River. Areas of discharge are reflected by depressions in the potentiometric surface. Ground-water withdrawals locally have lowered the potentiometric surface. Ground water in the Upper Floridan aquifer generally flows from potentiometric highs to potentiometric lows in a direction perpendicular to the contours.

  20. Determining a Solubility Product Constant by Potentiometric Titration to Increase Students' Conceptual Understanding of Potentiometry and Titrations

    Science.gov (United States)

    Grabowski, Lauren E.; Goode, Scott R.

    2017-01-01

    Potentiometric titrations are widely taught in first-year undergraduate courses to connect electrochemistry, stoichiometry, and equilibria and to reinforce acid-base titrations. Students perform a potentiometric titration that is then analyzed to determine analyte concentrations and the solubility product constant of the solid species.

  1. Mass spectrometric investigation of vinyl-substituted organic boron compounds

    International Nuclear Information System (INIS)

    Tarielashvili, V.O.; Ordzhonikidze, K.G.; Parulava, L.P.; Vakhaniya, G.V.

    1992-01-01

    Mass spectrometric investigation of vinyl-substituted organic compounds was conducted. Ionization was performed by electron shock. Possibility of determining boron isotope content is all analyzed organic boron vinyl-substituted compounds by direct method is shown. This simplifies sufficiently and lowers the price of analysis, improves its accuracy and rapidity

  2. Spectrometric determination of ammonium-nitrogen with quinol in ...

    African Journals Online (AJOL)

    Quinol is proposed as a reagent for the spectrometric determination of ammonium-nitrogen (NH4+-N) in aqueous medium. Quinol forms a pink complex with ammonium salt in aqueous medium. Hydrogen peroxide is needed for colour accentuation. The quinol/ammonium charge transfer complex has absorption maximum ...

  3. Preparation and spectrometric identification of amide derivatives with antimalaric

    International Nuclear Information System (INIS)

    Ferreira, E.J.

    1987-01-01

    The structures of polymeric compounds using spectrometric analysis of infrared, ultraviolet and protonic magnetic resonance and 13 C nuclear magnetic resonance are studied. Some structural models are used such as antimalaric-sulfones and pyrimidinic derivatives, and non-polymeric derivatives of active compounds. A comparative analysis on structures less complexes is shown. (M.J.C.). Spectrums 186 p [pt

  4. Light-Addressable Potentiometric Sensors for Quantitative Spatial Imaging of Chemical Species.

    Science.gov (United States)

    Yoshinobu, Tatsuo; Miyamoto, Ko-Ichiro; Werner, Carl Frederik; Poghossian, Arshak; Wagner, Torsten; Schöning, Michael J

    2017-06-12

    A light-addressable potentiometric sensor (LAPS) is a semiconductor-based chemical sensor, in which a measurement site on the sensing surface is defined by illumination. This light addressability can be applied to visualize the spatial distribution of pH or the concentration of a specific chemical species, with potential applications in the fields of chemistry, materials science, biology, and medicine. In this review, the features of this chemical imaging sensor technology are compared with those of other technologies. Instrumentation, principles of operation, and various measurement modes of chemical imaging sensor systems are described. The review discusses and summarizes state-of-the-art technologies, especially with regard to the spatial resolution and measurement speed; for example, a high spatial resolution in a submicron range and a readout speed in the range of several tens of thousands of pixels per second have been achieved with the LAPS. The possibility of combining this technology with microfluidic devices and other potential future developments are discussed.

  5. Automated electronic tongue based on potentiometric sensors for the determination of a trinary anionic surfactant mixture.

    Science.gov (United States)

    Cortina, Montserrat; Ecker, Christina; Calvo, Daniel; del Valle, Manuel

    2008-01-22

    An automated electronic tongue consisting of an array of potentiometric sensors and an artificial neural network (ANN) has been developed to resolve mixtures of anionic surfactants. The sensor array was formed by five different flow-through sensors for anionic surfactants, based on poly(vinyl chloride) membranes having cross-sensitivity features. Feedforward multilayer neural networks were used to predict surfactant concentrations. As a great amount of information is required for the correct modelling of the sensors response, a sequential injection analysis (SIA) system was used to automatically provide it. Dodecylsulfate (DS(-)), dodecylbenzenesulfonate (DBS(-)) and alpha-alkene sulfonate (ALF(-)) formed the three-analyte study case resolved in this work. Their concentrations varied from 0.2 to 4mM for ALF(-) and DBS(-) and from 0.2 to 5mM for DS(-). Good prediction ability was obtained with correlation coefficients better than 0.933 when the obtained values were compared with those expected for a set of 16 external test samples not used for training.

  6. Potentiometric determination of ibuprofen, indomethacin and naproxen using an artificial neural network calibration

    Directory of Open Access Journals (Sweden)

    A. HAKAN AKTAŞ

    2008-01-01

    Full Text Available In this study, three anti-inflammatory agents, namely ibuprofen, indomethacin and naproxen, were titrated potentiometrically using tetrabutylammonium hydroxide in acetonitrile solvent under a nitrogen atmosphere at 25 °C. MATLAB 7.0 software was applied for data treatment as a multivariate calibration tool in the potentiometric titration procedure. An artificial neural network (ANN was used as a multivariate calibration tool in the potentiometric titration to model the complex non-linear relationship between ibuprofen, indomethacin and naproxen concentrations and the millivolt (mV of the solutions measured after the addition of different volumes of the titrant. The optimized network predicted the concentrations of agents in synthetic mixtures. The results showed that the employed ANN can precede the titration data with an average relative error of prediction of less than 2.30 %.

  7. Determination of actinides by alpha spectrometric methods

    International Nuclear Information System (INIS)

    Galanda, D.

    2011-01-01

    defined attributes of mass activities of radionuclides in oyster mushroom's sporocarps compared to their sub-base. We used two methods to separate the monitored radionuclides in a radiochemical analyse. The first of them was an extraction fluid - fluid with Aliquat-336 to separate Pu and TOPO to separate Am. The second method was a proceeding modified by us and utilizing principles of an extraction chromatography with TRU Resin and DGA Resin sorbents made by Eichrom Company. An effectivity and a suitability of both applied methods were monitored following the attributes of radiochemical extractions used in tracer's radionuclides 242 Pu a 243 Am in this particular type of environmental samples. The reliability of the modified methodology, in accordance to selected criteria for validation of analytical method, was proved by comparison of both above mentioned methods. material delivered from IAEA, which presented a soil sample with code identification Soil IAEA-375. The obtained values of mass activities of 239 + 240 Pu, 239 Pu and 241 Am used in reference material, demonstrated a conformity with IAEA values, whereby we fulfilled one of the significant conditions of validate process. At the end of this thesis we applied the modified method of extraction chromatography with UTEVA Resin sorbent to define mass activities of uranium on soil and water samples where we monitored attributes of radiochemical extractions of 232 U tracer's radionuclide as the criteria of utilizability. The reliability of our modified method was verified by participation in international interlaboratory comparative proficiency tests and our results were in accordance with results of the reference laboratory. It means also a fulfilment of notable standard of the validate process. The results of all realized experimentations of radionuclides separation whether by extraction fluid - fluid or by extraction chromatography were determined by alpha-spectrometric measurements. (author)

  8. Biocompatible Poly(catecholamine)-Film Electrode for Potentiometric Cell Sensing.

    Science.gov (United States)

    Kajisa, Taira; Yanagimoto, Yoshiyuki; Saito, Akiko; Sakata, Toshiya

    2018-02-23

    Surface-coated poly(catecholamine) (pCA) films have attracted attention as biomaterial interfaces owing to their biocompatible and physicochemical characteristics. In this paper, we report that pCA-film-coated electrodes are useful for potentiometric biosensing devices. Four different types of pCA film, l-dopa, dopamine, norepinephrine, and epinephrine, with thicknesses in the range of 7-27 nm were electropolymerized by oxidation on Au electrodes by using cyclic voltammetry. By using the pCA-film electrodes, the pH responsivities were found to be 39.3-47.7 mV/pH within the pH range of 1.68 to 10.01 on the basis of the equilibrium reaction with hydrogen ions and the functional groups of the pCAs. The pCA films suppressed nonspecific signals generated by other ions (Na + , K + , Ca 2+ ) and proteins such as albumin. Thus, the pCA-film electrodes can be used in pH-sensitive and pH-selective biosensors. HeLa cells were cultivated on the surface of the pCA-film electrodes to monitor cellular activities. The surface potential of the pCA-film electrodes changed markedly because of cellular activity; therefore, the change in the hydrogen ion concentration around the cell/pCA-film interface could be monitored in real time. This was caused by carbon dioxide or lactic acid that is generated by cellular respiration and dissolves in the culture medium, resulting in the change of hydrogen concentration. pCA-film electrodes are suitable for use in biocompatible and pH-responsive biosensors, enabling the more selective detection of biological phenomena.

  9. A Porphyrin Based Potentiometric Sensor for Zn2+ Determination

    Directory of Open Access Journals (Sweden)

    H. Lang

    2003-07-01

    Full Text Available PVC based membranes of disodium salt of porphyrin 3,7,12,17-tetramethyl-8, 13-divinyl 2,18-porphine dipropionic acid (I as ionophore with sodium tetra phenyl borate (NaTPB as anion excluder and dibutyl phthalate (DBP, dioctyl phthalate (DOP, dibutyl butyl phosphonate (DBBP, tris(2- ethyl hexylphosphate (TEP, tri-n-butylphosphate (TBP and 1- chloronaphthalene (CN as plasticizing solvent mediators were prepared and constructed for determination of Zn(II. The PVC based membrane of (I with DBBP as plasticizer and having anion excluder, NaTPB in the ratio PVC: I: NaTPB: DBBP (150: 10: 2: 200 gave the best results in terms of working concentration range (1.3×10-5-1.0 ×10-1M with a Nernstian slope (30.0 mV/decade of activity. The useful pH range of the sensor is 3.0 –7.4, beyond which a drift in potential was observed. The response time of the sensor is 10s and the lifetime was about 2 months during which it could be used without any measurable divergence. It had good stability and reproducibility. The membrane worked satisfactorily in non-aqueous medium up to 40% (v/v non-aqueous content. The selectivity coefficient values indicate that the electrode is highly selective for Zn2+ over a number of other cations except Na+ and Cd2+. Although Na+ and Cd2+ are likely to cause some interference, they would not interfere if present at the concentrations < 1 ×10-5 and < 5 ×10-5 M, respectively. The electrode has been used as an indicator electrode to determine the end point in the potentiometric titration of Zn2+ with EDTA.

  10. Use of 3-(4-hydroxyphenyl)propionic acid as electron donating compound in a potentiometric aflatoxin M1-immunosensor

    International Nuclear Information System (INIS)

    Rameil, Steffen; Schubert, Peter; Grundmann, Peter; Dietrich, Richard; Maertlbauer, Erwin

    2010-01-01

    We developed a potentiometric aflatoxin M 1 -immunosensor which utilizes 3-(4-hydroxyphenyl)propionic acid (p-HPPA) as electron donating compound for horseradish peroxidase (HRP; EC 1.11.1.7). The assay system consists of a polypyrrole-surface-working electrode coated with a polyclonal anti-M 1 antibody (pAb-AFM 1 ), a Ag/AgCl reference electrode and a HRP-aflatoxin B 1 conjugate (HRP-AFB 1 conjugate). To optimize the potentiometric measuring system p-HPPA as well as related compounds serving as electron donating compounds were compared. Also the influence of different buffer systems, varying pH and substrate concentrations on signal intensity was investigated. Our results suggest that reaction conditions that favor the formation of Pummerer's type ketones lead to an increase in signal intensity rather than formation of fluorescent dye. Comparison with commercial ready-to-use HRP electron donating compounds such as 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), o-phenylenediamine (OPD) or 3,3',5,5'-tetramethylbenzidine (TMB) showed that only 34%, 77% and 49% of the signal intensity of p-HPPA were reached, respectively. The optimized assay had a detection limit of 40 pg mL -1 and allowed detection of 500 pg mL -1 (FDA action limit) aflatoxin M 1 (AFM 1 ) in pasteurized milk and UHT-milk containing 0.3-3.8% fat within 10 min without any sample treatment. The working range was between 250 and 2000 pg mL -1 AFM 1 .

  11. Comparison of methods for accurate end-point detection of potentiometric titrations

    International Nuclear Information System (INIS)

    Villela, R L A; Borges, P P; Vyskočil, L

    2015-01-01

    Detection of the end point in potentiometric titrations has wide application on experiments that demand very low measurement uncertainties mainly for certifying reference materials. Simulations of experimental coulometric titration data and consequential error analysis of the end-point values were conducted using a programming code. These simulations revealed that the Levenberg-Marquardt method is in general more accurate than the traditional second derivative technique used currently as end-point detection for potentiometric titrations. Performance of the methods will be compared and presented in this paper

  12. Geostatistical analysis of potentiometric data in Wolfcamp aquifer of the Palo Duro Basin, Texas

    International Nuclear Information System (INIS)

    Harper, W.V.; Furr, J.M.

    1986-04-01

    This report details a geostatistical analysis of potentiometric data from the Wolfcamp aquifer in the Palo Duro Basin, Texas. Such an analysis is a part of an overall uncertainty analysis for a high-level waste repository in salt. Both an expected potentiometric surface and the associated standard error surface are produced. The Wolfcamp data are found to be well explained by a linear trend with a superimposed spherical semivariogram. A cross-validation of the analysis confirms this. In addition, the cross-validation provides a point-by-point check to test for possible anomalous data

  13. Comparison of methods for accurate end-point detection of potentiometric titrations

    Science.gov (United States)

    Villela, R. L. A.; Borges, P. P.; Vyskočil, L.

    2015-01-01

    Detection of the end point in potentiometric titrations has wide application on experiments that demand very low measurement uncertainties mainly for certifying reference materials. Simulations of experimental coulometric titration data and consequential error analysis of the end-point values were conducted using a programming code. These simulations revealed that the Levenberg-Marquardt method is in general more accurate than the traditional second derivative technique used currently as end-point detection for potentiometric titrations. Performance of the methods will be compared and presented in this paper.

  14. Determination of the titratable acidity and the pH of wine based on potentiometric flow injection analysis.

    Science.gov (United States)

    Vahl, Katja; Kahlert, Heike; von Mühlen, Lisandro; Albrecht, Anja; Meyer, Gabriele; Behnert, Jürgen

    2013-07-15

    A FIA system using a pH-sensitive detector based on a graphite/quinhydrone/silicone composite electrode was applied to determine sequentially the titratable acidity and the pH of wine, as well as the sum of calcium and magnesium ions. For all measurements the same FIA configuration was used employing different carrier solutions. The results for the determination of acidity and pH are in good agreement with those obtained by classical potentiometric titrations and by pH measurements using a conventional glass electrode. The standard deviation was less than 1.5% for both kinds of measurements and the sample volume was 150 μL. The method allows about 40 determinations of titratable acidity per hour and 30 pH measurements per hour. The titration method can be adjusted to the legal requirements in USA and Europe. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Determination of pKa values of benzoxa-, benzothia- and benzoselena-zolinone derivatives by capillary electrophoresis. Comparison with potentiometric titration and spectrometric data.

    Science.gov (United States)

    Foulon, C; Duhal, N; Lacroix-Callens, B; Vaccher, C; Bonte, J P; Goossens, J F

    2007-07-01

    Acidity constants of benzoxa-, benzothia- and benzoselena-zolinone derivatives were determined by capillary electrophoresis, potentiometry and spectrophotometry experiments. These three analytical techniques gave pK(a) results that were in good agreement. A convenient, accurate and precise method for the determination of pK(a) was developed to measure changes in acidity constants induced by heteroatom or 6-benzoyl substituted derivatives. pK(a) values were determined simultaneously for two compounds characterized by different electrophoretic mobility (micro(e)) and pK(a) value and in the presence of an analogous neutral marker.

  16. Implementation of the automated potentiometric titration method for total U at the CNEN Safeguard Laboratory, Brazil; Implementacao do metodo de titulacao potenciometrica automatizado para U total no Laboratorio de Salvaguardas da CNEN, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Cristiano, Barbara F.G.; Delgado, Jose U.; Araujo, Radier M.S. de; Silva, Jose W.S. da; Barros, Pedro D. de, E-mail: barbara@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2009-07-01

    Brazilian nuclear facilities, in accordance with the regulation CNEN-NN-2.02, must have available measurement systems which allow to determine their nuclear material inventories. For the evaluation and the follow up the performance of the involved laboratories in those measurement systems, the accomplishment of interlaboratory comparison programmes becomes fundamental. Therefore, the implementation of the potentiometric titration viewing the characterization of uranium samples, represents an reference element for the Brazilian programs

  17. Potentiometric measurement of polymer-membrane electrodes based on lanthanum

    Energy Technology Data Exchange (ETDEWEB)

    Saefurohman, Asep, E-mail: saefurohman.asep78@Gmail.com; Buchari,, E-mail: saefurohman.asep78@Gmail.com; Noviandri, Indra, E-mail: saefurohman.asep78@Gmail.com [Department of Chemistry, Bandung Institute of Technology (Indonesia); Syoni [Department of Metallurgy Engineering, Bandung Institute of Technology (Indonesia)

    2014-03-24

    Quantitative analysis of rare earth elements which are considered as the standard method that has a high accuracy, and detection limits achieved by the order of ppm is inductively coupled plasma atomic emission spectroscopy (ICPAES). But these tools are expensive and valuable analysis of the high cost of implementation. In this study be made and characterized selective electrode for the determination of rare earth ions is potentiometric. Membrane manufacturing techniques studied is based on immersion (liquid impregnated membrane) in PTFE 0.5 pore size. As ionophores to be used tri butyl phosphate (TBP) and bis(2-etylhexyl) hydrogen phosphate. There is no report previously that TBP used as ionophore in polymeric membrane based lanthanum. Some parameters that affect the performance of membrane electrode such as membrane composition, membrane thickness, and types of membrane materials studied in this research. Manufacturing of Ion Selective Electrodes (ISE) Lanthanum (La) by means of impregnation La membrane in TBP in kerosene solution has been done and showed performance for ISE-La. FTIR spectrum results for PTFE 0.5 pore size which impregnated in TBP and PTFE blank showed difference of spectra in the top 1257 cm{sup −1}, 1031 cm{sup −1} and 794.7 cm{sup −1} for P=O stretching and stretching POC from group −OP =O. The result showed shift wave number for P =O stretching of the cluster (−OP=O) in PTFE-TBP mixture that is at the peak of 1230 cm{sup −1} indicated that no interaction bond between hydroxyl group of molecules with molecular clusters fosforil of TBP or R{sub 3}P = O. The membrane had stable responses in pH range between 1 and 9. Good responses were obtained using 10{sup −3} M La(III) internal solution, which produced relatively high potential. ISE-La showed relatively good performances. The electrode had a response time of 29±4.5 second and could be use for 50 days. The linear range was between 10{sup −5} and 10{sup −1} M.

  18. Persistence length of carboxymethyl cellulose as evaluated from size exclusion chromatography and potentiometric titrations.

    NARCIS (Netherlands)

    Hoogendam, C.W.; Keizer, de A.; Cohen Stuart, M.A.; Bijsterbosch, B.H.; Smit, J.A.M.; Dijk, van J.A.P.P.; Horst, van der P.M.; Batelaan, J.G.

    1998-01-01

    The intrinsic persistence length of carboxymethyl cellulose (CMC) is determined by size exclusion chromatography in combination with multiangle laser light scattering (SEC-MALLS) as well as from potentiometric titrations. Samples with degree of substitution (ds) ranging from 0.75 to 1.25 were

  19. Lead in Hair and in Red Wine by Potentiometric Stripping Analysis: The University Students' Design.

    Science.gov (United States)

    Josephsen, Jens

    1985-01-01

    A new program for training upper secondary school chemistry teachers (SE 537 693) depends heavily on student project work. A project in which lead in hair and in red wine was examined by potentiometric stripping analysis is described and evaluated. (JN)

  20. BIOSENSOR FOR DIRECT DETERMINATION OF ORGANOPHOSPHATE NERVE AGENTS. 1. POTENTIOMETRIC ENZYME ELECTRODE. (R823663)

    Science.gov (United States)

    A potentiometric enzyme electrode for the direct measurement of organophosphate (OP)nerve agents was developed. The basic element of this enzyme electrode was a pH electrodemodified with an immobilized organophosphorus hydrolase (OPH) layer formed by cross-linkingOPH ...

  1. Relationship between potentiometric measurements, sensorial analysis, and some substances responsible for aroma degradation of white wines.

    Science.gov (United States)

    Silva Ferreira, A C; Oliveira, Carla; Hogg, T; Guedes de Pinho, P

    2003-07-30

    Oxidative degradation of white wines can be described sensorially as developing from a loss at positive aroma characteristics, through the development of negative aromas to a linel stage of chromatic alterations. This work attempts to relate the oxidation "status" evaluate by potentiometric titrations, with sensorial degradation and the levels of substances responsible for "off-flavors", such as methional and phenylacetaldehyde. The potentiometric titration employed measures the most powerful antioxidants of white wines (e.g., those which more rapidly consume oxygen). Considering that aromatic precedes chromatic degradation, resistance to oxidation (ROX) constitutes a useful indicator of resistance to oxidation. Sensorial degradation (ID), potentiometric measures, and volatiles were determined both in samples submitted to a "forced aging" protocol and normal aged white wines. High correlation values were observed between ROX and the ID, in both sets (r > 0.87). ID is better explained by ROX values than by the indicated wine age or by the "degree of browning" (Abs = 420 nm). It was also observed that in samples with ROX values higher than 10, the concentration of methional and phenylacetaldehyde were above their respective odor threshold. Finally, it was observed that there is a relationship between oxygen consumption and the respective ROX. Although these results seem very promising, they needed to be further complemented in order to estimate the shelf life of a white wine using potentiometric titrations.

  2. Solid-state potentiometric biosensors for pH quantification in biological samples

    NARCIS (Netherlands)

    Ivan, M.G.; Wiegersma, S.; Sweelssen, J.; Saalmink, M.; Boersma, A.

    2011-01-01

    This paper reports on manufacturing and characterization of an all-solid-state potentiometric sensor aimed at monitoring pH in dialysate or blood plasma for patients who undergo dialysis. The sensing polymer-based membrane, coated on top of the Au working electrodes, contains a polymer matrix -

  3. Computer analysis of potentiometric data of complexes formation in the solution

    Science.gov (United States)

    Jastrzab, Renata; Kaczmarek, Małgorzata T.; Tylkowski, Bartosz; Odani, Akira

    2018-02-01

    The determination of equilibrium constants is an important process for many branches of chemistry. In this review we provide the readers with a discussion on computer methods which have been applied for elaboration of potentiometric experimental data generated during complexes formation in solution. The review describes both: general basis of modeling tools and examples of the use of calculated stability constants.

  4. Non-euclidean simplex optimization. [Application to potentiometric titration of Pu

    Energy Technology Data Exchange (ETDEWEB)

    Silver, G.L.

    1977-08-15

    Geometric optimization techniques useful for studying chemical equilibrium traditionally rely upon principles of euclidean geometry, but such algorithms may also be based upon principles of a non-euclidean geometry. The sequential simplex method is adapted to the hyperbolic plane, and application of optimization to problems such as the potentiometric titration of plutonium is suggested.

  5. Determination of titanium and vanadium in aqueous solutions by potentiometric titration

    International Nuclear Information System (INIS)

    Sibirkin, A.A.; Elliev, Yu.E.

    1996-01-01

    Possibility of titanium and vanadium determination at their combined presence by bichromatometric chromometric titration with potentiometric indication of end point is shown. The technique is developed which allows to determine titanium and vanadium with relative standard derivation ±2% in amounts not less than 50 and 100 mg respectively

  6. Automation of potentiometric titration for the determination of uranium in nuclear fuel materials

    International Nuclear Information System (INIS)

    Kelkar, Anoop; Pandey, Ashish; Kapoor, Y.S.; Kumar, Manish; Singh, Mamta; Fulzele, Ajeet; Prakash, Amrit; Afzal, Mohd; Panakkal, J.P.

    2010-01-01

    Advanced Fuel Fabrication Facility is fabricating various types of mixed oxide fuels, namely for PHWR, BWR, FBTR and PFBR. Precise determination of uranium in MOX fuel sample is important to get desired burn up in the reactor. The modified Davies and Gray method is routinely used for the potentiometric titration of uranium

  7. Ni(III) - a new oxidant for the potentiometric determination of plutonium

    International Nuclear Information System (INIS)

    Gopinath, N.; Rama Rao, G.A.; Natarajan, P.R.

    1986-01-01

    Ni(III) was employed as an oxidant for the quantitative oxidation of plutonium to its hexavalent state and this makes possible to determine plutonium concentrations potentiometrically by the Fe(II)-dichromate redox titration method. The unreacted oxidant is completely reduced by sulphamic acid prior to the determination of plutonium. (author)

  8. Label-free and substrate-free potentiometric aptasensing using polycation-sensitive membrane electrodes.

    Science.gov (United States)

    Ding, Jiawang; Chen, Yan; Wang, Xuewei; Qin, Wei

    2012-02-21

    A potentiometric label-free and substrate-free (LFSF) aptasensing strategy which eliminates the labeling, separation, and immobilization steps is described in this paper. An aptamer binds specifically to a target molecule via reaction incubation, which could induce a change in the aptamer conformation from a random coil-like configuration to a rigid folded structure. Such a target binding-induced aptamer conformational change effectively prevents the aptamer from electrostatically interacting with the protamine binding domain. This could either shift the response curve for the potentiometric titration of the aptamer with protamine as monitored by a conventional polycation-sensitive membrane electrode or change the current-dependent potential detected by a protamine-conditioned polycation-sensitive electrode with the pulsed current-driven ion fluxes of protamine across the polymeric membrane. Using adenosine triphosphate (ATP) as a model analyte, the proposed concept offers potentiometric detection of ATP down to the submicromolar concentration range and has been applied to the determination of ATP in HeLa cells. In contrast to the current LFSF aptasensors based on optical detection, the proposed strategy allows the LFSF biosensing of aptamer/target binding events in a homogeneous solution via electrochemical transduction. It is anticipated that the proposed strategy will lay a foundation for development of potentiometric sensors for LFSF aptasensing of a variety of analytes where target binding-induced conformational changes such as the formation of folded structures and the opening of DNA hairpin loops are involved.

  9. Potentiometric Titrations for Measuring the Capacitance of Colloidal Photodoped ZnO Nanocrystals.

    Science.gov (United States)

    Brozek, Carl K; Hartstein, Kimberly H; Gamelin, Daniel R

    2016-08-24

    Colloidal semiconductor nanocrystals offer a unique opportunity to bridge molecular and bulk semiconductor redox phenomena. Here, potentiometric titration is demonstrated as a method for quantifying the Fermi levels and charging potentials of free-standing colloidal n-type ZnO nanocrystals possessing between 0 and 20 conduction-band electrons per nanocrystal, corresponding to carrier densities between 0 and 1.2 × 10(20) cm(-3). Potentiometric titration of colloidal semiconductor nanocrystals has not been described previously, and little precedent exists for analogous potentiometric titration of any soluble reductants involving so many electrons. Linear changes in Fermi level vs charge-carrier density are observed for each ensemble of nanocrystals, with slopes that depend on the nanocrystal size. Analysis indicates that the ensemble nanocrystal capacitance is governed by classical surface electrical double layers, showing no evidence of quantum contributions. Systematic shifts in the Fermi level are also observed with specific changes in the identity of the charge-compensating countercation. As a simple and contactless alternative to more common thin-film-based voltammetric techniques, potentiometric titration offers a powerful new approach for quantifying the redox properties of colloidal semiconductor nanocrystals.

  10. Concentration-related response potentiometric titrations to study the interaction of small molecules with large biomolecules.

    Science.gov (United States)

    Hamidi-Asl, Ezat; Daems, Devin; De Wael, Karolien; Van Camp, Guy; Nagels, Luc J

    2014-12-16

    In the present paper, the utility of a special potentiometric titration approach for recognition and calculation of biomolecule/small-molecule interactions is reported. This approach is fast, sensitive, reproducible, and inexpensive in comparison to the other methods for the determination of the association constant values (Ka) and the interaction energies (ΔG). The potentiometric titration measurement is based on the use of a classical polymeric membrane indicator electrode in a solution of the small-molecule ligand. The biomolecule is used as a titrant. The potential is measured versus a reference electrode and transformed into a concentration-related signal over the entire concentration interval, also at low concentrations, where the millivolt (y-axis) versus log canalyte (x-axis) potentiometric calibration curve is not linear. In the procedure, Ka is calculated for the interaction of cocaine with a cocaine binding aptamer and with an anticocaine antibody. To study the selectivity and cross-reactivity, other oligonucleotides and aptamers are tested, as well as other small ligand molecules such as tetrakis(4-chlorophenyl)borate, metergoline, lidocaine, and bromhexine. The calculated Ka compared favorably to the value reported in the literature using surface plasmon resonance. The potentiometric titration approach called "concentration-related response potentiometry" is used to study molecular interaction for seven macromolecular target molecules and four small-molecule ligands.

  11. Combined Voltammetric-Potentiometric Sensor with the Silver Solid Amalgam Link for Electroanalytical Measurements

    Czech Academy of Sciences Publication Activity Database

    Josypčuk, Bohdan; Novotný, Ladislav

    2002-01-01

    Roč. 14, č. 24 (2002), s. 1739-1741 ISSN 1040-0397 R&D Projects: GA ČR GV204/97/K084 Institutional research plan: CEZ:AV0Z4040901 Keywords : combined voltammetric-potentiometric sensors * solid amalgam Subject RIV: CG - Electrochemistry Impact factor: 1.783, year: 2002

  12. Potentiometric determination of the 'formal' hydrolysis ratio of aluminium species in aqueous solutions

    International Nuclear Information System (INIS)

    Fournier, Agathe C.; Shafran, Kirill L.; Perry, Carole C.

    2008-01-01

    The 'formal' hydrolysis ratio (h = C(OH - ) added /C(Al) total ) of hydrolysed aluminium-ions is an important parameter required for the exhaustive and quantitative speciation-fractionation of aluminium in aqueous solutions. This paper describes a potentiometric method for determination of the formal hydrolysis ratio based on an automated alkaline titration procedure. The method uses the point of precipitation of aluminium hydroxide as a reference (h = 3.0) in order to calculate the initial formal hydrolysis ratio of hydrolysed aluminium-ion solutions. Several solutions of pure hydrolytic species including aluminium monomers (AlCl 3 ), Al 13 polynuclear cluster ([Al 13 O 4 (OH) 24 (H 2 O) 12 ] 7+ ), Al 30 polynuclear cluster ([Al 30 O 8 (OH) 56 (H 2 O) 26 ] 18+ ) and a suspension of nanoparticulate aluminium hydroxide have been used as 'reference standards' to validate the proposed potentiometric method. Other important variables in the potentiometric determination of the hydrolysis ratio have also been optimised including the concentration of aluminium and the type and strength of alkali (Trizma-base, NH 3 , NaHCO 3 , Na 2 CO 3 and KOH). The results of the potentiometric analysis have been cross-verified by quantitative 27 Al solution nuclear magnetic resonance ( 27 Al NMR) measurements. The 'formal' hydrolysis ratio of a commercial basic aluminium chloride has been measured as an example of a practical application of the developed technique

  13. Statistical evaluation of an interlaboratory comparison for the determination of uranium by potentiometric titration

    International Nuclear Information System (INIS)

    Ketema, D.J.; Harry, R.J.S.; Zijp, W.L.

    1990-09-01

    Upon request of the ESARDA working group 'Low enriched uranium conversion - and fuel fabrication plants' an interlaboratory comparison was organized, to assess the precision and accuracy concerning the determination of uranium by the potentiometric titration method. This report presents the results of a statistical evaluation on the data of the first phase of this exercise. (author). 9 refs.; 5 figs.; 24 tabs

  14. Electrospray Ionization Mass Spectrometric Analysis of Highly Reactive Glycosyl Halides

    Directory of Open Access Journals (Sweden)

    Lajos Kovács

    2012-07-01

    Full Text Available Highly reactive glycosyl chlorides and bromides have been analysed by a routine mass spectrometric method using electrospray ionization and lithium salt adduct-forming agents in anhydrous acetonitrile solution, providing salient lithiated molecular ions [M+Li]+, [2M+Li]+ etc. The role of other adduct-forming salts has also been evaluated. The lithium salt method is useful for accurate mass determination of these highly sensitive compounds.

  15. Neutron activation and mass spectrometric measurement of /sup 129/I

    International Nuclear Information System (INIS)

    Strebin, R.S. Jr.; Brauer, F.P.; Kaye, J.H.; Rapids, M.S.; Stoffels, J.J.

    1987-11-01

    An integrated procedure has been developed for measurement of /sup 129/I by neutron activation analysis and mass spectrometry. An iodine isolation procedure previously used for neutron activation has been modified to provide separated iodine suitable for mass spectrometric measurement as well. Agreement between both methods has been achieved within error limits. The measurement limit by each method is about 10/sup 7/ atoms (2 fg) of /sup 129/I. 13 refs,. 4 figs., 1 tab

  16. Potentiometric-level monitoring program, Mississippi and Louisiana: Annual status report for fiscal year 1985

    International Nuclear Information System (INIS)

    1986-10-01

    Potentiometric-level data presented in this report were collected at 82 wells in Mississippi and Louisiana from October 1984 through September 1985. These wells are located near Richton and Cypress Creek Domes in Mississippi and Vacherie dome in Louisiana. Three wells were reinstated to the program during this period. Two previously destroyed wells were deleted from the program. Protective barriers were installed around 26 shallow borings in Mississippi. Cursory analysis of the data in Mississippi indicated minimal, if any, change in potentiometric level during the past year in the Citronelle, Hattiesburg, Cockfield, Sparta, and Wilcox Formations. A slight decline, on the order of 0.3 meter (1 foot), occurred during the past year in well MCCG-1, which is screened in the caprock of Cypress Creek Dome. The potentiometric level in well MRIG-9, in the caprock of Richton Dome, stabilized during fiscal year 1985 following 5 years of increase. The Catahoula Formation experienced a continuing decline of about 0.3 meter/year (1 foot/year). Well MH-5C, screened in the Cook Mountain Formation, showed a continuing, long-term, upward trend on the order of 1.5 meters (4.9 feet) during the past year. The potentiometric level of well MH-8C, screened in the Cook Mountain Formation, stabilized during fiscal year 1985, following 5 years of large annual increases. Wells screened in the Austin Formation in Louisiana showed a downward trend of 0.3 to 1 meter (1 to 3.3 feet) during fiscal year 1985. Other formations in Louisiana generally showed no change in potentiometric level

  17. A new approach to flow-batch titration. A monosegmented flow titrator with coulometric reagent generation and potentiometric or biamperometric detection.

    Science.gov (United States)

    de Aquino, Emerson Vidal; Rohwedder, Jarbas José Rodrigues; Pasquini, Celio

    2006-11-01

    Monosegmented flow analysis (MSFA) has been used as a flow-batch system to produce a simple, robust, and mechanized titrator that enables true titrations to be performed without the use of standards. This paper also introduces the use of coulometry with monosegmented titration by proposing a versatile flow cell. Coulometric generation of the titrand is attractive for titrations performed in monosegmented systems, because the reagent can be added without increasing the volume of sample injected. Also, biamperomeric and potentiometric detection of titration end-points can increase the versatility of the monosegmented titrator. The cell integrates coulometric generation of the titrand with detection of end-point by potentiometry or biamperometry. The resulting titrator is a flow-batch system in which the liquid monosegment, constrained by the interfaces of the gaseous carrier stream, plays the role of a sample of known volume to be titrated. The system has been used for determination of ascorbic acid, by coulometric generation of I2 with biamperometric detection, and for determination of Fe(II), by coulometric generation of Ce(IV) with potentiometric detection of the end-point, both in feed supplements.

  18. Complexação da tetraciclina, da oxitetraciclina e da clortetraciclina com o catião cobre (II. Estudo potenciométrico Tetracycline, oxytetracycline and chlortetracycline complexation with copper (II. Potentiometric study

    Directory of Open Access Journals (Sweden)

    Cristina M. C. M. Couto

    2000-08-01

    Full Text Available Stability constants of complexes formed by copper (II with three different tetracyclines (tetracycline, oxytetracycline and chlortetracycline have been determined potentiometrically with an automatic system in aqueous medium at 25,0 ± 0,2 ºC and I = 0,1 mol L-1 NaNO3. The protonation constants of the three tetracyclines were also determined under the same conditions. The distribution of the complexes was then simulated at therapeutic levels of the drugs.

  19. Potentiometric surface of the Upper Floridan aquifer in Florida and parts of Georgia, South Carolina, and Alabama, May – June 2010

    Science.gov (United States)

    Kinnaman, Sandra L.; Dixon, Joann F.

    2011-01-01

    The Floridan aquifer system covers nearly 100,000 square miles in the southeastern United States throughout Florida and in parts of Georgia, South Carolina, and Alabama, and is one of the most productive aquifers in the world (Miller, 1990). This sequence of carbonate rocks is hydraulically connected and is over 300 feet thick in south Florida and thins toward the north. Typically, this sequence is subdivided into the Upper Floridan aquifer, the middle confining unit, and the Lower Floridan aquifer. The majority of freshwater is contained in the Upper Floridan aquifer and is used for water supply (Miller, 1986). The Lower Floridan aquifer contains fresh to brackish water in northeastern Florida and Georgia, while in south Florida it is saline. The potentiometric surface of the Upper Floridan aquifer in May–June 2010 shown on this map was constructed as part of the U.S. Geological Survey Floridan Aquifer System Groundwater Availability Study (U.S. Geological Survey database, 2011). Previous synoptic measurements and regional potentiometric maps of the Upper Floridan aquifer were prepared for May 1980 (Johnston and others, 1981) and May 1985 (Bush and others, 1986) as part of the Floridan Regional Aquifer System Analysis.

  20. Potentiometric analytical microsystem based on the integration of a gas-diffusion step for on-line ammonium determination in water recycling processes in manned space missions.

    Science.gov (United States)

    Calvo-López, Antonio; Ymbern, Oriol; Puyol, Mar; Casalta, Joan Manel; Alonso-Chamarro, Julián

    2015-05-18

    The design, construction and evaluation of a versatile cyclic olefin copolymer (COC)-based continuous flow potentiometric microanalyzer to monitor the presence of ammonium ion in recycling water processes for future manned space missions is presented. The microsystem integrates microfluidics, a gas-diffusion module and a detection system in a single substrate. The gas-diffusion module was integrated by a hydrophobic polyvinylidene fluoride (PVDF) membrane. The potentiometric detection system is based on an all-solid state ammonium selective electrode and a screen-printed Ag/AgCl reference electrode. The analytical features provided by the analytical microsystem after the optimization process were a linear range from 0.15 to 500 mg L(-1) and a detection limit of 0.07 ± 0.01 mg L(-1). Nevertheless, the operational features can be easily adapted to other applications through the modification of the hydrodynamic variables of the microfluidic platform. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Spectrometric analog-to-digital converter

    International Nuclear Information System (INIS)

    Ormandzhiev, S.I.; Jordanov, V.T.

    1988-01-01

    Converter of digit-by-digit counterbalancing with slipping dial with number of channels equal to total number of states of the main digital-to-analog converter of digit-by-digit counterbalancing systems is presented. Algorithm for selection of digital-to-analog converters, which must be used by means of computer is suggested

  2. Determination of trace metal ions via on-line separation and preconcentration by means of chelating Sepharose beads in a sequential injection lab-on-valve (SI-LOV) system coupled to electrothermal atomic absorption spectrometric detection

    DEFF Research Database (Denmark)

    Long, Xiangbao; Hansen, Elo Harald; Miró, Manuel

    2005-01-01

    The analytical performance of an on-line sequential injection lab-on-valve (SI-LOV) system using chelating Sepharose beads as sorbent material for the determination of ultra trace levels of Cd(II), Pb(II) and Ni(II) by electrothermal atomic absorption spectrometry (ETAAS) is described and discussed...

  3. Increment memory module for spectrometric data recording

    International Nuclear Information System (INIS)

    Zhuchkov, A.A.; Myagkikh, A.I.

    1988-01-01

    Incremental memory unit designed to input differential energy spectra of nuclear radiation is described. ROM application as incremental device has allowed to reduce the number of elements and do simplify information readout from the unit. 12-bit 2048 channels present memory unit organization. The device is connected directly with the bus of microprocessor systems similar to KR 580. Incrementation maximal time constitutes 3 mks. It is possible to use this unit in multichannel counting mode

  4. Mass spectrometric analysis of simple hydrogen compounds; Analyse de composes hydrogenes simples au spectrometre de masse

    Energy Technology Data Exchange (ETDEWEB)

    Nief, C; Botter, R [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    A uranium furnace is inserted in the gas inlet line of a mass spectrometer between the leak and the source. The line is fed with simple hydrogen compounds (H{sub 2}O, NH{sub 3}, H{sub 2}S) which are in this way reduced to hydrogen gas. Memory effects are largely avoided by heating the sample line to 90 deg. C. The speed of the isotopic analysis is only slightly less than that of hydrogen gas itself; the accuracy is better due to the reduction of fractionating effects in the leak. For the absolute measurements of deuterium in water, the presence of H{sub 3}{sup +} is a problem. Water samples, prepared by mixing an unknown light water sample with different amounts of heavy water, are equilibrated with hydrogen sulphide and analysis of the two phases of each sample enables the zero of the concentration scale to be determined from the point of intersection of the two curves obtained by plotting mixture composition against the observed isotope ratio in the two phases. The whole experiment can be carried out in the apparatus described which analyses hydrogen in H{sub 2}S and H{sub 2}O in the same way. (author) [French] Un four a uranium est insere dans la ligne d'introduction de gaz d'un spectrometre de masse entre la fuite et la source. La ligne est alimentee par des composes hydrogenes simples (H{sub 2}O, NH{sub 3}, H{sub 2}S) qui sont de cette facon transformes en hydrogene gazeux. On evite dans une large mesure les effets de memoire en chauffant la ligne de l'echantillon jusqu'a 90 deg. C. La vitesse de l'analyse isotopique est seulement legerement inferieure a celle de l'hydrogene gazeux lui-meme; la precision est meilleure du fait de la reduction des effets de fractionnement dans la fuite. Pour les mesures absolues du deuterium dans l'eau, la presence de H{sub 3}{sup +} pose un probleme. Les echantillons d'eau, prepares en melangeant un echantillon inconnu d'eau legere a differentes quantites d'eau lourde, sont equilibres par de l'hydrogene sulfure et l'analyse de

  5. Challenges and recent advances in mass spectrometric imaging of neurotransmitters

    Science.gov (United States)

    Gemperline, Erin; Chen, Bingming; Li, Lingjun

    2014-01-01

    Mass spectrometric imaging (MSI) is a powerful tool that grants the ability to investigate a broad mass range of molecules, from small molecules to large proteins, by creating detailed distribution maps of selected compounds. To date, MSI has demonstrated its versatility in the study of neurotransmitters and neuropeptides of different classes toward investigation of neurobiological functions and diseases. These studies have provided significant insight in neurobiology over the years and current technical advances are facilitating further improvements in this field. neurotransmitters, focusing specifically on the challenges and recent Herein, we advances of MSI of neurotransmitters. PMID:24568355

  6. Photometric and emission-spectrometric determination of boron in steels

    International Nuclear Information System (INIS)

    Thierig, D.

    1982-01-01

    A method for the photometric determination of boron in unalloyed and alloyed steels is described, in which Curcumine is used as reagent. A separation of boron is not necessary. Limit of detection: 0.0003% B. The decomposition of boron nitride in the steel is achieved by heating the whole sample in fuming sulphuric acid/phosphoric acid. For the emission spectrometric investigation of solid steel samples and for the spectrochemical analysis of solutions with plasma excitation working parameters are given and possibilities of interferences are demonstrated. (orig.) [de

  7. Mass spectrometric study of Nd2S3 vaporization

    International Nuclear Information System (INIS)

    Fenochka, B.V.

    1987-01-01

    The authors conduct a mass-spectrometric study of neodymium(III) sulfide vaporization. The chemical composition of the samples was stoichiometric and the samples were vaporized from tantalum effusion cells. When the vapor over Nd 2 S 3 is ionized by electrons the mass spectra shows monovalent cations of Nd, S, NdS, and NdO. The enthalpy of vaporization if Nd atoms from Nd 2 S 3 at average experimental temperatures and the standard enthalpy of reaction is shown. Also presented is the enthalpy of vaporization of NdS molecules from Nd 2 S 3 at average experimental temperatures and the standard enthalpy of reaction

  8. Gamma spectrometric analyses of environmental samples at PINSTECH

    International Nuclear Information System (INIS)

    Faruq, M.U.; Parveen, N.; Ahmed, B.; Aziz, A.

    1979-01-01

    Gamma spectrometric analyses of air and other environmental samples from PINSTECH were carried out. Air particulate samples were analyzed by a Ge(Li) detector on a computer-based multichannel analyzer. Other environmental samples were analyzed by a Na(T1) scintillation detector spectrometer and a multichannel analyzer with manual analysis. Concentration of radionuclides in the media was determined and the sources of their production were identified. Age of the fall out was estimated from the ratios of the fission products. (authors)

  9. Mass spectrometric investigation of fluorated europium. beta. -diketonates. [Electrons

    Energy Technology Data Exchange (ETDEWEB)

    Khomenko, V.S.; Lozinskij, M.O.; Fialkov, Yu.A.; Rasshinina, T.A.; Suboch, V.P. (AN Belorusskoj SSR, Minsk. Inst. Fiziki; AN Ukrainskoj SSR, Kiev. Inst. Organicheskoj Khimii)

    Ternary complexes of europium with two organic ligands - fluorated ..beta..-diketone and organic base - in the aqueous phase at electron shock are investigated; regroupings that take place in them are established. Mass-spectrometric investigation has shown that complexes with ..beta..-diketones, containing in oxygen atom in a fluorated radical, eliminate stable molecules of difluorophosgen, CoF/sub 2/. For the complexes studied under the above conditions the Co molecule elimination is also typical which is accompanied by the formation of ions with a metal-carbon bond.

  10. Mass spectrometric investigation of fluorated europium β-diketonates

    International Nuclear Information System (INIS)

    Khomenko, V.S.; Lozinskij, M.O.; Fialkov, Yu.A.; Rasshinina, T.A.; Suboch, V.P.; AN Ukrainskoj SSR, Kiev. Inst. Organicheskoj Khimii)

    1983-01-01

    Ternary complexes of europium with two organic lidands - fluorated β-diketone and organic base - in the aqueous phase at electron shock are investigated; regroupings that take place in them are established. Mass-spectrometric investigation has shown that complexes with β-diketones, containing in oxygen atom in a fluorated radical, eliminate stable molecules of difluorophosgen, CoF 2 . For the complexes studied under the above conditions the Co molecule elimination is also typical which is accompanied by the formation of ions with a metal-carbon bond

  11. Thermogravimetric-quadrupole mass-spectrometric analysis of geochemical samples.

    Science.gov (United States)

    Gibson, E. K., Jr.; Johnson, S. M.

    1972-01-01

    Thermogravimetric-quadrupole mass-spectrometric-analysis techniques can be used to study a wide variety of problems involving decomposition processes and identification of released volatile components. A recording vacuum thermoanalyzer has been coupled with a quadrupole mass spectrometer. The rapid scan capabilities of the quadrupole mass spectrometer are used to identify the gaseous components released. The capability of the thermogravimetric-quadrupole mass spectrometer to provide analytical data for identification of the released volatile components, for determination of their sequence of release and for correlation of thermal-decomposition studies is illustrated by an analysis of the Orgueil carbonaceous chondrite.

  12. Determination of uranium enrichment by using gamma-spectrometric methods

    International Nuclear Information System (INIS)

    Kutnyj, D.V.; Telegin, Yu.N.; Odejchuk, N.P.; Mikhailov, V.A.; Tovkanets, V.E.

    2009-01-01

    By using commercial analysis programs MGAU (LLNL, USA) and FRAM (LANL, USA) the summary error of gamma-spectrometric uranium enrichment measurements was investigated. Uranium samples with enrichments of 0,71; 4,46 and 20,1 % were measured. The coaxial high purity germanium detector (type GC) and the planar germanium detector (type LEGe) were used as gamma-radiation detectors. It was shown that experimental equipment and mathematical software available in NSC KIPT allow us to measure uranium enrichment by nondestructive method with accuracy of not worse than 2%.

  13. Enzyme-based Colorimetric and Potentiometric Biosensor for Detecting Pb (II Ions in Milk

    Directory of Open Access Journals (Sweden)

    Hardeep Kaur

    2014-08-01

    Full Text Available The aim of the present work was to study a simple colorimetric and potentiometric biosensor based on urease inhibition by Pb (II ions for its estimation in milk samples. Urease immobilized on nylon membrane by hydrosol gel method was used as the biocomponent to demonstrate the metal effect on the enzyme activity using phenol red as the pH indicator. A lower limit detection of 38.6µm was achieved in the milk and the enzyme membranes were stable for more than two months at 4ºC. In potentiometric approach, response of an ion selective electrode (ISE to changing ammonium ion concentration as a consequence of urease inhibition by Pb (II ions was explored to achieve a detection limit of 9.66 µm. Lead specificity was attained by means of masking agents 1,10 - phenanthroline and sodium potassium tartarate. Validation of the developed biosensors was carried out with spiked milk samples.

  14. Potentiometric Surface of the Magothy Aquifer in Southern Maryland, September 2009

    Science.gov (United States)

    Curtin, Stephen E.; Andreasen, David C.; Staley, Andrew W.

    2010-01-01

    This report presents a map showing the potentiometric surface of the Magothy aquifer in the Magothy Formation of Late Cretaceous age in Southern Maryland during September 2009. The map is based on water-level measurements in 66 wells. The highest measured water level was 85 feet above sea level near the northern boundary and outcrop area of the aquifer in the north-central part of Anne Arundel County. The potentiometric surface declined towards the south. Local hydraulic gradients were directed toward the center of a cone of depression in the Waldorf area that developed in response to pumping. Measured groundwater levels were as low as 71 feet below sea level in the Waldorf area. The map also shows well yield in gallons per day for 2008 at wells or well fields.

  15. Potentiometric Surface of the Magothy Aquifer in Southern Maryland, September 2007

    Science.gov (United States)

    Curtin, Stephen E.; Andreasen, David C.; Staley, Andrew W.

    2009-01-01

    This report presents a map showing the potentiometric surface of the Magothy aquifer in the Magothy Formation of Late Cretaceous age in Southern Maryland during September 2007. The map is based on water-level measurements in 69 wells. The highest measured water level was 85 feet above sea level near the northern boundary and outcrop area of the aquifer in the north-central part of Anne Arundel County. The potentiometric surface declined towards the south. Local gradients were directed toward the center of a cone of depression in the Waldorf area that developed in response to pumping. Measured ground-water levels were as low as 90 feet below sea level in the Waldorf area.

  16. Spectrophotometric, potentiometric, and gravimetric determination of lanthanides with peri-dihydroxynaphthindenone

    International Nuclear Information System (INIS)

    Hassan, S.S.M.; Mahmoud, W.H.

    1982-01-01

    Sensitive and reasonably selective methods are described for the spectrophotometric, potentiometric, and gravimetric determination of lanthanides using peri-dihydroxynaphthindenone as a novel chromogenic and precipitating reagent. The reagent forms a stable 1:2 (metal:reagent) type of complex with light lanthanides at pH 2-7 in 1:1 ethanol-water mixture. Low metal concentrations ( 4 L mol -1 cm -1 ) which obey Beer's law. Quantitative precipitation of the complexes from metal solutions of concentrations > 100 μg/mL permits both gravimetric quantitation by igniting the precipitates to the metal oxides and potentiometric titration of the excess reagent. Results with an average recovery of 98% (standard deviation 0.7%) are obtainable for 0.1 μg to 200 mg of all light lanthanides. Many foreign ions naturally occurring or frequently associated with lanthanides do not interfere or can be tolerated

  17. Determination of binding constants of cyclodextrin inclusion complexes with amino acids and dipeptides by potentiometric titration.

    Science.gov (United States)

    Kahle, Claudia; Holzgrabe, Ulrike

    2004-10-01

    Cyclodextrins are well known for their ability to separate enantiomers of drugs, natural products, and other chiral substances using HPLC, GC, or CE. The resolution of the enantiomers is due to the formation of diastereomeric complexes between the cyclodextrin and the pairs of enantiomers. The aim of this study was to determine the binding constants of the complexes between alpha- and beta-cyclodextrin and the enantiomers of a series of aliphatic and aromatic amino acids, and dipeptides, using a potentiometric titration method. The results of this method are compared to other methods, and correlated to findings in cyclodextrin-modified capillary electrophoresis and possible complex structures. Potentiometric titration was found to be an appropriate tool to determine the binding constants of cyclodextrin inclusion complexes.

  18. Specification analysis of plutonium fuels : a potentiometric method for the determination of plutonium

    International Nuclear Information System (INIS)

    Vaidyanathan, S.; Natarajan, P.R.

    1977-01-01

    A potentiometric method for the routine determination of plutonium in the specification analysis of plutonium fuels is described. Plutonium is oxidized to Pu(VI) with AgO and Pu(VI) is reduced with Fe(II) after the destruction of excess AgO with sulphamic acid. The excess Fe(II) is titrated potentiometrically against K 2 Cr 2 O 7 , the titration being carried out by adding a concentrated titrant solution from a weight burette and a suitably diluted solution from another weight burette near the end. The overall relative standard deviation obtained in 326 analyses of a working standard solution by eight experimenters is 0.14 percent. (author)

  19. Potentiometric titrations of para and nitro substituted aromatic acids and their mixtures in methylethyl ketone

    International Nuclear Information System (INIS)

    Ozeroglu, C.; Karahan, M.

    2011-01-01

    In this study, it was the purpose to examine the potentiometric titrations of para and nitro substituted aromatic acids in methylethyl ketone (MEK) as a non-aqueous solvent. Good analytical results were obtained in determining the amount of each acid and the amounts of acids in their ternary mixtures by using 0.0964 N tetrabuthylammoniumhydroxyde (TBAH) as a standard titrant. Methylethyl ketone (MEK) which is a good solvent for many organic compounds and has a convenient liquid range of -86 to 80 deg. C was used for titration of the para and nitro substituted aromatic acids. A linear relationship has been found between pKa values of the para and nitro substituted aromatic acids in water and the half neutralization potential (HNP) values determined by potentiometric titration curves of the same acids in MEK. (author)

  20. Semi-automatic version of the potentiometric titration method for characterization of uranium compounds

    International Nuclear Information System (INIS)

    Cristiano, Bárbara F.G.; Delgado, José Ubiratan; Wanderley S da Silva, José; Barros, Pedro D. de; Araújo, Radier M.S. de; Dias, Fábio C.; Lopes, Ricardo T.

    2012-01-01

    The potentiometric titration method was used for characterization of uranium compounds to be applied in intercomparison programs. The method is applied with traceability assured using a potassium dichromate primary standard. A semi-automatic version was developed to reduce the analysis time and the operator variation. The standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization and compatible with those obtained by manual techniques. - Highlights: ► A semi-automatic potentiometric titration method was developed for U charaterization. ► K 2 Cr 2 O 7 was the only certified reference material used. ► Values obtained for U 3 O 8 samples were consistent with certified. ► Uncertainty of 0.01% was useful for characterization and intercomparison program.

  1. An on-line potentiometric sequential injection titration process analyser for the determination of acetic acid.

    Science.gov (United States)

    van Staden, J F; Mashamba, Mulalo G; Stefan, Raluca I

    2002-09-01

    An on-line potentiometric sequential injection titration process analyser for the determination of acetic acid is proposed. A solution of 0.1 mol L(-1) sodium chloride is used as carrier. Titration is achieved by aspirating acetic acid samples between two strong base-zone volumes into a holding coil and by channelling the stack of well-defined zones with flow reversal through a reaction coil to a potentiometric sensor where the peak widths were measured. A linear relationship between peak width and logarithm of the acid concentration was obtained in the range 1-9 g/100 mL. Vinegar samples were analysed without any sample pre-treatment. The method has a relative standard deviation of 0.4% with a sample frequency of 28 samples per hour. The results revealed good agreement between the proposed sequential injection and an automated batch titration method.

  2. Potentiometric determination of free nitric-acid in trilaurylamine solutions containing plutonium nitrate

    International Nuclear Information System (INIS)

    Perez, J.J.; Saey, J.C.

    1965-01-01

    A potentiometric method of determination of the free nitric acid in trilaurylamine solutions containing plutonium or thorium nitrates is described. The potentiometric titration is carried out in a mixture of benzene and 1,2-dichloro ethane with a standard solution of trilaurylamine as the titrant. When thorium nitrate is present the metal complex is not dissociated then the titration has a single end-point. In the case of plutonium nitrate the partial dissociation of the plutonium complex corresponds to a second point. The experimental error in duplicate analyses of 50 samples is about 1 per cent for free acid concentrations in the range of 0,03 to 0,1 N and plutonium concentrations between 1 to 5 g/l. (authors) [fr

  3. Improved Performance of the Potentiometric Biosensor for the Determination of Creatinine

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov; Rasmussen, Claus/Dallerup; Zachau-Christiansen, Birgit

    2007-01-01

    The development of potentiometric biosensors for the determination of creatinine is attractive because it is a frequently analysed species in clinical chemistry. Contemporary methods of analysing creatinine engage chemicals harmful to the environment and generate large volumes of waste disposals....... By introducing a membrane-based potentiometric biosensor with immobilised creatinine deaminase, the measurements can be performed by miniaturised portable devices that are easy to handle and allow rapid analysis at a minimum consumption of chemicals. Thus, the enzymatic creatinine biosensors was revisited...... performed by flow injection analysis (FIA) showed that the response time could be lowered to approx. 30 sec. using sample volumes of 30 L. Interferences were corrected for by application of the Nicolsky-Eisenman equation thus allowing determination of creatinine in matrices resembling those of clinical...

  4. Reconstruction of neutron spectra using neural networks starting from the Bonner spheres spectrometric system; Reconstruccion de espectros de neutrones usando redes neuronales a partir del sistema espectrometrico de esferas de Bonner

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz R, J.M.; Martinez B, M.R.; Arteaga A, T.; Vega C, H.R.; Hernandez D, V.M.; Manzanares A, E. [Universidad Autonoma de Zacatecas, A.P. 336, 98000 Zacatecas (Mexico)

    2005-07-01

    The artificial neural networks (RN) have been used successfully to solve a wide variety of problems. However to determine an appropriate set of values of the structural parameters and of learning of these, it continues being even a difficult task. Contrary to previous works, here a set of neural networks is designed to reconstruct neutron spectra starting from the counting rates coming from the detectors of the Bonner spheres system, using a systematic and experimental strategy for the robust design of multilayer neural networks of the feed forward type of inverse propagation. The robust design is formulated as a design problem of Taguchi parameters. It was selected a set of 53 neutron spectra, compiled by the International Atomic Energy Agency, the counting rates were calculated that would take place in a Bonner spheres system, the set was arranged according to the wave form of those spectra. With these data and applying the Taguchi methodology to determine the best parameters of the network topology, it was trained and it proved the same one with the spectra. (Author)

  5. Potentiometric studies on the complexes of tetracycline (TC) and oxytetracycline (OTC) with some metal ions. Potentiometrische Untersuchungen der Komplexe von Tetracyclin (TC) und Oxytetracyclin (OTC) mit einigen Metall-Ionen

    Energy Technology Data Exchange (ETDEWEB)

    Ghandour, M A; Azab, H A; Hassan, A; Ali, A M [Assiut Univ. (Egypt)

    1992-01-01

    The interaction of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Zn(II), Cd(II), Hg(II), Pb(II), Al(III), and UO[sub 2](II) ions with tetracycline (TC) were studied by potentiometric pH titrations. The formation constants of the different binary complexes formed in such systems have been determined at 25[+-]0.1 deg C and [mu]=0.1 moll[sup -1] (NaNO[sub 3]). Potentiometric pH equilibrium measurements have been made under the same conditions for the interaction of oxytetracycline (OTC) and Cu(II), Cd(II), Pb(II), and UO[sub 2](II). The formation of (1:1) binary complexes are inferred from the potentiometric pH titration curves. The protonation constants of TC and OTC were also determined under the same conditions and refined (ESAB2M computer program). The transition metal stability constants are consistent with the Irving-Williams series. (authors).

  6. Potentiometric pKa Determination of Piroxicam and Tenoxicam in Acetonitrile-Water Binary Mixtures

    OpenAIRE

    Çubuk Demiralay, Ebru; Yılmaz, Hülya

    2012-01-01

    Abstract: Ionization constant (pKa) is one among the parameter to be estimated with accuracy, irrespective of solubility constraints. In the present study, acid-base behaviour of the piroxicam and tenoxicam was studied. By using the potentiometric method, pKa values of piroxicam and tenoxicam have been determined in different percentage of acetonitrile-water binary mixtures (acetonitrile content between 30 and 45% in volume). Aqueous pKa values of these compounds were calculated by mole fract...

  7. Potentiometric determination of sulfate with EDTA and the cupric-selective electrode

    International Nuclear Information System (INIS)

    Baumann, E.W.

    1976-11-01

    Sulfate was indirectly determined by precipitating sulfate as BaSO 4 and then dissolving BaSO 4 in excess ammoniacal EDTA. The excess EDTA was titrated potentiometrically with La 3+ . A cupric-selective electrode was used to detect the end point. About 10 -3 M SO 4 2- was determined in 3M HCl solutions of metal oxides with a relative standard deviation of 3.5 percent and a bias of +4 percent

  8. Potentiometric titration of molybdenum (6) with a cathode-polarized solid electrode

    International Nuclear Information System (INIS)

    Boeva, L.V.; Kimstach, V.A.; Bagdasarov, K.N.

    1980-01-01

    The possibility has been studied of using solid electrodes for potentiometric precipitation titration of molybdenum (6). A cathode-polarized electrode, electrochemically covered with a molybdenum blue layer, can be used as indicator electrode. The best results were obtained during deposition of molybdenum blue on a tungsten electrode. The mechanism of electrode work during titration has been investigated. A procedure has been developed of titration of molybdenum (6) in acid solutions using hydroxylamine N-aryl derivatives as titrants

  9. Further investigation on the degree of deacetylation of chitosan determined by potentiometric titration

    OpenAIRE

    Kamal Sweidan; Abdel-Motalleb Jaber; Nawzat Al-jbour; Rana Obaidat; Mayyas Al- Remawi; Adnan Badwan

    2011-01-01

    The degree of deacetylation (DDA) of various low molecular weight chitosan (LMWC) species as the hydrochloride and free base (amine form) was determined by direct and back potentiometric titration, respectively. The DDA values obtained for the chitosan hydrochloride by direct titration were greater than 93% for all oligomers tested (Molecular weight (Mwt) between about 1.3 to 30.0 kDa). However, the DDA values obtained for chitosan amine oligomers using back titration were significantly lower...

  10. Semi-automatic version of the potentiometric titration method for characterization of uranium compounds.

    Science.gov (United States)

    Cristiano, Bárbara F G; Delgado, José Ubiratan; da Silva, José Wanderley S; de Barros, Pedro D; de Araújo, Radier M S; Dias, Fábio C; Lopes, Ricardo T

    2012-09-01

    The potentiometric titration method was used for characterization of uranium compounds to be applied in intercomparison programs. The method is applied with traceability assured using a potassium dichromate primary standard. A semi-automatic version was developed to reduce the analysis time and the operator variation. The standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization and compatible with those obtained by manual techniques. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. The uncertainty evaluation of measurement for uranium in UF_6 hydrolysate by potentiometric titration

    International Nuclear Information System (INIS)

    Jiang Haiying; Cheng Ruoyu; Meng Xiujun

    2014-01-01

    Based on the building of mathematical model, this paper analyzed the origin of component of indeterminacy of which the measurement result for uranium in uranium hexafluoride hydrolysate by potentiometric titration, also each uncertainty was calculated and the expanded uncertainty was given. By evaluation the result of the uranium concentration is that: (158.88 + 1.22) mgU/mL, K = 2, P = 95%. (authors)

  12. Potentiometric studies on ternary complexes involving some divalent transition metal ions, gallic acid and biologically abundant aliphatic dicarboxylic acids in aqueous solutions

    Directory of Open Access Journals (Sweden)

    Abdelatty Mohamed Radalla

    2015-06-01

    Full Text Available Formation of binary and ternary complexes of the divalent transition metal ions, Cu2+, Ni2+, Co2+ and Zn2+ with gallic acid and the biologically important aliphatic dicarboxylic acids (adipic, succinic, malic, malonic, maleic, tartaric and oxalic acids were investigated by means of the potentiometric technique at 25 °C and I = 0.10 mol dm−3 NaNO3. The acid-base properties of the ligands were investigated and discussed. The acidity constants of gallic acid and aliphatic dicarboxylic acids were determined and used for determining the stability constants of the binary and ternary complexes formed in the aqueous medium under the above experimental conditions. The formation of the different 1:1 and 1:2 binary complexes and 1:1:1 ternary complexes are inferred from the corresponding potentiometric pH-metric titration curves. The ternary complex formation was found to occur in a stepwise manner. The stability constants of these binary and ternary systems were calculated. The values of Δ log K, percentage of relative stabilization (%R.S. and log X were evaluated and discussed. The concentration distribution of the various complex species formed in solution was evaluated and discussed. The mode of chelation of ternary complexes formed was ascertained by conductivity measurements.

  13. Potentiometric Surface of the Upper Floridan Aquifer in the St. Johns River Water Management District and Vicinity, May 2008

    Science.gov (United States)

    Kinnaman, Sandra L.; Dixon, Joann F.

    2008-01-01

    This map depicts the potentiometric surface of the Upper Floridan aquifer in the St. Johns River Water Management District and vicinity for May 2008. Potentiometric contours are based on water-level measurements collected at 567 wells during the period May 6-May 27, near the end of the dry season. Some contours are inferred from previous potentiometric-surface maps with larger well networks. The potentiometric surface of the carbonate Upper Floridan aquifer responds mainly to rainfall, and more locally, to ground-water withdrawals and spring flow. Potentiometric-surface highs generally correspond to topographic highs where the aquifer is recharged. Springs and areas of diffuse upward leakage naturally discharge water from the aquifer and are most prevalent along the St. Johns River. Areas of discharge are reflected by depressions in the potentiometric surface. Ground-water withdrawals locally have lowered the potentiometric surface. Ground water in the Upper Floridan aquifer generally flows from potentiometric highs to potentiometric lows in a direction perpendicular to the contours. Measured values of the potentiometric surface ranged from 7 feet below NGVD29 near Fernandina Beach, Florida, to 124 feet above NGVD29 in Polk County, Florida. The average water level of the network in May 2008 was about 1 foot lower than the average in September 2007 following below-average rainfall during the dry season of 2007-08. Seasonal differences in network average water levels generally range from 4 to 6 feet. For 457 wells with previous measurements, May 2008 levels ranged from about 19 feet below to about 11 feet above September 2007 water levels. The average water level of the network in May 2008 was about 1 foot higher than the average in May 2007. For 544 wells with previous measurements, May 2008 levels ranged from about 8 feet below to about 13 feet above May 2007 water levels. Long-term hydrographs of ground-water levels for continuous and periodic wells are available

  14. Design and evaluation of potentiometric principles for bladder volume monitoring: a preliminary study.

    Science.gov (United States)

    Chen, Shih-Ching; Hsieh, Tsung-Hsun; Fan, Wen-Jia; Lai, Chien-Hung; Chen, Chun-Lung; Wei, Wei-Feng; Peng, Chih-Wei

    2015-06-01

    Recent advances in microelectronics and wireless transmission technology have led to the development of various implantable sensors for real-time monitoring of bladder conditions. Although various sensing approaches for monitoring bladder conditions were reported, most such sensors have remained at the laboratory stage due to the existence of vital drawbacks. In the present study, we explored a new concept for monitoring the bladder capacity on the basis of potentiometric principles. A prototype of a potentiometer module was designed and fabricated and integrated with a commercial wireless transmission module and power unit. A series of in vitro pig bladder experiments was conducted to determine the best design parameters for implementing the prototype potentiometric device and to prove its feasibility. We successfully implemented the potentiometric module in a pig bladder model in vitro, and the error of the accuracy of bladder volume detection was design principles and animal experience gathered from this research can serve as a basis for developing new implantable bladder sensors in the future.

  15. Screen-printed sensor for batch and flow injection potentiometric chromium(VI) monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Moreno, Raul A.; Gismera, M.J.; Sevilla, M.T.; Procopio, Jesus R. [Facultad de Ciencias, Universidad Autonoma de Madrid, Departamento de Quimica Analitica y Analisis Instrumental, Madrid (Spain)

    2010-05-15

    A disposable screen-printed electrode was designed and evaluated for direct detection of chromium(VI) in batch and flow analysis. The carbon screen-printed electrode was modified with a graphite-epoxy composite. The optimal graphite-epoxy matrix contains 37.5% graphite powder, 12.5% diphenylcarbohydrazide, a selective compound for chromium(VI), and 50% epoxy resin. The principal analytical parameters of the potentiometric response in batch and flow analysis were optimized and calculated. The screen-printed sensor exhibits a response time of 20 {+-} 1 s. In flow analysis, the analytical frequency of sampling is 70 injections per hour using 0.1 M NaNO{sub 3} solution at pH 3 as the carrier, a flow rate of 2.5 mL.min{sup -1}, and an injection sample volume of 0.50 mL. The sensor shows potentiometric responses that are very selective for chromium(VI) ions and optimal detection limits in both static mode (2.1 x 10{sup -7} M) and online analysis (9.4 x 10{sup -7} M). The disposable potentiometric sensor was employed to determine toxicity levels of chromium(VI) in mineral, tap, and river waters by flow-injection potentiometry and batch potentiometry. Chromium(VI) determination was also carried out with successful results in leachates from municipal solid waste landfills. (orig.)

  16. Potentiometric application of boron- and phosphorus-doped glassy carbon electrodes

    Directory of Open Access Journals (Sweden)

    ZORAN V. LAUSEVIC

    2001-03-01

    Full Text Available Acomparative study was carried out of the potentiometric application of boronand phosphorus-doped and undoped glassy carbon samples prepared at the same heat treatment temperature (HTT 1000°C. The electrochemical activities of the obtained electrode materials were investigated on the example of argentometric titrations. It was found that the electrochemical behaviour of the doped glassy carbon samples are very similar to a Sigri (undoped glassy carbon sample (HTT 2400°C. The experiments showed that the potentiometric response depends on the polarization mode, the nature of the sample, the pretreatment of the electrode surface, and the nature of the supporting electrolyte. The amounts of iodide, bromide, and of chloridewere determined to be 1.27 mg, 0.80 mg and 0.54 mg, respectively, with a maximum relative standard deviation of less than 1.1%. The obtained results are in good agreement with the results of comparative potentiometric titrations using a silver indicator electrode. The titrationmethod was applied to the indirect determination of pyridoxine hydrochloride, i.e., vitamin B6.

  17. Urea potentiometric enzymatic biosensor based on charged biopolymers and electrodeposited polyaniline.

    Science.gov (United States)

    Lakard, Boris; Magnin, Delphine; Deschaume, Olivier; Vanlancker, Guilhem; Glinel, Karine; Demoustier-Champagne, Sophie; Nysten, Bernard; Jonas, Alain M; Bertrand, Patrick; Yunus, Sami

    2011-06-15

    A potentiometric biosensor based on urease was developed for the quantitative determination of urea concentration in aqueous solutions for biomedical applications. The urease was either physisorbed onto an electrodeposited polyaniline film (PANI), or immobilized on a layer-by-layer film (LbL) assembled over the PANI film, that was obtained by the alternate deposition of charged polysaccharides (carboxymethylpullulan (CMP) and chitosan (CHI)). In the latter case, the urease (Urs) enzyme was either physically adsorbed or covalently grafted to the LbL film using carbodiimide coupling reaction. Potentiometric responses of the enzymatic biosensors were measured as a function of the urea concentration in aqueous solutions (from 10(-6) to 10(-1) mol L(-1) urea). Very high sensitivity and short response time were observed for the present biosensor. Moreover, a stability study showed a higher stability over time for the potentiometric response of the sensor with the enzyme-grafted LbL film, testifying for the protective nature of the polysaccharide coating and the interest of covalent grafting. Copyright © 2011 Elsevier B.V. All rights reserved.

  18. Molecular dynamics simulation of potentiometric sensor response: the effect of biomolecules, surface morphology and surface charge.

    Science.gov (United States)

    Lowe, B M; Skylaris, C-K; Green, N G; Shibuta, Y; Sakata, T

    2018-05-10

    The silica-water interface is critical to many modern technologies in chemical engineering and biosensing. One technology used commonly in biosensors, the potentiometric sensor, operates by measuring the changes in electric potential due to changes in the interfacial electric field. Predictive modelling of this response caused by surface binding of biomolecules remains highly challenging. In this work, through the most extensive molecular dynamics simulation of the silica-water interfacial potential and electric field to date, we report a novel prediction and explanation of the effects of nano-morphology on sensor response. Amorphous silica demonstrated a larger potentiometric response than an equivalent crystalline silica model due to increased sodium adsorption, in agreement with experiments showing improved sensor response with nano-texturing. We provide proof-of-concept that molecular dynamics can be used as a complementary tool for potentiometric biosensor response prediction. Effects that are conventionally neglected, such as surface morphology, water polarisation, biomolecule dynamics and finite-size effects, are explicitly modelled.

  19. Pulsating potentiometric titration technique for assay of dissolved oxygen in water at trace level.

    Science.gov (United States)

    Sahoo, P; Ananthanarayanan, R; Malathi, N; Rajiniganth, M P; Murali, N; Swaminathan, P

    2010-06-11

    A simple but high performance potentiometric titration technique using pulsating sensors has been developed for assay of dissolved oxygen (DO) in water samples down to 10.0 microg L(-1) levels. The technique involves Winkler titration chemistry, commonly used for determination of dissolved oxygen in water at mg L(-1) levels, with modification in methodology for accurate detection of end point even at 10.0 microg L(-1) levels DO present in the sample. An indigenously built sampling cum pretreatment vessel has been deployed for collection and chemical fixing of dissolved oxygen in water samples from flowing water line without exposure to air. A potentiometric titration facility using pulsating sensors developed in-house is used to carry out titration. The power of the titration technique has been realised in estimation of very dilute solution of iodine equivalent to 10 microg L(-1) O(2). Finally, several water samples containing dissolved oxygen from mg L(-1) to microg L(-1) levels were successfully analysed with excellent reproducibility using this new technique. The precision in measurement of DO in water at 10 microg L(-1) O(2) level is 0.14 (n=5), RSD: 1.4%. Probably for the first time a potentiometric titration technique has been successfully deployed for assay of dissolved oxygen in water samples at 10 microg L(-1) levels. Copyright 2010 Elsevier B.V. All rights reserved.

  20. Pulsating potentiometric titration technique for assay of dissolved oxygen in water at trace level

    International Nuclear Information System (INIS)

    Sahoo, P.; Ananthanarayanan, R.; Malathi, N.; Rajiniganth, M.P.; Murali, N.; Swaminathan, P.

    2010-01-01

    A simple but high performance potentiometric titration technique using pulsating sensors has been developed for assay of dissolved oxygen (DO) in water samples down to 10.0 μg L -1 levels. The technique involves Winkler titration chemistry, commonly used for determination of dissolved oxygen in water at mg L -1 levels, with modification in methodology for accurate detection of end point even at 10.0 μg L -1 levels DO present in the sample. An indigenously built sampling cum pretreatment vessel has been deployed for collection and chemical fixing of dissolved oxygen in water samples from flowing water line without exposure to air. A potentiometric titration facility using pulsating sensors developed in-house is used to carry out titration. The power of the titration technique has been realised in estimation of very dilute solution of iodine equivalent to 10 μg L -1 O 2 . Finally, several water samples containing dissolved oxygen from mg L -1 to μg L -1 levels were successfully analysed with excellent reproducibility using this new technique. The precision in measurement of DO in water at 10 μg L -1 O 2 level is 0.14 (n = 5), RSD: 1.4%. Probably for the first time a potentiometric titration technique has been successfully deployed for assay of dissolved oxygen in water samples at 10 μg L -1 levels.

  1. Determination of lithium in organic matrix by potentiometric titration using fluoride ion selective electrode

    International Nuclear Information System (INIS)

    Govindan, R.; Alamelu, D.; Shah, Raju; Aggarwal, S.K.

    2008-01-01

    A method has been developed for the determination of lithium (Li) present in organic matrix containing hexa methylene tetramine (HMTA) and urea used in the sol-gel process for preparing lithium titanate microspheres, using fluoride ion selective electrode and potentiometric end point. Lithium is present in the wash solutions of the Sol-Gel process employed for the preparation of lithium titanate microspheres, proposed to be used in TBM (Test Blanket Module) of International Thermonuclear Experimental Reactor (ITER) project. Methods such as ICP-AES, AAS etc. used in aqueous solutions cannot be employed directly for lithium determination in organic matrix containing hexa methylene tetramine (HMTA), urea, NH 4 NO 3 , NH 4 Cl etc. A potentiometric method using a combination fluoride ion selective electrode for end point detection was developed and has been employed for lithium determination in the process streams from sol-gel process. The method is simple and rapid and an accuracy of about 0.5 % was achieved for the determination of Li in the range of 1 to 20 mg. The method is based on the complexation of Li by adding a known excess of NH 4 F solution, followed by potentiometric end point detection using fluoride ISE

  2. Stripping potentiometric analysis: application to determination of metallic cations in presence of uranium

    International Nuclear Information System (INIS)

    Pereira-Ramos, J.P.; Chivot, J.; Sarantopoulos, F.; Godard, R.

    1984-01-01

    Potentiometric stripping analysis consists of a potentiostatic deposition step of trace elements and a subsequent stripping step. The trace metals are simultaneously reduced at a rotating electrode, the working electrode being a mercury film coated glassy carbon electrode; the amalgamated metals are then re-oxidized with an oxidizing agent. The analytical signal of this method is the time required for complete re-oxidation. Influence of different parameters on the analytical signal is studied by using mercury (II) ions as oxidizing agent in 5.10 -4 M H 2 SO 4 aqueous solution. Here, we point out the main characteristics of the potentiometric stripping analysis under the same experimental conditions. The reproductibility ranges are comprised between 0.5% to 1.5% and the detection limit for cadmium (II) is estimated to be 2.10 -10 M with a plating time of 300 seconds. Small quantities, as 10 -7 M Cd 2+ , Pb 2+ and Zn 2+ are simultaneously determined in presence of U (VI) ions (UO 2 2+ ) with an accuracy of 0.5% for Cd 2+ and Zn 2+ , and 4.5% for Pb 2+ . Compared to well-known electrochemical techniques, potentiometric stripping analysis appears to be a performing method for trace analysis in a wide range of media: this method permits the analysis of elements in presence of species more concentrated and being able to oxidize the trace elements [fr

  3. Separation Techniques for Uranium and Plutonium at Trace Levels for the Thermal Ionization Mass Spectrometric Determination

    International Nuclear Information System (INIS)

    Suh, M. Y.; Han, S. H.; Kim, J. G.; Park, Y. J.; Kim, W. H.

    2005-12-01

    This report describes the state of the art and the progress of the chemical separation and purification techniques required for the thermal ionization mass spectrometric determination of uranium and plutonium in environmental samples at trace or ultratrace levels. Various techniques, such as precipitation, solvent extraction, extraction chromatography, and ion exchange chromatography, for separation of uranium and plutonium were evaluated. Sample preparation methods and dissolution techniques for environmental samples were also discussed. Especially, both extraction chromatographic and anion exchange chromatographic procedures for uranium and plutonium in environmental samples, such as soil, sediment, plant, seawater, urine, and bone ash were reviewed in detail in order to propose some suitable methods for the separation and purification of uranium and plutonium from the safeguards environmental or swipe samples. A survey of the IAEA strengthened safeguards system, the clean room facility of IAEA's NWAL(Network of Analytical Laboratories), and the analytical techniques for safeguards environmental samples was also discussed here

  4. Characterisation of radioactive contaminated materials by combined radiometric and spectrometric methods

    International Nuclear Information System (INIS)

    Dulama, C.; Toma, A.; Dobrin, R.; Ciocîrlan, C.; Stoica, S.; Valeca, M.; Popescu, I. I.

    2013-01-01

    In the present paper, a combined analytical methodology is described, for characterization of radioactive contaminated materials. The subject of testing activities was a set of solutions provided by the Cernavoda NPP, which are originating from processes of radiological survey of workplaces in the plant. In the introduction section, a theoretical approach was given to the origin and nature of main radionuclides occurring in the primary cooling system of the nuclear power plant, with the aim to establish selection criteria and performance requirements for the analytical methods to be used in the development of the characterization methodology. A combination of radiometric and spectrometric methods was selected, based on gross beta counting, high resolution gamma-ray spectrometry and liquid scintillation counting. (authors)

  5. Mass spectrometric 230Th-234U-238U dating of the Devils Hole calcite vein

    International Nuclear Information System (INIS)

    Ludwig, K.R.; Simmons, K.R.; Szabo, B.J.; Riggs, A.C.; Winograd, I.J.; Landwehr, J.M.; Hoffman, R.J.

    1992-01-01

    The Devils Hole calcite vein contains a long-term climatic record, but requires accurate chronologic control for its interpretation. Mass-spectrometric U-series ages for samples from core DH-11 yielding 230 Th ages with precisions ranging from less than 1,000 years (2σ) for samples younger than ∼140 ka (thousands of years ago) to less than 50,000 years for the oldest samples (∼566 ka). The 234 U/ 238 U ages could be determined to a precision of ∼20,000 years for all ages. Calcite accumulated continuously from 566 ka until ∼60 ka at an average rate of 0.7 millimeter per 10 3 years. The precise agreement between replicate analyses and the concordance of the 230 Th/ 238 U and 234 U/ 238 U ages for the oldest samples indicate that the DH-11 samples were closed systems and validate the dating technique in general

  6. Separation Techniques for Uranium and Plutonium at Trace Levels for the Thermal Ionization Mass Spectrometric Determination

    Energy Technology Data Exchange (ETDEWEB)

    Suh, M. Y.; Han, S. H.; Kim, J. G.; Park, Y. J.; Kim, W. H

    2005-12-15

    This report describes the state of the art and the progress of the chemical separation and purification techniques required for the thermal ionization mass spectrometric determination of uranium and plutonium in environmental samples at trace or ultratrace levels. Various techniques, such as precipitation, solvent extraction, extraction chromatography, and ion exchange chromatography, for separation of uranium and plutonium were evaluated. Sample preparation methods and dissolution techniques for environmental samples were also discussed. Especially, both extraction chromatographic and anion exchange chromatographic procedures for uranium and plutonium in environmental samples, such as soil, sediment, plant, seawater, urine, and bone ash were reviewed in detail in order to propose some suitable methods for the separation and purification of uranium and plutonium from the safeguards environmental or swipe samples. A survey of the IAEA strengthened safeguards system, the clean room facility of IAEA's NWAL(Network of Analytical Laboratories), and the analytical techniques for safeguards environmental samples was also discussed here.

  7. Thermodynamic properties over (Ni{sub 2}Te{sub 3}O{sub 8} + NiTe{sub 2}O{sub 5}) in the Ni-Te-O system. Transpiration thermogravimetric and Knudsen effusion mass spectrometric studies

    Energy Technology Data Exchange (ETDEWEB)

    Narasimhan, Tiruppatur Subramaniam Lakshmi; Nalini, Seshadreesan; Manikandan, Palraj; Trinadh, Vinjavarapu Venkata [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Fuel Chemistry Div.; Baba, Magapu Sai [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Resources Management Group

    2016-02-15

    Vaporisation studies over (Ni{sub 2}Te{sub 3}O{sub 8} + NiTe{sub 2}O{sub 5}) in the Ni-Te-O system were carried out by means of transpiration thermogravimetry (TTG) and Knudsen effusion mass spectrometry (KEMS) in the temperature ranges of 950 - 1 060 K and 850 - 950 K respectively. The transpiration measurements were performed for the first time. Comparison of total pressures obtained by TTG with that deduced using partial pressures of vaporising species from KEMS showed a good agreement providing reliable vapour pressures over this phase region. From vapour pressures, enthalpies of solid-gas and gas-phase equilibria and subsequently enthalpy and Gibbs free energies of formation of NiTe{sub 2}O{sub 5}(s) were derived. A thermochemical calculation was performed to assess the possibility of formation of the ternary NiTe{sub 2}O{sub 5}(s) phase on stainless steel clad of mixed-oxide fuelled fast breeder nuclear reactors.

  8. Quantitative mass-spectrometric analysis of hydrogen helium isotope mixtures

    International Nuclear Information System (INIS)

    Langer, U.

    1998-12-01

    This work deals with the mass-spectrometric method for the quantitative analysis of hydrogen-helium-isotope mixtures, with special attention to fusion plasma diagnostics. The aim was to use the low-resolution mass spectrometry, a standard measuring method which is well established in science and industry. This task is solved by means of the vector mass spectrometry, where a mass spectrum is repeatedly measured, but with stepwise variation of the parameter settings of a quadruple mass spectrometer. In this way, interfering mass spectra can be decomposed and, moreover, it is possible to analyze underestimated mass spectra of complex hydrogen-helium-isotope mixtures. In this work experimental investigations are presented which show that there are different parameters which are suitable for the UMS-method. With an optimal choice of the parameter settings hydrogen-helium-isotope mixtures can be analyzed with an accuracy of 1-3 %. In practice, a low sensitivity for small helium concentration has to be noted. To cope with this task, a method for selective hydrogen pressure reduction has been developed. Experimental investigations and calculations show that small helium amounts (about 1 %) in a hydrogen atmosphere can be analyzed with an accuracy of 3 - 10 %. Finally, this work deals with the effects of the measuring and calibration error on the resulting error in spectrum decomposition. This aspect has been investigated both in general mass-spectrometric gas analysis and in the analysis of hydrogen-helium-mixtures by means of the vector mass spectrometry. (author)

  9. Spectrometric properties and radiation damage of BGO crystals

    Science.gov (United States)

    Kim, Gen C.; Gasanov, Eldar M.

    1997-07-01

    Spectrometric properties, such as light output, energy resolution BGO crystals before and after (superscript 60)Co gamma-ray (dose 10(superscript 4) - 10(superscript 6) R) and neutron irradiation (fluence 10(superscript 14) cm(superscript -2)) are investigated. Condition for degradation of spectrometric properties and their recovering after irradiation are studied. The energy spectrum of the photons emitted from BGO crystals irradiated with neutron fluence contains the long living background peak which is caused by self-irradiation with radioactive isotopes produced in the crystals. The defect production was studied in crystals under the high dose gamma-irradiation with (superscript 60)Co isotope. It was found that after doses above 10(superscript 8) R the color center at 365 nm and doses higher than 10(superscript 9) R a wide absorption band in the region of 300 - 350 nm occur. Comparison of these results with those of reactor irradiation has shown that under the high dose gamma-irradiation the structure defect production takes place.

  10. Potentiometric sensing of nuclease activities and oxidative damage of single-stranded DNA using a polycation-sensitive membrane electrode.

    Science.gov (United States)

    Ding, Jiawang; Qin, Wei

    2013-09-15

    A simple, general and label-free potentiometric method to measure nuclease activities and oxidative DNA damage in a homogeneous solution using a polycation-sensitive membrane electrode is reported. Protamine, a linear polyionic species, is used as an indicator to report the cleavage of DNA by nucleases such as restriction and nonspecific nucleases, and the damage of DNA induced by hydroxyl radicals. Measurements can be done with a titration mode or a direct detection mode. For the potentiometric titration mode, the enzymatic cleavage dramatically affects the electrostatical interaction between DNA and protamine and thus shifts the response curve for the potentiometric titration of the DNA with protamine. Under the optimized conditions, the enzyme activities can be sensed potentiometrically with detection limits of 2.7×10(-4)U/µL for S1 nuclease, and of 3.9×10(-4)U/µL for DNase I. For the direct detection mode, a biocomplex between protamine and DNA is used as a substrate. The nuclease of interest cleaves the DNA from the protamine/DNA complex into smaller fragments, so that free protamine is generated and can be detected potentiometrically via the polycation-sensitive membrane electrode. Using a direct measurement, the nuclease activities could be rapidly detected with detection limits of 3.2×10(-4)U/µL for S1 nuclease, and of 4.5×10(-4)U/µL for DNase I. Moreover, the proposed potentiometric assays demonstrate the potential applications in the detection of hydroxyl radicals. It is anticipated that the present potentiometric strategy will provide a promising platform for high-throughput screening of nucleases, reactive oxygen species and the drugs with potential inhibition abilities. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Development of spectrometric probes for emergency preparedness. Status and way forward; Entwicklung von spektrometrierenden Sonden fuer den Notfallschutz. Stand und Perspektiven

    Energy Technology Data Exchange (ETDEWEB)

    Zaehringer, M.; Bleher, M. [Bundesamt fuer Strahlenschutz (BfS), Salzgitter (Germany); Dambacher, M. [X-Ray Imaging Europe, Freiburg (Germany); and others

    2014-01-20

    Spectrometric probes with medium energy resolution (NaI, LaBr{sub 3}, CZT) have the potential to enhance existing gamma dose rate monitoring networks as a early warning system by increasing the sensitivity and specificity. In an emergency situation nuclide specific information with sufficient spatial resolution can be made available to decision makers. An ongoing research project between BfS and the Freiburg Material Research Centre (FMF) aims at the development of semiconductor detectors based on Cadmium-Zink-Telluride which can be used for low cost ruggedized spectrometric systems suitable for deployment in an environmental network. The new probe contains also a newly developed versatile multi channel analyser. The system has a modular design and is based - where ever possible - on open source components. It is complemented by specific analysis software using established data exchange formats. This facilitates international cooperation and exploits synergies through distributed development of components.

  12. Decoupling optical and potentiometric band gaps in pi-conjugated materials.

    Science.gov (United States)

    Susumu, Kimihiro; Therien, Michael J

    2002-07-24

    Syntheses, optical spectroscopy, potentiometric studies, and electronic structural calculations are reported for two classes of conjugated (porphinato)metal oligomers that feature a meso-to-meso ethyne-bridged linkage topology. One set of these systems, bis[(5,5'-10,20-bis[3,5-bis(3,3-dimethyl-1-butyloxy)phenyl]porphinato)zinc(II)]ethyne (DD), 5,15-bis[[5'-10',20'-bis[3,5-di(3,3-dimethyl-1-butyloxy)phenyl]porphinato)zinc(II)]ethynyl]-10,20-bis[3,5-di(9-methoxy-1,4,7-trioxanonyl)phenyl]porphinato)zinc(II) (DDD), and 5,15-bis[[15' '-(5'-10',20'-bis[3,5-bis(3,3-dimethyl-1-butyloxy)phenyl]porphinato)zinc(II)]-[(5' '-10' ',20' '-bis[3,5-di(9-methoxy-1,4,7-trioxanonyl)phenyl]porphinato)zinc(II)]ethyne]ethynyl]-10,20-bis[3,5-di(9-methoxy-1,4,7-trioxanonyl)phenyl]porphinato)zinc(II) (DDDDD), constitute highly soluble analogues of previously studied examples of this structural motif having simple 10,20-diaryl substituents, while a corresponding set of conjugated oligomers, [(5-10,20-bis[3,5-bis(3,3-dimethyl-1-butyloxy)phenyl]porphinato)zinc(II)]-[(5'-15'-ethynyl-10',20'-bis[10,20-bis(heptafluoropropyl)porphinato)zinc(II)]ethyne (DA), 5,15-bis[[5'-10',20'-bis[3,5-di(3,3-dimethyl-1-butyloxy)phenyl]porphinato)zinc(II)]ethynyl]-10,20-bis(heptafluoropropyl)porphinato]zinc(II) (DAD), and 5,15-bis[[15' '-(5'-10',20'-bis[3,5-bis(3,3-dimethyl-1-butyloxy)phenyl]porphinato)zinc(II)]-[(5' '-(10' ',20' '-bis(heptafluoropropyl)porphinato)zinc(II)]ethyne]ethynyl]-10,20-bis[3,5-di(9-methoxy-1,4,7-trioxanonyl)phenyl]porphinato)zinc(II) (DADAD), features alternating electron-rich and electron-poor (porphinato)zinc(II) units. Electrooptic and computational data for these species demonstrate that it is possible to engineer conjugated oligomeric structures that possess highly delocalized singlet (S1) excited states yet manifest apparent one-electron oxidation and reduction potentials (E1/20/+ and E1/2-/0 values) that are essentially invariant with respect to those elucidated for their

  13. Potentiometric Sensor for Real-Time Monitoring of Multivalent Ion Concentrations in Molten Salt

    International Nuclear Information System (INIS)

    Zink, Peter A.; Jue, Jan-Fong; Serrano, Brenda E.; Fredrickson, Guy L.; Cowan, Ben F.; Herrmann, Steven D.; Li, Shelly X.

    2010-01-01

    Electrorefining of spent metallic nuclear fuel in high temperature molten salt systems is a core technology in pyroprocessing, which in turn plays a critical role in the development of advanced fuel cycle technologies. In electrorefining, spent nuclear fuel is treated electrochemically in order to effect separations between uranium, noble metals, and active metals, which include the transuranics. The accumulation of active metals in a lithium chloride-potassium chloride (LiCl-KCl) eutectic molten salt electrolyte occurs at the expense of the UCl3-oxidant concentration in the electrolyte, which must be periodically replenished. Our interests lie with the accumulation of active metals in the molten salt electrolyte. The real-time monitoring of actinide concentrations in the molten salt electrolyte is highly desirable for controlling electrochemical operations and assuring materials control and accountancy. However, real-time monitoring is not possible with current methods for sampling and chemical analysis. A new solid-state electrochemical sensor is being developed for real-time monitoring of actinide ion concentrations in a molten salt electrorefiner. The ultimate function of the sensor is to monitor plutonium concentrations during electrorefining operations, but in this work gadolinium was employed as a surrogate material for plutonium. In a parametric study, polycrystalline sodium beta double-prime alumina (Na-β(double p rime)-alumina) discs and tubes were subject to vapor-phase exchange with gadolinium ions (Gd3+) using a gadolinium chloride salt (GdCl3) as a precursor to produce gadolinium beta double-prime alumina (Gd-β(double p rime)-alumina) samples. Electrochemical impedance spectroscopy and microstructural analysis were performed on the ion-exchanged discs to determine the relationship between ion exchange and Gd3+ ion conductivity. The ion-exchanged tubes were configured as potentiometric sensors in order to monitor real-time Gd3+ ion concentrations in

  14. Knudsen cell mass spectrometric study of the Cs2IOH(g) molecule thermodynamics

    International Nuclear Information System (INIS)

    Roki, F-Z.; Ohnet, M-N.; Fillet, S.; Chatillon, C.; Nuta, I.

    2013-01-01

    Highlights: • The pronounced ionic character leads to only dissociative ionization processes. • Ions formed are same as those coming from pure dimmers. • De-convolution of the ions origin needs accurate thermodynamic values for the pure gas phase. • Mass spectrometric interpretation has to be performed gradually and as a function of suitable condensed compositions. • Thermal functions have to be fully estimated. -- Abstract: The gas phase of the CsI + CsOH system is analyzed by high temperature Knudsen cell mass spectrometry in order to confirm the existence of the Cs 2 IOH(g) complex molecule. The mass spectrometric analysis is quite complex since such molecules undergo dissociative ionization into fragment ions that mix with the same ions from dimers of the pure compounds in the same vapor phase. Varying the chemical conditions for vaporization by using different CsI + CsOH mixture contents showed that the ionization of the Cs 2 IOH(g) molecule led to five different fragment ions, Cs 2 OH + , Cs 2 I + , Cs + , CsOH + and CsI + . This complex ionization pattern was studied in relation with previous assessed values for the vaporization of CsOH and CsI pure compounds in which monomer and dimer molecules are predominant. The equilibrium constant for the reaction CsI(g) + CsOH(g) = Cs 2 IOH(g) was determined and, after modeling the structure of the Cs 2 IOH molecule, the enthalpy of formation was determined using the third law of thermodynamics, as follows: Δ f H°(Cs 2 IOH, g, 298.15 K) = −578 ± 14.7 kJ · mole −1

  15. The use of kragten spreadsheets for uncertainty evaluation of uranium potentiometric analysis by the Brazilian Safeguards Laboratory

    International Nuclear Information System (INIS)

    Silva, Jose Wanderley S. da; Barros, Pedro Dionisio de; Araujo, Radier Mario S. de

    2009-01-01

    In safeguards, independent analysis of uranium content and enrichment of nuclear materials to verify operator's declarations is an important tool to evaluate the accountability system applied by nuclear installations. This determination may be performed by nondestructive (NDA) methods, generally done in the field using portable radiation detection systems, or destructive (DA) methods by chemical analysis when more accurate and precise results are necessary. Samples for DA analysis are collected by inspectors during safeguards inspections and sent to Safeguards Laboratory (LASAL) of the Brazilian Nuclear Energy Commission - (CNEN), where the analysis take place. The method used by LASAL for determination of uranium in different physical and chemical forms is the Davies and Gray/NBL using an automatic potentiometric titrator, which performs the titration of uranium IV by a standard solution of K 2 Cr 2 O 7 . Uncertainty budgets have been determined based on the concepts of the ISO 'Guide to the Expression of Uncertainty in Measurement' (GUM). In order to simplify the calculation of the uncertainty, a computational tool named Kragten Spreadsheet was used. Such spreadsheet uses the concepts established by the GUM and provides results that numerically approximates to those obtained by propagation of uncertainty with analytically determined sensitivity coefficients. The main parameters (input quantities) interfering on the uncertainty were studied. In order to evaluate their contribution in the final uncertainty, the uncertainties of all steps of the analytical method were estimated and compiled. (author)

  16. Programa de ajuste multiparamétrico de curvas de titulação potenciométricas de ácidos húmicos Multiparametric adjustment program of potentiometric titration curves of humic acids

    Directory of Open Access Journals (Sweden)

    Clausius Duque Gonçalves Reis

    2010-04-01

    Full Text Available Tendo em vista a dificuldade de determinação dos pontos de inflexão na curva de titulação potenciométrica de ácidos húmicos, por metodologias tradicionais, foi desenvolvido foi desenvolvido um programa na linguagem Delphi para ajuste multiparamétrico de dados de titulação potenciométrica. Para isso um processo iterativo para estimar as raízes de um polinômio, com base no método de Newton-Raphson, foi utilizado. Os dados das titulações potenciométricas de ácidos húmicos usados nas regressões foram obtidos em um sistema automatizado de titulação potenciométrica. O programa desenvolvido na linguagem Delphi permite maior versatilidade e facilidade de operação, com uma interação mais amigável com o usuário. As curvas de titulação potenciométricas ajustadas sobrepuseram-se quase que totalmente às curvas experimentais. Os valores de pKa e as percentagens de grupos tituláveis dos ácidos húmicos, parâmetros ajustáveis na regressão multiparamétrica, apresentaram valores comparáveis com dados da literatura.Regarding the difficulty of determining the inflection points in the potentiometric titration curve of humic acids by means of traditional methodologies, a Delphi program a Delphi program was developed for the multiparametric data adjustment in potentiometric titration. For this purpose, an iterative process was used, based on the Newton-Raphson method to estimate the roots of a polynomial. The humic acid potentiometric titration data, used in regressions, were obtained in an automated system of potentiometric titration. The program developed in Delphi language features greater versatility, ease of operation and better interaction with the user. The adjusted potentiometric titration curves overlap the experimental curves almost entirely. The pKa values and percentages of titrable groups of humic acids extracted from soil, adjustable parameters in the multiparametric regression, were comparable with those reported

  17. The theoretical study of full spectrum analysis method for airborne gamma-ray spectrometric data

    International Nuclear Information System (INIS)

    Ni Weichong

    2011-01-01

    Spectra of airborne gamma-ray spectrometry was found to be the synthesis of spectral components of radioelement sources by analyzing the constitution of radioactive sources for airborne gamma-ray spectrometric survey and establishing the models of gamma-ray measurement. The mathematical equation for analysising airborne gamma-ray full spectrometric data can be expressed into matrix and related expansions were developed for the mineral resources exploration, environmental radiation measurement, nuclear emergency monitoring, and so on. Theoretical study showed that the atmospheric radon could be directly computed by airborne gamma-ray spectrometric data with full spectrum analysis without the use of the accessional upward-looking detectors. (authors)

  18. Potentiometric investigation of acid dissociation and anionic homoconjugation equilibria of substituted phenols in dimethyl sulfoxide[Substituted phenols; Acid-base equilibria; Dimethyl sulfoxide (DMSO); Potentiometry

    Energy Technology Data Exchange (ETDEWEB)

    Czaja, Malgorzata; Kozak, Anna; Makowski, Mariusz; Chmurzynski, Lech. E-mail: lech@chemik.chem.univ.gda.pl

    2003-10-01

    Standard acidity constants, K{sub a}{sup DMSO} (HA), expressed as pK{sub a}{sup DMSO} (HA) values, and anionic homoconjugation constants, K{sup DMSO}{sub AHA{sup -}}, (in the form of lg K{sup DMSO}{sub AHA{sup -}} values) have been determined for 11 substituted phenol-phenolate systems a polar protophilic aprotic solvent, dimethyl sulfoxide (DMSO) with a potentiometric titration. A linear relationship has been determined between lg K{sup DMSO}{sub AHA{sup -}} and pK{sub a}{sup DMSO} (HA). The tendency towards anionic homoconjugation in these systems increases with increasing pK{sub a}{sup DMSO} (HA) that is with declining phenol acidity. The pK{sub a}{sup DMSO} (HA) are correlated with both pK{sub a}{sup W} (HA) water and other polar non-aqeous solvents.

  19. Mass spectrometric study of vaporization of cesium tellurate and tellurite

    International Nuclear Information System (INIS)

    Semenov, G.A.; Fokina, L.A.; Mouldagalieva, R.A.

    1994-01-01

    The process of vaporization of cesium tellurate and tellurite was studied by the Knudsen effusion method with a mass spectrometric analysis of the vapor composition. The thermal dissociation of Cs 2 TeO 4 to Cs 2 TeO 3 and the congruent vaporization of Cs 2 TeO 3 were established. Thermodynamic functions for gaseous Cs 2 TeO 3 have been calculated. The standard enthalpy of sublimation Δ s H (298.15)=268.1±13.0 kJ mol -1 was determined by the 2nd and 3rd laws of thermodynamics. The enthalpy of formation Δ f H (298.15)=-725.1±13.0 kJ mol -1 for gaseous Cs 2 TeO 3 and the enthalpy of atomization Δ at H (298.15)=1841.3±15.0 kJ mol -1 have been computed. ((orig.))

  20. Mass spectrometric methods for trace analysis of metals

    International Nuclear Information System (INIS)

    Bahr, U.; Schulten, H.R.

    1981-01-01

    A brief outline is given of the principles of mass spectrometry (MS) and the fundamentals of qualitative and quantitative mass spectrometric analysis emphasizing recent developments and results. Classical methods of the analysis of solids, i.e. spark-source MS and thermal ionization MS, as well as recent methods of metal analysis are described. Focal points in this survey of recently developed techniques include secondary ion MS, laser probe MS, plasma ion source MS, gas discharge MS and field desorption MS. Here, a more detailed description is given and the merits of these emerging methods are discussed more explicitly. In particular, the results of the field desorption techniques in elemental analyses are reviewed and critically evaluated

  1. 5th colloquium on atomic spectrometric trace analysis

    International Nuclear Information System (INIS)

    Welz, B.

    1989-01-01

    This book deals with apparatus, use-oriented and theoretical aspects of trace analysis and spectroscopy. General articles are concerned with the analysis of environmentally relevant samples; a comparison of modern spectroscopic techniques, the coupling of hydride production, chromatography and spectrometry; chemical modifiers for graphite tube furnace atomic absorption spectroscopy (AAS), and possible applications of flow injection to atomic spectrometric trace analysis - one of the outstanding subjects of the colloquium. About one quarter of the 85 contributions deals with new techniques including flow injection. Other priority subjects are the theory and application of graphite tube furnace AAS, and a comparison between different dissolution methods and direct solid analysis. Medicine and toxicology, analysis of biological materials and environmentally relevant samples are in the foreground of use-oriented papers. (orig./BBR) [de

  2. Modern spectrometric methods for the analysis of labelled compounds

    International Nuclear Information System (INIS)

    Kaspersen, F.M.; Funke, C.W.; Wagenaars, G.N.; Jacobs, P.L.

    1988-01-01

    A proper analysis of chemical compounds should give information about the chemical identity (not only the structure but also enantiomeric form), the chemical purity and chemical composition (e.g. giving information about counter-ions, solvents of crystallization). For labelled compounds information is also needed about isotopic purity (defined as the % of isotope present in the compound), the position/distribution of the isotope in the molecule and degree of labelling/specific activity. In the past ten years the possibilities for spectrometric analyses of labelled compounds have increased enormously and this chapter will give an overview of these methods with the exception of (radio)chromatography that will be dealt with in another chapter. (author)

  3. Self-assembly of SiO2 nanoparticles for the potentiometric detection of neurotransmitter acetylcholine and its inhibitor.

    Science.gov (United States)

    Arruda, Izabela G; Guimarães, Francisco E G; Ramos, Romildo J; Vieira, Nirton C S

    2014-09-01

    The detection and quantification of neurotransmitter acetylcholine (ACh) are relevant because modifications in the ACh levels constitute a threat to human health. The biological regulator of this neurotransmitter is acetylcholinesterase (AChE), an enzyme that catalyzes the hydrolysis of ACh to choline and acetic acid. However, its activity is inhibited in the presence of organophosphate and carbamate pesticides, compromising the degradation of the neurotransmitter. There has been a growing interest in faster and more sensitive detection systems that include new methods and materials for the determination of the ACh concentration. This paper proposes a potentiometric biosensor for the detection of neurotransmitter ACh and its inhibitors, specifically organophosphate pesticide methamidophos. The biosensor is based on a self-assembled platform formed by poly(allylamine) hydrochloride (PAH) and silicon dioxide nanoparticles (SiO2-Np) that contains the immobilized enzyme AChE. First, the responses of the biosensor were investigated for different concentrations of ACh in buffer solutions. After quantifying ACh, the inhibition of AChE in the presence of methamidophos was determined, enabling the quantification of methamidophos expressed as the percentage of enzyme inhibition. The potential advantages of this biosensor include simplicity in building the electrode, possible production on an industrial scale, limited need for qualified personnel to operate the device and low processing cost.

  4. Fusion of Potentiometric & Voltammetric Electronic Tongue for Classification of Black Tea Taste based on Theaflavins (TF) Content

    Science.gov (United States)

    Bhattacharyya, Nabarun; Legin, Andrey; Papieva, Irina; Sarkar, Subrata; Kirsanov, Dmitry; Kartsova, Anna; Ghosh, Arunangshu; Bandyopadhyay, Rajib

    2011-09-01

    Black tea is an extensively consumed beverage worldwide with an expanding market. The final quality of black tea depends upon number of chemical compounds present in the tea. Out of these compounds, theaflavins (TF), which is responsible for astringency in black tea, plays an important role in determining the final taste of the finished black tea. The present paper reports our effort to correlate the theaflavins contents with the voltammetric and potentiometric electronic tongue (e-tongue) data. Noble metal-based electrode array has been used for collecting data though voltammetric electronic tongue where as liquid filled membrane based electrodes have been used for potentiometric electronic tongue. Black tea samples with tea taster score and biochemical results have been collected from Tea Research Association, Tocklai, India for the analysis purpose. In this paper, voltammetric and potentiometric e-tongue responses are combined to demonstrate improvement of cluster formation among tea samples with different ranges of TF values.

  5. New potentiometric and spectrophotometric methods for the determination of dextromethorphan in pharmaceutical preparations.

    Science.gov (United States)

    Elmosallamy, Mohamed A F; Amin, Alaa S

    2014-01-01

    New, simple and convenient potentiometric and spectrophotometric methods are described for the determination of dextromethorphan hydrobromide (DXM) in pharmaceutical preparations. The potentiometric technique is based on developing a potentiometric sensor incorporating the dextromethorphan tetrakis(p-chlorophenyl)borate ion-pair complex as an electroactive species in a plasticized PVC matrix membrane with o-nitophenyl octyl ether or dioctyl phthalate. The sensor shows a rapid near Nernstian response of over 1 × 10(-5) - 1 × 10(-2) mol L(-1) dextromethorphan in the pH range of 3.0 - 9.0. The detection limit is 2 × 10(-6) mol L(-1) DXM and the response time is instantaneous (2 s). The proposed spectrophotometric technique involves the reaction of DXM with eriochrom black T (EBT) to form an ion-associate complex. Solvent extraction is used to improve the selectivity of the method. The optimal extraction and reaction conditions have been studied, and the analytical characteristics of the method have been obtained. Linearity is obeyed in the range of 7.37 - 73.7 × 10(-5) mol L(-1) DXM, and the detection limit of the method is 1.29 × 10(-5) mol L(-1). The relative standard deviation (RSD) and relative error for six replicate measurements of 3.685 × 10(-4) mol L(-1) are 0.672 and 0.855%, respectively. The interference effect of some excepients has also been tested. The drug contents in pharmaceutical preparations were successfully determined by the proposed methods by applying the standard-addition technique.

  6. Use of ion selective electrodes for potentiometric analysis of solutions containing cadmium and cyanide ions

    International Nuclear Information System (INIS)

    Aleksandrov, V.V.; Glazkova, E.N.; Izmajlova, G.A.

    1988-01-01

    Technique for cadmium potentiometric determination in the cadmium-plating cyanide electrolyte, which countains Cd(CN) n 2-n (n=1,2,3,4) complexes, is developed. Reactions of cadmium precipitation in the form of diethyldithiocarbamate serve as the ground for determination technique. Polycrystalline membrane electrodes with hard contact are used as indicator electrodes. Pd, Ni, Cu, Ag do not interfere with cadmium determination, Fe, Zn, Bi may coprecipitate with cadmium. Determination limit of cadmium ions is 5x10 -3 M

  7. Structural characterization of hexadecyltrimethylammonium-smectite composites and their potentiometric electrode applications

    Energy Technology Data Exchange (ETDEWEB)

    Cubuk, Osman [Department of Chemistry, Faculty of Arts and Sciences, Erzincan University, 24100 Erzincan (Turkey); Caglar, Bulent, E-mail: bcaglar55@gmail.com [Department of Chemistry, Faculty of Arts and Sciences, Erzincan University, 24100 Erzincan (Turkey); Topcu, Cihan; Coldur, Fatih; Sarp, Gokhan [Department of Chemistry, Faculty of Arts and Sciences, Erzincan University, 24100 Erzincan (Turkey); Tabak, Ahmet [Department of Chemistry, Faculty of Arts and Sciences, Recep Tayyip Erdoğan University, 53100 Rize (Turkey); Sahin, Erdal [Department of Chemistry, Faculty of Arts and Sciences, Erzincan University, 24100 Erzincan (Turkey)

    2015-05-30

    Graphical abstract: - Highlights: • Surfactant cations intercalated with different molecular arrangements into smectite layers. • The electrophoretic mobility values indicate that excess surfactant loadings also create positive charges on the organosmectites surfaces. • A novel potentiometric SCN{sup −} selective electrode was fabricated based on modified smectite. - Abstract: Organosmectites were prepared by the intercalation of hexadecyltrimethylammonium cations at various ratios into interlayer of Unye smectite. Structural, thermal, morphological and textural properties of the synthesized organosmectites were characterized. Afterwards, a novel potentiometric PVC-membrane thiocyanate selective electrode was prepared based on the obtained hexadecyltrimethylammonium modified smectites as electroactive material. The basal spacing values of organosmectites were observed in the range of 15.61 and 35.50 Å. Powder X-ray diffraction data show that the surfactant cations penetrated into the smectite layers with different molecular arrangements. Modification of smectite with hexadecyltrimethylammonium led to appreciable decreases in the intensities of the FTIR bands at 3402 and 1635 cm{sup −1} and the new characteristic vibrational bands at 2927, 2850, 1472 and 722 cm{sup −1} originating from the surfactant molecules appeared. The thermal analysis data showed that the decomposition of surfactant species occurred in the temperature range of 170–720 °C and the amount of dehydrated water gradually decreased with the increase in surfactant amount. The intercalation of surfactant species within the gallery spacing led gradually to smaller surface areas. In addition, the electrophoretic mobility values indicate that excess surfactant loadings also generate positive charges on the organosmectite surfaces. The most convenient membrane composition resulting in the best potentiometric performance was investigated. The optimum membrane composition was determined to

  8. Data processing for potentiometric precipitation titration of mixtures of isovalent ions by linear regression analysis

    International Nuclear Information System (INIS)

    Mar'yanov, B.M.; Shumar, S.V.; Gavrilenko, M.A.

    1994-01-01

    A method for the computer processing of the curves of potentiometric differential titration using the precipitation reactions is developed. This method is based on transformation of the titration curve into a line of multiphase regression, whose parameters determine the equivalence points and the solubility products of the formed precipitates. The computational algorithm is tested using experimental curves for the titration of solutions containing Hg(2) and Cd(2) by the solution of sodium diethyldithiocarbamate. The random errors (RSD) for the titration of 1x10 -4 M solutions are in the range of 3-6%. 7 refs.; 2 figs.; 1 tab

  9. Analysis of Lead and Zinc by Mercury-Free Potentiometric Stripping Analysis

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov

    1997-01-01

    A method is presented for trace-element analysis of lead and zinc by potentiometric stripping analysis (PSA) where both the glassy-carbon working electrode and the electrolyte are free of mercury. Analysis of zinc requires an activation procedure of the glassy-carbon electrode. The activation...... is performed by pre-concentrating zinc on glassy carbon at -1400 mV(SCE) in a mercury-free electrolyte containing 0.1 M HCl and 2 ppm Zn2+, followed by stripping at approx. -1050 mV. A linear relationship between stripping peak areas, recorded in the derivative mode, and concentration was found...

  10. Stability constants of some Y(III)-complexes from potentiometric data

    Energy Technology Data Exchange (ETDEWEB)

    Pande, S P; Munshi, K N [Nagpur Univ. (India). Dept. of Chemistry

    1975-06-01

    Potentiometric studies have been carried out on the metal complexes of yttrium(III) with 5-sulphosalicylic acid 3,5-dinitro salicylic acid sodium 2,3-dihydroxynaphthalene-6-sulfonate, and nitroso-R-salt. The Calvin-Bjerrum pH-titration technique, as used by Iriving and Rossotti, has been applied to determine the stepwise protonation constants of the ligands and the formation constants of the complexes. The log K values have been computed by alternative methods, at three different temperatures at an ionic strength of 0.2M(NaClO/sub 4/).(author).

  11. Indirect potentiometric titration of ascorbic acid in pharmaceutical preparations using copper based mercury film electrode.

    Science.gov (United States)

    Abdul Kamal Nazer, Meeran Mohideen; Hameed, Abdul Rahman Shahul; Riyazuddin, Patel

    2004-01-01

    A simple and rapid potentiometric method for the estimation of ascorbic acid in pharmaceutical dosage forms has been developed. The method is based on treating ascorbic acid with iodine and titration of the iodide produced equivalent to ascorbic acid with silver nitrate using Copper Based Mercury Film Electrode (CBMFE) as an indicator electrode. Interference study was carried to check possible interference of usual excipients and other vitamins. The precision and accuracy of the method was assessed by the application of lack-of-fit test and other statistical methods. The results of the proposed method and British Pharmacopoeia method were compared using F and t-statistical tests of significance.

  12. Accurate and precise determination of small quantity uranium by means of automatic potentiometric titration

    International Nuclear Information System (INIS)

    Liu Quanwei; Luo Zhongyan; Zhu Haiqiao; Wu Jizong

    2007-01-01

    For high radioactivity level of dissolved solution of spent fuel and the solution of uranium product, radioactive hazard must be considered and reduced as low as possible during accurate determination of uranium. In this work automatic potentiometric titration was applied and the sample only 10 mg of uranium contained was taken in order to reduce the harm of analyzer suffered from the radioactivity. RSD<0.06%, at the same time the result can be corrected for more reliable and accurate measurement. The determination method can effectively reduce the harm of analyzer suffered from the radioactivity, and meets the requirement of reliable accurate measurement of uranium. (authors)

  13. Determination of uranyl ion by potentiometric titration using an uranyl-selective electrode

    International Nuclear Information System (INIS)

    Nassory, N.S.

    1990-01-01

    A potentiometric titration of uranyl ion is described using an uranyl selective electrode based on a membrane containing a complex of UO 2 -bis[di-4-(1,1,3,3-tetramethylbutyl)phenyl phosphate] as an ion-exchanger and tritolyl phosphate as a solvent mediator. The titrations were carried out with various titrants: Sodium hydroxide, potassium fluoride and sodium salts of acetate, oxalate and citrate. The equivalence points were determined by Gran's method. Good results were obtained by using sodium oxalate as a titrant for the determination of uranium in several samples of ammonium diuranate. The results were quite comparable with those obtained by X-ray fluorescence spectrometry. (orig.)

  14. Determination of sulfur compounds in hydrotreated transformer base oil by potentiometric titration.

    Science.gov (United States)

    Chao, Qiu; Sheng, Han; Cheng, Xingguo; Ren, Tianhui

    2005-06-01

    A method was developed to analyze the distribution of sulfur compounds in model sulfur compounds by potentiometric titration, and applied to analyze hydrotreated transformer base oil. Model thioethers were oxidized to corresponding sulfoxides by tetrabutylammonium periodate and sodium metaperiodate, respectively, and the sulfoxides were titrated by perchloric acid titrant in acetic anhydride. The contents of aliphatic thioethers and total thioethers were then determined from that of sulfoxides in solution. The method was applied to determine the organic sulfur compounds in hydrotreated transformer base oil.

  15. Determination of plutonium and uranium in the same aliquot by potentiometric titration

    International Nuclear Information System (INIS)

    Karekar, C.V.; Chander, Keshav; Nair, G.M.; Natarajan, P.R.

    1986-01-01

    A potentiometric titration method was developed for the determination of plutonium and uranium in the same aliquot in nitric acid medium. Plutonium was first determined by oxidation to Pu(VI) by fuming with HClO 4 . Pu(VI) was reduced to Pu(IV) with known excess of Fe(II). Uranium in the same solution was determined by reduction to U(IV) with Fe(II) in H 3 PO 4 medium. For the quantity of plutonium and uranium in the range of 3-5 mg per aliquot a precision of +-0.2% and +-0.4%, respectively, was obtained. (author)

  16. Potentiometric and spectrophotometric titration study of interaction of tungstovanadophosphoric heteropolyacids with sodium hydroxide

    International Nuclear Information System (INIS)

    Borkoyakov, S.A.; Fisun, L.A.

    1988-01-01

    The methods of potentiometric and spectrophotometric titration are used to study H s+n PW 12-n V n O 40 (n=1,2) (P-W-V HPA) decomposition by sodium hydroxide. It is shown that at the first stage of heteropolyanion interaction with alkali (pH) > 4 P-W-V HPA structural reconstruction takes place. It is accompanied by the formation of complexes with a higher content of vanadium atoms stable at pH 4-7/ P-W-V HPA decomposition to initial salts occurs at pH > 8

  17. Method for linearizing the potentiometric curves of precipitation titration in nonaqueous and aqueous-organic solutions

    International Nuclear Information System (INIS)

    Bykova, L.N.; Chesnokova, O.Ya.; Orlova, M.V.

    1995-01-01

    The method for linearizing the potentiometric curves of precipitation titration is studied for its application in the determination of halide ions (Cl - , Br - , I - ) in dimethylacetamide, dimethylformamide, in which titration is complicated by additional equilibrium processes. It is found that the method of linearization permits the determination of the titrant volume at the end point of titration to high accuracy in the case of titration curves without a potential jump in the proximity of the equivalent point (5 x 10 -5 M). 3 refs., 2 figs., 3 tabs

  18. Integrated potentiometric detector for use in chip-based flow cells

    Science.gov (United States)

    Tantra; Manz

    2000-07-01

    A new kind of potentiometric chip sensor for ion-selective electrodes (ISE) based on a solvent polymeric membrane is described. The chip sensor is designed to trap the organic cocktail inside the chip and to permit sample solution to flow past the membrane. The design allows the sensor to overcome technical problems of ruggedness and would therefore be ideal for industrial processes. The sensor performance for a Ba2+-ISE membrane based on a Vogtle ionophore showed electrochemical behavior similar to that observed in conventional electrodes and microelectrode arrangements.

  19. Interlaboratory comparison exercise for the determination of uranium by potentiometric titration (first phase)

    International Nuclear Information System (INIS)

    Verdingh, V.; Le Duigou, Y.

    1991-01-01

    Upon request of the Esarda working group on low-enriched uranium conversion and fuel fabrication plants an interlaboratory comparison was organized, to assess the precision and accuracy concerning the determination of uranium by the potentiometric titration method. This report presents the results of the first phase of this exercise (pure uranyl-nitrate solutions). The solutions used in this intercomparison have been certified for their uranium content by the CBNM, Geel. Comparison of the laboratory results with the certified values shows excellent, good and fairly good agreement for many of the participating laboratories. 10 tabs., 5 figs., 10 refs

  20. Method of semi-automatic high precision potentiometric titration for characterization of uranium compounds

    International Nuclear Information System (INIS)

    Cristiano, Barbara Fernandes G.; Dias, Fabio C.; Barros, Pedro D. de; Araujo, Radier Mario S. de; Delgado, Jose Ubiratan; Silva, Jose Wanderley S. da; Lopes, Ricardo T.

    2011-01-01

    The method of high precision potentiometric titration is widely used in the certification and characterization of uranium compounds. In order to reduce the analysis and diminish the influence if the annalist, a semi-automatic version of the method was developed at the safeguards laboratory of the CNEN-RJ, Brazil. The method was applied with traceability guaranteed by use of primary standard of potassium dichromate. The standard uncertainty combined in the determination of concentration of total uranium was of the order of 0.01%, which is better related to traditionally methods used by the nuclear installations which is of the order of 0.1%

  1. Use of 3-(4-hydroxyphenyl)propionic acid as electron donating compound in a potentiometric aflatoxin M{sub 1}-immunosensor

    Energy Technology Data Exchange (ETDEWEB)

    Rameil, Steffen, E-mail: s.rameil@r-biopharm.de [R-Biopharm AG, An der neuen Bergstrasse 17, 64297 Darmstadt (Germany); Schubert, Peter, E-mail: p.schubert@r-biopharm.de [R-Biopharm AG, An der neuen Bergstrasse 17, 64297 Darmstadt (Germany); Grundmann, Peter, E-mail: peter.grundmann@jennewein-biotech.de [R-Biopharm AG, An der neuen Bergstrasse 17, 64297 Darmstadt (Germany); Dietrich, Richard, E-mail: R.Dietrich@mh.vetmed.uni-muenchen.de [Department of Veterinary Sciences, University of Munich, Schoenleutner Str 8, 85764 Oberschleissheim (Germany); Maertlbauer, Erwin, E-mail: E.Maertlbauer@mh.vetmed.uni-muenchen.de [Department of Veterinary Sciences, University of Munich, Schoenleutner Str 8, 85764 Oberschleissheim (Germany)

    2010-02-19

    We developed a potentiometric aflatoxin M{sub 1}-immunosensor which utilizes 3-(4-hydroxyphenyl)propionic acid (p-HPPA) as electron donating compound for horseradish peroxidase (HRP; EC 1.11.1.7). The assay system consists of a polypyrrole-surface-working electrode coated with a polyclonal anti-M{sub 1} antibody (pAb-AFM{sub 1}), a Ag/AgCl reference electrode and a HRP-aflatoxin B{sub 1} conjugate (HRP-AFB{sub 1} conjugate). To optimize the potentiometric measuring system p-HPPA as well as related compounds serving as electron donating compounds were compared. Also the influence of different buffer systems, varying pH and substrate concentrations on signal intensity was investigated. Our results suggest that reaction conditions that favor the formation of Pummerer's type ketones lead to an increase in signal intensity rather than formation of fluorescent dye. Comparison with commercial ready-to-use HRP electron donating compounds such as 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), o-phenylenediamine (OPD) or 3,3',5,5'-tetramethylbenzidine (TMB) showed that only 34%, 77% and 49% of the signal intensity of p-HPPA were reached, respectively. The optimized assay had a detection limit of 40 pg mL{sup -1} and allowed detection of 500 pg mL{sup -1} (FDA action limit) aflatoxin M{sub 1} (AFM{sub 1}) in pasteurized milk and UHT-milk containing 0.3-3.8% fat within 10 min without any sample treatment. The working range was between 250 and 2000 pg mL{sup -1} AFM{sub 1}.

  2. Mass spectrometric identification of isoforms of PR proteins in xylem sap of fungus-infected tomato

    NARCIS (Netherlands)

    Rep, Martijn; Dekker, Henk L.; Vossen, Jack H.; de Boer, Albert D.; Houterman, Petra M.; Speijer, Dave; Back, Jaap W.; de Koster, Chris G.; Cornelissen, Ben J. C.

    2002-01-01

    The protein content of tomato (Lycopersicon esculentum) xylem sap was found to change dramatically upon infection with the vascular wilt fungus Fusarium oxysporum. Peptide mass fingerprinting and mass spectrometric sequencing were used to identify the most abundant proteins appearing during

  3. The Difference Between the Potentiometric Surfaces of the Upper Patapsco Aquifer in Southern Maryland, September 1990 and September 2007

    Science.gov (United States)

    Curtin, Stephen E.; Andreasen, David C.; Staley, Andrew W.

    2009-01-01

    This report presents a map showing the change in the potentiometric surface of the upper Patapsco aquifer in the Patapsco Formation of Early Cretaceous age in Southern Maryland for September 1990 and September 2007. The map, based on water-level measurements in 33 wells, shows that during the 17-year period, the change in the potentiometric surface ranged from zero at the edge of the outcrop area in northern Anne Arundel County to a decline of 28 feet at Crofton Meadows, 38 feet at Arnold, 36 feet at Waldorf, 35 feet at the Chalk Point power plant, and 40 feet at Lexington Park.

  4. The Difference Between the Potentiometric Surfaces of the Magothy Aquifer in Southern Maryland, September 1975 and September 2007

    Science.gov (United States)

    Curtin, Stephen E.; Andreasen, David C.; Staley, Andrew W.

    2009-01-01

    This report presents a map showing the change in the potentiometric surface of the Magothy aquifer in the Magothy Formation of Late Cretaceous age in Southern Maryland for September 1975 and September 2007. The map, based on water-level measurements in 51 wells, shows that during the 32-year period, the potentiometric surface had no change at the outcrop area, which is in the northernmost part of the study area, but declined 90 feet at Waldorf. Waldorf is located near the southwesternmost part of the study area, and approaches the downdip boundary of the aquifer.

  5. The Difference Between the Potentiometric Surfaces of the Magothy Aquifer in Southern Maryland, September 1975 and September 2009

    Science.gov (United States)

    Curtin, Stephen E.; Andreasen, David C.; Staley, Andrew W.

    2010-01-01

    This report presents a map showing the change in the potentiometric surface of the Magothy aquifer in the Magothy Formation of Late Cretaceous age in Southern Maryland between September 1975 and September 2009. The map, based on water level differences obtained from 48 wells, shows that during the 34-year period, the potentiometric surface had little change at the outcrop area, which is in the northernmost part of the study area, but declined 75 feet at Waldorf. Waldorf is located near the southwesternmost part of the study area, and approaches the downdip boundary of the aquifer. The map also shows well yield in gallons per day for 2008 at wells or well fields.

  6. Potentiometric study of rare earth complexing with trans-1,2-diaminocyclohexane-N,N'-dimalonic acid

    International Nuclear Information System (INIS)

    Smirnova, T.I.; Gorelov, I.P.

    1980-01-01

    Complexing of rare earths (Ln) and yttrium with trans-1,2-diaminocyclohexane-N, N'-dimalonic acid in aqueous solutions is studied using indirect potentiometric method with an aid of stationary mercury electrode and by the method of pH-potentiometric titration. It is shown that in the investigated solutions the LnL - and LnL 2 5- complexes are formed. At 25 deg C and ion force 0.1 stability constants of the complexes detected are determined [ru

  7. Direct evidence of ionic fluxes across ion-selective membranes: a scanning electrochemical microscopic and potentiometric study.

    Science.gov (United States)

    Gyurcsányi, R E; Pergel, E; Nagy, R; Kapui, I; Lan, B T; Tóth, K; Bitter, I; Lindner, E

    2001-05-01

    Scanning electrochemical microscopy (SECM) supplemented with potentiometric measurements was used to follow the time-dependent buildup of a steady-state diffusion layer at the aqueous-phase boundary of lead ion-selective electrodes (ISEs). Differential pulse voltammetry is adapted to SECM for probing the local concentration profiles at the sample side of solvent polymeric membranes. Major factors affecting the membrane transport-related surface concentrations were identified from SECM data and the potentiometric transients obtained under different experimental conditions (inner filling solution composition, membrane thickness, surface pretreatment). The amperometrically determined surface concentrations correlated well with the lower detection limits of the lead ion-selective electrodes.

  8. Review of procedures involving separation and preconcentration for the determination of cadmium using spectrometric techniques

    International Nuclear Information System (INIS)

    Ferreira, Sergio L.C.; Andrade, Jailson B. de; Korn, Maria das Gracas A.; Pereira, Madson de G.; Lemos, Valfredo A.; Santos, Walter N.L. dos; Rodrigues, Frederico de Medeiros; Souza, Anderson S.; Ferreira, Hadla S.; Silva, Erik G.P. da

    2007-01-01

    Spectrometric techniques for the analysis of trace cadmium have developed rapidly due to the increasing need for accurate measurements at extremely low levels of this element in diverse matrices. This review covers separation and preconcentration procedures, such as electrochemical deposition, precipitation, coprecipitation, solid phase extraction, liquid-liquid extraction (LLE) and cloud point extraction (CPE), and consider the features of the their application with several spectrometric techniques

  9. Potentiometric urea biosensor based on an immobilised fullerene-urease bio-conjugate.

    Science.gov (United States)

    Saeedfar, Kasra; Heng, Lee Yook; Ling, Tan Ling; Rezayi, Majid

    2013-12-06

    A novel method for the rapid modification of fullerene for subsequent enzyme attachment to create a potentiometric biosensor is presented. Urease was immobilized onto the modified fullerene nanomaterial. The modified fullerene-immobilized urease (C60-urease) bioconjugate has been confirmed to catalyze the hydrolysis of urea in solution. The biomaterial was then deposited on a screen-printed electrode containing a non-plasticized poly(n-butyl acrylate) (PnBA) membrane entrapped with a hydrogen ionophore. This pH-selective membrane is intended to function as a potentiometric urea biosensor with the deposition of C60-urease on the PnBA membrane. Various parameters for fullerene modification and urease immobilization were investigated. The optimal pH and concentration of the phosphate buffer for the urea biosensor were 7.0 and 0.5 mM, respectively. The linear response range of the biosensor was from 2.31 × 10-3 M to 8.28 × 10-5 M. The biosensor's sensitivity was 59.67 ± 0.91 mV/decade, which is close to the theoretical value. Common cations such as Na+, K+, Ca2+, Mg2+ and NH4+ showed no obvious interference with the urea biosensor's response. The use of a fullerene-urease bio-conjugate and an acrylic membrane with good adhesion prevented the leaching of urease enzyme and thus increased the stability of the urea biosensor for up to 140 days.

  10. Potentiometric Zinc Ion Sensor Based on Honeycomb-Like NiO Nanostructures

    Directory of Open Access Journals (Sweden)

    Magnus Willander

    2012-11-01

    Full Text Available In this study honeycomb-like NiO nanostructures were grown on nickel foam by a simple hydrothermal growth method. The NiO nanostructures were characterized by field emission electron microscopy (FESEM, high resolution transmission electron microscopy (HRTEM and X-ray diffraction (XRD techniques. The characterized NiO nanostructures were uniform, dense and polycrystalline in the crystal phase. In addition to this, the NiO nanostructures were used in the development of a zinc ion sensor electrode by functionalization with the highly selective zinc ion ionophore 12-crown-4. The developed zinc ion sensor electrode has shown a good linear potentiometric response for a wide range of zinc ion concentrations, ranging from 0.001 mM to 100 mM, with sensitivity of 36 mV/decade. The detection limit of the present zinc ion sensor was found to be 0.0005 mM and it also displays a fast response time of less than 10 s. The proposed zinc ion sensor electrode has also shown good reproducibility, repeatability, storage stability and selectivity. The zinc ion sensor based on the functionalized NiO nanostructures was also used as indicator electrode in potentiometric titrations and it has demonstrated an acceptable stoichiometric relationship for the determination of zinc ion in unknown samples. The NiO nanostructures-based zinc ion sensor has potential for analysing zinc ion in various industrial, clinical and other real samples.

  11. Potentiometric urea biosensor utilizing nanobiocomposite of chitosan-iron oxide magnetic nanoparticles

    International Nuclear Information System (INIS)

    Ali, A; Israr, M Q; Sadaf, J R; Nur, O; Willander, M; AlSalhi, M S; Atif, M; Ansari, Anees A; Ahmed, E

    2013-01-01

    The iron oxide (Fe 3 O 4 ) magnetic nanoparticles have been fabricated through a simple, cheap and reproducible approach. Scanning electron microscope, x-rays powder diffraction of the fabricated nanoparticles. Furthermore, the fabrication of potentiometric urea biosensor is carried out through drop casting the initially prepared isopropanol and chitosan solution, containing Fe 3 O 4 nanoparticles, on the glass fiber filter with a diameter of 2 cm and a copper wire (of thickness −500 μm) has been utilized to extract the voltage signal from the functionalized nanoparticles. The functionalization of surface of the Fe 3 O 4 nanoparticles is obtained by the electrostatically immobilization of urease onto the nanobiocomposite of the chitosan- Fe 3 O 4 in order to enhance the sensitivity, specificity, stability and reusability of urea biosensor. Electrochemical detection procedure has been adopted to measure the potentiometric response over the wide logarithmic concentration range of the 0.1 mM to 80 mM. The Fe 3 O 4 nanoparticles based urea biosensor depicts good sensitivity with ∼42 mV per decade at room temperature. Durability of the biosensor could be considerably enhanced by applying a thin layer of the nafion. In addition, the reasonably stable output response of the biosensor has been found to be around 12 sec.

  12. Potentiometric urea biosensor based on multi-walled carbon nanotubes (MWCNTs)/silica composite material

    International Nuclear Information System (INIS)

    Ahuja, Tarushee; Kumar, D.; Singh, Nahar; Biradar, A.M.; Rajesh

    2011-01-01

    A novel potentiometric urea biosensor has been fabricated with urease (Urs) immobilized multi-walled carbon nanotubes (MWCNTs) embedded in silica matrix deposited on the surface of indium tin oxide (ITO) coated glass plate. The enzyme Urs was covalently linked with the exposed free -COOH groups of functionalized MWCNTs (F-MWCNTs), which are subsequently incorporated within the silica matrix by sol-gel method. The Urs/MWCNTs/SiO 2 /ITO composite modified electrode was characterized by Fourier transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA) and UV-visible spectroscopy. The morphologies and electrochemical performance of the modified Urs/MWCNTs/SiO 2 /ITO electrode have been investigated by scanning electron microscopy (SEM) and potentiometric method, respectively. The synergistic effect of silica matrix, F-MWCNTs and biocompatibility of Urs/MWCNTs/SiO 2 made the biosensor to have the excellent electro catalytic activity and high stability. The resulting biosensor exhibits a good response performance to urea detection with a wide linear range from 2.18 x 10 -5 to 1.07 x 10 -3 M urea. The biosensor shows a short response time of 10-25 s and a high sensitivity of 23 mV/decade/cm 2 .

  13. Potentiometric Surface of the Lower Patapsco Aquifer in Southern Maryland, September 2007

    Science.gov (United States)

    Curtin, Stephen E.; Andreasen, David C.; Staley, Andrew W.

    2009-01-01

    This report presents a map showing the potentiometric surface of the lower Patapsco aquifer in the Patapsco Formation of Early Cretaceous age in Southern Maryland during September 2007. The map is based on water-level measurements in 65 wells. The highest measured water level was 111 feet above sea level near the northwestern boundary and outcrop area of the aquifer in northern Prince George's County. From this area, the potentiometric surface declined towards well fields at Severndale and Arnold. The measured ground-water levels were 87 feet below sea level at Severndale, and 42 feet below sea level at Arnold. There was also a cone of depression covering a large area in Charles County that includes Waldorf, La Plata, Indian Head, and the Morgantown power plant. The ground-water levels measured were as low as 219 feet below sea level at Waldorf, 187 feet below sea level at La Plata, 106 feet below sea level at Indian Head, and 89 feet below sea level at the Morgantown power plant.

  14. Potentiometric Surface of the Lower Patapsco Aquifer in Southern Maryland, September 2009

    Science.gov (United States)

    Curtin, Stephen E.; Andreasin, David C.; Staley, Andrew W.

    2010-01-01

    This report presents a map showing the potentiometric surface of the lower Patapsco aquifer in the Patapsco Formation of Early Cretaceous age in Southern Maryland during September 2009. The map is based on water-level measurements in 64 wells. The highest measured water level was 110 feet above sea level near the northwestern boundary and outcrop area of the aquifer in northern Prince George's County. From this area, the potentiometric surface declined towards well fields at Severndale, Broad Creek, and Arnold. The measured groundwater levels were 99 feet below sea level at Severndale, 50 feet below sea level at Broad Creek, and 36 feet below sea level at Arnold. There was also a cone of depression in Charles County that includes Waldorf, La Plata, Indian Head, and the Morgantown power plant. The groundwater levels measured were as low as 215 feet below sea level at Waldorf, 149 feet below sea level at La Plata, 121 feet below sea level at Indian Head, and 96 feet below sea level at the Morgantown power plant. The map also shows well yield in gallons per day for 2008 at wells or well fields.

  15. Potentiometric surface of the Upper Patapsco aquifer in southern Maryland, September 2009

    Science.gov (United States)

    Curtin, Stephen E.; Andreasen, David C.; Staley, Andrew W.

    2010-01-01

    This report presents a map showing the potentiometric surface of the upper Patapsco aquifer in the Patapsco Formation of Early Cretaceous age in Southern Maryland during September 2009. The map is based on water-level measurements in 65 wells. The highest measured water level was 118 feet above sea level near the northern boundary and outcrop area of the aquifer in northern Anne Arundel County. From this area, the potentiometric surface declined to the south toward a well field in the Annapolis-Arnold area, and from all directions toward three additional cones of depression. These cones are located in the Waldorf-La Plata area, Chalk Point, and the Leonardtown-Lexington Park area. The lowest measured groundwater levels were 26 feet below sea level at Annapolis, 108 feet below sea level south of Waldorf, 60 feet below sea level at Chalk Point, and 83 feet below sea level at Leonardtown. The map also shows well yield in gallons per day for 2008 at wells or well fields.

  16. Potentiometric Surface of the Upper Patapsco Aquifer in Southern Maryland, September 2007

    Science.gov (United States)

    Curtin, Stephen E.; Andreasen, David C.; Staley, Andrew W.

    2009-01-01

    This report presents a map showing the potentiometric surface of the upper Patapsco aquifer in the Patapsco Formation of Early Cretaceous age in Southern Maryland during September 2007. The map is based on water-level measurements in 50 wells. The highest measured water level was 120 feet above sea level near the northern boundary and outcrop area of the aquifer in northern Anne Arundel County. From this area, the potentiometric surface declined to the south toward a well field in the Annapolis-Arnold area, and from all directions toward four cones of depression. These cones are located in the Waldorf-La Plata area, Chalk Point-Prince Frederick area, Swan Point subdivision in southern Charles County, and the Lexington Park-St. Inigoes area. The lowest measured ground-water level was 44 feet below sea level at Arnold, 106 feet below sea level south of Waldorf, 54 feet below sea level at Swan Point, 59 feet below sea level at Chalk Point, and 58 feet below sea level at Lexington Park.

  17. New potentiometric sensor based on molecularly imprinted nanoparticles for cocaine detection.

    Science.gov (United States)

    Smolinska-Kempisty, K; Ahmad, O Sheej; Guerreiro, A; Karim, K; Piletska, E; Piletsky, S

    2017-10-15

    Here we present a potentiometric sensor for cocaine detection based on molecularly imprinted polymer nanoparticles (nanoMIPs) produced by the solid-phase imprinting method. The composition of polymers with high affinity for cocaine was optimised using molecular modelling. Four compositions were selected and polymers prepared using two protocols: chemical polymerisation in water and UV-initiated polymerisation in organic solvent. All synthesised nanoparticles had very good affinity to cocaine with dissociation constants between 0.6nM and 5.3nM. Imprinted polymers produced in organic solvent using acrylamide as a functional monomer demonstrated the highest yield and affinity, and so were selected for further sensor development. For this, nanoparticles were incorporated within a PVC matrix which was then used to prepare an ion-selective membrane integrated with a potentiometric transducer. It was demonstrated that the sensor was able to quantify cocaine in blood serum samples in the range of concentrations between 1nM and 1mM. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Potentiometric chemical sensors from lignin-poly(propylene oxide) copolymers doped by carbon nanotubes.

    Science.gov (United States)

    Rudnitskaya, Alisa; Evtuguin, Dmitry V; Costa, Luis C; Graça, M Pedro F; Fernandes, António J S; Correia, M Rosario P; Gomes, M Teresa S R; Oliveira, J A B P

    2013-01-21

    Hardwood and softwood lignins obtained from industrial sulphite and kraft and laboratory oxygen-organosolv pulping processes were employed in co-polymerization with tolylene 2,4-diisocyanate terminated poly(propylene glycol). The obtained lignin-based polyurethanes were doped with 0.72 w/w% of multiwall carbon nanotubes (MWCNTs) with the aim of increasing their electrical conductivity to the levels suitable for sensor applications. Effects of the polymer doping with MWCNTs were assessed using electrical impedance (EIS) and UV-Resonance Raman (UV-RR) spectroscopy. Potentiometric sensors were prepared by drop casting of liquid polymer on the surface of carbon glass or platinum electrodes. Lignin-based sensors displayed a very low or no sensitivity to all alkali, alkali-earth and transition metal cations ions except Cr(VI) at pH 2. Response to Cr(VI) values of 39, 50 and 53 mV pX(-1) for the sensors based on kraft, organosolv and lignosulphonate lignins, respectively, were observed. Redox sensitivity values close to the theoretical values of 20 and 21 mV pX(-1) for organosolv and lignosulphonate based sensors respectively were detected in the Cr(III)/Cr(VI) solutions while a very low response was observed in the solutions containing Fe(CN)(6)(3-/4-). Conducting composite lignin-based polyurethanes doped with MWCNTs were suggested as being promising materials for Cr(VI)-sensitive potentiometric sensors.

  19. Potentiometric microdetermination of cadmium in organic compounds after oxygen flask combustion

    International Nuclear Information System (INIS)

    Campiglio, A.

    1986-01-01

    The sample is burnt in an oxygen flask and the combustion products are absorbed in 1Μ HNO 3 . After removal of interfering gases by boiling, the solution is transfered to the titration cell and neutralized with NaOH in the presence of methyl red; cd(II) is finally titrated potentiometrically in a buffered 50% ethanolic medium with 0.01Μ sodium diethyldithiocarbamate in 50% ethanol. A silver/sulphide ion-selective electrode and a double junction referenceelectrode containing a 10% KNO 3 solution in 26% ethanol in the outer compartment are used in combination with a Titroprocessor to detect the end point. The results obtained are very accurate and reproducible: the maximum error does not exceed 0.09%, the recovery of cadmium is in the range 99.67 to 99.95% and the rel. standard deviation is 0.05%. The potentiometric titration with diethyldithiocarbamate, which is useful to determine small Cd(II) amounts down to 30μg (2μg ml -1 ), as well as the oxygen flask combustion of organic cadmium compounds are discussed. (Author)

  20. Combinatorial screening of potentiometric Pb(II) sensors from polysulfoaminoanthraquinone solid ionophore.

    Science.gov (United States)

    Huang, Mei-Rong; Ding, Yong-Bo; Li, Xin-Gui

    2014-03-10

    A potentiometric Pb(II)-selective sensor was fabricated by a combinatorial screening of electrically conducting polysulfoaminoanthraquinone (PSA) nanoparticles as a solid ionophore, ion exchangers (oleic acid (OA) and NaTPB), plasticizers in a polyvinyl chloride (PVC) matrix, membrane thickness, inner filling ion species, and concentration. The membrane sensor with the composition of PSA/PVC/DOP (dioctyl phthalate)/OA (1.0:33:61:5.0) exhibited the best performance, including a slope of 29.3 mV decade(-1) in the concentration range 10(-6.3)-10(-1.6) M, detection limit of 1.6 × 10(-7) M, response time of 16 s, lifetime of five months, and good response reversibility. The proposed sensor has demonstrated good selectivity for Pb(II) over other monovalent, divalent and trivalent interfering ions, and could be used in a pH range of 3.62-5.22. The Pb(II) sensor has been successfully applied for the determination of Pb(II) concentration in real-world samples and also as an indicator electrode for potentiometric titration of lead ions.

  1. Potentiometric assessment of iron release during ferritin reduction by exogenous agents.

    Science.gov (United States)

    Vladimirova, Lilia S; Kochev, Valery K

    2010-09-01

    This work studied the possibilities for quantitative determination of iron mobilization in connection with ferritin reduction by ascorbic acid (vitamin C) and sodium dithionite in vitro. The iron storage protein was incubated with an excess of reductant in aerobic conditions in the absence of complexing agents in the medium. The release of Fe(2+) was let to go to completion, and the overall content of Fe(2+) in the solution was evaluated with the aid of potentiometric titration using Ce(4+) as an oxidizing titrant. Results suggest a moderate iron efflux under the influence of the chosen reducing agents. Although such a reduction of the protein mineral core by dihydroxyfumarate contributes greatly to the iron mobilization, ferritin behavior with vitamin C and dithionite seems to be different. Although redox properties of dihydroxyfumarate are determined by hydroxyl groups similar to those of ascorbic acid, the two compounds differ significantly in structure, and this could be the basis for an explanation of the specificities in their interaction with ferritin. As revealed by the study, potentiometric titration promises to be a reliable tool for evaluation of the amount of Fe(2+) present in the solution as a result of the reduction of the ferritin's mineral core. 2010 Elsevier Inc. All rights reserved.

  2. A gas/liquid chromatographic-mass spectrometric method for the rapid screening of 250 pesticides in aqueous matrices

    Energy Technology Data Exchange (ETDEWEB)

    Chandramouli, B.; Harvan, D.; Brittain, S.; Hass, R. [Eno River Labs, LLC. Durham, NC (United States)

    2004-09-15

    Pesticide residues in food present a potentially serious and significant cause for concern. Many pesticides have been associated with significant health effects to the nervous and endocrine systems and some have been deemed carcinogenic. There are many well-established techniques for pesticide analysis. However, commercial pesticide methods have traditionally only been available for specific pesticide families, such as chlorinated pesticides or herbicides, and at detection limits ranging from 0.05 ppb to 1 ppm in aqueous matrices. Techniques that can quickly screen for the presence/absence of pesticide residues in food matrices are critical in ensuring the safety of food and water. This paper outlines a combined Gas Chromatographic-High Resolution Mass Spectrometric (GC-HRMS) and Liquid Chromatographic Tandem Mass Spectrometric (LC-MS/MS) screening assay for 250 pesticides that was developed for use in water, and soda samples at screening levels ranging from 0.1-5 ppb. The pesticides selected have been identified by the European Union as being of concern and the target of possible legislation. The list encompasses a variety of pesticide classes and compound groupings.

  3. Anion binding in the C3v-symmetric cavity of a protonated tripodal amine receptor: potentiometric and single crystal X-ray studies.

    Science.gov (United States)

    Bose, Purnandhu; Ravikumar, I; Ghosh, Pradyut

    2011-11-07

    Tris(2-aminoethyl)amine (tren) based pentafluorophenyl-substituted tripodal L, tris[[(2,3,4,5,6-pentafluorobenzyl)amino]ethyl]amine receptor is synthesized in good yield and characterized by single crystal X-ray diffraction analysis. Detailed structural aspects of binding of different anionic guests toward L in its triprotonated form are examined thoroughly. Crystallographic results show binding of fluoride in the C(3v)-symmetric cavity of [H(3)L](3+) where spherical anion fluoride is in tricoordinated geometry via (N-H)(+)···F interaction in the complex [H(3)L(F)]·[F](2)·2H(2)O, (3). In the case of complexes [H(3)L(OTs)]·[OTs](2), (4) and [H(3)L(OTs)]·[NO(3)]·[OTs], (5), tetrahedral p-toluenesulphonate ion is engulfed in the cavity of [H(3)L](3+) via (N-H)(+)···O interactions. Interestingly, complex [(H(3)L)(2)(SiF(6))]·[BF(4)](4)·CH(3)OH·H(2)O, (6) shows encapsulation of octahedral hexafluorosilicate in the dimeric capsular assembly of two [H(3)L](3+) units, via a number of (N-H)(+)···F interactions. The kinetic parameters of L upon binding with different anions are evaluated using a potentiometric study in solution state. The potentiometric titration experiments in a polar protic methanol/water (1:1 v/v) binary solvent system show high affinity of the receptor toward more basic fluoride and acetate anions, with a lesser affinity for other inorganic anions (e.g., chloride, bromide, nitrate, sulfate, dihydrogenphosphate, and p-toluenesulphonate). © 2011 American Chemical Society

  4. An efficient ab initio DFT and PCM assessment of the potentiometric selectivity of a salophen type Schiff base.

    Science.gov (United States)

    Demir, Serkan; Yilmaz, Hakan; Dilimulati, Maowulidan; Andaç, Müberra

    2014-06-01

    As a neutral carrier component for the preparation of a potentiometric membrane sensor, the affinity and selectivity of the salophen type Schiff base ligand obtained by 1:2 condensation of 2.3-diaminopyridine with salicylaldehyde toward a series of common cations has been fully examined by DFT/B3LYP and integral equation formalism polarizable continum model (IEF-PCM or only given with PCM as default input in the computations) in combination with the experimental data. Both the potentiometric measurements and DFT calculations have exhibited that the ionophore shows appreciable selectivity for Cu(2+) ion over other cations. Four different approaches where the last three are the modified version of each other have been evaluated and compared with potentiometric data. Based upon the results of comparison among the approaches suggested to verify the selective behavior of ionophore toward Cu(2+), PCM implemented approach having a whole computational groundwork has given well-matched results with the observed data and with the method augmented with experimental hydration energies. The foremost interferences were detected by determining potentiometric selectivity coefficients for each metal ion relative to Cu(2+) and compared to the results obtained by the DFT calculations.

  5. Comparison between amperometric and true potentiometric end-point detection in the determination of water by the Karl Fischer method.

    Science.gov (United States)

    Cedergren, A

    1974-06-01

    A rapid and sensitive method using true potentiometric end-point detection has been developed and compared with the conventional amperometric method for Karl Fischer determination of water. The effect of the sulphur dioxide concentration on the shape of the titration curve is shown. By using kinetic data it was possible to calculate the course of titrations and make comparisons with those found experimentally. The results prove that the main reaction is the slow step, both in the amperometric and the potentiometric method. Results obtained in the standardization of the Karl Fischer reagent showed that the potentiometric method, including titration to a preselected potential, gave a standard deviation of 0.001(1) mg of water per ml, the amperometric method using extrapolation 0.002(4) mg of water per ml and the amperometric titration to a pre-selected diffusion current 0.004(7) mg of water per ml. Theories and results dealing with dilution effects are presented. The time of analysis was 1-1.5 min for the potentiometric and 4-5 min for the amperometric method using extrapolation.

  6. Accurate potentiometric determination of lipid membrane-water partition coefficients and apparent dissociation constants of ionizable drugs: electrostatic corrections.

    Science.gov (United States)

    Elsayed, Mustafa M A; Vierl, Ulrich; Cevc, Gregor

    2009-06-01

    Potentiometric lipid membrane-water partition coefficient studies neglect electrostatic interactions to date; this leads to incorrect results. We herein show how to account properly for such interactions in potentiometric data analysis. We conducted potentiometric titration experiments to determine lipid membrane-water partition coefficients of four illustrative drugs, bupivacaine, diclofenac, ketoprofen and terbinafine. We then analyzed the results conventionally and with an improved analytical approach that considers Coulombic electrostatic interactions. The new analytical approach delivers robust partition coefficient values. In contrast, the conventional data analysis yields apparent partition coefficients of the ionized drug forms that depend on experimental conditions (mainly the lipid-drug ratio and the bulk ionic strength). This is due to changing electrostatic effects originating either from bound drug and/or lipid charges. A membrane comprising 10 mol-% mono-charged molecules in a 150 mM (monovalent) electrolyte solution yields results that differ by a factor of 4 from uncharged membranes results. Allowance for the Coulombic electrostatic interactions is a prerequisite for accurate and reliable determination of lipid membrane-water partition coefficients of ionizable drugs from potentiometric titration data. The same conclusion applies to all analytical methods involving drug binding to a surface.

  7. Potentiometric stripping analysis of Cadmium and Lead in superficial waters

    International Nuclear Information System (INIS)

    Arias, Juan Miguel; Marciales Castiblanco, Clara

    2003-01-01

    This paper contains the implementation and validation of an analytical method for determining cadmium and lead in surface waters. This is a valuable tool for the description of actual conditions and qualitative and quantitative control of dangerous heavy metals discharge in water bodies. Test were run for selecting stripping potentiometry conditions that as indicated by results were: sample oxidant concentration 36.4 μg/L Hg 2+ stirring frequency 2400 rpm, electrolysis time 80 s., electrolysis potential -950 mV and pH of 2.0. Interference of Cu 2+ and Fe 2+ showed that copper concentrations larger than 150 μg/L and 500 μg/L negatively influence the analytical response for Cadmium and lead respectively; [Fe 3+ ] larger than 60 μg/L and 400 μg/L cause variations in cadmium and lead read content respectively. Linear concentration range for cadmium lies between 5 and 250 μg/L; for lead range goes from 10 to 250 μg/L. Precision expressed as repeatability for both system and method, exhibit good reproducibility with variation coefficients below 6%. Accuracy, assessed from recuperation, is strongly influenced by concentration level therefore standard addition is recommended for lead and cadmium quantification. Analysis performed on surface waters from Colombian Magdalena and Cauca rivers pointed lead and cadmium contents below detection limits

  8. Radio spectrometric survey of un-surveyed areas in Syria

    International Nuclear Information System (INIS)

    Aissa, M.; Al-Hent, R; Jubeli, Y.

    2002-11-01

    The values and distribution of the radioelements e U, e Th, % K and Ur units in the surface geological formations of the west and south sectors of Syrian region, were estimated using carbone gamma ray spectrometric survey. The radiometric maps were prepared, as well as, many geological profiles, cross sections studied in different locations and geochemical samples were analyzed by laboratory gamma ray spectrometry and by x-ray diffractometry, the results of the all sets were compared. In general, the survey shows, low radioelement concentrations in the area, especially on basic rocks (Jabal Al-arab, Hawran) south Syria, and on ultra basic rocks (ophiolitic complex) north-west Syria, but there are some separate anomalous spots were connected with phosphate rocks, detected on cretaceous and Palaeogene age. Some times we noticed high radioelement concentrations haloes associated with fractured zones were already arise from secondary uranium mineralization, as a result of solutions movement through fissures in carbonatic and/or chalk like limestone rocks. finally, the obtained concentrations, represent a background values which has no significant importance for uranium exploration point of view. (author)

  9. Study of natural diamond detector spectrometric properties under neutron irradiation

    CERN Document Server

    Alekseyev, A B; Kaschuck, Y; Krasilnikov, A; Portnov, D; Tugarinov, S

    2002-01-01

    Natural diamond detector (NDD) performance was studied up to a neutron fluence of 10 sup 1 sup 5 neutron/cm sup 2. The variations of the NDD spectrometric response to incident alpha-particles from sup 2 sup 4 sup 1 Am source after exposure to fast neutron fluences up to 3x10 sup 1 sup 6 n/cm sup 2 were examined. No significant variations up to the level of 10 sup 1 sup 4 n/cm sup 2 were observed. Degradation of charge collection efficiency at higher fluences is reported. No remarkable increase of the NDD leakage current and count rate change had been observed up to a neutron fluence of 3x10 sup 1 sup 6 n/cm sup 2. The charge collection efficiency variations of neutron irradiated diamond spectrometer were studied ex situ under gamma-rays, beta-radiation and visible light excitation. Charge collection efficiency restoration up to 75% level and the NDD performance stabilization by extrinsic low-intensity visible light (550 nm

  10. Functional proteomics with new mass spectrometric and bioinformatics tools

    International Nuclear Information System (INIS)

    Kesners, P.W.A.

    2001-01-01

    A comprehensive range of mass spectrometric tools is required to investigate todays life science applications and a strong focus is on addressing the needs of functional proteomics. Application examples are given showing the streamlined process of protein identification from low femtomole amounts of digests. Sample preparation is achieved with a convertible robot for automated 2D gel picking, and MALDI target dispensing. MALDI-TOF or ESI-MS subsequent to enzymatic digestion. A choice of mass spectrometers including Q-q-TOF with multipass capability, MALDI-MS/MS with unsegmented PSD, Ion Trap and FT-MS are discussed for their respective strengths and applications. Bioinformatics software that allows both database work and novel peptide mass spectra interpretation is reviewed. The automated database searching uses either entire digest LC-MS n ESI Ion Trap data or MALDI MS and MS/MS spectra. It is shown how post translational modifications are interactively uncovered and de-novo sequencing of peptides is facilitated

  11. Determination of iodine to compliment mass spectrometric measurements

    International Nuclear Information System (INIS)

    Hohorst, F.A.

    1994-11-01

    The dose of iodine-129 to facility personnel and the general public as a result of past, present, and future activities at DOE sites is of continuing interest, WINCO received about 160 samples annually in a variety of natural matrices, including snow, milk, thyroid tissue, and sagebrush, in which iodine-129 is determined in order to evaluate this dose, Currently, total iodine and the isotopic ratio of iodine-127 to iodine-129 are determined by mass spectrometry. These two measurements determine the concentration of iodine-129 in each sample, These measurements require at least 16 h of mass spectrometer operator time for each sample. A variety of methods are available which concentrate and determine small quantities of iodine. Although useful, these approaches would increase both time and cost. The objective of this effort was to determine total iodine by an alternative method in order to decrease the load on mass spectrometry by 25 to 50%. The preparation of each sample for mass spectrometric analysis involves a common step--collection of iodide on an ion exchange bed. This was the focal point of the effort since the results would be applicable to all samples

  12. Surface acoustic wave nebulization facilitating lipid mass spectrometric analysis.

    Science.gov (United States)

    Yoon, Sung Hwan; Huang, Yue; Edgar, J Scott; Ting, Ying S; Heron, Scott R; Kao, Yuchieh; Li, Yanyan; Masselon, Christophe D; Ernst, Robert K; Goodlett, David R

    2012-08-07

    Surface acoustic wave nebulization (SAWN) is a novel method to transfer nonvolatile analytes directly from the aqueous phase to the gas phase for mass spectrometric analysis. The lower ion energetics of SAWN and its planar nature make it appealing for analytically challenging lipid samples. This challenge is a result of their amphipathic nature, labile nature, and tendency to form aggregates, which readily precipitate clogging capillaries used for electrospray ionization (ESI). Here, we report the use of SAWN to characterize the complex glycolipid, lipid A, which serves as the membrane anchor component of lipopolysaccharide (LPS) and has a pronounced tendency to clog nano-ESI capillaries. We also show that unlike ESI SAWN is capable of ionizing labile phospholipids without fragmentation. Lastly, we compare the ease of use of SAWN to the more conventional infusion-based ESI methods and demonstrate the ability to generate higher order tandem mass spectral data of lipid A for automated structure assignment using our previously reported hierarchical tandem mass spectrometry (HiTMS) algorithm. The ease of generating SAWN-MS(n) data combined with HiTMS interpretation offers the potential for high throughput lipid A structure analysis.

  13. Creating potentiometric surfaces from combined water well and oil well data in the midcontinent of the United States

    Science.gov (United States)

    Gianoutsos, Nicholas J.; Nelson, Philip H.

    2013-01-01

    For years, hydrologists have defined potentiometric surfaces using measured hydraulic-head values in water wells from aquifers. Down-dip, the oil and gas industry is also interested in the formation pressures of many of the same geologic formations for the purpose of hydrocarbon recovery. In oil and gas exploration, drillstem tests (DSTs) provide the formation pressure for a given depth interval in a well. These DST measurements can be used to calculate hydraulic-head values in deep hydrocarbon-bearing formations in areas where water wells do not exist. Unlike hydraulic-head measurements in water wells, which have a low number of problematic data points (outliers), only a small subset of the DST data measure true formation pressures. Using 3D imaging capabilities to view and clean the data, we have developed a process to estimate potentiometric surfaces from erratic DST data sets of hydrocarbon-bearing formations in the midcontinent of the U.S. The analysis indicates that the potentiometric surface is more readily defined through human interpretation of the chaotic DST data sets rather than through the application of filtering and geostatistical analysis. The data are viewed as a series of narrow, 400-mile-long swaths and a 2D viewer is used to select a subset of hydraulic-head values that represent the potentiometric surface. The user-selected subsets for each swath are then combined into one data set for each formation. These data are then joined with the hydraulic-head values from water wells to define the 3D potentiometric surfaces. The final product is an interactive, 3D digital display containing: (1) the subsurface structure of the formation, (2) the cluster of DST-derived hydraulic head values, (3) the user-selected subset of hydraulic-head values that define the potentiometric surface, (4) the hydraulic-head measurements from the corresponding shallow aquifer, (5) the resulting potentiometric surface encompassing both oil and gas and water wells, and (6

  14. CMP(O) tripodands: synthesis, potentiometric studies and extractions

    Energy Technology Data Exchange (ETDEWEB)

    Reinoso-Garcia, M.M.; Jaczewski, D.; Reinhoudt, D.N.; Verboom, W. [Twente Univ., Lab. of Supramolecular Chemistry and Technology, Mesa Research Institute for Nanotechnology, Enschede (Netherlands); Malinowska, E.; Pietrzak, M. [University of Technology, Dept. of Analytical Chemistry, Faculty of Chemistry, Warsaw (Poland); Hill, C. [CEA Valrho Site de Marcoule, Dept. Radiochimie et Procedes, 30 (France); Baa, J.; Gruner, B. [Institut of Organic Chemistry, Academy of Sciences of the Czech Republic, Prague (Czech Republic); Selucky, P. [Nuclear Research Institute REZ, CZ (Czech Republic); Gruttner, C. [Micromod Partikeltechnologie GmbH, Rostock (Germany)

    2006-10-15

    Ligand systems containing three carbamoyl-methyl-phosphonate (CMP) or -phosphine oxide (CMPO) moieties attached to a tripodal platform have been synthesized for metal complexation and subsequent extraction from HNO{sub 3} solutions. The incorporation into ion selective electrodes (ISE) and picrate extractions with Na{sup +}, K{sup +}, Ag{sup +}, Ca{sup 2+}, Cd{sup 2+}, Hg{sup 2+}, Pb{sup 2+}, Cu{sup 2+}, Eu{sup 3+} and Fe{sup 3+} shows that CMPO tripodand 3 is very selective for Eu{sup 3+} and forms a very stable complex (log{beta}{sub ML} = 28.3). Liquid-liquid extractions performed with Eu{sup 3+} and Am{sup 3+} show reasonable extraction properties of the CMP(O) tripodands 3, 11 and 13 in 1,1,2,2-tetra-chloro-ethane, while in 1-octanol for all tripodands studied the distribution coefficients are low. Upon addition of the synergistic agent hexa-brominated cobalt bis(dicarbollide) anion (bromo-COSAN) the distribution coefficients for Am{sup 3+} and Eu{sup 3+} extraction increase considerably for CMP(O) tripodands 3 and 4. Covalently linked COSAN only enhances the extraction of Am{sup 3+} and Eu{sup 3+} at 0.001-0.01 M HNO{sub 3}. The functionalization of dendrimer coated magnetic silica particles with CMP(O) tripodands led to very effective particles (31 and 32) for Am{sup 3+} and Eu{sup 3+} removal from 0.01 M HNO{sub 3} solutions. (authors)

  15. Cell surface groups of two picocyanobacteria strains studied by zeta potential investigations, potentiometric titration, and infrared spectroscopy.

    Science.gov (United States)

    Dittrich, Maria; Sibler, Sabine

    2005-06-15

    In order to clarify the role of picocyanobacteria in aquatic biogeochemical processes (e.g., calcite precipitation), cell surface properties need to be investigated. An experimental study of the cell surface characteristics of two Synechococcus-type unicellular autotrophic picocyanobacterial strains was carried out. One strain was isolated from Lake Plon and contained phycocyanin, the other strain came from Lago Maggiore and was rich in phycoerythrin. Potentiometric titrations were conducted to determine the different types of sites present on the bacteria cell walls. Infrared spectroscopy allowed characterization of the various functional groups (RNH(2), RCOOH, ROH, RPO(2)) and investigations of zeta potential provided insight into the isoelectrical points of the strains. Titrations reveal three distinct sites on the bacterial surfaces of phycocyanin- and phycoerythrin-rich strains with pK values of 4.8+/-0.3/5.0+/-0.2, 6.6+/-0.2/6.7+/-0.4, and 8.8+/-0.1/8.7+/-0.2, corresponding to carboxyl, phosphate, and amine groups with surface densities of 2.6+/-0.4/7.4+/-1.6 x 10(-4), 1.9+/-0.5/4.4+/-0.8 x 10(-4), and 2.5+/-0.4/4.8+/-0.7 x 10(-4) mol/g of dry bacteria. The deprotonation constants are similar to those of bacterial strains and site densities are also within an order of magnitude of other strains. The phycoerythrin-rich strain had a higher number of binding sites than the phycocyanin-rich strain. The results showed that picocyanobacteria may adsorb either calcium cations or carbonate anions and therefore strongly influence the biogeochemical cycling of calcite in pelagic systems.

  16. Vapor generation – atomic spectrometric techniques. Expanding frontiers through specific-species preconcentration. A review

    International Nuclear Information System (INIS)

    Gil, Raúl A.; Pacheco, Pablo H.; Cerutti, Soledad; Martinez, Luis D.

    2015-01-01

    This article reviews 120 articles found in SCOPUS and specific Journal cites corresponding to the terms ‘preconcentration’; ‘speciation’; ‘vapor generation techniques’ and ‘atomic spectrometry techniques’ in the last 5 years. - Highlights: • Recent advances in vapor generation and atomic spectrometry were reviewed. • Species-specific preconcentration strategies after and before VG were discussed. • New preconcentration and speciation analysis were evaluated within this framework. - Abstract: We review recent progress in preconcentration strategies associated to vapor generation techniques coupled to atomic spectrometric (VGT-AS) for specific chemical species detection. This discussion focuses on the central role of different preconcentration approaches, both before and after VG process. The former was based on the classical solid phase and liquid–liquid extraction procedures which, aided by automation and miniaturization strategies, have strengthened the role of VGT-AS in several research fields including environmental, clinical, and others. We then examine some of the new vapor trapping strategies (atom-trapping, hydride trapping, cryotrapping) that entail improvements in selectivity through interference elimination, but also they allow reaching ultra-low detection limits for a large number of chemical species generated in conventional VG systems, including complete separation of several species of the same element. This review covers more than 100 bibliographic references from 2009 up to date, found in SCOPUS database and in individual searches in specific journals. We finally conclude by giving some outlook on future directions of this field

  17. Vapor generation – atomic spectrometric techniques. Expanding frontiers through specific-species preconcentration. A review

    Energy Technology Data Exchange (ETDEWEB)

    Gil, Raúl A.; Pacheco, Pablo H.; Cerutti, Soledad [Área de Química Analítica, Facultad de Química Bioquímica y Farmacia, Universidad Nacional de San Luis, Ciudad de San Luis 5700 (Argentina); Instituto de Química de San Luis, INQUISAL, Centro Científico-Tecnológico de San Luis (CCT-San Luis), Consejo Nacional de Investigaciones Científicas y Universidad Nacional de San Luis, Ciudad de San Luis 5700 (Argentina); Martinez, Luis D., E-mail: ldm@unsl.edu.ar [Área de Química Analítica, Facultad de Química Bioquímica y Farmacia, Universidad Nacional de San Luis, Ciudad de San Luis 5700 (Argentina); Instituto de Química de San Luis, INQUISAL, Centro Científico-Tecnológico de San Luis (CCT-San Luis), Consejo Nacional de Investigaciones Científicas y Universidad Nacional de San Luis, Ciudad de San Luis 5700 (Argentina)

    2015-05-22

    This article reviews 120 articles found in SCOPUS and specific Journal cites corresponding to the terms ‘preconcentration’; ‘speciation’; ‘vapor generation techniques’ and ‘atomic spectrometry techniques’ in the last 5 years. - Highlights: • Recent advances in vapor generation and atomic spectrometry were reviewed. • Species-specific preconcentration strategies after and before VG were discussed. • New preconcentration and speciation analysis were evaluated within this framework. - Abstract: We review recent progress in preconcentration strategies associated to vapor generation techniques coupled to atomic spectrometric (VGT-AS) for specific chemical species detection. This discussion focuses on the central role of different preconcentration approaches, both before and after VG process. The former was based on the classical solid phase and liquid–liquid extraction procedures which, aided by automation and miniaturization strategies, have strengthened the role of VGT-AS in several research fields including environmental, clinical, and others. We then examine some of the new vapor trapping strategies (atom-trapping, hydride trapping, cryotrapping) that entail improvements in selectivity through interference elimination, but also they allow reaching ultra-low detection limits for a large number of chemical species generated in conventional VG systems, including complete separation of several species of the same element. This review covers more than 100 bibliographic references from 2009 up to date, found in SCOPUS database and in individual searches in specific journals. We finally conclude by giving some outlook on future directions of this field.

  18. Gas chromatographic/mass spectrometric determination of carbon isotope composition in unpurified samples: methamphetamine example.

    Science.gov (United States)

    Low, I A; Liu, R H; Legendre, M G; Piotrowski, E G; Furner, R L

    1986-10-01

    A gas chromatograph/quadrupole mass spectrometer system, operated in electron impact/selected ion monitoring mode, is used to determine the intensity ratio of the m/z 59 and the m/z 58 ions of the [C3H8N]+ fragment derived from methamphetamine samples synthesized with varying amounts of 13C-labeled methylamine. Crude products are introduced into the gas chromatograph without prior cleanup. The ratios measured were in excellent agreement with those calculated. A change in 0.25% use of 13C-methylamine is sufficient for product differentiation. The feasibility of using isotope labeling and subsequent mass spectrometric isotope ratio measurement as the basis of a compound tracing mechanism is discussed. Specifically, if methamphetamine samples manufactured from legal sources are asked to incorporate distinct 13C compositions, their sources can be traced when samples are diverted into illegal channels. Samples derived from illicit preparations can also be traced if the manufacturers of a precursor (methylamine in this case) incorporate distinct 13C compositions in their products.

  19. Mass spectrometric study of rhamnolipid biosurfactants and their interactions with cell membrane phospholipids

    Directory of Open Access Journals (Sweden)

    Pashynska V. A.

    2009-12-01

    Full Text Available Aim. To examine the formation of supramolecular complexes of biogenous rhamnolipids with membrane phospholipids that is considered as a molecular mechanism of the biosurfactants antimicrobial action. Method. In the present work rhamnolipid biosurfactant samples produced by Pseudomonas sp. PS-17 strain have been investigated by electrospray ionization mass spectrometry for the first time. Results. As a result of the study, characteristic mass spectra of the rhamnolipid samples were obtained, that can be used as reference spectra for mass spectrometric identification of the compounds in any biological or industrial samples. At the next stage of the experiments the pair systems, containing the biosurfactants and a membrane phospholipid dipalmitoylphosphatidylcholine, have been tested. The cationized noncovalent complexes of the rhamnolipids with the phospholipid were observed in the spectra. Conclusions. The results obtained testify to the consideration that rhamnolipids (similar to other membranotropic agents can form stable supramolecular complexes with membrane phospholipids that are able to evoke the biosurfactants antimicrobial action. A great potential of electrospray ionization mass spectrometry for the biosurfactants identification and study has been demonstrated in the work.

  20. Sequence-specific capture of protein-DNA complexes for mass spectrometric protein identification.

    Directory of Open Access Journals (Sweden)

    Cheng-Hsien Wu

    Full Text Available The regulation of gene transcription is fundamental to the existence of complex multicellular organisms such as humans. Although it is widely recognized that much of gene regulation is controlled by gene-specific protein-DNA interactions, there presently exists little in the way of tools to identify proteins that interact with the genome at locations of interest. We have developed a novel strategy to address this problem, which we refer to as GENECAPP, for Global ExoNuclease-based Enrichment of Chromatin-Associated Proteins for Proteomics. In this approach, formaldehyde cross-linking is employed to covalently link DNA to its associated proteins; subsequent fragmentation of the DNA, followed by exonuclease digestion, produces a single-stranded region of the DNA that enables sequence-specific hybridization capture of the protein-DNA complex on a solid support. Mass spectrometric (MS analysis of the captured proteins is then used for their identification and/or quantification. We show here the development and optimization of GENECAPP for an in vitro model system, comprised of the murine insulin-like growth factor-binding protein 1 (IGFBP1 promoter region and FoxO1, a member of the forkhead rhabdomyosarcoma (FoxO subfamily of transcription factors, which binds specifically to the IGFBP1 promoter. This novel strategy provides a powerful tool for studies of protein-DNA and protein-protein interactions.

  1. Vaporization of niobium dioxide by mass-effusion and mass-spectrometric methods

    International Nuclear Information System (INIS)

    Kamegashira, N.; Matsui, T.; Harada, M.; Naito, K.

    1981-01-01

    The congruence of the vaporization process of NbO, NbO 2 , Nb 12 O 29 and Nb 2 O 5 in the niobium-oxygen system was investigated from the phase change of the solid residue after vaporization, and it was observed that only the NbO 2 phase vaporizes congruently. The vapor pressures over NbO 2 (s) were measured by means of a combination of mass-effusion (weight loss measurement) and mass-spectrometric methods in the temperature range 1953-2323 K. By applying the second and the third law treatments of thermodynamics to the partial pressures of the gaseous species NbO 2 (g), NbO(g) and O(g), the enthalpies of vaporization for the reactions NbO 2 (s,1)=NbO 2 (g) and NbO 2 (s,1)=NbO(g)+O(g), were calculated. From these data the enthalpies of formation and the dissociation energies of NbO 2 (g) and NbO(g) were also determined. The uncertainties included in the third law treatment were discussed, and the results calculated by the third law treatment using the most reliable data available at present were presented. (orig.)

  2. Analysis of Endocrine Disrupting Pesticides by Capillary GC with Mass Spectrometric Detection

    Directory of Open Access Journals (Sweden)

    Svetlana Hrouzková

    2012-09-01

    Full Text Available Endocrine disrupting chemicals, among them many pesticides, alter the normal functioning of the endocrine system of both wildlife and humans at very low concentration levels. Therefore, the importance of method development for their analysis in food and the environment is increasing. This also covers contributions in the field of ultra-trace analysis of multicomponent mixtures of organic pollutants in complex matrices. With this fact conventional capillary gas chromatography (CGC and fast CGC with mass spectrometric detection (MS has acquired a real importance in the analysis of endocrine disrupting pesticide (EDP residues. This paper provides an overview of GC methods, including sample preparation steps, for analysis of EDPs in a variety of matrices at ultra-trace concentration levels. Emphasis is put on separation method, mode of MS detection and ionization and obtained limits of detection and quantification. Analysis time is one of the most important aspects that should be considered in the choice of analytical methods for routine analysis. Therefore, the benefits of developed fast GC methods are important.

  3. Lanthanide recognition: A Ho3+ potentiometric membrane sensor as a probe for determination of terazosin

    International Nuclear Information System (INIS)

    Ganjali, Mohammad Reza; Shams, Haniyeh; Faridbod, Farnoush; Hajiaghababaei, Leila; Norouzi, Parviz

    2009-01-01

    In this study, complexation of N'-(1-pyridin-2-ylmethylene)-2-furohydrazide (NFH) with some metal ions was investigated by conductometry and spectroscopy. Then, a Ho 3+ potentiometric membrane sensor was prepared based on the highly selective complexation between this ionophore and Ho 3+ . These new ionophores are more selective than the previously reported ones. In this work, for the first time, the proposed sensor was applied in indirect determination of the terazocine in its pharmaceutical formulation. The interest in constructing lanthanide sensors arises because they have similar ionic radii to calcium, but a higher charge density, which allows them to be used as probes to find the interactions between Ca 2+ and biologically important molecules.

  4. Direct potentiometric control of chloride-ion content in water coolant of nuclear reactors

    International Nuclear Information System (INIS)

    Moskvin, L.N.; Vilkov, N.Ya.; Krasnoperov, V.M.; Epimakhova, L.V.

    1979-01-01

    The work of automatic chloride measuring device designed for continuous determination of chloride-ion concentration in water coolants of nuclear power plants is investigated. A series of experiments have been performed to investigate a device with sensitive element in the form of potentiometric cell with two flowing porous metal silver electrodes (PSE), placed in series. A calibration circuit of chloride measuring devices and PSE is described. A comparison is made between the results obtained by means of automatic chloride measuring device and results of manual control of samples. A conclusion is drawn that automatic chloride measuring devices meet the requirements of nuclear power plants for methods and instruments of control of chloride-ions microconcentration. The development and implantation of automatic chloride-ion analizers will make the analytical control on nuclear power plants easier and make it possible to obtain more reliable information

  5. Functionalization of PVC membrane with ss oligonucleotides for a potentiometric biosensor.

    Science.gov (United States)

    Shishkanova, T V; Volf, R; Krondak, M; Král, V

    2007-05-15

    A novel application of a single stranded (ss) oligonucleotide as an active component of polymeric membrane in an ion-selective electrode (ISE) is described. The original oligonucleotides, oligo(dA)(15), modified by cholesterol, triphenylmethyl and hexadecyl derivatives, were immobilized into poly(vinyl chloride) (PVC) membrane using extraction protocol. In parallel, the adsorption protocol was used to immobilize unmodified oligo(dA)(15) on the PVC membrane based on tridodecylmethyammonium chloride (TDDMA(+)Cl(-)). Immobilization of ss oligonucleotide probe through spacer was more effective for the potentiometric detection of the hybridization between complementary oligonucleotides. It was found that cholesterol-oligo(dA)(15) modified membranes were sensitive toward complementary oligo(dT)(15) in the concentration range 2-80 nM at pH 7. An explanation for the detection mechanism is proposed.

  6. Potentiometric determination of uranium in simulated Purex Process solutions by acidiometry

    International Nuclear Information System (INIS)

    Cohen, V.H.; Matsuda, H.T.; Araujo, B.F. de; Araujo, J.A. de

    1983-01-01

    A potentiometric methods for sequential free acidity and uranium determination in simulated Purex Process solutions is described. An oxalate solution or a mixture of fluoride-oxalate pellets were used as complexing agent for free titration. Following this first equivalent point, uranium is determined-by indirect titration of H + liberated in the peruanate reaction. Some elements present in the standard fuel elements with a burn-up of 33.000 Mwd/t, neutron flux of 3,2 x 10 13 n.cm -2 .s -1 and cooling time of two years were considered as interfering elements in uranium analyses. As a substitute of Pu-IV, Th(NO 3 ) 4 solution was used. The method can be applied to aqueous and organic (TBP/diluent) solutions with 2% precision and 2% accuracy. (Autor) [pt

  7. Potentiometric determination of uranium in the presence of plutonium in Hsub(2)SOsub(4) medium

    International Nuclear Information System (INIS)

    Gopinath, N.; Rama Rao, G.A.; Manchanda, V.K.; Natarajan, P.R.

    1985-01-01

    The potentiometric determination of uranium is widely carried out in phosphoric acid medium to suppress the interferences of plutonium by complexation. Owing to the complexity of the recycling plutonium from the phosphate based waste involving manifold stages of separation, a method is proposed which does not use phosphoric acid. Uranium and plutonium are reduced to U(IV) and Pu(III) in IM Hsub(2)SOsub(4) by Ti(III), and NaNOsub(2) is chosen to selectively oxidize Pu(III) and the excess of Ti(III). The unreacted NaNOsub(2) is destroyed by sulphamic acid and excess Fe(III) is added following dilution. The euqivalent amount of Fe(II) thus liberated is titrated against standard Ksub(2)Crsub(2)Osub(7). RSD obtained for the determination of uranium (1-2 mg) is 0.3% with plutonium present up to 4.0 mg. (author)

  8. Potentiometric stripping analysis of lead and cadmium leaching from dental prosthetic materials and teeth

    Directory of Open Access Journals (Sweden)

    GORAN M. NIKOLIC

    2004-07-01

    Full Text Available Potentiometric stipping analysis (PSA was applied for the determination of lead and cadmium leaching from dental prosthetic materials and teeth. The soluble lead content in finished dental implants was found to be much lower than that of the individual components used for their preparation. Cadmium was not detected in dental implants and materials under the defined conditions. The soluble lead and cadmium content of teeth was slightly lower than the lead and cadmium content in whole teeth (w/w reported by other researchers, except in the case of a tooth with removed amalgam filling. The results of this work suggest that PSA may be a good method for lead and cadmium leaching studies for investigation of the biocompatibility of dental prosthetic materials.

  9. Paper-based potentiometric pH sensor using carbon electrode drawn by pencil

    Science.gov (United States)

    Kawahara, Ryotaro; Sahatiya, Parikshit; Badhulika, Sushmee; Uno, Shigeyasu

    2018-04-01

    A flexible and disposable paper-based pH sensor fabricated with a pencil-drawn working electrode and a Ag/AgCl paste reference electrode is demonstrated for the first time to show pH response by the potentiometric principle. The sensor substrate is made of chromatography paper with a wax-printed hydrophobic area, and various types of carbon pencils are tested as working electrodes. The pH sensitivities of the electrodes drawn by carbon pencils with different hardnesses range from 16.5 to 26.9 mV/pH. The proposed sensor is expected to be more robust against shape change in electrodes on a flexible substrate than other types of chemiresistive/amperometric pH sensors.

  10. Open ISEmeter: An open hardware high-impedance interface for potentiometric detection

    Energy Technology Data Exchange (ETDEWEB)

    Salvador, C.; Carbajo, J.; Mozo, J. D., E-mail: jdaniel.mozo@diq.uhu.es [Applied Electrochemistry Laboratory, Faculty of Experimental Sciences, University of Huelva, Av. 3 de Marzo s/n., 21007 Huelva (Spain); Mesa, M. S.; Durán, E. [Department of Electronics Engineering, Computers and Automatic, ETSI, University of Huelva, Campus de La Rabida, 21810 Huelva (Spain); Alvarez, J. L. [Department of Information Technologies, ETSI, University of Huelva, Campus de La Rabida, 21810 Huelva (Spain)

    2016-05-15

    In this work, a new open hardware interface based on Arduino to read electromotive force (emf) from potentiometric detectors is presented. The interface has been fully designed with the open code philosophy and all documentation will be accessible on web. The paper describes a comprehensive project including the electronic design, the firmware loaded on Arduino, and the Java-coded graphical user interface to load data in a computer (PC or Mac) for processing. The prototype was tested by measuring the calibration curve of a detector. As detection element, an active poly(vinyl chloride)-based membrane was used, doped with cetyltrimethylammonium dodecylsulphate (CTA{sup +}-DS{sup −}). The experimental measures of emf indicate Nernstian behaviour with the CTA{sup +} content of test solutions, as it was described in the literature, proving the validity of the developed prototype. A comparative analysis of performance was made by using the same chemical detector but changing the measurement instrumentation.

  11. Experiments for quick and accurate thorium assay by means of potentiometric end point determination

    International Nuclear Information System (INIS)

    Mainka, E.; Coerdt, W.

    1978-10-01

    Two methods are described which allow quick thorium assay easily to be automated. In the potentiometric titration with NaF the ion sensitive fluoride electrode is used as the indicator. The analysis can be performed for pH values 3 to 4. Th(OH) 4 precipitation must be avoided although the acidity of the solution must not be too high since otherwise erroneous measurements will be obtained. In the complexometric thorium assay EDTA is used for titration and the indicator is the copper sensitive electrode. This method offers the advantage that the analysis can be performed in the presence of large amounts of uranium, which is excluded under the NaF method. (orig.) [de

  12. Potentiometric determination of uranium in simulated Purex Process solutions by acidiometry

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, V H; Matsuda, H T; Araujo, B.F. de; Araujo, J.A. de

    1984-01-01

    A potentiometric methods for sequential free acidity and uranium determination in simulated Purex Process solutions is described. An oxalate solution or a mixture of fluoride-oxalate pellets were used as complexing agent for free titration. Following this first equivalent point, uranium is determined-by indirect titration of H/sup +/ liberated in the peruanate reaction. Some elements present in the standard fuel elements with a burn-up of 33.000 Mwd/t, neutron flux of 3,2 x 10/sup 13/n.cm/sup -2/.s/sup -1/ and cooling time of two years were considered as interfering elements in uranium analyses. As a substitute of Pu-IV, Th(NO/sub 3/)/sub 4/ solution was used. The method can be applied to aqueous and organic (TBP/diluent) solutions with 2% precision and 2% accuracy. (Autor).

  13. Enantioanalysis of S-deprenyl using enantioselective, potentiometric membrane electrodes based on C60 derivatives

    International Nuclear Information System (INIS)

    Stefan-van Staden, Raluca-Ioana

    2010-01-01

    Enantioselective, potentiometric membrane electrodes based on (1,2-methanofullerene C 60 )-61-carboxylic acid, diethyl (1,2-methanofullerene C 60 )-61-61-dicarboxylate and tert-butyl (1,2-methanofullerene C 60 )-61-carboxylic acid were proposed for the enantioanalysis of S-deprenyl in pharmaceutical compounds. Molecular modeling calculations were performed to prove the reliability of the proposed electrodes. The different characteristics involved in this analysis were explained, namely (i) the stability of each molecule using total energy, hardness and dipole moment, and (ii) the explanation of the mechanism of interaction using intermolecular forces (moderate hydrogen bond interactions), atomic charges and electrostatic potential. Electronic structures as well as molecular interaction have been investigated using Hartree-Fock theory, 3-21G(*) basis set. Stability and feasibility of all the generated structures were supported by their respective energy minima and fundamental frequencies.

  14. Open ISEmeter: An open hardware high-impedance interface for potentiometric detection

    International Nuclear Information System (INIS)

    Salvador, C.; Carbajo, J.; Mozo, J. D.; Mesa, M. S.; Durán, E.; Alvarez, J. L.

    2016-01-01

    In this work, a new open hardware interface based on Arduino to read electromotive force (emf) from potentiometric detectors is presented. The interface has been fully designed with the open code philosophy and all documentation will be accessible on web. The paper describes a comprehensive project including the electronic design, the firmware loaded on Arduino, and the Java-coded graphical user interface to load data in a computer (PC or Mac) for processing. The prototype was tested by measuring the calibration curve of a detector. As detection element, an active poly(vinyl chloride)-based membrane was used, doped with cetyltrimethylammonium dodecylsulphate (CTA"+-DS"−). The experimental measures of emf indicate Nernstian behaviour with the CTA"+ content of test solutions, as it was described in the literature, proving the validity of the developed prototype. A comparative analysis of performance was made by using the same chemical detector but changing the measurement instrumentation.

  15. Determination of arsenate and organic arsenic via potentiometric titration of its heteropoly anions.

    Science.gov (United States)

    Metelka, R; Slavíková, S; Vytras, K

    2002-08-16

    Determination of arsenate based on its conversion to molybdoarsenate heteropoly anions followed by potentiometric titration is described. The titration is realized on the ion-pairing principle using cetylpyridinium chloride (or an analogous titrant containing a lipophilic cation), and is monitored by a carbon paste electrode, although other liquid-polymeric membrane-based electrodes can also be used. Calibration plots of the titrant end-point consumption versus concentration of arsenic were constructed and used to evaluate the content of arsenic in aqueous samples. The method could be applied in the analyses of samples with quite low arsenic content (amounts approximately 10 mug As in 50 cm(3) could be titrated). Organic arsenic was determined analogously after the Schöniger combustion of the sample and conversion of its arsenic to arsenate.

  16. The binding of aluminum to mugineic acid and related compounds as studied by potentiometric titration.

    Science.gov (United States)

    Yoshimura, Etsuro; Kohdr, Hicham; Mori, Satoshi; Hider, Robert C

    2011-08-01

    The phytosiderophores, mugineic acid (MA) and epi-hydroxymugineic acid (HMA), together with a related compound, nicotianamine (NA), were investigated for their ability to bind Al(III). Potentiometric titration analysis demonstrated that MA and HMA bind Al(III), in contrast to NA which does not under normal physiological conditions. With MA and HMA, in addition to the Al complex (AlL), the protonated (AlLH) and deprotonated (AlLH(-1)) complexes were identified from an analysis of titration curves, where L denotes the phytosiderophore form in which all the carboxylate functions are ionized. The equilibrium formation constants of the Al(III) phytosiderophore complexes are much smaller than those of the corresponding Fe(III) complexes. The higher selectivity of phytosiderophores for Fe(III) over Al(III) facilitates Fe(III) acquisition in alkaline conditions where free Al(III) levels are higher than free Fe(III) levels.

  17. Potentiometric Determination of Phytic Acid and Investigations of Phytate Interactions with Some Metal Ions.

    Science.gov (United States)

    Marolt, Gregor; Pihlar, Boris

    2015-01-01

    Determination of correct amount (concentration) of phytic acid is of vital importance when dealing with protonation and/or metal complexation equilibria. A novel approach for precise and reliable assay of phytic acid, based on the difference between end points by potentiometric titration, has been presented. Twelve phytic acid protons are classified into three groups of acidity, which enables detection of 2 to 3 distinct equivalent points (EPs) depending on experimental conditions, e.g. counter-ion concentration. Using the differences between individual EPs enables correct phytate determination as well as identification of potential contamination and/or determination of initial protonation degree. Impact of uncertainty of phytate amount on the calculation of protonation constants has been evaluated using computer simulation program (Hyperquad2013). With the analysis of titration curves different binding sites on phytate ligand have been proposed for complexation of Ca2+ and Fe3+ ions.

  18. Liquid membrane ion-selective electrodes for potentiometric dosage of coper and nickel

    Directory of Open Access Journals (Sweden)

    MARIA PLENICEANY

    2005-02-01

    Full Text Available This paper presents experimental and theoretical data regarding the preparation and characterization of three liquid-membrane electrodes, which have not been mentioned in the specialized literature so far. The active substances, the solutions of which in nitrobenzene formed the membranes on a graphite rod, are simple complex combinations of Cu(II and Ni(II ions with an organic ligand belonging to the Schiff base class: N-[2-thienylmethilidene]-2-aminoethanol (TNAHE. The Cu2+ -selective and Ni2+ -selective electrodes were used to determine the copper and nickel ions in aqueous solutions, both by direct potentiometry and by potentiometric titration with EDTA. They were also used for the determination of Cu2+ and Ni2+ ions in industrial waters by direct potentiometry.

  19. Sequential potentiometric determination of uranium and plutonium in a single aliquot

    International Nuclear Information System (INIS)

    Rao, V.K.; Charyulu, M.M.; Natarajan, P.R.

    1983-01-01

    A method is reported for sequential potentiometric determination of uranium and plutonium present is an aliquot. Plutonium is first determined by oxidizing it to the hexavalent state with perchloric acid followed by iron(II) reduction and titration of excess ferrous iron with chromium(VI). Uranium is subsequently determined by reduction to the quadrivalent state using titanium(III) and titration with vanadium(V). The interference of plutonium and iron(II) is eliminated by the addition of a mixture containing sulfamic acid, nitric acid, and molybdenum(VI). The results of the analysis of mixture containing 3-5 mg quantities of uranium and plutonium are reliable with errors less than 0.3% and 0.2%, respectively. The application of the method for the analysis of mixtures containing various amounts of uranium and plutonium has been examined. (author)

  20. A new potentiometric determination of hydrazine in the presence of uranium(IV)

    International Nuclear Information System (INIS)

    Singh, N.S.; Mohan, S.V.

    1996-01-01

    The present method describes the determination of hydrazine by making use of potentiometric titration technique. The underlying principle is back titration of unreacted excess cerium remaining after the complete oxidation of hydrazine. Standardized ferrous ammonium sulfate was used for titration. This method was applied to 'real samples' generated from a nuclear reprocessing plant wherein control of hydrazine is of paramount importance. The interference of U(IV), Cr(III), U(VI), nitrite, and chloride was studied and of all these ions the way to eliminate the interference of U(IV) was only attempted. The relative standard deviations (RSD) for synthetic as well as 'real samples' were determined. The method gives RSD of less than 1% in the range of 1 mg to 20 mg of hydrazine. The error in the range 3 mg to 17 mg was found to be less than 1%. (author). 5 refs., 3 tabs

  1. A potentiometric titration method for the crystallization of drug-like organic molecules.

    Science.gov (United States)

    Du-Cuny, Lei; Huwyler, Jörg; Fischer, Holger; Kansy, Manfred

    2007-09-05

    It is generally accepted, that crystalline solids representing a low energy polymorph should be selected for development of oral dosage forms. As a consequence, efficient and robust procedures are needed at an early stage during drug discovery to prepare crystals from drug-like organic molecules. In contrast to the use of supersaturated solutions, we present a potentiometric crystallization procedure where saturated solutions are prepared in a controlled manner by pH-titration. Crystallization is carried out under defined conditions using the sample concentration and experimental pK(a) values as input parameters. Crystals of high quality were obtained for 11 drugs selected to demonstrate the efficiency and applicability of the new method. Technical improvements are suggested to overcome practical limitations and to enhance the possibility of obtaining crystals from molecules in their uncharged form.

  2. Potentiometric studies on mixed-ligand chelates of uranyl ion with carboxylic acid phenolic acids

    International Nuclear Information System (INIS)

    Bandiwadekar, S.P.; Chavar, A.M.

    1988-01-01

    Mixed ligand complexes of UO 2 2+ with bidentate carboxylic and phenolic acids have been studied potentiometrically at 30 ± 0.1degC and μ=0.2M (NaClO 4 ). 1:1 and 1:2 complexes of UO 2 2+ with phthalic acid (PTHA), maleic acid (MAE), malonic acid (MAL), quinolinic acid (QA), 5-sulphosalicylic acid (5-SSA), salicylic acid (SA), and only 1:1 complexes in the case of mandelic acid (MAD) have been detected. The formation of 1:1:1 mixed ligand complexes has been inferred from simultaneous equilibria in the present study. The values of ΔlogK, Ksub(DAL), Ksub(2LA) or Ksub(2AL) for the ternary complexes have been calculated. The stabilities of mixed ligand complexes depend on the size of the chelate ring and the stabilities of the binary complexes. (author). 15 refs

  3. Atomic absorption spectrometric determination of mineral elements in mammalian bones

    International Nuclear Information System (INIS)

    Udoh, Anthony P.

    2000-01-01

    The phosphorus content of the major bones of male and female selected mammals was determined using the yellow vanadomolybdate colorimetric method. For each animal, the bone with the highest phosphorus content was used as pilot sample. Varying concentrations of strontium were added to solutions of the ashed pilot samples to minimize phosphorus interference in the determination of calcium and magnesium using flame atomic absorption spectrophotometry operated on the air-acetylene mode. At least 6,000 ppm (0.6%) of strontium was required to give optimum results for calcium. The amount of magnesium obtained from the analysis was not affected by the addition of strontium. With the incorporation of strontium in the sample solution, all elements of interest can be determined in the same sample solution. Based on this, a procedure is proposed for the determination of calcium and other elements in bones. Average recoveries of spiked calcium and magnesium were 97.85% and 98.16%, respectively at the 95% confidence level. The coefficients of variation obtained for replicate determinations using one of the samples were 0.00% for calcium, lead and sodium, 2.93% for magnesium, 3.27% for iron and 3.92% for zinc at the concentration levels found in that sample. Results from the proposed procedure compared well with those from classical chemical methods at the 95% confidence level. It is evident that calcium phosphorus, magnesium and sodium which are the most abundant elements in the bones are distributed in varying amounts both in the different types of bones and different animal species, although the general trend is Ca > P > Na > Mg for each bone considered. The calcium - phosphorus ratio is generally 3:1. The work set out to propose an atomic absorption spectrometric method for the multi-element analysis of mammalian bones with a single sample preparation and to study the distribution pattern of these elements in the bones. (Author)

  4. Interpretation of Spectrometric Measurements of Active Geostationary Satellites

    Science.gov (United States)

    Bedard, D.; Wade, G.

    2014-09-01

    Over 5000 visible near-infrared (VNIR) spectrometric measurements of active geostationary satellites have been collected with the National Research Council (NRC) 1.8m Plaskett telescope located at the Dominion Astrophysical Observatory (DAO) in Victoria, Canada. The objective of this ongoing experiment is to study how reflectance spectroscopy can be used to reliably identify specific material types on the surface of artificial Earth-orbiting objects. Active geostationary satellites were selected as the main subjects for this experiment since their orientation is stable and can be estimated to a high-level of confidence throughout a night of observation. Furthermore, for most geostationary satellites, there is a wide variety of sources that can provide some level of information as to their external surface composition. Notwithstanding the high number of measurements that have been collected to date, it was assumed that the experimenters would have a much greater success rate in material identification given the choice experimental subjects. To date, only the presence of aluminum has been confidently identified in some of the reflectance spectra that have been collected. Two additional material types, namely photovoltaic cells and polyimide film, the first layer of multi-layer insulation (MLI), have also been possibly identified. However uncertainties in the reduced spectral measurements prevent any definitive conclusion with respect to these materials at this time. The surprising lack of results with respect to material identification have forced the experimenters to use other data interpretation methods to characterize the spectral scattering characteristics of the studied satellites. The results from this study have already led to improvements in the ways that reflectance spectra from spacecraft are collected and analysed. Equally important, the data interpretation techniques elaborated over the course of this experiment will also serve to increase the body of

  5. The application of hydrogen-palladium electrode for potentiometric acid-base determinations in tetrahydrofuran

    Directory of Open Access Journals (Sweden)

    Jokić Anja B.

    2013-01-01

    Full Text Available The application of the hydrogen-palladium electrode (H2/Pd as the indicator electrode for the determination of relative acidity scale (Es, mV of tetrahydrofuran (THF and the potentiometric titrations of acids in this solvent was investigated. The relative acidity scale tetrahydrofuran was determined from the difference half-neutralization potentials of perchloric acid and tetrabutylammonium hydroxide (TBAH, which were measured by using both H2/Pd-SCE and glass-SCE electrode pairs. The experimentally obtained value of Es scale THF with a H2/Pd-SCE electrode pair was 1155 mV, and those obtained with glass-SCE electrode pair 880 mV. By using a H2/Pd indicator electrode, the individual acids (benzoic acid, palmitic acid, maleic acid, acetyl acetone, α-naphthol and two component acid mixtures (benzoic acid + α-naphthol, palmitic acid + α-naphthol, maleic acid + α-naphthol and maleic acid + ftalic acid were titrated with a standard solution of TBAH. In addition, sodium methylate and potassium hydroxide proved to be very suitable titrating agents for titrating of the individual acids and the acids in mixtures, respectively. The relative error of the determination of acids in mixture was less than 3%. The results are in agreement with those obtained by a conventional glass electrode. The advantages of H2/Pd electrode over a glass electrode in potentiometric acid-base determinations in tetrahydrofuran lie in the following: this electrode gives wider relative acidity scale THF, higher the potential jumps at the titration end-point and relatively fast response time; furthermore, it is very durable, simple to prepare and can be used in the titrations of small volumes. [Projekat Ministarstva nauke Republike Srbije, br.172051

  6. Potentiometric Urea Biosensor Based on an Immobilised Fullerene-Urease Bio-Conjugate

    Directory of Open Access Journals (Sweden)

    Kasra Saeedfar

    2013-12-01

    Full Text Available A novel method for the rapid modification of fullerene for subsequent enzyme attachment to create a potentiometric biosensor is presented. Urease was immobilized onto the modified fullerene nanomaterial. The modified fullerene-immobilized urease (C60-urease bioconjugate has been confirmed to catalyze the hydrolysis of urea in solution. The biomaterial was then deposited on a screen-printed electrode containing a non-plasticized poly(n-butyl acrylate (PnBA membrane entrapped with a hydrogen ionophore. This pH-selective membrane is intended to function as a potentiometric urea biosensor with the deposition of C60-urease on the PnBA membrane. Various parameters for fullerene modification and urease immobilization were investigated. The optimal pH and concentration of the phosphate buffer for the urea biosensor were 7.0 and 0.5 mM, respectively. The linear response range of the biosensor was from 2.31 × 10−3 M to 8.28 × 10−5 M. The biosensor’s sensitivity was 59.67 ± 0.91 mV/decade, which is close to the theoretical value. Common cations such as Na+, K+, Ca2+, Mg2+ and NH4+ showed no obvious interference with the urea biosensor’s response. The use of a fullerene-urease bio-conjugate and an acrylic membrane with good adhesion prevented the leaching of urease enzyme and thus increased the stability of the urea biosensor for up to 140 days.

  7. Potentiometric determination of trace amounts of volatile thiols in natural gas

    International Nuclear Information System (INIS)

    Farroha, S.M.; Habboush, A.E.; Kurthab, S.Y.

    1986-01-01

    A potentiometric titration method was developed for the determination of volatile thiols in natural gas. An apparatus was devised for the quantitative absorption of volatile thiols. The measurements were performed in an ethanolic ammonium buffer solution containing a known amount of silver nitrate as supporting electrolyte. The excess silver was precipitated by a known amount of potassium iodide. The excess of iodide was back titrated potentiometrically with a standard solution of silver nitrate. The direct titration of the excess silver ions with a standard solution of potassium iodide gave a poor accuracy compared with the back titration method. Iodide selective electrode was employed as an indicator electrode and a silver-silver chloride electrode as reference electrode. The accuracy and reproducibility of the method were established by preparing several synthetic samples in which ethanthiol containing from 346.61 to 12.11 μUg mercaptan sulfur was taken as standard nitrogen as carrier gas with an optimum flow rate of 31.5 L/hr. The results obtained expressed in the form of Grans plot showed an error ranging from 0.16 to 2.39% by weight and the relative standard deviation did not exceed 2.20%. The amount of mercaptan sulfur determined in Iraqi natural gas taken directly in a cylinder from Dora refinery, Baghdad, Iraq, and after six months of storage we 23.15 Ug/L and 21.25 Ug/L respectively with a relative standard deviation not exceeded 1%. The interferences of hydrogen sulfide could be eliminated by absorption in cadimium acetate containing solution. Other sulfur containing compounds e.g. disulfides, sulfoxides which may be present in natural gas do not interfere with the analysis

  8. Highly selective potentiometric and colorimetric determinations of cobalt (II) ion using thiazole based ligands.

    Science.gov (United States)

    Singhal, Divya; Singh, Ashok Kumar; Upadhyay, Anjali

    2014-12-01

    New PVC-membrane electrodes were prepared by using 2-((thiazol-2-ylimino)methyl)phenol (L1) and 2-((thiazol-2-ylamino)methyl)phenol (L2) and explored as Co(II) selective electrodes. The effect of various plasticizers and anion excluder was studied in detail and improved performance was observed. It was found that the electrode based on L1 shows better response characteristics in comparison to L2. Optimum performance was observed for the membrane electrode having a composition of L1:NaTPB:DBP:PVC≡2:8:78:62 (w/w, mg). The performance of PME based on L1 was compared with that of CGE. The electrodes exhibit Nernstian slope for Co(II) ions with a limit of detection of 6.91×10(-7) mol L(-1) for PME and 7.94×10(-8) mol L(-1) for CGE. The response time for PME and CGE was found to be 15s and 12 s respectively. The potentiometric responses are independent in the pH range 3.0-9.0 for CGE. The CGE could be used for a period of 90 days. The CGE was used as an indicator electrode in potentiometric titration of EDTA with Co(2+) ion. Further the selectivity of the L1 and L2 was also confirmed by the UV-vis and colorimetric studies and found that L1 is more selective for Co(II) ion. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. A selective potentiometric copper (II) ion sensor based on the functionalized ZnO nanorods.

    Science.gov (United States)

    Khun, K; Ibupoto, Z H; Liu, X; Nur, O; Willander, M; Danielsson, B

    2014-09-01

    In this work, ZnO nanorods were hydrothermally grown on the gold-coated glass substrate and characterized by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) techniques. The ZnO nanorods were functionalized by two different approaches and performance of the sensor electrode was monitored. Fourier transform infrared spectroscopy (FTIR) was carried out for the confirmation of interaction between the ionophore molecules and ZnO nanorods. In addition to this, the surface of the electrode was characterized by X-ray photoelectron spectroscopy (XPS) showing the chemical and electronic state of the ionophore and ZnO nanorod components. The ionophore solution was prepared in the stabilizer, poly vinyl chloride (PVC) and additives, and then functionalized on the ZnO nanorods that have shown the Nernstian response with the slope of 31 mV/decade. However, the Cu2+ ion sensor was fabricated only by immobilizing the selective copper ion ionophore membrane without the use of PVC, plasticizers, additives and stabilizers and the sensor electrode showed a linear potentiometric response with a slope of 56.4 mV/decade within a large dynamic concentration range (from 1.0 x 10(-6) to 1.0 x 10(-1) M) of copper (II) nitrate solutions. The sensor showed excellent repeatability and reproducibility with response time of less than 10 s. The negligible response to potentially interfering metal ions such as calcium (Ca2+), magnesium (Mg2+), potassium (K+), iron (Fe3+), zinc (Zn2+), and sodium (Na+) allows this sensor to be used in biological studies. It may also be used as an indicator electrode in the potentiometric titration.

  10. A novel approach for high precision rapid potentiometric titrations: application to hydrazine assay.

    Science.gov (United States)

    Sahoo, P; Malathi, N; Ananthanarayanan, R; Praveen, K; Murali, N

    2011-11-01

    We propose a high precision rapid personal computer (PC) based potentiometric titration technique using a specially designed mini-cell to carry out redox titrations for assay of chemicals in quality control laboratories attached to industrial, R&D, and nuclear establishments. Using this technique a few microlitre of sample (50-100 μl) in a total volume of ~2 ml solution can be titrated and the waste generated after titration is extremely low comparing to that obtained from the conventional titration technique. The entire titration including online data acquisition followed by immediate offline analysis of data to get information about concentration of unknown sample is completed within a couple of minutes (about 2 min). This facility has been created using a new class of sensors, viz., pulsating sensors developed in-house. The basic concept in designing such instrument and the salient features of the titration device are presented in this paper. The performance of the titration facility was examined by conducting some of the high resolution redox titrations using dilute solutions--hydrazine against KIO(3) in HCl medium, Fe(II) against Ce(IV) and uranium using Davies-Gray method. The precision of titrations using this innovative approach lies between 0.048% and 1.0% relative standard deviation in different redox titrations. With the evolution of this rapid PC based titrator it was possible to develop a simple but high precision potentiometric titration technique for quick determination of hydrazine in nuclear fuel dissolver solution in the context of reprocessing of spent nuclear fuel in fast breeder reactors. © 2011 American Institute of Physics

  11. Synthesis, spectral, thermal, potentiometric and antimicrobial studies of transition metal complexes of tridentate ligand

    Directory of Open Access Journals (Sweden)

    Sarika M. Jadhav

    2014-01-01

    Full Text Available A series of metal complexes of Cu(II, Ni(II, Co(II, Fe(III and Mn(II have been synthesized with newly synthesized biologically active tridentate ligand. The ligand was synthesized by condensation of dehydroacetic acid (3-acetyl-6-methyl-(2H pyran-2,4(3H-dione or DHA, o-phenylene diamine and fluoro benzaldehyde and characterized by elemental analysis, molar conductivity, magnetic susceptibility, thermal analysis, X-ray diffraction, IR, 1H-NMR, UV–Vis spectroscopy and mass spectra. From the analytical data, the stoichiometry of the complexes was found to be 1:2 (metal:ligand with octahedral geometry. The molar conductance values suggest the non-electrolyte nature of metal complexes. The IR spectral data suggest that the ligand behaves as a dibasic tridentate ligand with ONN donor atoms sequence towards central metal ion. Thermal behaviour (TG/DTA and kinetic parameters calculated by the Coats–Redfern and Horowitz–Metzger method suggest more ordered activated state in complex formation. To investigate the relationship between stability constants of metal complexes and antimicrobial activity, the dissociation constants of Schiff bases and stability constants of their binary metal complexes have been determined potentiometrically in THF–water (60:40% solution at 25 ± 1 °C and at 0.1 M NaClO4 ionic strength. The potentiometric study suggests 1:1 and 1:2 complexation. Antibacterial and antifungal activities in vitro were performed against Staphylococcus aureus, Escherichia coli and Aspergillus niger, Trichoderma, respectively. The stability constants of the metal complexes were calculated by the Irving–Rosotti method. A relation between the stability constant and antimicrobial activity of complexes has been discussed. It is observed that the activity enhances upon complexation and the order of antifungal activity is in accordance with stability order of metal ions.

  12. Potentiometric titration of uranium reduced by chromic salts in chloridic solutions; Titulacao potenciometrica de uranio reduzido por sais cromosos em solucoes cloridricas

    Energy Technology Data Exchange (ETDEWEB)

    Coutinho, C M.C.; Bastos, E T.R.

    1986-06-01

    The utilization of chromic salts for reducing the uranium (VI) from chloridic solutions, for potentiometric dosage is described. This method is used in the range of 0,002 to 1,0 M of uranium. (C.G.C.).

  13. Validation of analytical procedure of quantitative determination of 5,7-bis(meta-nitrophenylamino-4,6-dinitrobenzofuroxan by potentiometric titration

    Directory of Open Access Journals (Sweden)

    R. Sh. Markhabullina

    2014-01-01

    Full Text Available A new method of quantitative determination of the substance of 5,7-bis(meta-nitrophenylamino-4,6-dinitrobenzofuroxan using potentiometric titration method is developed. The method has high precision, reliability and sensitivity.

  14. Significance of Airborne Gamma-ray spectrometric data of Umm bisilla Area, central Eastern Desert, Egypt

    Energy Technology Data Exchange (ETDEWEB)

    Rabie, S I [Nuclear materials authority, Maadi, Cairo, (Egypt)

    1995-10-01

    Umm bisilla area, located in the Central Eastern Desert of Egypt, consists mainly of basement rocks. The present investigation of the airborne spectrometric data is to define the meaningful anomalies from the raw data by applying the significance factor techniques, by calculating the significant radioactive provinces. Determination of the gross structural pattern and broad variations in composition of the crystalline basement, to define the relationships between the tectonic features of the area as interpreted from aeromagnetic data, with the significant anomalies revealed from spectrometric data was carried out through the application of different magnetic techniques. Five significant uraniferous zones were detected associated with Umm Bisilla granite, amphibolite, and grey granite. The intersection of the structural lineaments interpreted from aeromagnetic data illustrated good correlation with the significant uranium anomalous zones interpreted from spectrometric data, and indicated that the concentration is structurally. 15 figs.

  15. Low-activity spectrometric gamma-ray logging technique for delineation of coal/rock interfaces in dry blast holes

    International Nuclear Information System (INIS)

    Asfahani, J.; Borsaru, M.

    2007-01-01

    A low-activity spectrometric gamma-ray logging technique is proposed in this paper as a sensitive tool for the delineation of coal/rock interfaces in dry blast holes. The advantages and superiority of this technique over traditional micro-density non-spectrometric gamma-ray tools are demonstrated

  16. Spectrometric methods for the determination of chlorine in crude oil and petroleum derivatives — A review

    International Nuclear Information System (INIS)

    Doyle, Adriana; Saavedra, Alvaro; Tristão, Maria Luiza B.; Mendes, Luiz A.N.; Aucélio, Ricardo Q.

    2013-01-01

    Chlorine determination in crude oil is made in order to guarantee that the oil does not contain levels of this element that might cause damages in the oil processing equipment. In petroleum products, the determination of chlorine is made, for instance, to evaluate if there are proper concentrations of organochloride compounds, which are used as additives. Such determinations are currently performed following official guidelines from the ASTM International and from the United States Environmental Protection Agency as well as protocols indicated by the Universal Oil Products. X-ray fluorescence spectroscopy plays an important role in many of these official methods. In contrast, other spectrometric methods based on optical and mass detection are plagued by limitations related to both the fundamental characteristics of non-metals and to the complex sample matrices, which reflects in the small number of articles devoted to these applications. In this review, the current status of the spectrometric methods, especially the role played by X-ray fluorescence spectrometry, is evaluated in terms of the determination of chlorine in crude oil and petroleum derivatives. Comparison of the performance of the methods, limitations and potential new approaches to ensure proper spectrometric determinations of chlorine is indicated. - Highlights: • Critical evaluation of spectrometric methods for chlorine in petroleum products. • Reviews on element determination in petroleum have not address the case of chlorine. • Peculiarities of the spectrometric determination of Cl in petroleum are discussed. • The spectrometric approaches are detailed and compared to the official methods. • New trends in chlorine determination in petroleum products are indicated

  17. Mass Spectrometric Characteristics of Prenylated Indole Derivatives from Marine-Derived Penicillium sp. NH-SL.

    Science.gov (United States)

    Ding, Hui; Ding, Wanjing; Ma, Zhongjun

    2017-03-22

    Two prenylated indole alkaloids were isolated from the ethyl acetate extracts of a marine-derived fungus Penicillium sp. NH-SL and one of them exhibited potent cytotoxic activity against mouse hepa 1c1c7 cells. In order to detect other bioactive analogs, we used liquid chromatogram tandem mass spectrometry (LC-MS/MS) to analyze the mass spectrometric characteristics of the isolated compounds as well as the crude extracts. As a result, three other analogs were detected, and their structures were deduced according to the similar fragmentation patterns. This is the first systematic report on the mass spectrometric characteristics of prenylated indole derivatives.

  18. Spectrometric properties of crystals for low-energy x-ray diagnostics

    International Nuclear Information System (INIS)

    Barrus, D.m.; Blake, R.L.; Felthauser, H.; Fenimore, E.E.

    1981-01-01

    Quantitative diagnostics of fusion and astrophysical plasmas require knowledge of crystal spectrometric properties. To provide more reliable and versatile diagnostics of plasma conditions, increasingly accurate knowledge of crystal spectrometric properties is becoming necessary. A summary is presented of the following accurately measured parameters for the crystals KAP, RbAP, TlAP, NH 4 AP, NaAP, ADP, and EDDT: the interplanar spacing of atoms; the angle correction for normal and anomalous dispersion that is required for application of the Bragg formula; the thermal expansion coefficient near room temperature for commonly used planes; and the integrated coefficient of reflection

  19. The difference between the potentiometric surfaces of the Upper Patapsco aquifer in southern Maryland, September 1990 and September 2009

    Science.gov (United States)

    Curtin, Stephen E.; Andreasen, David C.; Staley, Andrew W.

    2010-01-01

    This report presents a map showing the change in the potentiometric surface of the upper Patapsco aquifer in the Patapsco Formation of Early Cretaceous age in Southern Maryland between September 1990 and September 2009. The map, based on water level differences obtained from 33 wells, shows that during the 19-year period, the change in the potentiometric surface ranged from zero at the edge of the outcrop area in northern Anne Arundel County to a decline of 20 feet at Broad Creek, 16 feet near Arnold, 32 feet at Waldorf, 37 feet at the Chalk Point power plant, and 43 feet at Lexington Park. The map also shows well yield in gallons per day for 2008 at wells or well fields.

  20. Difference between the potentiometric surfaces of the Lower Patapsco aquifer in southern Maryland, September 1990 and September 2009

    Science.gov (United States)

    Curtin, Stephen E.; Andreasen, David C.; Staley, Andrew W.

    2010-01-01

    This report presents a map showing the change in the potentiometric surface of the lower Patapsco aquifer in the Patapsco Formation of Early Cretaceous age in Southern Maryland between September 1990 and September 2009. The map, based on water level differences obtained from 45 wells, shows that the change of the potentiometric surface during the 19-year period ranged from increases of 25 feet at Indian Head and 4 feet near the outcrop area in Glen Burnie, to declines of 35 feet at Arnold, 56 feet at Severndale, 28 feet at Crofton Meadows, 73 feet at Waldorf, 79 feet near La Plata, 35 feet at the Morgantown power plant, and 32 feet at Swan Point. The map also shows well yield in gallons per day for 2008 at wells or well fields.

  1. The difference between the potentiometric surfaces of the lower Patapsco aquifer in southern Maryland, September 1990 and September 2007

    Science.gov (United States)

    Curtin, Stephen E.; Andreasen, David C.; Staley, Andrew W.

    2009-01-01

    This report presents a map showing the change in the potentiometric surface of the lower Patapsco aquifer in the Patapsco Formation of Early Cretaceous age in Southern Maryland for September 1990 and September 2007. The map, based on water-level measurements in 45 wells, shows that the change of the potentiometric surface during the 17-year period ranged from increases of 19 feet at Indian Head and 6 feet near the outcrop area in Glen Burnie, to declines of 41 feet at Arnold, 45 feet at Severndale, 68 feet at Crofton Meadows, 77 feet at Waldorf, 76 feet at La Plata, 28 feet at the Morgantown power plant, and 35 feet at the Swan Point subdivision south of Morgantown.

  2. Insights into the potentiometric response behaviour vs. Li+ of LiFePO4 thin films in aqueous medium

    International Nuclear Information System (INIS)

    Sauvage, F.; Tarascon, J.-M.; Baudrin, E.

    2008-01-01

    The potentiometric response of PLD-made LiFePO 4 thin films versus Li + ions in aqueous solutions has been investigated, and a sensitivity of 54 mV dec -1 has been observed in a Li + concentration range of 1-10 -4 M. Physical and electrochemical measurements of electrodes aged in aqueous medium show a slight surface oxidation with formation of heterosite-FePO 4 that we show to be responsible for the stable potential response measured. Cyclic voltamperometry measurements operated in different Li + concentration clearly highlight the key relation between the material lithium ion insertion/de-insertion capability and its potentiometric sensing response implying a faradaic-governed sensing mechanism. Based on such a finding, selection criteria (enlisting among others the potential of the redox couple, the nature of the insertion process) are herein underlined in the search for new sensitive materials

  3. Determination of dissociation constants for coordination compounds of Cr(III) and Co(III) using potentiometric and spectrophotometric methods

    Energy Technology Data Exchange (ETDEWEB)

    Chylewska, A.; Jacewicz, D.; Zarzeczanska, D. [Department of Chemistry, University of Gdansk, Sobieskiego 18/19, 80-952 Gdansk (Poland); Chmurzynski, L. [Department of Chemistry, University of Gdansk, Sobieskiego 18/19, 80-952 Gdansk (Poland)], E-mail: lech@chem.univ.gda.pl

    2008-08-15

    The acid-base properties of analogous complex ions of chromium(III) and cobalt(III) in aqueous solution have been studied. The equilibrium constants for all metal complexes were determined by using potentiometric and spectrophotometric titration methods. First, dissociation constants for the studied complexes of Cr(III) and Co(III) were determined by means of the potentiometric titration method and using the STOICHIO computer programme. Then, pH-spectrophotometric titrations were performed and the OriginPro 7.5 computer programme was used to calculate the same constants. The measurements using both methods were carried out under the same conditions of temperature, T = 298.15 K, and over the same pH range 2.00-10.00, respectively. It turned out that the two methods used enabled us to obtain acidity constants in very good agreement.

  4. Determination of dissociation constants for coordination compounds of Cr(III) and Co(III) using potentiometric and spectrophotometric methods

    International Nuclear Information System (INIS)

    Chylewska, A.; Jacewicz, D.; Zarzeczanska, D.; Chmurzynski, L.

    2008-01-01

    The acid-base properties of analogous complex ions of chromium(III) and cobalt(III) in aqueous solution have been studied. The equilibrium constants for all metal complexes were determined by using potentiometric and spectrophotometric titration methods. First, dissociation constants for the studied complexes of Cr(III) and Co(III) were determined by means of the potentiometric titration method and using the STOICHIO computer programme. Then, pH-spectrophotometric titrations were performed and the OriginPro 7.5 computer programme was used to calculate the same constants. The measurements using both methods were carried out under the same conditions of temperature, T = 298.15 K, and over the same pH range 2.00-10.00, respectively. It turned out that the two methods used enabled us to obtain acidity constants in very good agreement

  5. Stuides on a Pb2+-selective electrode with a macrocyclic liquid membrane. Potentiometric determination of Pb2+ ions

    Directory of Open Access Journals (Sweden)

    MARIAN ISVORANU

    2006-12-01

    Full Text Available This paper presents experimental and theoretical data regarding the design, characterization and analytical applications of a non-expensive, liquid-membrane ion-selective electrode for Pb2+ ions. The membrane is a solution of the active complex formed by Pb2+ ions with dibenzo-18-crown-6-ionophore (DB-[18]-C-6 extracted in propylene carbonate (PC. The sucessful application of the developed electrode for the determination of Pb2+ ions in aqueos solution samples by direct potentiometry and potentiometric titration is presented. For the presented analytical results, there are insignificant systematic errors between the direct potentiometric method with the developed ion-selective electrode and atomic absorption spectrometry.

  6. Comparison of HPLC, UV spectrophotometry and potentiometric titration methods for the determination of lumefantrine in pharmaceutical products.

    Science.gov (United States)

    da Costa César, Isabela; Nogueira, Fernando Henrique Andrade; Pianetti, Gérson Antônio

    2008-09-10

    This paper describes the development and evaluation of a HPLC, UV spectrophotometry and potentiometric titration methods to quantify lumefantrine in raw materials and tablets. HPLC analyses were carried out using a Symmetry C(18) column and a mobile phase composed of methanol and 0.05% trifluoroacetic acid (80:20), with a flow rate of 1.0ml/min and UV detection at 335nm. For the spectrophotometric analyses, methanol was used as solvent and the wavelength of 335nm was selected for the detection. Non-aqueous titration of lumefantrine was carried out using perchloric acid as titrant and glacial acetic acid/acetic anhydride as solvent. The end point was potentiometrically determined. The three evaluated methods showed to be adequate to quantify lumefantrine in raw materials, while HPLC and UV methods presented the most reliable results for the analyses of tablets.

  7. Influence of morphology and topography on potentiometric response of magnesium and calcium sensitive PEDOT films doped with adenosine triphosphate (ATP)

    International Nuclear Information System (INIS)

    Paczosa-Bator, B.; Peltonen, J.; Bobacka, J.; Lewenstam, A.

    2006-01-01

    Poly(3,4-ethylenedioxythiophene) (PEDOT) films doped with adenosine triphosphate (ATP) are used to study the biologically relevant competitive magnesium and calcium ion-exchange at ATP membrane sites. It is shown, by atomic force microscopy (AFM) and scanning electron microscopy (SEM), that the surface topography and morphology of the PEDOT-ATP films determines the quality of their potentiometric response. More smooth and less rough films result in better potentiometric characteristics, particularly in a faster response. The topography/morphology of the PEDOT-ATP films is influenced by conditions during electrodeposition (electrochemical method of deposition, pH, concentration of electrolytes) and post-deposition soaking (including net-time of soaking), as evidenced by X-ray photoelectron spectroscopy (XPS) and energy dispersive analysis of X-rays (EDAX)

  8. Microparticles of Ag/Ag_2S type core-shell as potentiometric sensor for detection of cyanide

    International Nuclear Information System (INIS)

    Olazo Quispe, Renzo; La Rosa-Toro Gomez, Adolfo

    2014-01-01

    The synthesis of silver microparticles with surface film of silver sulfide mixed with graphite powder has yielded an electrochemical sensor capable of detecting cyanide with good sensitivity. Silver and silver sulfide microparticles was characterized by cyclic voltammetry (CV), X-ray diffraction (XRD), X-ray Fluorescence (XRF), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometry X-ray (EDX). Potentiometric assays were performed to determine the selectivity coefficient of the sensor. (author)

  9. Conductimetric and Potentiometric Titration of Some Hydroxylated Cinnamic Acids with Tetrabutylammonium Hydroxide in Non-Aqueous Media

    OpenAIRE

    AKTAŞ, A. Hakan; YAŞAR, Gülsüm; ALSANCAK, Güleren ÖZKAN

    2001-01-01

    In this study, four hydroxycinnamic acids, namely 3,4-dihydroxycinnamic acid, 4-hydroxycinnamic acid, 4-hydroxy --3- methoxycinnamic acid and 4-hydroxy-3,5-dimethoxycinnamic acid, were titrated conductimetrically and potentiometrically using triethylamine and tetrabutylammonium hydroxide in acetonitrile, 2-propanol, and pyridine solvents under a nitrogen atmosphere at 25 oC. In conductimetric titration with tetrabutylammonium hydroxide all of the compounds exhibited conventional s...

  10. A nonaqueous potentiometric titration study of the dissociation of t-butyl methacrylate-methacrylic acid copolymers.

    Science.gov (United States)

    Nakatani, Kiyoharu; Yamashita, Jun; Sekine, Tomomi; Toriumi, Minoru; Itani, Toshiro

    2003-05-01

    The dissociation of t-butyl methacrylate-methacrylic acid copolymers in dimethyl sulfoxide was analyzed by a nonaqueous potentiometric titration technique. The negative logarithm of the dissociation constant of the monomer unit of a methacrylic acid (MAA) monotonously increased with the increasing degree of dissociation corresponding to the titrant/MAA amount ratio, and was highly influenced by the copolymerization ratio. The results are discussed in terms of the suppression of the dissociation of MAA by a neighboring charged methacrylate anion unit.

  11. Potentiometric study of samarium oxides formation from its chloride in a molten eutectic mixture of sodium and cesium chlorides

    International Nuclear Information System (INIS)

    Smolenskij, V.V.; Bove, A.L.; Del'mukhamedov, R.D.; Borodina, N.P.; Gavrilov, A.G.

    1997-01-01

    Interaction of trivalent samarium cations with oxide-ions in NaCl-2CsCl melt at 973 K has been studied by potentiometric method using electrochemical cell with two platinum-oxygen electrodes with a solid electrolyte membrane. The mechanism of the interaction and composition of the reaction products, depending on the medium oxyacidity, have been considered. Certain thermodynamic characteristics of the process have been calculated

  12. The nature of single-ion activity coefficients calculated from potentiometric measurements on cells with liquid junctions

    Energy Technology Data Exchange (ETDEWEB)

    Zarubin, Dmitri P., E-mail: dmitri.zarubin@mtu-net.ru [Department of Physical and Collod Chemistry, Moscow State University of Technology and Management, 73 Zemlyanoi Val, Moscow 109803 (Russian Federation)

    2011-08-15

    Highlights: > Problem of ionic activity coefficients, determined by potentiometry, is reconsidered. > They are found to be functions of mean activity coefficients and transport numbers of ions. > The finding is verified by calculations and comparing the results with reported data. > Calculations are performed for systems with single electrolytes and binary mixtures. - Abstract: Potentiometric measurements on cells with liquid junctions are sometimes used for calculations of single-ion activity coefficients in electrolyte solutions, the incidence of this being increased recently. As surmised by Guggenheim in the 1930s, such coefficients (of ions i), {gamma}{sub i}, are actually complicated functions of mean ionic activity coefficients, {gamma}{sub {+-}}, and transport numbers of ions, t{sub i}. In the present paper specific functions {gamma}{sub i}({gamma}{sub {+-}}, t{sub i}) are derived for a number of cell types with an arbitrary mixture of strong electrolytes in a one-component solvent in the liquid-junction system. The cell types include cells with (i) identical electrodes, (ii) dissimilar electrodes reversible to the same ions, (iii) dissimilar electrodes reversible to ions of opposite charge signs, (iv) dissimilar electrodes reversible to different ions of the same charge sign, and (v) identical reference electrodes and an ion-selective membrane permeable to ions of only one type. Pairs of functions for oppositely charged ions are found to be consistent with the mean ionic activity coefficients as would be expected for pairs of the proper {gamma}{sub i} quantities by definition of {gamma}{sub {+-}}. The functions are tested numerically on some of the reported {gamma}{sub i} datasets that are the more tractable. A generally good agreement is found with data reported for cells with single electrolytes HCl and KCl in solutions, and with binary mixtures in the liquid-junction systems of KCl from the reference solutions and NaCl and HCl from the test solutions. It

  13. A Double Slow Neutron Spectrometer; Spectrometre double pour neutrons lents; Dvojnoj spektrometr medlennykh nejtronov; Espectrometro doble para neutrones lentos

    Energy Technology Data Exchange (ETDEWEB)

    Bondarenko, I I; Liforov, V G; Nikolaev, M N; Orlov, V V; Parfenov, V A; Semenov, V A; Smirnov, V I; Turchin, V F [Fehi, Moscow, SSSR (Russian Federation)

    1963-01-15

    The neutron spectrometer described in the paper is intended for measurements of the angular and energy distribution of monochromatic slow neutrons, inelasticaily scattered by liquid and solid bodies. Experiments of this type permit detailed information to be obtained concerning the dynamics of the atoms in various aggregate states of a substance. The spectromeeter is based on the time-of-flight method. The pulse source of neutrons is the IBR (1) reactor. A mechanical interrupter, rotating synchronously with the disc of the IBR and having a prescribed phase shift, serves as the monochromator. A special phasing system ensures a phasee stability better than 0.5{sup o}. The neutrons scattered by the sample are recorded by a scintillation detector set at a given angle to the neutron beam. The resolving power of the spectrometer is - 15 {mu}s/m. The paper gives a detailed description of the construction of the spectroscope and its characteristics. (author) [French] Le spectrometre neutronique decrit dans le memoire est destine a mesurer la distribution en energie, la distribution angulaire et la diffusion inelastique des neutrons lents monochromatiques dans des liquides et des solides. Les experiences de ce genre permettent d'obtenir des renseignements detailles sur la dynamique des atomes dans de divers etats de la matiere. Le spectrometre est fonde sur la mesure du temps de vol. Comme source puisee de neutrons on a utilise le reacteur IBR-1. Le systeme monochromateur etait constitue par un interrupteur mecanique en rotation synchronisee avec celle du disque du reacteur IBR, avec un dephasage determine. Un dispositif special de dephasage assure la stabilite de la phase a 0,5{sup o} pres. La diffusion des neutrons par l'echantillon est enregistree a l'aide d'un detecteur a scintillations dispose sous un angle determine par rapport au faisceau de neutrons. Le pouvoir de resolution du spectrometre est d'environ 15 {mu}s/m. Les auteurs decrivent en detail la construction du

  14. Mass spectrometric analysis of small negative ions (e/m < 100) produced by Trichel pulse negative corona discharge fed by ozonised air

    OpenAIRE

    Skalny, J.D.; Horvath, G.; Mason, N.

    2007-01-01

    Mass spectrometric analysis of small negative ions (e/m < 100) produced by DC negative corona discharge in ozonised wet air both in flow and flow-stopped regimes was conducted at pressure of 30 kPa. The point-to-plain electrode system has been used. The yield of individual ions is strongly affected by trace concentrations of ozone in both regimes. Ozone concentration greater than 25 ppm is sufficient to completely suppress the appearance of O2- and a NO2- ion as well as theirs clusters in the...

  15. Retrospective detection of exposure to organophosphorus anti-cholinesterases: Mass spectrometric analysis of phosphylated human butyrylcholinesterase

    NARCIS (Netherlands)

    Fidder, A.; Hulst, A.G.; Noort, D.; Ruiter, R. de; Schans, M.J. van der; Benschop, H.P.; Langenberg, J.P.

    2002-01-01

    In this paper a novel and general procedure is presented for detection of organophosphate-inhibited human butyrylcholinesterase (HuBuChE), which is based on electrospray tandem mass spectrometric analysis of phosphylated nonapeptides obtained after pepsin digestion of the enzyme. The utility of this

  16. Radiochemical separation and alpha-spectrometric determination of Americium in different matrixes

    International Nuclear Information System (INIS)

    Radenkovic, M.; Joksic, J.; Paligoric, D.

    2009-01-01

    A method of separation and alpha-spectrometric determination of americium, developed in VINCA Institute of Nuclear Sciences is described in the paper. The procedure is convenient to be used for 241 Am determination in environmental matrixes as well as samples of human origin if a very small concentrations are expected, using 243 Am as a tracer for radiochemical yield recovery. (author) [sr

  17. Structure elucidation of metabolite x17299 by interpretation of mass spectrometric data.

    Science.gov (United States)

    Zhang, Qibo; Ford, Lisa A; Evans, Anne M; Toal, Douglas R

    2017-01-01

    A major bottleneck in metabolomic studies is metabolite identification from accurate mass spectrometric data. Metabolite x17299 was identified in plasma as an unknown in a metabolomic study using a compound-centric approach where the associated ion features of the compound were used to determine the true molecular mass. The aim of this work is to elucidate the chemical structure of x17299, a new compound by de novo interpretation of mass spectrometric data. An Orbitrap Elite mass spectrometer was used for acquisition of mass spectra up to MS 4 at high resolution. Synthetic standards of N,N,N -trimethyl-l-alanyl-l-proline betaine (l,l-TMAP), a diastereomer, and an enantiomer were chemically prepared. The planar structure of x17299 was successfully proposed by de novo mechanistic interpretation of mass spectrometric data without any laborious purification and nuclear magnetic resonance spectroscopic analysis. The proposed structure was verified by deuterium exchanged mass spectrometric analysis and confirmed by comparison to a synthetic standard. Relative configuration of x17299 was determined by direct chromatographic comparison to a pair of synthetic diastereomers. Absolute configuration was assigned after derivatization of x17299 with a chiral auxiliary group followed by its chromatographic comparison to a pair of synthetic standards. The chemical structure of metabolite x17299 was determined to be l,l-TMAP.

  18. The AS-76 interlaboratory experiment on the alpha spectrometric determination of Pu-238. Pt. 1

    International Nuclear Information System (INIS)

    Beyrich, W.; Spannagel, G.

    1979-12-01

    In cooperation with 26 laboratories of 11 countries or international organizations, the Safeguards Project of the Karlsruhe Nuclear Research Center carried out the interlaboratory program AS-76. It focused on the alpha-spectrometric determination of the Pu-238 isotope. The performance of the program as well as the results obtained are described. (orig.) 891 HP/orig. 892 MKO [de

  19. Mass spectrometric identification of isocyanate-induced modifications of keratins in human skin

    NARCIS (Netherlands)

    Hulst, A.G.; Verstappen, D.R.W.; Riet-van Oeveren, D. van der; Vermeulen, N.P.E.; Noort, D.

    2015-01-01

    In the current paper we show that exposure of human callus to isocyanates leads to covalent modifications within keratin proteins. Mass spectrometric analyses of pronase digests of keratin isolated from exposed callus show that both mono- and di-adducts (for di-isocyanates) are predominantly formed

  20. Preparation, characterization and application of urease nanoparticles for construction of an improved potentiometric urea biosensor.

    Science.gov (United States)

    Jakhar, Seema; Pundir, C S

    2018-02-15

    The nanoparticles (NPs) aggregates of commercial urease from jack beans (Canavalia ensiformis) were prepared by desolvation and glutaraldehyde crosslinking and functionalized by cysteamine dihydrochloride. These enzyme nanoparticles (ENPs) were characterized by transmission electron microscopy (TEM), UV and Fourier transform infrared (FTIR) spectroscopy. The TEM images of urease NPs showed their size in the range, 18-100nm with an average of 51.2nm. The ENPs were more active and stable with a longer shelf life than native enzyme molecules. The ENPs were immobilized onto chitosan (CHIT) activated nitrocellulose (NC) membrane via glutaraldehyde coupling with 32.22% retention of initial activity of free ureaseNPs with a conjugation yield of 1.63mg/cm 2 . This NC membrane was mounted at the lower/sensitive end of the ammonium ion selective electrode (AISE) with O-ring and then electrode was connected to a digital pH meter to construct a potentiometric urea biosensor. The biosensor exhibited optimum response within 10s at pH 5.5and 40°C. The biosensor was employed for measurement of potentiometric determination of urea in sera of apparently healthy and persons suffering from kidney disorders. The biosensor displayed a low detection limit of 1µM/L with a wide working range of 2-80µM/L (0.002-0.08mM) and sensitivity of 23mV/decade. The analytical recovery of added urea in serum was 106.33%. The within and between-batch coefficient of variations (CVs) of present biosensor were 0.18% and 0.32% respectively. There was a good correlation (r = 0.99) between sera urea values obtained by reference method (Enzymic colorimetric kit method) and the present biosensor. The biosensor had negligible interference from Na + ,K + ,NH +4 and Ca 2+ but Mg 2+ ,Cu 2+ and ascorbic acid but had slight interference, which was overcome by specific ion selective electrode. The ENPs bound NC membrane was used maximally 8-9 times per day over a period of 180 days, when stored in 0.01M sodium

  1. Perception of olive oils sensory defects using a potentiometric taste device.

    Science.gov (United States)

    Veloso, Ana C A; Silva, Lucas M; Rodrigues, Nuno; Rebello, Ligia P G; Dias, Luís G; Pereira, José A; Peres, António M

    2018-01-01

    The capability of perceiving olive oils sensory defects and intensities plays a key role on olive oils quality grade classification since olive oils can only be classified as extra-virgin if no defect can be perceived by a human trained sensory panel. Otherwise, olive oils may be classified as virgin or lampante depending on the median intensity of the defect predominantly perceived and on the physicochemical levels. However, sensory analysis is time-consuming and requires an official sensory panel, which can only evaluate a low number of samples per day. In this work, the potential use of an electronic tongue as a taste sensor device to identify the defect predominantly perceived in olive oils was evaluated. The potentiometric profiles recorded showed that intra- and inter-day signal drifts could be neglected (i.e., relative standard deviations lower than 25%), being not statistically significant the effect of the analysis day on the overall recorded E-tongue sensor fingerprints (P-value = 0.5715, for multivariate analysis of variance using Pillai's trace test), which significantly differ according to the olive oils' sensory defect (P-value = 0.0084, for multivariate analysis of variance using Pillai's trace test). Thus, a linear discriminant model based on 19 potentiometric signal sensors, selected by the simulated annealing algorithm, could be established to correctly predict the olive oil main sensory defect (fusty, rancid, wet-wood or winey-vinegary) with average sensitivity of 75 ± 3% and specificity of 73 ± 4% (repeated K-fold cross-validation variant: 4 folds×10 repeats). Similarly, a linear discriminant model, based on 24 selected sensors, correctly classified 92 ± 3% of the olive oils as virgin or lampante, being an average specificity of 93 ± 3% achieved. The overall satisfactory predictive performances strengthen the feasibility of the developed taste sensor device as a complementary methodology for olive oils' defects analysis and subsequent

  2. Ionophore-Based Potentiometric Sensors for the Flow-Injection Determination of Promethazine Hydrochloride in Pharmaceutical Formulations and Human Urine

    Directory of Open Access Journals (Sweden)

    Suad Mustafa Al-Araji

    2011-01-01

    Full Text Available Plasticised poly(vinyl chloride-based membranes containing the ionophores (α-, β- and γ-cyclodextrins (CD, dibenzo-18-crown-6 (DB18C6 and dibenzo-30-crown-10 (DB30C10 were evaluated for their potentiometric response towards promethazine (PM in a flow injection analysis (FIA set-up. Good responses were obtained when β- and γ-CDs, and DB30C10 were used. The performance characteristics were further improved when tetrakis(4-chlorophenyl borate (KTPB was added to the membrane. The sensor based on β-CD, bis(2-ethylhexyl adipate (BEHA and KTPB exhibited the best performance among the eighteen sensor compositions that were tested. The response was linear from 1 x 10−5 to 1 x 10−2 M, slope was 61.3 mV decade−1, the pH independent region ranged from 4.5 to 7.0, a limit of detection of 5.3 x 10−6 M was possible and a lifetime of more than a month was observed when used in the FIA system. Other plasticisers such as dioctyl phenylphosphonate and tributyl phosphate do not show significant improvements in the quality of the sensors. The promising sensors were further tested for the effects of foreign ions (Li+, Na+, K+, Mg2+, Ca2+, Co2+, Cu2+, Cr3+, Fe3+, glucose, fructose. FIA conditions (e.g., effects of flow rate, injection volume, pH of the carrier stream were also studied when the best sensor was used (based on β-CD. The sensor was applied to the determination of PM in four pharmaceutical preparations and human urine that were spiked with different levels of PM. Good agreement between the sensor and the manufacturer’s claimed values (for pharmaceutical preparations was obtained, while mean recoveries of 98.6% were obtained for spiked urine samples. The molecular recognition features of the sensors as revealed by molecular modelling were rationalised by the nature of the interactions and complexation energies between the host and guest molecules.

  3. A potentiometric biosensor for the detection of notch 3 using functionalized ZnO nanorods.

    Science.gov (United States)

    Ibupoto, Z H; Khun, K; Liu, X; Willander, M

    2014-09-01

    The notch signalling plays a vital and radical role for the activity of cellular proliferation, differentiation and apoptosis. In this study, for the first time a particular biosensor is developed for the detection of notch 3. ZnO nanorods were fabricated on the gold coated glass substrate by hydrothermal method and afterwards were decorated with the gold nanoparticles by electrodepositing technique. Scanning electron microscopy (SEM) has shown the perpendicular to the substrate growth pattern of ZnO nanorods. X-ray diffraction (XRD) studies showed the c-axis oriented growth direction with wurtzite crystal structure of ZnO nanorods. X-ray Photoelectron Spectroscopy (XPS) and energy dispersive X-ray (EDX) techniques have shown the presence of Zn, O and Au atoms in the prepared functional material. Furthermore, the anti-notch 3 was physically adsorbed on the gold nanoparticles functionalized ZnO nanorods. The developed potentiometric immunosensor has shown response to the wide range of notch 3 molecules. The detected range included 1.00 x 10(-5)-1.50 x 10(0 ) μg/mL with a sensitivity of 23.15 ± 0.31 mV/decade. The analytical parameters including reproducibility, stability, and selectivity were also investigated and the observed results indicate the acceptable performance of the notch 3 biosensor. Moreover, the proposed notch 3 biosensor exhibited a fast response time of 10 s.

  4. Model compounds of humic acid and oxovanadium cations. Potentiometric titration and EPR spectroscopy studies

    Directory of Open Access Journals (Sweden)

    Mercê Ana Lucia Ramalho

    1999-01-01

    Full Text Available The stability constants and the isotropic EPR parameters Ao (hyperfine splitting constant and g o (g value were obtained by potentiometric titrations and EPR spectroscopy, respectively, of 85%v/v aqueous solutions of model compounds of humic acids - salicylic acid (SALA - and both nitrohumic acids, a laboratory artifact - nitrosalicylic acids, 3-nitrosalicylic acid (3-NSA, 5-nitrosalicylic acid (5-NSA and 3,5-dinitrosalicylic acid (3,5-DNSA and oxovanadium cations. It was possible to record EPR spectra of those model compounds and the ion VO2+ (V(IV, and the stability constants were obtained from a solution of VO3+ (V(V, the values for the logarithms of the stability constants ranging from 12.77 ± 0.04 to 7.06 ± 0.05 for the species ML, and from 9.90 ±0.04 to 4.06 ± 0.05 for the species ML2 according to the decrease in the acidity of the carboxylic and the hydroxyl groups in the aromatic ring of the model compounds studied as the -NO2 substituents were added. Species distribution diagrams were also obtained for the equilibria studied. The EPR parameters showed that as the logarithm of the overall stability constants increase, g o values also increase, while Ao values show a tendency to decrease.

  5. Fe (III - Galactomannan Solid and Aqueous Complexes: Potentiometric, EPR Spectroscopy and Thermal Data

    Directory of Open Access Journals (Sweden)

    Mercê Ana L. R.

    2001-01-01

    Full Text Available Galactomannans can be employed in food industries to modify the final rheological properties of the products. Since they are not absorbed by the living organisms they can also be used in dietary foods. The equilibria involving the interactions of Fe(III and galactomannans and arabinogalactan of several leguminous plants were characterized by potentiometric titrations and EPR spectroscopy. The log of the equilibrium constants for the formation of ML species, where M is the metal ion and L is the monomeric unit of the biopolymers, were 15.4, 14.1 and 18.5, for the galactomannans of C. fastuosa, L. leucocephala and S. macranthera, respectively. Log K values for protonated species (MHL were 3.1, 3.3, and were not detected for the galactomannan of S. macranthera. The log K values for the formation of ML2 were 14.1, 13.3 and 15.2, respectively. Early formation of insoluble products in the equilibrium with arabinogalactan and Fe(III prevented acquisition of reliable data. The solid complexes assays showed a great dipolar interaction between two Fe(III ions in the inner structure of the biopolymer which increased as the degree of substitution of the galactomannan decreased, and also showed the resulting thermal stability. The complexes impart a new possibility of providing essential metal ions in dietary foods since decomplexation of the complexes can occur at different pH values existing in the human body.

  6. Indicator electrodes from d-elements for application in different types of potentiometric analytical methods

    Directory of Open Access Journals (Sweden)

    Z. Kunasheva

    2012-05-01

    Full Text Available The article covers the use of metal electrodes from titanium, tungsten, molybdenum as indicator electrodes at potentiometric method of analysis. The condition of measuring operation in dependence on pH, ionic strength of solutions is described in the article. Electrode potential of testing electrodes are measured in the interval of concentration of salts from 0,1∙10-1 mole/l till 0,1∙10-6 mole/l. The results of testing of electrical-analytical description of metal electrodes made of d-elements, in particular, titanium, tungsten, molybdenum in solutions of cations of some metals and anions were mentioned. As ions of metal cations Cu2+, Cd2+, Zn2+, Pb2+ and anions Cl-, I-, F- were chosen.It is identified that titanic electrode has different response to ions of copper (II, zinc and cadmium. However, dependence of electrode potential on concentration of ions of metal is rectilinear, that is vequired of indicator electrodes in the direct potential metrics.  

  7. Potentiometric determination of acid dissociation constants (pKa) for human and veterinary antibiotics.

    Science.gov (United States)

    Qiang, Zhimin; Adams, Craig

    2004-07-01

    This work determined the acid dissociation constants (pKa) of 26 common human and veterinary antibiotics by potentiometric titration. Selected antibiotics consisted of sulfonamides, macrolides, tetracyclines, fluoroquinolones, and other miscellaneous antibiotics. After validation of analysis methods using phosphoric acid as a model compound, a second-derivative (delta2pH/deltaV2) method was primarily applied to determining pKa's from titration curves for most antibiotics due to its convenience and accuracy. For tetracyclines, however, a least-square non-linear regression method was developed to determine their pKa's because the second-derivative method cannot well distinguish the pKa,2 and pKa,3 of tetracyclines. Results indicate that the pKa values are approximately 2 and 5-7.5 for sulfonamides; 7.5-9 for macrolides; 3-4, 7-8 and 9-10 for tetracyclines; 3-4, 6, 7.5-9 and 10-11 for fluoroquinolones; while compound-specific for other miscellaneous antibiotics. The moieties corresponding to specific pKa's were identified based on chemical structures of antibiotics. In addition, the pKa's available in literature determined by various techniques are compiled in comparison with the values of this work. These results are expected to essentially facilitate the research on occurrence, fate and effects, analysis methods development, and control of antibiotics in various treatment operations.

  8. Coulometric-potentiometric determination of autoprotolysis constant and relative acidity scale of water

    Directory of Open Access Journals (Sweden)

    Džudović Radmila M.

    2010-01-01

    Full Text Available The autoprotolysis constant and relative acidity scale of water were determined by applying the coulometric-potentiometric method and a hydrogen/palladium (H2/Pd generator anode. In the described procedure for the evaluation of autoprotolysis constant, a strong base generated coulometrically at the platinum cathode in situ in the electrolytic cell, in presence of sodium perchlorate as the supporting electrolyte, is titrated with hydrogen ions obtained by the anodic oxidation of hydrogen dissolved in palladium electrode. The titration was carried out with a glass-SCE electrode pair at 25.0±0.1°C. The value obtained pKw = 13.91 ± 0.06 is in agreement with literature data. The range of acidity scale of water is determined from the difference between the halfneutralization potentials of electrogenerated perchloric acid and that of sodium hydroxide in a sodium perchlorate medium. The halfneutralization potentials were measured using both a glass-SCE and a (H2/Pdind-SCE electrode pairs. A wider range of relative acidity scale of water was obtained with the glass-SCE electrode pair.

  9. Manganese(III Porphyrin-based Potentiometric Sensors for Diclofenac Assay in Pharmaceutical Preparations

    Directory of Open Access Journals (Sweden)

    Eugenia Fagadar-Cosma

    2010-09-01

    Full Text Available Two manganese(III porphyrins: manganese(III tetraphenylporphyrin chloride and manganese(III-tetrakis(3-hydroxyphenylporphyrin chloride were tested as ionophores for the construction of new diclofenac−selective electrodes. The electroactive material was incorporated either in PVC or a sol−gel matrix. The effect of different plasticizers and additives (anionic and cationic on the potentiometric response was studied. The best results were obtained for the PVC membrane plasticized with dioctylphtalate and having sodium tetraphenylborate as a lipophilic anionic additive incorporated. The sensor response was linear in the concentration range 3 × 10−6 – 1 × 10−2 M with a slope of −59.7 mV/dec diclofenac, a detection limit of 1.5 × 10−6 M and very good selectivity coefficients. It was used for the determination of diclofenac in pharmaceutical preparations, by direct potentiometry. The results were compared with those obtained by the HPLC reference method and a good agreement was found between the two methods.

  10. New Potentiometric Wireless Chloride Sensors Provide High Resolution Information on Chemical Transport Processes in Streams

    Directory of Open Access Journals (Sweden)

    Keith Smettem

    2017-07-01

    Full Text Available Quantifying the travel times, pathways, and dispersion of solutes moving through stream environments is critical for understanding the biogeochemical cycling processes that control ecosystem functioning. Validation of stream solute transport and exchange process models requires data obtained from in-stream measurement of chemical concentration changes through time. This can be expensive and time consuming, leading to a need for cheap distributed sensor arrays that respond instantly and record chemical transport at points of interest on timescales of seconds. To meet this need we apply new, low-cost (in the order of a euro per sensor potentiometric chloride sensors used in a distributed array to obtain data with high spatial and temporal resolution. The application here is to monitoring in-stream hydrodynamic transport and dispersive mixing of an injected chemical, in this case NaCl. We present data obtained from the distributed sensor array under baseflow conditions for stream reaches in Luxembourg and Western Australia. The reaches were selected to provide a range of increasingly complex in-channel flow patterns. Mid-channel sensor results are comparable to data obtained from more expensive electrical conductivity meters, but simultaneous acquisition of tracer data at several positions across the channel allows far greater spatial resolution of hydrodynamic mixing processes and identification of chemical ‘dead zones’ in the study reaches.

  11. Highly Selective and Sensitized Spectrophotometric Determination of Iron (3) Following Potentiometric Study

    International Nuclear Information System (INIS)

    Shokrollahi, A.; Ghaedi, M.; Rajabi, H.R.

    2007-01-01

    A simple, selective and sensitized spectrophotometric method for determination of trace amounts of Fe 3+ ion in tap and waste water solutions has been described. The spectrophotometric determination of Fe 3+ ion using Ferron in the presence of N,N-Dodecy trimethylammonium bromide (DTAB) has been carried out. The Beer's law is obeyed over the concentration range of 0.05-2.6 μg mL -1 of Fe 3+ ion with the relative standard deviation (RSD %) 3 L mol -1 cm -1 . Potentiometric pH titration has been used for prediction of protonation constants of ferron, and evaluating its stoichiometry and respective stability constant with Fe 3+ ion. As it is obvious the most likely species of ferron alone and its complexes are LH (log=7.64), LH 2 (logK=10.52), LH 3 (logK=11.74) and ML 2 (logβ= 23.68), ML 3 (logβ23.68), ML 3 H (logβ= 23.68), ML 3 H 2 (logβ= 23.68) and ML(OH) 2 (logβ=23.68) respectively

  12. Potentiometric pH-sensor based on electro polymerized poly (ο-phenylenediamine)

    International Nuclear Information System (INIS)

    Binag, Christina A.; Tongol, Bernard John V.

    1998-01-01

    A novel potentiometric pH-sensor device was fabricated using galvanostatic electrochemical polymerization of poly (ο-phenylenediamine) (PoPD) onto a Pt wire from a suitable buffer solution containing the doubly crystallized ο-phenylenediamine and the dopant bovine serum albumin (BSA). Electrochemical polymerization parameters of the sensor were optimized against Ag/AgCl electrode using electrode using buffer solutions of pH 3 to 10. The polymer-coated pH-sensor exhibited a high sensitivity with nearly Nermstian response and a slope of -47.5 mV/pH, a good linearity (r=-0.991), a reasonable response time (8 min. at pH 3-10), a favorable repeatability at three (3) replicate measurements (RSD=6% at pH 3-8), and a very high reproductibility (RSD <3%) at 11 replicate and alternate measurements of pH3 and 10 for a period of <2 h. This yellow-brown PoPD polymer coated Pt wire is a promising pH transducer for the analysis of pH changes in biological reactions acting as biosensor. (Author)

  13. A Potentiometric Formaldehyde Biosensor Based on Immobilization of Alcohol Oxidase on Acryloxysuccinimide-modified Acrylic Microspheres

    Directory of Open Access Journals (Sweden)

    Lee Yook Heng

    2010-11-01

    Full Text Available A new alcohol oxidase (AOX enzyme-based formaldehyde biosensor based on acrylic microspheres has been developed. Hydrophobic poly(n-butyl acrylate-N-acryloxy-succinimide [poly(nBA-NAS] microspheres, an enzyme immobilization matrix, was synthesized using photopolymerization in an emulsion form. AOX-poly(nBA-NAS microspheres were deposited on a pH transducer made from a layer of photocured and self-plasticized polyacrylate membrane with an entrapped pH ionophore coated on a Ag/AgCl screen printed electrode (SPE. Oxidation of formaldehyde by the immobilized AOX resulted in the production of protons, which can be determined via the pH transducer. Effects of buffer concentrations, pH and different amount of immobilization matrix towards the biosensor’s analytical performance were investigated. The formaldehyde biosensor exhibited a dynamic linear response range to formaldehyde from 0.3–316.2 mM and a sensitivity of 59.41 ± 0.66 mV/decade (R2 = 0.9776, n = 3. The lower detection limit of the biosensor was 0.3 mM, while reproducibility and repeatability were 3.16% RSD (relative standard deviation and 1.11% RSD, respectively (n = 3. The use of acrylic microspheres in the potentiometric formaldehyde biosensor improved the biosensor’s performance in terms of response time, linear response range and long term stability when compared with thick film immobilization methods.

  14. Single-cultivar extra virgin olive oil classification using a potentiometric electronic tongue.

    Science.gov (United States)

    Dias, Luís G; Fernandes, Andreia; Veloso, Ana C A; Machado, Adélio A S C; Pereira, José A; Peres, António M

    2014-10-01

    Label authentication of monovarietal extra virgin olive oils is of great importance. A novel approach based on a potentiometric electronic tongue is proposed to classify oils obtained from single olive cultivars (Portuguese cvs. Cobrançosa, Madural, Verdeal Transmontana; Spanish cvs. Arbequina, Hojiblanca, Picual). A meta-heuristic simulated annealing algorithm was applied to select the most informative sets of sensors to establish predictive linear discriminant models. Olive oils were correctly classified according to olive cultivar (sensitivities greater than 97%) and each Spanish olive oil was satisfactorily discriminated from the Portuguese ones with the exception of cv. Arbequina (sensitivities from 61% to 98%). Also, the discriminant ability was related to the polar compounds contents of olive oils and so, indirectly, with organoleptic properties like bitterness, astringency or pungency. Therefore the proposed E-tongue can be foreseen as a useful auxiliary tool for trained sensory panels for the classification of monovarietal extra virgin olive oils. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Ion-selective electrodes in potentiometric titrations; a new method for processing and evaluating titration data.

    Science.gov (United States)

    Granholm, Kim; Sokalski, Tomasz; Lewenstam, Andrzej; Ivaska, Ari

    2015-08-12

    A new method to convert the potential of an ion-selective electrode to concentration or activity in potentiometric titration is proposed. The advantage of this method is that the electrode standard potential and the slope of the calibration curve do not have to be known. Instead two activities on the titration curve have to be estimated e.g. the starting activity before the titration begins and the activity at the end of the titration in the presence of large excess of titrant. This new method is beneficial when the analyte is in a complexed matrix or in a harsh environment which affects the properties of the electrode and the traditional calibration procedure with standard solutions cannot be used. The new method was implemented both in a method of linearization based on the Grans's plot and in determination of the stability constant of a complex and the concentration of the complexing ligand in the sample. The new method gave accurate results when using titrations data from experiments with samples of known composition and with real industrial harsh black liquor sample. A complexometric titration model was also developed. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. End-point detection in potentiometric titration by continuous wavelet transform.

    Science.gov (United States)

    Jakubowska, Małgorzata; Baś, Bogusław; Kubiak, Władysław W

    2009-10-15

    The aim of this work was construction of the new wavelet function and verification that a continuous wavelet transform with a specially defined dedicated mother wavelet is a useful tool for precise detection of end-point in a potentiometric titration. The proposed algorithm does not require any initial information about the nature or the type of analyte and/or the shape of the titration curve. The signal imperfection, as well as random noise or spikes has no influence on the operation of the procedure. The optimization of the new algorithm was done using simulated curves and next experimental data were considered. In the case of well-shaped and noise-free titration data, the proposed method gives the same accuracy and precision as commonly used algorithms. But, in the case of noisy or badly shaped curves, the presented approach works good (relative error mainly below 2% and coefficients of variability below 5%) while traditional procedures fail. Therefore, the proposed algorithm may be useful in interpretation of the experimental data and also in automation of the typical titration analysis, specially in the case when random noise interfere with analytical signal.

  17. Analysis of the sorption properties of different soils using water vapour adsorption and potentiometric titration methods

    Science.gov (United States)

    Skic, Kamil; Boguta, Patrycja; Sokołowska, Zofia

    2016-07-01

    Parameters of specific surface area as well as surface charge were used to determine and compare sorption properties of soils with different physicochemical characteristics. The gravimetric method was used to obtain water vapour isotherms and then specific surface areas, whereas surface charge was estimated from potentiometric titration curves. The specific surface area varied from 12.55 to 132.69 m2 g-1 for Haplic Cambisol and Mollic Gleysol soil, respectively, and generally decreased with pH (R=0.835; α = 0.05) and when bulk density (R=-0.736; α = 0.05) as well as ash content (R=-0.751; α = 0.05) increased. In the case of surface charge, the values ranged from 63.00 to 844.67 μmol g-1 Haplic Fluvisol and Mollic Gleysol, respecively. Organic matter gave significant contributions to the specific surface area and cation exchange capacity due to the large surface area and numerous surface functional groups, containing adsorption sites for water vapour molecules and for ions. The values of cation exchange capacity and specific surface area correlated linearly at the level of R=0.985; α = 0.05.

  18. Use of marker ion and cationic surfactant plastic membrane electrode for potentiometric titration of cationic polyelectrolytes.

    Science.gov (United States)

    Masadome, Takashi; Imato, Toshihiko

    2003-07-04

    A plasticized poly (vinyl chloride) (PVC) membrane electrode sensitive to stearyltrimethylammonium (STA) ion is applied to the determination of cationic polyelectrolytes such as poly (diallyldimethylammonium chloride) (Cat-floc) by potentiometric titration, using a potassium poly (vinyl sulfate) (PVSK) solution as a titrant. The end-point of the titration is detected as the potential change of the plasticized PVC membrane electrode caused by decrease in the concentration of STA ion added to the sample solution as a marker ion due to the ion association reaction between the STA ion and PVSK. The effects of the concentration of STA ion, coexisting electrolytes in the sample solution and pH of the sample on the degree of the potential change at the end-point were examined. A linear relationship between the concentration of cationic polyelectrolyte and the end-point volume of the titrant exists in the concentration range from 2x10(-5) to 4x10(-4) N for Cat-floc, glycol chitosan, and methylglycol chitosan.

  19. Determination of Carbonyl Functional Groups in Bio-oils by Potentiometric Titration: The Faix Method.

    Science.gov (United States)

    Black, Stuart; Ferrell, Jack R

    2017-02-07

    Carbonyl compounds present in bio-oils are known to be responsible for bio-oil property changes upon storage and during upgrading. Specifically, carbonyls cause an increase in viscosity (often referred to as 'aging') during storage of bio-oils. As such, carbonyl content has previously been used as a method of tracking bio-oil aging and condensation reactions with less variability than viscosity measurements. Additionally, carbonyls are also responsible for coke formation in bio-oil upgrading processes. Given the importance of carbonyls in bio-oils, accurate analytical methods for their quantification are very important for the bio-oil community. Potentiometric titration methods based on carbonyl oximation have long been used for the determination of carbonyl content in pyrolysis bio-oils. Here, we present a modification of the traditional carbonyl oximation procedures that results in less reaction time, smaller sample size, higher precision, and more accurate carbonyl determinations. While traditional carbonyl oximation methods occur at room temperature, the Faix method presented here occurs at an elevated temperature of 80 °C.

  20. Estimation of uncertainty in pKa values determined by potentiometric titration.

    Science.gov (United States)

    Koort, Eve; Herodes, Koit; Pihl, Viljar; Leito, Ivo

    2004-06-01

    A procedure is presented for estimation of uncertainty in measurement of the pK(a) of a weak acid by potentiometric titration. The procedure is based on the ISO GUM. The core of the procedure is a mathematical model that involves 40 input parameters. A novel approach is used for taking into account the purity of the acid, the impurities are not treated as inert compounds only, their possible acidic dissociation is also taken into account. Application to an example of practical pK(a) determination is presented. Altogether 67 different sources of uncertainty are identified and quantified within the example. The relative importance of different uncertainty sources is discussed. The most important source of uncertainty (with the experimental set-up of the example) is the uncertainty of pH measurement followed by the accuracy of the burette and the uncertainty of weighing. The procedure gives uncertainty separately for each point of the titration curve. The uncertainty depends on the amount of titrant added, being lowest in the central part of the titration curve. The possibilities of reducing the uncertainty and interpreting the drift of the pK(a) values obtained from the same curve are discussed.

  1. Uncertainty evaluation in the chloroquine phosphate potentiometric titration: application of three different approaches.

    Science.gov (United States)

    Rodomonte, Andrea Luca; Montinaro, Annalisa; Bartolomei, Monica

    2006-09-11

    A measurement result cannot be properly interpreted if not accompanied by its uncertainty. Several methods to estimate uncertainty have been developed. From those methods three in particular were chosen in this work to estimate the uncertainty of the Eu. Ph. chloroquine phosphate assay, a potentiometric titration commonly used in medicinal control laboratories. The famous error-budget approach (also called bottom-up or step-by-step) described by the ISO Guide to the expression of Uncertainty in Measurement (GUM) was the first method chosen. It is based on the combination of uncertainty contributions that have to be directly derived from the measurement process. The second method employed was the Analytical Method Committee top-down which estimates uncertainty through reproducibility obtained during inter-laboratory studies. Data for its application were collected in a proficiency testing study carried out by over 50 laboratories throughout Europe. The last method chosen was the one proposed by Barwick and Ellison. It uses a combination of precision, trueness and ruggedness data to estimate uncertainty. These data were collected from a validation process specifically designed for uncertainty estimation. All the three approaches presented a distinctive set of advantages and drawbacks in their implementation. An expanded uncertainty of about 1% was assessed for the assay investigated.

  2. Development of potentiometric equipment for the identification of altered dry-cured hams: A preliminary study.

    Science.gov (United States)

    Girón, Joel; Gil-Sánchez, Luís; García-Breijo, Eduardo; Pagán, M Jesús; Barat, José M; Grau, Raúl

    2015-08-01

    Microbiological contamination in dry-cured ham can occur in the early stages of the process, a large number of microorganisms involved in spoilage can produce alterations in the product. These include non-common odours, which are detected at the end of the process by a procedure called "cala", consisting of a sharp instrument punctured in every ham; this is smelled by an expert taster, who classifies hams as good and altered hams. An electronic device would be suitable for this process given the large amount of hams. The present research aims to develop objective equipment based on the potentiometry technique that identifies altered hams. A probe was developed, containing silver, nickel and copper electrodes, and was employed to classify altered and unaltered hams prior to classification by a tester. The results shown lower Ag and higher Cu potential values for altered hams. The differences in potentiometric response reveal a classification model, although further studies are required to obtain a reliable classification model. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Development of novel potentiometric sensors for determination of tartrazine dye concentration in foodstuff products.

    Science.gov (United States)

    Abu Shawish, Hazem M; Ghalwa, Nasser Abu; Saadeh, Salman M; El Harazeen, Heba

    2013-05-01

    Tartrazine dye Na(3)TZ in foodstuff products was determined by a new modified carbon paste electrode, encoded sensor A, and a coated silver wire electrode, encoded sensor B, based on tartrazine TZ- cetryltrimethyl ammoniumbromide CTAB as a chemical modifier TZ-CTA. The electrodes exhibit the following characteristics listed respectively: a Nernstian slope of 17.9±0.5 and 19.4±0.2 mV/decade for tartrazine ion over a wide concentration range from 4.3×10(-7) to 1.0×10(-2) and 1.1×10(-7) to 1.0×10(-2) M. The lower detection limits: 3.2×10(-7) and 5.5×10(-8) M. Short response time (5-8 s) over the pH range 3.8-7.7 and 4.2-8.1. The proposed sensors display significantly high selectivity for TZ ion over a wide variety of sugars, some anions, common organic, inorganic compounds and additives. The developed electrodes were applied to the potentiometric determination of tartrazine ion in different kinds of foodstuffs: solid jelly (strawberry and custard) powder samples and soft drink (orange) samples with satisfactory results. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Graphene-based potentiometric biosensor for the immediate detection of living bacteria.

    Science.gov (United States)

    Hernández, Rafael; Vallés, Cristina; Benito, Ana M; Maser, Wolfgang K; Rius, F Xavier; Riu, Jordi

    2014-04-15

    In this communication we present a potentiometric aptasensor based on chemically modified graphene (transducer layer of the aptasensor) and aptamers (sensing layer). Graphene oxide (GO) and reduced graphene oxide (RGO) are the basis for the construction of two versions of the aptasensor for the detection of a challenging living organism such as Staphylococcus aureus. In these two versions, DNA aptamers are either covalently (in the GO case) or non-covalently (in the RGO case) attached to the transducer layer. In both cases we are able to selectively detect a single CFU/mL of S. aureus in an assay close to real time, although the noise level associated to the aptasensors made with RGO is lower than the ones made with GO. These new aptasensors, that show a high selectivity, are characterized by the simplicity of the technique and the materials used for their construction while offering ultra-low detection limits in very short time responses in the detection of microorganisms. © 2013 Published by Elsevier B.V.

  5. Solid-contact potentiometric sensors and multisensors based on polyaniline and thiacalixarene receptors for the analysis of some beverages and alcoholic drinks

    Science.gov (United States)

    Sorvin, Michail; Belyakova, Svetlana; Stoikov, Ivan; Shamagsumova, Rezeda; Evtugyn, Gennady

    2018-04-01

    Electronic tongue is a sensor array that aims to discriminate and analyze complex media like food and beverages on the base of chemometrics approaches for data mining and pattern recognition. In this review, the concept of electronic tongue comprising of solid-contact potentiometric sensors with polyaniline and thacalix[4]arene derivatives is described. The electrochemical reactions of polyaniline as a background of solid-contact sensors and the characteristics of thiacalixarenes and pillararenes as neutral ionophores are briefly considered. The electronic tongue systems described were successfully applied for assessment of fruit juices, green tea, beer and alcoholic drinks They were classified in accordance with the origination, brands and styles. Variation of the sensor response resulted from the reactions between Fe(III) ions added and sample components, i.e., antioxidants and complexing agents. The use of principal component analysis and discriminant analysis is shown for multisensor signal treatment and visualization. The discrimination conditions can be optimized by variation of the ionophores, Fe(III) concentration and sample dilution. The results obtained were compared with other electronic tongue systems reported for the same subjects.

  6. Potentiometric Surface of the Alluvial Aquifer and Hydrologic Conditions in the Juana Diaz area, Puerto Rico, June 29 - July 1, 2005

    Science.gov (United States)

    Rodriguez, Jose M.; Santigo-Rivera, Luis; Gómez-Gómez, Fernando

    2006-01-01

    A synoptic survey of the hydrologic conditions in the Juana Diaz area, Puerto Rico, was conducted between June 29 and July 1, 2005, to define the spatial distribution of the potentiometric surface of the alluvial aquifer. The study area encompasses 21 square miles of the more extensive South Coastal Plain Alluvial Aquifer system and is bounded along the north by foothills of the Cordillera Central mountain chain, to the south by the Caribbean Sea, the east by the Rio Descalabrado and to the west by the Rio Inabon. Ground water in the Juana Diaz area is in the Quaternary-age alluvial deposits and the middle-Tertiary age Ponce Limestone and Juana Diaz Formation (Giusti, 1968). The hydraulic properties of the Ponce Limestone in the Juana Diaz area are unknown, and the Juana Diaz Formation is a unit of poor permeability due to its high clay content. Consequently, the Ponce Limestone and the Juana Diaz Formation are generally considered to be the base of the alluvial aquifer in the Juana Diaz area with ground-water flow occurring primarily within the alluvial deposits. The potentiometric-surface map of the alluvial aquifer was delineated using ground-water level measurements taken at existing wells. The water-level measurements were taken at wells that were either not pumping during the survey or were shut down for a brief period. In the latter case, a recovery period of 30 minutes was allowed for the drawdown in the wellbore to achieve a near static level position representative of the aquifer at the measurement point. Land-surface altitude from U.S. Geological Survey (USGS) 1:20,000 scale topographic maps (Playa de Ponce, Ponce, Rio Descalabrado, and Santa Isabel) were used to refer ground-water levels to mean sea level datum (National Geodetic Vertical Datum of 1929). In addition to the ground-water level measurements, the potentiometricsurface contours were delineated using hydrologic features, such as drainage ditches and saturated intermittent streams that were

  7. Novel LTCC-potentiometric microfluidic device for biparametric analysis of organic compounds carrying plastic antibodies as ionophores: application to sulfamethoxazole and trimethoprim.

    Science.gov (United States)

    Almeida, S A A; Arasa, E; Puyol, M; Martinez-Cisneros, C S; Alonso-Chamarro, J; Montenegro, M C B S M; Sales, M G F

    2011-12-15

    Monitoring organic environmental contaminants is of crucial importance to ensure public health. This requires simple, portable and robust devices to carry out on-site analysis. For this purpose, a low-temperature co-fired ceramics (LTCC) microfluidic potentiometric device (LTCC/μPOT) was developed for the first time for an organic compound: sulfamethoxazole (SMX). Sensory materials relied on newly designed plastic antibodies. Sol-gel, self-assembling monolayer and molecular-imprinting techniques were merged for this purpose. Silica beads were amine-modified and linked to SMX via glutaraldehyde modification. Condensation polymerization was conducted around SMX to fill the vacant spaces. SMX was removed after, leaving behind imprinted sites of complementary shape. The obtained particles were used as ionophores in plasticized PVC membranes. The most suitable membrane composition was selected in steady-state assays. Its suitability to flow analysis was verified in flow-injection studies with regular tubular electrodes. The LTCC/μPOT device integrated a bidimensional mixer, an embedded reference electrode based on Ag/AgCl and an Ag-based contact screen-printed under a micromachined cavity of 600 μm depth. The sensing membranes were deposited over this contact and acted as indicating electrodes. Under optimum conditions, the SMX sensor displayed slopes of about -58.7 mV/decade in a range from 12.7 to 250 μg/mL, providing a detection limit of 3.85 μg/mL and a sampling throughput of 36 samples/h with a reagent consumption of 3.3 mL per sample. The system was adjusted later to multiple analyte detection by including a second potentiometric cell on the LTCC/μPOT device. No additional reference electrode was required. This concept was applied to Trimethoprim (TMP), always administered concomitantly with sulphonamide drugs, and tested in fish-farming waters. The biparametric microanalyzer displayed Nernstian behaviour, with average slopes -54.7 (SMX) and +57.8 (TMP) m

  8. iMS2Flux – a high–throughput processing tool for stable isotope labeled mass spectrometric data used for metabolic flux analysis

    Directory of Open Access Journals (Sweden)

    Poskar C Hart

    2012-11-01

    Full Text Available Abstract Background Metabolic flux analysis has become an established method in systems biology and functional genomics. The most common approach for determining intracellular metabolic fluxes is to utilize mass spectrometry in combination with stable isotope labeling experiments. However, before the mass spectrometric data can be used it has to be corrected for biases caused by naturally occurring stable isotopes, by the analytical technique(s employed, or by the biological sample itself. Finally the MS data and the labeling information it contains have to be assembled into a data format usable by flux analysis software (of which several dedicated packages exist. Currently the processing of mass spectrometric data is time-consuming and error-prone requiring peak by peak cut-and-paste analysis and manual curation. In order to facilitate high-throughput metabolic flux analysis, the automation of multiple steps in the analytical workflow is necessary. Results Here we describe iMS2Flux, software developed to automate, standardize and connect the data flow between mass spectrometric measurements and flux analysis programs. This tool streamlines the transfer of data from extraction via correction tools to 13C-Flux software by processing MS data from stable isotope labeling experiments. It allows the correction of large and heterogeneous MS datasets for the presence of naturally occurring stable isotopes, initial biomass and several mass spectrometry effects. Before and after data correction, several checks can be performed to ensure accurate data. The corrected data may be returned in a variety of formats including those used by metabolic flux analysis software such as 13CFLUX, OpenFLUX and 13CFLUX2. Conclusion iMS2Flux is a versatile, easy to use tool for the automated processing of mass spectrometric data containing isotope labeling information. It represents the core framework for a standardized workflow and data processing. Due to its flexibility

  9. A polymeric liquid membrane electrode responsive to 3,3',5,5'-tetramethylbenzidine oxidation for sensitive peroxidase/peroxidase mimetic-based potentiometric biosensing.

    Science.gov (United States)

    Wang, Xuewei; Yang, Yangang; Li, Long; Sun, Mingshuang; Yin, Haogen; Qin, Wei

    2014-05-06

    The oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) has great utility in bioanalysis such as peroxidase/peroxidase mimetic-based biosensing. In this paper, the behaviors of TMB oxidation intermediates/products in liquid/liquid biphasic systems have been investigated for the first time. The free radical, charge transfer complex, and diimine species generated by TMB oxidation are all positively charged under acidic and near-neutral conditions. Electron paramagnetic resonance and visible absorbance spectroscopy data demonstrate that these cationic species can be effectively transferred from an aqueous phase into a water-immiscible liquid phase functionalized by an appropriate cation exchanger. Accordingly, sensitive potential responses of TMB oxidation have been obtained on a cation exchanger-doped polymeric liquid membrane electrode under mildly acidic and near-neutral conditions. By using the membrane electrode responsive to TMB oxidations, two sensitive potentiometric biosensing schemes including the peroxidase-labeled sandwich immunoassay and G-quadruplex DNAzyme-based DNA hybridization assay have been developed. The obtained detection limits for the target antigen and DNA are 0.02 ng/mL and 0.1 nM, respectively. Coupled with other advantages such as low cost, high reliability, and ease of miniaturization and integration, the proposed polymeric liquid membrane electrode holds great promise as a facile and efficient transducer for TMB oxidation and related biosensing applications.

  10. Simultaneous Analysis of Monovalent Anions and Cations with a Sub-Microliter Dead-Volume Flow-Through Potentiometric Detector for Ion Chromatography

    Science.gov (United States)

    Dumanli, Rukiye; Attar, Azade; Erci, Vildan; Isildak, Ibrahim

    2016-01-01

    A microliter dead-volume flow-through cell as a potentiometric detector is described in this article for sensitive, selective and simultaneous detection of common monovalent anions and cations in single column ion chromatography for the first time. The detection cell consisted of less selective anion- and cation-selective composite membrane electrodes together with a solid-state composite matrix reference electrode. The simultaneous separation and sensitive detection of sodium (Na+), potassium (K+), ammonium (NH4+), chloride (Cl−) and nitrate (NO3−) in a single run was achieved by using 98% 1.5 mM MgSO4 and 2% acetonitrile eluent with a mixed-bed ion-exchange separation column without suppressor column system. The separation and simultaneous detection of the anions and cations were completed in 6 min at the eluent flow-rate of 0.8 mL/min. Detection limits, at S/N = 3, were ranged from 0.2 to 1.0 µM for the anions and 0.3 to 3.0 µM for the cations, respectively. The developed method was successfully applied to the simultaneous determination of monovalent anions and cations in several environmental and biological samples. PMID:26786906

  11. High-efficient method for spectrometric data real time processing with increased resolution of a measuring channel

    International Nuclear Information System (INIS)

    Ashkinaze, S.I.; Voronov, V.A.; Nechaev, Yu.I.

    1988-01-01

    Solution of reduction problem as a mean to increase spectrometric tract resolution when it is realized using the digit-by-digit modified method and special strategy, significantly reducing the time of processing, is considered. The results presented confirm that the complex measurement tract plus microcomputer is equivalent to the use of the tract with a higher resolution, and the use of the digit-by-digit modified method permits to process spectrometric information in real time scale

  12. Novel atomic absorption spectrometric and rapid spectrophotometric methods for the quantitation of paracetamol in saliva: application to pharmacokinetic studies.

    Science.gov (United States)

    Issa, M M; Nejem, R M; El-Abadla, N S; Al-Kholy, M; Saleh, Akila A

    2008-01-01

    A novel atomic absorption spectrometric method and two highly sensitive spectrophotometric methods were developed for the determination of paracetamol. These techniques based on the oxidation of paracetamol by iron (III) (method I); oxidation of p-aminophenol after the hydrolysis of paracetamol (method II). Iron (II) then reacts with potassium ferricyanide to form Prussian blue color with a maximum absorbance at 700 nm. The atomic absorption method was accomplished by extracting the excess iron (III) in method II and aspirates the aqueous layer into air-acetylene flame to measure the absorbance of iron (II) at 302.1 nm. The reactions have been spectrometrically evaluated to attain optimum experimental conditions. Linear responses were exhibited over the ranges 1.0-10, 0.2-2.0 and 0.1-1.0 mug/ml for method I, method II and atomic absorption spectrometric method, respectively. A high sensitivity is recorded for the proposed methods I and II and atomic absorption spectrometric method value indicate: 0.05, 0.022 and 0.012 mug/ml, respectively. The limit of quantitation of paracetamol by method II and atomic absorption spectrometric method were 0.20 and 0.10 mug/ml. Method II and the atomic absorption spectrometric method were applied to demonstrate a pharmacokinetic study by means of salivary samples in normal volunteers who received 1.0 g paracetamol. Intra and inter-day precision did not exceed 6.9%.

  13. Polarographic and potentiometric studies on some binary and ternary complex systems of dioxouranium(VI)

    International Nuclear Information System (INIS)

    Janarthanam, M.; Sivasankar, B.; Rengaraj, K.; Nair, M.S.

    1995-01-01

    The relative coordinating abilities of donor sites in the potentially tridentate ligands viz., asparagine, glutamine, aspartic acid and glutamic acid towards uranyl ion have been investigated by polarographic and pH-metric techniques. The metal ion forms 1:2 complexes under polarographic conditions. However, only 1:1 complex is observed under pH-metric conditions, where 1:2 complexes do not proceed due to extensive hydrolysis of the metal ion. The relative variations of ΔE 1/2 with pH and ligand concentration supported by conductometric titration data indicate that the primary amino groups in the amino acids are not involved in coordination with uranyl ion. Further, the amide groups in asparagine and glutamine also do not participate in coordination thus rendering these ligands unidentate. In aspartic and glutamic acid complexes, seven- and eight- membered chelate rings are formed involving two terminal carboxyl groups. The mixed ligand complex equilibria of uranyl ion involving aspartic acid/glutamic acid as primary ligands (A) and maleic acid, malonic acid, succinic acid and lactic acid as secondary ligands (B) have also been studied by computer based numerical evaluation of pH titration data. The concentration profiles have indicated the favorability of the formation of ternary complexes in general as reflected in the Δlog K values. (author). 10 refs., 1 fig., 1 tab

  14. Highly selective direct determination of chlorate ions by using a newly developed potentiometric electrode based on modified smectite.

    Science.gov (United States)

    Topcu, Cihan

    2016-12-01

    A novel polyvinyl chloride membrane chlorate (ClO 3 - ) selective electrode based on modified smectite was developed for the direct determination of chlorate ions and the potentiometric performance characteristics of its were examined. The best selectivity and sensitivity for chlorate ions were obtained for the electrode membrane containing ionophore/polyvinylchloride/o-nitrophenyloctylether in composition of 12/28/60 (w/w%). The proposed electrode showed a Nernstian response toward chlorate ions at pH=7 in the concentration range of 1×10 -7 -1×10 -1 M and the limit of detection was calculated as 9×10 -8 M from the constructed response plot. The linear slope of the electrode was -61±1mVdecade -1 for chlorate activity in the mentioned linear working range. The selectivity coefficients were calculated according to both the matched potential method and the separate solution method. The calculated selectivity coefficients showed that the electrode performed excellent selectivity for chlorate ions. The potentiometric response of electrode toward chlorate ions was found to be highly reproducible. The electrode potential was stable between pH=4-10 and it had a dynamic response time of <5s. The potentiometric behavior of the electrode in partial non-aqueous medium was also investigated and the obtained results (up to 5% (v/v) alcohol) were satisfactory. The proposed electrode was used during 15 weeks without any significant change in its potential response. Additionally, the electrode was very useful in water analysis studies such as dam water, river water, tap water, and swimming pool water where the direct determination of chlorate ions was required. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Potentiometric Determination of Ketotifen Fumarate in Pharmaceutical Preparations and Urine Using Carbon Paste and PVC Membrane Selective Electrodes

    Directory of Open Access Journals (Sweden)

    Eman Y. Z. Frag

    2011-01-01

    Full Text Available This study compares between unmodified carbon paste (CPE; the paste has no ion pair and polyvinyl chloride (PVC membrane selective electrodes that were used in potentiometric determination of ketotifen fumarate (KTF, where sodium tetraphenylborate (NaTPB was used as titrant. The performance characteristics of these sensors were evaluated according to IUPAC recommendations which reveal a fast, stable, and linear response for KTF over the concentration range of 10−7 to 10−2 mol L−1. The electrodes show Nernstian slope value of 52.51±0.20 and 51.51±0.25 mV decade−1 for CPE and PVC membrane electrodes at 30∘C, respectively. The potential is nearly stable over the pH range 3.0–6.0 and 2.0–7.0 for CPE and PVC membrane electrodes, respectively. Selectivity coefficient values towards different inorganic cations, sugars, and amino acids reflect high selectivity of the prepared electrodes. The electrodes responses at different temperatures were also studied, and long operational lifetime of 12 and 5 weeks for CPE and PVC membrane electrodes, respectively, were found. These are used for determination of ketotifen fumarate using potentiometric titration, calibration, and standard addition methods in pure samples, its pharmaceutical preparations (Zaditen tablets, and biological fluid (urine. The direct potentiometric determination of KTF using the proposed sensors gave recoveries % of 98.97±0.53 and 98.62±0.74 with RSD 1.42 and 0.63% for CPE and PVC membrane selective electrodes, respectively. Validation of the method shows suitability of the proposed sensors for use in quality control assessment of KTF. The obtained results were in a good agreement with those obtained using the reported spectrophotometric method.

  16. Potentiometric determination of ketotifen fumarate in pharmaceutical preparations and urine using carbon paste and PVC membrane selective electrodes.

    Science.gov (United States)

    Frag, Eman Y Z; Mohamed, Gehad G; Khalil, Mohamed M; Hwehy, Mohammad M A

    2011-01-01

    This study compares between unmodified carbon paste (CPE; the paste has no ion pair) and polyvinyl chloride (PVC) membrane selective electrodes that were used in potentiometric determination of ketotifen fumarate (KTF), where sodium tetraphenylborate (NaTPB) was used as titrant. The performance characteristics of these sensors were evaluated according to IUPAC recommendations which reveal a fast, stable, and linear response for KTF over the concentration range of 10(-7) to 10(-2) mol L(-1). The electrodes show Nernstian slope value of 52.51 ± 0.20 and 51.51 ± 0.25 mV decade(-1) for CPE and PVC membrane electrodes at 30°C, respectively. The potential is nearly stable over the pH range 3.0-6.0 and 2.0-7.0 for CPE and PVC membrane electrodes, respectively. Selectivity coefficient values towards different inorganic cations, sugars, and amino acids reflect high selectivity of the prepared electrodes. The electrodes responses at different temperatures were also studied, and long operational lifetime of 12 and 5 weeks for CPE and PVC membrane electrodes, respectively, were found. These are used for determination of ketotifen fumarate using potentiometric titration, calibration, and standard addition methods in pure samples, its pharmaceutical preparations (Zaditen tablets), and biological fluid (urine). The direct potentiometric determination of KTF using the proposed sensors gave recoveries % of 98.97 ± 0.53 and 98.62 ± 0.74 with RSD 1.42 and 0.63% for CPE and PVC membrane selective electrodes, respectively. Validation of the method shows suitability of the proposed sensors for use in quality control assessment of KTF. The obtained results were in a good agreement with those obtained using the reported spectrophotometric method.

  17. The measurement of mass spectrometric peak height ratio of helium isotope in trace samples

    International Nuclear Information System (INIS)

    Sun Mingliang

    1989-01-01

    An experiment study on the measurement of mass spectrometric peak height ratio of helium isotope in the trace gaseous sample is discussed by using the gas purification line designed by the authors and model VG-5400 static-vacuum noble gas mass spectrometer imported and air helium as a standard. The results show that the amount of He and Ne in natural gas sample is 99% after purification. When the amount of He in Mass Spectrometer is more than 4 x 10 -7 cm 3 STP, it's sensitivity remains stable, about 10 -4 A/cm 3 STP He and the precision of 3 He/ 4 He ratio within the following 17 days is 1.32%. The 'ABA' pattern and experiment condition in the measurement of mass spectrometric peak height ratio of He isotope are presented

  18. New FORTRAN computer programs to acquire and process isotopic mass-spectrometric data

    International Nuclear Information System (INIS)

    Smith, D.H.

    1982-08-01

    The computer programs described in New Computer Programs to Acquire and Process Isotopic Mass Spectrometric Data have been revised. This report describes in some detail the operation of these programs, which acquire and process isotopic mass spectrometric data. Both functional and overall design aspects are addressed. The three basic program units - file manipulation, data acquisition, and data processing - are discussed in turn. Step-by-step instructions are included where appropriate, and each subsection is described in enough detail to give a clear picture of its function. Organization of file structure, which is central to the entire concept, is extensively discussed with the help of numerous tables. Appendices contain flow charts and outline file structure to help a programmer unfamiliar with the programs to alter them with a minimum of lost time

  19. Standard test methods for chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade boron carbide

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2004-01-01

    1.1 These test methods cover procedures for the chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade boron carbide powder and pellets to determine compliance with specifications. 1.2 The analytical procedures appear in the following order: Sections Total Carbon by Combustion and Gravimetry 7-17 Total Boron by Titrimetry 18-28 Isotopic Composition by Mass Spectrometry 29-38 Chloride and Fluoride Separation by Pyrohydrolysis 39-45 Chloride by Constant-Current Coulometry 46-54 Fluoride by Ion-Selective Electrode 55-63 Water by Constant-Voltage Coulometry 64-72 Impurities by Spectrochemical Analysis 73-81 Soluble Boron by Titrimetry 82-95 Soluble Carbon by a Manometric Measurement 96-105 Metallic Impurities by a Direct Reader Spectrometric Method 106-114

  20. The interlaboratory experiment IDA-72 on mass spectrometric isotope dilution analysis. Vol. 2

    International Nuclear Information System (INIS)

    Beyrich, W.; Drosselmeyer, E.

    1975-07-01

    Volume II of the report on the IDA-72 experiment contains papers written by different authors on a number of special topics connected with the preparation, performance and evaluation of the interlaboratory test. In detail the sampling procedures for active samples of the reprocessing plant and the preparation of inactive reference and spike solution from standard material are described as well as new methods of sample conditioning by evaporation. An extra chapter is devoted to the chemical sample treatment as a preparation for mass spectrometric analysis of the U and Pu content of the solutions. Special topics are also methods for mass discrimination corrections, α-spectrometer measurements as a supplement for the determination of Pu-238 and the comparison of concentration determinations by mass spectrometric isotope dilution analysis with those performed by X-ray fluorescence spectrometry. The last part of this volume contains papers connected with the computerized statistical evaluation of the high number of data. (orig.) [de

  1. [Determination of trace cobalt in human urine by graphite furnace atomic absorption spectrometr].

    Science.gov (United States)

    Zhong, L X; Ding, B M; Jiang, D; Liu, D Y; Yu, B; Zhu, B L; Ding, L

    2016-05-20

    To establish a method to determine cobalt in human urine by graphite furnace atomic absorption spectrometry. Urine with 2% nitric acid diluted two-fold, to quantify the curve, graphite furnace atomic absorption spectrometric detection. Co was linear within 2.5~40.0 ng/ml with r>0.999. Spike experiment showed that Co received good recovery rate, which was 90.8%~94.8%. Intra-assay precisions were 3.2%~5.1% for Co, inter-assay precisions were 4.4%~5.2% for Co. The method by using graphite furnace atomic absorption spectrometr to determine urine Co was fast, accurate and with low matrix effect. It could meet the requirement in GBZ/T 210.5-2008.

  2. The fast gamma spectrometric method of the Am-241 determination in Chernobyl restricted zone soils

    International Nuclear Information System (INIS)

    Gleisberg, B.; Lukachina, V.V.; Kirsenko, V.N.; Tepikin, V.E.; Rajevsky, V.S.; Libman, V.A.; Stoljarevsky, I.P.; Isajev, A.G.

    1997-01-01

    The known methods of the 241 Am contents determination in environmental objects, as a rule, is based on ion-chromatographic or extraction separation techniques. This approach reflects widespread opinion, that only the α-spectrometric analysis termination is suitable to ensure necessary sensitivity of the overall method of 241 Am actively determination. Really, the minimal detectable activity for such methods is about 0.05 Bq/kg (considering that Am is usually concentrated during separation procedure). However, because of α-spectrometry does not permit to separate the α-peaks of the 241 Am, and 238 Pu, but also in view of high requests to the α-spectrometric specimen purity, the multistage and laborious chemical procedures to separate 241 Am from plutonium radionuclides and other elements (with a thorough control of each separation stage) are needed

  3. Silver ion recognition using potentiometric sensor based on recently synthesized isoquinoline-1,3-dione derivatives

    Directory of Open Access Journals (Sweden)

    AJAR KAMAL

    2012-08-01

    Full Text Available The four derivatives of isoquinoline-1,3-dione based on β-lactum (I-IV, have been explored as neutral ionophores for preparing poly(vinylchloride based polymeric membrane electrodes (PME selective to silver(I ions. The addition of sodium tetraphenylborate (NaTPB and dioctylsebacate (DOS as a plasticizer was found to improve the performance of ion selective electrodes. The best performance was obtained with PME-1 based on ionophore I having composition: ionophore (9.2 mg, PVC (100.1 mg, DOS (201.1 mg and NaTPB (1.5 mg in 5 mL tetrahydrofuran. The electrode response was linear with Nernstian slope of 58.44 mV/decade in the concentration range of 1.0 x 10-1 M to 5.0 x 10-6 M and detection limit of 5.83 x 10-6 M. It performs satisfactorily over wide pH range of 1.0-5.5. The proposed sensor can be used over a period of more than three months without any significant drift in potential and shows good selectivity to silver(I ion over a number of cations especially with no interference of mercury(II ions. Sharp end point was obtained when the sensor was used as an indicator electrode for the potentiometric titration of silver(I ions with chloride ions and therefore this electrode (PME-1 could be used for quantitative determination of silver(I ion in synthetic water, silver foil and dental amalgam samples.

  4. Potentiometric sensing of iodide using polymeric membranes of microwave stabilized β-AgI

    International Nuclear Information System (INIS)

    James, Dhanya; Rao, T. Prasada

    2012-01-01

    Highlights: ► Stable β-phase was obtained by post MW irradiation of AgI precipitate. ► Constructed ISEby dispersing stable β-AgI crystals in polyvinyl chloride. ► Designed iodide ISE exhibited wide linear range and fast response. ► Highly selective with selectivity factors less than 10 −6 . ► Successfully applied to natural waters, table salt and human urine samples. - Abstract: A polymer based heterogeneous ion selective electrode (ISE) membrane was fabricated for the potentiometric sensing of iodide. The sensing element used for the preparation of the ISE membrane was microwave stabilized β-AgI. Because microwave energy was found to be beneficial for causing hysteresis at the phase transition temperature of AgI, an attempt has been made to prepare stable and conductive β-AgI crystals by post microwave irradiation under high pressure. A conventionally precipitated AgI based ISE was also fabricated for comparative studies. The β-AgI based ISE could respond to a wide range of iodide concentrations (1 × 10 −8 to 1 M) within 60 s with a detection limit of 10 nM. The ISE gave stable response to iodide ions in a pH range of 2.0–8.0 and was highly selective in the presence of various interfering ions. The performance of the proposed iodide ISE in the analysis of natural and seawater samples was encouraging, and the determination of iodide in table salt and human urine samples was explained using the developed sensor.

  5. Dual functional extracellular recording using a light-addressable potentiometric sensor for bitter signal transduction.

    Science.gov (United States)

    Du, Liping; Wang, Jian; Chen, Wei; Zhao, Luhang; Wu, Chunsheng; Wang, Ping

    2018-08-31

    This paper presents a dual functional extracellular recording biosensor based on a light-addressable potentiometric sensor (LAPS). The design and fabrication of this biosensor make it possible to record both extracellular membrane potential changes and ATP release from a single taste bud cell for the first time. For detecting ATP release, LAPS chip was functionalized with ATP-sensitive DNA aptamer by covalent immobilization. Taste bud cells isolated from rat were cultured on LAPS surface. When the desired single taste bud cell was illuminated by modulated light, ATP release from single taste bud cells can be measured by recording the shifts of bias voltage-photocurrent curves (I-V curves) when the LAPS chip is working in discrete mode. On the other hand, extracellular membrane potential changes can be monitored by recording the fluctuation of LAPS photocurrent when the LAPS chip is working in continuous mode. The results show this biosensor can effectively record the enhancive effect of the bitter substance and inhibitory effect of the carbenoxolone (CBX) on the extracellular membrane potential changes and ATP release of single taste bud cells. In addition, the inhibitory effect of CBX also confirms LAPS extracellular recordings are originated from bitter signal transduction. It is proved this biosensor is suitable for extracellular recording of ATP release and membrane potential changes of single taste bud cells. It is suggested this biosensor could be applied to investigating taste signal transduction at the single-cell level as well as applied to other types of cells which have similar functions to taste bud cells. Copyright © 2018 Elsevier B.V. All rights reserved.

  6. Simultaneous determination of equivalence volumes and acid dissociation constants from potentiometric titration data.

    Science.gov (United States)

    Papanastasiou, G; Ziogas, I

    1995-06-01

    New iterative methods for analysis of potentiometric titration data of (a) mixtures of weak monoprotic acids with their conjugate bases, (b) solutions of polyprotic (di- and triprotic) acids, and (c) mixtures of two diprotic acids are presented. These methods, using data exclusively resulting from the acidic region of the titration curve permits the accurate determination of the analytical concentration of one or more acids even if the titration is stopped well before the end point of the titration. For the titration of a solution containing a conjugate acid/base pair, the proposed procedure enables the extraction of the initial composition of the mixture, as well as the dissociation constant of the concerned acid. Thus, it is possible by this type of analysis to distinguish whether a weak acid has been contaminated by a strong base and define the extent of the contamination. On the other hand, for the titration of polyprotic acids, the proposed approach enables the extraction of the accurate values of the equivalence volume and the dissociation constants K(i) even when the ionization stages overlap. Finally, for the titration of a mixture of two diprotic acids the proposed procedure enables the determination of the composition of the mixture even if the sum of the concentrations of the acids is not known. This method can be used in the analysis of solutions containing two diastereoisomeric forms of a weak diprotic acid. The test of the proposed procedures by means of ideal and Monte Carlo simulated data revealed that these methods are fairly applicable even when the titration data are considerably obscured by 'noise' or contain an important systematic error. The proposed procedures were also successfully applied to experimental titration data.

  7. Novel biomimetic composite material for potentiometric screening of acetylcholine, a neurotransmitter in Alzheimer's disease.

    Science.gov (United States)

    Sacramento, Ana S; Moreira, Felismina T C; Guerreiro, Joana L; Tavares, Ana P; Sales, M Goreti F

    2017-10-01

    This work describes a novel approach to produce an antibody-like biomimetic material. It includes preparing composite imprinted material never presented before, with highly conductive support nanostructures and assembling a high conductivity polymeric layer at low temperature. Overall, such highly conductive material may enhance the final features of electrically-based devices. Acetylcholine (ACh) was selected as target analyte, a neurotransmitter of importance in Alzheimer's disease. Potentiometric transduction was preferred, allowing quick responses and future adaptation to point-of-care requirements. The biomimetic material was obtained by bulk polymerization, where ACh was placed in a composite matrix of multiwalled carbon nanotubes (MWCNTs) and aniline (ANI). Subsequent polymerization, initiated by radical species, yielded a polymeric structure of polyaniline (PANI) acting as physical support of the composite. A non-imprinted material (NIM) having only PANI/MWCNT (without ACh) has been prepared for comparison of the biomimetic-imprinted material (BIM). RAMAN and Fourier Transform Infrared spectroscopy (FTIR), Transmission Electron microscopy (TEM), and Scanning Electron microscope (SEM) analysis characterized the structures of the materials. The ability of this biomaterial to rebind ACh was confirmed by including it as electroactive compound in a PVC/plasticizer mixture. The membranes with imprinted material and anionic additive presented the best analytical characteristics, with a sensitivity of 83.86mV decade -1 and limit of detection (LOD) of 3.45×10 -5 mol/L in HEPES buffer pH4.0. Good selectivity was observed against creatinine, creatine, glucose, cysteine and urea. The electrodes were also applied on synthetic serum samples and seemed a reliable tool for screening ACh in synthetic serum samples. The overall performance showed fast response, reusability, simplicity and low price. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Potentiometric determination of moxifloxacin in some pharmaceutical formulation using PVC membrane sensors.

    Science.gov (United States)

    Hefnawy, Mohammed M; Homoda, Atef M; Abounassif, Mohammed A; Alanazi, Amer M; Al-Majed, Abdulrahaman; Mostafa, Gamal A

    2014-01-01

    The construction and electrochemical response characteristics of Poly (vinyl chloride) membrane sensors for moxifloxacin HCl (MOX) are described. The sensing membranes incorporate ion association complexes of moxifloxacin cation and sodium tetraphenyl borate (NaTPB) (sensor 1), phosphomolybdic acid (PMA) (sensor 2) or phosphotungstic acid (PTA) (sensor 3) as electroactive materials. The sensors display a fast, stable and near-Nernstian response over a relative wide moxifloxacin concentration range (1 × 10(-2) - 4.0 × 10(-6), 1 × 10(-2) - 5.0 × 10(-6), 1 × 10(-2) - 5.0 × 10(-6) M), with detection limits of 3 × 10(-6), 4 × 10(-6) and 4.0 × 10(-6) M for sensor 1, 2 and 3, respectively over a pH range of 6.0 - 9.0. The sensors show good discrimination of moxifloxacin from several inorganic and organic compounds. The direct determination of 400 μg/ml of moxifloxacin show an average recovery of 98.5, 99.1 and 98.6% and a mean relative standard deviation of 1.8, 1.6 and 1.8% for sensors 1, 2 and 3 respectively. The proposed sensors have been applied for direct determination of moxifloxacin in some pharmaceutical preparations. The results obtained by determination of moxifloxacin in tablets using the proposed sensors are comparable favorably with those obtained using the US Pharmacopeia method. The sensors have been used as indicator electrodes for potentiometric titration of moxifloxacin.

  9. Potentiometric titration of selenic and telluric acids with titanium(III) chloride in nonaqueous solvents

    International Nuclear Information System (INIS)

    Yoshimura, Chozo; Miyamoto, Kiyoshige

    1985-01-01

    Selenic and Telluric acids were titrated potentiometrically with titanium(III) chloride solution by using Pt-Cu · Hg bimetallic electrodes in nonaqueous solvents such as N, N-dimethyl-formamide (DMF), dimethyl sulfoxide (DMSO), isopropyl alcohol (IPA) and the mixtures of these solvents. It was found that selenic and telluric acids were titrated directly at room temperature in DMF solution without hydrochloric acid. The molar ratios of selenic and telluric acids to titanium(III) chloride was 1 : 6. However, the corresponding reactions to SeO 4 2- → SeO 3 2- or TeO 4 2- → TeO 3 2- were not confirmed in the titration curve in DMF. In the titration of selenic acid in mixed solvents of DMF and IPA in 1 : 1 or 1 : 2 ratio, two steps were observed. The first and the second steps were appeared on the titration curve at molar ratios of 1 : 2 and 1 : 6, respectively. It was interpreted that the first step corresponded to the intermediate reaction of SeO 4 2- → SeO 3 2- . Mixed solution of selenic and telluric acids were determined by the proposed method. Three steps were observed on the titration curve. It was interpreted that the first, second and third steps corresponded to the reaction of SeO 4 2- → SeO 3 2- , SeO 3 2- → Se(0), and TeO 4 2- → Te(0), respectively. Less than 5 % of water gave no influence on the titration. (author)

  10. Investigation of uranyl-ion hydrolysis in uranyl pertechnetate and uranyl perchlorates solutions by two-phases potentiometric titration method

    International Nuclear Information System (INIS)

    Volk, V.I.; Belikov, A.D.

    1977-01-01

    The applicability of the method of two-phase potentiometric titration for studying hydrolysis of multi-charge ions has been shown. Hydrolysis of uranyl-ion has been investigated and hydrolysis constants in the solutions of uranyl pertechnetate and perchlorate have been calculated equal to (6.2+-0.15)x10 -5 and (9.25+-0.5)10 -5 , respectively. Infrared spectra of the initial crystallohydrates of uranyl pertechnetate and perchlorate has been analyzed. The data on hydrolysis of an uranyl-ion and IR spectra of crystallohydrates of the investigated salts have revealed the ability of pertechnetate ion to complexing with an uranyl group

  11. Investigation of interaction of phosphorotungstenvanadium heteropolyacids with sodium hydroxide by the methods of calorimetric and potentiometric titration

    International Nuclear Information System (INIS)

    Ganelina, E.Sh.; Borgoyakov, S.A.

    1985-01-01

    Interaction of phosphorotungstenvanadium heteropolyacids (HPA) with alkali (NaOH) is studied by the methods of calorimetric and potentiometric titration. Three stages are singled out: 1) neutralization of ''strong'' hydrogen atoms with a constant thermal effect of 52.0+-1.6 kJ/mol; 2) neutralization of ''weak'' protons, which acidity constant is of order 10 -2 ; 3) interaction of NaOH with hydrogen atoms combined with the internal sphere of HPA, and completed by HPA destruction. The data obtained are compared with the results, calculating the composition of polymer particles inside HPA, and they are discussed from the view point of their micellar structure

  12. Accurate and precise determination of 2-25mg amounts of uranium by means of a special automatic potentiometric titration

    International Nuclear Information System (INIS)

    Slanina, J.; Bakker, F.; Groen, A.J.P.; Lingerak, W.A.

    1978-01-01

    A precise and accurate potentiometric titration of 2-25 mg of uranium is described. The uranium is reduced to U(IV) according to the method of Eberle et al. [3], and titrated with 0.05 N potassium dichromate, using a platinum indicator electrode. During the sample preparation the walls of the titration vessel are cleaned by centrifugation. To avoid overshoot of the set point a special differentiator is described, that interrupts the titration until equilibrium is reached. The precision of the method is 0.02%, the accuracy is better than 0.04% rel. Each titration takes 5 min. (orig.) [de

  13. Aspects of optical fibers and spectrometric sensors in chemical process and industrial environments

    International Nuclear Information System (INIS)

    Boisde, G.; Perez, J.J.

    1988-01-01

    For on-line control, the two alternatives of automatic sample transfer and in situ remote analysis are discussed. New concepts are emerging from the possibilities offered by optical fibers. Absorption in the visible, UV and IR, fluorescence and Raman spectrometric techniques are examined. The state of the art of optodes and devices in chemical process control are given, with some examples of applications in nuclear plants

  14. Gamma-spectrometric examination of hot particles emitted during the Chernobyl accident

    International Nuclear Information System (INIS)

    Balashazy, I.; Szabadine-Szende, G.; Loerinc, M.; Zombori, P.

    1987-05-01

    Ge(Li) gamma-spectrometric examination of hot particles prepared from air filtered dust of Budapest air after the Chernobyl accident is presented. The method of separating hot particles is described and their concentration in the air is determined. The radioactive isotope composition of hot particles is discussed and compared with that of dust samples. Finally, the inhalation probability and radiation burden of hot particles are evaluated. (author)

  15. A method for exploring the distribution of radioelements at depth using gamma-ray spectrometric data

    International Nuclear Information System (INIS)

    Li Qingyang

    1997-01-01

    Based on the inherent relation between radioelements and terrestrial heat flow, theoretically shows the possibility of exploring the distribution of radioelements at depth using gamma-ray spectrometric data, and a data-processing and synthesizing method has been adopted to deduce the calculation formula. The practical application in the uranium mineralized area No. 2801 in Yunnan Province proves that this method is of practical value, and it has been successfully applied to the data processing and good results have been obtained

  16. Mass-spectrometric investigation of rare earth acetylacetonates dipivaloylmethanates and their adducts

    International Nuclear Information System (INIS)

    Gavrishzhuk, E.M.; Dzyubenko, N.G.; Martynenko, L.I.

    1985-01-01

    Peculiarities of fragmentation of molecular ions of rare earth acetylacetonates and dipivaloylmethanates under mass-spectrometric investigation of these compounds as well as their adducts with o-phenanthroline, α,α'-dipyridyl, triphenylphosphine oxide are considered in the given review. Similar data for identical derivants of some transitions metals are presented. Data on potentials of appearance and dissociation energy of basic ions in mass-spectra of the studied β-diketonates are analyzed

  17. Sensitive emission spectrometric method for the analysis of airborne particulate matter

    International Nuclear Information System (INIS)

    Sugimae, A.

    1975-01-01

    A rapid and sensitive emission spectrometric method for the routine analysis of airborne particulate matter collected on the glass fiber filter is reported. The method is a powder--dc arc technique involving no chemical pre-enrichment procedures. The elements--Ag, BA: Be, Bi, Cd, Co, Cr, Cu, Fe, Ga, La, Mn, Ni, Pb, Sn, V, Y, Yb, and Zn--were determined. (U.S.)

  18. Silver ion imprinted polymer nanobeads based on a aza-thioether crown containing a 1,10-phenanthroline subunit for solid phase extraction and for voltammetric and potentiometric silver sensors

    Energy Technology Data Exchange (ETDEWEB)

    Shamsipur, Mojtaba, E-mail: mshamsipur@yahoo.com [Department of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Hashemi, Beshare; Dehdashtian, Sara; Mohammadi, Moslem; Gholivand, Mohammad Bagher [Department of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Garau, Alessandra; Lippolis, Vito [Dipartimento di Scienze Chimiche e Geologiche, Universita' degli Studi di Cagliari, S.S. 554 Bivio per Sestu, 09042 Monserrato, CA (Italy)

    2014-12-10

    Highlights: • Preparation of Ag{sup +} imprinted polymeric nanobeads via precipitation polymerization. • Use of a mixed aza-thioether crown containing a 1,10-phenanthroline subunit a selective host for Ag{sup +} ion. • Highly selective, sensitive and fast recognition of traces of Ag{sup +} ions. • Use of the prepared Ag{sup +}-IIP for preparation of an Ag{sup +}-voltammetric sensor with LOD of 9.0 × 10{sup −10} M. • Use of the prepared Ag{sup +}-IIP for preparation of Ag{sup +}-ISEs with LOD of 1.2 × 10{sup −9} M 9.0 × 10{sup −10} M. - Abstract: A new nano-sized silver(I) ion-imprinted polymer (IIP) was prepared via precipitation copolymerization using ethyleneglycol dimethacrylate, as a cross-linking agent in the presence of Ag{sup +} and an aza-thioether crown containing a 1,10-phenanthroline subunit as a highly selective complexing agent. The imprint silver(I) ion was removed from the polymeric matrix using a 1.0 M HNO{sub 3} solution. The resulting powder material was characterized using IR spectroscopy and scanning electron microscopy. The SEM micrographs showed colloidal nanoparticles of about 52 nm and 75 nm in diameter and slightly irregular in shape for leached and unleached IIPs, respectively. The optimal pH for quantitative enrichment was 6.0 and maximum sorbent capacity of the prepared IIP for Ag{sup +} was 18.08 μmol g{sup −1}. The relative standard deviation and limit of detection (LOD = 3S{sub b}/m) for flame atomic absorption spectrometric determination of silver(I) ion, after its selective extraction by the prepared IIP nanobeads, were evaluated as 2.42% and 2.2 × 10{sup −8} M, respectively. The new Ag{sup +}-IIP was also applied as a suitable sensing element to the preparation of highly selective and sensitive voltammetric and potentiometric sensors for ultra trace detection of silver(I) ion in water samples, with limits of detection of 9.0 × 10{sup −10} and 1.2 × 10{sup −9} M, respectively.

  19. Potentiometric studies on some ternary complexes of Nd(III), Sm(III), Gd(III) and Ho(III) with cyclohexanediaminetetraacetic acid as primary ligand

    International Nuclear Information System (INIS)

    Marathe, D.G.; Munshi, K.N.

    1983-01-01

    The formation constants of the ternary complexes of neodymium(III), samarium(III), gadlonium(III) and holmium(III) with cyclohexanediaminetetraacetic acid (CyDTA) as primary ligand and dihydroxynaphthalene (DHN), dihydroxynaphthalene-6-sulphonic acid (DHNSA) and cateechol-3,5-disulphonic acid (CDSA) as secondary ligands have been investigated by potentiometric titration technique. The secondary ligands have been investigated by potentiometric titration technique. The values of formation constants of 1:1:1 ternary chelates are reported at three different temperatures, and at a fixed ionic strength, μ = 0.1 M (NaClO 4 ). (author)

  20. Uncertainty assessment in gamma spectrometric measurements of plutonium isotope ratios and age

    Energy Technology Data Exchange (ETDEWEB)

    Ramebaeck, H., E-mail: henrik.ramebeck@foi.se [Swedish Defence Research Agency, FOI, Division of CBRN Defence and Security, SE-901 82 Umea (Sweden); Chalmers University of Technology, Department of Chemical and Biological Engineering, Nuclear Chemistry, SE-412 96 Goeteborg (Sweden); Nygren, U.; Tovedal, A. [Swedish Defence Research Agency, FOI, Division of CBRN Defence and Security, SE-901 82 Umea (Sweden); Ekberg, C.; Skarnemark, G. [Chalmers University of Technology, Department of Chemical and Biological Engineering, Nuclear Chemistry, SE-412 96 Goeteborg (Sweden)

    2012-09-15

    A method for the assessment of the combined uncertainty in gamma spectrometric measurements of plutonium composition and age was evaluated. Two materials were measured. Isotope dilution inductively coupled plasma sector field mass spectrometry (ID-ICP-SFMS) was used as a reference method for comparing the results obtained with the gamma spectrometric method for one of the materials. For this material (weapons grade plutonium) the measurement results were in agreement between the two methods for all measurands. Moreover, the combined uncertainty in all isotope ratios considered in this material (R{sub Pu238/Pu239}, R{sub Pu240/Pu239}, R{sub Pu241/Pu239}, and R{sub Am241/Pu241} for age determination) were limited by counting statistics. However, the combined uncertainty for the other material (fuel grade plutonium) were limited by the response fit, which shows that the uncertainty in the response function is important to include in the combined measurement uncertainty of gamma spectrometric measurements of plutonium.