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Sample records for chromatographic peak capacities

  1. [A peak recognition algorithm designed for chromatographic peaks of transformer oil].

    PubMed

    Ou, Linjun; Cao, Jian

    2014-09-01

    In the field of the chromatographic peak identification of the transformer oil, the traditional first-order derivative requires slope threshold to achieve peak identification. In terms of its shortcomings of low automation and easy distortion, the first-order derivative method was improved by applying the moving average iterative method and the normalized analysis techniques to identify the peaks. Accurate identification of the chromatographic peaks was realized through using multiple iterations of the moving average of signal curves and square wave curves to determine the optimal value of the normalized peak identification parameters, combined with the absolute peak retention times and peak window. The experimental results show that this algorithm can accurately identify the peaks and is not sensitive to the noise, the chromatographic peak width or the peak shape changes. It has strong adaptability to meet the on-site requirements of online monitoring devices of dissolved gases in transformer oil.

  2. Mathematical functions for the representation of chromatographic peaks.

    PubMed

    Di Marco, V B; Bombi, G G

    2001-10-05

    About ninety empirical functions for the representation of chromatographic peaks have been collected and tabulated. The table, based on almost 200 references, reports for every function: (1) the most used name; (2) the most convenient equation, with the existence intervals for the adjustable parameters and for the independent variable; (3) the applications; (4) the mathematical properties, in relation to the possible applications. The list includes also equations originally proposed to represent peaks obtained in other analytical techniques (e.g. in spectroscopy), which in many instances have proved useful in representing chromatographic peaks as well; the built-in functions employed in some commercial peak-fitting software packages were included, too. Some of the most important chromatographic functions, i.e. the Exponentially Modified Gaussian, the Poisson, the Log-normal, the Edgeworth/Cramér series and the Gram/Charlier series, have been reviewed and commented in more detail.

  3. Accuracy of peak deconvolution algorithms within chromatographic integrators

    SciTech Connect

    Papas, A.N. ); Tougas, T.P. )

    1990-02-01

    The soundness of present-day algorithms to deconvolve overlapping skewed peaks was investigated. From simulated studies based on the exponentially modified Gaussian model (EMG), chromatographic peak area inaccuracies for unresolved peaks are presented for the two deconvolution methods, the tangent skim and the perpendicular drop method. These inherent inaccuracies, in many cases exceeding 50%, are much greater than those calculated from ideal Gaussian profiles. Multiple linear regression (MLR) was used to build models that predict the relative error for either peak deconvolution method. MLR also provided a means for determining influential independent variables, defining the required chromatographic relationships needed for prediction. Once forecasted errors for both methods are calculated, selection of either peak deconvolution method can be made by minimum errors. These selection boundaries are contrasted to method selection criteria of present data systems algorithms.

  4. High-capacity pressurized continuous chromatograph

    SciTech Connect

    Begovich, J.M.; Byers, C.H.; Sisson, W.G.

    1983-01-01

    Multicomponent liquid chromatographic separations have been achieved by using a slowly rotating annular bed of sorbent material. The feed material is continuously introduced at a stationary point at the top of the bed, and eluent is allowed to flow everwhere else around the annulus. The rotation of the sorbent bed causes the separation components to appear as helical bands, each of which has a characteristic, stationary exit point; hence the separation process is truly continuous. The concept has been developed primarily on a 279-mm-diam by 0.6-m-long device with a 12.7-mm-wide annulus. The effects of annulus width and diameter have been studied using the same device with annulus widths up to 114.3 mm. With this largest width, approximately 96% of the area available within the outer cylinder is devoted to the rotating sorbent bed. Further annulus-width studies have been pursued on units with 89- and 445-mm diameters. These geometric extensions to the basic concept allow extremely large capacity increases with minimal loss in separation and no increase in chromatograph diameter. The effects associated with increased feed concentration have also been studied. In this effort as well as in the annulus-width program, the separation of copper, nickel, and cobalt components from a carbonate solution was studied in detail. The nickel and cobalt components are found in the leach liquor of the Caron process for recovering nickel and cobalt from laterite ores. Nominally 50-..mu..m0-diam Dowex 50W-X8 cation exchange resin was used as the bed material. The nickel concentration of the feed was varied tenfold, from 136.1 to approximately 1400 meq/L. The combined effects of the bed loading and annulus width were studied and compared with nonlinear theory.

  5. High-capacity pressurized continuous chromatograph

    SciTech Connect

    Begovich, J.M.; Byers, C.H.; Sisson, W.G.

    1983-01-01

    Multicomponent liquid chromatographic separations have been achieved by using a slowly rotating annular bed of sorbent material. The feed material is continuously introduced at a stationary point at the top of the bed, and eluent is allowed to flow everywhere else around the annulus. The rotation of the sorbent bed causes the separated components to appear as helical bands, each of which has a characteristic, stationary exit point; hence the separation process is truly continuous. The concept has been developed primarily on a 279-mm-diam by 0.6-m-long device with a 12.7-mm-wide annulus. The effects of annulus width and diameter have been studied using the same device with annulus widths up to 114.3 mm. With this largest width, approximately 96% of the area available within the outer cylinder is devoted to the rotating sorbent bed. Further annulus-width studies have been pursued on units with 89- and 445-mm diameters. These geometric extensions to the basic concept allow extremely large capacity increases with minimal loss in separation and no increase in chromatograph diameter. The effects associated with increased feed concentration have also been studied. In this effort as well as in the annulus-width program, the separation of copper, nickel, and cobalt components from a carbonate solution was studied in detail. The nickel and cobalt components are found in the leach liquor of the Caron process for recovering nickel and cobalt from laterite ores. Nominally 50-..mu..m-diam Dowex 50W-X8 cation exchange resin was used as the bed material. The nickel concentration of the feed was varied tenfold, from 136.1 to approximately 1400 meq/L. The combined effects of the bed loading and annulus width were studied and compared with nonlinear theory. 17 references, 9 figures, 1 table.

  6. High-capacity pressurized continuous chromatograph

    SciTech Connect

    Begovich, J.M.; Byers, C.H.; Sisson, W.G.

    1983-01-01

    Multicomponent liquid chromatographic separations have been achieved by using a slowly rotating annular bed of sorbent material. The feed material is continuously introduced at a stationary point at the top of the bed, and eluent is allowed to flow everywhere else around the annulus. The rotation of the sorbent bed causes the separated components to appear as helical bands, each of which has a characteristic, stationary exit point; hence the separation process is truly continuous. The concept has been developed primarily on a 279-mm-diam by 0.6m-long device with a 12.7-mm-wide annulus. The effects of annulus width and diameter have been studied using the same device with annulus widths up to 114.3 mm. With this largest width, approximately 96% of the area available within the outer cylinder is devoted to the rotating sorbent bed. Further annulus-width studies have been pursued on units with 89- and 445-mm diameters. These geometric extensions to the basic concept allow extremely large capacity increases with minimal loss in separation and no increase in chromatograph diameter. The effects associated with increased feed concentration have also been studied. In this effort as well as in the annulus-width program, the separation of copper, nickel, and cobalt components from a carbonate solution was studied in detail. The nickel and cobalt components are found in the leach liquor of the Caron process for recovering nickel and cobalt from laterite ores. Nominally 50-..mu..m-diam Dowex 50W-X8 cation exchange resin was used as the bed material. The nickel concentration of the feed was varied tenfold, from 136.1 to approximately 1400 meq/L. The combined effects of the bed loading and annulus width were studied and compared with nonlinear theory. 9 figures, 1 table.

  7. The Calculation of Adsorption Isotherms from Chromatographic Peak Shapes

    ERIC Educational Resources Information Center

    Neumann, M. G.

    1976-01-01

    Discusses the relationship between adsorption isotherms and elution peak shapes in gas chromatography, and describes a laboratory experiment which involves the adsorption of hexane, cyclohexane, and benzene on alumina at different temperatures. (MLH)

  8. A simple multi-scale Gaussian smoothing-based strategy for automatic chromatographic peak extraction.

    PubMed

    Fu, Hai-Yan; Guo, Jun-Wei; Yu, Yong-Jie; Li, He-Dong; Cui, Hua-Peng; Liu, Ping-Ping; Wang, Bing; Wang, Sheng; Lu, Peng

    2016-06-24

    Peak detection is a critical step in chromatographic data analysis. In the present work, we developed a multi-scale Gaussian smoothing-based strategy for accurate peak extraction. The strategy consisted of three stages: background drift correction, peak detection, and peak filtration. Background drift correction was implemented using a moving window strategy. The new peak detection method is a variant of the system used by the well-known MassSpecWavelet, i.e., chromatographic peaks are found at local maximum values under various smoothing window scales. Therefore, peaks can be detected through the ridge lines of maximum values under these window scales, and signals that are monotonously increased/decreased around the peak position could be treated as part of the peak. Instrumental noise was estimated after peak elimination, and a peak filtration strategy was performed to remove peaks with signal-to-noise ratios smaller than 3. The performance of our method was evaluated using two complex datasets. These datasets include essential oil samples for quality control obtained from gas chromatography and tobacco plant samples for metabolic profiling analysis obtained from gas chromatography coupled with mass spectrometry. Results confirmed the reasonability of the developed method.

  9. Quantitative Metabolome Analysis Based on Chromatographic Peak Reconstruction in Chemical Isotope Labeling Liquid Chromatography Mass Spectrometry.

    PubMed

    Huan, Tao; Li, Liang

    2015-07-21

    Generating precise and accurate quantitative information on metabolomic changes in comparative samples is important for metabolomics research where technical variations in the metabolomic data should be minimized in order to reveal biological changes. We report a method and software program, IsoMS-Quant, for extracting quantitative information from a metabolomic data set generated by chemical isotope labeling (CIL) liquid chromatography mass spectrometry (LC-MS). Unlike previous work of relying on mass spectral peak ratio of the highest intensity peak pair to measure relative quantity difference of a differentially labeled metabolite, this new program reconstructs the chromatographic peaks of the light- and heavy-labeled metabolite pair and then calculates the ratio of their peak areas to represent the relative concentration difference in two comparative samples. Using chromatographic peaks to perform relative quantification is shown to be more precise and accurate. IsoMS-Quant is integrated with IsoMS for picking peak pairs and Zero-fill for retrieving missing peak pairs in the initial peak pairs table generated by IsoMS to form a complete tool for processing CIL LC-MS data. This program can be freely downloaded from the www.MyCompoundID.org web site for noncommercial use.

  10. Chromatographic multivariate quality control of pharmaceuticals giving strongly overlapped peaks based on the chromatogram profile.

    PubMed

    Escuder-Gilabert, L; Ruiz-Roch, D; Villanueva-Camañas, R M; Medina-Hernández, M J; Sagrado, S

    2004-03-12

    In the present paper, the simultaneous quantification of two analytes showing strongly overlapped chromatographic peaks (alpha = 1.02), under the assumption that both available equipment and training of the laboratory staff are basic, is studied. A pharmaceutical preparation (Mutabase) containing two drugs of similar physicochemical properties (amitriptyline and perphenazine) is selected as case of study. The assays are carried out under realistic working conditions (i.e. routine testing laboratories). Uncertainty considerations are introduced in the study. A partial least squares model is directly applied to the chromatographic data (with no previous signal transformation) to perform quality control of the pharmaceutical formulation. Under the adequate protocol, the relative error in prediction of analytes is within the tolerances found in the pharmacopeia (10%). For spiked samples simulating formulation mistakes, the errors found have the same magnitude and sign to those provoked.

  11. Simultaneous quantitative analysis of isobars by tandem mass spectrometry from unresolved chromatographic peaks.

    PubMed

    Kushnir, Mark M; Rockwood, Alan L; Nelson, Gordon J

    2004-05-01

    A method was developed for the simultaneous quantitation of isobars from unresolved chromatographic peaks. The method is based on differences in branching ratios of ion abundances in their tandem mass spectra and an assumption that the product ion mass spectra of a mixture can be considered as a linear combination of the spectra of individual constituents. We present analytical equations and a matrix-based approach for deconvoluting the concentration of individual components from the total peak intensity for two and three isobars and also a matrix-based generalization to any number of compounds. The feasibility of the simultaneous analysis of mixtures containing two compounds was assessed. The approach was evaluated for the analysis of structural isomers of methylmalonic and succinic acids in human plasma and urine samples for a group of 270 samples. The linear regression equation, standard error and correlation coefficient for the agreement with a traditional method utilizing chromatographic separation of the isomers were y = 0.999x - 0.005, 0.024 micro mol l(-1), and 0.985, respectively. The utility of a spectral contrast angle as a predictor of analysis feasibility was evaluated.

  12. Practical method for the definition of chromatographic peak parameters in preparative liquid chromatography.

    PubMed

    Jin, Gaowa; Guo, Zhimou; Xiao, Yuansheng; Yan, Jingyu; Dong, Xuefang; Shen, Aijin; Wang, Chaoran; Liang, Xinmiao

    2016-10-01

    A practical method was established for the definition of chromatographic parameters in preparative liquid chromatography. The parameters contained both the peak broadening level under different amounts of sample loading and the concentration distribution of the target compound in the elution. The parameters of the peak broadening level were defined and expressed as a matrix, which consisted of sample loading, the forward broadening and the backward broadening levels. The concentration distribution of the target compound was described by the heat map of the elution profile. The most suitable stationary phase should exhibit the narrower peak broadening and it was best to broaden to both sides to compare to the peak under analytical conditions. Besides, the concentration distribution of the target compounds should be focused on the middle of the elution. The guiding principles were validated by purification of amitriptyline from the mixture of desipramine and amitriptyline. On the selected column, when the content of the impurity desipramine was lower than 0.1%, the recovery of target compound was much higher than the other columns even when the sample loading was as high as 8.03 mg/cm(3) . The parameters and methods could be used for the evaluation and selection of stationary phases in preparative chromatography.

  13. Peak distortion in the column liquid chromatographic determination of omeprazole dissolved in borax buffer.

    PubMed

    Arvidsson, T; Collijn, E; Tivert, A M; Rosén, L

    1991-11-22

    Injection of a sample containing omeprazole dissolved in borax buffer (pH 9.2) into a reversed-phase liquid chromatographic system consisting of a mixture of acetonitrile and phosphate buffer (pH 7.6) as the mobile phase and a C18 surface-modified silica as the solid phase resulted under special conditions in split peaks of omeprazole. The degree of peak split and the retention time of omeprazole varied with the concentration of borax in the sample solution and the ionic strength of the mobile phase buffer as well as with the column used. Borax is eluted from the column in a broad zone starting from the void volume of the column. The retention is probably due to the presence of polyborate ions. The size of the zone varies with the concentration of borax in the sample injected. In the borax zone the pH is increased compared with the pH of the mobile phase, and when omeprazole (a weak acid) is co-eluting in the borax zone its retention is affected. In the front part and in the back part of the borax zone, pH gradients are formed, and these gradients can induce the peak splitting. When the dissolving medium is changed to a phosphate buffer or an ammonium buffer at pH 9 no peak distortion of omeprazole is observed.

  14. Experimental proof of a chromatographic paradox: are the injected molecules in the peak?

    PubMed

    Samuelsson, Jörgen; Forssén, Patrik; Stefansson, Morgan; Fornstedt, Torgny

    2004-02-15

    Forty years ago Helfferich and Peterson published an article in Science regarding a "paradoxical" behavior in nonlinear chromatography (Helfferich, F.; Peterson, D. L. Science 1963, 142, 661-662). They theoretically predicted that when an excess of sample molecules is injected into a chromatographic column that is equilibrated with a constant stream of identical molecules, the observed peak will not contain the injected molecules. Instead the observed peak will only contain molecules from the stream whereas the injected molecules will exit the column in a slower moving, "invisible" peak. They considered it paradoxical that a single injection in a single-component system could cause the successive elution of two peaks (Helfferich, F. J. Chem. Educ. 1964, 41, 410-413). In this study, the paradox is experimentally proven for the first time. Two different strategies were employed: (i) a radiochemical approach and (ii) a method based on the use of two enantiomers in a nonchiral separation system. The experiments were compared with computer simulations.

  15. Multivariate curve resolution based chromatographic peak alignment combined with parallel factor analysis to exploit second-order advantage in complex chromatographic measurements.

    PubMed

    Parastar, Hadi; Akvan, Nadia

    2014-03-13

    In the present contribution, a new combination of multivariate curve resolution-correlation optimized warping (MCR-COW) with trilinear parallel factor analysis (PARAFAC) is developed to exploit second-order advantage in complex chromatographic measurements. In MCR-COW, the complexity of the chromatographic data is reduced by arranging the data in a column-wise augmented matrix, analyzing using MCR bilinear model and aligning the resolved elution profiles using COW in a component-wise manner. The aligned chromatographic data is then decomposed using trilinear model of PARAFAC in order to exploit pure chromatographic and spectroscopic information. The performance of this strategy is evaluated using simulated and real high-performance liquid chromatography-diode array detection (HPLC-DAD) datasets. The obtained results showed that the MCR-COW can efficiently correct elution time shifts of target compounds that are completely overlapped by coeluted interferences in complex chromatographic data. In addition, the PARAFAC analysis of aligned chromatographic data has the advantage of unique decomposition of overlapped chromatographic peaks to identify and quantify the target compounds in the presence of interferences. Finally, to confirm the reliability of the proposed strategy, the performance of the MCR-COW-PARAFAC is compared with the frequently used methods of PARAFAC, COW-PARAFAC, multivariate curve resolution-alternating least squares (MCR-ALS), and MCR-COW-MCR. In general, in most of the cases the MCR-COW-PARAFAC showed an improvement in terms of lack of fit (LOF), relative error (RE) and spectral correlation coefficients in comparison to the PARAFAC, COW-PARAFAC, MCR-ALS and MCR-COW-MCR results.

  16. Theoretical evaluation of peak capacity improvements by use of liquid chromatography combined with drift tube ion mobility-mass spectrometry.

    PubMed

    Causon, Tim J; Hann, Stephan

    2015-10-16

    In the domain of liquid phase separations, the quality of separation obtainable is most readily gauged by consideration of classical chromatographic peak capacity theory. Column-based multidimensional strategies for liquid chromatography remain the most attractive and practical route for increasing the number of spatially resolved components in order to reduce stress on necessary mass spectrometric detection. However, the stress placed on a chromatographic separation step as a second dimension in a comprehensive online methodology (i.e. online LC×LC) is rather high. As an alternative to online LC×LC combinations, coupling of HPLC with ion mobility spectrometry hyphenated to mass spectrometry (IMS-MS) has emerged as an attractive approach to permit comprehensive sampling of first dimension chromatographic peaks and subsequent introduction to an orthogonal IMS separation prior to measurement of ions by a mass spectrometer. In the present work, utilization of classical peak capacity and ion mobility theory allows theoretical assessment of the potential of two- (LC×IMS-MS) or even three-dimensional (LC×LC×IMS-MS) experimental setups to enhance peak capacity and, therefore, the number of correctly annotated features within the framework of complex, non-targeted analysis problems frequently addressed using HPLC-MS strategies. Theoretical calculations indicate that newly-available drift tube IMS-MS instrumentation can yield peak capacities of between 10 and 40 using nitrogen drift gas for typical non-targeted metabolomic, lipidomic and proteomic applications according to the expected reduced mobilities of components in the respective samples. Theoretically, this approach can significantly improve the overall peak capacity of conventional HPLC-(MS) methodologies to in excess of 10(4) depending upon the column length and gradient time employed. A more elaborate combination of LC×LC×IMS-MS would improve the ion suppression limitation and possibly allow access to

  17. Assessment of peak power and short-term work capacity.

    PubMed

    MacIntosh, Brian R; Rishaug, Peter; Svedahl, Krista

    2003-02-01

    The purpose of this study was to evaluate conditions for conducting a 30 s Wingate test such as load selection, and the method of starting the test (stationary or flying start). Nine male and four female athletes volunteered to be tested on four laboratory visits. Tests were performed on a modified Monark cycle ergometer (Varberg, Sweden) equipped with force transducers on the friction belt and an optical encoder for velocity measurement. Power was calculated with the moment of inertia (I) of the flywheel taken into consideration. One laboratory visit was used to determine individualized optimal resistance conditions. The other three visits were for performance of one of three Wingate tests: a flying start with 0.834 N x kg(-1) [85 g x kg(-1) body weight (BW)] resistance (FLY-0.8); a stationary start with 0.834 N x kg(-1) BW resistance (ST-0.8), or a stationary start with optimal resistance (ST-OPT). FLY-0.8 gave a lower (P<0.05) value for short-term work capacity [19,986 (827) J] than either ST-OPT [23,014 (1,167) J] or ST-0.8 [22,321 (1075) J]. Peak power output per pedal revolution was lower ( P<0.005) for FLY-0.8 [833 (40) W] than for either ST-0.8 [974 (57) W] or ST-OPT [989 (61) W]. The results of this study demonstrate that higher values for peak power and short-term work capacity are obtained with a test from a stationary start. It is apparently not necessary to use an individualized optimal resistance when I is considered in a Wingate test initiated from a standstill.

  18. Tailing of chromatographic peaks in GC-MS caused by interaction of halogenated solvents with the ion source.

    PubMed

    Brocks, Jochen J; Hope, Janet M

    2014-07-01

    The injection of analytes into a gas chromatography-mass spectrometry (GC-MS) system using dichloromethane (DCM) as solvent led to gradual deterioration of chromatographic signals, with significant tailing and loss of sensitivity for C17+ hydrocarbons. The injector, gas chromatograph and transfer line were excluded as causes. Normal peak shape could only be restored by the insertion of a cleaned MS ion source. To elucidate potential surficial contaminants, the ion source was heated from 260 to 320°C, leading to the release of increasing concentrations of ferrous chloride [FeCl2(g)]. The ferrous chloride probably formed through the decomposition of DCM on metal surfaces in the ion source. We posit that the tailing was caused by the adsorption of analytes to sub-µm layers of FeCl2 at crystal defect sites in the metal, followed by the slow release of molecules back into the gas phase. There are at least two other cases in the literature in which tailing is specifically associated with the use of halogenated solvents. However, it is possible that the problem is relatively common, albeit rarely diagnosed and reported. The tailing of chromatographic peaks caused by the formation of ferrous chloride in the mass spectrometer can be diagnosed by scanning the MS background signal for the diagnostic isotopic pattern of FeCl2(+). The problem is easily solved by cleaning the MS ion source and avoiding halogenated solvents.

  19. Modeling of the total antioxidant capacity of rooibos (Aspalathus linearis) tea infusions from chromatographic fingerprints and identification of potential antioxidant markers.

    PubMed

    Orzel, Joanna; Daszykowski, Michal; Kazura, Malgorzata; de Beer, Dalene; Joubert, Elizabeth; Schulze, Alexandra E; Beelders, Theresa; de Villiers, André; Malherbe, Christiaan J; Walczak, Beata

    2014-10-31

    Models to predict the total antioxidant capacity (TAC) of rooibos tea infusions from their chromatographic fingerprints and peak table data (content of individual phenolic compounds), obtained using HPLC with diode array detection, were developed in order to identify potential antioxidant markers. Peak table data included the content of 12 compounds, namely phenylpyruvic acid-2-O-glucoside, aspalathin, nothofagin, isoorientin, orientin, ferulic acid, quercetin-3-O-robinobioside, vitexin, hyperoside, rutin, isovitexin and isoquercitrin. The TAC values, measured using the oxygen radical absorbance capacity (ORAC) and DPPH radical scavenging assays, could be predicted from the peak table data or the chromatographic fingerprints (prediction errors 9-12%) using partial least squares (PLS) regression. Prediction models created from samples of only two production years could additionally be used to predict the TAC of samples from another production year (prediction errors<13%) indicating the robustness of the models in a quality control environment. Furthermore, the uninformative variable elimination (UVE)-PLS method was used to identify potential antioxidant markers for rooibos infusions. All individual phenolic compounds that were quantified were selected as informative variables, except vitexin, while UVE-PLS models developed from chromatographic fingerprints indicated additional antioxidant markers, namely (S)-eriodictyol-6-C-glucoside, (R)-eriodictyol-6-C-glucoside, aspalalinin and two unidentified compounds. The potential antioxidant markers should be validated prior to use in quality control of rooibos tea.

  20. Peak capacity, peak-capacity production rate, and boiling point resolution for temperature-programmed GC with very high programming rates

    PubMed

    Grall; Leonard; Sacks

    2000-02-01

    Recent advances in column heating technology have made possible very fast linear temperature programming for high-speed gas chromatography. A fused-silica capillary column is contained in a tubular metal jacket, which is resistively heated by a precision power supply. With very rapid column heating, the rate of peak-capacity production is significantly enhanced, but the total peak capacity and the boiling-point resolution (minimum boiling-point difference required for the separation of two nonpolar compounds on a nonpolar column) are reduced relative to more conventional heating rates used with convection-oven instruments. As temperature-programming rates increase, elution temperatures also increase with the result that retention may become insignificant prior to elution. This results in inefficient utilization of the down-stream end of the column and causes a loss in the rate of peak-capacity production. The rate of peak-capacity production is increased by the use of shorter columns and higher carrier gas velocities. With high programming rates (100-600 degrees C/min), column lengths of 6-12 m and average linear carrier gas velocities in the 100-150 cm/s range are satisfactory. In this study, the rate of peak-capacity production, the total peak capacity, and the boiling point resolution are determined for C10-C28 n-alkanes using 6-18 m long columns, 50-200 cm/s average carrier gas velocities, and 60-600 degrees C/min programming rates. It was found that with a 6-meter-long, 0.25-mm i.d. column programmed at a rate of 600 degrees C/min, a maximum peak-capacity production rate of 6.1 peaks/s was obtained. A total peak capacity of about 75 peaks was produced in a 37-s long separation spanning a boiling-point range from n-C10 (174 degrees C) to n-C28 (432 degrees C).

  1. Loading capacity and chromatographic behavior of a porous graphitic carbon column for polychlorinated biphenyls

    USGS Publications Warehouse

    Echols, K.R.; Gale, R.W.; Feltz, K.; O'Laughlin, J.; Tillitt, D.E.; Schwartz, T.R.

    1998-01-01

    A porous graphitic carbon column (Hypercarb) was used for the fractionation of polychlorinated biphenyls (PCBs) into classes of 2-4 ortho chlorines, 1 ortho chlorine and 0 ortho chlorine congeners. A method was developed that combined the fractionation of PCBs, polychlorinated dibenzo- p-dioxins and dibenzofurans in a variety of biotic environmental samples. Many of these samples have high concentrations of PCBs which cause fractionation problems as adsorption sites on the graphitic surface are occupied. The loading capacity of the column for PCBs was determined by injecting up to 1 mg of total PCBs and monitoring changes in chromatographic behavior of tetra-/di-ortho, mono-ortho and non-ortho substituted PCBs. Effective loading capacities were 1 mg for tetra-/di-ortho PCBs, but only 3- 5 ??g for non-ortho PCBs and about 2 ??g for mono-ortho PCBs. Loading capacity of the PGC column for environmental fish and avian egg samples was determined to depend on the mono-ortho and non-ortho PCB levels found in these samples.

  2. Improving the binding capacities of protein A chromatographic materials by means of ligand polymerization.

    PubMed

    Freiherr von Roman, Matthias; Berensmeier, Sonja

    2014-06-20

    Protein A chromatography is one of the most important techniques used in the purification of monoclonal antibodies. Due to the low dynamic binding capacity of protein A chromatographic materials compared to other stationary phases, protein A chromatography is often discussed to be the bottleneck among current purification processes. Several approaches were tested within this study in order to maximize IgG binding capacities of current acrylamido-based based resins. Genetic engineering techniques were used in order to polymerize one of the IgG binding domains (B-domain) of protein A from Staphylococcus aureus (SpA) to achieve ligands with an increased length. The solution-binding ratio and the total size of ligand-antibody complexes were used to characterize the interaction potential of novel ligands, revealing a relatively linear dependency between the number of binding domains upon the amount of bound antibody molecules. This relationship was also valid up to a ligand which was comprised of 8 B-domains after attaching them onto acrylamido-based based stationary phases using epoxy coupling techniques. Equilibrium binding capacities of more than 80mghIgGmL(-1) were achieved using the B8 ligand. Furthermore, static binding capacities, especially for smaller ligands comprised of fewer B-domains, were improved up to 87mghIgGmL(-1) using site-specific coupling chemistry, which is an improvement of more than 20% compared to commercially available materials. In order to evaluate pore exclusion effects due to the use of prolonged affinity ligands, prepared materials were characterized regarding their effective intraparticle porosity and breakthrough capacity.

  3. Characterization of peak capacity of microbore liquid chromatography columns using gradient kinetic plots.

    PubMed

    Hetzel, Terence; Blaesing, Christina; Jaeger, Martin; Teutenberg, Thorsten; Schmidt, Torsten C

    2017-02-17

    The performance of micro-liquid chromatography columns with an inner diameter of 0.3mm was investigated on a dedicated micro-LC system for gradient elution. Core-shell as well as fully porous particle packed columns were compared on the basis of peak capacity and gradient kinetic plot limits. The results for peak capacity showed the superior performance of columns packed with sub-2μm fully porous particles compared to 3.0μm fully porous and 2.7μm core-shell particles within a range of different gradient time to column void time ratios. For ultra-fast chromatography a maximum peak capacity of 16 can be obtained using a 30s gradient for the sub-2μm fully porous particle packed column. A maximum peak capacity of 121 can be achieved using a 5min gradient. In addition, the influence of an alternative detector cell on the basis of optical waveguide technology and contributing less to system variance was investigated showing an increased peak capacity for all applied gradient time/column void time ratios. Finally, the influence of pressure was evaluated indicating increased peak capacity for maximum performance whereas a limited benefit for ultra-fast chromatography with gradient times below 30s was observed.

  4. Spectral correlation of high-performance liquid chromatography-diode array detection data from two independent chromatographic runs peak tracking in pharmaceutical impurity profiling.

    PubMed

    Li, Wei; Hu, Chang-qin

    2008-05-09

    A novel qualitative analytical method for peak tracking in impurity profiling control by the correlation of spectra was established. Two-dimensional (2D) standard spectrochromatographic data produced by high-performance liquid chromatography with diode array detection (HPLC-DAD) were compared with sample data to develop two-dimensional chromatographic spectral correlative maps. Taking full advantage of separation efficiency of HPLC and spectral specificity of the analytes, the method was successfully used to recognize impurities in quinolone antibacterials, when in combination with relative retention times (RRTs). For the comparison of spectra was expanded to three-dimensional space, simultaneous identification of the chromatographic peaks can be obtained rapidly without preparation and injection of a reference solution, even when the mobile phase changed or the peaks of multi-component samples overlapped.

  5. A Simple and Accurate Equation for Peak Capacity Estimation in Two Dimensional Liquid Chromatography

    PubMed Central

    Li, Xiaoping; Stoll, Dwight R.; Carr, Peter W.

    2009-01-01

    Two dimensional liquid chromatography (2DLC) is a very powerful way to greatly increase the resolving power and overall peak capacity of liquid chromatography. The traditional “product rule” for peak capacity usually overestimates the true resolving power due to neglect of the often quite severe under-sampling effect and thus provides poor guidance for optimizing the separation and biases comparisons to optimized one dimensional gradient liquid chromatography. Here we derive a simple yet accurate equation for the effective two dimensional peak capacity that incorporates a correction for under-sampling of the first dimension. The results show that not only is the speed of the second dimension separation important for reducing the overall analysis time, but it plays a vital role in determining the overall peak capacity when the first dimension is under-sampled. A surprising subsidiary finding is that for relatively short 2DLC separations (much less than a couple of hours), the first dimension peak capacity is far less important than is commonly believed and need not be highly optimized, for example through use of long columns or very small particles. PMID:19053226

  6. Impacts of Climate Change on Electric Transmission Capacity and Peak Electricity Load in the United States

    NASA Astrophysics Data System (ADS)

    Chester, M.; Bartos, M. D.; Eisenberg, D. A.; Gorman, B.; Johnson, N.

    2015-12-01

    Climate change may hinder future electricity reliability by reducing electric transmission capacity while simultaneously increasing electricity demand. This study estimates potential climate impacts to electric transmission capacity and peak electricity load in the United States. Electric power cables suffer decreased transmission capacity as they get hotter; similarly, during the summer peak period, electricity demand typically increases with hotter ambient air temperatures due to increased cooling loads. As atmospheric carbon concentrations increase, higher air temperatures may strain power infrastructure by reducing transmission capacity and increasing peak electricity loads. Taken together, these coincident impacts may have unpredictable consequences for electric power reliability. We estimate the effects of climate change on both the rated capacity of transmission infrastructure and expected electricity demand for 120 electrical utilities across the United States. We estimate climate-attributable capacity reductions to transmission lines by constructing thermal models of representative conductors, then forcing these models with downscaled CMIP5 temperature projections to determine the relative change in rated ampacity over the twenty-first century. Next, we assess the impact of climate change on electricity demand by using historical relationships between ambient temperature and utility-scale summertime peak load to estimate the extent to which climate change will incur additional peak load increases. We use downscaled temperature projections from 11 CMIP5 GCM models under 3 atmospheric carbon scenarios. We find that by mid-century (2040-2060), climate change may reduce average summertime transmission capacity by 4-6% relative to the 1990-2010 reference period. At the same time, peak summertime loads may rise by roughly 2-12% on average due to increases in daily maximum air temperature. In the absence of energy efficiency gains, demand-side management programs

  7. Evaluation of injection methods for fast, high peak capacity separations with low thermal mass gas chromatography.

    PubMed

    Fitz, Brian D; Mannion, Brandyn C; To, Khang; Hoac, Trinh; Synovec, Robert E

    2015-05-01

    Low thermal mass gas chromatography (LTM-GC) was evaluated for rapid, high peak capacity separations with three injection methods: liquid, headspace solid phase micro-extraction (HS-SPME), and direct vapor. An Agilent LTM equipped with a short microbore capillary column was operated at a column heating rate of 250 °C/min to produce a 60s separation. Two sets of experiments were conducted in parallel to characterize the instrumental platform. First, the three injection methods were performed in conjunction with in-house built high-speed cryo-focusing injection (HSCFI) to cryogenically trap and re-inject the analytes onto the LTM-GC column in a narrower band. Next, the three injection methods were performed natively with LTM-GC. Using HSCFI, the peak capacity of a separation of 50 nl of a 73 component liquid test mixture was 270, which was 23% higher than without HSCFI. Similar peak capacity gains were obtained when using the HSCFI with HS-SPME (25%), and even greater with vapor injection (56%). For the 100 μl vapor sample injected without HSCFI, the preconcentration factor, defined as the ratio of the maximum concentration of the detected analyte peak relative to the analyte concentration injected with the syringe, was determined to be 11 for the earliest eluting peak (most volatile analyte). In contrast, the preconcentration factor for the earliest eluting peak using HSCFI was 103. Therefore, LTM-GC is demonstrated to natively provide in situ analyte trapping, although not to as great an extent as with HSCFI. We also report the use of LTM-GC applied with time-of-flight mass spectrometry (TOFMS) detection for rapid, high peak capacity separations from SPME sampled banana peel headspace.

  8. Wingate Anaerobic Test peak power and anaerobic capacity classifications for men and women intercollegiate athletes.

    PubMed

    Zupan, Michael F; Arata, Alan W; Dawson, Letitia H; Wile, Alfred L; Payn, Tamara L; Hannon, Megan E

    2009-12-01

    The Wingate Anaerobic Test (WAnT) has been established as an effective tool in measuring both muscular power and anaerobic capacity in a 30-second time period; however, there are no published normative tables by which to compare WAnT performance in men and women intercollegiate athletics. The purpose of this study was to develop a classification system for anaerobic peak power and anaerobic capacity for men and women National Collegiate Athletic Association (NCAA) Division I college athletes using the WAnT. A total of 1,585 (1,374 men and 211 women) tests were conducted on athletes ranging from the ages of 18 to 25 years using the WAnT. Absolute and relative peak power and anaerobic capacity data were recorded. One-half standard deviations were used to set up a 7-tier classification system (poor to elite) for these assessments. These classifications can be used by athletes, coaches, and practitioners to evaluate anaerobic peak power and anaerobic capacity in their athletes.

  9. The Unified Parkinson's Disease Rating Scale as a predictor of peak aerobic capacity and ambulatory function.

    PubMed

    Ivey, Frederick M; Katzel, Leslie I; Sorkin, John D; Macko, Richard F; Shulman, Lisa M

    2012-01-01

    The Unified Parkinson's Disease Rating Scale (UPDRS) is a widely applied index of disease severity. Our objective was to assess the utility of UPDRS for predicting peak aerobic capacity (VO2 peak) and ambulatory function. Participants (n = 70) underwent evaluation for UPDRS (Total and Motor ratings), VO2 peak, 6-minute walk distance (6MW), and 30-foot self-selected walking speed (SSWS). Using regression, we determined the extent to which the Total and Motor UPDRS scores predicted each functional capacity measure after adjusting for age and sex. We also tested whether adding the Hoehn and Yahr scale (H-Y) to the model changed predictive power of the UPDRS. Adjusted for age and sex, both the Total UPDRS and Motor UPDRS subscale failed to predict VO2 peak. The Total UPDRS did weakly predict 6MW and SSWS (both p < 0.05), but the Motor UPDRS subscale did not predict these ambulatory function tests. After adding H-Y to the model, Total UPDRS was no longer an independent predictor of 6MW but remained a predictor of SSWS. We conclude that Total and Motor UPDRS rating scales do not predict VO2 peak, but that a weak relationship exists between Total UPDRS and measures of ambulatory function.

  10. Wingate Anaerobic Test Peak Power and Anaerobic Capacity Classification for Men and Women Intercollegiate Athletes

    DTIC Science & Technology

    2009-12-01

    including football, sprinting, soccer, baseball, lacrosse, and gymnastics - use anaerobic metabolism extensively during competition. This study...1 . 3 62j + 7.7 167.1 + 7 .9 Tennis, track, soccer, and gymnastics urements allow a coach to observe individual improvements; however, it is...require short bursts of peak power and a high anaerobic capacity during competition to include lacrosse, gymnastics , sprint cycling, football, baseball

  11. Aerobic capacity and peak power output of elite quadriplegic games players

    PubMed Central

    Goosey‐Tolfrey, V; Castle, P; Webborn, N

    2006-01-01

    Background Participation in wheelchair sports such as tennis and rugby enables people with quadriplegia to compete both individually and as a team at the highest level. Both sports are dominated by frequent, intermittent, short term power demands superimposed on a background of aerobic activity. Objective To gain physiological profiles of highly trained British quadriplegic athletes, and to examine the relation between aerobic and sprint capacity. Methods Eight male quadriplegic athletes performed an arm crank exercise using an ergometer fitted with a Schoberer Rad Messtechnik (SRM) powermeter. The sprint test consisted of three maximum‐effort sprints of five seconds duration against a resistance of 2%, 3%, and 4% of body mass. The highest power output obtained was recorded (PPO). Peak oxygen consumption (V̇o2peak), peak heart rate (HRpeak), and maximal power output (POaer) were determined. Results Mean POaer was 67.7 (16.2) W, mean V̇o2peak was 0.96 (0.17) litres/min, and HRpeak was 134 (19) beats/min for the group. There was high variability among subjects. Peak power over the five second sprint for the group was 220 (62) W. There was a significant correlation between V̇o2peak (litres/min) and POaer (W) (r  =  0.74, p<0.05). Conclusions These British quadriplegic athletes have relatively high aerobic fitness when compared with the available literature. Moreover, the anaerobic capacity of these athletes appeared to be relatively high compared with paraplegic participants. PMID:16611721

  12. Peak Frequency in the Theta and Alpha Bands Correlates with Human Working Memory Capacity

    PubMed Central

    Moran, Rosalyn J.; Campo, Pablo; Maestu, Fernando; Reilly, Richard B.; Dolan, Raymond J.; Strange, Bryan A.

    2010-01-01

    Theta oscillations in the local field potential of neural ensembles are considered key mediators of human working memory. Theoretical accounts arising from animal hippocampal recordings propose that the phase of theta oscillations serves to instantiate sequential neuronal firing to form discrete representations of items held online. Human evidence of phase relationships in visual working memory has enhanced this theory, implicating long theta cycles in supporting greater memory capacity. Here we use human magnetoencephalographic recordings to examine a novel, alternative principle of theta functionality. The principle we hypothesize is derived from information theory and predicts that rather than long (low frequency) theta cycles, short (high frequency) theta cycles are best suited to support high information capacity. From oscillatory activity recorded during the maintenance period of a visual working memory task we show that a network of brain regions displays an increase in peak 4–12 Hz frequency with increasing memory load. Source localization techniques reveal that this network comprises bilateral prefrontal and right parietal cortices. Further, the peak of oscillation along this theta–alpha frequency axis is significantly higher in high capacity individuals compared to low capacity individuals. Importantly while we observe the adherence of cortical neuronal oscillations to our novel principle of theta functioning, we also observe the traditional inverse effect of low frequency theta maintaining high loads, where critically this was located in medial temporal regions suggesting parallel, dissociable hippocampal-centric, and prefrontal-centric theta mechanisms. PMID:21206531

  13. Maintained peak leg and pulmonary VO2 despite substantial reduction in muscle mitochondrial capacity.

    PubMed

    Boushel, R; Gnaiger, E; Larsen, F J; Helge, J W; González-Alonso, J; Ara, I; Munch-Andersen, T; van Hall, G; Søndergaard, H; Saltin, B; Calbet, J A L

    2015-12-01

    We recently reported the circulatory and muscle oxidative capacities of the arm after prolonged low-intensity skiing in the arctic (Boushel et al., 2014). In the present study, leg VO2 was measured by the Fick method during leg cycling while muscle mitochondrial capacity was examined on a biopsy of the vastus lateralis in healthy volunteers (7 male, 2 female) before and after 42 days of skiing at 60% HR max. Peak pulmonary VO2 (3.52 ± 0.18 L.min(-1) pre vs 3.52 ± 0.19 post) and VO2 across the leg (2.8 ± 0.4L.min(-1) pre vs 3.0 ± 0.2 post) were unchanged after the ski journey. Peak leg O2 delivery (3.6 ± 0.2 L.min(-1) pre vs 3.8 ± 0.4 post), O2 extraction (82 ± 1% pre vs 83 ± 1 post), and muscle capillaries per mm(2) (576 ± 17 pre vs 612 ± 28 post) were also unchanged; however, leg muscle mitochondrial OXPHOS capacity was reduced (90 ± 3 pmol.sec(-1) .mg(-1) pre vs 70 ± 2 post, P < 0.05) as was citrate synthase activity (40 ± 3 μmol.min(-1) .g(-1) pre vs 34 ± 3 vs P < 0.05). These findings indicate that peak muscle VO2 can be sustained with a substantial reduction in mitochondrial OXPHOS capacity. This is achieved at a similar O2 delivery and a higher relative ADP-stimulated mitochondrial respiration at a higher mitochondrial p50. These findings support the concept that muscle mitochondrial respiration is submaximal at VO2max , and that mitochondrial volume can be downregulated by chronic energy demand.

  14. Half-width plots, a simple tool to predict peak shape, reveal column kinetics and characterise chromatographic columns in liquid chromatography: state of the art and new results.

    PubMed

    Baeza-Baeza, J J; Ruiz-Ángel, M J; García-Álvarez-Coque, M C; Carda-Broch, S

    2013-11-01

    Peak profiles in chromatography are characterised by their height, position, width and asymmetry; the two latter depend on the values of the left and right peak half-widths. Simple correlations have been found between the peak half-widths and the retention times. The representation of such correlations has been called half-width plots. For isocratic elution, the plots are parabolic, although often, the parabolas can be approximated to straight-lines. The plots can be obtained with the half-widths/retention time data for a set of solutes experiencing the same kinetics, eluted with a mobile phase at fixed or varying composition. When the analysed solutes experience different resistance to mass transfer, the plots will be solute dependent, and should be obtained with the data for each solute eluted with mobile phases at varying composition. The half-width plots approach is a simple tool that facilitates the prediction of peak shape (width and asymmetry) with optimisation purposes, reveal the interaction kinetics of solutes in different columns, and characterise chromatographic columns. This work shows half-width plots for different situations in isocratic elution, including the use of different flows, the effect of temperature, the modification of the stationary phase surface by an additive, the existence of specific interactions within the column, and the comparison of columns. The adaptation to gradient elution is also described. Previous knowledge on half-width plots is structured and analysed, to which new results are added.

  15. Efficient fabrication of high-capacity immobilized metal ion affinity chromatographic media: The role of the dextran-grafting process and its manipulation.

    PubMed

    Zhao, Lan; Zhang, Jingfei; Huang, Yongdong; Li, Qiang; Zhang, Rongyue; Zhu, Kai; Suo, Jia; Su, Zhiguo; Zhang, Zhigang; Ma, Guanghui

    2016-03-01

    Novel high-capacity Ni(2+) immobilized metal ion affinity chromatographic media were prepared through the dextran-grafting process. Dextran was grafted to an allyl-activated agarose-based matrix followed by functionalization for the immobilized metal ion affinity chromatographic media. With elaborate regulation of the allylation degree, dextran was completely or partly grafted to agarose microspheres, namely, completely dextran-grafted agarose microspheres and partly dextran-grafted ones, respectively. Confocal laser scanning microscope results demonstrated that a good adjustment of dextran-grafting degree was achieved, and dextran was distributed uniformly in whole completely dextran-grafted microspheres, while just distributed around the outside of the partly dextran-grafted ones. Flow hydrodynamic properties were improved greatly after the dextran-grafting process, and the flow velocity increased by about 30% compared with that of a commercial chromatographic medium (Ni Sepharose FF). A significant improvement of protein binding performance was also achieved by the dextran-grafting process, and partly dextran-grafted Ni(2+) chelating medium had a maximum binding capacity for His-tagged lactate dehydrogenase about 2.5 times higher than that of Ni Sepharose FF. The results indicated that this novel chromatographic medium is promising for applications in high-efficiency and large-scale protein purification.

  16. The impact of sampling time on peak capacity and analysis speed in on-line comprehensive two-dimensional liquid chromatography.

    PubMed

    Potts, Lawrence W; Stoll, Dwight R; Li, Xiaoping; Carr, Peter W

    2010-09-03

    Comprehensive two-dimensional liquid chromatography (2DLC) offers a number of practical advantages over optimized one-dimensional LC in peak capacity and thus in resolving power. The traditional "product rule" for overall peak capacity for a 2DLC system significantly overestimates peak capacity because it neglects under-sampling of the first dimension separation. Here we expand on previous work by more closely examining the effects of the first dimension peak capacity and gradient time, and the second dimension cycle times on the overall peak capacity of the 2DLC system. We also examine the effects of re-equilibration time on under-sampling as measured by the under-sampling factor and the influence of molecular type (peptide vs. small molecule) on peak capacity. We show that in fast 2D separations (less than 1h), the second dimension is more important than the first dimension in determining overall peak capacity and conclude that extreme measures to enhance the first dimension peak capacity are usually unwarranted. We also examine the influence of sample types (small molecules vs. peptides) on second dimension peak capacity and peak capacity production rates, and how the sample type influences optimum second dimension gradient and re-equilibration times.

  17. The Impact of Sampling Time on Peak Capacity and Analysis Speed in On-line Comprehensive Two-Dimensional Liquid Chromatography

    PubMed Central

    Potts, Lawrence W.; Stoll, Dwight R.; Li, Xiaoping; Carr, Peter W.

    2010-01-01

    Comprehensive two-dimensional liquid chromatography (2DLC) offers a number of practical advantages over optimized one-dimensional LC in peak capacity and thus in resolving power. The traditional “product rule” for overall peak capacity for a 2DLC system significantly overestimates peak capacity because it neglects under-sampling of the first dimension separation. Here we expand on previous work by more closely examining the effects of the first dimension peak capacity and gradient time, and the second dimension cycle times on the overall peak capacity of the 2DLC system. We also examine the effects of re-equilibration time on under-sampling as measured by the under-sampling factor and the influence of molecular type (peptide vs. small molecule) on peak capacity. We show that in fast 2D separations (less than one hour), the second dimension is more important than the first dimension in determining overall peak capacity and conclude that extreme measures to enhance the first dimension peak capacity are usually unwarranted. We also examine the influence of sample types (small molecules vs. peptides) on second dimension peak capacity and peak capacity production rates, and how the sample type influences optimum second dimension gradient and re-equilibration times. PMID:20673902

  18. Relative Economic Merits of Storage and Combustion Turbines for Meeting Peak Capacity Requirements under Increased Penetration of Solar Photovoltaics

    SciTech Connect

    Denholm, Paul; Diakov, Victor; Margolis, Robert

    2015-09-01

    Batteries with several hours of capacity provide an alternative to combustion turbines for meeting peak capacity requirements. Even when compared to state-of-the-art highly flexible combustion turbines, batteries can provide a greater operational value, which is reflected in a lower system-wide production cost. By shifting load and providing operating reserves, batteries can reduce the cost of operating the power system to a traditional electric utility. This added value means that, depending on battery life, batteries can have a higher cost than a combustion turbine of equal capacity and still produce a system with equal or lower overall life-cycle cost. For a utility considering investing in new capacity, the cost premium for batteries is highly sensitive to a variety of factors, including lifetime, natural gas costs, PV penetration, and grid generation mix. In addition, as PV penetration increases, the net electricity demand profile changes, which may reduce the amount of battery energy capacity needed to reliably meet peak demand.

  19. Bedrest-induced peak VO2 reduction associated with age, gender, and aerobic capacity

    NASA Technical Reports Server (NTRS)

    Convertino, V. A.; Goldwater, D. J.; Sandler, H.

    1986-01-01

    A study measuring the peak oxygen uptake (V02), heart rate (HR), and exercise tolerance time of 15 men of 55 + or - 2 yr and 17 women of 55 + or - 1 yr after 10 days of continuous bed rest (BR) is presented. The experimental conditions and procedures are described. Following BR a decrease in peak VO2 of 8.4 percent in men and 6.8 percent in women, a reduction in exercise tolerance time by 8.1 percent in men and 7.3 percent in women, and an increse in HR of 4.4 percent and 1.3 percent for men and women, respectively, are observed. These data are compared with data from Convertino et al. (1977) for men 21 + or - 1 yr and women 28 + or - 2yr. It is concluded that BR-induced aerobic deconditioning is independent of age and sex, since the relative decrease in peak V02 in the older and younger subjects and men and women are similar.

  20. Load controller and method to enhance effective capacity of a photovoltaic power supply using a dynamically determined expected peak loading

    DOEpatents

    Perez, Richard

    2005-05-03

    A load controller and method are provided for maximizing effective capacity of a non-controllable, renewable power supply coupled to a variable electrical load also coupled to a conventional power grid. Effective capacity is enhanced by monitoring power output of the renewable supply and loading, and comparing the loading against the power output and a load adjustment threshold determined from an expected peak loading. A value for a load adjustment parameter is calculated by subtracting the renewable supply output and the load adjustment parameter from the current load. This value is then employed to control the variable load in an amount proportional to the value of the load control parameter when the parameter is within a predefined range. By so controlling the load, the effective capacity of the non-controllable, renewable power supply is increased without any attempt at operational feedback control of the renewable supply.

  1. Load controller and method to enhance effective capacity of a photovotaic power supply using a dynamically determined expected peak loading

    DOEpatents

    Perez, Richard

    2003-04-01

    A load controller and method are provided for maximizing effective capacity of a non-controllable, renewable power supply coupled to a variable electrical load also coupled to a conventional power grid. Effective capacity is enhanced by monitoring power output of the renewable supply and loading, and comparing the loading against the power output and a load adjustment threshold determined from an expected peak loading. A value for a load adjustment parameter is calculated by subtracting the renewable supply output and the load adjustment parameter from the current load. This value is then employed to control the variable load in an amount proportional to the value of the load control parameter when the parameter is within a predefined range. By so controlling the load, the effective capacity of the non-controllable, renewable power supply is increased without any attempt at operational feedback control of the renewable supply. The expected peak loading of the variable load can be dynamically determined within a defined time interval with reference to variations in the variable load.

  2. Brain natriuretic peptide predicts forced vital capacity of the lungs, oxygen pulse and peak oxygen consumption in physiological condition.

    PubMed

    Popovic, Dejana; Ostojic, Miodrag C; Popovic, Bojana; Petrovic, Milan; Vujisic-Tesic, Bosiljka; Kocijancic, Aleksandar; Banovic, Marko; Arandjelovic, Aleksandra; Stojiljkovic, Stanimir; Markovic, Vidan; Damjanovic, Svetozar S

    2013-05-01

    Brain natriuretic peptide (NT-pro-BNP) is used as marker of cardiac and pulmonary diseases. However, the predictive value of circulating NT-pro-BNP for cardiac and pulmonary performance is unclear in physiological conditions. Standard echocardiography, tissue Doppler and forced spirometry at rest were used to assess cardiac parameters and forced vital capacity (FVC) in two groups of athletes (16 elite male wrestlers (W), 21 water polo player (WP)), as different stress adaptation models, and 20 sedentary subjects (C) matched for age. Cardiopulmonary test on treadmill (CPET), as acute stress model, was used to measure peak oxygen consumption (peak VO2), maximal heart rate (HRmax) and peak oxygen pulse (peak VO2/HR). NT-pro-BNP was measured by immunoassey sandwich technique 10min before the test - at rest, at the beginning of the test, at maximal effort, at third minute of recovery. FVC was higher in athletes and the highest in W (WP 5.60±0.29 l; W 6.57±1.00 l; C 5.41±0.29 l; p<0.01). Peak VO2 and peak VO2/HR were higher in athletes and the highest in WP. HRmax was not different among groups. In all groups, NT-pro-BNP decreased from rest to the beginning phase, increased in maximal effort and stayed unchanged in recovery. NT-pro-BNP was higher in C than W in all phases; WP had similar values as W and C. On multiple regression analysis, in all three groups together, ΔNT-pro-BNP from rest to the beginning phase independently predicted both peak VO2 and peak VO2/HR (r=0.38, 0.35; B=37.40, 0.19; p=0.007, 0.000, respectively). NT-pro-BNP at rest predicted HRmax (r=-0.32, B=-0.22, p=0.02). Maximal NT-pro-BNP predicted FVC (r=-0.22, B=-0.07, p=0.02). These results show noticeable predictive value of NT-pro-BNP for both cardiac and pulmonary performance in physiological conditions suggesting that NT-pro-BNP could be a common regulatory factor coordinating adaptation of heart and lungs to stress condition.

  3. Separation of intact proteins on γ-ray-induced polymethacrylate monolithic columns: A highly permeable stationary phase with high peak capacity for capillary high-performance liquid chromatography with high-resolution mass spectrometry.

    PubMed

    Simone, Patrizia; Pierri, Giuseppe; Foglia, Patrizia; Gasparrini, Francesca; Mazzoccanti, Giulia; Capriotti, Anna Laura; Ursini, Ornella; Ciogli, Alessia; Laganà, Aldo

    2016-01-01

    Polymethacrylate-based monolithic capillary columns, prepared by γ-radiation-induced polymerization, were used to optimize the experimental conditions (nature of the organic modifiers, the content of trifluoroacetic acid and the column temperature) in the separation of nine standard proteins with different hydrophobicities and a wide range of molecular weights. Because of the excellent permeability of the monolithic columns, an ion-pair reversed-phase capillary liquid chromatography with high-resolution mass spectrometry method has been developed by coupling the column directly to the mass spectrometer without a flow-split and using a standard electrospray interface. Additionally, the high working flow and concomitant high efficiency of these columns allowed us to employ a longer column (up to 50 cm) and achieve a peak capacity value superior to 1000. This work is motivated by the need to develop new materials for high-resolution chromatographic separation that combine chemical stability at elevated temperatures (up to 75°C) and a broad pH range, with a high peak capacity value. The advantage of the γ-ray-induced monolithic column lies in the batch-to-batch reproducibility and long-term high-temperature stability. Their proven high loading capacity, recovery, good selectivity and high permeability, moreover, compared well with that of a commercially available poly(styrene-divinylbenzene) monolithic column, which confirms that such monolithic supports might facilitate analysis in proteomics.

  4. Improving stability of virus-like particles by ion-exchange chromatographic supports with large pore size: advantages of gigaporous media beyond enhanced binding capacity.

    PubMed

    Yu, Mengran; Li, Yan; Zhang, Songping; Li, Xiunan; Yang, Yanli; Chen, Yi; Ma, Guanghui; Su, Zhiguo

    2014-02-28

    Limited binding capacity and low recovery of large size multi-subunits virus-like particles (VLPs) in conventional agarose-gel based chromatographic supports with small pores have long been a bottleneck limiting the large scale purification and application of VLPs. In this study, four anion exchange media including DEAE-Sepharose FF (DEAE-FF), DEAE-Capto, gigaporous DEAE-AP-120nm and DEAE-AP-280nm with average pore diameters of 32nm, 20nm, 120nm and 280nm, respectively, were applied for purification of hepatitis B virus surface antigen (HBsAg) VLPs. Pore size effects of media on the VLPs adsorption equilibrium, adsorption kinetics, dynamic binding capacity (DBC), and recovery were investigated in detail. According to the confocal laser scanning microscopy observation, adsorption of the VLPs in DEAE-FF and DEAE-Capto was mostly confined to a thin shell on the outer surface of the beads, leaving the underlying pore space and the binding sites inaccessibly, while the large pores in gigaporous media enabled the VLPs to access to the interior pore spaces by diffusion transport efficiently. Compared to the most widely used DEAE-FF, gigaporous media DEAE-AP-280nm gained about 12.9 times increase in static adsorption capacity, 8.0 times increase in DBC, and 11.4 times increase in effective pore diffusivity. Beyond increasing the binding capacity and enhancing the mass transfer, the gigaporous structure also significantly improved the stability of the VLPs during intensive adsorption-desorption process by lowing the multi-point interaction between the VLPs and binding sites in the pores. At 2.0mg/mL-media loading quantity, about 85.5% VLPs were correctly self-assembled after the chromatography with DEAE-AP-280nm media; oppositely about 85.2% VLPs lost their normal assembly with DEAE-FF due to irreversible disassembly. Comparative investigation was made to study the purifying performance of these four chromatographic media for actual VLPs purification from recombinant

  5. Influence of peak-broadening and interdetector volume error on size-exclusive chromatographic analysis with dual viscometric-concentration detection using the universal calibration method.

    PubMed

    Netopilík, M

    2001-04-27

    The effect of peak-broadening and error in interdetector volume on the local calibration curve and experimental molecular-mass averages obtained by size-exclusion chromatography (SEC) with dual concentration/viscosity detection, and determination of molecular mass using the universal calibration (UC) method, is theoretically examined using a polymer sample with a molecular-mass distribution (MMD) approximated by the log-normal function. Although peak-broadening is often neglected, its effect on the slope of the local calibration curve and, consequently, on the experimentally obtained values of the weight-to-number average ratio is large. To obtain the right values of these parameters, a numerical correction is usually recommended. While using the UC method, the relationships between the extent of peak broadening, calibration slopes and interdetector volume are complex and can contribute to the occurrence of undiscovered errors. For this reason, an understanding of this problem, using a model, is necessary. The results of the UC method are compared with those obtained using dual-detection with known Mark-Houwink-Kuhn-Sakurada parameters (MHKS method), light-scattering (LS)/concentration detection as well as with the results obtained using conventional calibration. Due to peak-broadening, the slope of a local calibration curve and the weight-to-number average ratio, (Mw/Mn)", obtained using the UC method, increase compared to the theoretical values, whereas they decrease using the MHKS or LS methods. The increase when using the UC method is even larger compared to evaluation using conventional calibration. The effect of the error in interdetector volume on the slopes of local calibrations and the weight-to-number average ratios is opposite in the UC method to that found using the MHKS and LS methods.

  6. Spectrophotometric and chromatographic assessment of contributions of carotenoids and chlorophylls to the total antioxidant capacities of plant foods.

    PubMed

    Sözgen Başkan, Kevser; Tütem, Esma; Özer, Nihat; Apak, Reşat

    2013-11-27

    Carotenoids and chlorophylls are photosynthetic compounds and also efficient antioxidants. This study aims to identify and quantify carotenoids and chlorophylls in some vegetables (carrot, tomato, spinach), to measure the total antioxidant capacity (TAC) of these samples with two spectrophotometric methods, to correlate TAC data with carotenoid structure, and to compare the TAC results with HPLC findings. Separation of the individual antioxidant pigments was achieved on a C30 column using a developed gradient elution program involving methanol-acetonitrile (50:50, v/v) with 0.1% (v/v) triethylamine (TEA) (A) and acetone (B) mobile phases. Total antioxidant capacities of the acetone extracts of studied samples, in trolox and β-carotene equivalents, were in the order: spinach > tomato > carrot by both CUPRAC and ABTS methods. CUPRAC responded favorably to both chlorophylls a and b. The TAC calculated with aid of combined HPLC-spectrophotometry was very close to the spectrophotometric value (93-108%) for real samples and synthetic mixtures.

  7. Final Report: Cooling Seasonal Energy and Peak Demand Impacts of Improved Duct Insulation on Fixed-Capacity (SEER 13) and Variable-Capacity (SEER 22) Heat Pumps

    SciTech Connect

    Withers, C.; Cummings, J.; Nigusse, B.

    2016-09-01

    A new generation of full variable-capacity, central, ducted air-conditioning (AC) and heat pump units has come on the market, and they promise to deliver increased cooling (and heating) efficiency. They are controlled differently than standard single-capacity (fixed-capacity) systems. Instead of cycling on at full capacity and then cycling off when the thermostat is satisfied, they can vary their capacity over a wide range (approximately 40% to 118% of nominal full capacity), thus staying “on” for up to twice as many hours per day compared to fixed-capacity systems of the same nominal capacity. The heating and cooling capacity is varied by adjusting the indoor fan air flow rate, compressor, and refrigerant flow rate as well as the outdoor unit fan air flow rate. Note that two-stage AC or heat pump systems were not evaluated in this research effort. The term dwell is used to refer to the amount of time distributed air spends inside ductwork during space-conditioning cycles. Longer run times mean greater dwell time and therefore greater exposure to conductive gains and losses.

  8. Final Report: Cooling Seasonal Energy and Peak Demand Impacts of Improved Duct Insulation on Fixed-Capacity (SEER 13) and Variable-Capacity (SEER 22) Heat Pumps

    SciTech Connect

    C. Withers; Cummings, J.; Nigusse, B.

    2016-09-08

    A new generation of full variable-capacity, central, ducted air-conditioning (AC) and heat pump units has come on the market, and they promise to deliver increased cooling (and heating) efficiency. They are controlled differently than standard single-capacity (fixed-capacity) systems. Instead of cycling on at full capacity and then cycling off when the thermostat is satisfied, they can vary their capacity over a wide range (approximately 40% to 118% of nominal full capacity), thus staying “on” for up to twice as many hours per day compared to fixed-capacity systems of the same nominal capacity. The heating and cooling capacity is varied by adjusting the indoor fan air flow rate, compressor, and refrigerant flow rate as well as the outdoor unit fan air flow rate. Note that two-stage AC or heat pump systems were not evaluated in this research effort. The term dwell is used to refer to the amount of time distributed air spends inside ductwork during space-conditioning cycles. Longer run times mean greater dwell time and therefore greater exposure to conductive gains and losses.

  9. Evaluation of conditions of comprehensive two-dimensional gas chromatography that yield a near-theoretical maximum in peak capacity gain.

    PubMed

    Klee, Matthew S; Cochran, Jack; Merrick, Mark; Blumberg, Leonid M

    2015-02-27

    The peak capacity gain (Gn) of a GC×GC system is the ratio of the system peak capacity to that of an optimized one-dimensional GC analysis lasting the same time and providing the same detection limit. A near-theoretical maximum in Gn has been experimentally demonstrated in GC×GC-TOF based on a 60m×0.25mm primary column. It was found that Gn was close to 9 compared to the theoretical maximum of about 11 for this system. A six-sigma peak capacity of 4500 was obtained during an 80min heating ramp from 50°C to 320°C. Using peak deconvolution, 2242 individual peaks were determined in a Las Vegas runoff water sample. This is the first definitive experimental demonstration known to us of an order-of-magnitude Gn. The key factors enabling this gain were: relatively sharp (about 20ms at half height) reinjection pulses into the secondary column, relatively long (60m) primary column, the same diameters in primary and secondary columns, relatively low retention factor at the end of the secondary analysis (k≅5 instead of 15, optimal for ideal conditions), optimum flow rate in both columns, and helium (rather than hydrogen) used as the carrier gas. The latter, while making the analysis 65% longer than if using H2, was a better match to the reinjection bandwidth and cycle time.

  10. Robot-assisted gait training improves brachial–ankle pulse wave velocity and peak aerobic capacity in subacute stroke patients with totally dependent ambulation

    PubMed Central

    Han, Eun Young; Im, Sang Hee; Kim, Bo Ryun; Seo, Min Ji; Kim, Myeong Ok

    2016-01-01

    Abstract Objective: Brachial–ankle pulse wave velocity (baPWV) evaluates arterial stiffness and also predicts early outcome in stroke patients. The objectives of this study were to investigate arterial stiffness of subacute nonfunctional ambulatory stroke patients and to compare the effects of robot-assisted gait therapy (RAGT) combined with rehabilitation therapy (RT) on arterial stiffness and functional recovery with those of RT alone. Method: The RAGT group (N = 30) received 30 minutes of robot-assisted gait therapy and 30 minutes of conventional RT, and the control group (N = 26) received 60 minutes of RT, 5 times a week for 4 weeks. baPWV was measured and calculated using an automated device. The patients also performed a symptom-limited graded exercise stress test using a bicycle ergometer, and parameters of cardiopulmonary fitness were recorded. Clinical outcome measures were categorized into 4 categories: activities of daily living, balance, ambulatory function, and paretic leg motor function and were evaluated before and after the 4-week intervention. Results: Both groups exhibited significant functional recovery in all clinical outcome measures after the 4-week intervention. However, peak aerobic capacity, peak heart rate, exercise tolerance test duration, and baPWV improved only in the RAGT group, and the improvements in baPWV and peak aerobic capacity were more noticeable in the RAGT group than in the control group. Conclusion: Robot-assisted gait therapy combined with conventional rehabilitation therapy represents an effective method for reversing arterial stiffness and improving peak aerobic capacity in subacute stroke patients with totally dependent ambulation. However, further large-scale studies with longer term follow-up periods are warranted to measure the effects of RAGT on secondary prevention after stroke. PMID:27741123

  11. The relationship of aerobic capacity, anaerobic peak power and experience to performance in CrossFit exercise.

    PubMed

    Bellar, D; Hatchett, A; Judge, L W; Breaux, M E; Marcus, L

    2015-11-01

    CrossFit is becoming increasingly popular as a method to increase fitness and as a competitive sport in both the Unites States and Europe. However, little research on this mode of exercise has been performed to date. The purpose of the present investigation involving experienced CrossFit athletes and naïve healthy young men was to investigate the relationship of aerobic capacity and anaerobic power to performance in two representative CrossFit workouts: the first workout was 12 minutes in duration, and the second was based on the total time to complete the prescribed exercise. The participants were 32 healthy adult males, who were either naïve to CrossFit exercise or had competed in CrossFit competitions. Linear regression was undertaken to predict performance on the first workout (time) with age, group (naïve or CrossFit athlete), VO2max and anaerobic power, which were all significant predictors (p < 0.05) in the model. The second workout (repetitions), when examined similarly using regression, only resulted in CrossFit experience as a significant predictor (p < 0.05). The results of the study suggest that a history of participation in CrossFit competition is a key component of performance in CrossFit workouts which are representative of those performed in CrossFit, and that, in at least one these workouts, aerobic capacity and anaerobic power are associated with success.

  12. The relationship of aerobic capacity, anaerobic peak power and experience to performance in CrossFit exercise

    PubMed Central

    Hatchett, A; Judge, LW; Breaux, ME; Marcus, L

    2015-01-01

    CrossFit is becoming increasingly popular as a method to increase fitness and as a competitive sport in both the Unites States and Europe. However, little research on this mode of exercise has been performed to date. The purpose of the present investigation involving experienced CrossFit athletes and naïve healthy young men was to investigate the relationship of aerobic capacity and anaerobic power to performance in two representative CrossFit workouts: the first workout was 12 minutes in duration, and the second was based on the total time to complete the prescribed exercise. The participants were 32 healthy adult males, who were either naïve to CrossFit exercise or had competed in CrossFit competitions. Linear regression was undertaken to predict performance on the first workout (time) with age, group (naïve or CrossFit athlete), VO2max and anaerobic power, which were all significant predictors (p < 0.05) in the model. The second workout (repetitions), when examined similarly using regression, only resulted in CrossFit experience as a significant predictor (p < 0.05). The results of the study suggest that a history of participation in CrossFit competition is a key component of performance in CrossFit workouts which are representative of those performed in CrossFit, and that, in at least one these workouts, aerobic capacity and anaerobic power are associated with success. PMID:26681834

  13. Sequential elution liquid chromatography can significantly increase the probability of a successful separation by simultaneously increasing the peak capacity and reducing the separation disorder.

    PubMed

    Socia, Adam; Foley, Joe P

    2014-01-10

    This paper demonstrates that sequential elution liquid chromatography (SE-LC), an approach in which two or more elution modes are employed in series for the separation of two or more groups of compounds, can be used to separate not only weak acids (or weak bases) from neutral compounds, but weak acids and weak bases from neutral compounds (and each other) by the sequential application of either of two types of an extended pH gradient prior to a solvent gradient. It also details a comparison, based on peak capacity and separation disorder, of the probability of success of this approach with the unimodal elution approach taken by conventional column liquid chromatography. For an HPLC peak capacity of 120 and samples of moderate complexity (e.g., 12 components), the probability of success (Rs≥1) increases from 37.9% (HPLC) to 85.8% (SE-LC). Different columns were evaluated for their utility for SE-LC using the following criteria: (1) the prediction of the elution order of the groups based on the degree of ionization of the compounds; and (2) the closeness of the peak shape to the ideal Gaussian distribution. The best columns overall were the Zorbax SB-AQ and Waters XBridge Shield columns, as they provided both between-class and within-class separations of all compounds, as well as the lowest degree of tailing of 4-ethylaniline using the pH 2 to pH 8 gradient.

  14. Deconvolution of gas chromatographic data

    NASA Technical Reports Server (NTRS)

    Howard, S.; Rayborn, G. H.

    1980-01-01

    The use of deconvolution methods on gas chromatographic data to obtain an accurate determination of the relative amounts of each material present by mathematically separating the merged peaks is discussed. Data were obtained on a gas chromatograph with a flame ionization detector. Chromatograms of five xylenes with differing degrees of separation were generated by varying the column temperature at selected rates. The merged peaks were then successfully separated by deconvolution. The concept of function continuation in the frequency domain was introduced in striving to reach the theoretical limit of accuracy, but proved to be only partially successful.

  15. Optimization and Assessment of Three Different High Performance Liquid Chromatographic Systems for the Combinative Fingerprint Analysis and Multi-Ingredients Quantification of Sangju Ganmao Tablet.

    PubMed

    Guo, Meng-Zhe; Han, Jie; He, Dan-Dan; Zou, Jia-Hui; Li, Zheng; Du, Yan; Tang, Dao-Quan

    2017-03-01

    Chromatographic separation is still a critical subject for the quality control of traditional Chinese medicine. In this study, three different high performance liquid chromatographic (HPLC) systems employing commercially available columns packed with 1.8, 3.5 and 5.0 μm particles were respectively developed and optimized for the combinative fingerprint analysis and multi-ingredients quantification of Sangju Ganmao tablet (SGT). Chromatographic parameters including the repeatability of retention time and peak area, symmetry factor, resolution, number of theoretical plates and peak capacity were used to assess the chromatographic performance of different HPLC systems. The optimal chromatographic system using Agilent ZORBAX SB-C18 column (2.1 mm × 100 mm, 3.5 μm) as stationary phase was respectively coupled with diode array detector or mass spectrometry detector for the chromatographic fingerprint analysis and simultaneous quantification or identification of nine compounds of SGT. All the validation data conformed to the acceptable requirements. For the fingerprint analysis, 31 peaks were selected as the common peaks to evaluate the similarities of SGT from 10 different manufacturers using heatmap, hierarchical cluster analysis and principal component analysis. The results demonstrated that the combinations of the quantitative and chromatographic fingerprint analysis offer an efficient way to evaluate the quality consistency of SGT.

  16. Improving Peak Capacity in Fast On-Line Comprehensive Two-Dimensional Liquid Chromatography with Post First Dimension Flow-Splitting

    PubMed Central

    Filgueira, Marcelo R.; Huang, Yuan; Witt, Klaus; Castells, Cecilia; Carr, Peter W.

    2011-01-01

    The use of flow splitters between the two dimensions in on-line comprehensive two dimensional liquid chromatography (LC×LC) has not received very much attention in comparison to their use in GC×GC where they are quite common. In principle, splitting the flow after the first dimension column and performing on-line LC×LC on this constant fraction of the first dimension effluent should allow the two dimensions to be optimized almost independently. When there is no flow splitting any change in the first dimension flow rate has an immediate impact on the second dimension. With a flow splitter one could for example double the flow rate into the first dimension column and do a 1:1 flow split without changing the sample loop size or the sampler’s collection time. Of course, the sensitivity would be diminished but this can be partially compensated by use of a larger injection; this will likely only amount to a small price to pay for this increased resolving power and system flexibility. Among other benefits, we found a 2-fold increase in the corrected 2D peak capacity and the number of observed peaks for a 15 min analysis time by using a post first dimension flow splitter. At a fixed analysis time this improvement results primarily from an increase in the gradient time resulting from the reduced system re-equilibration time and to a smaller extent it is due to the increased peak capacity achieved by full optimization of the first dimension. PMID:22017622

  17. Understanding and design of existing and future chromatographic support formats.

    PubMed

    Billen, J; Desmet, G

    2007-10-19

    The present contribution reviews the use of alternative support formats as a means to surpass the chromatographic performance of the packed bed of spheres. First, a number of idealized structures are considered to obtain a general insight in how the performance of a chromatographic support depends on its shape and size, using the isocratic peak-capacity generation speed as the main performance indicator. Using this criterion, it is found that the packing density or, equivalently, the external porosity, is the most important of all geometrical shape factors. Depending on whether the sample consists of weakly or strongly retained components, the optimal external porosity can be expected to vary between 60% and a value near 100%. The optimal exploitation of a high external porosity, however, also requires overall shrinkage of the domain size, towards and into the sub-micron range. With the current fabrication technologies, this requirement seems difficult to achieve. In the presence of a lower limit on the characteristic support size, each range of desired plate numbers or peak capacities has its own optimal external porosity, ranging from a very low value (high packing density) for high speed, small peak capacity applications, to very high external porosities (low packing density) for applications requiring a very large peak capacity. Subsequently, the obtained theoretical insights are used to review and discuss the past and current research on alternative support formats. Finally, a number of emerging micro- and nano-fabrication technologies are introduced and their potential for the future production of supports with improved shape and homogeneity is discussed.

  18. Fractional coverage metrics based on ecological home range for calculation of the effective peak capacity in comprehensive two-dimensional separations.

    PubMed

    Rutan, Sarah C; Davis, Joe M; Carr, Peter W

    2012-09-14

    Optimization of comprehensive two-dimensional separations frequently relies on the assessment of the peak capacity of the system. A correction is required for the fact that many pairs of separation systems are to some degree correlated, and consequently the entire separation space is not chemically accessible to solutes. This correction is essentially a measure of the fraction of separation space area where the solutes may elute. No agreement exists in the literature as to the best form of the spatial coverage factor. In this work, we distinguish between spatial coverage factors that measure the maximum occupiable space, which is characteristic of the separation dimensionality, and the space actually occupied by a particular sample, which is characteristic of the sample dimensionality. It is argued that the former, which we call f(coverage), is important to calculating the peak capacity. We propose five criteria for a good f(coverage) metric and use them to evaluate various area determination methods that are used to measure animal home ranges in ecology. We consider minimum convex hulls, convex hull peels, α-hulls, three variations of local hull methods, and a kernel method and compare the results to the intuitively satisfying but subjective Stoll-Gilar method. The most promising methods are evaluated using two experimental LC×LC data sets, one with fixed separation chemistry but variable gradient times, and a second with variable first dimension column chemistry. For the 12 separations in the first data set, in which f(coverage) is expected to be constant, the minimum convex hull is the most precise method (f(coverage)=0.68±0.04) that gives similar results to the Stoll-Gilar method (f(coverage)=0.67±0.06). The minimum convex hull is proposed as the best method for calculating f(coverage), because it has no adjustable parameters, can be scaled to different retention time normalizations, is easily calculated using available software, and represents the expected

  19. Chromatographic methods of fractionation.

    PubMed

    Friesen, A D

    1987-01-01

    Chromatography's functional versatility, separation efficiency, gentle non-denaturing separating process and ease of automation and scale-up make it attractive for industrial scale protein purification. The Winnipeg Rh Institute's new Plasma Fractionation facility is an example of the use of chromatography for the large scale purification of plasma protein fractions. The fractionation facility has a capacity to process 800 litres of plasma per batch into blood clotting factor VIII and IX, albumin and intravenous immune serum globulin (i.v. ISG). Albumin and i.v. ISG are purified using ion exchange columns of DEAE-Sepharose (230 litre size), DEAE-Biogel (150 litre size) and CM-Sepharose (150 litre size). The chromatographic process is automated using a Modicon 584 Programmable Logic Controller to regulate valves, pumps and sensors which control plasma flow during fractionation. The stainless steel tanks and piping are automatically cleaned-in-place. The high degree of automation and cleaning provides efficient operation and sanitary processing. Chromatographic methods (DEAE-Sepharose and metal chelation) are also being used at the pilot scale to purify the human blood products superoxide dismutase and hemoglobin from outdated red blood cells. Characterization of the protein fractions produced by chromatography has shown them to be of equal or higher quality than fractions produced by other techniques.

  20. Elimination of chromatographic and mass spectrometric problems in GC-MS analysis of Lavender essential oil by multivariate curve resolution techniques: Improving the peak purity assessment by variable size moving window-evolving factor analysis.

    PubMed

    Jalali-Heravi, Mehdi; Moazeni-Pourasil, Roudabeh Sadat; Sereshti, Hassan

    2015-03-01

    In analysis of complex natural matrices by gas chromatography-mass spectrometry (GC-MS), many disturbing factors such as baseline drift, spectral background, homoscedastic and heteroscedastic noise, peak shape deformation (non-Gaussian peaks), low S/N ratio and co-elution (overlapped and/or embedded peaks) lead the researchers to handle them to serve time, money and experimental efforts. This study aimed to improve the GC-MS analysis of complex natural matrices utilizing multivariate curve resolution (MCR) methods. In addition, to assess the peak purity of the two-dimensional data, a method called variable size moving window-evolving factor analysis (VSMW-EFA) is introduced and examined. The proposed methodology was applied to the GC-MS analysis of Iranian Lavender essential oil, which resulted in extending the number of identified constituents from 56 to 143 components. It was found that the most abundant constituents of the Iranian Lavender essential oil are α-pinene (16.51%), camphor (10.20%), 1,8-cineole (9.50%), bornyl acetate (8.11%) and camphene (6.50%). This indicates that the Iranian type Lavender contains a relatively high percentage of α-pinene. Comparison of different types of Lavender essential oils showed the composition similarity between Iranian and Italian (Sardinia Island) Lavenders.

  1. Comparison of the peak resolution and the stationary phase retention between the satellite and the planetary motions using the coil satellite centrifuge with counter-current chromatographic separation of 4-methylumbelliferyl sugar derivatives.

    PubMed

    Shinomiya, Kazufusa; Zaima, Kazumasa; Harada, Yukina; Yasue, Miho; Harikai, Naoki; Tokura, Koji; Ito, Yoichiro

    2017-01-20

    Coil satellite centrifuge (CSC) produces the complex satellite motion consisting of the triplicate rotation of the coiled column around three axes including the sun axis (the angular velocity, ω1), the planet axis (ω2) and the satellite axis (the central axis of the column) (ω3) according to the following formula: ω1=ω2+ω3. Improved peak resolution in the separation of 4-methylumbelliferyl sugar derivatives was achieved using the conventional multilayer coiled columns with ethyl acetate/1-butanol/water (3: 2: 5, v/v) for the lower mobile phase at the combination of the rotation speeds (ω1, ω2, ω3)=(300, 150, 150rpm), and (1:4:5, v/v) for the upper mobile phase at (300:100:200rpm). The effect of the satellite motion on the peak resolution and the stationary phase retention was evaluated by each CSC separation with the different rotation speeds of ω2 and ω3 under the constant revolution speed at ω1=300rpm. With the lower mobile phase, almost constant peak resolution and stationary phase retention were yielded regardless of the change of ω2 and ω3, while with the upper mobile phase these two values were sensitively varied according to the different combination of ω2 and ω3. For example, when ω2=147 or 200rpm is used, no stationary phase was retained in the coiled column while ω2=150rpm could retain enough volume of stationary phase for separation. On the other hand, the combined rotation speeds at (ω1, ω2, ω3)=(300, 300, 0rpm) or (300, 0, 300rpm) produced insufficient peak resolution regardless of the choice of the mobile phase apparently due to the lack of rotation speed except at (300, 0, 300rpm) with the upper mobile phase. At lower rotation speed of ω1=300rpm, better peak resolution and stationary phase retention were obtained by the satellite motion (ω3) than by the planetary motion (ω2), or ω3>ω2. The effect of the hydrophobicity of the two-phase solvent systems on the stationary phase retention was further examined using the n

  2. High-performance liquid-chromatographic separation of subcomponents of antimycin-A

    USGS Publications Warehouse

    Abidi, S.L.

    1988-01-01

    Using a reversed-phase high-performance liquid chromatographic (HPLC) technique, a mixture of antimycins A was separated into eight hitherto unreported subcomponents, Ala, Alb, A2a, A2b, A3a, A3b, A4a, and A4b. Although a base-line resolution of the known four major antimycins Al, A2, A3, and A4 was readily achieved with mobile phases containing acetate buffers, the separation of the new antibiotic subcomponents was highly sensitive to variation in mobile phase conditions. The type and composition of organic modifiers, the nature of buffer salts, and the concentration of added electrolytes had profound effects on capacity factors, separation factors, and peak resolution values. Of the numerous chromatographic systems examined, a mobile phase consisting of methanol-water (70:30) and 0.005 M tetrabutylammonium phosphate at pH 3.0 yielded the most satisfactory results for the separation of the subcomponents. Reversed-phase gradient HPLC separation of the dansylated or methylated antibiotic compounds produced superior chromatographic characteristics and the presence of added electrolytes was not a critical factor for achieving separation. Differences in the chromatographic outcome between homologous and structural isomers were interpretated based on a differential solvophobic interaction rationale. Preparative reversed-phase HPLC under optimal conditions enabled isolation of pure samples of the methylated antimycin subcomponents for use in structural studies.

  3. High-performance liquid chromatographic separation of subcomponents of antimycin A.

    PubMed

    Abidi, S L

    1988-08-05

    Using a reversed-phase high-performance liquid chromatographic (HPLC) technique, a mixture of antimycins A was separated into eight hitherto unreported subcomponents, A1a, A1b, A2a, A2b, A3a, A3b, A4a, and A4b. Although a base-line resolution of the known four major antimycins A1, A2, A3, and A4 was readily achieved with mobile phases containing acetate buffers, the separation of the new antibiotic subcomponents was highly sensitive to variation in mobile phase conditions. The type and composition of organic modifers, the nature of buffer salts, and the concentration of added electrolytes had profound effects on capacity factors, separation factors, and peak resolution values. Of the numerous chromatographic systems examined, a mobile phase consisting of methanol-water (70:30) and 0.005 M tetrabutylammonium phosphate at pH 3.0 yielded the most satisfactory results for the separation of the subcomponents. Reversed-phase gradient HPLC separation of the dansylated or methylated antibiotic compounds produced superior chromatographic characteristics and the presence of added electrolytes was not a critical factor for achieving separation. Differences in the chromatographic outcome between homologous and structural isomers were interpreted based on a differential solvophobic interaction rationale. Preparative reversed-phase HPLC under optimal conditions enabled isolation of pure samples of the methylated antimycin subcomponents for use in structural studies.

  4. [Development of online conventional array-based two-dimensional liquid chromatographic system for proteins separation in human plasma].

    PubMed

    Huang, Zhi; Hong, Guangfeng; Gao, Mingxia; Zhang, Xiangmin

    2014-04-01

    Human plasma is one of the proteins-containing samples most difficult to characterize on account of the wide dynamic concentration range of its intact proteins. Herein, we developed a high-throughput conventional array-based two-dimensional liquid chromatographic system for proteins separation in human plasma in online mode. In the system, a conventional strong-anion exchange chromatographic column was used as the first separation dimension and eight parallel conventional reversed-phase liquid chromatographic columns were integrated as the second separation dimension. The fractions from the first dimension were sequentially transferred into the corresponding reversed-phase liquid chromatographic precolumns for retention and enrichment using a 10-port electrically actuated multi-position valve. The second dimensional solvent flow was directly and identically split into 8 channels. The fractions were concurrently back-flushed from the precolumns into the 8 conventional RP columns and were separated simultaneously. An 8-channel fraction collector was refitted to collect the reversed-phase liquid chromatographic fractions for further investigation. Bicinchoninic acid (BCA) dyein solution was conveniently used for high-abundance protein location. Two separation dimensions were relatively independent parts, as well as each channel of the second dimensional array separation. Therefore, the new system could improve the separation throughput and total peak capacity. The system was successfully applied for the separation of human plasma intact proteins. The results indicated the established system is an effective method for removing high abundance proteins in plasma and in-depth research in plasma proteomics.

  5. Liquid chromatographic extraction medium

    DOEpatents

    Horwitz, E.P.; Dietz, M.L.

    1994-09-13

    A method and apparatus are disclosed for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water. 1 fig.

  6. Liquid chromatographic extraction medium

    DOEpatents

    Horwitz, E. Philip; Dietz, Mark L.

    1994-01-01

    A method and apparatus for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column is described. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water.

  7. Portable gas chromatograph-mass spectrometer

    DOEpatents

    Andresen, Brian D.; Eckels, Joel D.; Kimmons, James F.; Myers, David W.

    1996-01-01

    A gas chromatograph-mass spectrometer (GC-MS) for use as a field portable organic chemical analysis instrument. The GC-MS is designed to be contained in a standard size suitcase, weighs less than 70 pounds, and requires less than 600 watts of electrical power at peak power (all systems on). The GC-MS includes: a conduction heated, forced air cooled small bore capillary gas chromatograph, a small injector assembly, a self-contained ion/sorption pump vacuum system, a hydrogen supply, a dual computer system used to control the hardware and acquire spectrum data, and operational software used to control the pumping system and the gas chromatograph. This instrument incorporates a modified commercial quadrupole mass spectrometer to achieve the instrument sensitivity and mass resolution characteristic of laboratory bench top units.

  8. Portable gas chromatograph-mass spectrometer

    DOEpatents

    Andresen, B.D.; Eckels, J.D.; Kimmons, J.F.; Myers, D.W.

    1996-06-11

    A gas chromatograph-mass spectrometer (GC-MS) is described for use as a field portable organic chemical analysis instrument. The GC-MS is designed to be contained in a standard size suitcase, weighs less than 70 pounds, and requires less than 600 watts of electrical power at peak power (all systems on). The GC-MS includes: a conduction heated, forced air cooled small bore capillary gas chromatograph, a small injector assembly, a self-contained ion/sorption pump vacuum system, a hydrogen supply, a dual computer system used to control the hardware and acquire spectrum data, and operational software used to control the pumping system and the gas chromatograph. This instrument incorporates a modified commercial quadrupole mass spectrometer to achieve the instrument sensitivity and mass resolution characteristic of laboratory bench top units. 4 figs.

  9. Portable gas chromatograph-mass spectrometer

    SciTech Connect

    Andresen, B.D.; Eckels, J.D.; Kimmins, J.F.; Myers, D.W.

    1994-12-31

    A gas chromatograph-mass spectrometer (GC-MS) for use as a field portable organic chemical analysis instrument. The GC-MS is designed to be contained in a standard size suitcase, weighs less than 70 pounds, and requires less than 600 watts of electrical power at peak power (all systems on). The GC-MS includes: a conduction heated, forced air cooled small bore capillary gas chromatograph, a small injector assembly, a self-contained ion/sorption pump vacuum system, a hydrogen supply, a dual computer system used to control the hardware and acquire spectrum data, and operational software used to control the pumping system and the gas chromatograph. This instrument incorporates a modified commercial quadrupole mass spectrometer to achieve the instrument sensitivity and mass resolution characteristic of laboratory bench top units.

  10. Electrochemical behavior of chlorogenic acid at a boron-doped diamond electrode and estimation of the antioxidant capacity in the coffee samples based on its oxidation peak.

    PubMed

    Yardım, Yavuz

    2012-04-01

    In this study, an electroanalytical methodology for the determination of chlorogenic acid (CGA) was achieved at a boron-doped diamond electrode under adsorptive transfer stripping voltammetric conditions. The values obtained for CGA were used to estimate the antioxidant properties of the coffee sample based on CGA oxidation. By using square-wave stripping mode, the compound yielded a well-defined voltammetric response at +0.49 V with respect to Ag/AgCl in Britton-Robinson buffer at pH 3.0 (after 120 s accumulations at a fixed potential of 0.40 V). At the optimum experimental conditions, linear calibration curve is obtained within the concentration range of 0.25 to 4.0 μg mL⁻¹ with the limit of detection 0.049 μg mL⁻¹ . The developed protocol was successfully applied for the analysis of antioxidant capacity in the coffee products such as Turkish coffee and instant coffee.

  11. Twin Peaks

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The two hills in the distance, approximately one to two kilometers away, have been dubbed the 'Twin Peaks' and are of great interest to Pathfinder scientists as objects of future study. The white areas on the left hill, called the 'Ski Run' by scientists, may have been formed by hydrologic processes.

    The image was taken by the Imager for Mars Pathfinder (IMP) after its deployment on Sol 3. Mars Pathfinder was developed and managed by the Jet Propulsion Laboratory (JPL) for the National Aeronautics and Space Administration. The IMP was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

  12. Chromatographic hydrogen isotope separation

    DOEpatents

    Aldridge, Frederick T.

    1981-01-01

    Intermetallic compounds with the CaCu.sub.5 type of crystal structure, particularly LaNiCo.sub.4 and CaNi.sub.5, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation colum. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale mutli-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen can produce large quantities of heavy water at an effective cost for use in heavy water reactors.

  13. Chromatographic hydrogen isotope separation

    DOEpatents

    Aldridge, F.T.

    Intermetallic compounds with the CaCu/sub 5/ type of crystal structure, particularly LaNiCo/sub 4/ and CaNi/sub 5/, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation column. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale multi-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen cn produce large quantities of heavy water at an effective cost for use in heavy water reactors.

  14. General theory of peak compression in liquid chromatography.

    PubMed

    Gritti, Fabrice

    2016-02-12

    A new and general expression of the peak compression factor in liquid chromatography is derived. It applies to any type of gradients induced by non-uniform columns (stationary) or by temporal variations (dynamic) of the elution strength related to changes in solvent composition, temperature, or in any external field. The new equation is validated in two ideal cases for which the exact solutions are already known. From a practical viewpoint, it is used to predict the achievable degree of peak compression for curved retention models, retained solvent gradients, and for temperature-programmed liquid chromatography. The results reveal that: (1) curved retention models affect little the compression factor with respect to the best linear strength retention models, (2) gradient peaks can be indefinitely compressed with respect to isocratic peaks if the propagation speed of the gradient (solvent or temperature) becomes smaller than the chromatographic velocity, (3) limitations are inherent to the maximum intensity of the experimental intrinsic gradient steepness, and (4) dynamic temperature gradients can be advantageously combined to solvent gradients in order to improve peak capacities of microfluidic separation devices.

  15. Chromatographic Degradation of Phloridzin

    PubMed Central

    Grochowska, Maria J.

    1966-01-01

    Phloridzin, the main phenolic glucoside in apple leaves, has been found to undergo transformation during chromatography. When chromatographed repeatedly in ammoniacal solvents, at least 2 new derivatives appeared. One of these was identified as phloretic acid. When bioassayed in the presence of indole-3-acetic acid this substance behaved as though it promoted the destruction of the auxin. Comparative bioassay with naphthaleneacetic acid suggested that phloretic acid acts on indoleacetic acid destruction via stimulation of indoleacetic acid oxidase. However, at low concentration and in presence of a small amount of phloridzin it also showed a synergistic effect with indoleacetic acid. A substance with the same characteristics was obtained directly from apple leaves, which are known to contain phloridzin when the extracts were chromatographed only once in the same (alkaline) solvent. While not completely confirmed, this suggests that phloretic acid is normally present in apple leaves, where it may affect growth there by promoting indoleacetic acid oxidation. Images PMID:16656273

  16. Gas chromatograph injection system

    NASA Technical Reports Server (NTRS)

    Pollock, G. E.; Henderson, M. E.; Donaldson, R. W., Jr. (Inventor)

    1975-01-01

    An injection system for a gas chromatograph is described which uses a small injector chamber (available in various configurations). The sample is placed in the chamber while the chamber is not under pressure and is not heated, and there is no chance of leakage caused by either pressure or heat. It is injected into the apparatus by changing the position of a valve and heating the chamber, and is volatilized and swept by a carrier gas into the analysis apparatus.

  17. Chromatographic fingerprint analysis of Pycnogenol dietary supplements.

    PubMed

    Chen, Pei; Song, Fenhong; Lin, Long-Ze

    2009-01-01

    The bark of maritime pine (Pinus pinaster Aiton) has been widely used as a remedy for various degenerative diseases. A standard high-performance liquid chromatographic (HPLC) procedure for Pycnogenol analysis is a method specified in the United States Pharmacopeia (USP) monograph, which requires measurement of peak areas and identification of four components of the extract: caffeic acid, catechin, ferulic acid, and taxifolin. In this study, a fingerprint analysis using an HPLC method based on the USP monograph has been developed to provide additional qualitative information for the analysis of Pycnogenol-containing dietary supplements (PDS). Twelve commercially available PDS samples were purchased and analyzed along with a standard Pycnogenol extract. Their chromatographic fingerprints were analyzed using principal component analysis. The results showed that two of the samples were not consistent with the standard reference Pycnogenol extract. One contained other active ingredients in addition to Pycnogenol, and the other may have resulted from a quality control issue in manufacturing.

  18. Ion-exchange chromatographic analysis of peroxynitric acid.

    PubMed

    Nakashima, Yoichi; Ikawa, Satoshi; Tani, Atsushi; Kitano, Katsuhisa

    2016-01-29

    Ion-exchange chromatographic analysis of peroxynitric acid (O2NOOH) was performed by combining an acidic eluate with an UV-vis detector and immersing the separation column in an ice-water bath. The decomposition behavior of peroxynitric acid in the solution was also studied using this system. The fraction for the peroxynitric acid peak was collected. Ion-exchange chromatographic analysis of this fraction, after standing at room temperature for 24h, showed that the decomposition products were mainly nitrate ions with a very small amount of nitrous acid. The peroxynitric acid peak area correlated perfectly with the total amount of decomposition products. The ion-exchange chromatographic isolation allowed us to evaluate the molar extinction coefficient of peroxynitric acid precisely in a wider wavelength range than previous reports. The value decreases monotonically from 1729±26M(-1)cm(-1) at 200nm to 12.0±0.5M(-1)cm(-1) at 290nm.

  19. Chromatographic separation and concentration of quercetin and (+)-catechin using mesoporous composites based on MCM-41

    NASA Astrophysics Data System (ADS)

    Karpov, S. I.; Belanova, N. A.; Korabel'nikova, E. O.; Nedosekina, I. V.; Roessner, F.; Selemenev, V. F.

    2015-05-01

    Data on chromatographic separation of quercetin and (+)-catechin-flavonoids with similar physicochemical (including sorption) properties—are presented. The highest efficiency of chromatographic process at high sorption capacity of the material with respect to quercetin and slightly lower capacity for (+)-catechin were observed when silylated composites of ordered MCM-41 type materials were used. The application of acetonitrile as a solvent increased the sorption capacity of the material and can be recommended for separation of related polyphenol substances and their determination using ordered MCM-41 modified with trimethylchlorosilane as a stationary phase in a chromatographic column.

  20. Microminiature gas chromatograph

    DOEpatents

    Yu, C.M.

    1996-12-10

    A microminiature gas chromatograph ({mu}GC) comprising a least one silicon wafer, a gas injector, a column, and a detector. The gas injector has a normally closed valve for introducing a mobile phase including a sample gas in a carrier gas. The valve is fully disposed in the silicon wafer(s). The column is a microcapillary in silicon crystal with a stationary phase and is mechanically connected to receive the mobile phase from the gas injector for the molecular separation of compounds in the sample gas. The detector is mechanically connected to the column for the analysis of the separated compounds of sample gas with electronic means, e.g., ion cell, field emitter and PIN diode. 7 figs.

  1. Microminiature gas chromatograph

    DOEpatents

    Yu, Conrad M.

    1996-01-01

    A microminiature gas chromatograph (.mu.GC) comprising a least one silicon wafer, a gas injector, a column, and a detector. The gas injector has a normally closed valve for introducing a mobile phase including a sample gas in a carrier gas. The valve is fully disposed in the silicon wafer(s). The column is a microcapillary in silicon crystal with a stationary phase and is mechanically connected to receive the mobile phase from the gas injector for the molecular separation of compounds in the sample gas. The detector is mechanically connected to the column for the analysis of the separated compounds of sample gas with electronic means, e.g., ion cell, field emitter and PIN diode.

  2. Chromatographic fingerprints analysis for evaluation of Ginkgo Biloba products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The leaf extract of Ginkgo biloba has purported value for improving mental capacities in Alzheimer’s patients. The flavonoids and the terpene lactones are considered to be the two main active components that influence human health. This paper compared an LC/UV chromatographic fingerprint method wi...

  3. Versatile gas/particle ion chromatograph.

    PubMed

    Ullah, S M Rahmat; Takeuchi, Masaki; Dasgupta, Purnendu K

    2006-02-01

    A new, compact gas/particle ion chromatograph has been developed for measuring ionic constituents in PM2.5 (particulate matter of aerodynamic diameter < or = 2.5 microm) and water-soluble ionogenic gases. The instrument has separate sampling channels for gases and particles. In one, a membrane denuder collects soluble gases for preconcentration and analysis. In the other, a cyclone removes larger particles, a membrane denuder removes soluble gases, and a continuously wetted hydrophilic filter collects particles. A single, multiport, syringe pump handles liquid transport, and one conductivity detector measures anions and ammonium for both channels. Electrodialytically generated gradient hydroxide eluent permits 20 min chromatographic runs. Gas/particle samples are each collected for 40 min, butthe sampling intervals are staggered by 20 min. Liquid samples from the gas denuder and particle collector are aspirated and preconcentrated on sequential cation and anion concentrators and transferred respectively to an ammonia transfer device and an anion separation column. The flow configuration results in an ammonium peak before anion peaks in the chromatogram. The system measures ammonia, organic acids (such as acetic, formic, and oxalic acids), HCl, HONO, SO2, HNO3, and the corresponding ions in the aerosol phase. Low ng/m3 to sub-ng/m3 limits of detection (LODs) are attained for most common gases and particulate constituents, the LODs for gaseous SO2 to NH3 range, for example, from sub parts per trillion by volume (sub-pptv) to approximately 5 pptv.

  4. [Combination similarity algorithm on chromatographic fingerprints].

    PubMed

    Zhan, Xueyan; Shi, Xinyuan; Duan, Tianxuan; Li, Lei; Qiao, Yanjiang

    2010-11-01

    The similarity of chromatographic fingerprints is one of the effective approaches evaluating the quality stability of Chinese medicine, and the cosine of angle plays an important role in the application of similarity. However, the cosine approach is insensitive to the data difference when the distribution range of the data sets is wide. When the data proportion of the reference sample and the test sample is greatly different, it confirms that the sensitivity of the cosine to the differences of the peaks owned by both the reference sample and the test sample differs from the peaks owned only by the reference sample or the test sample in this study. The method considers the peaks owned by one sample in addition to peaks owned by both samples, and determines their own appropriate weigh targeting for the maximal homostasis value of proportion among the peaks of all of Smilax glabra Roxb. samples. The method based on sample data could reflect the difference in the chemical composition area ratio between the reference sample and test samples sensitively, and measures the similarity among the nine Smilax glabra Roxb. samples, which is a new similarity algorithm for evaluating the quality stability of herbal medicines.

  5. Peak Oil, Peak Coal and Climate Change

    NASA Astrophysics Data System (ADS)

    Murray, J. W.

    2009-05-01

    Research on future climate change is driven by the family of scenarios developed for the IPCC assessment reports. These scenarios create projections of future energy demand using different story lines consisting of government policies, population projections, and economic models. None of these scenarios consider resources to be limiting. In many of these scenarios oil production is still increasing to 2100. Resource limitation (in a geological sense) is a real possibility that needs more serious consideration. The concept of 'Peak Oil' has been discussed since M. King Hubbert proposed in 1956 that US oil production would peak in 1970. His prediction was accurate. This concept is about production rate not reserves. For many oil producing countries (and all OPEC countries) reserves are closely guarded state secrets and appear to be overstated. Claims that the reserves are 'proven' cannot be independently verified. Hubbert's Linearization Model can be used to predict when half the ultimate oil will be produced and what the ultimate total cumulative production (Qt) will be. US oil production can be used as an example. This conceptual model shows that 90% of the ultimate US oil production (Qt = 225 billion barrels) will have occurred by 2011. This approach can then be used to suggest that total global production will be about 2200 billion barrels and that the half way point will be reached by about 2010. This amount is about 5 to 7 times less than assumed by the IPCC scenarios. The decline of Non-OPEC oil production appears to have started in 2004. Of the OPEC countries, only Saudi Arabia may have spare capacity, but even that is uncertain, because of lack of data transparency. The concept of 'Peak Coal' is more controversial, but even the US National Academy Report in 2007 concluded only a small fraction of previously estimated reserves in the US are actually minable reserves and that US reserves should be reassessed using modern methods. British coal production can be

  6. New Method for Evaluating Irreversible Adsorption and Stationary Phase Bleed in Gas Chromatographic Capillary Columns

    SciTech Connect

    Wright, Bob W.; Wright, Cherylyn W.

    2012-10-26

    A novel method for the evaluation of gas chromatographic (GC) column inertness has been developed using a tandem GC approach. Typically column inertness is measured by analyte peak shape evaluation. In general, silica, glass, and metal surfaces are chemically reactive and can cause analyte adsorption, which typically is observed as chromatographic peak tailing. Adsorption processes produce broad, short chromatographic peaks that confound peak area determinations because a significant portion can reside in the noise. In addition, chromatographic surfaces and stationary phases can irreversibly adsorb certain analytes without obvious degradation of peak shape. The inertness measurements described in this work specifically determine the degree of irreversible adsorption behavior of specific target compounds at levels ranging from approximately 50 picograms to 1 nanogram on selected gas chromatographic columns. Chromatographic columns with 5% phenylmethylsiloxane, polyethylene glycol (wax), trifluoropropylsiloxane, and 78% cyanopropylsiloxane stationary phases were evaluated with a variety of phosphorus- and sulfur- containing compounds selected as test compounds due to their ease of adsorption and importance in trace analytical detection. In addition, the method was shown effective for characterizing column bleed.

  7. A new concept for variance analysis of hyphenated chromatographic data avoiding signal warping.

    PubMed

    Zerzucha, Piotr; Kazura, Małgorzata; de Beer, Dalene; Joubert, Elizabeth; Schulze, Alexandra E; Beelders, Theresa; de Villiers, André; Walczak, Beata

    2013-05-24

    Analysis of variance of chromatographic data is usually performed on the peak table or on entire chromatograms. These two data forms require signal pretreatment. Peak table requires peak detection, their standards and quantification, and the second form of data organization requires warping of the studied chromatograms to eliminate the observed peak shifts, which occurs due to minor variations in chromatographic conditions. In our study, a new form of data representation well suited for chromatographic data originating from multi-channel detection is proposed. It requires neither warping of chromatograms, nor peak detection. Its principles and performance are demonstrated for a real data set (being a part of a larger research project initiated to characterize the infusion of fermented rooibos herbal tea in terms of phenolic composition and antioxidant activity). As the method of choice for the analysis of data variation, the Multiple Analysis of Variance applied to the pairwise data representation was chosen.

  8. Dual liquid and gas chromatograph system

    DOEpatents

    Gay, D.D.

    A chromatographic system is described that utilizes one detection system for gas chromatographic and micro-liquid chromatographic determinations. The detection system is a direct-current, atmospheric-pressure, helium plasma emission spectrometer. The detector utilizes a nontransparent plasma source unit which contains the plasma region and two side-arms which receive effluents from the micro-liquid chromatograph and the gas chromatograph. The dual nature of this chromatographic system offers: (1) extreme flexibility in the samples to be examined; (2) extreme low sensitivity; (3) element selectivity; (4) long-term stability; (5) direct correlation of data from the liquid and gas samples; (6) simpler operation than with individual liquid and gas chromatographs, each with different detection systems; and (7) cheaper than a commercial liquid chromatograph and a gas chromatograph.

  9. Dual liquid and gas chromatograph system

    DOEpatents

    Gay, Don D.

    1985-01-01

    A chromatographic system that utilizes one detection system for gas chromatographic and micro-liquid chromatographic determinations. The detection system is a direct-current, atmospheric-pressure, helium plasma emission spectrometer. The detector utilizes a non-transparent plasma source unit which contains the plasma region and two side-arms which receive effluents from the micro-liquid chromatograph and the gas chromatograph. The dual nature of this chromatographic system offers: (1) extreme flexibility in the samples to be examined; (2) extremely low sensitivity; (3) element selectivity; (4) long-term stability; (5) direct correlation of data from the liquid and gas samples; (6) simpler operation than with individual liquid and gas chromatographs, each with different detection systems; and (7) cheaper than a commercial liquid chromatograph and a gas chromatograph.

  10. Methods and apparatus for analysis of chromatographic migration patterns

    DOEpatents

    Stockham, Thomas G.; Ives, Jeffrey T.

    1993-01-01

    A method and apparatus for sharpening signal peaks in a signal representing the distribution of biological or chemical components of a mixture separated by a chromatographic technique such as, but not limited to, electrophoresis. A key step in the method is the use of a blind deconvolution technique, presently embodied as homomorphic filtering, to reduce the contribution of a blurring function to the signal encoding the peaks of the distribution. The invention further includes steps and apparatus directed to determination of a nucleotide sequence from a set of four such signals representing DNA sequence data derived by electrophoretic means.

  11. Methods and apparatus for analysis of chromatographic migration patterns

    DOEpatents

    Stockham, T.G.; Ives, J.T.

    1993-12-28

    A method and apparatus are presented for sharpening signal peaks in a signal representing the distribution of biological or chemical components of a mixture separated by a chromatographic technique such as, but not limited to, electrophoresis. A key step in the method is the use of a blind deconvolution technique, presently embodied as homomorphic filtering, to reduce the contribution of a blurring function to the signal encoding the peaks of the distribution. The invention further includes steps and apparatus directed to determination of a nucleotide sequence from a set of four such signals representing DNA sequence data derived by electrophoretic means. 16 figures.

  12. PeakWorks

    SciTech Connect

    2016-11-30

    The PeakWorks software is designed to assist in the quantitative analysis of atom probe tomography (APT) generated mass spectra. Specifically, through an interactive user interface, mass peaks can be identified automatically (defined by a threshold) and/or identified manually. The software then provides a means to assign specific elemental isotopes (including more than one) to each peak. The software also provides a means for the user to choose background subtraction of each peak based on background fitting functions, the choice of which is left to the users discretion. Peak ranging (the mass range over which peaks are integrated) is also automated allowing the user to chose a quantitative range (e.g. full-widthhalf- maximum). The software then integrates all identified peaks, providing a background-subtracted composition, which also includes the deconvolution of peaks (i.e. those peaks that happen to have overlapping isotopic masses). The software is also able to output a 'range file' that can be used in other software packages, such as within IVAS. A range file lists the peak identities, the mass range of each identified peak, and a color code for the peak. The software is also able to generate 'dummy' peak ranges within an outputted range file that can be used within IVAS to provide a means for background subtracted proximity histogram analysis.

  13. Peak flow meter (image)

    MedlinePlus

    A peak flow meter is commonly used by a person with asthma to measure the amount of air that can be ... become narrow or blocked due to asthma, peak flow values will drop because the person cannot blow ...

  14. Considerations on the temperature dependence of the gas-liquid chromatographic retention.

    PubMed

    González, Francisco Rex

    2002-01-04

    A discussion on the temperature dependence of the partition coefficient K is developed. This discussion embraces topics such as the limitations of conventional thermodynamic approaches followed in the chromatographic literature, qualitative theoretical notions arising from molecular thermodynamics and the experimental information that is accessible through modern capillary gas chromatography. It is shown that the heat capacity difference of solute transfer for flexible molecules has at least one maximum in the chromatographic range of temperature. As a consequence, a great amount of experimental data is required for a correct thermodynamic interpretation of the chromatographic retention.

  15. Ask the experts: chromatographic baselines.

    PubMed

    Smith, Graeme; James, Christopher A; Scott, Rebecca; Woolf, Eric

    2014-05-01

    Bioanalysis invited a selection of leading researchers to express their views on chromatographic baseline assignment in the bioanalytical laboratory. The topics discussed include the challenges presented with ensuring automated baseline assignment is correct, when reintegration is necessary, regulation and consistency in terminology. Their enlightening responses provide a valuable insight into developing an industry consensus towards reintegration. An accompanying commentary article in this issue, authored by Howard Hill and colleagues (Huntingdon Life Sciences), provides background to this much debated topic.

  16. Comparison of three liquid chromatographic methods for egg-white protein analysis.

    PubMed

    Awadé, A C; Efstathiou, T

    1999-02-19

    This paper describes and compares three chromatographic methods for the analysis of egg-white proteins. Gel-permeation chromatography allowed the separation of seven peaks from egg white, with an almost total protein recovery. A clean separation of ovomucin and lysozyme from the bulk of the proteins was obtained with this method. Reversed-phase high-performance liquid chromatography led to the fractionation of at least eight peaks. With this chromatographic method, the recovery was relatively poor. Approximately 30% of the ovalbumin was retained in the column after the elution. Finally, eleven chromatographic peaks were separated from egg white by high-performance liquid chromatography on an anion-exchange column. The recovery of proteins was almost total. The latter method afforded higher resolution.

  17. Are Bragg Peaks Gaussian?

    PubMed Central

    Hammouda, Boualem

    2014-01-01

    It is common practice to assume that Bragg scattering peaks have Gaussian shape. The Gaussian shape function is used to perform most instrumental smearing corrections. Using Monte Carlo ray tracing simulation, the resolution of a realistic small-angle neutron scattering (SANS) instrument is generated reliably. Including a single-crystal sample with large d-spacing, Bragg peaks are produced. Bragg peaks contain contributions from the resolution function and from spread in the sample structure. Results show that Bragg peaks are Gaussian in the resolution-limited condition (with negligible sample spread) while this is not the case when spread in the sample structure is non-negligible. When sample spread contributes, the exponentially modified Gaussian function is a better account of the Bragg peak shape. This function is characterized by a non-zero third moment (skewness) which makes Bragg peaks asymmetric for broad neutron wavelength spreads. PMID:26601025

  18. Peak Experience Project

    ERIC Educational Resources Information Center

    Scott, Daniel G.; Evans, Jessica

    2010-01-01

    This paper emerges from the continued analysis of data collected in a series of international studies concerning Childhood Peak Experiences (CPEs) based on developments in understanding peak experiences in Maslow's hierarchy of needs initiated by Dr Edward Hoffman. Bridging from the series of studies, Canadian researchers explore collected…

  19. Vibrational Spectroscopy of Chromatographic Interfaces

    SciTech Connect

    Jeanne E. Pemberton

    2011-03-10

    Chromatographic separations play a central role in DOE-supported fundamental research related to energy, biological systems, the environment, and nuclear science. The overall portfolio of research activities in the Separations and Analysis Program within the DOE Office of Basic Energy Sciences includes support for activities designed to develop a molecular-level understanding of the chemical processes that underlie separations for both large-scale and analytical-scale purposes. The research effort funded by this grant award was a continuation of DOE-supported research to develop vibrational spectroscopic methods to characterize the interfacial details of separations processes at a molecular level.

  20. Significance of periodogram peaks

    NASA Astrophysics Data System (ADS)

    Süveges, Maria; Guy, Leanne; Zucker, Shay

    2016-10-01

    Three versions of significance measures or False Alarm Probabilities (FAPs) for periodogram peaks are presented and compared for sinusoidal and box-like signals, with specific application on large-scale surveys in mind.

  1. Peak power ratio generator

    DOEpatents

    Moyer, R.D.

    A peak power ratio generator is described for measuring, in combination with a conventional power meter, the peak power level of extremely narrow pulses in the gigahertz radio frequency bands. The present invention in a preferred embodiment utilizes a tunnel diode and a back diode combination in a detector circuit as the only high speed elements. The high speed tunnel diode provides a bistable signal and serves as a memory device of the input pulses for the remaining, slower components. A hybrid digital and analog loop maintains the peak power level of a reference channel at a known amount. Thus, by measuring the average power levels of the reference signal and the source signal, the peak power level of the source signal can be determined.

  2. Peak power ratio generator

    DOEpatents

    Moyer, Robert D.

    1985-01-01

    A peak power ratio generator is described for measuring, in combination with a conventional power meter, the peak power level of extremely narrow pulses in the gigahertz radio frequency bands. The present invention in a preferred embodiment utilizes a tunnel diode and a back diode combination in a detector circuit as the only high speed elements. The high speed tunnel diode provides a bistable signal and serves as a memory device of the input pulses for the remaining, slower components. A hybrid digital and analog loop maintains the peak power level of a reference channel at a known amount. Thus, by measuring the average power levels of the reference signal and the source signal, the peak power level of the source signal can be determined.

  3. Pikes Peak, Colorado

    USGS Publications Warehouse

    Brunstein, Craig; Quesenberry, Carol; Davis, John; Jackson, Gene; Scott, Glenn R.; D'Erchia, Terry D.; Swibas, Ed; Carter, Lorna; McKinney, Kevin; Cole, Jim

    2006-01-01

    For 200 years, Pikes Peak has been a symbol of America's Western Frontier--a beacon that drew prospectors during the great 1859-60 Gold Rush to the 'Pikes Peak country,' the scenic destination for hundreds of thousands of visitors each year, and an enduring source of pride for cities in the region, the State of Colorado, and the Nation. November 2006 marks the 200th anniversary of the Zebulon M. Pike expedition's first sighting of what has become one of the world's most famous mountains--Pikes Peak. In the decades following that sighting, Pikes Peak became symbolic of America's Western Frontier, embodying the spirit of Native Americans, early explorers, trappers, and traders who traversed the vast uncharted wilderness of the Western Great Plains and the Southern Rocky Mountains. High-quality printed paper copies of this poster are available at no cost from Information Services, U.S. Geological Survey (1-888-ASK-USGS).

  4. Correlation-Peak Imaging

    NASA Astrophysics Data System (ADS)

    Ziegler, A.; Metzler, A.; Köckenberger, W.; Izquierdo, M.; Komor, E.; Haase, A.; Décorps, M.; von Kienlin, M.

    1996-08-01

    Identification and quantitation in conventional1H spectroscopic imagingin vivois often hampered by the small chemical-shift range. To improve the spectral resolution of spectroscopic imaging, homonuclear two-dimensional correlation spectroscopy has been combined with phase encoding of the spatial dimensions. From the theoretical description of the coherence-transfer signal in the Fourier-transform domain, a comprehensive acquisition and processing strategy is presented that includes optimization of the width and the position of the acquisition windows, matched filtering of the signal envelope, and graphical presentation of the cross peak of interest. The procedure has been applied to image the spatial distribution of the correlation peaks from specific spin systems in the hypocotyl of castor bean (Ricinus communis) seedlings. Despite the overlap of many resonances, correlation-peak imaging made it possible to observe a number of proton resonances, such as those of sucrose, β-glucose, glutamine/glutamate, lysine, and arginine.

  5. Hale Central Peak

    NASA Technical Reports Server (NTRS)

    2004-01-01

    19 September 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the mountains that make up the central peak region of Hale Crater, located near 35.8oS, 36.5oW. Dark, smooth-surfaced sand dunes are seen to be climbing up the mountainous slopes. The central peak of a crater consists of rock brought up during the impact from below the crater floor. This autumn image is illuminated from the upper left and covers an area approximately 3 km (1.9 mi) across.

  6. Make peak flow a habit!

    MedlinePlus

    Asthma - make peak flow a habit; Reactive airway disease - peak flow; Bronchial asthma - peak flow ... your airways are narrowed and blocked due to asthma, your peak flow values drop. You can check ...

  7. Reverse-phase high pressure liquid chromatographic analysis of harpagoside, scorodioside and verbascoside from Scrophularia scorodonia: quantitative determination of harpagoside.

    PubMed

    Díaz, A; Fernández, L; Ollivier, E; Martín, T; Villaescusa, L; Balansard, G

    1998-02-01

    A reversed-phase high performance liquid chromatographic method has been developed for the determination of the main compounds (harpagoside, scorodioside, and verbascoside) from different samples of Scrophularia scorodonia. The chromatographic method has been validated and applied for quantitative determination of harpagoside. The results show the highest levels of harpagoside in the leaf extract. The purity and identity of peaks were controlled by diode-array detection and comparison with standards.

  8. Absorption, Creativity, Peak Experiences, Empathy, and Psychoticism.

    ERIC Educational Resources Information Center

    Mathes, Eugene W.; And Others

    Tellegen and Atkinson suggested that the trait of absorption may play a part in meditative skill, creativity, capacity for peak experiences, and empathy. Although the absorption-meditative skill relationship has been confirmed, other predictions have not been tested. Tellegen and Atkinson's Absorption Scale was completed by undergraduates in four…

  9. Impact Crater with Peak

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 14 June 2002) The Science This THEMIS visible image shows a classic example of a martian impact crater with a central peak. Central peaks are common in large, fresh craters on both Mars and the Moon. This peak formed during the extremely high-energy impact cratering event. In many martian craters the central peak has been either eroded or buried by later sedimentary processes, so the presence of a peak in this crater indicates that the crater is relatively young and has experienced little degradation. Observations of large craters on the Earth and the Moon, as well as computer modeling of the impact process, show that the central peak contains material brought from deep beneath the surface. The material exposed in these peaks will provide an excellent opportunity to study the composition of the martian interior using THEMIS multi-spectral infrared observations. The ejecta material around the crater can is well preserved, again indicating relatively little modification of this landform since its initial creation. The inner walls of this approximately 18 km diameter crater show complex slumping that likely occurred during the impact event. Since that time there has been some downslope movement of material to form the small chutes and gullies that can be seen on the inner crater wall. Small (50-100 m) mega-ripples composed of mobile material can be seen on the floor of the crater. Much of this material may have come from the walls of the crater itself, or may have been blown into the crater by the wind. The Story When a meteor smacked into the surface of Mars with extremely high energy, pow! Not only did it punch an 11-mile-wide crater in the smoother terrain, it created a central peak in the middle of the crater. This peak forms kind of on the 'rebound.' You can see this same effect if you drop a single drop of milk into a glass of milk. With craters, in the heat and fury of the impact, some of the land material can even liquefy. Central peaks like the one

  10. Utilization of a diol-stationary phase column in ion chromatographic separation of inorganic anions.

    PubMed

    Arai, Kaori; Mori, Masanobu; Kozaki, Daisuke; Nakatani, Nobutake; Itabashi, Hideyuki; Tanaka, Kazuhiko

    2012-12-28

    We describe the ion chromatographic separation of inorganic anions using a diol-stationary phase column (-CH(OH)CH(2)OH; diol-column) without charged functional groups. Anions were separated using acidic eluent as in typical anion-exchange chromatography. The retention volumes of anions on the diol-column increased with increasing H(+) concentration in the eluent. The anion-exchange capacities of diol-columns in the acidic eluent (pH 2.8) were larger than that of zwitterionic stationary phase column but smaller than that of an anion-exchange column. The separation of anions using the diol-column was strongly affected by the interaction of H(+) ions with the diol-functional groups and by the types of the eluents. In particular, the selection of the eluent was very important for controlling the retention time and resolution. Good separation was obtained using a diol-column (HILIC-10) with 5 mM phthalic acid as eluent. The limits of detection at a signal-to-noise ratio of 3 ranged from 1.2 to 2.7 μM with relative standard deviations (RSD, n=5) of 0.04-0.07% for the retention time and 0.4-2.0% for the peak areas. This method was successfully applied to the determination of H(2)PO(4)(-), Cl(-), and NO(3)(-) in a liquid fertilizer sample.

  11. Comprehensive two-dimensional liquid chromatographic analysis of rooibos (Aspalathus linearis) phenolics.

    PubMed

    Beelders, Theresa; Kalili, Kathithileni M; Joubert, Elizabeth; de Beer, Dalene; de Villiers, André

    2012-07-01

    Rooibos tea is an unique beverage prepared from unfermented and fermented plant material of the endemic Cape fynbos plant, Aspalathus linearis. The well-known health-promoting benefits of rooibos are partly attributed to its phenolic composition. Detailed investigation of the minor phenolic constituents of rooibos is, however, hampered by the limitations associated with conventional HPLC methods used for its analysis. In this study, the applicability of comprehensive two-dimensional liquid chromatographic methods for the in-depth analysis of rooibos phenolics was investigated. Phenolic compounds were separated according to polarity by hydrophilic interaction chromatography (HILIC) in the first dimension, whilst reversed-phase liquid chromatography (RP-LC) provided separation according to hydrophobicity in the second dimension. Ultraviolet photodiode array and electrospray ionisation mass spectrometry were used to identify phenolic compounds. Comprehensive HILIC × RP-LC demonstrated its applicability for the analysis of a diverse range of phenolic compounds in unfermented and fermented rooibos samples, in which large qualitative differences in the phenolic composition were established. The combination of these orthogonal separations provided a significant improvement in resolution, as exemplified by practical peak capacities in excess of 2000 and 500 for off-line and on-line methods, respectively.

  12. On the trail of double peak hydrographs

    NASA Astrophysics Data System (ADS)

    Martínez-Carreras, Núria; Hissler, Christophe; Gourdol, Laurent; Klaus, Julian; Juilleret, Jérôme; François Iffly, Jean; McDonnell, Jeffrey J.; Pfister, Laurent

    2016-04-01

    and the plateau) equally contribute to the generation of delayed peaks in double peak hydrographs. We found evidence of catchment storage being a dominant control on the delayed peak activation. The amount of this storage threshold was consistent over a 3-year period. Hillslopes were connected to the stream at low discharge values, whereas the plateau contribution to discharge was significant when storage reached a certain threshold value. The latter seems to trigger the generation of the delayed peak in the double peak events. We also observed a non-linear relationship between storage and discharge, which leads to hysteretic relationships between both variables. During single peak hydrographs and first peaks in double peak hydrographs discharge increases faster and peaks before catchment storage, resulting in counter-clockwise hysteretic loops. This was explained by the fact that these runoff peaks are generated by precipitation falling directly into the stream or near stream locations, and/or by the contribution of water flowing through preferential flowpaths that quickly reached the stream network. When catchment storage exceeded the threshold for the generation of double peak hydrographs, events showed clockwise hysteretic loops. It is the stored water in the catchment that will peak first and consequently generate the delayed peak in the hydrograph as a result of the capacity exceedance of a subsurface storage.

  13. Mathematical model for multicomponent separations on the continuous annular chromatograph

    SciTech Connect

    Bratzler, R.L.; Begovich, J.M.

    1980-12-01

    A model for multicomponent separations on ion exchange columns has been adapted for use in studying the performance of the continuous annular chromatograph. The model accurately predicts solute peak positions in the column effluent and qualitatively predicts trends in solute effluent resolution as a function of increasing bandwidth of the solute feed pulse. The major virtues of the model are its simplicity in terms of the calculations involved and the fact that it incorporates the nonlinear solute-resin binding isotherms common in many ion exchange separations. Because dispersion effects are not accounted for in the model, discrepancies exist between the shapes of the effluent peaks predicted by the model and those determined experimentally.

  14. The gas chromatographic resolution of DL-isovaline

    NASA Technical Reports Server (NTRS)

    Flores, J. J.; Bonner, W. A.; Van Dort, M. A.

    1977-01-01

    Isovaline is of cosmological interest because it is one of the 12 non-protein amino acids which have been isolated from the Murchison meteorite, and unlike the other chiral amino acids in this meteorite, it has no alpha-hydrogen at its asymmetric center and hence cannot racemize by the customary alpha-hydrogen-dependent mechanisms which engender racemization in ordinary amino acids. Experiments were conducted in which a .01 M solution of N-TFA-DL-isovalyl-L-leucine isopropyl ester in nitromethane was injected into the capillary column of a gas chromatograph coupled to a digital electronic integrator-recorder. Efflux times and integrated peak area percents are shown next to each diastereometer peak.

  15. PEAK READING VOLTMETER

    DOEpatents

    Dyer, A.L.

    1958-07-29

    An improvement in peak reading voltmeters is described, which provides for storing an electrical charge representative of the magnitude of a transient voltage pulse and thereafter measuring the stored charge, drawing oniy negligible energy from the storage element. The incoming voltage is rectified and stored in a condenser. The voltage of the capacitor is applied across a piezoelectric crystal between two parallel plates. Amy change in the voltage of the capacitor is reflected in a change in the dielectric constant of the crystal and the capacitance between a second pair of plates affixed to the crystal is altered. The latter capacitor forms part of the frequency determlning circuit of an oscillator and means is provided for indicating the frequency deviation which is a measure of the peak voltage applied to the voltmeter.

  16. INDIAN PEAKS WILDERNESS, COLORADO.

    USGS Publications Warehouse

    Pearson, Robert C.; Speltz, Charles N.

    1984-01-01

    The Indian Peaks Wilderness northwest of Denver is partly within the Colorado Mineral Belt, and the southeast part of it contains all the geologic characteristics associated with the several nearby mining districts. Two deposits have demonstrated mineral resources, one of copper and the other of uranium; both are surrounded by areas with probable potential. Two other areas have probable resource potential for copper, gold, and possibly molydenum. Detailed gravity and magnetic studies in the southeast part of the Indian Peaks Wilderness might detect in the subsurface igneous bodies that may be mineralized. Physical exploration such as drilling would be necessary to determine more precisely the copper resources at the Roaring Fork locality and uranium resources at Wheeler Basin.

  17. PEAK LIMITING AMPLIFIER

    DOEpatents

    Goldsworthy, W.W.; Robinson, J.B.

    1959-03-31

    A peak voltage amplitude limiting system adapted for use with a cascade type amplifier is described. In its detailed aspects, the invention includes an amplifier having at least a first triode tube and a second triode tube, the cathode of the second tube being connected to the anode of the first tube. A peak limiter triode tube has its control grid coupled to thc anode of the second tube and its anode connected to the cathode of the second tube. The operation of the limiter is controlled by a bias voltage source connected to the control grid of the limiter tube and the output of the system is taken from the anode of the second tube.

  18. Gas Chromatographic Determination of Enrivonmentally Significant Pesticides.

    ERIC Educational Resources Information Center

    Rudzinski, Walter E.; Beu, Steve

    1982-01-01

    A chromatographic procedure for analyzing organophosphorus pesticides (such as PCB's, nitrosamines, and phthalate esters) in orange juice is described, including a summary of the method, instrumentation, methodology, results/discussion, and calculations. (JN)

  19. A Versatile, Automatic Chromatographic Column Packing Device

    ERIC Educational Resources Information Center

    Barry, Eugene F.; And Others

    1977-01-01

    Describes an inexpensive apparatus for packing liquid and gas chromatographic columns of high efficiency. Consists of stainless steel support struts, an Automat Getriebmotor, and an associated three-pulley system capable of 10, 30, and 300 rpm. (MLH)

  20. A Quantitative Gas Chromatographic Ethanol Determination.

    ERIC Educational Resources Information Center

    Leary, James J.

    1983-01-01

    Describes a gas chromatographic experiment for the quantitative determination of volume percent ethanol in water ethanol solutions. Background information, procedures, and typical results are included. Accuracy and precision of results are both on the order of two percent. (JN)

  1. Twin Peaks - 3D

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The two hills in the distance, approximately one to two kilometers away, have been dubbed the 'Twin Peaks' and are of great interest to Pathfinder scientists as objects of future study. 3D glasses are necessary to identify surface detail. The white areas on the left hill, called the 'Ski Run' by scientists, may have been formed by hydrologic processes.

    The IMP is a stereo imaging system with color capability provided by 24 selectable filters -- twelve filters per 'eye.

    Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right

  2. Peak-Finding Algorithms.

    PubMed

    Hung, Jui-Hung; Weng, Zhiping

    2017-03-01

    Microarray and next-generation sequencing technologies have greatly expedited the discovery of genomic DNA that can be enriched using various biochemical methods. Chromatin immunoprecipitation (ChIP) is a general method for enriching chromatin fragments that are specifically recognized by an antibody. The resulting DNA fragments can be assayed by microarray (ChIP-chip) or sequencing (ChIP-seq). This introduction focuses on ChIP-seq data analysis. The first step of analyzing ChIP-seq data is identifying regions in the genome that are enriched in a ChIP sample; these regions are called peaks.

  3. Kitt Peak speckle camera

    NASA Technical Reports Server (NTRS)

    Breckinridge, J. B.; Mcalister, H. A.; Robinson, W. G.

    1979-01-01

    The speckle camera in regular use at Kitt Peak National Observatory since 1974 is described in detail. The design of the atmospheric dispersion compensation prisms, the use of film as a recording medium, the accuracy of double star measurements, and the next generation speckle camera are discussed. Photographs of double star speckle patterns with separations from 1.4 sec of arc to 4.7 sec of arc are shown to illustrate the quality of image formation with this camera, the effects of seeing on the patterns, and to illustrate the isoplanatic patch of the atmosphere.

  4. Nanofluidic Size-Exclusion Chromatograph

    NASA Technical Reports Server (NTRS)

    Feldman, Sabrina; Svehla, Danielle; Grunthaner, Frank; Feldman, Jason; Shakkottai, P.

    2004-01-01

    Efforts are under way to develop a nanofluidic size-exclusion chromatograph (SEC), which would be a compact, robust, lightweight instrument for separating molecules of interest according to their sizes and measuring their relative abundances in small samples. About as large as a deck of playing cards, the nanofluidic SEC would serve, in effect, as a laboratory on a chip that would perform the functions of a much larger, conventional, bench-top SEC and ancillary equipment, while consuming much less power and much smaller quantities of reagent and sample materials. Its compactness and low power demand would render it attractive for field applications in which, typically, it would be used to identify and quantitate a broad range of polar and nonpolar organic compounds in soil, ice, and water samples. Size-exclusion chromatography is a special case of high-performance liquid chromatography. In a conventional SEC, a sample plug is driven by pressure along a column packed with silica or polymer beads that contain uniform nanopores. The interstices between, and the pores in, the beads collectively constitute a size-exclusion network. Molecules follow different paths through the size-exclusion network, such that characteristic elution times can be related to sizes of molecules: basically, smaller molecules reach the downstream end of the column after the larger ones do because the smaller ones enter minor pores and stay there for a while, whereas the larger ones do not enter the pores. The volume accessible to molecules gradually diminishes as their size increases. All molecules bigger than a pore size elute together. For most substances, the elution times and sizes of molecules can be correlated directly with molecular weights. Hence, by measuring the flux of molecules arriving at the downstream end as a function of time, one can obtain a liquid mass spectrum for the molecules present in a sample over a broad range of molecular weights.

  5. Size exclusion chromatographic analysis of polyphenol-serum albumin complexes.

    PubMed

    Hatano, Tsutomu; Hori, Mami; Hemingway, Richard W; Yoshida, Takashi

    2003-08-01

    Formation of water-soluble polyphenol-protein complexes was investigated by size-exclusion chromatography (SEC). The combination of (-)-epigallocatechin gallate (EGCG) and bovine serum albumin (BSA), which did not form a precipitate after the solutions were mixed, showed an SEC peak due to complex formation 2-24 h after mixing. Peak size of the complex varied with time, suggesting slow change of the conformation of the protein accompanied by complexation. Formation of the complex was substantiated by ultrafiltration of the mixture; the complex did not pass through a membrane with a 100,000 nominal molecular weight limit (NMWL). The SEC profile varied with the combination of compounds. The peaks due to the complexes showed that the apparent value of the number average molecular weight (M(n)) of the EGCG-BSA complex was 2.8x10(5), while that of a pentagalloylglucose (PGG)-BSA complex was 9.5x10(5) under the conditions used. Dimeric hydrolyzable tannins, oenothein B and cornusiin A, also caused changes in the SEC profile of BSA, although the combinations did not show peaks attributable to formation of such large complexes observed for EGCG and PGG. Procyanidin B3 and (+)-catechin did not cause changes in the SEC profile of BSA. With cytochrome c, EGCG did not show any chromatographic changes.

  6. A discontinuous Galerkin method to solve chromatographic models.

    PubMed

    Javeed, Shumaila; Qamar, Shamsul; Seidel-Morgenstern, Andreas; Warnecke, Gerald

    2011-10-07

    This article proposes a discontinuous Galerkin method for solving model equations describing isothermal non-reactive and reactive chromatography. The models contain a system of convection-diffusion-reaction partial differential equations with dominated convective terms. The suggested method has capability to capture sharp discontinuities and narrow peaks of the elution profiles. The accuracy of the method can be improved by introducing additional nodes in the same solution element and, hence, avoids the expansion of mesh stencils normally encountered in the high order finite volume schemes. Thus, the method can be uniformly applied up to boundary cells without loosing accuracy. The method is robust and well suited for large-scale time-dependent simulations of chromatographic processes where accuracy is highly demanding. Several test problems of isothermal non-reactive and reactive chromatographic processes are presented. The results of the current method are validated against flux-limiting finite volume schemes. The numerical results verify the efficiency and accuracy of the investigated method. The proposed scheme gives more resolved solutions than the high resolution finite volume schemes.

  7. Kitt Peak Observes Comet

    NASA Technical Reports Server (NTRS)

    2005-01-01

    The Kitt Peak National Observatory's 2.1-meter telescope observed comet Tempel 1 on April 11, 2005, when the comet was near its closest approach to the Earth. A pinkish dust jet is visible to the southwest, with the broader neutral gas coma surrounding it. North is up, East is to the left, and the field of view is about 80,000 km (50,000 miles) wide. The Sun was almost directly behind the observer at this time. The red, green and blue bars in the background are stars that moved between the individual images.

    This pseudo-color picture was created by combining three black and white images obtained with different filters. The images were obtained with the HB Narrowband Comet Filters, using CN (3870 A - shown in blue), C2 (5140 A - shown in green) and RC (7128 A - shown in red). The CN and C2 filters capture different gas species (along with the underlying dust) while the RC filter captures just the dust.

  8. Chromatographic resolution of altered forms of protein kinase C

    SciTech Connect

    Ashendel, C.L.; Minor, P.L.; Baudoin, P.A.; Carlos, M.

    1987-05-01

    Rapid chromatographic resolution of protein kinase C (PKC) in extracts of rat brain on DEAE-cellulose yielded two major peaks of activity. These fractions bound phorbol esters with identical affinity and specificity and had similar ratios of PKC to phorbol ester-binding activities. Chicken egg yolk antibodies raised to PKC in the first fraction reacted with 74 to 76 kilodalton peptides in the second fraction. Chromatography of each fraction on hydroxylapatite yielded similar distributions of three PKC isozymes. Rechromatography of the DEAE-cellulose fractions on DEAE-cellulose confirmed that these forms of PKC were not rapidly interconvertible. Results of experiments in which extracts or fractions were incubated with MgATP and phosphatase inhibitors were consistent with elution of dephospho-PKC in the first fraction while the second fraction contained phospho-PKC. If confirmed, this suggests that a substantial fraction of PKC in rat and mouse tissues exists in the phosphorylated form.

  9. Utilizing a constant peak width transform for isothermal gas chromatography.

    PubMed

    Nadeau, Jeremy S; Wilson, Ryan B; Fitz, Brian D; Reed, Jason T; Synovec, Robert E

    2011-06-10

    A computational approach to partially address the general elution problem (GEP), and better visualize, isothermal gas chromatograms is reported. The theoretical computational approach is developed and applied experimentally. We report a high speed temporally increasing boxcar summation (TIBS) transform that, when applied to the raw isothermal GC data, converts the chromatographic data from the initial time domain (in which the peak widths in isothermal GC increase as a function of their retention factors, k), to a data point based domain in which all peaks have the same peak width in terms of number of points in the final data vector, which aides in preprocessing and data analysis, while minimizing data storage size. By applying the TIBS transform, the resulting GC chromatogram (initially collected isothermally), appears with an x-axis point scale as if it were instrumentally collected using a suitable temperature program. A high speed GC isothermal separation with a test mixture containing 10 compounds had a run time of ∼25 s. The peak at a retention factor k ∼0.7 had a peak width of ∼55 ms, while the last eluting peak at k ∼89 (i.e., retention time of ∼22 s) had a peak width of ∼2000 ms. Application of the TIBS transform increased the peak height of the last eluting peak 45-fold, and S/N ∼20-fold. All peaks in the transformed test mixture chromatogram had the width of an unretained peak, in terms of number of data points. A simulated chromatogram at unit resolution, studied using the TIBS transform, provided additional insight into the benefits of the algorithm.

  10. Chromatographic Separation of Glucose and Fructose

    NASA Astrophysics Data System (ADS)

    Kuptsevich, Yu E.; Larionov, Oleg G.; Stal'naya, I. D.; Nakhapetyan, L. A.; Pronin, A. Ya

    1987-03-01

    The structures, mutarotation, and the physicochemical properties of glucose and fructose as well as methods for their separation are examined. Their chromatographic separation on cation exchangers in the calcium-form is discussed in detail. A theory of the formation of complexes of carbohydrates with metal cations is described and the mechanism of the separation of glucose and fructose on cation exchangers in the calcium-form is discussed in detail. Factors influencing the chromatographic separation of glucose and fructose on sulphonic acid cation-exchange resins are also considered. The bibliography includes 138 references.

  11. Peak resolution by semiderivative voltammetry

    SciTech Connect

    Toman, Jeffrey J.; Brown, Steven D.

    1981-08-01

    One of the limitations of dynamic electrochemistry, when used as a quantitative analytical technique, is the resolution of overlapping waves. Approaches used in the past have been either time intensive methods using many blanks, or have relied on many empirical peak parameters. Using an approach based on semidifferential voltammetry, two new techniques have been developed for rapid peak deconvolution. The first technique, NIFITl, is an iterative stripping routine, while the second, BIMFIT, is based on sequential simplex optimization. Both approaches were characterized by deconvolution of synthetic fused peak systems. Subsequently, both were applied to semi-differentiated linear scan voltammograms of Cd2+, Pb2+ and In3+ and to semi-differentiated linear scan anodic stripping voltammograms of Cd2+, ln3+ and Tl+. Deconvolutions were directly characterized by peak height, peak potential and peak halfwidth, in addition to the total squared deviation of the fit peaks from the real fused peaks. Studies of individual peaks as well as of standard additions to fused peaks showed both methods worked well, with excellent deconvolution efficiencies. Synthetic data were totally deconvoluted with peak separation as small as 25 mv, while real systems were deconvoluted with separations below 40 mv. Peak parameters obtained from these deconvolutions allow observations of electrode processes, even in systems containing overlapping peaks.

  12. Gas chromatographic separation of diastereomeric isoprenoids as molecular markers of oil pollution.

    PubMed

    Berthou, F; Friovourt, M P

    1981-12-18

    By means of high-performance glass capillary gas chromatography (GC), diastereomeric isoprenoids were resolved into double peaks. The retention indices on three liquid phases and the mass spectra of the diastereoisomers were almost similar. The leading GC peaks represent the isoprenoids of fossil origin, while the rear peaks correspond to those of recent origin. Computerized gas chromatography-mass spectrometry was used for fingerprinting isoprenoids in different samples. The mass fragmentation patterns were characteristic of the branched alkanes. Hydrocarbon mixtures from four crude oil spills in the sea and from polluted and oil-free oyster tissues were investigated. The relative ratios of n-alkanes/pristane or phytane were shown to be strongly dependent on the chromatographic resolution of the isoprenoid peaks. It is suggested that the double GC peaks in the isoprenoid series are an unmistakable sign of oil pollution.

  13. Economic and safety analysis of unconventional peak regulation on power unit of peak shifting start-stop

    NASA Astrophysics Data System (ADS)

    Cao, X.; Zhao, J. F.; Duan, X. Q.; Jin, Y. A.

    2017-01-01

    Tthe capacity difference of peak regulation between the power gird and the actual demand has become a serious problem considering the growth in the difference between electricity supply and demand. Therefore, peak regulation of power grid needs to be deeply studied. Unconventional peak regulation on unit of peak shifting start-stop is a way that can broaden the range of power regulation, as well as benefit safe operation of the power grid. However, it requires frequent and fast unit start-stop, complex operation, and more staff labor. By carrying out unconventional thermal power unit load test, the start-stop mode of peak auxiliary equipment is studied in this paper, indicating that it has a positive effect on safety and economic of load-peaking operation. The best working conditions of the peak units is found by analysing consumption cost, safety specifications, and life lost of the start-stop peak regulation mode.

  14. VALIDATION OF AN EPA METHOD FOR THE ION CHROMATOGRAPHIC DETERMINATION OF PERCHLORATE IN FERTILIZERS USING A POLYVINYL ALCOHOL GEL RESIN.

    EPA Science Inventory

    This paper summarizes the key points of a joint study between the EPA and Metrohm-Peak, Inc., on the use of polyvinyl alcohol [PVA] columns for the ion chromatographic determination of percholorate in aqueous leachates or solutions of fertilizers. A series of fertilizer samples ...

  15. Numerical Simulation of an Optical Chromatographic Separator

    DTIC Science & Technology

    2009-02-02

    its close relative, Bacillus thuringiensis ," Anal. Chem. 78, 3221-3225 (2006). 10. S. J. Hart, A. Terray, K. L. Kuhn, J. Arnold, and T. A. Leski...Terray, T. A. Leski, J. Arnold, and R. Stroud, "Discovery of a significant optical chromatographic difference between spores of Bacillus anthracis and

  16. 40 CFR 1065.267 - Gas chromatograph.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Gas chromatograph. 1065.267 Section 1065.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Hydrocarbon Measurements § 1065.267 Gas...

  17. 40 CFR 1065.267 - Gas chromatograph.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 33 2011-07-01 2011-07-01 false Gas chromatograph. 1065.267 Section 1065.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Hydrocarbon Measurements § 1065.267 Gas...

  18. Chromatographic methods in the study of autism.

    PubMed

    Żurawicz, Ewa; Kałużna-Czaplińska, Joanna; Rynkowski, Jacek

    2013-10-01

    Research into biomarkers of autism is a new means of medical intervention in this disease. Chromatographic techniques, especially coupled with mass spectrometry, are widely used in determination of biomarkers and assessment of effectiveness of autism therapy owing to their sensitivity and selectivity. Among the chromatographic techniques gas chromatography and liquid chromatography, especially high-performance liquid chromatography, have found application in clinical trials. The high-performance liquid chromatography technique allows an analysis of liquid samples with a wide range of molecules, small and large, providing an opportunity to perform advanced assays within a short time frame. Gas chromatography with the appropriate preparation of samples (gaseous and liquid) and a selection of analysis conditions enables the separation of thermally stable, volatile and non-volatile organic substances in short runtimes. The chromatographic techniques that are currently used in metabolic studies in autism are designed to identify abnormalities in three areas: the metabolism of neurotransmitters, nutritional and metabolic status and manifestations of oxidative stress. This review presents a necessary theoretical introduction and examples of applications of chromatographic studies of disorder markers in autism.

  19. Nano-fabricated size exclusion chromatograph

    NASA Technical Reports Server (NTRS)

    Svehla, D.; Feldman, S.; Feldman, J.; Grunthaner, F.; Shakkottai, P.; dle Castillo, L.; White, V.

    2002-01-01

    This poster describes the development of a nano-fabricated size exclusion chromatograph (nSEC) based on the principle that molecules traveling through a microcolumn containing nano-fabricated features will have characteristics elution times that directly correlate to molecular weight.

  20. Functional chromatographic technique for natural product isolation†

    PubMed Central

    Lau, Eric C.; Mason, Damian J.; Eichhorst, Nicole; Engelder, Pearce; Mesa, Celestina; Kithsiri Wijeratne, E. M.; Gunaherath, G. M. Kamal B.; Leslie Gunatilaka, A. A.

    2015-01-01

    Natural product discovery arises through a unique interplay between chromatographic purification and biological assays. Currently, most techniques used for natural product purification deliver leads without a defined biological action. We now describe a technique, referred to herein as functional chromatography, that deploys biological affinity as the matrix for compound isolation. PMID:25588099

  1. Chromatographic analysis of wheatgrass extracts

    PubMed Central

    Khan, Masood Shah; Parveen, Rabea; Mishra, Kshipra; Tulsawani, Rajkumar; Ahmad, Sayeed

    2015-01-01

    Aim: Wheatgrass (WG) is the shoot of Triticum aestivum Linn. belongs to the family Gramineae, and possess high chlorophyll content and essential vitamins, minerals, vital enzymes, amino acids, dietary fibers etc., It has been shown to possess anti-cancer, anti-ulcer, antioxidant, and anti-arthritic activity due to the presence of biologically active compounds, and minerals. Therefore, in the present study, high-performance thin layer chromatography (HPTLC), and high-performance liquid chromatography (HPLC) methods for qualitative and quantitative analysis have been proposed, which will help in quality evaluation of wheat grass extract. Materials and Methods: Samples for analysis were prepared in methanol and water simply by sonication. These were applied on pre-coated silica plate and chromatograms were developed using toluene: Ethyl acetate: Formic acid. HPLC analysis was done on Waters HPLC system using water, methanol, and acetonitrile as mobile phase. Merck C18 column has been used. Results: HPTLC finger printing of alcoholic extracts of WG was carried out and found 10–11 spots at different wavelengths 254, 366, and 435 nm. HPLC fingerprinting produced 22 peaks at 256 nm. Quantitative HPTLC analysis was done to determine the gallic acid content, and was found to be 0.077% w/w in aqueous extract. By HPLC, the content of gallic acid and rutin was found to be 0.07%, and 0.04% w/w in aqueous extract of WG. Conclusion: The developed HPLC and HPTLC fingerprinting method can be used for the quality control, and standardization of WG and its extracts used as nutritional supplement. PMID:26681880

  2. Method to fabricate silicon chromatographic column comprising fluid ports

    DOEpatents

    Manginell, Ronald P.; Frye-Mason, Gregory C.; Heller, Edwin J.; Adkins, Douglas R.

    2004-03-02

    A new method for fabricating a silicon chromatographic column comprising through-substrate fluid ports has been developed. This new method enables the fabrication of multi-layer interconnected stacks of silicon chromatographic columns.

  3. A Small-Scale Low-Cost Gas Chromatograph

    ERIC Educational Resources Information Center

    Gros, Natasa; Vrtacnik, Margareta

    2005-01-01

    The design and application of a small-scale portable gas chromatograph for learning of the basic concepts of chromatography is described. The apparatus consists of two basic separable units, which includes a chromatographic unit and an electronic unit.

  4. Method for the chromatographic separation of cations from aqueous samples

    DOEpatents

    Horwitz, E.P.; Chiarizia, R.; Dietz, M.L.

    1997-07-29

    An extraction chromatographic material is described for extracting metal cations from a liquid stream. The extraction chromatographic material is prepared by adsorbing a diesterified methanediphosphonic acid on an inert particulate support. 7 figs.

  5. Tadpole toxicity prediction using chromatographic systems.

    PubMed

    Fernández-Pumarega, Alejandro; Amézqueta, Susana; Fuguet, Elisabet; Rosés, Martí

    2015-10-30

    Toxicity has been emulated in tadpole species through chromatographic systems. The parameter studied to evaluate the non-specific toxicity of a compound is the narcosis concentration (Cnar), which is defined as the concentration needed for the immobilization of the organism. Because experimental investigation with animals is lengthy, costly, technically difficult, and ethically questionable, there is a great interest in developing surrogate physicochemical systems able to emulate biological systems to obtain the same information in a faster, more economic, and easier manner. In order to see which chromatographic systems would be able to emulate tadpole narcosis, both, tadpole narcosis data and data in several chromatographic and electrophoretic systems, were fitted to a linear solvation energy relationship (LSER) model. Thus, by comparison of the models it was possible to see which of the chromatographic systems were more similar to the biological one. The physicochemical systems that best emulate tadpole narcosis were an HPLC system based on an immobilized artificial membrane (IAM) column, and two micellar electrokinetic chromatography (MEKC) systems based on sodium taurocholate (STC) and a mixture of sodium dodecylsulphate (SDS) and Brij 35 as surfactants. A system based on a RP18 HPLC column also was selected for comparison because it is a common column in most analytical laboratories. To establish the models, a set of compounds with known Cnar values were analyzed in the chromatographic, and electrophoretic selected systems and, then, the retention factor (k) was correlated to the concentration of narcosis. Statistics showed that the system based on STC micelles was the best to emulate toxicity in tadpoles. The robustness and predictive ability of the developed models were validated.

  6. Micro-column plasma emission liquid chromatograph

    DOEpatents

    Gay, Don D.

    1984-01-01

    In a direct current plasma emission spectrometer for use in combination with a micro-column liquid chromatograph, an improved plasma source unit. The plasma source unit includes a quartz capillary tube having an inlet means, outlet off gas means and a pair of spaced electrodes defining a plasma region in the tube. The inlet means is connected to and adapted to receive eluant of the liquid chromatograph along with a stream of plasma-forming gas. There is an opening through the wall of the capillary tube penetrating into the plasma region. A soft glass capillary light pipe is disposed at the opening, is connected to the spectrometer, and is adapted to transmit light passing from the plasma region to the spectrometer. There is also a source of electromotive force connected to the electrodes sufficient to initiate and sustain a plasma in the plasma region of the tube.

  7. Chromatographic purification of highly active yeast ribosomes.

    PubMed

    Meskauskas, Arturas; Leshin, Jonathan A; Dinman, Jonathan D

    2011-10-24

    Eukaryotic ribosomes are much more labile as compared to their eubacterial and archael counterparts, thus posing a significant challenge to researchers. Particularly troublesome is the fact that lysis of cells releases a large number of proteases and nucleases which can degrade ribosomes. Thus, it is important to separate ribosomes from these enzymes as quickly as possible. Unfortunately, conventional differential ultracentrifugation methods leaves ribosomes exposed to these enzymes for unacceptably long periods of time, impacting their structural integrity and functionality. To address this problem, we utilize a chromatographic method using a cysteine charged Sulfolink resin. This simple and rapid application significantly reduces co-purifying proteolytic and nucleolytic activities, producing high yields of intact, highly biochemically active yeast ribosomes. We suggest that this method should also be applicable to mammalian ribosomes. The simplicity of the method, and the enhanced purity and activity of chromatographically purified ribosome represents a significant technical advancement for the study of eukaryotic ribosomes.

  8. Nano-fabricated size exclusion chromatograph

    NASA Technical Reports Server (NTRS)

    Svehla, D.; Feldman, S.; Feldman, J.; Grunthaner, F.; Shakkottai, P.; Castillo, L. del; White, V.

    2002-01-01

    This paper describes the development of a nano-fabricated size exclusion chromatograph (nSEC) based on the principle that molecules traveling through amicrocolumn containing nano-fabricated features will have characteristic elution times that directly correlate to molecular weight. Compared to conventional size exclusion chromatography, the nSEC offers greater control over the size exclusion process; mass fabrication; integration of the separation column with associated valves, pumps, and detectors; and dramatic reductions in instrument mass and power requirements.

  9. Exact peak compression factor in linear gradient elution. I. Theory.

    PubMed

    Gritti, Fabrice; Guiochon, Georges

    2008-11-28

    The only existing expression for the peak compression factor in linear gradient elution chromatography assumes that the linear-solvent-strength model (LSSM) applies to the retention of the compound studied, that the column efficiency is independent of the mobile phase composition, and that, during gradient elution, the relative retention factor of a compound inside its band varies linearly with the distance from the band center. Because the retention factors of many analytes in reversed-phase liquid chromatography do not rigorously follow the LSSM, we extend the theoretical approach of Poppe et al. to the prediction of peak compression factors in linear gradient elution chromatography for any retention model, when column efficiency varies with the mobile phase composition. Only the contribution of the chromatographic column to the peak compression was taken into account, the contribution of the dwell volume being neglected. A second restriction is the linearity of the relative retention factor as a function of the position along the band width inside the column. These constraints could be the sources for the difference observed between experimental and theoretical values of peak compression factors. When the retention factor varies steeply with the mobile phase composition, such as with proteins or large peptides in RP-HPLC, it is found that the thermodynamic compression term, which tends to sharpen the peak, is coupled with the column dispersion term, which tends to broaden the peak. This coupling term acts as an apparent dispersion term, contributing to broaden the peak. This result is consistent with the measurements of peak compression factors found in the literature.

  10. Chromatographic fingerprint similarity analysis for pollutant source identification.

    PubMed

    Xie, Juan-Ping; Ni, Hong-Gang

    2015-12-01

    In the present study, a similarity analysis method was proposed to evaluate the source-sink relationships among environmental media for polybrominated diphenyl ethers (PBDEs), which were taken as the representative contaminants. Chromatographic fingerprint analysis has been widely used in the fields of natural products chemistry and forensic chemistry, but its application to environmental science has been limited. We established a library of various sources of media containing contaminants (e.g., plastics), recognizing that the establishment of a more comprehensive library allows for a better understanding of the sources of contamination. We then compared an environmental complex mixture (e.g., sediment, soil) with the profiles in the library. These comparisons could be used as the first step in source tracking. The cosine similarities between plastic and soil or sediment ranged from 0.53 to 0.68, suggesting that plastic in electronic waste is an important source of PBDEs in the environment, but it is not the only source. A similarity analysis between soil and sediment indicated that they have a source-sink relationship. Generally, the similarity analysis method can encompass more relevant information of complex mixtures in the environment than a profile-based approach that only focuses on target pollutants. There is an inherent advantage to creating a data matrix containing all peaks and their relative levels after matching the peaks based on retention times and peak areas. This data matrix can be used for source identification via a similarity analysis without quantitative or qualitative analysis of all chemicals in a sample.

  11. Superheated water as chromatographic eluent for parabens separation on octadecyl coated zirconia stationary phase.

    PubMed

    Dugo, Paola; Buonasera, Katia; Crupi, Maria Lucia; Cacciola, Francesco; Dugo, Giovanni; Mondello, Luigi

    2007-05-01

    In this study, the use of pure water at superheated temperatures, between 100 and 200 degrees C, as a mobile phase for RP separation is explored. Instrumental parameters, such as temperature, flow rate, preheating and cooling, have shown significant effects on the quality of the chromatographic peaks. The properties of superheated water as an eluent were investigated by observing the chromatographic behaviour of four parabens on a carbon-clad zirconia (ZR) phase with covalently bonded octadecyl groups. Results were compared with those obtained at 30 degrees C on a silica-based phase with octadecyl groups, using water and ACN as mobile phase. The optimized method was finally applied to analyse parabens in a commercial body cream.

  12. Peak Oil: Diverging Discursive Pipelines

    NASA Astrophysics Data System (ADS)

    Doctor, Jeff

    Peak oil is the claimed moment in time when global oil production reaches its maximum rate and henceforth forever declines. It is highly controversial as to whether or not peak oil represents cause for serious concern. My thesis explores how this controversy unfolds but brackets the ontological status of the reality indexed by the peakoil concept. I do not choose a side in the debate; I look at the debate itself. I examine the energy outlook documents of ExxonMobil, Shell, BP, Chevron, Total and the International Energy Agency (IEA) as well as academic articles and documentaries. Through an in-depth analysis of peak-oil controversy via tenets of actor-network theory (ANT), I show that what is at stake are competing framings of reality itself, which must be understood when engaging with the contentious idea of peak oil.

  13. Flu Season Starting to Peak

    MedlinePlus

    ... page: https://medlineplus.gov/news/fullstory_162917.html Flu Season Starting to Peak More severe strain of ... 6, 2017 FRIDAY, Jan. 6, 2017 (HealthDay News) -- Flu season is in full swing and it's starting ...

  14. Comparison among three anion exchange chromatographic supports to capture erythropoietin from cell culture supernatant.

    PubMed

    Hernández, Lourdes; Stewart, Diobel; Zumalacárregui, Lourdes; Amaro, Daniel

    2015-06-01

    Affinity and ion exchange conventional chromatography have been used to capture erythropoietin (EPO) from mammalian cell culture supernatant. Currently, chromatographic adsorbent perfusion is available, however a limited number of applications have been found in the literature. In this work, three anion exchange chromatographic supports (gel, membrane and monolithic) were evaluated in the capture step of the recombinant erythropoietin purification process. The influences of load and flow rate on each support performance were analyzed. Also the purity of the EPO molecules was determined. A productivity analysis, as a decision tool for larger scale implementation, was done. As a conclusion, the evaluated supports are technically suitable to capture EPO with adequate recovery and good purity. However, the monolithic column admits high operating velocity, showing the highest adsorption capacity and productivity.

  15. Allyl-silica Hybrid Monoliths For Chromatographic Application

    NASA Astrophysics Data System (ADS)

    Guo, Wenjuan

    procedure. Important parameters that influence the morphology of the allyl-silica hybrid material, such as the type and monomer ratio of silanes, the amount of porogenic material, the hydrolysis reaction time, the gelation temperature, the water to silicon ratio has been optimized. In addition, factors that affect the volume shrinkage including the fourth precursor, capillary filling temperature, the aging temperature and aging time and the fine tuning of PEG amount have been discussed in details. The pH stability of allyl-silica hybrid (III) monolithic column has been compared with that of TMOS monolithic column and allyl-silica hybrid (I) monolithic column. Details of the preparation, characterization and the initial chromatographic performance of the allyl-silica hybrid monolith are reported. Good peak asymmetry is obtained for the separation of basic analytes. Allyl-functionalized silica hybrid monolithic structures have also been synthesized for use in CEC, nano-LC and HPLC. The monolithic material is synthesized in a "one pot" reaction approach that provides the functionalized silica support material containing accessible allyl organic groups. The allyl and methyl moieties at the surface with significantly hydrophobic characteristics, can be used as stationary phase directly and provide chromatographic selectivity. Capillary liquid chromatography (CLC) and capillary electrochromatography (CEC) were used to demonstrate the chromatographic kinetics of the hybrid monolith. Evaluation of the stationary phase for HPLC was performed using alkylbenzene as model compounds.

  16. A novel strategy for quantitative analysis of the formulated complex system using chromatographic fingerprints combined with some chemometric techniques.

    PubMed

    Zhong, Xuan; Yan, Jun; Li, Yan-Chun; Kong, Bo; Lu, Hong-Bing; Liang, Yi-Zeng

    2014-11-28

    In this work, a novel strategy based on chromatographic fingerprints and some chemometric techniques is proposed for quantitative analysis of the formulated complex system. Here, the formulated complex system means a formulated type of complicated analytical system containing more than one kind of raw material under some concentration composition according to a certain formula. The strategy is elaborated by an example of quantitative determination of mixtures consist of three essential oils. Three key steps of the strategy are as follows: (1) remove baselines of the chromatograms; (2) align retention time; (3) conduct quantitative analysis using multivariate regression with entire chromatographic profiles. Through the determination of concentration compositions of nine mixtures arranged by uniform design, the feasibility of the proposed strategy is validated and the factors that influence the quantitative result are also discussed. This strategy is proved to be viable and the validation indicates that quantitative result obtained using this strategy mainly depends on the efficiency of the alignment method as well as chromatographic peak shape of the chromatograms. Previously, chromatographic fingerprints were only used for identification and/or recognition of some products. This work demonstrates that with the assistance of some effective chemometric techniques, chromatographic fingerprints are also potential and promising in solving quantitative problems of complex analytical systems.

  17. Comparison of chromatographic ion-exchange resins V. Strong and weak cation-exchange resins.

    PubMed

    Staby, Arne; Jacobsen, Jan H; Hansen, Ronni G; Bruus, Ulla K; Jensen, Inge Holm

    2006-06-23

    Strong and weak cation-exchangers were compared for a number of chromatographic parameters, i.e. pH dependence, efficiency, binding strength, particle size distribution, static and dynamic capacity, and scanning electron microscopy (SEM) pictures. Chromatographic resins investigated were Fractogel EMD SO3- (M), Fractogel EMD SE Hicap (M), Fractogel EMD COO- (M), MacroPrep 25S, MacroPrep High S, MacroPrep CM, CM HyperZ, and Matrex Cellufine C-500. Testing was done with three proteins: Anti-FVII Mab (IgG), aprotinin, and lysozyme. For lysozyme and aprotinin with pI above experimental pH, dependence of pH on retention was generally low, though some pronounced decrease of retention with increasing pH was observed for CM HyperZ. For Anti-FVII Mab with pI<7.5, binding was observed on several resins at pH 7.5. Efficiency results present the expected trend of increasing dependence of plate height as a function of increasing flow rate, and the highest flow dependence was observed for Fractogel EMD COO-. Particle size distribution was determined by two independent methods, coulter counting and SEM pictures, with fair agreement. Binding strength data of cation-exchange resins as a function of ionic strength depends on the protein, but binding and elution at high salt concentration may in general be performed with MacroPrep resins. Comparison of dynamic capacity data at 10% break-through and static capacity measurements shows that a very diverse utilization of approximately 25-90% of the total available capacity is employed during chromatographic operation. The effect of competitive binding from yeast fermentation components on dynamic binding capacity of aprotinin was studied showing a significant decrease in binding capacity. Sepharose FF, Toyopearl 650 M, and Ceramic HyperD F strong and weak cation-exchange resins were included in this study. Resins with good pure aprotinin capacity also performed well for aprotinin in fermentation broth, but the highest relative capacity

  18. High pressure liquid chromatographic gradient mixer

    DOEpatents

    Daughton, Christian G.; Sakaji, Richard H.

    1985-01-01

    A gradient mixer which effects the continuous mixing of any two miscible solvents without excessive decay or dispersion of the resultant isocratic effluent or of a linear or exponential gradient. The two solvents are fed under low or high pressure by means of two high performance liquid chromatographic pumps. The mixer comprises a series of ultra-low dead volume stainless steel tubes and low dead volume chambers. The two solvent streams impinge head-on at high fluxes. This initial nonhomogeneous mixture is then passed through a chamber packed with spirally-wound wires which cause turbulent mixing thereby homogenizing the mixture with minimum "band-broadening".

  19. Hand-held multiple system gas chromatograph

    DOEpatents

    Yu, Conrad M.

    2001-01-01

    A multiple parallel hand-held gas chromatograph (GC) system which includes several independent GCs. Each independent GC has its own injector, separation column, detector and oven and the GCs are mounted in a light weight hand-held assembly. Each GC operates independently and simultaneously. Because of different coatings in different separation columns, different retention times for the same gas will be measured. Thus, for a GC system with multiple parallel GCs, the system can measure, in a short period, different retention times and provide a cross-reference in the determination of the measured gas and to become a two-dimensional system for direct field use.

  20. High-pressure liquid chromatographic gradient mixer

    DOEpatents

    Daughton, C.G.; Sakaji, R.H.

    1982-09-08

    A gradient mixer effects the continuous mixing of any two miscible solvents without excessive decay or dispersion of the resultant isocratic effluent or of a linear or exponential gradient. The two solvents are fed under low or high pressure by means of two high performance liquid chromatographic pumps. The mixer comprises a series of ultra-low dead volume stainless steel tubes and low dead volume chambers. The two solvent streams impinge head-on at high fluxes. This initial nonhomogeneous mixture is then passed through a chamber packed with spirally-wound wires which cause turbulent mixing thereby homogenizing the mixture with minimum band-broadening.

  1. Packed multi-channels for parallel chromatographic separations in microchips.

    PubMed

    Nagy, Andrea; Gaspar, Attila

    2013-08-23

    Here we report on a simple method to fabricate microfluidic chip incorporating multi-channel systems packed by conventional chromatographic particles without the use of frits. The retaining effectivities of different bottlenecks created in the channels were studied. For the parallel multi-channel chromatographic separations several channel patterns were designed. The obtained multipackings were applied for parallel separations of dyes. The implementation of several chromatographic separation units in microscopic size makes possible faster and high throughput separations.

  2. Identification and phylogeny of Arabian snakes: Comparison of venom chromatographic profiles versus 16S rRNA gene sequences

    PubMed Central

    Al Asmari, Abdulrahman; Manthiri, Rajamohammed Abbas; Khan, Haseeb Ahmad

    2014-01-01

    Identification of snake species is important for various reasons including the emergency treatment of snake bite victims. We present a simple method for identification of six snake species using the gel filtration chromatographic profiles of their venoms. The venoms of Echis coloratus, Echis pyramidum, Cerastes gasperettii, Bitis arietans, Naja arabica, and Walterinnesia aegyptia were milked, lyophilized, diluted and centrifuged to separate the mucus from the venom. The clear supernatants were filtered and chromatographed on fast protein liquid chromatography (FPLC). We obtained the 16S rRNA gene sequences of the above species and performed phylogenetic analysis using the neighbor-joining method. The chromatograms of venoms from different snake species showed peculiar patterns based on the number and location of peaks. The dendrograms generated from similarity matrix based on the presence/absence of particular chromatographic peaks clearly differentiated Elapids from Viperids. Molecular cladistics using 16S rRNA gene sequences resulted in jumping clades while separating the members of these two families. These findings suggest that chromatographic profiles of snake venoms may provide a simple and reproducible chemical fingerprinting method for quick identification of snake species. However, the validation of this methodology requires further studies on large number of specimens from within and across species. PMID:25313278

  3. Identification and phylogeny of Arabian snakes: Comparison of venom chromatographic profiles versus 16S rRNA gene sequences.

    PubMed

    Al Asmari, Abdulrahman; Manthiri, Rajamohammed Abbas; Khan, Haseeb Ahmad

    2014-11-01

    Identification of snake species is important for various reasons including the emergency treatment of snake bite victims. We present a simple method for identification of six snake species using the gel filtration chromatographic profiles of their venoms. The venoms of Echis coloratus, Echis pyramidum, Cerastes gasperettii, Bitis arietans, Naja arabica, and Walterinnesia aegyptia were milked, lyophilized, diluted and centrifuged to separate the mucus from the venom. The clear supernatants were filtered and chromatographed on fast protein liquid chromatography (FPLC). We obtained the 16S rRNA gene sequences of the above species and performed phylogenetic analysis using the neighbor-joining method. The chromatograms of venoms from different snake species showed peculiar patterns based on the number and location of peaks. The dendrograms generated from similarity matrix based on the presence/absence of particular chromatographic peaks clearly differentiated Elapids from Viperids. Molecular cladistics using 16S rRNA gene sequences resulted in jumping clades while separating the members of these two families. These findings suggest that chromatographic profiles of snake venoms may provide a simple and reproducible chemical fingerprinting method for quick identification of snake species. However, the validation of this methodology requires further studies on large number of specimens from within and across species.

  4. Two classes of speculative peaks

    NASA Astrophysics Data System (ADS)

    Roehner, Bertrand M.

    2001-10-01

    Speculation not only occurs in financial markets but also in numerous other markets, e.g. commodities, real estate, collectibles, and so on. Such speculative movements result in price peaks which share many common characteristics: same order of magnitude of duration with respect to amplitude, same shape (the so-called sharp-peak pattern). Such similarities suggest (at least as a first approximation) a common speculative behavior. However, a closer examination shows that in fact there are (at least) two distinct classes of speculative peaks. For the first, referred to as class U, (i) the amplitude of the peak is negatively correlated with the price at the start of the peak (ii) the ensemble coefficient of variation exhibits a trough. Opposite results are observed for the second class that we refer to as class S. Once these empirical observations have been made we try to understand how they should be interpreted. First, we show that the two properties are in fact related in the sense that the second is a consequence of the first. Secondly, by listing a number of cases belonging to each class we observe that the markets in the S-class offer collection of items from which investors can select those they prefer. On the contrary, U-markets consist of undifferentiated products for which a selection cannot be made in the same way. All prices considered in the paper are real (i.e., deflated) prices.

  5. High performance hand-held gas chromatograph

    SciTech Connect

    Yu, C.M.

    1998-04-28

    The Microtechnology Center of Lawrence Livermore National Laboratory has developed a high performance hand-held, real time detection gas chromatograph (HHGC) by Micro-Electro-Mechanical-System (MEMS) technology. The total weight of this hand-held gas chromatograph is about five lbs., with a physical size of 8{close_quotes} x 5{close_quotes} x 3{close_quotes} including carrier gas and battery. It consumes about 12 watts of electrical power with a response time on the order of one to two minutes. This HHGC has an average effective theoretical plate of about 40k. Presently, its sensitivity is limited by its thermal sensitive detector at PPM. Like a conventional G.C., this HHGC consists mainly of three major components: (1) the sample injector, (2) the column, and (3) the detector with related electronics. The present HHGC injector is a modified version of the conventional injector. Its separation column is fabricated completely on silicon wafers by means of MEMS technology. This separation column has a circular cross section with a diameter of 100 pm. The detector developed for this hand-held GC is a thermal conductivity detector fabricated on a silicon nitride window by MEMS technology. A normal Wheatstone bridge is used. The signal is fed into a PC and displayed through LabView software.

  6. Gas chromatographic analysis of volatiles in fluid and gas inclusions

    USGS Publications Warehouse

    Andrawes, F.; Holzer, G.; Roedder, E.; Gibson, E.K.; Oro, J.

    1984-01-01

    Most geological samples and some synthetic materials contain fluid inclusions. These inclusions preserve for us tiny samples of the liquid and/or the gas phase that was present during formation, although in some cases they may have undergone significant changes from the original material. Studies of the current composition of the inclusions provide data on both the original composition and the change since trapping. These inclusions are seldom larger than 1 millimeter in diameter. The composition varies from a single major compound (e.g., water) in a single phase to a very complex mixture in one or more phases. The concentration of some of the compounds present may be at trace levels. We present here some analyses of inclusions in a variety of geological samples, including diamonds. We used a sample crusher and a gas chromatography-mass spectrometry (GC-MS) system to analyze for organic and inorganic volatiles present as major to trace constituents in inclusions. The crusher is a hardened stainless-steel piston cylinder apparatus with tungsten carbide crusing surfaces, and is operated in a pure helium atmosphere at a controlled temperature. Samples ranging from 1 mg to 1 g were crushed and the released volatiles were analyzed using multi-chromatographic columns and detectors, including the sensitive helium ionization detector. Identification of the GC peaks was carried out by GC-MS. This combination of procedures has been shown to provide geochemically useful information on the process involved in the history of the samples analyzed. ?? 1984.

  7. Comparison of three advanced chromatographic techniques for cannabis identification.

    PubMed

    Debruyne, D; Albessard, F; Bigot, M C; Moulin, M

    1994-01-01

    The development of chromatography technology, with the increasing availability of easier-to-use mass spectrometers combined with gas chromatography (GC), the use of diode-array or programmable variable-wavelength ultraviolet absorption detectors in conjunction with high-performance liquid chromatography (HPLC), and the availability of scanners capable of reading thin-layer chromatography (TLC) plates in the ultraviolet and visible regions, has made for easier, quicker and more positive identification of cannabis samples that standard analytical laboratories are occasionally required to undertake in the effort to combat drug addiction. At laboratories that do not possess the technique of GC combined with mass spectrometry, which provides an irrefutable identification, the following procedure involving HPLC or TLC techniques may be used: identification of the chromatographic peaks corresponding to each of the three main cannabis constituents-cannabidiol (CBD), delta-9-tetrahydrocannabinol (delta-9-THC) and cannabinol (CBN)-by comparison with published data in conjunction with a specific absorption spectrum for each of those constituents obtained between 200 and 300 nm. The collection of the fractions corresponding to the three major cannabinoids at the HPLC system outlet and the cross-checking of their identity in the GC process with flame ionization detection can further corroborate the identification and minimize possible errors due to interference.

  8. Peak finding using biorthogonal wavelets

    SciTech Connect

    Tan, C.Y.

    2000-02-01

    The authors show in this paper how they can find the peaks in the input data if the underlying signal is a sum of Lorentzians. In order to project the data into a space of Lorentzian like functions, they show explicitly the construction of scaling functions which look like Lorentzians. From this construction, they can calculate the biorthogonal filter coefficients for both the analysis and synthesis functions. They then compare their biorthogonal wavelets to the FBI (Federal Bureau of Investigations) wavelets when used for peak finding in noisy data. They will show that in this instance, their filters perform much better than the FBI wavelets.

  9. How to use your peak flow meter

    MedlinePlus

    ... get your child used to them. Find Your Personal Best To find your personal best peak flow ... peak flow meter; Bronchial asthma - peak flow meter Images How to measure peak flow References Durrani SR, ...

  10. Flavonoid content and antioxidant capacity of spinach genotypes determined by high-performance liquid chromatography/mass spectrometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Flavonoids in different spinach genotypes were separated, identified, and quantified by a high-performance liquid chromatographic method with photodiode array and mass spectrometric detection. The antioxidant capacities of the genotypes were also measured using two antioxidant assays - oxygen radica...

  11. Peak Stress Testing Protocol Framework

    EPA Science Inventory

    Treatment of peak flows during wet weather is a common challenge across the country for municipal wastewater utilities with separate and/or combined sewer systems. Increases in wastewater flow resulting from infiltration and inflow (I/I) during wet weather events can result in op...

  12. Hubbert's Peak -- A Physicist's View

    NASA Astrophysics Data System (ADS)

    McDonald, Richard

    2011-04-01

    Oil, as used in agriculture and transportation, is the lifeblood of modern society. It is finite in quantity and will someday be exhausted. In 1956, Hubbert proposed a theory of resource production and applied it successfully to predict peak U.S. oil production in 1970. Bartlett extended this work in publications and lectures on the finite nature of oil and its production peak and depletion. Both Hubbert and Bartlett place peak world oil production at a similar time, essentially now. Central to these analyses are estimates of total ``oil in place'' obtained from engineering studies of oil reservoirs as this quantity determines the area under the Hubbert's Peak. Knowing the production history and the total oil in place allows us to make estimates of reserves, and therefore future oil availability. We will then examine reserves data for various countries, in particular OPEC countries, and see if these data tell us anything about the future availability of oil. Finally, we will comment on synthetic oil and the possibility of carbon-neutral synthetic oil for a sustainable future.

  13. Chromatographic Separation and NMR An Integrated Approach in Pharmaceutical Development.

    PubMed

    Gonnella, Nina C

    2012-01-01

    Over the past 10 years, major improvements in the performance of LC-NMR have been realized. The addition of postcolumn SPE, advances in probe technology including cryogenic probes and microcoil probes, improved solvent suppression pulse sequences, and shielded magnets with better homogeneity have all contributed to rapid advancements in this technology. Application of LC-NMR to problems in pharmaceutical development has had a major impact on structure elucidation studies. LC-NMR has been successfully applied to determine the structures of degradation products, impurities, mixtures of compounds, and metabolites. Use of stop flow techniques with LC-NMR experiments has been a critical means of identifying unstable compounds and studying conformational kinetics. The integration of SPE as an intermediate step between the LC unit and the NMR spectrometer has vastly improved the power of the hyphenated technique in trace analysis applications. Online postcolumn enrichment of chromatographic peaks by SPE dramatically reduces the NMR acquisition times by allowing repeated injections to be trapped onto the same cartridge or different cartridges. Because protonated solvents can be easily removed with a drying procedure, solvents and buffers may be freely chosen for maximizing chromatographic separation without compromising NMR spectral quality. The compound of interest may then be eluted from an SPE cartridge using deuterated organic solvent, which helps to reduce dynamic range issues. When combined with cryogenically cooled microcapillary probes, the sensitivity of the NMR signal increases about 10-fold over conventional room temperature probes, enabling full structure characterization at the microgram level. Heteronuclear experiments with concentrations previously only possible in a limited number of cases have now become standard experiments. The availability of HSQC and HMBC experiments and microcoil/cryogenic technology opens the possibility of using LC-(SPE) NMR for the

  14. Fast gas chromatographic separation of biodiesel.

    SciTech Connect

    Pauls, R. E.

    2011-05-01

    A high-speed gas chromatographic method has been developed to determine the FAME distribution of B100 biodiesel. The capillary column used in this work has dimensions of 20 m x 0.100 mm and is coated with a polyethylene glycol film. Analysis times are typically on the order of 4-5 min depending upon the composition of the B100. The application of this method to a variety of vegetable and animal derived B100 is demonstrated. Quantitative results obtained with this method were in close agreement with those obtained by a more conventional approach on a 100 m column. The method, coupled with solid-phase extraction, was also found suitable to determine the B100 content of biodiesel-diesel blends.

  15. Detection system for a gas chromatograph

    DOEpatents

    Hayes, John M.; Small, Gerald J.

    1984-01-01

    A method and apparatus are described for the quantitative analysis of vaporizable compounds, and in particular of polycyclic aromatic hydrocarbons which may be induced to fluoresce. The sample to be analyzed is injected into a gas chromatography column and is eluted through a narrow orifice into a vacuum chamber. The free expansion of the eluted sample into the vacuum chamber creates a supersonic molecular beam in which the sample molecules are cooled to the extent that the excited vibrational and rotational levels are substantially depopulated. The cooled molecules, when induced to fluoresce by laser excitation, give greatly simplified spectra suitable for analytical purposes. The laser induced fluorimetry provides great selectivity, and the gas chromatograph provides quantitative transfer of the sample to the molecular beam.

  16. Liquid chromatographic determination of melamine in beverages.

    PubMed

    Ishiwata, H; Inoue, T; Yamazaki, T; Yoshihira, K

    1987-01-01

    A liquid chromatographic method is described for the determination of melamine in beverages. Melamine is separated by column chromatography using cation and anion exchange resin and determined by ion-pair liquid chromatography using an ODS column and a mixture of acetonitrile and 0.05M phosphate buffer (pH 3.0) containing 0.005M sodium 1-laurylsulfate (1 + 4, v/v) as mobile phase. Recoveries of melamine ranged between 90.3 +/- 7.8 and 102.1 +/- 5.6% at levels of 0.6 to 2.4 ppm in 4 kinds of beverages. The quantitation limit was 2.5 micrograms melamine in 50 mL beverage. The method was applied to the migration test of melamine from melamine-formaldehyde resin products to the beverages.

  17. Gas Chromatographic Detectors for Exobiology Flight Experiments

    NASA Technical Reports Server (NTRS)

    Kojiro, Daniel R.; Humphry, Donald E.; Takeuchi, Nori; Chang, Sherwood (Technical Monitor)

    1997-01-01

    Exobiology flight experiments require highly sensitive instrumentation for in situ chemical analysis of the volatile chemical species that occur in the atmospheres and surfaces of various bodies within the solar system. The complex mixtures encountered place a heavy burden on the analytical instrumentation to detect and identify all species present. Future missions to Mars', comets, or planetary moons such as Europa, will perform experiments with complex analyses. In addition, instrumentation for such missions must perform under severely restricted conditions with limited resources. To meet these analytical requirements, improved methods and highly sensitive yet smaller instruments must continually be developed with increasingly greater capabilities. We describe here efforts to achieve this objective, for past and future missions, through the development of new or the improvement of existing sensitive, miniaturized gas chromatographic detectors.

  18. Interface for liquid chromatograph-mass spectrometer

    DOEpatents

    Andresen, B.D.; Fought, E.R.

    1989-09-19

    A moving belt interface is described for real-time, high-performance liquid chromatograph (HPLC)/mass spectrometer (MS) analysis which strips away the HPLC solvent as it emerges from the end of the HPLC column and leaves a residue suitable for mass-spectral analysis. The interface includes a portable, stand-alone apparatus having a plural stage vacuum station, a continuous ribbon or belt, a drive train magnetically coupled to an external drive motor, a calibrated HPLC delivery system, a heated probe tip and means located adjacent the probe tip for direct ionization of the residue on the belt. The interface is also capable of being readily adapted to fit any mass spectrometer. 8 figs.

  19. Interface for liquid chromatograph-mass spectrometer

    DOEpatents

    Andresen, Brian D.; Fought, Eric R.

    1989-01-01

    A moving belt interface for real-time, high-performance liquid chromatograph (HPLC)/mass spectrometer (MS) analysis which strips away the HPLC solvent as it emerges from the end of the HPLC column and leaves a residue suitable for mass-spectral analysis. The interface includes a portable, stand-alone apparatus having a plural stage vacuum station, a continuous ribbon or belt, a drive train magnetically coupled to an external drive motor, a calibrated HPLC delivery system, a heated probe tip and means located adjacent the probe tip for direct ionization of the residue on the belt. The interface is also capable of being readily adapted to fit any mass spectrometer.

  20. Preparation of macroporous methacrylate-based monoliths for chromatographic applications by the Reactive Gelation Process.

    PubMed

    Bechtle, M; Butté, A; Storti, G; Morbidelli, M

    2010-07-09

    Polymeric monoliths are a relatively new separation medium for chromatographic applications. The innovative approach to produce such monoliths, the Reactive Gelation Process, presented by Marti et al. [1] for polystyrene macroporous materials is applied to a methacrylate-based material. It is shown that it is possible to create a macroporous structure by Reactive Gelation also with this polymer even if the properties of the material are different. Besides the analysis of the material by SEM and BET, several chromatographic methods are used to analyze the material properties. The ISEC experiments showed a much smaller size exclusion effect than in conventional packed beds. The permeability of the material is comparable to a packed bed with 4.13 μm particles. The column efficiency is not changing for increasing flow rates. Because of the high efficiency of the material, shorter columns are needed and therefore the comparatively low permeability is compensated. The monolith also exhibits a significant adsorption capacity for hydrophobic interaction, which makes it suitable for chromatographic purification processes.

  1. FTIR gas chromatographic analysis of perfumes

    NASA Astrophysics Data System (ADS)

    Diederich, H.; Stout, Phillip J.; Hill, Stephen L.; Krishnan, K.

    1992-03-01

    Perfumes, natural or synthetic, are complex mixtures consisting of numerous components. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) techniques have been extensively utilized for the analysis of perfumes and essential oils. A limited number of perfume samples have also been analyzed by FT-IR gas chromatographic (GC-FTIR) techniques. Most of the latter studies have been performed using the conventional light pipe (LP) based GC-FTIR systems. In recent years, cold-trapping (in a matrix or neat) GC-FTIR systems have become available. The cold-trapping systems are capable of sub-nanogram sensitivities. In this paper, comparison data between the LP and the neat cold-trapping GC- FTIR systems is presented. The neat cold-trapping interface is known as Tracer. The results of GC-FTIR analysis of some commercial perfumes is also presented. For comparison of LP and Tracer GC-FTIR systems, a reference (synthetic) mixture containing 16 major and numerous minor constituents was used. The components of the mixture are the compounds commonly encountered in commercial perfumes. The GC-FTIR spectra of the reference mixture was obtained under identical chromatographic conditions from an LP and a Tracer system. A comparison of the two sets of data thus generated do indeed show the enhanced sensitivity level of the Tracer system. The comparison also shows that some of the major components detected by the Tracer system were absent from the LP data. Closer examination reveals that these compounds undergo thermal decomposition on contact with the hot gold surface that is part of the LP system. GC-FTIR data were obtained for three commercial perfume samples. The major components of these samples could easily be identified by spectra search against a digitized spectral library created using the Tracer data from the reference mixture.

  2. Mental capacity.

    PubMed

    Williams, Ruth

    2010-02-03

    Three short videos exploring some of the different principles in the Mental Capacity Act 2009 are available on Social Care TV, an online channel intended mainly for the social care sector, although the films are relevant to any professionals whose work is affected by the act. The dramas, which are set in a residential home, a person's own home and a residential school for young people with learning difficulties, concern thedecision-making process and can be viewed at www.scie.org.uk/socialcaretv/topic.asp?guid=377dbe1b-de0c-4d66-bb87-22a243542db2.

  3. Qualitative evaluation of chromatographic data from quality control schemes using a support vector machine.

    PubMed

    Ventura, M; Sanchez-Niubo, A; Ruiz, F; Agell, N; Ventura, R; Angulo, C; Domingo-Salvany, A; Segura, J; Torre, R de la

    2008-01-01

    The qualitative evaluation of chromatographic data in the framework of external quality assurance schemes is considered in this paper. The homogeneity in the evaluation of chromatographic data among human experts in samples with analytes close to the limit of detection of analytical methods was examined and also a Support Vector Machine (SVM) was developed as an alternative to experts for a more homogeneous and automatic evaluation. A set of 105 ion chromatograms obtained by anti-doping control laboratories was used in this study. The quality of the ion chromatograms was evaluated qualitatively by nine independent experts (associating a score from 0 to 4) and also more objectively taking into account chromatographic parameters (peak width, asymmetry, resolution and S/N ratio). Results obtained showed a high degree of variability among experts when judging ion chromatograms. Experts applying extremely outlying evaluation criteria were identified and excluded from the data used to develop the SVM. This machine was built providing the system with qualitative information (scores assigned by experts) and with objective data (parameters) of the ion chromatograms. A seven-fold cross-validation approach was used to train and to evaluate the predictive ability of the machine. According to the results obtained, the SVM developed was found to be close to the reasoning process followed by the homogeneous human expert group. This machine also could provide a scoring system to sort laboratories according to the quality of their results. The qualitative evaluation of analytical records using a scoring system allowed the identification of the main factors affecting the quality of chromatographic analytical data, such as the specific analytical technique applied and the adherence to guidelines for reporting positive results.

  4. METHOD OF PEAK CURRENT MEASUREMENT

    DOEpatents

    Baker, G.E.

    1959-01-20

    The measurement and recording of peak electrical currents are described, and a method for utilizing the magnetic field of the current to erase a portion of an alternating constant frequency and amplitude signal from a magnetic mediums such as a magnetic tapes is presented. A portion of the flux from the current carrying conductor is concentrated into a magnetic path of defined area on the tape. After the current has been recorded, the tape is played back. The amplitude of the signal from the portion of the tape immediately adjacent the defined flux area and the amplitude of the signal from the portion of the tape within the area are compared with the amplitude of the signal from an unerased portion of the tape to determine the percentage of signal erasure, and thereby obtain the peak value of currents flowing in the conductor.

  5. SPANISH PEAKS PRIMITIVE AREA, MONTANA.

    USGS Publications Warehouse

    Calkins, James A.; Pattee, Eldon C.

    1984-01-01

    A mineral survey of the Spanish Peaks Primitive Area, Montana, disclosed a small low-grade deposit of demonstrated chromite and asbestos resources. The chances for discovery of additional chrome resources are uncertain and the area has little promise for the occurrence of other mineral or energy resources. A reevaluation, sampling at depth, and testing for possible extensions of the Table Mountain asbestos and chromium deposit should be undertaken in the light of recent interpretations regarding its geologic setting.

  6. Twin Peaks (B/W)

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The Twin Peaks are modest-size hills to the southwest of the Mars Pathfinder landing site. They were discovered on the first panoramas taken by the IMP camera on the 4th of July, 1997, and subsequently identified in Viking Orbiter images taken over 20 years ago. The peaks are approximately 30-35 meters (-100 feet) tall. North Twin is approximately 860 meters (2800 feet) from the lander, and South Twin is about a kilometer away (3300 feet). The scene includes bouldery ridges and swales or 'hummocks' of flood debris that range from a few tens of meters away from the lander to the distance of the South Twin Peak. The large rock at the right edge of the scene is nicknamed 'Hippo'. This rock is about a meter (3 feet) across and 25 meters (80 feet) distant.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology (Caltech). The IMP was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

  7. Fitting formula for the injection volume of a gas chromatograph for radio-xenon sampling in the lower troposphere.

    PubMed

    Shu-jiang, Liu; Zhan-ying, Chen; Shi-lian, Wang; Yin-zhong, Chang; Qi, Li; Yuan-qing, Fan; Yun-gang, Zhao; Huai-mao, Jia; Xin-jun, Zhang; Jun, Wang

    2014-06-01

    GC is usually used for xenon concentration and radon removal in the International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty. In a gas chromatograph, the injection volume is defined to calculate the column capacity. In this paper, the injection volume was investigated and a fitting formula for the injection volume was derived and discussed subsequently. As a consequence, the xenon injection volume exponentially decreased with the column temperature increased, but exponentially increased as the flow rate increased.

  8. A rapid high-performance liquid chromatographic method for the simultaneous quantitation of aspirin, salicylic acid, and caffeine in effervescent tablets.

    PubMed

    Sawyer, MaryJean; Kumar, Vimal

    2003-09-01

    A rapid reversed-phase high-performance liquid chromatographic procedure is developed and validated for the simultaneous quantitation of aspirin, salicylic acid, and caffeine extracted from an effervescent tablet. The method uses a Hypersil C18 column (5 micro m, 15 cm x 4.6 mm) for an isocratic elution in a water-methanol-acetic acid mobile phase at a wavelength of 275 nm. The tablets' buffering effects and acid neutralizing capacity require an extraction solvent of methanol-formic acid. The range of linearity for aspirin is 0.5-1.25 mg/mL, caffeine 0.065-0.195 mg/mL, and salicylic acid 0.4-6.0% of aspirin. The overall recovery is 100.2%, 100.7%, and 99.2% for aspirin, caffeine, and salicylic acid, respectively. Under the conditions of the method, aspirin, caffeine, and salicylic acid are adequately resolved with proper peak symmetry in less than 7 min.

  9. Correlation Between Local Structure and Boson Peak in Metallic Glasses

    NASA Astrophysics Data System (ADS)

    Ahmad, Azkar Saeed; Zhao, Xiangnan; Xu, Mingxiang; Zhang, Dongxian; Hu, Junwen; Fecht, Hans J.; Wang, Xiaodong; Cao, Qingping; Jiang, J. Z.

    2017-01-01

    We made a systematic study of the boson peak for six different Zr-based metallic glasses and found a universal correlation between average local atomic structure and boson peak. It is found that the boson peak can be decomposed into six characteristic vibratory modes, i.e., Debye's vibratory mode and five Einstein's vibratory modes. By using the Ioffe-Regel condition over all studied Zr-based metallic glasses, we reveal that atomic pair correlation function exactly maps on the low-temperature dynamics and the origin of the boson peak, which is the sum of vibrations of local density fluctuation domains in the glasses. In addition, it is found that the Debye's type oscillators are the major contributors to the low-temperature specific heat capacities. This study opens a new way of understanding the relationship of the physical properties with the atomic arrangements in glasses.

  10. Chromatographic and spectroscopic profiles of Cannabis of different origins: Part I.

    PubMed

    Brenneisen, R; elSohly, M A

    1988-11-01

    High-resolution capillary gas chromatography with flame ionization detection and mass spectrometry (GC and GC/MS) and high-performance liquid chromatography (HPLC) were used to establish complex chemical profiles (chemical signatures) of Cannabis samples of known origin. Over 100 compounds could be differentiated, including noncannabinoids (terpenes, alkanes) as well as minor and major cannabinoids and their acids. A characteristic peak pattern was found within a limited number of specimens of identical origin. Correlation studies on the basis of peak area ratios [A(x)/A(i.s.)] showed the feasibility of tracing Cannabis chemically to its country of origin. Several forensic science applications for the chromatographic and spectroscopic profiles of confiscated Cannabis samples are discussed, such as detection of additives (phencyclidine), differentiation of chemotypes, and monitoring of tetrahydrocannabinol (THC) potency.

  11. WHEELER PEAK ROADLESS AREA, NEVADA.

    USGS Publications Warehouse

    Whitebread, Donald H.; Kluender, Steven E.

    1984-01-01

    Field investigations to evaluate the mineral-resource potential of the Wheeler Peak Roadless Area in east-central Nevada were conducted. The field studies included geologic mapping, geochemical sampling, geophysical surveys, and a survey of mines and prospects. Several areas in the sedimentary and granitic rocks in the lower plate of the Snake Range decollement have probable mineral-resource potential for tungsten, beryllium, and lead. A small area of gravels near the north border of the area has a probable mineral-resource potential for placer gold. The geologic setting is not conducive for the occurrence of energy resources.

  12. GRANITE PEAK ROADLESS AREA, CALIFORNIA.

    USGS Publications Warehouse

    Huber, Donald F.; Thurber, Horace K.

    1984-01-01

    The Granite Peak Roadless Area occupies an area of about 5 sq mi in the southern part of the Trinity Alps of the Klamath Mountains, about 12 mi north-northeast of Weaverville, California. Rock and stream-sediment samples were analyzed. All streams draining the roadless area were sampled and representative samples of the rock types in the area were collected. Background values were established for each element and anomalous values were examined within their geologic settings and evaluated for their significance. On the basis of mineral surveys there seems little likelihood for the occurrence of mineral or energy resources.

  13. GLACIER PEAK ROADLESS AREA, WASHINGTON.

    USGS Publications Warehouse

    Church, S.E.; Johnson, F.L.

    1984-01-01

    A mineral survey outlined areas of mineral-resource potential in the Glacier Peak Roadless Area, Washington. Substantiated resource potential for base and precious metals has been identified in four mining districts included in whole or in part within the boundary of the roadless area. Several million tons of demonstrated base- and precious-metal resources occur in numerous mines in these districts. Probable resource potential for precious metals exists along a belt of fractured and locally mineralized rock extending northeast from Monte Cristo to the northeast edge of the roadless area.

  14. [Ion-exchange chromatographic behavior and characterization of Staphylococcus aureus in exponential phase].

    PubMed

    Chen, Zhaohua; Liu, Shutao; Xue, Weiming; Lai, Weiping; Rao, Pingfan

    2004-05-01

    A rapid, simple and sensitive method was developed to characterize S. aureus in exponential phase by a high performance ion-exchange chromatograph equipped with a laser light-scattering detector. An ion-exchange column (TSKgel SuperQ-TOYOPEARL 650C column, 7.6 mm i.d. x 100 mm, Tosoh, Japan) was used for the separation. The mobile phase was a 20 mmol/L piperazine-hydrochloric acid (pH 6.0) buffer. It was found that S. aureus in exponential phase exhibited two elution peaks. Transmission electron microscope (TEM) showed that the bacterial cells in the first peak appeared to be circular, while the cells in the second one appeared to be elliptical and had one obvious diaphragm. It is found that the proliferation capability of the second fraction was better than the first fraction by 65.3%. These results suggested that the first fraction was the S. aureus that stopped dividing, while the second one was the S. aureus that were undergoing cell division. Therefore, the chromatographic method developed here may be a promising tool for the rapid and efficient separation and characterization of bacterial cells.

  15. Batch-to-batch quality consistency evaluation of botanical drug products using multivariate statistical analysis of the chromatographic fingerprint.

    PubMed

    Xiong, Haoshu; Yu, Lawrence X; Qu, Haibin

    2013-06-01

    Botanical drug products have batch-to-batch quality variability due to botanical raw materials and the current manufacturing process. The rational evaluation and control of product quality consistency are essential to ensure the efficacy and safety. Chromatographic fingerprinting is an important and widely used tool to characterize the chemical composition of botanical drug products. Multivariate statistical analysis has showed its efficacy and applicability in the quality evaluation of many kinds of industrial products. In this paper, the combined use of multivariate statistical analysis and chromatographic fingerprinting is presented here to evaluate batch-to-batch quality consistency of botanical drug products. A typical botanical drug product in China, Shenmai injection, was selected as the example to demonstrate the feasibility of this approach. The high-performance liquid chromatographic fingerprint data of historical batches were collected from a traditional Chinese medicine manufacturing factory. Characteristic peaks were weighted by their variability among production batches. A principal component analysis model was established after outliers were modified or removed. Multivariate (Hotelling T(2) and DModX) control charts were finally successfully applied to evaluate the quality consistency. The results suggest useful applications for a combination of multivariate statistical analysis with chromatographic fingerprinting in batch-to-batch quality consistency evaluation for the manufacture of botanical drug products.

  16. Chromatographic Separations of Enantiomers and Underivatized Oligosaccharides

    SciTech Connect

    Liu, Ying

    2004-01-01

    My graduate research has focused on separation science and bioanalytical analysis, which emphasized in method development. It includes three major areas: enantiomeric separations using high performance liquid chromatography (HPLC), Super/subcritical fluid chromatography (SFC), and capillary electrophoresis (CE); drug-protein binding behavior studies using CE; and carbohydrate analysis using liquid chromatograph-electrospray ionization mass spectrometry (LC-ESI-MS). Enantiomeric separations continue to be extremely important in the pharmaceutical industry. An in-depth evaluation of the enantiomeric separation capabilities of macrocyclic glycopeptides CSPs with SFC mobile phases was investigated using a set of over 100 chiral compounds. It was found that the macrocyclic based CSPs were able to separate enantiomers of various compounds with different polarities and functionalities. Seventy percent of all separations were achieved in less than 4 min due to the high flow rate (4.0 ml/min) that can be used in SFC. Drug-protein binding is an important process in determining the activity and fate of a drug once it enters the body. Two drug/protein systems have been studied using frontal analysis CE method. More sensitive fluorescence detection was introduced in this assay, which overcame the problem of low sensitivity that is common when using UV detection for drug-protein studies. In addition, the first usage of an argon ion laser with 257 nm beam coupled with CCD camera as a frontal analysis detection method enabled the simultaneous observation of drug fluorescence as well as the protein fluorescence. LC-ESI-MS was used for the separation and characterization of underivatized oligosaccharide mixtures. With the limits of detection as low as 50 picograms, all individual components of oligosaccharide mixtures (up to 11 glucose-units long) were baseline resolved on a Cyclobond I 2000 column and detected using ESI-MS. This system is characterized by high chromatographic

  17. Peak Overpressures for Internal Blast

    DTIC Science & Technology

    1979-06-01

    61 70 115 132 CSHSN4 012 PETN , ,fltrythritltitraitr~l. 52 56 103 110 CaNS012 HNS , Hianitrobenrene 48 57 94 112 C6N~O Peftanitrobertuaqw 56 64 107...TEMPERATURE, K FIGURE 7. Heat Capacity Ratio k (CV + R)/C for Explosion Products. pentaerythritol tetranitrate ( PETN ), an explosive approxi- mately balanced in...overpressure range, the overpressures devel- oped by a given fuel-air ratio of PETN are less than those for TNT. The internal blast yield for PETN is

  18. Gas chromatographic determination of yohimbine in commercial yohimbe products.

    PubMed

    Betz, J M; White, K D; der Marderosian, A H

    1995-01-01

    The bark of Pausinystalia yohimbe [K. Schumann] Pierre (Rubiaceae), long valued as an aphrodisiac in West Africa, recently has been promoted in the United States as a dietary supplement alternative to anabolic steroids for enhancement of athletic performance. As the number of yohimbe products on the retail market increases, concerns about their safety are raised because of the reported toxicity of yohimbine (the major alkaloid of the plant). Although plant materials are usually identified microscopically, we were unable to identify them in many of the products, because as their labels indicated, the products were mixtures of various botanicals or were bark extracts and contained little or no plant material. A method for extraction and capillary gas chromatographic (GC) separation of the alkaloids of P. yohimbe was, therefore, developed and used to analyze a number of commercial yohimbe products. The method involved solvent extraction and partitioning in chloroform-water followed by separation on a methyl silicone capillary GC column (N-P detection). Comparisons of chromatograms of extracts of authentic bark with those of commercial products indicated that, although many products contained measurable quantities of the alkaloid yohimbine, they were largely devoid of the other alkaloids previously reported in this species. Concentrations of yohimbine in the commercial products ranged from < 0.1 to 489 ppm, compared with 7089 ppm in the authentic material. Authentic bark has been reported to contain up to 6% total alkaloids, 10-15% of which are yohimbine. The possible presence of undeclared diluents in the products was indicated by peaks in product chromatograms but not in those of authentic bark.

  19. Reduction in peak oxygen uptake after prolonged bed rest

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Kozlowski, S.

    1982-01-01

    The hypothesis that the magnitude of the reduction in peak oxygen uptake (VO2) after bed rest is directly proportional to the level of pre-bed rest peak VO2 is tested. Complete pre and post-bed rest working capacity and body weight data were obtained from studies involving 24 men (19-24 years old) and 8 women (23-34 years old) who underwent bed rest for 14-20 days with no remedial treatments. Results of regression analyses of the present change in post-bed rest peak VO2 on pre-bed rest peak VO2 with 32 subjects show correlation coefficients of -0.03 (NS) for data expressed in 1/min and -0.17 for data expressed in ml/min-kg. In addition, significant correlations are found that support the hypothesis only when peak VO2 data are analyzed separately from studies that utilized the cycle ergometer, particularly with subjects in the supine position, as opposed to data obtained from treadmill peak VO2 tests. It is concluded that orthostatic factors, associated with the upright body position and relatively high levels of physical fitness from endurance training, appear to increase the variability of pre and particularly post-bed rest peak VO2 data, which would lead to rejection of the hypothesis.

  20. Use of a modified Tenax GC column packing for the direct gas chromatographic analysis of phenols in water at the ppm level.

    PubMed

    Bartle, K D; Elstub, J; Novotny, M; Robinson, R J

    1977-05-21

    Dilute solutions of phenols in water at the ppm level may be analysed gas chromatographically by direct injection onto a column with a packing similar to that used in the Viking 1975 spacecraft: Tenax GC (2,6-diphenyl-p-phenylene oxide polymer) modified with polymetaphenyl ether liquid phase to eradicate irreversible adsorption. Symmetrical peaks were observed for injections of less than 1 ng of phenol and some of its alkylated derivatives. Chromatographic properties of modified Tenax GC columns are reported along with their application to the analysis of some industrial effluents with previous work-up.

  1. Storing hydroelectricity to meet peak-hour demand

    SciTech Connect

    Valenti, M.

    1992-04-01

    This paper reports on pumped storage plants which have become an effective way for some utility companies that derive power from hydroelectric facilities to economically store baseload energy during off-peak hours for use during peak hourly demands. According to the Electric Power Research Institute (EPRI) in Palo Alto, Calif., 36 of these plants provide approximately 20 gigawatts, or about 3 percent of U.S. generating capacity. During peak-demand periods, utilities are often stretched beyond their capacity to provide power and must therefore purchase it from neighboring utilities. Building new baseload power plants, typically nuclear or coal-fired facilities that run 24 hours per day seven days a week, is expensive, about $1500 per kilowatt, according to Robert Schainker, program manager for energy storage at the EPRI. Schainker the that building peaking plants at $400 per kilowatt, which run a few hours a day on gas or oil fuel, is less costly than building baseload plants. Operating them, however, is more expensive because peaking plants are less efficient that baseload plants.

  2. Chromatographic Separation of Vitamin E Enantiomers.

    PubMed

    Fu, Ju-Yen; Htar, Thet-Thet; De Silva, Leanne; Tan, Doryn Meam-Yee; Chuah, Lay-Hong

    2017-02-04

    Vitamin E is recognized as an essential vitamin since its discovery in 1922. Most vegetable oils contain a mixture of tocopherols and tocotrienols in the vitamin E composition. Structurally, tocopherols and tocotrienols share a similar chromanol ring and a side chain at the C-2 position. Owing to the three chiral centers in tocopherols, they can appear as eight different stereoisomers. Plant sources of tocopherol are naturally occurring in the form of RRR while synthetic tocopherols are usually in the form of all-racemic mixture. Similarly, with only one chiral center, natural tocotrienols occur as the R-isoform. In this review, we aim to discuss a few chromatographic methods that had been used to separate the stereoisomers of tocopherols and tocotrienols. These methods include high performance liquid chromatography, gas chromatography and combination of both. The review will focus on method development including selection of chiral columns, detection method and choice of elution solvent in the context of separation efficiency, resolution and chiral purity. The applications for separation of enantiomers in vitamin E will also be discussed especially in terms of the distinctive biological potency among the stereoisoforms.

  3. Chromatographic and mass spectrometric techniques in studies on oxidative stress in autism.

    PubMed

    Kałużna-Czaplińska, Joanna; Jóźwik-Pruska, Jagoda

    2016-04-15

    Healthy body is characterized by the presence of a dynamic and balanced equilibrium between the production of reactive oxygen species (ROS) and the antioxidant capacity. In oxidative stress this balance is switched to reactions of oxidation leading to increased production of ROS, exceeding the capacity of physiological antioxidant systems. Oxidative stress is known to be linked to many disturbances, disorders and diseases. One of these is the autism spectrum disorder (ASD). ASD is a neurodevelopmental disorder manifested by abnormalities in social communication and interaction, as well as by occurrence of repetitive, restricted patterns of behavior or activities. It is believed that adequate knowledge about the oxidative stress biomarkers and the possibility of their reliable measuring could be useful in broadening knowledge on various diseases including ASD. A high number of compounds have been proposed as biomarkers of oxidative stress. Some of these are connected with the severity of ASD. The present review gives a summary of the chromatographic techniques used for the determination of biomarkers for oxidative stress in autism, and of other compounds important in this context. The first part of the review focuses on the correlation between oxidative stress and autism. The second part describes applications of chromatographic and mass spectrometric methods to the analysis of different metabolites connected with oxidative stress in biological fluids of autistic children. Advantages as well as disadvantages of the application of these methods for the analysis of different types of oxidative stress biomarkers are discussed.

  4. Liquid chromatographic separation of antidepressant drugs: I. Tricyclics.

    PubMed

    Beierle, F A; Hubbard, R W

    1983-01-01

    A simple normal-phase (silica), high-performance liquid chromatographic (HPLC) assay of amitriptyline (AMI), doxepin (DOX), imipramine (IMI), nortriptyline (NORT), desmethyldoxepin (DESDOX), desipramine (DESIP), and protriptyline (PRO) in serum with no coelution is described here. Trimipramine and promazine were used as internal standards. Extraction of the 1.0-ml serum samples (collected in plastic) was done with Bond-Elut C18 columns. The compounds of interest were eluted with 10 mM methanolic ammonium acetate. The eluates were evaporated at 56-58 degrees C and reconstituted with 200 microliters of the mobile phase. The mobile phase was absolute ethanol-acetonitrile-tert-butylamine (98:2:0.05, vol/vol/vol). Detection of eluted drugs was at 254 nm at 0.01 absorbance units full scale (AUFS), except for PRO, which was detected at 229 nm at 0.02 AUFS. Absolute recoveries were 87-97%. A 5-micron silica (4.6 X 250 mm) HPLC column was used; results with a 10-micron silica column (3.9 X 300 mm) are also presented. Peak height ratios with trimipramine were linear for each analyte between 25 and 1200 ng/ml. Peak height ratios with promazine as the internal standard were linear for each analyte between 25 and 600 ng/ml. Detection limits under the conditions described were 2 ng/ml for AMI, DOX, and IMI, 4 ng/ml for NORT, DESDOX, and DESIP, and 10 ng/ml for PRO. Coefficients of within-day and day-to-day variation at three concentration levels were less than 9.8% and less than 11.2%, respectively. The hydroxylated metabolites of IMI, DES, NORT, and the cis isomer of DOX are discussed. Steady-state daily dosages and corresponding serum levels are presented for 69 patients. The total assay time was less than 10 min for DESIP and 12 min for PRO. This assay can be used in correlating serum levels with clinical effects, compliancy, and pharmacokinetic studies.

  5. BARCHAN: Blob Alignment for Robust CHromatographic ANalysis.

    PubMed

    Couprie, Camille; Duval, Laurent; Moreaud, Maxime; Hénon, Sophie; Tebib, Mélinda; Souchon, Vincent

    2017-02-10

    Two-dimensional gas chromatography (GC×GC) plays a central role into the elucidation of complex samples. The automation of the identification of peak areas is of prime interest to obtain a fast and repeatable analysis of chromatograms. To determine the concentration of compounds or pseudo-compounds, templates of blobs are defined and superimposed on a reference chromatogram. The templates then need to be modified when different chromatograms are recorded. In this study, we present a chromatogram and template alignment method based on peak registration called BARCHAN. Peaks are identified using a robust mathematical morphology tool. The alignment is performed by a probabilistic estimation of a rigid transformation along the first dimension, and a non-rigid transformation in the second dimension, taking into account noise, outliers and missing peaks in a fully automated way. Resulting aligned chromatograms and masks are presented on two datasets. The proposed algorithm proves to be fast and reliable. It significantly reduces the time to results for GC×GC analysis.

  6. Ion chromatographic separation of inorganic ions using a combination of hydrophilic interaction chromatographic column and cation-exchange resin column.

    PubMed

    Arai, Kaori; Mori, Masanobu; Hironaga, Takahiro; Itabashi, Hideyuki; Tanaka, Kazuhiko

    2012-04-01

    A combination of hydrophilic interaction chromatographic (HILIC) column and a weakly acidic cation-exchange resin (WCX) column was used for simultaneous separation of inorganic anions and cations by ion chromatography (IC). Firstly, the capability of HILIC column for the separation of analyte ions was evaluated under acidic eluent conditions. The columns used were SeQuant ZIC-HILIC (ZIC-HILIC) with a sulfobetaine-zwitterion stationary phase (ZIC-HILIC) and Acclaim HILIC-10 with a diol stationary phase (HILIC-10). When using tartaric acid as the eluent, the HILIC columns indicated strong retentions for anions, based on ion-pair interaction. Especially, HILIC-10 could strongly retain anions compared with ZIC-HILIC. The selectivity for analyte anions of HILIC-10 with 5 mmol/L tartaric acid eluent was in the order of I(-) > NO3(-) > Br(-) > Cl(-) > H2PO4(-). However, since HILIC-10 could not separate analyte cations, a WCX column (TSKgel Super IC-A/C) was connected after the HILIC column in series. The combination column system of HILIC and WCX columns could successfully separate ten ions (Na+, NH4+, K+, Mg2+, Ca2+, H2PO4(-), Cl(-), Br(-), NO3(-) and I(-)) with elution of 4 mmol/L tartaric acid plus 8 mmol/L 18-crown-6. The relative standard deviations (RSDs) of analyte ions by the system were in the ranges of 0.02% - 0.05% in retention times and 0.18% - 5.3% in peak areas through three-time successive injections. The limits of detection at signal-to-noise ratio of 3 were 0.24 - 0.30 micromol/L for the cations and 0.31 - 1.2 micromol/L for the anions. This system was applied for the simultaneous determination of the cations and the anions in a vegetable juice sample with satisfactory results.

  7. CHROMATOGRAPHIC AND MASS SPECTRAL STUDIES OF PERFLUOROOCTANESULFONATE AND THREE PERFLUOROOCTANESULFONAMIDES

    EPA Science Inventory

    The chromatographic and mass spectral characteristics of perfluorooctanesulfonate (PFOS) and three nitrogen-substituted perfluorooctanesulfonamides have been obtained. A methyl/phenol mixed phase fused silica capillary column was used for GC analysis, while a C18 reversed phase ...

  8. Moving from fast to ballistic gradient in liquid chromatography/tandem mass spectrometry pharmaceutical bioanalysis: Matrix effect and chromatographic evaluations.

    PubMed

    De Nardi, Claudio; Bonelli, Fabio

    2006-01-01

    The paper describes the steps taken by the authors to move from a fast to a ballistic gradient in routine liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis of plasma samples from pharmacokinetic (PK) profiling of new chemical entities. The reduction of column dimensions from 50 x 4.6 mm to 30 x 2.1 mm followed by optimization of chromatographic separation led to a decrease in the typical runtime from 5 (fast) to 2 min (ballistic) using an API4000 tandem mass spectrometer in Turbo Ionspray mode for detection. Three analytical standards representing typical molecular structures from our sample repository were used to spike plasma from four different species (rat, dog, human and mouse). Two different approaches were used to evaluate matrix effect: post-column infusion and comparison of the peak areas of neat standards and standards spiked after extraction into different pools of plasma; the influence of PEG400 as a typical dosing vehicle was also considered. Two different protein precipitation procedures were taken into account for sample extraction prior to injection. Peak shape, width and height, selectivity and sensitivity of the method were taken into account for chromatographic evaluation. The ballistic method was successfully cross-validated with the conventional fast gradient chromatographic assay.

  9. Gas chromatographic separation of hydrogen isotopes using metal hydrides

    SciTech Connect

    Aldridge, F.T.

    1984-05-09

    A study was made of the properties of metal hydrides which may be suitable for use in chromatographic separation of hydrogen isotopes. Sixty-five alloys were measured, with the best having a hydrogen-deuterium separation factor of 1.35 at 60/sup 0/C. Chromatographic columns using these alloys produced deuterium enrichments of up to 3.6 in a single pass, using natural abundance hydrogen as starting material. 25 references, 16 figures, 4 tables.

  10. Method for liquid chromatographic extraction of strontium from acid solutions

    DOEpatents

    Horwitz, E. Philip; Dietz, Mark L.

    1992-01-01

    A method and apparatus for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column is described. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water.

  11. Mortality and morbidity peaks modeling: An extreme value theory approach.

    PubMed

    Chiu, Y; Chebana, F; Abdous, B; Bélanger, D; Gosselin, P

    2016-09-01

    Hospitalizations and deaths belong to the most studied health variables in public health. Those variables are usually analyzed through mean events and trends, based on the whole dataset. However, this approach is not appropriate to comprehend health outcome peaks which are unusual events that strongly impact the health care network (e.g. overflow in hospital emergency rooms). Peaks can also be of interest in etiological research, for instance when analyzing relationships with extreme exposures (meteorological conditions, air pollution, social stress, etc.). Therefore, this paper aims at modeling health variables exclusively through the peaks, which is rarely done except over short periods. Establishing a rigorous and general methodology to identify peaks is another goal of this study. To this end, the extreme value theory appears adequate with statistical tools for selecting and modeling peaks. Selection and analysis for deaths and hospitalizations peaks using extreme value theory have not been applied in public health yet. Therefore, this study also has an exploratory goal. A declustering procedure is applied to the raw data in order to meet extreme value theory requirements. The application is done on hospitalization and death peaks for cardiovascular diseases, in the Montreal and Quebec metropolitan communities (Canada) for the period 1981-2011. The peak return levels are obtained from the modeling and can be useful in hospital management or planning future capacity needs for health care facilities, for example. This paper focuses on one class of diseases in two cities, but the methodology can be applied to any other health peaks series anywhere, as it is data driven.

  12. Quantifying process tradeoffs in the operation of chromatographic sequences.

    PubMed

    Ngiam, Sheau-Huey; Bracewell, Daniel G; Zhou, Yuhong; Titchener-Hooker, Nigel J

    2003-01-01

    A method for the rapid representation of key process tradeoffs that need to be made during the analysis of chromatographic sequences has been proposed. It involves the construction of fractionation and maximum purification factor versus yield diagrams, which can be completed easily on the basis of chromatographic data. The output of the framework developed reflects the degree of tradeoff between levels of yield and purity and provides a fast and precise prediction of the sample fraction collection strategy needed to meet a desired process specification. The usefulness of this approach for the purposes of product purification and contaminant removal in a single chromatographic step has been successfully demonstrated in an earlier paper and it is now extended by application to a chromatographic sequence: the separation of a hypothetical three-component protein system by hydrophobic interaction chromatography (HIC) followed by size exclusion chromatography (SEC). The HIC operation has a strong impact upon the subsequent SEC step. The studies show how the analysis of performance in such a chromatographic sequence can be carried out easily and in a straightforward fashion using the fractionation diagram approach. The methodology proposed serves as a useful tool for identifying the process tradeoffs that must be made during operation of a sequence of chromatographic steps and indicates the impact on further processing of the cut-point decisions that are made.

  13. Peak clustering in two-dimensional gas chromatography with mass spectrometric detection based on theoretical calculation of two-dimensional peak shapes: the 2DAid approach.

    PubMed

    van Stee, Leo L P; Brinkman, Udo A Th

    2011-10-28

    A method is presented to facilitate the non-target analysis of data obtained in temperature-programmed comprehensive two-dimensional (2D) gas chromatography coupled to time-of-flight mass spectrometry (GC×GC-ToF-MS). One main difficulty of GC×GC data analysis is that each peak is usually modulated several times and therefore appears as a series of peaks (or peaklets) in the one-dimensionally recorded data. The proposed method, 2DAid, uses basic chromatographic laws to calculate the theoretical shape of a 2D peak (a cluster of peaklets originating from the same analyte) in order to define the area in which the peaklets of each individual compound can be expected to show up. Based on analyte-identity information obtained by means of mass spectral library searching, the individual peaklets are then combined into a single 2D peak. The method is applied, amongst others, to a complex mixture containing 362 analytes. It is demonstrated that the 2D peak shapes can be accurately predicted and that clustering and further processing can reduce the final peak list to a manageable size.

  14. Molten salt thermal energy storage for utility peaking loads

    NASA Technical Reports Server (NTRS)

    Ferrara, A.; Haslett, R.; Joyce, J.

    1977-01-01

    This paper considers the use of thermal energy storage (TES) in molten salts to increase the capacity of power plants. Five existing fossil and nuclear electric utility plants were selected as representative of current technology. A review of system load diagrams indicated that TES to meet loads over 95% of peak was a reasonable goal. Alternate TES heat exchanger locations were evaluated, showing that the stored energy should be used either for feedwater heating or to generate steam for an auxiliary power cycle. Specific salts for each concept are recommended. Design layouts were prepared for one plant, and it was shown that a TES tube/shell heat exchanger system could provide about 7% peaking capability at lower cost than adding steam generation capacity. Promising alternate heat exchanger concepts were also identified.

  15. Model for spectral and chromatographic data

    DOEpatents

    Jarman, Kristin [Richland, WA; Willse, Alan [Richland, WA; Wahl, Karen [Richland, WA; Wahl, Jon [Richland, WA

    2002-11-26

    A method and apparatus using a spectral analysis technique are disclosed. In one form of the invention, probabilities are selected to characterize the presence (and in another form, also a quantification of a characteristic) of peaks in an indexed data set for samples that match a reference species, and other probabilities are selected for samples that do not match the reference species. An indexed data set is acquired for a sample, and a determination is made according to techniques exemplified herein as to whether the sample matches or does not match the reference species. When quantification of peak characteristics is undertaken, the model is appropriately expanded, and the analysis accounts for the characteristic model and data. Further techniques are provided to apply the methods and apparatuses to process control, cluster analysis, hypothesis testing, analysis of variance, and other procedures involving multiple comparisons of indexed data.

  16. Cornflower (Centaurea cyanus L.) honey quality parameters: chromatographic fingerprints, chemical biomarkers, antioxidant capacity and others.

    PubMed

    Kuś, Piotr Marek; Jerković, Igor; Tuberoso, Carlo Ignazio Giovanni; Marijanović, Zvonimir; Congiu, Francesca

    2014-01-01

    The samples of cornflower (Centaurea cyanus L.) honey from Poland were subjected to ultrasonic solvent extraction applying the mixture of pentane and diethyl ether 1:2v/v (solvent A) as well as dichloromethane (solvent B). The major compounds of the extracts (analysed by GC-MS/GC-FID) were C13 and C9 norisoprenoids. Among them, (E)-3-oxo-retro-α-ionol (2.4-23.9% (solvent A); 3.9-14.4% (solvent B)) and (Z)-3-oxo-retro-α-ionol (3.7-29.9% (solvent A); 8.4-20.4% (solvent B)) were found to be useful as chemical biomarkers of this honey. Other abundant compounds were: methyl syringate (0.0-31.4% (solvent A); 0.0-25.4% (solvent B)) and 3-hydroxy-4-phenylbutan-2-one (1.6-15.8% (solvent A); 5.1-15.1% (solvent B)). HPLC-DAD analysis of the samples revealed lumichrome (4.7-10.0mg/kg), riboflavin (1.9-2.7mg/kg) and phenyllactic acid (112.1-250.5mg/kg) as typical compounds for this honey type. Antioxidant and antiradical properties as well as total phenolic content of the samples were found to be rather moderate by FRAP (ferric reducing antioxidant power), DPPH (1,1-diphenyl-2-picrylhydrazyl radical) and Folin-Ciocalteu assays, respectively. Additionally, CIE L(∗)a(∗)b(∗)C(∗)h chromatic coordinates were evaluated. Colour attributes of cornflower honey were characterised by elevated values of L(∗) and particularly high values of b(∗) and h coordinates, which correspond to medium bright honey with intense yellow colour.

  17. Separation and identification of various vulcanization agents and antioxidants in two types of rubber by chromatographic and spectrometric methods.

    PubMed

    Chauveau, S; Hamon, M; Leleu, E

    1991-11-01

    The aim of this study was to separate and identify by chromatographic and spectrometric methods, the various allergenic vulcanization agents and antioxidants used in the manufacture of industrial rubber. Specimens of elastomers were manufactured specially for this study. The specificity of the gas chromatographic method developed allows separation of all the manufacturing additives in the selected rubber types after one injection only, even though they belong to extremely varied chemical categories. The GLC method was coupled with mass spectrometry, which permitted identification of the peaks obtained and the study of the fragmentation of the 4 reference products under various conditions. Separation by TLC was performed in parallel on the same extracts, allowing rapid identification of the products tested for, and showed new spots after vulcanization.

  18. Peak load management: Potential options

    SciTech Connect

    Englin, J.E.; De Steese, J.G.; Schultz, R.W.; Kellogg, M.A.

    1989-10-01

    This report reviews options that may be alternatives to transmission construction (ATT) applicable both generally and at specific locations in the service area of the Bonneville Power Administration (BPA). Some of these options have potential as specific alternatives to the Shelton-Fairmount 230-kV Reinforcement Project, which is the focus of this study. A listing of 31 peak load management (PLM) options is included. Estimated costs and normalized hourly load shapes, corresponding to the respective base load and controlled load cases, are considered for 15 of the above options. A summary page is presented for each of these options, grouped with respect to its applicability in the residential, commercial, industrial, and agricultural sectors. The report contains comments on PLM measures for which load shape management characteristics are not yet available. These comments address the potential relevance of the options and the possible difficulty that may be encountered in characterizing their value should be of interest in this investigation. The report also identifies options that could improve the efficiency of the three customer utility distribution systems supplied by the Shelton-Fairmount Reinforcement Project. Potential cogeneration options in the Olympic Peninsula are also discussed. These discussions focus on the options that appear to be most promising on the Olympic Peninsula. Finally, a short list of options is recommended for investigation in the next phase of this study. 9 refs., 24 tabs.

  19. Development and validation of a high performance chromatographic method for determining sumatriptan in niosomes.

    PubMed

    Cózar-Bernal, M J; Rabasco, A M; González-Rodríguez, M L

    2013-01-01

    In this paper, a novel, precise, specific, accurate and rapid reversed-phase high performance liquid chromatographic method was developed, optimized and validated for determining sumatriptan succinate in niosomes with the best chromatographic peak resolution, reduced run time and low cost of analysis. The formulation has been previously optimized in terms of composition and preparation technique to obtain a high drug encapsulation efficiency and adequate vesicle size distribution. This method showed the best resolution by using Spherisorb OSD2 C18 column (250 mm × 4.6 mm, 5 μm) using phosphate buffer (0.05 M):acetonitrile (80:20, v/v; pH adjusted to 6.0) as a mobile phase at a flow rate of 1 mL/min and wavelength of 214 nm. The main objective of this research was to demonstrate the robustness of the reversed-phase HPLC method development by applying the Taguchi robust methodology. The signal-to-noise ratio (S/N) was employed as a quality measurement. This tool permits to establish the influence of some selected factors (acetonitrile:phosphate ratio, pH buffer, oven temperature and flow rate) on two responses (peak areas and retention time). On the basis of the results obtained, we can conclude that this analytical method was robust for all the factors studies, as exception of the flow rate, where the higher quality was obtained for the fewer values (0.8 mL/min). Therefore, this parameter must be carefully controlled when this method was employed, to avoid any modification in the peak areas overall.

  20. Effect of axial temperature gradient on chromatographic efficiency under adiabatic conditions.

    PubMed

    Horváth, Krisztián; Horváth, Szabolcs; Lukács, Diána

    2017-02-03

    The effect of axial temperature gradient on the chromatographic efficiency was studied under adiabatic conditions by a modeling approach. The equilibrium-dispersive model of chromatography was used for the calculations. The model was extended by taking into account the axial temperature gradient. The results show that due to the temperature gradient, there are retention and migration velocity gradients in the column. Since the retention factor, k, is not constant in the column, k cannot be calculated as the ratio of net retention and hold-up times. As a result of the gradual increase of migration velocity, the retention times of solutes decrease as the slope of temperature gradient increases. In addition, the band in the column have extra broadening due to larger migration velocity of the front of band. The width of bands becomes larger at larger change of temperature. In the same time, however, the release velocity of the compounds from the column is increasing as ΔT increases. Accordingly, an apparent peak compression effect makes the peaks thinner. As a result of the two counteracting effects (peak expansion, apparent peak compression) the column efficiency does not change significantly in case of axial temperature gradient under adiabatic conditions. The resolutions, however, decrease slightly due to the decrease of retention times.

  1. [Pyrolysis-gas chromatographic fingerprints with hierarchical cluster analysis for Dendrobium candidum Wall. ex Lindl].

    PubMed

    Wang, Lili; Wang, Cong; Pan, Zaifa; Sun, Fa

    2008-09-01

    The pyrogram fingerprints of Dendrobium candidum Wall. ex Lindl. from different regions were studied by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and compared with hierarchical cluster analysis. The effect of pyrolysis temperature on the fingerprint was examined by evolved gas analysis, and then 450 degrees C was selected as the optimized pyrolysis temperature. An amount of 0.4 mg of raw drug powder was pyrolysed in a vertical microfurnace pyrolyzer, and the products were directly introduced into a gas chromatograph equipped with a flame ionization detector (FID) and a fused-silica capillary column (30 m x 0.25 mm x 0.25 microm). The pyrogram fingerprints of 10 samples from different regions showed a high similarity and a good reproducibility with the relative standard deviations (RSDs) of the retention times less than 0.33% and the RSDs of the relative peak areas less than 4.8%. Therefore, each sample was characterized by the peak area of 31 peaks in each pyrogram and these peaks were employed for hierarchical cluster analysis. Furthermore, the discrimination of the sample from different regions was achieved by hierarchical cluster analysis via recognizing the 10 x 31 data matrix. Thus, the results proved it is a simple, rapid and accurate method suitable for the quality control of the traditional Chinese medicines.

  2. Measuring peak expiratory flow in general practice: comparison of mini Wright peak flow meter and turbine spirometer.

    PubMed Central

    Jones, K P; Mullee, M A

    1990-01-01

    OBJECTIVE--To compare measurements of the peak expiratory flow rate taken by the mini Wright peak flow meter and the turbine spirometer. DESIGN--Pragmatic study with randomised order of use of recording instruments. Phase 1 compared a peak expiratory flow type expiration recorded by the mini Wright peak flow meter with an expiration to forced vital capacity recorded by the turbine spirometer. Phase 2 compared peak expiratory flow type expirations recorded by both meters. Reproducibility was assessed separately. SETTING--Routine surgeries at Aldermoor Health Centre, Southampton. SUBJECTS--212 Patients aged 4 to 78 presenting with asthma or obstructive airways disease. Each patient contributed only once to each phase (105 in phase 1, 107 in phase 2), but some entered both phases on separate occasions. Reproducibility was tested on a further 31 patients. MAIN OUTCOME MEASURE--95% Limits of agreement between measurements on the two meters. RESULTS--208 (98%) Of the readings taken by the mini Wright meter were higher than the corresponding readings taken by the turbine spirometer, but the 95% limits of agreement (mean difference (2 SD] were wide (1 to 173 l/min). Differences due to errors in reproducibility were not sufficient to predict this level of disagreement. Analysis by age, sex, order of use, and the type of expiration did not detect any significant differences. CONCLUSIONS--The two methods of measuring peak expiratory flow rate were not comparable. The mini Wright meter is likely to remain the preferred instrument in general practice. PMID:2142611

  3. [Contamination mechanism and regeneration strategies of chromatographic resin in separation process for expression product from mammary gland bioreactor].

    PubMed

    Sun, Xiyan; Zhang, Yan; Li, Yan; Luo, Jian; Qin, Peiyong; Su, Zhiguo

    2011-11-01

    This study focused on the contamination mechanism and regeneration strategies of sulfopropyl ion exchange resin (SP Sepharose FF) during the separation of recombinant human lactoferrin from transgenic bovine milk. We analyzed primary constituents' contents in chromatorgraphic material and fractions. The results showed that the lipid in milk can clog the column or adhere to the resin through hydrophobic interaction, leading to an increase in column pressure. Some casein molecules were found to adsorb onto the resin through electrostatic interaction, therefore the adsorption capacity was decreased. There was no direct interaction between lactose and the resin in the chromatorgraphic process. Increased continuous chromatographic cycles and prolonged time interval between protein purification and column regeneration could enhance the undesirable interaction between the contaminants and resin, thus lowering the regeneration efficiency. NaOH was found to be effective in the removal of lipid and casein molecules from the column. Furthermore, normal microstructure and chromatographic performance of the ion exchanger was recovered after this cleaning procedure.

  4. QbD-oriented development and validation of a bioanalytical method for nevirapine with enhanced liquid-liquid extraction and chromatographic separation.

    PubMed

    Beg, Sarwar; Chaudhary, Vandna; Sharma, Gajanand; Garg, Babita; Panda, Sagar Suman; Singh, Bhupinder

    2016-06-01

    The present studies describe the systematic quality by design (QbD)-oriented development and validation of a simple, rapid, sensitive and cost-effective reversed-phase HPLC bioanalytical method for nevirapine in rat plasma. Chromatographic separation was carried out on a C18 column using isocratic 68:9:23% v/v elution of methanol, acetonitrile and water (pH 3, adjusted by orthophosphoric acid) at a flow rate of 1.0 mL/min using UV detection at 230 nm. A Box-Behnken design was applied for chromatographic method optimization taking mobile phase ratio, pH and flow rate as the critical method parameters (CMPs) from screening studies. Peak area, retention time, theoretical plates and peak tailing were measured as the critical analytical attributes (CAAs). Further, the bioanalytical liquid-liquid extraction process was optimized using an optimal design by selecting extraction time, centrifugation speed and temperature as the CMPs for percentage recovery of nevirapine as the CAA. The search for an optimum chromatographic solution was conducted through numerical desirability function. Validation studies performed as per the US Food and Drug Administration requirements revealed results within the acceptance limit. In a nutshell, the studies successfully demonstrate the utility of analytical QbD approach for the rational development of a bioanalytical method with enhanced chromatographic separation and recovery of nevirapine in rat plasma. Copyright © 2015 John Wiley & Sons, Ltd.

  5. Method and apparatus for chromatographic quantitative analysis

    DOEpatents

    Fritz, James S.; Gjerde, Douglas T.; Schmuckler, Gabriella

    1981-06-09

    An improved apparatus and method for the quantitative analysis of a solution containing a plurality of anion species by ion exchange chromatography which utilizes a single eluent and a single ion exchange bed which does not require periodic regeneration. The solution containing the anions is added to an anion exchange resin bed which is a low capacity macroreticular polystyrene-divinylbenzene resin containing quarternary ammonium functional groups, and is eluted therefrom with a dilute solution of a low electrical conductance organic acid salt. As each anion species is eluted from the bed, it is quantitatively sensed by conventional detection means such as a conductivity cell.

  6. Studies on chromatographic fingerprint and fingerprinting profile-efficacy relationship of polygoni perfoliati herba.

    PubMed

    Tian, Li; Zhao, Yang; Zhou, Xin; Chen, Hua-Guo; Zhao, Chao; Gong, Xiao-Jian

    2013-01-01

    Polygoni Perfoliati Herba is widely used in China with antibacterium, anti-inflammatory, expectorant, antitumor, and antivirus activities. To reveal the mechanisms of the activities of Polygoni Perfoliati Herba, the relationship between the fingerprinting profile and its bioactivities was investigated. In the present study, high-performance liquid chromatographic (HPLC) fingerprinting method was developed. The established method was applied to analyze 51 batches of Polygoni Perfoliati Herba samples collected from different locations or in different harvesting times in China. Chemometrics, including similarity analysis, hierarchical clustering analysis, and principal component analysis, were used to express their similarities. It was found that similarity values of the samples were in the range of 0.432-0.998. The results of analgesic tests indicated that Polygoni Perfoliati Herba could significantly inhibit pain induced by hot plate and acetic acid in mice. The results of anti-inflammatory tests showed that Polygoni Perfoliati Herba had good anti-inflammatory effects (P < 0.01) in two models including dimethyl benzene-induced ear edema and acetic acid-induced peritoneal permeability in mice. Combining the results from chromatographic fingerprints with those from bioactivities, we found that seven peaks from Polygoni Perfoliati Herba were mainly responsible for analgesic and anti-inflammatory activities.

  7. Remotely detected NMR for the characterization of flow and fast chromatographic separations using organic polymer monoliths.

    PubMed

    Teisseyre, Thomas Z; Urban, Jiri; Halpern-Manners, Nicholas W; Chambers, Stuart D; Bajaj, Vikram S; Svec, Frantisek; Pines, Alexander

    2011-08-01

    An application of remotely detected magnetic resonance imaging is demonstrated for the characterization of flow and the detection of fast, small molecule separations within hypercrosslinked polymer monoliths. The hyper-cross-linked monoliths exhibited excellent ruggedness, with a transit time relative standard deviation of less than 2.1%, even after more than 300 column volumes were pumped through at high pressure and flow. Magnetic resonance imaging enabled high-resolution intensity and velocity-encoded images of mobile phase flow through the monolith. The images confirm that the presence of a polymer monolith within the capillary disrupts the parabolic laminar flow profile that is characteristic of mobile phase flow within an open tube. As a result, the mobile phase and analytes are equally distributed in the radial direction throughout the monolith. Also, in-line monitoring of chromatographic separations of small molecules at high flow rates is shown. The coupling of monolithic chromatography columns and NMR provides both real-time peak detection and chemical shift information for small aromatic molecules. These experiments demonstrate the unique power of magnetic resonance, both direct and remote, in studying chromatographic processes.

  8. Headspace gas chromatographic method for determination of methyl bromide in food ingredients

    SciTech Connect

    DeVries, J.W.; Broge, J.M.; Schroeder, J.P.; Bowers, R.H.; Larson, P.A.; Burns, N.M.

    1985-11-01

    A headspace gas chromatographic (GC) method, which can be automated, has been developed for determination of methyl bromide. This method has been applied to wheat, flour, cocoa, and peanuts. Samples to be analyzed are placed in headspace sample vials, water is added, and the vials are sealed with Teflon-lined septa. After an appropriate equilibration time at 32 degrees C, the samples are analyzed within 10 h. A sample of the headspace is withdrawn and analyzed on a gas chromatograph equipped with an electron capture detector (ECD). Methyl bromide levels were quantitated by comparison of peak area with a standard. The standard was generated by adding a known amount of methyl bromide to a portion of the matrix being analyzed and which was known to be methyl bromide free. The detection limit of the method was 0.4 ppb. The coefficient of variation (CV) was 6.5% for wheat, 8.3% for flour, 3.3% for cocoa, and 11.6% for peanuts.

  9. The Phenomenology of Aesthetic Peak Experiences.

    ERIC Educational Resources Information Center

    Panzarella, Robert

    1980-01-01

    Descriptions of music and visual art peak experiences obtained from persons were content analyzed and factor analyzed. The peak experience accounts for mirrored conflicts in aesthetic norms and suggests a greater role for individual differences in aesthetic theories. (Author)

  10. 27 CFR 9.140 - Atlas Peak.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...). (c) Boundaries. The Atlas Peak viticultural area is located in Napa County, California. It lies entirely within the Napa Valley viticultural area. The beginning point is Haystack (peak) found in...

  11. Peak-flow characteristics of Virginia streams

    USGS Publications Warehouse

    Austin, Samuel H.; Krstolic, Jennifer L.; Wiegand, Ute

    2011-01-01

    Peak-flow annual exceedance probabilities, also called probability-percent chance flow estimates, and regional regression equations are provided describing the peak-flow characteristics of Virginia streams. Statistical methods are used to evaluate peak-flow data. Analysis of Virginia peak-flow data collected from 1895 through 2007 is summarized. Methods are provided for estimating unregulated peak flow of gaged and ungaged streams. Station peak-flow characteristics identified by fitting the logarithms of annual peak flows to a Log Pearson Type III frequency distribution yield annual exceedance probabilities of 0.5, 0.4292, 0.2, 0.1, 0.04, 0.02, 0.01, 0.005, and 0.002 for 476 streamgaging stations. Stream basin characteristics computed using spatial data and a geographic information system are used as explanatory variables in regional regression model equations for six physiographic regions to estimate regional annual exceedance probabilities at gaged and ungaged sites. Weighted peak-flow values that combine annual exceedance probabilities computed from gaging station data and from regional regression equations provide improved peak-flow estimates. Text, figures, and lists are provided summarizing selected peak-flow sites, delineated physiographic regions, peak-flow estimates, basin characteristics, regional regression model equations, error estimates, definitions, data sources, and candidate regression model equations. This study supersedes previous studies of peak flows in Virginia.

  12. GLOBAL PEAK ALIGNMENT FOR COMPREHENSIVE TWO-DIMENSIONAL GAS CHROMATOGRAPHY MASS SPECTROMETRY USING POINT MATCHING ALGORITHMS

    PubMed Central

    Deng, Beichuan; Kim, Seongho; Li, Hengguang; Heath, Elisabeth; Zhang, Xiang

    2016-01-01

    Comprehensive two-dimensional gas chromatography coupled with mass spectrometry (GC×GC-MS) has been used to analyze multiple samples in a metabolomics study. However, due to some uncontrollable experimental conditions, such as the differences in temperature or pressure, matrix effects on samples, and stationary phase degradation, there is always a shift of retention times in the two GC columns between samples. In order to correct the retention time shifts in GC×GC-MS, the peak alignment is a crucial data analysis step to recognize the peaks generated by the same metabolite in different samples. Two approaches have been developed for GC×GC-MS data alignment: profile alignment and peak matching alignment. However, these existing alignment methods are all based on a local alignment, resulting that a peak may not be correctly aligned in a dense chromatographic region where many peaks are present in a small region. False alignment will result in false discovery in the downstream statistical analysis. We, therefore, develop a global comparison based peak alignment method using point matching algorithm (PMA-PA) for both homogeneous and heterogeneous data. The developed algorithm PMA-PA first extracts feature points (peaks) in the chromatography and then searches globally the matching peaks in the consecutive chromatography by adopting the projection of rigid and non-rigid transformation. PMA-PA is further applied to two real experimental data sets, showing that PMA-PA is a promising peak alignment algorithm for both homogenous and heterogeneous data in terms of F1 score, although it uses only peak location information. PMID:27650662

  13. Continuous melting and ion chromatographic analyses of ice cores.

    PubMed

    Huber, T M; Schwikowski, M; Gäggele, H W

    2001-06-22

    A new method for determining concentrations of organic and inorganic ions in ice cores by continuous melting and contemporaneous ion chromatographic analyses was developed. A subcore is melted on a melting device and the meltwater produced is collected in two parallel sample loops and then analyzed simultaneously by two ion chromatographs, one for anions and one for cations. For most of the analyzed species, lower or equal blank values were achieved with the continuous melting and analysis technique compared to the conventional analysis. Comparison of the continuous melting and ion chromatographic analysis with the conventional analysis of a real ice core segment showed good agreement in concentration profiles and total amounts of ionic species. Thus, the newly developed method is well suited for ice core analysis and has the advantages of lower ice consumption, less time-consuming sample preparation and lower risk of contamination.

  14. Poor compensatory hyperventilation in morbidly obese women at peak exercise.

    PubMed

    Zavorsky, Gerald S; Murias, Juan M; Kim, Do Jun; Gow, Jennifer; Christou, Nicolas V

    2007-11-15

    This study was designed to compare differences in pulmonary gas exchange at rest and at peak exercise in two groups of women: (1) physically active, non-obese women and (2) women with morbid obesity. Fourteen morbidly obese women (body mass index or BMI=49+/-7 kg/m2; peak oxygen consumption or VO2 peak=14+/-2 ml/(kg min)) and 14 physically active non-obese women (BMI=22+/-2 kg/m2; VO2 peak=50+/-6 ml/(kg min)) performed an incremental, ramped exercise test to exhaustion on a cycle ergometer. Arterial blood was sampled at rest and at peak exercise. At rest, the alveolar to arterial oxygen partial pressure difference was 3x higher in the obese women (14+/-10 mmHg) compared to non-obese women (5+/-4 mmHg). Arterial carbon dioxide pressure (PaCO2) was identical in both groups at rest (37+/-4 mmHg). Only the non-obese women showed a decrease in PaCO2 rest to peak exercise (-5+/-3 mmHg). The slope between heart rate and VO2 during exercise was higher in the morbidly obese compared to non-obese women indicating that for the same absolute increase in VO2 a larger increase in heart rate is needed, demonstrating poorer cardiac efficiency in obese women. In conclusion, morbidly obese women have poorer exercise capacity, cardiac efficiency, and compensatory hyperventilation at peak exercise, and poorer gas exchange at rest compared to physically active, non-obese women.

  15. Quantitative analysis and chromatographic fingerprinting for the quality evaluation of Forsythia suspensa extract by HPLC coupled with photodiode array detector.

    PubMed

    Xia, Yonggang; Yang, Bingyou; Wang, Qiuhong; Liang, Jun; Wei, Youhe; Yu, Hedan; Zhang, Qingbo; Kuang, Haixue

    2009-12-01

    A simple and reproducible HPLC-photodiode array detector method has been described for evaluating and controlling quality of Forsythia suspensa extract (FSE). First, by analysis of chromatographic fingerprints, the similarities of chromatograms of FSE samples from the same pharmaceutical company exceeded 0.999, 0.997 and 0.960, respectively, although they were much lower from different pharmaceutical companies. Second, by further comparing many batches of extract chromatograph charts with the corresponding reference herb materials, the "common peaks" 3, 5, 7 and 10 were defined as "marker peaks", which were identified as (+)-pinoresinol-beta-D-glucoside, forsythiaside, phillyrin and phillygenin, respectively. Third, four "marker peaks" were simultaneously determined based on fingerprint chromatogram for further controlling the quality of FSE quantitatively. Namely, the newly developed method was successfully applied to analyze 38 batches of FSE samples supplied by three pharmaceutical factories, which showed acceptable linearity, intra-day precision (RSD<2.76%), inter-day precision (RSD<3.43%) and the average recovery rates in the range of (95.38+/-2.96)% to (101.60+/-3.08)%. At last, hierarchical clustering analysis and Bayes discriminant analysis statistical methods were used to classify and differentiate the 38 FSE samples to provide the basis for guiding reasonable use of FSE and controlling its quality better.

  16. Scope of partial least-squares regression applied to the enantiomeric composition determination of ketoprofen from strongly overlapped chromatographic profiles.

    PubMed

    Padró, Juan M; Osorio-Grisales, Jaiver; Arancibia, Juan A; Olivieri, Alejandro C; Castells, Cecilia B

    2015-07-01

    Valuable quantitative information could be obtained from strongly overlapped chromatographic profiles of two enantiomers by using proper chemometric methods. Complete separation profiles where the peaks are fully resolved are difficult to achieve in chiral separation methods, and this becomes a particularly severe problem in case that the analyst needs to measure the chiral purity, i.e., when one of the enantiomers is present in the sample in very low concentrations. In this report, we explore the scope of a multivariate chemometric technique based on unfolded partial least-squares regression, as a mathematical tool to solve this quite frequent difficulty. This technique was applied to obtain quantitative results from partially overlapped chromatographic profiles of R- and S-ketoprofen, with different values of enantioresolution factors (from 0.81 down to less than 0.2 resolution units), and also at several different S:R enantiomeric ratios. Enantiomeric purity below 1% was determined with excellent precision even from almost completely overlapped signals. All these assays were tested on the most demanding condition, i.e., when the minor peak elutes immediately after the main peak. The results were validated using univariate calibration of completely resolved profiles and the method applied to the determination of enantiomeric purity of commercial pharmaceuticals.

  17. Liquid chromatographic determination of leuco base in FD&C Blue No. 1.

    PubMed

    Scher, A L; Murray, H D

    1986-01-01

    Methods are described for the determination of leuco base in FD&C Blue No. 1 by reverse phase liquid chromatography and for the preparation and standardization of leuco base stock solution. The stock solution is prepared by reductive titration of the color with TiCl3. Solutions of the color and of leuco base are chromatographed by isocratic elution, which is followed by a wash and equilibration that can be omitted for screening. Peak area and height calibrations were linear. At the specification level, the 99% prediction limits were 5.00 +/- 0.14% (area) and 5.00 +/- 0.37% (height). Limits of determination were 0.29% (area) and 0.73% (height) at the 99.5% confidence level. Recoveries were 97-101% for leuco base added to FD&C Blue No. 1 at levels of 1-6%.

  18. [Derivative gas chromatographic analysis of fructooligosaccharide in fermented sucrose].

    PubMed

    Cai, W M; Liu, H; Sun, X J

    2000-01-01

    As a new sweetener, fructooligosaccharide is paid more and more attention for its health improvement property. It includes trisaccharide, tetrasaccharide and pentasaccharide, and can be produced from sucrose by the fermentation of microorganism. In order to analyze the content of fructooligosaccharide in fermented sugar by gas chromatography, fructooligosaccharide was transformed into trimethylsilyl derivatives. Based on the modified gas chromatograph SP2308, and under the chosen chromatographic conditions with 0.53 mm capillary column of OV-101, the contents of fructose, glucose, sucrose and fructooligosaccharide were determined by programmed temperature chromatography. The recovery of fructooligosaccharide was satisfactory.

  19. On-line gas chromatographic analysis of airborne particles

    DOEpatents

    Hering, Susanne V [Berkeley, CA; Goldstein, Allen H [Orinda, CA

    2012-01-03

    A method and apparatus for the in-situ, chemical analysis of an aerosol. The method may include the steps of: collecting an aerosol; thermally desorbing the aerosol into a carrier gas to provide desorbed aerosol material; transporting the desorbed aerosol material onto the head of a gas chromatography column; analyzing the aerosol material using a gas chromatograph, and quantizing the aerosol material as it evolves from the gas chromatography column. The apparatus includes a collection and thermal desorption cell, a gas chromatograph including a gas chromatography column, heated transport lines coupling the cell and the column; and a quantization detector for aerosol material evolving from the gas chromatography column.

  20. Different reactivities of amphetamines with N-methyl-bis(trifluoroacetamide) in heated gas chromatographic injectors.

    PubMed

    Hidvégi, E; Hideg, Zs; Somogyi, G P

    2008-03-01

    A fast gas chromatographic mass spectrometric method has been developed earlier for the determination of amphetamine derivatives in human serum and urine. For derivatization, N-methyl-bis(trifluoroacetamide) (MBTFA) was used. Derivatization was performed using an on-line mode, since 1 microl of MBTFA and 1 microl sample extract, dissolved in toluene were injected simultaneously. In this study, the reactivity of the several amphetamine type analytes with MBTFA was investigated. MBTFA used for flash derivatization was applied undiluted on the one hand and diluted 4--4096-fold with acetonitrile on the other hand. Studying several amphetamines in the test sample spiked at the same concentrations we found that they could be divided into 3 groups based on relative target ion peak areas as a function of MBTFA dilution. Group 1, containing only primary amines showed an early increase of the relative peak areas if we increased MBTFA concentration, where group 2 (mainly N-methyl secondary amines) showed that relative peak areas started to increase intensively at higher MBTFA concentrations. Finally, MDEA as an N-ethyl secondary amine, representing group 3, showed significant increase if only slightly diluted MBTFA was used as a flash reagent. This phenomenon can be explained mainly with the less and less reactivity of amine groups in the case of groups 2 and 3, compared to group 1. These findings could help to optimise analytical methods involving flash derivatization processes.

  1. A new method to evaluate the similarity of chromatographic fingerprints: weighted pearson product-moment correlation coefficient.

    PubMed

    Liu, Yongsuo; Meng, Qinghua; Chen, Rong; Wang, Jiansong; Jiang, Shumin; Hu, Yuzhu

    2004-01-01

    The Pearson product-moment correlation coefficient is being used to evaluate the similarity of the high-performance liquid chromatographic fingerprints of traditional Chinese medicine (TCM) in China. It is confirmed that a large range of peak areas produced the wrong results. A new algorithm concerning weighted Pearson product-moment correlation coefficient is proposed in this article. The results for both real cases and simulated data sets show that the weighted Pearson product-moment correlation coefficients allow relatively larger differences for large values, smaller differences for small values, and more reliable results than the unweighted Pearson product-moment correlation coefficients. Weight selection depends on the specific scientific problem.

  2. Improving accuracy in the quantitation of overlapping, asymmetric, chromatographie peaks by deconvolution: theory and application to coupled gas chromatography atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Johansson, M.; Berglund, M.; Baxter, D. C.

    1993-09-01

    Systematic errors in the measurement of overlapping asymmetric, Chromatographic peaks are observed using the perpendicular-drop and tangent-skimming algorithms incorporated in commercial integrators. The magnitude of such errors increases with the degree of tailing and differences in peak size, and was found to be as great as 80% for peak-area and 100% for peak-height measurements made on the smaller, second component of simulated, noise-free chromatograms containing peaks at a size ratio of 10 to 1. Initial deconvolution of overlapping peaks, by mathematical correction for asymmetry, leads to significant improvements in the accuracy of both peak-area and height measurements using the simple, perpendicular-drop algorithm. A comparison of analytical data for the separation and determination of three organolead species by coupled gas chromatography atomic absorption spectrometry using peak-height and area measurements also demonstrates the improved accuracy obtained following deconvolution. It is concluded that the deconvolution method described could be beneficial in a variety of Chromatographic applications where overlapping, asymmetric peaks are observed.

  3. Comparison of chromatographic ion-exchange resins. III. Strong cation-exchange resins.

    PubMed

    Staby, Arne; Sand, Maj-Britt; Hansen, Ronni G; Jacobsen, Jan H; Andersen, Line A; Gerstenberg, Michael; Bruus, Ulla K; Jensen, Inge Holm

    2004-04-23

    A comparative study was performed on strong cation-exchangers to investigate the pH dependence, efficiency, binding strength, particle size distribution, static and dynamic capacity, and SEM pictures of chromatographic resins. The resins tested included: SP Sepharose XL, Poros 50 HS, Toyopearl SP 550c, SP Sepharose BB, Source 30S, TSKGel SP-5PW-HR20, and Toyopearl SP 650c. Testing was performed with four different proteins: anti-FVII Mab (IgG), aprotinin, lysozyme, and myoglobin. Dependence of pH on retention was generally very low for proteins with high pI. An unexpected binding at pH 7.5 of anti-FVII Mab with pI < 7.5 was observed on several resins. Efficiency results show the expected trend of higher dependence of the plate height with increasing flow rate of soft resins compared to resins for medium and high-pressure operation. Determination of particle size distribution by two independent methods, Coulter counting and SEM, was in very good agreement. The mono-dispersed nature of Source 30S was confirmed. Binding to cation-exchange resins as a function of ionic strength varies depending on the specific protein. Generally, binding and elution at high salt concentration may be performed with Toyopearl SP 550c and Poros 50 HS, while binding and elution at low salt concentration may be performed with Toyopearl SP 650c. A very high binding capacity was obtained with SP Sepharose XL. Comparison of static capacity and dynamic capacity at 10% break-through shows in general approximately 50-80% utilisation of the total available capacity during chromatographic operation. A general good agreement was obtained between this study and data obtained by others. The results of this study may be used for selection of resins for testing in process development. The validity of experiments and results with model proteins were tested using human insulin precursor in pure state and in real feed-stock on Toyopearl SP 550c, SP Sepharose BB, and Toyopearl SP 650c. Results showed good

  4. Thermal Modulation Methods To Improve the Efficiency of a Gas Chromatograph

    NASA Technical Reports Server (NTRS)

    Valentin, J. R.; Dimandja, J. D.; Do, M. T.; Kaljurand, M.; Chang, Sherwood (Technical Monitor)

    1995-01-01

    Thermal modulation techniques can be used to improve capacity, resolution, and time of analysis of a gas chromatograph. Two of-the techniques developed in our laboratories include using a GC column to store a sample (sample storage system) and applying temperature programming directly onto the wall of a capillary column. The storage system developed allowed the continuous collection of a sample profile for about 3 hours and storing it for as long as 20 hours. Thereafter, the samples were eluted maintaining the individual characteristics of the components present in it. Moreover, temperature programming was done directly on a capillary column improving the time of analysis and resolution of a mixture containing light hydrocarbons.

  5. Validated spectrophotometric and chromatographic methods for simultaneous determination of ketorolac tromethamine and phenylephrine hydrochloride.

    PubMed

    Belal, T S; El-Kafrawy, D S; Mahrous, M S; Abdel-Khalek, M M; Abo-Gharam, A H

    2016-07-01

    This work describes five simple and reliable spectrophotometric and chromatographic methods for analysis of the binary mixture of ketorolac tromethamine (KTR) and phenylephrine hydrochloride (PHE). Method I is based on the use of conventional Amax and derivative spectrophotometry with the zero-crossing technique where KTR was determined using its Amax and (1)D amplitudes at 323 and 341nm respectively, while PHE was determined by measuring the (1)D amplitudes at 248.5nm. Method II involves the application of the ratio spectra derivative spectrophotometry. For KTR, 12μg/mL PHE was used as a divisor and the (1)DD amplitudes at 265nm were plotted against KTR concentrations; while - by using 4μg/mL KTR as divisor - the (1)DD amplitudes at 243.5nm were found proportional to PHE concentrations. Method III depends on ratio-difference measurement where the peak to trough amplitudes between 260 and 284nm were measured and correlated to KTR concentration. Similarly, the peak to trough amplitudes between 235 and 260nm in the PHE ratio spectra were recorded. For method IV, the two compounds were separated using Merck HPTLC sheets of silica gel 60 F254 and a mobile phase composed of chloroform/methanol/ammonia (70:30:2, by volume) followed by densitometric measurement of KTR and PHE spots at 320 and 278nm respectively. Method V depends on HPLC-DAD. Effective chromatographic separation was achieved using Zorbax eclipse plus C8 column (4.6×250mm, 5μm) with a mobile phase consisting of 0.05M o-phosphoric acid and acetonitrile (50:50, by volume) at a flow rate 1mL/min and detection at 313 and 274nm for KTR and PHE respectively. Analytical performance of the developed methods was statistically validated according to the ICH guidelines with respect to linearity, ranges, precision, accuracy, detection and quantification limits. The validated spectrophotometric and chromatographic methods were successfully applied to the simultaneous analysis of KTR and PHE in synthetic mixtures

  6. Partial least squares model and design of experiments toward the analysis of the metabolome of Jatropha gossypifolia leaves: Extraction and chromatographic fingerprint optimization.

    PubMed

    Pilon, Alan Cesar; Carnevale Neto, Fausto; Freire, Rafael Teixeira; Cardoso, Patrícia; Carneiro, Renato Lajarim; Da Silva Bolzani, Vanderlan; Castro-Gamboa, Ian

    2016-03-01

    A major challenge in metabolomic studies is how to extract and analyze an entire metabolome. So far, no single method was able to clearly complete this task in an efficient and reproducible way. In this work we proposed a sequential strategy for the extraction and chromatographic separation of metabolites from leaves Jatropha gossypifolia using a design of experiments and partial least square model. The effect of 14 different solvents on extraction process was evaluated and an optimized separation condition on liquid chromatography was estimated considering mobile phase composition and analysis time. The initial conditions of extraction using methanol and separation in 30 min between 5 and 100% water/methanol (1:1 v/v) with 0.1% of acetic acid, 20 μL sample volume, 3.0 mL min(-1) flow rate and 25°C column temperature led to 107 chromatographic peaks. After the optimization strategy using i-propanol/chloroform (1:1 v/v) for extraction, linear gradient elution of 60 min between 5 and 100% water/(acetonitrile/methanol 68:32 v/v with 0.1% of acetic acid), 30 μL sample volume, 2.0 mL min(-1) flow rate, and 30°C column temperature, we detected 140 chromatographic peaks, 30.84% more peaks compared to initial method. This is a reliable strategy using a limited number of experiments for metabolomics protocols.

  7. Climate change and peak demand for electricity: Evaluating policies for reducing peak demand under different climate change scenarios

    NASA Astrophysics Data System (ADS)

    Anthony, Abigail Walker

    This research focuses on the relative advantages and disadvantages of using price-based and quantity-based controls for electricity markets. It also presents a detailed analysis of one specific approach to quantity based controls: the SmartAC program implemented in Stockton, California. Finally, the research forecasts electricity demand under various climate scenarios, and estimates potential cost savings that could result from a direct quantity control program over the next 50 years in each scenario. The traditional approach to dealing with the problem of peak demand for electricity is to invest in a large stock of excess capital that is rarely used, thereby greatly increasing production costs. Because this approach has proved so expensive, there has been a focus on identifying alternative approaches for dealing with peak demand problems. This research focuses on two approaches: price based approaches, such as real time pricing, and quantity based approaches, whereby the utility directly controls at least some elements of electricity used by consumers. This research suggests that well-designed policies for reducing peak demand might include both price and quantity controls. In theory, sufficiently high peak prices occurring during periods of peak demand and/or low supply can cause the quantity of electricity demanded to decline until demand is in balance with system capacity, potentially reducing the total amount of generation capacity needed to meet demand and helping meet electricity demand at the lowest cost. However, consumers need to be well informed about real-time prices for the pricing strategy to work as well as theory suggests. While this might be an appropriate assumption for large industrial and commercial users who have potentially large economic incentives, there is not yet enough research on whether households will fully understand and respond to real-time prices. Thus, while real-time pricing can be an effective tool for addressing the peak load

  8. OpenChrom: a cross-platform open source software for the mass spectrometric analysis of chromatographic data

    PubMed Central

    2010-01-01

    Background Today, data evaluation has become a bottleneck in chromatographic science. Analytical instruments equipped with automated samplers yield large amounts of measurement data, which needs to be verified and analyzed. Since nearly every GC/MS instrument vendor offers its own data format and software tools, the consequences are problems with data exchange and a lack of comparability between the analytical results. To challenge this situation a number of either commercial or non-profit software applications have been developed. These applications provide functionalities to import and analyze several data formats but have shortcomings in terms of the transparency of the implemented analytical algorithms and/or are restricted to a specific computer platform. Results This work describes a native approach to handle chromatographic data files. The approach can be extended in its functionality such as facilities to detect baselines, to detect, integrate and identify peaks and to compare mass spectra, as well as the ability to internationalize the application. Additionally, filters can be applied on the chromatographic data to enhance its quality, for example to remove background and noise. Extended operations like do, undo and redo are supported. Conclusions OpenChrom is a software application to edit and analyze mass spectrometric chromatographic data. It is extensible in many different ways, depending on the demands of the users or the analytical procedures and algorithms. It offers a customizable graphical user interface. The software is independent of the operating system, due to the fact that the Rich Client Platform is written in Java. OpenChrom is released under the Eclipse Public License 1.0 (EPL). There are no license constraints regarding extensions. They can be published using open source as well as proprietary licenses. OpenChrom is available free of charge at http://www.openchrom.net. PMID:20673335

  9. On the ion chromatographic determination of S(IV)

    NASA Astrophysics Data System (ADS)

    Dasgupta, Purnendu K.

    Ion Chromatographie determination of S(IV) is described with special reference to the determination of SO 2(g) and/or aerosol S(IV) along with chloride, nitrate and sulfate in particulate matter. A method is presented for the baseline separation of the above species. The Chromatographic behavior of hydroxymethanesulfonate under various eluent conditions is discussed.

  10. [The gas chromatographic detection of acetylene in cadaveric material].

    PubMed

    Iablochkin, V D

    1999-01-01

    Acetylene traces were detected by gas chromatography in the cadaveric right crural muscle of a 30-year-old man dead from an explosion of an acetylene reservoir at a plant. Acetylene was identified using the absolute calibration method on 3 standard gas chromatographic columns, reaction gas chromatography, and acetylene "deduction" by silver sulfate on silicagel.

  11. Chromatographic profiles of Ginkgo biloba leaves and selected products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An LC-DAD-ESI/MS method was developed to obtain chromatographic profiles for the flavonoids and terpene lactones of Ginkgo biloba leaves and selected G. biloba products. The method was used to identify 46 glycosylated flavonols and flavones, 3 free flavonol aglycones, catechin, 10 biflavones, a dihy...

  12. Note on the chromatographic analyses of marine polyunsaturated fatty acids

    USGS Publications Warehouse

    Schultz, D.M.; Quinn, J.G.

    1977-01-01

    Gas-liquid chromatography was used to study the effects of saponification/methylation and thin-layer chromatographic isolation on the analyses of polyunsaturated fatty acids. Using selected procedures, the qualitative and quantitative distribution of these acids in marine organisms can be determined with a high degree of accuracy. ?? 1977 Springer-Verlag.

  13. Performance of chromatographic systems to model soil-water sorption.

    PubMed

    Hidalgo-Rodríguez, Marta; Fuguet, Elisabet; Ràfols, Clara; Rosés, Martí

    2012-08-24

    A systematic approach for evaluating the goodness of chromatographic systems to model the sorption of neutral organic compounds by soil from water is presented in this work. It is based on the examination of the three sources of error that determine the overall variance obtained when soil-water partition coefficients are correlated against chromatographic retention factors: the variance of the soil-water sorption data, the variance of the chromatographic data, and the variance attributed to the dissimilarity between the two systems. These contributions of variance are easily predicted through the characterization of the systems by the solvation parameter model. According to this method, several chromatographic systems besides the reference octanol-water partition system have been selected to test their performance in the emulation of soil-water sorption. The results from the experimental correlations agree with the predicted variances. The high-performance liquid chromatography system based on an immobilized artificial membrane and the micellar electrokinetic chromatography systems of sodium dodecylsulfate and sodium taurocholate provide the most precise correlation models. They have shown to predict well soil-water sorption coefficients of several tested herbicides. Octanol-water partitions and high-performance liquid chromatography measurements using C18 columns are less suited for the estimation of soil-water partition coefficients.

  14. Optimizing Chromatographic Separation: An Experiment Using an HPLC Simulator

    ERIC Educational Resources Information Center

    Shalliker, R. A.; Kayillo, S.; Dennis, G. R.

    2008-01-01

    Optimization of a chromatographic separation within the time constraints of a laboratory session is practically impossible. However, by employing a HPLC simulator, experiments can be designed that allow students to develop an appreciation of the complexities involved in optimization procedures. In the present exercise, a HPLC simulator from "JCE…

  15. Passive radio frequency peak power multiplier

    DOEpatents

    Farkas, Zoltan D.; Wilson, Perry B.

    1977-01-01

    Peak power multiplication of a radio frequency source by simultaneous charging of two high-Q resonant microwave cavities by applying the source output through a directional coupler to the cavities and then reversing the phase of the source power to the coupler, thereby permitting the power in the cavities to simultaneously discharge through the coupler to the load in combination with power from the source to apply a peak power to the load that is a multiplication of the source peak power.

  16. The relationship between peak height velocity and physical performance in youth soccer players.

    PubMed

    Philippaerts, Renaat M; Vaeyens, Roel; Janssens, Melissa; Van Renterghem, Bart; Matthys, Dirk; Craen, Rita; Bourgois, Jan; Vrijens, Jacques; Beunen, Guston; Malina, Robert M

    2006-03-01

    Longitudinal changes in height, weight and physical performance were studied in 33 Flemish male youth soccer players from the Ghent Youth Soccer Project. The players' ages at the start of the study ranged from 10.4 to 13.7 years, with a mean age of 12.2 +/- 0.7 years. Longitudinal changes were studied over a 5 year period. Peak height velocity and peak weight velocity were determined using non-smoothed polynomials. The estimations of peak height velocity, peak weight velocity and age at peak height velocity were 9.7 +/- 1.5 cm x year-1, 8.4 +/- 3.0 kg x year-1 and 13.8 +/- 0.8 years, respectively. Peak weight velocity occurred, on average, at the same age as peak height velocity. Balance, speed of limb movement, trunk strength, upper-body muscular endurance, explosive strength, running speed and agility, cardiorespiratory endurance and anaerobic capacity showed peak development at peak height velocity. A plateau in the velocity curves was observed after peak height velocity for upper-body muscular endurance, explosive strength and running speed. Flexibility exhibited peak development during the tear after peak height velocity. Trainers and coaches should be aware of the individual characteristics of the adolescent growth spurt and the training load should also be individualized at this time.

  17. Antioxidant capacities of seven flavonoid compounds isolated from pulp of acai fruit (Euterpe oleracea)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The pulp of açai fruit (Euterpe oleracea Mart.) has been demonstrated to exhibit extremely high antioxidant capacity. Seven major flavonoids were isolated from freeze-dried acai pulp by various chromatographic methods. Their structures were elucidated as orientin (1), homoorientin (2), vitexin (3), ...

  18. The geomorphic structure of the runoff peak

    NASA Astrophysics Data System (ADS)

    Rigon, R.; D'Odorico, P.; Bertoldi, G.

    2011-06-01

    This paper develops a theoretical framework to investigate the core dependence of peak flows on the geomorphic properties of river basins. Based on the theory of transport by travel times, and simple hydrodynamic characterization of floods, this new framework invokes the linearity and invariance of the hydrologic response to provide analytical and semi-analytical expressions for peak flow, time to peak, and area contributing to the peak runoff. These results are obtained for the case of constant-intensity hyetograph using the Intensity-Duration-Frequency (IDF) curves to estimate extreme flow values as a function of the rainfall return period. Results show that, with constant-intensity hyetographs, the time-to-peak is greater than rainfall duration and usually shorter than the basin concentration time. Moreover, the critical storm duration is shown to be independent of rainfall return period as well as the area contributing to the flow peak. The same results are found when the effects of hydrodynamic dispersion are accounted for. Further, it is shown that, when the effects of hydrodynamic dispersion are negligible, the basin area contributing to the peak discharge does not depend on the channel velocity, but is a geomorphic propriety of the basin. As an example this framework is applied to three watersheds. In particular, the runoff peak, the critical rainfall durations and the time to peak are calculated for all links within a network to assess how they increase with basin area.

  19. Origin of weak lensing convergence peaks

    NASA Astrophysics Data System (ADS)

    Liu, Jia; Haiman, Zoltán

    2016-08-01

    Weak lensing convergence peaks are a promising tool to probe nonlinear structure evolution at late times, providing additional cosmological information beyond second-order statistics. Previous theoretical and observational studies have shown that the cosmological constraints on Ωm and σ8 are improved by a factor of up to ≈2 when peak counts and second-order statistics are combined, compared to using the latter alone. We study the origin of lensing peaks using observational data from the 154 deg2 Canada-France-Hawaii Telescope Lensing Survey. We found that while high peaks (with height κ >3.5 σκ , where σκ is the rms of the convergence κ ) are typically due to one single massive halo of ≈1 015M⊙ , low peaks (κ ≲σκ ) are associated with constellations of 2-8 smaller halos (≲1 013M⊙ ). In addition, halos responsible for forming low peaks are found to be significantly offset from the line of sight towards the peak center (impact parameter ≳ their virial radii), compared with ≈0.25 virial radii for halos linked with high peaks, hinting that low peaks are more immune to baryonic processes whose impact is confined to the inner regions of the dark matter halos. Our findings are in good agreement with results from the simulation work by Yang et al. [Phys. Rev. D 84, 043529 (2011)].

  20. Multivariate data analysis to evaluate the fingerprint peaks responsible for the cytotoxic activity of Mallotus species.

    PubMed

    Tistaert, C; Chataigné, G; Dejaegher, B; Rivière, C; Nguyen Hoai, N; Chau Van, M; Quetin-Leclercq, J; Vander Heyden, Y

    2012-12-01

    The Mallotus genus comprises numerous species used as traditional medicines in oriental countries and provides scientists a broad basis in the search for pharmacologically active constituents. In this paper, the cytotoxicity of 39 Mallotus extracts, different in species, part of the plant used, origin, and harvest season, is evaluated combining cytotoxicity assays with fingerprint technology and data handling tools. At first, the antiproliferative activity of the plant extracts is analyzed both on a non-cancerous cell line (WI-38--human lung fibroblast) and on a cancerous cell line (HeLa human cervix carcinoma). The results are linked to a data set of high-performance liquid chromatographic fingerprint profiles of the samples using multivariate calibration techniques. The regression coefficients of the multivariate model are then evaluated to indicate those peaks potentially responsible for the cytotoxic activity of the Mallotus extracts. In a final step, the cytotoxic extracts are analyzed by HPLC-MS and the indicated peaks identified.

  1. Plant metabolomics: resolution and quantification of elusive peaks in liquid chromatography-mass spectrometry profiles of complex plant extracts using multi-way decomposition methods.

    PubMed

    Khakimov, Bekzod; Amigo, José Manuel; Bak, Søren; Engelsen, Søren Balling

    2012-11-30

    Previous studies on LC-MS metabolomic profiling of 127 F2 Barbarea vulgaris plants derived from a cross of parental glabrous (G) and pubescent (P) type, revealed four triterpenoid saponins (hederagenin cellobioside, oleanolic acid cellobioside, epihederagenin cellobioside, and gypsogenin cellobioside) that correlated with resistance of plants against the insect herbivore, Phyllotreta nemorum. In this study, for the first time, we demonstrate the efficiency of the multi-way decomposition method PARAllel FACtor analysis 2 (PARAFAC2) for exploring complex LC-MS data. PARAFAC2 enabled automated resolution and quantification of several elusive chromatographic peaks (e.g. overlapped, elution time shifted and low s/n ratio), which could not be detected and quantified by conventional chromatographic data analysis. Raw LC-MS data of 127 F2 B. vulgaris plants were arranged in a three-way array (elution time point×mass spectra×samples), divided into 17 different chromatographic intervals and each interval were individually modeled by PARAFAC2. Three main outputs of the PARAFAC2 models described: (1) elution time profile, (2) relative abundance, and (3) pure mass spectra of the resolved peaks modeled from each interval of the chromatographic data. PARAFAC2 scores corresponding to relative abundances of the resolved peaks were extracted and further used for correlation and partial least squares (PLS) analysis. A total of 71 PARAFAC2 components (which correspond to actual peaks, baselines and tails of neighboring peaks) were modeled from 17 different chromatographic retention time intervals of the LC-MS data. In addition to four previously known saponins, correlation- and PLS-analysis resolved five unknown saponin-like compounds that were significantly correlated with insect resistance. The method also enabled a good separation between resistant and susceptible F2 plants. PARAFAC2 spectral loadings corresponding to the pure mass spectra of chromatographic peaks matched well

  2. A novel ion-pairing chromatographic method for the simultaneous determination of both nicarbazin components in feed additives: chemometric tools for improving the optimization and validation.

    PubMed

    De Zan, María M; Teglia, Carla M; Robles, Juan C; Goicoechea, Héctor C

    2011-07-15

    The development, optimization and validation of an ion-pairing high performance liquid chromatography method for the simultaneous determination of both nicarbazin (NIC) components: 4,4'-dinitrocarbanilide (DNC) and 2-hydroxy-4,6-dimethylpyrimidine (HDP) in bulk materials and feed additives are described. An experimental design was used for the optimization of the chromatographic system. Four variables, including mobile phase composition and oven temperature, were analyzed through a central composite design exploring their contribution to analyte separation. Five responses: peak resolutions, HDP capacity factor, HDP tailing and analysis time, were modelled by using the response surface methodology and were optimized simultaneously by implementing the desirability function. The optimum conditions resulted in a mobile phase consisting of 10.0 mmol L(-1) of 1-heptanesulfonate, 20.0 mmol L(-1) of sodium acetate, pH=3.30 buffer and acetonitrile in a gradient system at a flow rate of 1.00 mL min(-1). Column was an INERSTIL ODS-3 (4.6 mm×150 mm, 5 μm particle size) at 40.0°C. Detection was performed at 300 nm by a diode array detector. The validation results of the method indicated a high selectivity and good precision characteristics, with RSD less than 1.0% for both components, both in intra and inter-assay precision studies. Linearity was proved for a range of 32.0-50.0 μg mL(-1) of NIC in sample solution. The recovery, studied at three different fortification levels, varied from 98.0 to 101.4 for HDP and from 99.1 to 100.2 for DNC. The applicability of the method was demonstrated by determining DNC and HDP content in raw materials and commercial formulations used for coccidiosis prevention. Assays results on real samples showed that considerable differences in molecular ratio DNC:HDP exist among them.

  3. Approaches to model the retention and peak profile in linear gradient reversed-phase liquid chromatography.

    PubMed

    Baeza-Baeza, J J; Ortiz-Bolsico, C; Torres-Lapasió, J R; García-Álvarez-Coque, M C

    2013-04-05

    The optimisation of the experimental conditions in gradient reversed-phase liquid chromatography requires reliable algorithms for the description of the retention and peak profile. As in isocratic elution, the linear relationship between the logarithm of the retention factor and the solvent contents is only acceptable in relatively small concentration ranges of modifier. However, more complex models may not allow an analytical integration of the general equation for gradient elution. Alternative approaches for modelling the retention in linear gradient elution are here proposed. Those based on the quadratic logarithmic model and a model proposed for normal liquid chromatography yielded accurate predictions of the retention time for a wide range of initial concentrations of organic modifier and gradient slopes, with errors usually below 1-2%. Based on the half-width changes of chromatographic peaks along one or more gradients, an approach is also reported to predict the peak profile with low errors (usually below 2-3%). The proposed approaches were applied to two sets of probe compounds (diuretics and flavonoids), eluted with acetonitrile-water gradients. The changes in retention and peak shape in isocratic and gradient elution are illustrated through diagrams that define triangular regions including all possible values of retention factors or peak half-widths (or widths) inside the selected working ranges.

  4. 21 CFR 862.2230 - Chromatographic separation material for clinical use.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Chromatographic separation material for clinical... Laboratory Instruments § 862.2230 Chromatographic separation material for clinical use. (a) Identification. A chromatographic separation material for clinical use is a device accessory (e.g., ion exchange absorbents,...

  5. 21 CFR 862.2230 - Chromatographic separation material for clinical use.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Chromatographic separation material for clinical... Laboratory Instruments § 862.2230 Chromatographic separation material for clinical use. (a) Identification. A chromatographic separation material for clinical use is a device accessory (e.g., ion exchange absorbents,...

  6. Mountain substitutability and peak load pricing of high alpine peaks as a management tool to reduce environmental damage: a contingent valuation study.

    PubMed

    Loomis, John B; Keske, Catherine M

    2009-04-01

    High alpine peaks throughout the world are under increasing environmental pressure from hikers, trekkers, and climbers. Colorado's "Fourteeners", peaks with summits above 14,000 feet are no exception. Most of these peaks have no entrance fees, and reach ecological and social carrying capacity on weekends. This paper illustrates how a series of dichotomous choice contingent valuation questions can be used to evaluate substitutability between different alpine peaks and quantify the price responsiveness to an entrance fee. Using this approach, we find that peak load pricing would decrease use of popular Fourteeners in Colorado by 22%. This reduction is due almost entirely to substitution, rather than income effects. There is also price inelastic demand, as 60% of the hikers find no substitution for their specific Fourteener at the varying cost increases posed in the survey. The no substitute group has a mean net benefit of $294 per hiker, per trip, considerably higher than visitor net benefits in most recreational use studies.

  7. Ion-exchange chromatographic protein refolding.

    PubMed

    Freydell, Esteban J; van der Wielen, Luuk; Eppink, Michel; Ottens, Marcel

    2010-11-12

    The application of ion-exchange (IEX) chromatography to protein refolding (IExR) has been successfully proven, as supported by various studies using different model proteins, ion-exchange media and flow configurations. Ion-exchange refolding offers a relatively high degree of process intensification, represented by the possibility of performing protein refolding, product purification and product concentration, in one unit operation. Besides its high degree of process intensification, IExR offers an additional set of key advantages including: spatial isolation of the bound protein molecules and the controllable change in chemical composition using gradients. Despite of the acknowledgement of the former advantages, the lack of mechanistic understanding on how they influence the process performance of the ion-exchange refolding reactor, limits the ability to exploit them in order to optimize the performance of the unit. This paper presents a quantitative analysis that assesses the effect that the spatial isolation and the urea gradient, have on the IExR performance, judged on the basis of the refolding yield (Y(N)) and the fractional mass recovery (f(Prot,Rec)). Additionally, this work discusses the effect of the protein load, the protein loading state (i.e., native, denatured, denatured and reduced (D&R)) and the adsorbent type on f(Prot,Rec). The presented work shows: (1) that the protein load has a direct effect on f(Prot,Rec), and the magnitude of this effect depends on the loading state of the protein solution and the adsorbent type; (2) that irrespectively of the type of adsorbent used, the saturation capacity of a denatured protein is less than the native protein and that this difference can be linked to differences in accessible binding surface area; (3) that there is a clear correlation between fractional surface coverage (θ) and f(Prot,Rec), indicating that the former could serve as a good descriptor to assess spatial isolation, and (4) that the urea

  8. Do dark matter halos explain lensing peaks?

    NASA Astrophysics Data System (ADS)

    Zorrilla Matilla, José Manuel; Haiman, Zoltán; Hsu, Daniel; Gupta, Arushi; Petri, Andrea

    2016-10-01

    We have investigated a recently proposed halo-based model, Camelus, for predicting weak-lensing peak counts, and compared its results over a collection of 162 cosmologies with those from N-body simulations. While counts from both models agree for peaks with S /N >1 (where S /N is the ratio of the peak height to the r.m.s. shape noise), we find ≈50 % fewer counts for peaks near S /N =0 and significantly higher counts in the negative S /N tail. Adding shape noise reduces the differences to within 20% for all cosmologies. We also found larger covariances that are more sensitive to cosmological parameters. As a result, credibility regions in the {Ωm,σ8} are ≈30 % larger. Even though the credible contours are commensurate, each model draws its predictive power from different types of peaks. Low peaks, especially those with 2 peaks (S /N >3 ). Our results confirm the importance of using a cosmology-dependent covariance with at least a 14% improvement in parameter constraints. We identified the covariance estimation as the main driver behind differences in inference, and suggest possible ways to make Camelus even more useful as a highly accurate peak count emulator.

  9. Training Lessons Learned from Peak Performance Episodes.

    ERIC Educational Resources Information Center

    Fobes, James L.

    A major challenge confronting the United States Army is to obtain optimal performance from both its human and machine resources. This study examines episodes of peak performance in soldiers and athletes. Three cognitive components were found to enable episodes of peak performance: psychological readiness (activating optimal arousal and emotion…

  10. The geomorphic structure of the runoff peak

    NASA Astrophysics Data System (ADS)

    Rigon, R.; D'Odorico, P.; Bertoldi, G.

    2011-01-01

    This paper develops a theoretical framework to investigate the core dependence of peak flows on the geomorphic properties of river basins. Based on the theory of transport by travel times, and simple hydrodynamic characterization of floods, this new framework invokes the linearity and invariance of the hydrologic response to provide analytical and semi-analitical expressions for peak flow, time to peak, and area contributing to the peak runoff. These results are obtained for the case of constant-intensity hyetograph using the Intensity-Duration-Frequency (IDF) curves to estimate extreme flow values as a function of the rainfall return period. Results show that, with constant-intensity hyetographs, the time-to-peak is greater than rainfall duration and usually shorter than the basin concentration time. Moreover, the critical storm duration is shown to be independent of rainfall return period. Further, it is shown that the basin area contributing to the peak discharge does not depend on the channel velocity, but is a geomorphic propriety of the basin. The same results are found when the effects of hydrodynamic dispersion are accounted for. As an example this framework is applied to three watersheds. In particular, the runoff peak, the critical rainfall durations and the time to peak are calculated for all links within a network to assess how they increase with basin area.

  11. The Boson peak in supercooled water

    PubMed Central

    Kumar, Pradeep; Wikfeldt, K. Thor; Schlesinger, Daniel; Pettersson, Lars G. M.; Stanley, H. Eugene

    2013-01-01

    We perform extensive molecular dynamics simulations of the TIP4P/2005 model of water to investigate the origin of the Boson peak reported in experiments on supercooled water in nanoconfined pores, and in hydration water around proteins. We find that the onset of the Boson peak in supercooled bulk water coincides with the crossover to a predominantly low-density-like liquid below the Widom line TW. The frequency and onset temperature of the Boson peak in our simulations of bulk water agree well with the results from experiments on nanoconfined water. Our results suggest that the Boson peak in water is not an exclusive effect of confinement. We further find that, similar to other glass-forming liquids, the vibrational modes corresponding to the Boson peak are spatially extended and are related to transverse phonons found in the parent crystal, here ice Ih. PMID:23771033

  12. Studies on Chromatographic Fingerprint and Fingerprinting Profile-Efficacy Relationship of Saxifraga stolonifera Meerb.

    PubMed

    Wu, Xing-Dong; Chen, Hua-Guo; Zhou, Xin; Huang, Ya; Hu, En-Ming; Jiang, Zheng-Meng; Zhao, Chao; Gong, Xiao-Jian; Deng, Qing-Fang

    2015-12-19

    This work investigated the spectrum-effect relationships between high performance liquid chromatography (HPLC) fingerprints and the anti-benign prostatic hyperplasia activities of aqueous extracts from Saxifraga stolonifera. The fingerprints of S. stolonifera from various sources were established by HPLC and evaluated by similarity analysis (SA), hierarchical clustering analysis (HCA) and principal component analysis (PCA). Nine samples were obtained from these 24 batches of different origins, according to the results of SA, HCA and the common chromatographic peaks area. A testosterone-induced mouse model of benign prostatic hyperplasia (BPH) was used to establish the anti-benign prostatic hyperplasia activities of these nine S. stolonifera samples. The model was evaluated by analyzing prostatic index (PI), serum acid phosphatase (ACP) activity, concentrations of serum dihydrotestosterone (DHT), prostatic acid phosphatase (PACP) and type II 5α-reductase (SRD5A2). The spectrum-effect relationships between HPLC fingerprints and anti-benign prostatic hyperplasia activities were investigated using Grey Correlation Analysis (GRA) and partial least squares regression (PLSR). The results showed that a close correlation existed between the fingerprints and anti-benign prostatic hyperplasia activities, and peak 14 (chlorogenic acid), peak 17 (quercetin 5-O-β-d-glucopyranoside) and peak 18 (quercetin 3-O-β-l-rhamno-pyranoside) in the HPLC fingerprints might be the main active components against anti-benign prostatic hyperplasia. This work provides a general model for the study of spectrum-effect relationships of S. stolonifera by combing HPLC fingerprints with a testosterone-induced mouse model of BPH, which can be employed to discover the principle components of anti-benign prostatic hyperplasia bioactivity.

  13. Countercurrent Chromatographic Separation of Proteins Using an Eccentric Coiled Column with Synchronous and Nonsynchronous Type-J Planetary Motions

    PubMed Central

    SHINOMIYA, Kazufusa; YOSHIDA, Kazunori; TOKURA, Koji; TSUKIDATE, Etsuhiro; YANAGIDAIRA, Kazuhiro; ITO, Yoichiro

    2015-01-01

    Protein separation was performed using the high-speed counter-current chromatograph (HSCCC) at both synchronous and nonsynchronous type-J planetary motions. The partition efficiency was evaluated with two different column configurations, eccentric coil and toroidal coil, on the separation of a set of stable protein samples including cytochrome C, myoglobin and lysozyme with a polymer phase system composed of 12.5% (w/w) polyethylene glycol 1000 and 12.5% (w/w) dibasic potassium phosphate. Better peak resolution was obtained by the eccentric coil than by the toroidal coil using either lower or upper phase as the mobile phase. The peak resolution was further improved using the eccentric coil by the nonsynchronous type-J planetary motion with the combination of 1066 rpm of column rotation and 1000 rpm of revolution. PMID:25765276

  14. Development and Validation of a Stability-Indicating Liquid Chromatographic Method for Estimating Olmesartan Medoxomil Using Quality by Design.

    PubMed

    Beg, Sarwar; Sharma, Gajanand; Katare, O P; Lohan, Shikha; Singh, Bhupinder

    2015-08-01

    The current studies entail systematic quality by design (QbD)-based development of a simple, rapid, sensitive and cost-effective stability-indicating method for the estimation of olmesartan medoxomil. Quality target method profile was defined and critical analytical attributes (CAAs) for the reverse-phase liquid chromatography method earmarked. Chromatographic separation accomplished on a C18 column using acetonitrile and water (containing 0.1% orthophosphoric acid, pH 3.5) in 40 : 60 (v/v) as mobile phase at a flow rate of 1.0 mL/min with UV detection at 243 nm. Risk assessment studies and screening studies facilitated comprehensive understanding of the factors affecting CAAs. The mobile phase ratio and flow rate were identified as critical method parameters (CMPs) and were systematically optimized using face-centered cubic design, evaluating for CAAs, namely peak area, retention time, theoretical plates and peak tailing. Statistical modelization was accomplished followed by response surface analysis for comprehending plausible interaction(s) among CMPs. Search for optimum solution was conducted through numerical and graphical optimization for demarcating the design space. Analytical method validation and subsequent forced degradation studies corroborated the method to be highly efficient for routine analysis of drug and its degradation products. The studies successfully demonstrate the utility of QbD approach for developing the highly sensitive liquid chromatographic method with enhanced method performance.

  15. Numerical method for the estimation of column radial heterogeneity and of the actual column efficiency from tailing peak profiles.

    PubMed

    Miyabe, Kanji; Guiochon, Georges

    2011-01-01

    It is probably impossible to prepare high-performance liquid chromatography (HPLC) columns that have a completely homogeneous packing structure. Many reports in the literature show that the radial distributions of the mobile phase flow velocity and the local column efficiency are not flat, even in columns considered as good. A degree of radial heterogeneity seems to be a common property of all HPLC columns and an important source of peak tailing, which prevents the derivation of accurate information on chromatographic behavior from a straightforward analysis of elution peak profiles. This work reports on a numerical method developed to derive from recorded peak profiles the column efficiency at the column center, the degree of column radial heterogeneity, and the polynomial function that best represents the radial distributions of the flow velocity and the column efficiency. This numerical method was applied to two concrete examples of tailing peak profiles previously described. It was demonstrated that this numerical method is effective to estimate important parameters characterizing the radial heterogeneity of chromatographic columns.

  16. Electrocapillary instability of magnetic fluid peak.

    PubMed

    Mkrtchyan, Levon; Zakinyan, Arthur; Dikansky, Yuri

    2013-07-23

    This Article presents an experimental study of the capillary electrostatic instability occurring under the effect of a constant electric field on a magnetic fluid individual peak. The peaks under study occur at disintegration of a magnetic fluid layer applied on a flat electrode surface under the effect of a perpendicular magnetic field. The electrocapillary instability shows itself as an emission of charged drops jets from the peak point in direction of the opposing electrode. The charged drops emission repeats periodically and results in the peak shape pulsations. It is shown that a magnetic field affects the electrocapillary instability occurrence regularities and can stimulate its development. The critical electric and magnetic field strengths at which the instability occurs have been measured; their dependence on the peak size is shown. The hysteresis in the system has been studied; it consists in that the charged drops emission stops at a lesser electric (or magnetic) field strength than that of the initial occurrence. The peak pulsations frequency depending on the magnetic and electric field strengths and on the peak size has been measured.

  17. Technical note: Comparison of chromatographic profile of glycomacropeptide from cheese whey isolated using different methods.

    PubMed

    Li, Esther W Y; Mine, Yoshinori

    2004-01-01

    Glycomacropeptide (GMP) has heterogeneous carbohydrates, and this attributes to its various biological activities. In this study, we compared the chromatographic profiles of GMP isolated by three methods (trichloracetic acid fractionation, ethanol precipitation, and ultrafiltration) from whey protein isolate (WPI). Seven sharp heterogeneous GMP peaks were eluted from GMP prepared by ethanol precipitation and ultrafiltration using Mono Q anionic chromatography, while only 5 peaks were seen in TCA treated sample. The TCA pretreatment recovered only sialo-GMP (glycosylated) and eliminated all contaminated proteins; however, the recovery rate was the lowest (6.7% of the initial WPI). Ethanol precipitation recovered 20.4% of GMP from WPI and 75.7% was glycosylated, but the heating process might lead to degradation of glycosidic residues. Ultrafiltration was found to be the most effective in recovering GMP. The recovery rate was 33.9% with 81.6% sialo-GMP. We concluded that carbohydrate profile of GMP varied widely and depended on the isolation method. Based on the high recovery of sialo-GMP, the combination of ultrafiltration and anionic chromatography might be a suitable and practical approach on an industrial scale.

  18. Use of micellar mobile phases for the chromatographic determination of melamine in dietetic supplements.

    PubMed

    Beltrán-Martinavarro, Beatriz; Peris-Vicente, Juan; Marco-Peiró, Sergio; Esteve-Romero, Josep; Rambla-Alegre, Maria; Carda-Broch, Samuel

    2012-01-07

    Melamine is a nitrogen-rich industrial chemical which is occasionally used to increase the apparent protein content of different products destined for human and animal consumption. In this work, a liquid chromatographic procedure that uses micellar mobile phases of sodium dodecyl sulfate (SDS) buffered at pH 3, a C18 column and UV detection is reported for the determination of melamine in dietetic supplements. Samples were reconstituted with a SDS solution and were directly injected, thus avoiding long extraction and experimental procedures. Melamine was eluted in less than 10 min with no interference by other compounds of the matrices. The optimum mobile phase composition was taken by a chemometrical approach that considers the retention factor, efficiency and peak shape. Validation was performed following the indications of the European Commission (Decision 2002/657/EC). The following parameters were considered: linearity (0.02-100 μg mL(-1); R(2) = 0.9996), intra- and inter-day precisions (<12.4%), accuracy (90.0-101.3%), and robustness (less than 9.8% and 5.1%, for retention time and peak area, respectively). The limits of detection and quantification were 9 and 20 ng mL(-1), respectively. Recoveries for several spiked samples were in the 85.8-114.3% range. These results indicate that the proposed methodology is useful for routine analysis of control quality of infant formula and adult dietetic supplements.

  19. Purge and trap with monolithic sorbent for gas chromatographic analysis of pesticides in honey.

    PubMed

    Chienthavorn, Orapin; Dararuang, Kanittha; Sasook, Anupop; Ramnut, Narumol

    2012-01-01

    Polydivinylbenzene (P-DVB) and silica monolithic materials were synthesised in capillaries and then used to adsorb nine organonitrogen pesticides extracted from honey. After adsorption, each monolith-capillary was connected to a gas chromatograph (GC) with nitrogen-phosphorous detector (NPD). The silica monolith gave better peak shape and intensity than the P-DVB monolith. Formulation of silica monolith with tetramethoxysilane (TMOS) as a sole initiator provided better separation and higher peak intensity, compared to those with methyltrimethoxysilane (MTMS) and (3:1) TMOS/MTMS initiators. The optimum internal diameter and length of silica monolith-capillary were 0.25 mm and 5 cm, respectively. The purge and trap conditions were optimised by purging with nitrogen and heating the honey sample solution at 100 °C for 60 min. Recovery of the method was in a range of 84.95-99.71% and the detection limits of the pesticides determined by using GC-NPD and GC-mass spectrometric detector (MSD) ranged between 0.36-1.75 and 0.13-0.25 ng g(-1), respectively.

  20. Optimisation of temperature-programmed gas chromatographic separation of organochloride pesticides by response surface methodology.

    PubMed

    D'Archivio, Angelo Antonio; Maggi, Maria Anna; Marinelli, Cristina; Ruggieri, Fabrizio; Stecca, Fabrizio

    2015-12-04

    A response surface methodology (RSM) approach is applied to optimise the temperature-programme gas-chromatographic separation of 16 organochloride pesticides, including 12 compounds identified as highly toxic chemicals by the Stockholm Convention on Persistent Organic Pollutants. A three-parameter relationship describing both linear and curve temperature programmes is derived adapting a model previously used in literature to describe concentration gradients in liquid chromatography with binary eluents. To investigate the influence of the three temperature profile descriptors (the starting temperature, the gradient duration and a shape parameter), a three-level full-factorial design of experiments is used to identify suitable combinations of the above variables spanning over a useful domain. Resolutions of adjacent peaks are the responses modelled by RSM using two alternative methods: a multi-layer artificial network (ANN) and usual polynomial regression. The proposed ANN-based approach permits to model simultaneously the resolutions of all the consecutive analyte pairs as a function of the temperature profile descriptors. Four critical pairs giving partially overlapped peaks are identified and multiresponse optimisation is carried out by analysing the surface plot of a global resolution defined as the average of the resolutions of the critical pairs. Descriptive/predictive performance and applicability of the ANN and polynomial RSM methods are compared and discussed.

  1. [High-performance liquid chromatography of peptide bioregulators, their fragments and derivatives. I. Chromatographic pattern of corticotropin fragments of Zorbax ODS sorbent].

    PubMed

    Grigor'ev, V D; Shats, V D; Brivkalne, L A; Chipens, G I

    1983-07-01

    The influence of acetonitrile concentration in the eluent and of the peptide hydrophobicity on the capacity factors has been studied. The equation is proposed that describes retention as a function of the eluent characteristics and the peptide composition. The hydrophobicity increments for -COOH, -NH2, and greater than CHCONH-fragments in the studied chromatographic system have been determined. The proposed model of peptide retention is useful for a prior evaluation of the eluent composition that is necessary to elute a compound at a given capacity factor. It can be also used for the qualitative interpretation of peptide chromatograms.

  2. Characterization of thermal desorption with the Deans-switch technique in gas chromatographic analysis of volatile organic compounds.

    PubMed

    Ou-Yang, Chang-Feng; Huang, Ying-Xue; Huang, Ting-Jyun; Chen, Yong-Shen; Wang, Chieh-Heng; Wang, Jia-Lin

    2016-09-02

    This study presents a novel application based on the Deans-switch cutting technique to characterize the thermal-desorption (TD) properties for gas chromatographic (GC) analysis of ambient volatile organic compounds (VOCs). Flash-heating of the sorbent bed at high temperatures to desorb trapped VOCs to GC may easily produce severe asymmetric or tailing GC peaks affecting resolution and sensitivity if care is not taken to optimize the TD conditions. The TD peak without GC separation was first examined for the quality of the TD peak by analyzing a standard gas mixture from C2 to C12 at ppb level. The Deans switch was later applied in two different stages. First, it was used to cut the trailing tail of the TD peak, which, although significantly improved the GC peak symmetry, led to more loss of the higher boiling compounds than the low boiling ones, thus suggesting compound discrimination. Subsequently, the Deans switch was used to dissect the TD peak into six 30s slices in series, and an uneven distribution in composition between the slices were found. A progressive decrease in low boiling compounds and increase in higher boiling ones across the slices indicated severe inhomogeneity in the TD profile. This finding provided a clear evidence to answer the discrimination problem found with the tail cutting approach to improve peak symmetry. Through the use of the innovated slicing method based on the Deans-switch cutting technique, optimization of TD injection for highly resolved, symmetric and non-discriminated GC peaks can now be more quantitatively assessed and guided.

  3. Estimation of peak winds from hourly observations

    NASA Technical Reports Server (NTRS)

    Graves, M. E.

    1973-01-01

    Two closely related methods to obtain estimates of the hourly peak wind at Cape Kennedy were compared by statistical tests. The methods evaluated the Monin-Obukhov stability length and the standard deviation of the hourly observed wind speed, so as to augment the latter quantity by F standard deviations. F is an optimized factor. A third method utilizing an optimized gust factor was also applied to the hourly wind. The latter procedure estimated 2952 peak winds with an rms error of 2.81 knots, an accuracy which was not surpassed by the other methods. Peak ground wind speed data were developed for use in space shuttle design operation analyses.

  4. Catalytically-Promoted Analyte Derivatization Inside a Gas Chromatographic Inlet

    PubMed Central

    Fowler, William K.; Gamble, Kelly J.; Wright, Amber R.

    2010-01-01

    Reported here is a preliminary assessment of the feasibility of catalyzing on-line derivatization reactions inside the inlet (i.e., the injection port) of a gas chromatograph (GC) with solid heterogeneous catalysts. The experiments described here entail the installation of candidate catalysts inside the GC inlet liner and the subsequent injection of analyte/reagent mixtures onto the catalyst beds. Two catalysts are identified, each of which clearly catalyzes one of the chosen model derivatization reactions in the inlet of a GC. This result supports our hypothesis that on-line derivatizations can, in principle, be reproducibly catalyzed inside the GC inlet by solid heterogeneous catalysts and that the presence of such catalysts in the inlet do not necessarily cause a serious loss of instrument performance or chromatographic efficiency. PMID:20822662

  5. Intercalibration of chromatographic methods for auxino phytodrugs in Solanaceae.

    PubMed

    Gennaro, M C; Marengo, E; Gianotti, V; Angioi, S; Copeta, G

    2003-04-18

    Three chromatographic methods are considered for the determination in Solanaceae of auxino-similar phytodrugs, so called because their structure resembles an auxine plant hormone. The phytodrugs studied were: 2,4-dichlorophenoxyacetic acid, 2,4-dichlorophenoxypropionic acid, 2,4-dichlorophenoxybutyric acid, 2-methyl-4-chlorophenoxyacetic acid, 2,4,5-trichlorophenoxyacetic acid, naphthylacetic acid and 2-naphthyloxyacetic acid. Three chromatographic methods, respectively based on ion-interaction HPLC, GC-MS with intra-injector derivatisation and CC-MS with pre-injection derivatisation, were developed, optimised and validated. A comparative discussion of the advantages/disadvantages of the methods suggests a strategy for their preferential use, that is essentially a function of the matrix complexity.

  6. Techniques of preparing plant material for chromatographic separation and analysis.

    PubMed

    Romanik, G; Gilgenast, E; Przyjazny, A; Kamiński, M

    2007-03-10

    This paper discusses preparation techniques of samples of plant material for chromatographic analysis. Individual steps of the procedures used in sample preparation, including sample collection from the environment or from tissue cultures, drying, comminution, homogenization, leaching, extraction, distillation and condensation, analyte enrichment, and obtaining the final extracts for chromatographic analysis are discussed. The techniques most often used for isolation of analytes from homogenized plant material, i.e., Soxhlet extraction, ultrasonic solvent extraction (sonication), accelerated solvent extraction, microwave-assisted extraction, supercritical-fluid extraction, steam distillation, as well as membrane processes are emphasized. Sorptive methods of sample enrichment and removal of interferences, i.e., solid-phase extraction, and solid-phase micro-extraction are also discussed.

  7. Micro-column plasma emission liquid chromatograph. [Patent application

    DOEpatents

    Gay, D.D.

    1982-08-12

    In a direct current plasma emission spectrometer for use in combination with a microcolumn liquid chromatograph, an improved plasma source unit is claimed. The plasma source unit includes a quartz capillary tube having an inlet means, outlet off gas means and a pair of spaced electrodes defining a plasma region in the tube. The inlet means is connected to and adapted to receive eluant of the liquid chromatograph along with a stream of plasma-forming gas. There is an opening through the wall of the capillary tube penetrating into the plasma region. A soft glass capillary light pipe is disposed at the opening, is connected to the spectrometer, and is adapted to transmit light passing from the plasma region to the spectrometer. There is also a source of electromotive force connected to the electrodes sufficient to initiate and sustain a plasma in the plasma region of the tube.

  8. Regulation of protein binding toward a ligand on chromatographic matrixes by masking and forced-releasing effects using thermoresponsive polymer.

    PubMed

    Yoshizako, Kimihiro; Akiyama, Yoshikatsu; Yamanaka, Hidenori; Shinohara, Yasuro; Hasegawa, Yukio; Carredano, Enrique; Kikuchi, Akihiko; Okano, Teruo

    2002-08-15

    A novel concept of affinity regulation based on masking and forced-releasing effects using a thermoresponsive polymer was elucidated. Affinity chromatographic matrixes were prepared using either poly(glycidyl methacrylate-co-ethyleneglycol dimethacrylate) or poly(glycidyl methacrylate-co-triethyleneglycol dimethacrylate) beads immobilized with ligand molecule, Cibacron Blue F3G-A (CB), together with poly(N-isopropylacrylamide) (PIPAAm), a polymer with a cloud point of 32 degrees C. Two different lengths of spacer molecules were used for the immobilization of CB while maintaining the PIPAAm size constant. Chromatographic analyses using bovine serum albumin as a model protein showed a clear correlation between spacer length and binding capacity at temperatures lower than the lower critical solution temperature (LCST) of PIPAAm. The binding capacity under the LCST was significantly reduced only when the calculated spacer length was shorter than the mean size of the extended PIPAAm. Furthermore, the adsorbed protein could be desorbed (released) from the matrix surface by lowering the temperature to below the LCST while maintaining other factors such as pH and ion strength. Selective recovery of human albumin from human sera was demonstrated using this newly developed thermoresponsive affinity column.

  9. Pharmacognostic Screening of Piper trichostachyon Fruits and its Comparative Analysis with Piper nigrum Using Chromatographic Techniques

    PubMed Central

    Upadhya, Vinayak; Pai, Sandeep R.; Ankad, Gireesh M.; Hegde, Harsha V.

    2016-01-01

    Background: Piper trichostachyon is a wild, endemic Piper species from Western Ghats of India. The folklore healers of Belagavi region use this plant, similar to Piper nigrum. Aims: The present study investigates the comparison between P. nigrum and P. trichostachyon using pharmacognostic parameters. Materials and Methods: Pharmacognostic evaluation was carried out in terms of morphological, microscopic characters, and phytochemical analysis using standard methods. Comparative physicochemical analysis between P. trichostachyon and P. nigrum was also carried out through estimation of micro-macro nutrients, high-performance thin layer chromatography (HPTLC) investigation and using piperine as a marker compound for reversed phase-ultra flow liquid chromatographic (RP-UFLC) technique. Results: P. trichostachyon grows in the forests, and the fruits are morphologically similar to P. nigrum fruits, so the name in Kannada “Kaadu Kalu menasu” (wild/forest black pepper). The microscopy revealed the presence of stone cells, starch grains, oil cells and globules, beaker cells, and yellowish brown pigment layer, parenchymatous cells. The presence of alkaloids, oil, and tannins were observed in P. trichostachyon fruits. The HPTLC studies visibly indicated differences among two species with 12 peaks and varied banding pattern. RP-UFLC results showed less amount of piperine in P. trichostachyon (0.05 ± 0.002 mg/g) than in P. nigrum (16.14 ± 0.807 mg/g). Conclusion: The study reports on pharmacognostic parameters of P. trichostachyon for the 1st time and will be useful for the identification and authentication. The comparative HPTLC and RP-UFLC studies resolve the differentiation impasse among two species. However, further biological efficacy studies are required to establish its use in traditional medicine. SUMMARY Piper trichostachyon grows in the forests, and the fruits are morphologically similar to Piper nigrum fruitsThe microscopy of P. trichostachyon revealed the

  10. High-Performance Liquid Chromatographic and High-Performance Thin-Layer Chromatographic Method for the Quantitative Estimation of Dolutegravir Sodium in Bulk Drug and Pharmaceutical Dosage Form.

    PubMed

    Bhavar, Girija B; Pekamwar, Sanjay S; Aher, Kiran B; Thorat, Ravindra S; Chaudhari, Sanjay R

    2016-01-01

    Simple, sensitive, precise, and specific high-performance liquid chromategraphic (HPLC) and high-performance thin-layer chromatographic (HPTLC) methods for the determination of dolutegravir sodium in bulk drug and pharmaceutical dosage form were developed and validated. In the HPLC method, analysis of the drug was carried out on the ODS C18 column (150 × 4.6 mm, 5 μm particle size) using a mixture of acetonitrile: water (pH 7.5) in the ratio of 80:20 v/v as the mobile phase at the flow rate 1 mL/min at 260 nm. This method was found to be linear in the concentration range of 5-35 μg/mL. The peak for dolutegravir sodium was observed at 3.0 ± 0.1 minutes. In the HPTLC method, analysis was performed on aluminum-backed plates pre-coated with silica gel G60 F254 using methanol: chloroform: formic acid in the proportion of 8:2:0.5 v/v/v as the mobile phase. This solvent system was found to give compact spots for dolutegravir sodium with the Rf value 0.77 ± 0.01. Densitometric analysis of dolutegravir sodium was carried out in the absorbance mode at 265 nm. Linear regression analysis showed good linearity with respect to peak area in the concentration range of 200-900 ng/spot. The methods were validated for precision, limit of detection (LOD), limit of quantitation (LOQ), accuracy, and specificity. Statistical analysis showed that both of the methods are repeatable and specific for the estimation of the said drug. The methods can be used for routine quality control analysis of dolutegravir sodium.

  11. Rayleigh light scattering detection of three α1-adrenoceptor antagonists coupled with high performance liquid chromatograph

    NASA Astrophysics Data System (ADS)

    Li, Ai Ping; Peng, Huanjun; Peng, Jing Dong; Zhou, Ming Qiong; Zhang, Jing

    2015-08-01

    Herein, a Rayleigh light-scattering (RLS) detection method combined with high performance liquid chromatograph (HPLC) without any post-column probe was developed for the separation and determination of three α1-adrenoceptor antagonists. The quantitative analysis is benefiting from RLS signal enhancement upon addition of methanol which induced molecular aggregation to form an hydrophobic interface between aggregates and water that produce a sort of superficial enhanced scattering effect. A good chromatographic separation among the compounds was achieved using a Gemini 5u C18 reversed phase column (250 mm × 4.6 mm; 4 μm) with a mobile phase consisting of methanol and ammonium acetate-formic acid buffer solution (25 mM; pH = 3.0) at the flow rate of 0.7 mL min-1. The RLS signal was monitored at λex = λem = 354 nm. A limit of detection (LOD) of 0.065-0.70 μg L-1 was reached and a linear range was found between peak height and concentration in the range of 0.75-15 μg L-1 for doxazosin mesylate (DOX), 0.075-3.0 μg L-1 for prazosin hydrochloride (PRH), and 0.25-5 μg L-1 for terazosin hydrochloride (TEH), with linear regression coefficients all above 0.999. Recoveries from spiked urine samples were 88.4-99.0% which is within acceptable limits. The proposed method is convenient, reliable and sensitive which has been used successfully in human urine samples.

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

    PubMed

    Ohira, Shin-Ichi; Kuhara, Kenta; Shigetomi, Aki; Yamasaki, Takayuki; Kodama, Yuko; Dasgupta, Purnendu K; Toda, Kei

    2014-10-31

    Chromatographic determination of organic acids is widely performed, but the matrix often calls for lengthy and elaborate sample preparation prior to actual analysis. Matrix components, e.g., proteins, non-ionics, lipids etc. are typically removed by a combination of centrifugation/filtration and solid phase extraction (SPE) that may include the use of ion-exchange media. Here we report the quantitative electrodialytic transfer of organic acids from complex samples to ultrapure water in seconds using cellulose membranes modified with N,N-dimethylaminoethyl methacrylate, which essentially eliminates the negative ζ-potential of a regenerated cellulose membrane surface. The transfer characteristics of the ion transfer device (ITD) were evaluated with linear carboxylic acids. While the ion transfer efficiencies may be affected by the acid dissociation constants, in most cases it is possible to achieve quantitative transfer under optimized device residence time (solution flow rate) and the applied voltage. In addition, the transfer efficiency was unaffected by the wide natural variation of pH represented in real samples. The approach was applied to organic acids in various samples, including red wine, considered to represent an especially difficult matrix. While quantitative transfer of the organic acids (as judged by agreement with standard pretreatment procedures involving SPE) was achieved, transfer of other matrix components was <5%. The processed samples could then be chromatographically analyzed in a straightforward manner. We used ion exclusion chromatography with direct UV detection; in treated samples; there was a dramatic reduction of the large early peaks observed compared to only 0.45μm membrane filtered samples.

  13. Development of micromachined preconcentrators and gas chromatographic separation columns by an electroless gold plating technology

    NASA Astrophysics Data System (ADS)

    Kuo, C.-Y.; Chen, P.-S.; Chen, H.-T.; Lu, C.-J.; Tian, W.-C.

    2017-03-01

    In this study, a simple process for fabricating a novel micromachined preconcentrator (μPCT) and a gas chromatographic separation column (μSC) for use in a micro gas chromatograph (μGC) using one photomask is described. By electroless gold plating, a high-surface-area gold layer was deposited on the surface of channels inside the μPCT and μSC. For this process, (3-aminopropyl) trimethoxysilane (APTMS) was used as a promoter for attaching gold nanoparticles on a silicon substrate to create a seed layer. For this purpose, a gold sodium sulfite solution was used as reagent for depositing gold to form heating structures. The microchannels of the μPCT and μSC were coated with the adsorbent and stationary phase, Tenax-TA and polydimethylsiloxane (DB-1), respectively. μPCTs were heated at temperatures greater than 280 °C under an applied electrical power of 24 W and a heating rate of 75 °C s‑1. Repeatable thermal heating responses for μPCTs were achieved; good linearity (R 2  >  0.9997) was attained at three heating rates for the temperature programme for the μSC (0.2, 0.5 and 1 °C s‑1). The volatile organic compounds (VOCs) toluene and m-xylene were concentrated over the μPCT by rapid thermal desorption (peak width of half height (PWHH)  <1.5 s) preconcentration factors for both VOCs are  >7900. The VOCs acetone, benzene, toluene, m-xylene and 1,3,5-trimethylbenzene were also separated on the μSC as evidenced by their different retention times (47–184 s).

  14. Rapid process development of chromatographic process using direct analysis in real time mass spectrometry as a process analytical technology tool.

    PubMed

    Yan, Binjun; Chen, Teng; Xu, Zhilin; Qu, Haibin

    2014-06-01

    The concept of quality by design (QbD) is widely applied in the process development of pharmaceuticals. However, the additional cost and time have caused some resistance about QbD implementation. To show a possible solution, this work proposed a rapid process development method, which used direct analysis in real time mass spectrometry (DART-MS) as a process analytical technology (PAT) tool for studying the chromatographic process of Ginkgo biloba L., as an example. The breakthrough curves were fast determined by DART-MS at-line. A high correlation coefficient of 0.9520 was found between the concentrations of ginkgolide A determined by DART-MS and HPLC. Based on the PAT tool, the impacts of process parameters on the adsorption capacity were discovered rapidly, which showed a decreased adsorption capacity with the increase of the flow rate. This work has shown the feasibility and advantages of integrating PAT into QbD implementation for rapid process development.

  15. The chromatographic behaviour of wasp venom kinin, kallidin and bradykinin.

    PubMed

    MATHIAS, A P; SCHACHTER, M

    1958-09-01

    Wasp venom kinin which has hitherto appeared to be homogeneous can be resolved by ionexchange chromatography into a single major and two minor components. These are indistinguishable by their action on smooth muscle and by their rapid inactivation by chymotrypsin. All three components of wasp kinin are chromatographically different from kallidin or bradykinin. The close similarity of the latter compounds is confirmed by their identical behaviour on an ion-exchange resin.

  16. Can enantiomers be separated in achiral chromatographic systems?

    NASA Astrophysics Data System (ADS)

    Davankov, V. A.

    2016-10-01

    Consideration of chromatography of a nonracemic mixture on an achiral sorbent from a stereochemical point of view allows the claim that partial separation of the excess enantiomer zone from the racemate zone is possible only with analytes capable of self-associating under the conditions of the chromatographic column. It is from these positions that features of this process can be explained and conditions for its maximal proceeding formulated.

  17. Metal-Organic Frameworks for Thin-Layer Chromatographic Applications.

    PubMed

    Schenk, Claudia; Kutzscher, Christel; Drache, Franziska; Helten, Stella; Senkovska, Irena; Kaskel, Stefan

    2017-01-25

    Preparation of thin-layer chromatographic (TLC) plates based on metal-organic frameworks (MOFs) as porous stationary phases is described. DUT-67 (DUT = Dresden University of Technology), a zirconium based MOF, was used in combination with a fluorescent indicator as stationary phase for analyzing a small selection of a wide spectrum of relevant analytes. The successful separation of benzaldehyde from trans-cinnamaldehyde and 4-aminophenol from 2-aminotoluene is reported as a model system using optimized eluent mixtures containing acetic acid.

  18. Amplification of postwildfire peak flow by debris

    USGS Publications Warehouse

    Kean, Jason W.; Mcguire, Luke; Rengers, Francis; Smith, Joel B.; Staley, Dennis M.

    2016-01-01

    In burned steeplands, the peak depth and discharge of postwildfire runoff can substantially increase from the addition of debris. Yet methods to estimate the increase over water flow are lacking. We quantified the potential amplification of peak stage and discharge using video observations of postwildfire runoff, compiled data on postwildfire peak flow (Qp), and a physically based model. Comparison of flood and debris flow data with similar distributions in drainage area (A) and rainfall intensity (I) showed that the median runoff coefficient (C = Qp/AI) of debris flows is 50 times greater than that of floods. The striking increase in Qp can be explained using a fully predictive model that describes the additional flow resistance caused by the emergence of coarse-grained surge fronts. The model provides estimates of the amplification of peak depth, discharge, and shear stress needed for assessing postwildfire hazards and constraining models of bedrock incision.

  19. Amplification of postwildfire peak flow by debris

    NASA Astrophysics Data System (ADS)

    Kean, J. W.; McGuire, L. A.; Rengers, F. K.; Smith, J. B.; Staley, D. M.

    2016-08-01

    In burned steeplands, the peak depth and discharge of postwildfire runoff can substantially increase from the addition of debris. Yet methods to estimate the increase over water flow are lacking. We quantified the potential amplification of peak stage and discharge using video observations of postwildfire runoff, compiled data on postwildfire peak flow (Qp), and a physically based model. Comparison of flood and debris flow data with similar distributions in drainage area (A) and rainfall intensity (I) showed that the median runoff coefficient (C = Qp/AI) of debris flows is 50 times greater than that of floods. The striking increase in Qp can be explained using a fully predictive model that describes the additional flow resistance caused by the emergence of coarse-grained surge fronts. The model provides estimates of the amplification of peak depth, discharge, and shear stress needed for assessing postwildfire hazards and constraining models of bedrock incision.

  20. Observing at Kitt Peak National Observatory.

    ERIC Educational Resources Information Center

    Cohen, Martin

    1981-01-01

    Presents an abridged version of a chapter from the author's book "In Quest of Telescopes." Includes personal experiences at Kitt Peak National Observatory, and comments on telescopes, photographs, and making observations. (SK)

  1. Tectonics, Climate and Earth's highest peaks

    NASA Astrophysics Data System (ADS)

    Robl, Jörg; Prasicek, Günther; Hergarten, Stefan

    2016-04-01

    Prominent peaks characterized by high relief and steep slopes are among the most spectacular morphological features on Earth. In collisional orogens they result from the interplay of tectonically driven crustal thickening and climatically induced destruction of overthickened crust by erosional surface processes. The glacial buzz-saw hypothesis proposes a superior status of climate in limiting mountain relief and peak altitude due to glacial erosion. It implies that peak altitude declines with duration of glacial occupation, i.e., towards high latitudes. This is in strong contrast with high peaks existing in high latitude mountain ranges (e.g. Mt. St. Elias range) and the idea of peak uplift due to isostatic compensation of spatially variable erosional unloading an over-thickened orogenic crust. In this study we investigate landscape dissection, crustal thickness and vertical strain rates in tectonically active mountain ranges to evaluate the influence of erosion on (latitudinal) variations in peak altitude. We analyze the spatial distribution of serval thousand prominent peaks on Earth extracted from the global ETOPO1 digital elevation model with a novel numerical tool. We compare this dataset to crustal thickness, thickening rate (vertical strain rate) and mean elevation. We use the ratios of mean elevation to peak elevation (landscape dissection) and peak elevation to crustal thickness (long-term impact of erosion on crustal thickness) as indicators for the influence of erosional surface processes on peak uplift and the vertical strain rate as a proxy for the mechanical state of the orogen. Our analysis reveals that crustal thickness and peak elevation correlate well in orogens that have reached a mechanically limited state (vertical strain rate near zero) where plate convergence is already balanced by lateral extrusion and gravitational collapse and plateaus are formed. On the Tibetan Plateau crustal thickness serves to predict peak elevation up to an altitude

  2. LNG production for peak shaving operations

    SciTech Connect

    Price, B.C.

    1999-07-01

    LNG production facilities are being developed as an alternative or in addition to underground storage throughout the US to provide gas supply during peak gas demand periods. These facilities typically involved a small liquefaction unit with a large LNG storage tank and gas sendout facilities capable of responding to peak loads during the winter. Black and Veatch is active in the development of LNG peak shaving projects for clients using a patented mixed refrigerant technology for efficient production of LNG at a low installed cost. The mixed refrigerant technology has been applied in a range of project sizes both with gas turbine and electric motor driven compression systems. This paper will cover peak shaving concepts as well as specific designs and projects which have been completed to meet this market need.

  3. Helping System Engineers Bridge the Peaks

    NASA Technical Reports Server (NTRS)

    Rungta, Neha; Tkachuk, Oksana; Person, Suzette; Biatek, Jason; Whalen, Michael W.; Castle, Joseph; Castle, JosephGundy-Burlet, Karen

    2014-01-01

    In our experience at NASA, system engineers generally follow the Twin Peaks approach when developing safety-critical systems. However, iterations between the peaks require considerable manual, and in some cases duplicate, effort. A significant part of the manual effort stems from the fact that requirements are written in English natural language rather than a formal notation. In this work, we propose an approach that enables system engineers to leverage formal requirements and automated test generation to streamline iterations, effectively "bridging the peaks". The key to the approach is a formal language notation that a) system engineers are comfortable with, b) is supported by a family of automated V&V tools, and c) is semantically rich enough to describe the requirements of interest. We believe the combination of formalizing requirements and providing tool support to automate the iterations will lead to a more efficient Twin Peaks implementation at NASA.

  4. Prediction of pesticides chromatographic lipophilicity from the computational molecular descriptors.

    PubMed

    Casoni, Dorina; Petre, Jana; David, Victor; Sârbu, Costel

    2011-02-01

    Quantitative structure-property relationship models were developed for the prediction of pesticides and some PAH compounds lipophilicity based on a wide set of computational molecular descriptors and a set of experimental chromatographic data. The chromatographic lipophilicity of pesticides has been evaluated by high-performance liquid chromatography (HPLC) using different chemically bonded (C18, C8, CN and Phenyl HPLC columns) stationary phases and two different organic modifiers (methanol and acetonitrile, respectively) in the mobile phase composition. Through a systematic study, by using the classic multivariate analysis, several quantitative structure-property/lipophilicity multi-dimensional models were established. Multiple linear regression and genetic algorithm for the variable subset selection were used. The internal and external statistical evaluation procedures revealed some appropriate models for the chromatographic lipophilicity prediction of pesticides. Moreover, the statistical parameters of regression and those obtained by applying t-test for the intercept (a(0)) and for the slope (a(1)) in order to evaluate relationship between experimental and predicted octanol-water partition coefficients in case of the test set compounds, revealed two statistically valid models that can be successfully used in lipophilicity prediction of pesticides.

  5. Studies on improved integrated membrane-based chromatographic process for bioseparation

    NASA Astrophysics Data System (ADS)

    Xu, Yanke

    To improve protein separation and purification directly from a fermentation broth, a novel membrane filtration-cum-chromatography device configuration having a relatively impermeable coated zone near the hollow fiber module outlet has been developed. The integrated membrane filtration-cum-chromatography unit packed with chromatographic beads on the shell side of the hollow fiber unit enjoys the advantages of both membrane filtration and chromatography; it allows one to load the chromatographic media directly from the fermentation broth or lysate and separate the adsorbed proteins through the subsequent elution step in a cyclic process. Interfacial polymerization was carried out to coat the bottom section of the hollow fiber membrane while leaving the rest of the hollow fiber membrane unaffected. Myoglobin (Mb), bovine serum albumin (BSA) and a-lactalbumin (a-LA) were used as model proteins in binary mixtures. Separation behaviors of binary protein mixtures were studied in devices using either an ultrafiltration (UF) membrane or a microfiltration (MF) membrane. Experimental results show that the breakthrough time and the protein loading capacities were dramatically improved after coating in both UF and MF modules. For a synthetic yeast fermentation broth feed, the Mb and a-LA elution profiles for the four consecutive cyclic runs were almost superimposable. Due to the lower transmembrane flux in this device plus the periodical washing-elution during the chromatographic separation, fouling was not a problem as it is in conventional microfiltration. A mathematical model describing the hydrodynamic and protein loading behaviors of the integrated device using UF membrane with a coated zone was developed. The simulation results for the breakthrough agree well with the experimental breakthrough curves. The optimal length of the coated zone was obtained from the simulation. A theoretical analysis of the protein mass transfer was performed using a diffusion-convection model

  6. Double peak sensory responses: effects of capsaicin.

    PubMed

    Aprile, I; Tonali, P; Stalberg, E; Di Stasio, E; Caliandro, P; Foschini, M; Vergili, G; Padua, L

    2007-10-01

    The aim of this study is to verify whether degeneration of skin receptors or intradermal nerve endings by topical application of capsaicin modifies the double peak response obtained by submaximal anodal stimulation. Five healthy volunteers topically applied capsaicin to the finger-tip of digit III (on the distal phalanx) four times daily for 4-5 weeks. Before and after local capsaicin applications, we studied the following electrophysiological findings: compound sensory action potential (CSAP), double peak response, sensory threshold and double peak stimulus intensity. Local capsaicin application causes disappearance or decrease of the second component of the double peak, which gradually increases after the suspension of capsaicin. Conversely, no significant differences were observed for CSAP, sensory threshold and double peak stimulus intensity. This study suggests that the second component of the double peak may be a diagnostic tool suitable to show an impairment of the extreme segments of sensory nerve fibres in distal sensory axonopathy in the early stages of damage, when receptors or skin nerve endings are impaired but undetectable by standard nerve conduction studies.

  7. Development of Chromatographic Fingerprints of Eurycoma longifolia (Tongkat Ali) Roots Using Online Solid Phase Extraction-Liquid Chromatography (SPE-LC).

    PubMed

    Zaini, Nor Nasriah; Osman, Rozita; Juahir, Hafizan; Saim, Norashikin

    2016-04-30

    E. longifolia is attracting interest due to its pharmacological properties and pro-vitality effects. In this study, an online SPE-LC approach using polystyrene divinyl benzene (PSDVB) and C18 columns was developed in obtaining chromatographic fingerprints of E. longifolia. E. longifolia root samples were extracted using pressurized liquid extraction (PLE) technique prior to online SPE-LC. The effects of mobile phase compositions and column switching time on the chromatographic fingerprint were optimized. Validation of the developed method was studied based on eurycomanone. Linearity was in the range of 5 to 50 µg∙mL(-1) (r² = 0.997) with 3.2% relative standard deviation of peak area. The developed method was used to analyze 14 E. longifolia root samples and 10 products (capsules). Selected chemometric techniques: cluster analysis (CA), discriminant analysis (DA), and principal component analysis (PCA) were applied to the fingerprint datasets of 37 selected peaks to evaluate the ability of the chromatographic fingerprint in classifying quality of E. longifolia. Three groups were obtained using CA. DA yielded 100% correlation coefficient with 19 discriminant compounds. Using PCA, E. longifolia root samples were clearly discriminated from the products. This study showed that the developed online SPE-LC method was able to provide comprehensive evaluation of E. longifolia samples for quality control purposes.

  8. Gas Chromatograph Method Optimization Trade Study for RESOLVE: 20-meter Column v. 8-meter Column

    NASA Technical Reports Server (NTRS)

    Huz, Kateryna

    2014-01-01

    RESOLVE is the payload on a Class D mission, Resource Prospector, which will prospect for water and other volatile resources at a lunar pole. The RESOLVE payload's primary scientific purpose includes determining the presence of water on the moon in the lunar regolith. In order to detect the water, a gas chromatograph (GC) will be used in conjunction with a mass spectrometer (MS). The goal of the experiment was to compare two GC column lengths and recommend which would be best for RESOLVE's purposes. Throughout the experiment, an Inficon Fusion GC and an Inficon Micro GC 3000 were used. The Fusion had a 20m long column with 0.25mm internal diameter (Id). The Micro GC 3000 had an 8m long column with a 0.32mm Id. By varying the column temperature and column pressure while holding all other parameters constant, the ideal conditions for testing with each column length in their individual instrument configurations were determined. The criteria used for determining the optimal method parameters included (in no particular order) (1) quickest run time, (2) peak sharpness, and (3) peak separation. After testing numerous combinations of temperature and pressure, the parameters for each column length that resulted in the most optimal data given my three criteria were selected. The ideal temperature and pressure for the 20m column were 95 C and 50psig. At this temperature and pressure, the peaks were separated and the retention times were shorter compared to other combinations. The Inficon Micro GC 3000 operated better at lower temperature mainly due to the shorter 8m column. The optimal column temperature and pressure were 70 C and 30psig. The Inficon Micro GC 3000 8m column had worse separation than the Inficon Fusion 20m column, but was able to separate water within a shorter run time. Therefore, the most significant tradeoff between the two column lengths was peak separation of the sample versus run time. After performing several tests, it was concluded that better

  9. A dynamic programming approach for the alignment of signal peaks in multiple gas chromatography-mass spectrometry experiments

    PubMed Central

    Robinson, Mark D; De Souza, David P; Keen, Woon Wai; Saunders, Eleanor C; McConville, Malcolm J; Speed, Terence P; Likić, Vladimir A

    2007-01-01

    Background Gas chromatography-mass spectrometry (GC-MS) is a robust platform for the profiling of certain classes of small molecules in biological samples. When multiple samples are profiled, including replicates of the same sample and/or different sample states, one needs to account for retention time drifts between experiments. This can be achieved either by the alignment of chromatographic profiles prior to peak detection, or by matching signal peaks after they have been extracted from chromatogram data matrices. Automated retention time correction is particularly important in non-targeted profiling studies. Results A new approach for matching signal peaks based on dynamic programming is presented. The proposed approach relies on both peak retention times and mass spectra. The alignment of more than two peak lists involves three steps: (1) all possible pairs of peak lists are aligned, and similarity of each pair of peak lists is estimated; (2) the guide tree is built based on the similarity between the peak lists; (3) peak lists are progressively aligned starting with the two most similar peak lists, following the guide tree until all peak lists are exhausted. When two or more experiments are performed on different sample states and each consisting of multiple replicates, peak lists within each set of replicate experiments are aligned first (within-state alignment), and subsequently the resulting alignments are aligned themselves (between-state alignment). When more than two sets of replicate experiments are present, the between-state alignment also employs the guide tree. We demonstrate the usefulness of this approach on GC-MS metabolic profiling experiments acquired on wild-type and mutant Leishmania mexicana parasites. Conclusion We propose a progressive method to match signal peaks across multiple GC-MS experiments based on dynamic programming. A sensitive peak similarity function is proposed to balance peak retention time and peak mass spectra similarities

  10. Quantitative structure-retention relationships of polycyclic aromatic hydrocarbons gas-chromatographic retention indices.

    PubMed

    Drosos, Juan Carlos; Viola-Rhenals, Maricela; Vivas-Reyes, Ricardo

    2010-06-25

    Polycyclic aromatic compounds (PAHs) are of concern in environmental chemistry and toxicology. In the present work, a QSRR study was performed for 209 previously reported PAHs using quantum mechanics and other sources descriptors estimated by different approaches. The B3LYP/6-31G* level of theory was used for geometrical optimization and quantum mechanics related variables. A good linear relationship between gas-chromatographic retention index and electronic or topologic descriptors was found by stepwise linear regression analysis. The molecular polarizability (alpha) and the second order molecular connectivity Kier and Hall index ((2)chi) showed evidence of significant correlation with retention index by means of important squared coefficient of determination, (R(2)), values (R(2)=0.950 and 0.962, respectively). A one variable QSRR model is presented for each descriptor and both models demonstrates a significant predictive capacity established using the leave-many-out LMO (excluding 25% of rows) cross validation method's q(2) cross-validation coefficients q(2)(CV-LMO25%), (obtained q(2)(CV-LMO25%) 0.947 and 0.960, respectively). Furthermore, the physicochemical interpretation of selected descriptors allowed detailed explanation of the source of the observed statistical correlation. The model analysis suggests that only one descriptor is sufficient to establish a consistent retention index-structure relationship. Moderate or non-significant improve was observed for quantitative results or statistical validation parameters when introducing more terms in predictive equation. The one parameter QSRR proposed model offers a consistent scheme to predict chromatographic properties of PAHs compounds.

  11. Effect of thermal desorption kinetics on vapor injection peak irregularities by a microscale gas chromatography preconcentrator.

    PubMed

    Seo, Jung Hwan; Liu, Jing; Fan, Xudong; Kurabayashi, Katsuo

    2012-08-07

    Microscale gas chromatography (μGC) is an emerging analytical technique for in situ analysis and on-site monitoring of volatile organic compounds (VOCs) in moderately complex mixtures. One of the critical subcomponents in a μGC system is a microfabricated preconcentrator (μ-preconcentrator), which enables detection of compounds existing in indoor/ambient air at low (~sub ppb) concentrations by enhancing their signals. The prevailing notion is that elution peak broadening and tailing phenomena resulting from undesirable conditions of a microfabricated separation column (μ-column) are the primary sources of poor chromatographic resolution. However, previous experimental results indicate that the resolution degradation still remains observed for a μ-column integrated with other μGC subcomponents even after setting optimal separation conditions. In this work, we obtain the evidence that the unoptimized μ-preconcentrator vapor release/injection performance significantly contributes to decrease the fidelity of μGC analysis using our state-of-the-art passive preconcentrator microdevice. The vapor release/injection performance is highly affected by the kinetics of the thermal desorption of compounds trapped in the microdevice. Decreasing the heating rate by 20% from the optimal rate of 90 °Cs(-1) causes a 340% increase in peak tailing as well as 70% peak broadening (30% peak height reduction) to the microscale vapor injection process.

  12. Experimental Confirmation of Isotope Fractionation in Thiomolybdates Using Ion Chromatographic Separation and Detection by Multicollector ICPMS.

    PubMed

    Kerl, Carolin F; Lohmayer, Regina; Bura-Nakić, Elvira; Vance, Derek; Planer-Friedrich, Britta

    2017-03-07

    Molybdenum (98)Mo/(95)Mo isotope ratios are a sediment paleo proxy for the redox state of the ancient ocean. Under sulfidic conditions, no fractionation between seawater and sediment should be observed if molybdate (MoO4(2-)) is quantitatively transformed to tetrathiomolybdate (MoS4(2-)) and precipitated. However, quantum mechanical calculations previously suggested that incomplete sulfidation could be associated with substantial fractionation. To experimentally confirm isotope fractionation in thiomolybdates, a new approach for determination of isotope ratios of individual thiomolybdate species was developed that uses chromatography (HPLC-UV) to separate individual thiomolybdates, collecting each peak and analyzing isotope ratios with multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). Using commercially available MoO4(2-) and MoS4(2-) standards, the method was evaluated and excellent reproducibility and accuracy were obtained. For species with longer retention times, complete chromatographic peaks had to be collected to avoid isotope fractionation within peaks. Isotope fractionation during formation of thiomolybdates could be experimentally proven for the first time in the reaction of MoO4(2-) with 20-fold or 50-fold excess of sulfide. The previously calculated isotope fractionation for MoS4(2-) was confirmed, and the result for MoO2S2(2-) was in the predicted range. Isotopic fractionation during MoS4(2-) transformation with pressurized air was dominated by kinetic fractionation. Further optimization and online-coupling of the HPLC-MC-ICPMS approach for determination of low concentrations in natural samples will greatly help to obtain more accurate species-selective isotope information.

  13. Predicting Peak Flows following Forest Fires

    NASA Astrophysics Data System (ADS)

    Elliot, William J.; Miller, Mary Ellen; Dobre, Mariana

    2016-04-01

    Following forest fires, peak flows in perennial and ephemeral streams often increase by a factor of 10 or more. This increase in peak flow rate may overwhelm existing downstream structures, such as road culverts, causing serious damage to road fills at stream crossings. In order to predict peak flow rates following wildfires, we have applied two different tools. One is based on the U.S.D.A Natural Resource Conservation Service Curve Number Method (CN), and the other is by applying the Water Erosion Prediction Project (WEPP) to the watershed. In our presentation, we will describe the science behind the two methods, and present the main variables for each model. We will then provide an example of a comparison of the two methods to a fire-prone watershed upstream of the City of Flagstaff, Arizona, USA, where a fire spread model was applied for current fuel loads, and for likely fuel loads following a fuel reduction treatment. When applying the curve number method, determining the time to peak flow can be problematic for low severity fires because the runoff flow paths are both surface and through shallow lateral flow. The WEPP watershed version incorporates shallow lateral flow into stream channels. However, the version of the WEPP model that was used for this study did not have channel routing capabilities, but rather relied on regression relationships to estimate peak flows from individual hillslope polygon peak runoff rates. We found that the two methods gave similar results if applied correctly, with the WEPP predictions somewhat greater than the CN predictions. Later releases of the WEPP model have incorporated alternative methods for routing peak flows that need to be evaluated.

  14. Representation of Solar Capacity Value in the ReEDS Capacity Expansion Model

    SciTech Connect

    Sigrin, B.; Sullivan, P.; Ibanez, E.; Margolis, R.

    2014-03-01

    An important issue for electricity system operators is the estimation of renewables' capacity contributions to reliably meeting system demand, or their capacity value. While the capacity value of thermal generation can be estimated easily, assessment of wind and solar requires a more nuanced approach due to the resource variability. Reliability-based methods, particularly assessment of the Effective Load-Carrying Capacity, are considered to be the most robust and widely-accepted techniques for addressing this resource variability. This report compares estimates of solar PV capacity value by the Regional Energy Deployment System (ReEDS) capacity expansion model against two sources. The first comparison is against values published by utilities or other entities for known electrical systems at existing solar penetration levels. The second comparison is against a time-series ELCC simulation tool for high renewable penetration scenarios in the Western Interconnection. Results from the ReEDS model are found to compare well with both comparisons, despite being resolved at a super-hourly temporal resolution. Two results are relevant for other capacity-based models that use a super-hourly resolution to model solar capacity value. First, solar capacity value should not be parameterized as a static value, but must decay with increasing penetration. This is because -- for an afternoon-peaking system -- as solar penetration increases, the system's peak net load shifts to later in the day -- when solar output is lower. Second, long-term planning models should determine system adequacy requirements in each time period in order to approximate LOLP calculations. Within the ReEDS model we resolve these issues by using a capacity value estimate that varies by time-slice. Within each time period the net load and shadow price on ReEDS's planning reserve constraint signals the relative importance of additional firm capacity.

  15. Estimating peak discharges of small, rural streams in Massachusetts

    USGS Publications Warehouse

    Wandle, S. William

    1983-01-01

    Floodflows on natural-flow streams in Massachusetts with drainage areas between 0.25 square miles and 260 square miles may be estimated from drainage area, main-channel slope, mean basin elevation, and the area of swamps, lakes, and ponds. Multiple-regression techniques were used to define the relationship between a suite of basin and climatic characteristics and flood peaks in three flood-frequency regions at a total of 95 sites. Station flood-frequency data were computed following guidelines in Bulletin 17A of the U.S. Water Resources Council. The frequency analyses are based upon weighted skew values, adjustments for high and low outliers, and historic peak data. Regression equations for estimation of peak discharges for 0.5, 0.2, 0.1, 0.04, 0.02, and 0.01 exceedance probabilities are provided for ungaged sites. An improved sample of flood peaks and gaging stations and the definition of three flood-frequency regions reduced the standard errors of estimate by about 5 percent over those for the 1977 relations. Included in this analysis were the synthetic flood-frequency data at 8 sites computed using historic climatic data and 10 parameters optimized by calibration of the U.S. Geological Survey's rainfall-runoff model with storm data observed over 11 years. The equations are applicable to streams unaffected by regulation where the usable manmade storage is less than 4.5 million cubic feet per square mile, or by diversions or urbanization. The equations are restricted to sites where the basin indices are within a specified range outside of eastern Plymouth, Barnstable, Dukes, or Nantucket Counties. In these areas, the available data do not adequately define the influence of high infiltration and storage capacities of drainage basins on floodflows.

  16. New liquid chromatographic-chemometric approach for the determination of sunset yellow and tartrazine in commercial preparation.

    PubMed

    Dinç, Erdal; Aktaş, A Hakan; Ustündağ, Ozgür

    2005-01-01

    A new liquid chromatographic (LC)-chemometric approach was developed for the determination of sunset yellow (SUN) and tartrazine (TAR) in commercial preparations. This approach uses LC and chemometric calibration methods, i.e., classical least-squares (CLS), principal component regression (PCR), and partial-least squares (PLS), simultaneously. The combined LC-chemometric approaches, denoted as LC-CLS, LC-PCR, and LC-PLS, are based on photodiode array (PDA) detection at multiple wavelengths. Optimum chromatographic separation of SUN and TAR with allura red as the internal standard (IS) was obtained by using a Waters Symmetry C18 column, 5 microm, 4.6 x 250 mm, and 0.2 M acetate buffer (pH 5)-acetonitrile-methano-bidistilled water (55 + 20 + 15 + 10, v/v) as the mobile phase at a flow rate of 1.9 mL/min. The LC data sets consisting of the ratios of analyte peak areas to the IS peak area were obtained by using PDA detection at 5 wavelengths (465, 470, 475, 480, and 485 nm). LC-chemometric calibrations for SUN and TAR were separately constructed by using the relationship between the peak-area ratio and the training sets for each colorant. LC-chemometric approaches were tested for different synthetic mixtures containing SUN and TAR in the presence of the IS. These LC-chemometric calibrations were applied to a commercial preparation of the 2 colorants. The experimental results of the LC-chemometric approaches were compared with those obtained by a developed classical LC method using single-wavelength detection.

  17. Quality evaluation of Shenmaidihuang Pills based on the chromatographic fingerprints and simultaneous determination of seven bioactive constituents.

    PubMed

    Liu, Sifei; Zhang, Guangrui; Qiu, Ying; Wang, Xiaobo; Guo, Lihan; Zhao, Yanxin; Tong, Meng; Wei, Lan; Sun, Lixin

    2016-12-01

    In this study, we aimed to establish a comprehensive and practical quality evaluation system for Shenmaidihuang pills. A simple and reliable high-performance liquid chromatography coupled with photodiode array detection method was developed both for fingerprint analysis and quantitative determination. In fingerprint analysis, relative retention time and relative peak area were used to identify the common peaks in 18 samples for investigation. Twenty one peaks were selected as the common peaks to evaluate the similarities of 18 Shenmaidihuang pills samples with different manufacture dates. Furthermore, similarity analysis was applied to evaluate the similarity of samples. Hierarchical cluster analysis and principal component analysis were also performed to evaluate the variation of Shenmaidihuang pills. In quantitative analysis, linear regressions, injection precisions, recovery, repeatability and sample stability were all tested and good results were obtained to simultaneously determine the seven identified compounds, namely, 5-hydroxymethylfurfural, morroniside, loganin, paeonol, paeoniflorin, psoralen, isopsoralen in Shenmaidihuang pills. The contents of some analytes in different batches of samples indicated significant difference, especially for 5-hydroxymethylfurfural. So, it was concluded that the chromatographic fingerprint method obtained by high-performance liquid chromatography coupled with photodiode array detection associated with multiple compounds determination is a powerful and meaningful tool to comprehensively conduct the quality control of Shenmaidihuang pills.

  18. Development of chromatographic methods for the determination of genotoxic impurities in cloperastine fendizoate.

    PubMed

    García, Antonia; Rupérez, Francisco J; Ceppa, Florencia; Pellati, Federica; Barbas, Coral

    2012-03-05

    The classification of an impurity of a drug substance as genotoxic means that the "threshold of toxicological concern" (TTC) value of 1.5 μg/day intake, considered to be associated with an acceptable risk, should be the admissible limit in the raw material and that leads to new analytical challenges. In this study, reliable chromatographic methods were developed and applied as limit tests for the control of three genotoxic impurities (GTIs) in cloperastine fendizoate, drug widely used as an antitussive active pharmaceutical ingredient (API). In particular, GC-MS was applied to the determination of one alkyl halide (2-chloroethanol, 2-CE), while HPLC-DAD was selected for the analysis of two sulfonate esters (methyl p-toluenesulfonate, MPTS, and 2-chloroethyl p-toluenesulfonate, CEPTS). Regarding GC-MS, strong anion-exchange (SAX)-SPE was applied to remove fendizoate from the sample solutions, due its low volatility and its high amount in the raw material. The GC-MS analysis was performed on a Factor Four VF-23 ms capillary column (30 m × 0.25 mm I.D., film thickness 0.25 μm, Varian). Single ion-monitoring (SIM) detection mode was set at m/z 80. In the case of HPLC-DAD, a suitable optimization of the chromatographic conditions was carried out in order to obtain a good separation of the impurity peaks from the drug substance peaks. The optimized method utilizes a SymmetryShield RP(8) column (250 mm × 4.6 mm, 5 μm, Waters) kept at 50°C, with phosphate buffer (pH 3.0; 10 mM)-methanol (containing 10% ACN) (45:55, v/v) as the mobile phase, at the flow-rate of 1.7 mL/min and UV detection at 227 nm. The required sensitivity level was achieved by injecting 80 μL of sample solution, purified from fendizoate by SAX-SPE, followed by a 1:1 (v/v) dilution of the SPE eluate with water. For both GC-MS and HPLC-DAD, the method validation was performed in relation to specificity and limit of detection (LOD), as required by ICH guidelines in relation to limit assays. The

  19. SPANISH PEAKS WILDERNESS STUDY AREA, COLORADO.

    USGS Publications Warehouse

    Budding, Karin E.; Kluender, Steven E.

    1984-01-01

    A geologic and geochemical investigation and a survey of mines and prospects were conducted to evaluate the mineral-resource potential of the Spanish Peaks Wilderness Study Area, Huerfano and Las Animas Counties, in south-central Colorado. Anomalous gold, silver, copper, lead, and zinc concentrations in rocks and in stream sediments from drainage basins in the vicinity of the old mines and prospects on West Spanish Peak indicate a substantiated mineral-resource potential for base and precious metals in the area surrounding this peak; however, the mineralized veins are sparse, small in size, and generally low in grade. There is a possibility that coal may underlie the study area, but it would be at great depth and it is unlikely that it would have survived the intense igneous activity in the area. There is little likelihood for the occurrence of oil and gas because of the lack of structural traps and the igneous activity.

  20. The PEAK experience in South Carolina

    SciTech Connect

    1998-11-01

    The PEAK Institute was developed to provide a linkage for formal (schoolteachers) and nonformal educators (extension agents) with agricultural scientists of Clemson University`s South Carolina Agricultural Experiment Station System. The goal of the Institute was to enable teams of educators and researchers to develop and provide PEAK science and math learning experiences related to relevant agricultural and environmental issues of local communities for both classroom and 4-H Club experiences. The Peak Institute was conducted through a twenty day residential Institute held in June for middle school and high school teachers who were teamed with an Extension agent from their community. These educators participated in hands-on, minds-on sessions conducted by agricultural researchers and Clemson University Cooperative Extension specialists. Participants were given the opportunity to see frontier science being conducted by scientists from a variety of agricultural laboratories.

  1. Separating Peaks in X-Ray Spectra

    NASA Technical Reports Server (NTRS)

    Nicolas, David; Taylor, Clayborne; Wade, Thomas

    1987-01-01

    Deconvolution algorithm assists in analysis of x-ray spectra from scanning electron microscopes, electron microprobe analyzers, x-ray fluorescence spectrometers, and like. New algorithm automatically deconvolves x-ray spectrum, identifies locations of spectral peaks, and selects chemical elements most likely producing peaks. Technique based on similarities between zero- and second-order terms of Taylor-series expansions of Gaussian distribution and of damped sinusoid. Principal advantage of algorithm: no requirement to adjust weighting factors or other parameters when analyzing general x-ray spectra.

  2. A validated stability-indicating liquid chromatographic method for the determination of retapamulin in topical dosage form.

    PubMed

    Nalwade, Santaji; Reddy, Vangala Ranga

    2014-03-01

    A sensitive, stability-indicating reversed-phase high-performance liquid chromatographic method is developed and validated for the quantitative determination of retapamulin in topical dosage form. The chromatographic separation is achieved by using a C18 column (XTerra RP 18 250 × 4.6 mm, 5 µm) at 30°C. The mobile phase comprises a mixture of 0.05M potassium dihydrogen phosphate buffer (pH 6.1), acetonitrile and methanol in the ratio of 35:50:15 (v/v/v). The flow rate is set at 1.0 mL/min and chromatograms are extracted at 243 nm using a photodiode array detector. The method is validated with respect to linearity, accuracy, precision, robustness and forced degradation studies, which further prove the stability-indicating supremacy of the method. During forced degradation studies, retapamulin is observed to be labile to oxidative and base hydrolysis stress and stable in thermal, photolytic and acid hydrolysis stress. The degradation products are well separated from the retapamulin peak, thus proving the stability-indicating superiority of the method. The method is found to be sensitive for retapamulin, with a detection limit of 25 ng/mL and a quantification limit of 80 ng/mL. The proposed method is found to be very sensitive and accurate for the determination of retapamulin in topical dosage form. The method is also demonstrated to be robust, because it is resistant to small variations of chromatographic variables such as pH, mobile phase composition, flow rate and column temperature.

  3. An automated multidimensional preparative gas chromatographic system for isolation and enrichment of trace amounts of xenon from ambient air.

    PubMed

    Larson, Tuula; Östman, Conny; Colmsjö, Anders

    2011-04-01

    The monitoring of radioactive xenon isotopes is one of the principal methods for the detection of nuclear explosions in order to identify clandestine nuclear testing. In this work, a miniaturized, multiple-oven, six-column, preparative gas chromatograph was constructed in order to isolate trace quantities of radioactive xenon isotopes from ambient air, utilizing nitrogen as the carrier gas. The multidimensional chromatograph comprised preparative stainless steel columns packed with molecular sieves, activated carbon, and synthetic carbon adsorbents (e.g., Anasorb®-747 and Carbosphere®). A combination of purification techniques--ambient adsorption, thermal desorption, back-flushing, thermal focusing, and heart cutting--was selectively optimized to produce a well-defined xenon peak that facilitated reproducible heart cutting and accurate quantification. The chromatographic purification of a sample requires approximately 4 h and provides complete separation of xenon from potentially interfering components (such as water vapor, methane, carbon dioxide, and radon) with recovery and accuracy close to 100%. The preparative enrichment process isolates and concentrates a highly purified xenon gas fraction that is suitable for subsequent ultra-low-level γ-, ß/γ-spectroscopic or high-resolution mass spectrometric measurement (e.g., to monitor the gaseous fission products of nuclear explosions at remote locations). The Xenon Processing Unit is a free-standing, relatively lightweight, and transportable system that can be interfaced to a variety of sampling and detection systems. It has a relatively inexpensive, rugged, and compact modular (19-inch rack) design that provides easy access to all parts for maintenance and has a low power requirement.

  4. Reversed-phase liquid chromatographic determination of two manufacturing intermediates in D&C Red No. 34 and its lakes.

    PubMed

    Harp, Bhakti Petigara; Barrows, Julie N

    2009-01-01

    A reversed-phase LC method was developed to determine two manufacturing intermediates in the monosulfo monoazo color additive D&C Red No. 34 and its lakes. The analytes are 2-amino-1-naphthalenesulfonic acid (Tobias acid) and 3-hydroxy-2-naphthalenecarboxylic acid (3-hydroxy-2-naphthoic acid). This method can be used for batch certification of the color additives by the U.S. Food and Drug Administration to ensure that each lot meets published specifications for coloring drugs and cosmetics. The new method uses lithium oxalate in methanol-water to dissolve the color additives for analysis. The analytes were identified by comparison of their LC retention times and UV absorption spectra with those of standards. Peak area calibrations were generally linear (R > 0.999) and recoveries were 105% for Tobias acid and 103% for 3-hydroxy-2-naphthoic acid. The limits of determination (LOD) were 0.01% for Tobias acid and 0.03% for 3-hydroxy-2-naphthoic acid. The RSDs at the specification levels were 0.9% for Tobias acid and 3.2% for 3-hydroxy-2-naphthoic acid. Survey analyses of 14 samples of certified D&C Red No. 34 straight colors and lakes from six domestic and foreign manufacturers yielded results for Tobias acid that generally agreed with results previously obtained by using a gravity elution column chromatographic method. Nine of the results for 3-hydroxy-2-naphthoic acid were 2 to 5 times higher than the results obtained using the column chromatographic method. We attribute the lower accuracy of the column chromatographic method to incomplete solubility of the samples using the method conditions and difficulty with interpreting the UV spectrophotometric results.

  5. Relationships between peak ground acceleration, peak ground velocity, and modified mercalli intensity in California

    USGS Publications Warehouse

    Wald, D.J.; Quitoriano, V.; Heaton, T.H.; Kanamori, H.

    1999-01-01

    We have developed regression relationships between Modified Mercalli Intensity (Imm) and peak ground acceleration (PGA) and velocity (PGV) by comparing horizontal peak ground motions to observed intensities for eight significant California earthquakes. For the limited range of Modified Mercalli intensities (Imm), we find that for peak acceleration with V ??? Imm ??? VIII, Imm = 3.66 log(PGA) - 1.66, and for peak velocity with V ??? Imm ??? IX, Imm = 3.47 log(PGV) + 2.35. From comparison with observed intensity maps, we find that a combined regression based on peak velocity for intensity > VII and on peak acceleration for intensity < VII is most suitable for reproducing observed Imm patterns, consistent with high intensities being related to damage (proportional to ground velocity) and with lower intensities determined by felt accounts (most sensitive to higher-frequency ground acceleration). These new Imm relationships are significantly different from the Trifunac and Brady (1975) correlations, which have been used extensively in loss estimation.

  6. Rotating annular chromatograph for continuous metal separations and recovery

    SciTech Connect

    Begovich, J.M.; Sisson, W.G.

    1981-01-01

    Multicomponent liquid chromatographic separations have been achieved by using a slowly rotating annular bed of sorbent material. By continuously introducing the feed material to be separated at a stationary point at the top of the bed and eluent everywhere else around the annulus, elution chromatography occurs. The rotation of the sorbent bed causes the separated components to appear as helical bands, each of which has a characteristic, stationary exit point; hence, the separation process is truly continuous. The concept has been developed primarily on a 279-mm-diam by 0.6-m-long device with a 12.7-mm-wide annulus. The effect of annulus width and diameter has recently been studied using the same device with a 50.8-mm-wide annulus and another 0.6-m-long chromatograph with an 89-mm diameter and annulus widths of 6.4, 12.7, and 22.2 mm. These columns have been constructed of Plexiglas and typically operate at a gauge pressure of 175 kPa. To further study the effect of size and pressure, a new 445-mm-diam by 1-m-long column with a 31.8-mm-wide annulus has been fabricated. Its metal construction allows preparative-scale operation with a wide variety of liquids at pressures to 1.3 MPa. Three metal recovery systems have been explored: (1) separation of iron and aluminum in ammonium sulfate-sulfuric acid solutions; (2) separation of hafnium from zirconium in sulfuric acid solutions; and (3) the separation of copper, nickel, and cobalt in ammonium carbonate solutions. This last system simulates the leach liquor of the Caron process for recovering nickel and cobalt from laterite ores. It has been studied, using similar conditions, on each of the chromatographs, and the results demonstrate the effect of column dimensions on the quality and quantity of the separation. 8 figures, 1 table.

  7. OccuPeak: ChIP-Seq Peak Calling Based on Internal Background Modelling

    PubMed Central

    van den Boogaard, Malou; Christoffels, Vincent M.; Barnett, Phil; Ruijter, Jan M.

    2014-01-01

    ChIP-seq has become a major tool for the genome-wide identification of transcription factor binding or histone modification sites. Most peak-calling algorithms require input control datasets to model the occurrence of background reads to account for local sequencing and GC bias. However, the GC-content of reads in Input-seq datasets deviates significantly from that in ChIP-seq datasets. Moreover, we observed that a commonly used peak calling program performed equally well when the use of a simulated uniform background set was compared to an Input-seq dataset. This contradicts the assumption that input control datasets are necessary to fatefully reflect the background read distribution. Because the GC-content of the abundant single reads in ChIP-seq datasets is similar to those of randomly sampled regions we designed a peak-calling algorithm with a background model based on overlapping single reads. The application, OccuPeak, uses the abundant low frequency tags present in each ChIP-seq dataset to model the background, thereby avoiding the need for additional datasets. Analysis of the performance of OccuPeak showed robust model parameters. Its measure of peak significance, the excess ratio, is only dependent on the tag density of a peak and the global noise levels. Compared to the commonly used peak-calling applications MACS and CisGenome, OccuPeak had the highest sensitivity in an enhancer identification benchmark test, and performed similar in an overlap tests of transcription factor occupation with DNase I hypersensitive sites and H3K27ac sites. Moreover, peaks called by OccuPeak were significantly enriched with cardiac disease-associated SNPs. OccuPeak runs as a standalone application and does not require extensive tweaking of parameters, making its use straightforward and user friendly. Availability: http://occupeak.hfrc.nl PMID:24936875

  8. Convective and Diffusive O2 Transport Components of Peak Oxygen Uptake Following Long-duration Spaceflight

    NASA Technical Reports Server (NTRS)

    Ade, Carl J.; Moore, A. D.

    2014-01-01

    Spaceflight reduces aerobic capacity and may be linked with maladaptations in the O2 transport pathway. The aim was to 1) evaluate the cardiorespiratory adaptations following 6 months aboard the International Space Station and 2) model the contributions of convective (Q (raised dot) O2) and peripheral diffusive (DO2) components of O2 transport to changes in peak O2 uptake (V (raised dot) O2PEAK). To date, 1 male astronaut (XX yrs) completed an incremental exercise test to measure V (raised dot) O2PEAK prior to and 2 days post-flight. Cardiac output (Q (raised dot) ) was measured at three submaximal work rates via carbon dioxide rebreathing. The Q (raised dot) :V (raised dot) O2 relationship was extrapolated to V (raised dot) O2PEAK to determine Q (raised dot) PEAK. Hemoglobin concentration was measured at rest via a venous blood sample. These measurements were used to model the changes in Q (raised dot) O2 and DO2 using Fick's principle of mass conservation and Law of Diffusion as established by Wagner and colleagues (Annu. Rev. Physiol 58: 21-50, 1996 and J. Appl. Physiol. 73: 1067-1076, 1992). V (raised dot) O2PEAK decreased postflight from 3.72 to 3.45 l min-1, but Q (raised dot) PEAK increased from 24.5 to 27.7 l min-1. The decrease in V (raised dot) O2PEAK post-flight was associated with a 21.2% decrease in DO2, an 18.6% decrease in O2 extraction, but a 3.4% increase in Q (raised dot) O2. These preliminary data suggest that long-duration spaceflight reduces peripheral diffusing capacity and that it largely contributes to the post-flight decrease in aerobic capacity.

  9. Liquid chromatographic determination of pyrantel tartrate in medicated formulations.

    PubMed

    Konrardy, Joyce A; Burner, Mary A; Garner, Tommy W; Litchman, Mark A; Webster, Gregory K

    2003-01-01

    The validation of a novel liquid chromatographic (LC) method for the determination of pyrantel tartrate in feed is presented. The method provides a significant improvement over the efficiency and precision of AOAC Official Method 978.30. The method was shown to be accurate, precise, linear, and robust for medicated articles. Unlike the official method, the LC method was shown to be a superior stability-indicating method. After the method was validated by using laboratory blends, the effectiveness of the method was demonstrated with marketed product as well.

  10. Gas chromatographic analysis of trace gas impurities in tungsten hexafluoride.

    PubMed

    Laurens, J B; de Coning, J P; Swinley, J M

    2001-03-09

    Highly reactive fluorinated gaseous matrices require special equipment and techniques for the gas chromatographic analysis of trace impurities in these gases. The impurities that were analysed at the low-microg/l levels included oxygen, nitrogen, carbon dioxide, carbon monoxide, sulfur hexafluoride and hydrogen. This paper describes the use of a system utilising backflush column switching to protect the columns and detectors in the analysis of trace gas impurities in tungsten hexafluoride. Two separate channels were used for the analysis of H2, O2, N2, CO, CO2 and SF6 impurities with pulsed discharge helium ionisation detection.

  11. Preliminary numerical analysis of improved gas chromatograph model

    NASA Technical Reports Server (NTRS)

    Woodrow, P. T.

    1973-01-01

    A mathematical model for the gas chromatograph was developed which incorporates the heretofore neglected transport mechanisms of intraparticle diffusion and rates of adsorption. Because a closed-form analytical solution to the model does not appear realizable, techniques for the numerical solution of the model equations are being investigated. Criteria were developed for using a finite terminal boundary condition in place of an infinite boundary condition used in analytical solution techniques. The class of weighted residual methods known as orthogonal collocation is presently being investigated and appears promising.

  12. Cation exchange chromatographic elution and separation of rubidium

    SciTech Connect

    Mehta, V.P.; Khopkar, S.M.

    1982-01-01

    The systematic cation exchange chromatographic separation of rubidium on Dowex 50W-X8 was carried out with mineral acids and their salts as eluants.A selectivity scale for various eluants in terms of the elution constant was devised. Rubidium was separated from a large number of elements in binary mixtures by the process of gradient or selective elutions or selective sorption. The noteworthy feature of the method is the sequential separation of rubidium from alkali as well as alkaline earth elements.

  13. Correlated peak relative light intensity and peak current in triggered lightning subsequent return strokes

    NASA Technical Reports Server (NTRS)

    Idone, V. P.; Orville, R. E.

    1985-01-01

    The correlation between peak relative light intensity L(R) and stroke peak current I(R) is examined for 39 subsequent return strokes in two triggered lightning flashes. One flash contained 19 strokes and the other 20 strokes for which direct measurements were available of the return stroke peak current at ground. Peak currents ranged from 1.6 to 21 kA. The measurements of peak relative light intensity were obtained from photographic streak recordings using calibrated film and microsecond resolution. Correlations, significant at better than the 0.1 percent level, were found for several functional relationships. Although a relation between L(R) and I(R) is evident in these data, none of the analytical relations considered is clearly favored. The correlation between L(R) and the maximum rate of current rise is also examined, but less correlation than between L(R) and I(R) is found. In addition, the peak relative intensity near ground is evaluated for 22 dart leaders, and a mean ratio of peak dart leader to peak return stroke relative light intensity was found to be 0.1 with a range of 0.02-0.23. Using two different methods, the peak current near ground in these dart leaders is estimated to range from 0.1 to 6 kA.

  14. Peak Wind Tool for General Forecasting

    NASA Technical Reports Server (NTRS)

    Barrett, Joe H., III; Short, David

    2008-01-01

    This report describes work done by the Applied Meteorology Unit (AMU) in predicting peak winds at Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS). The 45th Weather Squadron requested the AMU develop a tool to help them forecast the speed and timing of the daily peak and average wind, from the surface to 300 ft on KSC/CCAFS during the cool season. Based on observations from the KSC/CCAFS wind tower network , Shuttle Landing Facility (SLF) surface observations, and CCAFS sounding s from the cool season months of October 2002 to February 2007, the AMU created mul tiple linear regression equations to predict the timing and speed of the daily peak wind speed, as well as the background average wind speed. Several possible predictors were evaluated, including persistence , the temperature inversion depth and strength, wind speed at the top of the inversion, wind gust factor (ratio of peak wind speed to average wind speed), synoptic weather pattern, occurrence of precipitation at the SLF, and strongest wind in the lowest 3000 ft, 4000 ft, or 5000 ft.

  15. Some Phenomenological Aspects of the Peak Experience

    ERIC Educational Resources Information Center

    Rosenblatt, Howard S.; Bartlett, Iris

    1976-01-01

    This article relates the psychological dynamics of "peak experiences" to two concepts, intentionality and paradoxical intention, within the philosophical orientation of phenomenology. A review of early philosophical theories of self (Kant and Hume) is presented and compared with the experiential emphasis found in the phenomenology of Husserl.…

  16. Avoiding the False Peaks in Correlation Discrimination

    SciTech Connect

    Awwal, A S

    2009-07-31

    Fiducials imprinted on laser beams are used to perform video image based alignment of the 192 laser beams in the National Ignition Facility (NIF) of Lawrence Livermore National Laboratory. In many video images, matched filtering is used to detect the location of these fiducials. Generally, the highest correlation peak is used to determine the position of the fiducials. However, when the signal to-be-detected is very weak compared to the noise, this approach totally breaks down. The highest peaks act as traps for false detection. The active target images used for automatic alignment in the National Ignition Facility are examples of such images. In these images, the fiducials of interest exhibit extremely low intensity and contrast, surrounded by high intensity reflection from metallic objects. Consequently, the highest correlation peaks are caused by these bright objects. In this work, we show how the shape of the correlation is exploited to isolate the valid matches from hundreds of invalid correlation peaks, and therefore identify extremely faint fiducials under very challenging imaging conditions.

  17. On Gaussian feedback capacity

    NASA Technical Reports Server (NTRS)

    Dembo, Amir

    1989-01-01

    Pinsker and Ebert (1970) proved that in channels with additive Gaussian noise, feedback at most doubles the capacity. Cover and Pombra (1989) proved that feedback at most adds half a bit per transmission. Following their approach, the author proves that in the limit as signal power approaches either zero (very low SNR) or infinity (very high SNR), feedback does not increase the finite block-length capacity (which for nonstationary Gaussian channels replaces the standard notion of capacity that may not exist). Tighter upper bounds on the capacity are obtained in the process. Specializing these results to stationary channels, the author recovers some of the bounds recently obtained by Ozarow.

  18. Spanish Peaks, Sangre de Cristo Range, Colorado

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Spanish Peaks, on the eastern flank of the Sangre de Cristo range, abruptly rise 7,000 feet above the western Great Plains. Settlers, treasure hunters, trappers, gold and silver miners have long sighted on these prominent landmarks along the Taos branch of the Santa Fe trail. Well before the westward migration, the mountains figured in the legends and history of the Ute, Apache, Comanche, and earlier tribes. 'Las Cumbres Espanolas' are also mentioned in chronicles of exploration by Spaniards including Ulibarri in 1706 and later by de Anza, who eventually founded San Francisco (California). This exceptional view (STS108-720-32), captured by the crew of Space Shuttle mission STS108, portrays the Spanish Peaks in the context of the southern Rocky Mountains. Uplift of the Sangre de Cristo began about 75 million years ago and produced the long north-trending ridges of faulted and folded rock to the west of the paired peaks. After uplift had ceased (26 to 22 million years ago), the large masses of igneous rock (granite, granodiorite, syenodiorite) that form the Peaks were emplaced (Penn, 1995-2001). East and West Spanish Peaks are 'stocks'-bodies of molten rock that intruded sedimentary layers, cooled and solidified, and were later exposed by erosion. East Peak (E), at 12,708 ft is almost circular and is about 5 1/2 miles long by 3 miles wide, while West Peak (W), at 13,623 ft is roughly 2 3/4 miles long by 1 3/4 miles wide. Great dikes-long stone walls-radiate outward from the mountains like spokes of a wheel, a prominent one forms a broad arc northeast of East Spanish Peak. As the molten rock rose, it forced its way into vertical cracks and joints in the sedimentary strata; the less resistant material was then eroded away, leaving walls of hard rock from 1 foot to 100 feet wide, up to 100 feet high, and as long as 14 miles. Dikes trending almost east-west are also common in the region. For more information visit: Sangres.com: The Spanish Peaks (accessed January 16

  19. Antioxidant capacities and anti-inflammatory effects of flavonoid compounds isolated from acai pulp (Euterpe oleracea Mart.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Acai fruit (Euterpe oleracea Mart.) has been demonstrated to exhibit extremely high antioxidant capacity. Seven major flavonoids were isolated from freeze-dried acai pulp by various chromatographic methods. Their structures were elucidated as orientin (1), homoorientin (2), vitexin (3), luteolin (4)...

  20. Evaluation of Gas Chromatographic Methods for Analysis of Gasoline/Oxygenate Blends.

    DTIC Science & Technology

    1981-12-01

    determination of various oxygenated compounds in gasoline by gas chromotography have been developed.(3-6) These include gas chromatographic (GC) analysis of the...ID-Ai33 0i6 EVALUATION OF GAS CHROMATOGRAPHIC METHODS FOR ANALYSIS i/t OF GASOLINE/OXYGEN.. (U) SOUTHWEST RESEARCH INST SAN ANTONIO TX ARMY FUELS...0 EVALUATION OF GAS -CHROMATOGRAPHIC METHODS FOR ANALYSIS OF GASOLINE/OXYGENATE BLENDS INTERIM REPORT

  1. Mean and peak wind load reduction on heliostats

    NASA Astrophysics Data System (ADS)

    Peterka, J. A.; Tan, L.; Bienkiewcz, B.; Cermak, J. E.

    1987-09-01

    This report presents the results of wind-tunnel tests supported through the Solar Energy Research Institute (SERI) by the Office of Solar Thermal Technology of the U.S. Department of Energy as part of the SERI research effort on innovative concentrators. As gravity loads on drive mechanisms are reduced through stretched-membrane technology, the wind-load contribution of the required drive capacity increases in percentage. Reduction of wind loads can provide economy in support structure and heliostat drive. Wind-tunnel tests have been directed at finding methods to reduce wind loads on heliostats. The tests investigated both mean and peak forces, and moments. A significant increase in ability to predict heliostat wind loads and their reduction within a heliostat field was achieved. In addition, a preliminary review of wind loads on parabolic dish collectors was conducted, resulting in a recommended research program for these type collectors.

  2. Effect of chromatographic conditions on retention behavior and system efficiency for HPTLC of selected psychotropic drugs on chemically bonded stationary phases.

    PubMed

    Petruczynik, Anna; Wróblewski, Karol; Waksmundzka-Hajnos, Monika

    2015-01-01

    Selected psychotropic drug standards have been chromatographed on RP18, CN and diol layers with a variety of aqueous and nonaqueous mobile phases. The effect of buffers at acidic or basic pH, acetic acid, ammonia and diethylamine (DEA) in aqueous mobile phases on retention, efficiency and peak symmetry was examined. Improved peak symmetry and separation selectivity for investigated compounds were observed when ammonia or DEA were used as mobile phase additives. The effect of diethylamine concentration in aqueous eluents on retention, peak symmetry and theoretical plate number obtained on CN plates was also investigated. Because of the strong retention of these basic drugs on stationary phases bonded on silica matrix, nonaqueous eluents containing medium polar diluents, strongly polar modifiers and silanol blockers (ammonia or diethylamine) were applied. Aqueous and nonaqueous eluent systems with the best selectivity and efficiency were used for separate psychotropic drug standards' mixture on CN layer by 2D TLC.

  3. Symptoms, lactate and exercise limitation at peak cycle ergometry in adults with cystic fibrosis.

    PubMed

    Moorcroft, A J; Dodd, M E; Morris, J; Webb, A K

    2005-06-01

    The purpose of this study was to investigate symptoms, lactate accumulation and limiting factors at peak exercise in cystic fibrosis (CF) patients. In total, 104 CF adults attending an adult CF centre and 27 controls performed progressive cycle ergometry to a symptom-limited maximum. Measurements taken at peak exercise included: heart rate, ventilation, oxygen uptake, carbon dioxide output, oxygen saturation and blood lactate. Symptom scores of perceived breathlessness and muscle effort were recorded using Borg scales. The CF subjects had a lower mean body mass index, forced expiratory volume in one second (FEV(1)) and peak oxygen uptake than controls. Peak lactate concentrations were very similar to controls (mean+/-sd 6.8+/-2.0 mmol x L(-1) versus 7.4+/-1.0 mmol x L(-1)). Symptom scores were no different to controls for either breathlessness (4.5+/-2.0 versus 4.3+/-1.0) or perceived muscle effort (6.1+/-2.0 versus 6.5+/-1.0), with higher scores for muscle effort than breathlessness in both groups. In addition, peak ventilation was lower than the predicted maximum, and high peak heart rates were recorded supporting nonpulmonary factors as important in limiting peak exercise. Peak oxygen uptake was correlated with FEV(1). Comparison of CF subjects with mild or moderate pulmonary disease and controls revealed similar exercise responses. In contrast, those CF patients with severe lung disease (FEV(1) <40% predicted) had significantly higher breathlessness, lower muscle effort scores, lower peak lactate, lower peak heart rate and a mean ventilation exceeding predicted, thus confirming that ventilation was the major factor limiting exercise. In conclusion, cystic fibrosis subjects have a reduced peak exercise capacity, but their exercise response is similar to controls in generating high blood-lactate concentrations and symptoms of muscle effort in excess of dyspnoea. Nonpulmonary factors influence peak performance more in those without severe disease.

  4. Performance characteristics of an ion chromatographic method for the quantitation of citrate and phosphate in pharmaceutical solutions.

    PubMed

    Jenke, Dennis; Sadain, Salma; Nunez, Karen; Byrne, Frances

    2007-01-01

    The performance of an ion chromatographic method for measuring citrate and phosphate in pharmaceutical solutions is evaluated. Performance characteristics examined include accuracy, precision, specificity, response linearity, robustness, and the ability to meet system suitability criteria. In general, the method is found to be robust within reasonable deviations from its specified operating conditions. Analytical accuracy is typically 100 +/- 3%, and short-term precision is not more than 1.5% relative standard deviation. The instrument response is linear over a range of 50% to 150% of the standard preparation target concentrations (12 mg/L for phosphate and 20 mg/L for citrate), and the results obtained using a single-point standard versus a calibration curve are essentially equivalent. A small analytical bias is observed and ascribed to the relative purity of the differing salts, used as raw materials in tested finished products and as reference standards in the analytical method. The assay is specific in that no phosphate or citrate peaks are observed in a variety of method-related solutions and matrix blanks (with and without autoclaving). The assay with manual preparation of the eluents is sensitive to the composition of the eluent in the sense that the eluent must be effectively degassed and protected from CO(2) ingress during use. In order for the assay to perform effectively, extensive system equilibration and conditioning is required. However, a properly conditioned and equilibrated system can be used to test a number of samples via chromatographic runs that include many (> 50) injections.

  5. Gas chromatographic-mass spectrometric determination of brain levels of alpha-cholest-8-en-3beta-ol (lathosterol).

    PubMed

    Luzón-Toro, Berta; Zafra-Gómez, Alberto; Ballesteros, Oscar

    2007-05-01

    A gas chromatographic-mass spectrometric (GC-MS) method is proposed for the detection and quantification of lathosterol in rabbit brain. This compound is one of the most important precursors of the cholesterol synthesis. The interest in brain cholesterol metabolism is growing nowadays since it was described to play an important role in some neurodegenerative disorders such as Alzheimer's disease and Multiple Sclerosis. The analytical methodology proposed involves a liquid-liquid extraction procedure (LLE) followed by a silylation step previous to the GC-MS analysis. The chromatographic separation was performed by using a low bleed HP5-MS fused silica capillary column. A clean up is not necessary when using single-ion monitoring (SIM) mode. The molecular ion appears at 458 m/z; being as well the base peak. Alpha-naphtol was used as an internal standard. The detection limit obtained was 0.09 microg mL(-1). The method was applied to the determination of brain lathosterol levels in rabbits fed with different types of diets (control and atherogenic, supplemented or not with natural polyphenolic antioxidants). The quantification of the compound in samples showed a reduction, after 1 month, of this precursor of cholesterol synthesis in groups fed with antioxidant supplemented diets.

  6. Heat Capacity Analysis Report

    SciTech Connect

    A. Findikakis

    2004-11-01

    The purpose of this report is to provide heat capacity values for the host and surrounding rock layers for the waste repository at Yucca Mountain. The heat capacity representations provided by this analysis are used in unsaturated zone (UZ) flow, transport, and coupled processes numerical modeling activities, and in thermal analyses as part of the design of the repository to support the license application. Among the reports that use the heat capacity values estimated in this report are the ''Multiscale Thermohydrologic Model'' report, the ''Drift Degradation Analysis'' report, the ''Ventilation Model and Analysis Report, the Igneous Intrusion Impacts on Waste Packages and Waste Forms'' report, the ''Dike/Drift Interactions report, the Drift-Scale Coupled Processes (DST and TH Seepage) Models'' report, and the ''In-Drift Natural Convection and Condensation'' report. The specific objective of this study is to determine the rock-grain and rock-mass heat capacities for the geologic stratigraphy identified in the ''Mineralogic Model (MM3.0) Report'' (BSC 2004 [DIRS 170031], Table 1-1). This report provides estimates of the heat capacity for all stratigraphic layers except the Paleozoic, for which the mineralogic abundance data required to estimate the heat capacity are not available. The temperature range of interest in this analysis is 25 C to 325 C. This interval is broken into three separate temperature sub-intervals: 25 C to 95 C, 95 C to 114 C, and 114 C to 325 C, which correspond to the preboiling, trans-boiling, and postboiling regimes. Heat capacity is defined as the amount of energy required to raise the temperature of a unit mass of material by one degree (Nimick and Connolly 1991 [DIRS 100690], p. 5). The rock-grain heat capacity is defined as the heat capacity of the rock solids (minerals), and does not include the effect of water that exists in the rock pores. By comparison, the rock-mass heat capacity considers the heat capacity of both solids and pore

  7. Multi-objective optimization of chromatographic rare earth element separation.

    PubMed

    Knutson, Hans-Kristian; Holmqvist, Anders; Nilsson, Bernt

    2015-10-16

    The importance of rare earth elements in modern technological industry grows, and as a result the interest for developing separation processes increases. This work is a part of developing chromatography as a rare earth element processing method. Process optimization is an important step in process development, and there are several competing objectives that need to be considered in a chromatographic separation process. Most studies are limited to evaluating the two competing objectives productivity and yield, and studies of scenarios with tri-objective optimizations are scarce. Tri-objective optimizations are much needed when evaluating the chromatographic separation of rare earth elements due to the importance of product pool concentration along with productivity and yield as process objectives. In this work, a multi-objective optimization strategy considering productivity, yield and pool concentration is proposed. This was carried out in the frame of a model based optimization study on a batch chromatography separation of the rare earth elements samarium, europium and gadolinium. The findings from the multi-objective optimization were used to provide with a general strategy for achieving desirable operation points, resulting in a productivity ranging between 0.61 and 0.75 kgEu/mcolumn(3), h(-1) and a pool concentration between 0.52 and 0.79 kgEu/m(3), while maintaining a purity above 99% and never falling below an 80% yield for the main target component europium.

  8. Gas chromatographic retention characteristics of phenols with Superox-20M

    SciTech Connect

    White, C.M.; Li, N.C.

    1982-08-01

    The gas chromatographic retention characteristics of a variety of underivatized phenols have been studied by using Superox-20M coated on fused silica. The relative retention times of thes compounds were measured at 160, 150, and 140/sup 0/C in order to determine the effect of operating temperature on relative retention. This information is used to predict relative retention times of phenols for which we had no standards. The linear temperature-programmed retention indexes of the solutes were measured. The retention of phenols on this phase is a function of the compounds vapor pressure, its ability to hydrogen bond with the stationary phase, and the strengths of those hydrogen bonds. These properties are in turn governed by steric, inductive, and resonance effects of the substituents. Linear free-energy relations between the logarithm of the ratio of the activity coefficients of phenol to substituted phenol (calculated from relative retention data) and the chromatographic substituent constant, sigma/sub c/, have been determined for some phenols on Superox-20M. Lastly, it was shown by nuclear magnetic resonance experiments that Superox-20M is apparently a poly(ethylene glycol) (also called a polyoxiran or poly(ethylene oxide)). 5 figures, 3 tables.

  9. Thin layer chromatographic determination of deoxynivalenol in processed grain products.

    PubMed

    Trucksess, M W; Flood, M T; Page, S W

    1986-01-01

    The thin layer chromatographic (TLC) method of Trucksess et al. (J. Assoc. Off. Anal. Chem. (1984) 67, 40-43) was modified for the determination of deoxynivalenol (DON) in high-sugar breakfast cereals, corn syrup, and beer. Celite was added to the substrate before extraction with acetonitrile-water (84 + 16). After filtration through an alumina-charcoal-Celite (0.5 + 0.7 + 0.3) column, the filtrate was evaporated to dryness and redissolved in water, which was passed through an octylsilyl reverse phase column. DON was eluted with anhydrous ethyl ether. The residue remaining after the eluate was evaporated to dryness was dissolved in CHCl3-acetonitrile (4 + 1) and chromatographed on AlCl3-impregnated silica gel TLC plates. The blue fluorescent DON spot was quantitated fluorodensitometrically after the TLC plate was heated at 120 degrees C for 7 min. Recoveries of DON added to breakfast cereals at 100, 200, and 400 ng/g levels and to syrup and beer at 50, 100, and 200 ng/g levels averaged 86%. The limit of determination in these products was about 50 ng/g.

  10. Effect of reservoir storage on peak flow

    USGS Publications Warehouse

    Mitchell, William D.

    1962-01-01

    For observation of small-basin flood peaks, numerous crest-stage gages now are operated at culverts in roadway embankments. To the extent that they obstruct the natural flood plains of the streams, these embankments serve to create detention reservoirs, and thus to reduce the magnitude of observed peak flows. Hence, it is desirable to obtain a factor, I/O, by which the observed outflow peaks may be adjusted to corresponding inflow peaks. The problem is made more difficult by the fact that, at most of these observation sites, only peak stages and discharges are observed, and complete hydrographs are not available. It is postulated that the inflow hydrographs may be described in terms of Q, the instantaneous discharge; A, the size of drainage area; Pe, the amount of rainfall excess; H, the time from beginning of rainfall excess; D, the duration of rainfall excess; and T and k, characteristic times for the drainage area, and indicative of the time lag between rainfall and runoff. These factors are combined into the dimensionless ratios (QT/APe), (H/T), (k/T), and (D/T), leading to families of inflow hydrographs in which the first ratio is the ordinate, the second is the abscissa, and the third and fourth are distinguishing parameters. Sixteen dimensionless inflow hydrographs have been routed through reservoir storage to obtain 139 corresponding outflow hydrographs. In most of the routings it has been assumed that the storage-outflow relation is linear; that is, that storage is some constant, K, times the outflow. The existence of nonlinear storage is recognized, and exploratory nonlinear routings are described, but analyses and conclusions are confined to the problems of linear storage. Comparisons between inflow hydrographs and outflow hydrographs indicate that, at least for linear storage, I/O=f(k/T, D/T, K/T) in which I and O are, respectively, the magnitudes of the inflow and the outflow peaks, and T, k, D, and K are as defined above. Diagrams are presented to

  11. Problems of Excess Capacity

    NASA Technical Reports Server (NTRS)

    Douglas, G.

    1972-01-01

    The problems of excess capacity in the airline industry are discussed with focus on the following topics: load factors; fair rate of return on investment; service-quality rivalry among airlines; pricing (fare) policies; aircraft production; and the impacts of excess capacity on operating costs. Also included is a discussion of the interrelationships among these topics.

  12. Liquid heat capacity lasers

    DOEpatents

    Comaskey, Brian J.; Scheibner, Karl F.; Ault, Earl R.

    2007-05-01

    The heat capacity laser concept is extended to systems in which the heat capacity lasing media is a liquid. The laser active liquid is circulated from a reservoir (where the bulk of the media and hence waste heat resides) through a channel so configured for both optical pumping of the media for gain and for light amplification from the resulting gain.

  13. Contributions of Astronauts Aerobic Exercise Intensity and Time on Change in VO2peak during Spaceflight

    NASA Technical Reports Server (NTRS)

    Downs, Meghan E.; Buxton, Roxanne; Moore, Alan; Ploutz-Snyder, Robert; Ploutz-Snyder, Lori

    2014-01-01

    There is considerable variability among astronauts with respect to changes in maximal aerobic capacity (VO2peak) during International Space Station (ISS) missions, ranging from a 5% increase to 30% decline. Individual differences may be due to in-flight aerobic exercise time and intensity. PURPOSE: To evaluate the effects of in-flight aerobic exercise time and intensity on change in VO2peak during ISS missions. METHODS: Astronauts (N=11) performed peak cycle tests approx 60 days before flight (L-60), on flight day (FD) approx 14, and every approx 30 days thereafter. Metabolic gas analysis and heart rate (HR) were measured continuously during the test using the portable pulmonary function system. HR and duration of each in-flight cycle ergometer and treadmill (TM) session were recorded and averaged in time segments corresponding to each peak test. Mixed effects linear regression with exercise mode (TM or cycle) as a categorical variable was used to assess the contributions of exercise intensity (%time >70% peak HR or %time >90% peak HR) and time (min/wk), adjusted for body weight, on %change in VO2peak during the mission, and incorporating the repeated-measures experimental design. RESULTS: 110 observations were included in the model (4-6 peak cycle tests per astronaut, 2 exercise devices). VO2peak was reduced from preflight throughout the mission (FD14: 13+/-13% and FD 105: 8+/-10%). Exercise intensity (%peak HR: FD14=66+/-14; FD105=75+/-8) and time (min/wk: FD14=82+/-46; FD105=158+/-40) increased during flight. The models showed main effects for exercise time and intensity with no interactions between time, intensity, and device (70% peak HR: time [z-score=2.39; P=0.017], intensity [z-score=3.51; P=0.000]; 90% peak HR: time [zscore= 3.31; P=0.001], intensity [z-score=2.24; P=0.025]). CONCLUSION: Exercise time and intensity independently contribute to %change in VO2peak during ISS missions, indicating that there are minimal values for exercise time and intensity

  14. A simple high-performance liquid chromatographic assay for ciprofloxacin in human serum.

    PubMed

    Jim, L K; el-Sayed, N; al-Khamis, K I

    1992-04-01

    A simple and selective high-performance liquid chromatographic (HPLC) method for the determination of ciprofloxacin in serum has been developed and evaluated. Serum protein was precipitated with acetonitrile. The drug and the internal standard (quinine) were evaluated from a 10 microns U-Bondapack C-18 cartridge at ambient temperature with a mobile phase consisting of acetonitrile: 0.1 M sodium dihydrogen phosphate (20:80%, v/v) adjusted to pH 3.9 with phosphoric acid, and at a flow rate of 2.5 ml/min. The effluent was monitored on a fluorescence detector using an excitation and emission wavelength of 280 and 455 nm, respectively. Each analysis required no longer than 6 min. Quantification was achieved by the measurement of the peak-height ratio and the limit of quantification for ciprofloxacin in serum is 25 ng/ml. The intraday coefficient of variation (CV) ranged from 0.4 to 5.8%, and interday CV from 4.6 to 8.8% at three different concentrations. Relative recovery ranged from 98 to 100.2% at three different concentrations. Preliminary stability tests show that ciprofloxacin is stable for at least 3 weeks in serum after freezing.

  15. Improved high-performance liquid chromatographic method for the determination of coenzyme Q10 in plasma.

    PubMed

    Grossi, G; Bargossi, A M; Fiorella, P L; Piazzi, S; Battino, M; Bianchi, G P

    1992-02-28

    Coenzyme (Co) Q10 was dissociated from lipoproteins in plasma by treatment with methanol and extraction with n-hexane. Subsequent clean-up on silica gel and C18 solid-phase extraction cartridges with complete recovery (99 +/- 1.2%) produced a clean extract. High-performance liquid chromatographic (HPLC) separation was performed on a C18 reversed-phase column. Three simple, rapid procedures are presented: HPLC with final UV (275 nm) detection, a microanalysis utilizing a three-electrode electrochemical detector and a microanalysis with column-switching HPLC and electrochemical detection. The methods correlate very well with classical ethanol-n-hexane extraction with UV detection. The identity and purity of the Co Q10 peak were investigated and the resulting methods were concluded to be suitable for total plasma Co Q10 determination. The average level in healthy subjects was 0.80 +/- 0.20 mg/l; the minimum detectable Co Q10 plasma level was 0.05 and 0.005 mg/l for UV and electrochemical detection, respectively. The methods were applied to many samples and the plasma Co Q10 reference values for healthy subjects, athletes, hyperthyroid, hypothyroid and hypercholesterolaemic patients are given.

  16. High performance liquid chromatographic determination of etofibrate and its hydrolysis products.

    PubMed

    el-Gindy, Alaa; Hadad, Ghada M; Mahmoud, Waleed M M

    2007-01-04

    High performance liquid chromatographic (HPLC) method is presented for the determination of etofibrate (EF) and its hydrolysis products. The method was based on HPLC separation of EF from its hydrolysis products using cyanopropyl column at ambient temperature with mobile phase consisting of acetonitrile-10 mM potassium dihydrogen phosphate, pH was adjusted to 4.1 using phosphoric acid (50:50, v/v). Quantitation was achieved with UV detection at 221 nm based on peak area. The flow rate was 1.5 ml min(-1). The proposed method was used to investigate the kinetics of acidic hydrolysis process of EF at different temperatures and the apparent pseudo first-order rate constant, half-life and activation energy were calculated. The kinetics of alkaline hydrolysis process of EF using 0.01 M sodium hydroxide at different temperatures cannot be studied as the drug is rapidly hydrolyzed in alkaline medium. The pH-rate profile of hydrolysis of EF in Britton-Robinson buffer solutions within the pH range 2-10 were studied.

  17. Gas chromatographic and mass spectrometric analysis of polychlorinated biphenyls in human placenta and cord blood

    SciTech Connect

    Ando, M.; Saito, H.; Wakisaka, I.

    1986-10-01

    Gas chromatographic and mass spectrometric analyses of polychlorinated biphenyls (PCBs) in placenta, maternal blood, cord blood, and milk were carried out. Trichlorobiphenyl, tetrachlorobiphenyl, pentachlorobiphenyls, and hexachlorobiphenyls were identified by the mass chromatogram and the mass spectra. Some minor peaks of PCBs were identified by gas chromatography. The relationship between the PCB concentration in placenta and that in milk is different in each PCB congener. The higher the chlorine content of the PCB congener, the more significant the correlation. No significant but a low negative correlation exists between the concentration of some PCB congeners in the placenta and that in cord blood. On the other hand, a significant linear correlation exists between the concentration of hexachlorobenzene in the placenta and that in cord blood. The transplacental transport of each PCB congener varied depending upon its chemical nature. Trichlorobiphenyl and tetrachlorobiphenyl were more transferable than hexachlorobiphenyls. The results show that the placenta and cord blood are useful human samples to analyze the body burden of environmental pollutants and to estimate their transfer from mother to fetus.

  18. Brain penetration of colistin in mice assessed by a novel high-performance liquid chromatographic technique.

    PubMed

    Jin, Liang; Li, Jian; Nation, Roger L; Nicolazzo, Joseph A

    2009-10-01

    A sensitive and reliable liquid chromatographic method was developed and validated for the determination of colistin concentrations in mouse brain homogenate. With a mobile phase consisting of acetonitrile-tetrahydrofuran-water (50:25:25 [vol/vol]) at a flow rate of 1 ml/min, a linear correlation between peak area and colistin concentration was observed over the concentration range of 93.8 to 3,000 ng/g in brain tissue (R2 > 0.994). Intra- and interday coefficients of variation were 5.1 to 8.3% and 5.8 to 8.5%, respectively, and the recovery ranged from 85% to 94%. This assay was then utilized to determine the amount of colistin that permeated the blood-brain barrier over a 2-h period following bolus intravenous administration of colistin sulfate to mice. After a single dose of 5 mg/kg of body weight to mice, brain homogenate concentrations of colistin were very low, relative to plasma colistin concentrations, suggesting that colistin permeability across the healthy blood-brain barrier is negligible during this experimental period.

  19. Multivariate Chemometrics with Regression and Classification Analyses in Heroin Profiling Based on the Chromatographic Data.

    PubMed

    B Gadžurić, Slobodan; O Podunavac Kuzmanović, Sanja; B Vraneš, Milan; Petrin, Marija; Bugarski, Tatjana; Kovačević, Strahinja Z

    2016-01-01

    The purpose of this work is to promote and facilitate forensic profiling and chemical analysis of illicit drug samples in order to determine their origin, methods of production and transfer through the country. The article is based on the gas chromatography analysis of heroin samples seized from three different locations in Serbia. Chemometric approach with appropriate statistical tools (multiple-linear regression (MLR), hierarchical cluster analysis (HCA) and Wald-Wolfowitz run (WWR) test) were applied on chromatographic data of heroin samples in order to correlate and examine the geographic origin of seized heroin samples. The best MLR models were further validated by leave-one-out technique as well as by the calculation of basic statistical parameters for the established models. To confirm the predictive power of the models, external set of heroin samples was used. High agreement between experimental and predicted values of acetyl thebaol and diacetyl morphine peak ratio, obtained in the validation procedure, indicated the good quality of derived MLR models. WWR test showed which examined heroin samples come from the same population, and HCA was applied in order to overview the similarities among the studied heroine samples.

  20. Enantioseparation of cetirizine by chromatographic methods and discrimination by 1H-NMR.

    PubMed

    Taha, Elham A; Salama, Nahla N; Wang, Shudong

    2009-03-01

    Cetirizine is an antihistaminic drug used to prevent and treat allergic conditions. It is currently marketed as a racemate. The H1-antagonist activity of cetirizine is primarily due to (R)-levocetirizine. This has led to the introduction of (R)-levocetirizine into clinical practice, and the chiral switching is expected to be more selective and safer. The present work represents three methods for the analysis and chiral discrimination of cetirizine. The first method was based on the enantioseparation of cetirizine on silica gel TLC plates using different chiral selectors as mobile phase additives. The mobile phase enabling successful resolution was acetonitrile-water 17: 3, (v/v) containing 1 mM of chiral selector, namely hydroxypropyl-beta-cyclodextrin, chondroitin sulphate or vancomycin hydrochloride. The second method was a validated high performance liquid chromatography (HPLC), based on stereoselective separation of cetirizine and quantitative determination of its eutomer (R)-levocetirizine on a monolithic C18 column using hydroxypropyl-beta-cyclodextrin as a chiral mobile phase additive. The resolved peaks of (R)-levocetirizine and (S)-dextrocetirizine were confirmed by further mass spectrometry. The third method used a (1)H-NMR technique to characterize cetirizine and (R)-levocetirizine. These methods are selective and accurate, and can be easily applied for chiral discrimination and determination of cetirizine in drug substance and drug product in quality control laboratory. Moreover, chiral purity testing of (R)-levocetirizine can also be monitored by the chromatographic methods.

  1. Liquid chromatographic determination of oxytetracycline in edible fish fillets from six species of fish

    USGS Publications Warehouse

    Meinertz, J.R.; Stehly, G.R.; Gingerich, W.H.

    1998-01-01

    The approved use of oxytetracycline (OTC) in U.S. Aquaculture is limited to specific diseases in salmonids and channel catfish. OTC may also be effective in controlling diseases in other fish species important to public aquaculture, but before approved use of OTC can be augmented, an analytical method for determining OTC in fillet tissue from multiple species of fish will be required to support residue depletion studies. The objective of this study was to develop and validate a liquid chromatographic (LC) method that is accurate, precise, and sensitive for OTC in edible fillets from multiple species of fish. Homogenized fillet tissues from walleye, Atlantic salmon, striped bass, white sturgeon, rainbow trout, and channel catfish were fortified with OTC at nominal concentrations of 10, 20, 100, 1000, and 5000 ng/g. In tissues fortified with OTC at 100, 1000, and 5000 ng/g, mean recoveries ranged from 83 to 90%, and relative standard deviations (RSDs) ranged from 0.9 to 5.8%. In all other tissues, mean recoveries ranged from 59 to 98%, and RSDs ranged from 3.3 to 20%. Method quantitation limits ranged from 6 to 22 ng/g for the 6 species. The LC parameters produced easily integratable OTC peaks without coelution of endogenous compounds. The method is accurate, precise, and sensitive for OTC in fillet tissue from 6 species of fish from 5 phylogenetically diverse groups.

  2. Multivariate Chemometrics with Regression and Classification Analyses in Heroin Profiling Based on the Chromatographic Data

    PubMed Central

    B. Gadžurić, Slobodan; O. Podunavac Kuzmanović, Sanja; B. Vraneš, Milan; Petrin, Marija; Bugarski, Tatjana; Kovačević, Strahinja Z.

    2016-01-01

    The purpose of this work is to promote and facilitate forensic profiling and chemical analysis of illicit drug samples in order to determine their origin, methods of production and transfer through the country. The article is based on the gas chromatography analysis of heroin samples seized from three different locations in Serbia. Chemometric approach with appropriate statistical tools (multiple-linear regression (MLR), hierarchical cluster analysis (HCA) and Wald-Wolfowitz run (WWR) test) were applied on chromatographic data of heroin samples in order to correlate and examine the geographic origin of seized heroin samples. The best MLR models were further validated by leave-one-out technique as well as by the calculation of basic statistical parameters for the established models. To confirm the predictive power of the models, external set of heroin samples was used. High agreement between experimental and predicted values of acetyl thebaol and diacetyl morphine peak ratio, obtained in the validation procedure, indicated the good quality of derived MLR models. WWR test showed which examined heroin samples come from the same population, and HCA was applied in order to overview the similarities among the studied heroine samples. PMID:28243268

  3. Control of propranolol intake by direct chromatographic detection of alpha-naphthoxylactic acid in urine.

    PubMed

    Ruiz-Angel, M J; Fernández-López, P; Murillo-Pulgarín, J A; García-Alvarez-Coque, M C

    2002-02-15

    A rapid chromatographic procedure with a C18 column, a mobile phase of 0.15 M sodium dodecyl sulfate (SDS)-10% (v/v) 1-propanol at pH 3 (0.01 M phosphate buffer), and fluorimetric detection, is reported for the control of propranolol (PPL) intake in urine samples, which are injected directly without any other treatment than filtration. The peak of PPL was only observed in samples taken a few hours after ingestion of the drug due to its extensive conjugation and metabolisation. The detection of several unconjugated PPL metabolites was therefore considered: desisopropylpropranolol (DIP), propranolol glycol (PPG), alpha-naphthoxylactic acid (NLT) and alpha-naphthoxyacetic acid (NAC). NLT showed the best characteristics: it eluted at a much shorter retention time than PPL, its concentration in urine samples was greater and it did not present any interference from endogeneous compounds in urine, common drugs or drugs administered in combination with PPL. The limit of quantification, measured as the concentration of analyte providing a relative standard deviation of 20%, was 24 ng/ml, and the day-to-day imprecision was below 4% for concentrations above 200 ng/ml. The procedure allows the routine control of PPL at therapeutic urine levels. Urinary excretion studies showed that the detection of NLT is possible at least up to 20-30 h after oral administration.

  4. Effects of muscle electrical stimulation on peak VO2 in cardiac transplant patients.

    PubMed

    Vaquero, A F; Chicharro, J L; Gil, L; Ruiz, M P; Sánchez, V; Lucía, A; Urrea, S; Gómez, M A

    1998-07-01

    Peak oxygen consumption (peak VO2) has become a critical component in the evaluation of heart transplant recipients (HTR). In these patients, peak VO2 remains low after cardiac transplantation mainly because of persisting peripheral limitations in the working muscles. Muscular electrical stimulation, on the other hand, has been shown to enhance the oxidative capacity of healthy muscle. It was the purpose of our investigation to study the effects of ES on the peak VO2 of HTR. Fourteen (11 males and 3 females) HTR (age: 57+/-7yr, mean +/- SD; height: 163+/-7 cm, weight: 70.5+/-8.6 kg) were selected as subjects and each of them was randomly assigned to one of two groups: (a) group EXP (n = 7), receiving electrical stimulation on both quadriceps muscles during a period of 8 weeks, and (b) group CONT (n = 7), not receiving electrical stimulation. Before (PRE) and after (POST) the aforementioned 8-week period, respectively, all the subjects performed a cardiopulmonary exercise test (ramp protocol) on a cycle ergometer for peak VO2 determination. PRE values of peak VO2 were similar in both groups (17.1+/-2.0 vs 16.9+/-3.8ml x kg(-1) x min(-1) in EXP and CONT, respectively). However, peak values of VO2 significantly increased in EXP (p < 0.05) after the period of electrical stimulation (POST peak VO2: 18.7+/-2.0ml x kg(-1)), whereas no change was observed in CONT (POST peak VO2: 16.2+/-3.2 ml x kg(-1) x min(-1)). In conclusion, electrical stimulation could therefore be used to improve the functional capacity of HTR, and might be included in the rehabilitation programs of this population group.

  5. Nanofluid heat capacities

    NASA Astrophysics Data System (ADS)

    Starace, Anne K.; Gomez, Judith C.; Wang, Jun; Pradhan, Sulolit; Glatzmaier, Greg C.

    2011-12-01

    Significant increases in the heat capacity of heat transfer fluids are needed not only to reduce the costs of liquid heating and cooling processes, but also to bring clean energy producing technologies like concentrating solar power (CSP) to price parity with conventional energy generation. It has been postulated that nanofluids could have higher heat capacities than conventional fluids. In this work, nano- and micron-sized particles were added to five base fluids (poly-α olefin, mineral oil, ethylene glycol, a mixture of water and ethylene glycol, and calcium nitrate tetrahydrate), and the resulting heat capacities were measured and compared with those of the neat base fluids and the weighted average of the heat capacities of the components. The particles used were inert metals and metal oxides that did not undergo any phase transitions over the temperature range studied. In the nanofluids studied here, we found no increase in heat capacity upon the addition of the particles larger than the experimental error.

  6. Who needs capacity?

    PubMed

    Buchanan, Alec

    2015-01-01

    The UK Law Commission's Discussion Paper, Criminal Liability: Insanity and Automatism, recommends introducing the concept of capacity to the insanity defence. The concept of capacity has an established role in those parts of the law that concern the validity of the decisions that people make, for instance in composing a will or entering into a contract. Making mental capacity a criterion for criminal responsibility in a mentally disordered defendant, however, is potentially problematic. First, the term capacity already has several different meanings in the literature on the jurisprudence of mental abnormality. Second, using the concept of capacity in the way that the Law Commission proposes poses difficulties that relate to the provision of testimony by expert witnesses.

  7. Lumped parameter model for prediction of initial breakthrough profiles for the chromatographic capture of antibodies from a complex feedstock.

    PubMed

    Bak, Hanne; Thomas, Owen R T; Abildskov, Jens

    2007-03-15

    A simple mathematical model to predict initial breakthrough profiles from preparative chromatographic separations of biological macromolecules has been developed. A lumped parameter approach was applied, employing Langmuirian adsorption kinetics to describe the rate of mass transfer (MT) from the bulk liquid in the column to the bound state. Equilibrium and kinetic adsorption data were determined for six different packed bed chromatographic adsorbents: two derivatised with rProtein A; and four functionalised with synthetic low molecular weight ligands. All adsorption isotherms were well described by the Langmuir model, whereas the data fitting to kinetic batch experiments showed that the model was inadequate after the first approximately 25 min of adsorption for four of the six adsorbents. The model underestimated the dynamic Ig breakthough on packed beds of rProtein A Sepharose FF, MabSelect, MBI HyperCel, and MabSorbent A1P, applying a feedstock of 20-100% (v/v) clarified rabbit antiserum. However, when employing a maximum adsorption capacity 25% greater than that determined in batch binding studies, excellent agreement was obtained at all antiserum strengths for most adsorbents. Useful insights into scale-up and process design can be obtained by applying the model, without determining tentative parameters specific for each adsorbent and target protein concentration. However, the model parameters are solvent dependent so a prerequisite for its true applicability is that binding is both Langmuirian and essentially independent of the ionic strength of the feedstock applied.

  8. Effect of gear ratio on peak power and time to peak power in BMX cyclists.

    PubMed

    Rylands, Lee P; Roberts, Simon J; Hurst, Howard T

    2017-03-01

    The aim of this study was to ascertain if gear ratio selection would have an effect on peak power and time to peak power production in elite Bicycle Motocross (BMX) cyclists. Eight male elite BMX riders volunteered for the study. Each rider performed three, 10-s maximal sprints on an Olympic standard indoor BMX track. The riders' bicycles were fitted with a portable SRM power meter. Each rider performed the three sprints using gear ratios of 41/16, 43/16 and 45/16 tooth. The results from the 41/16 and 45/16 gear ratios were compared to the current standard 43/16 gear ratio. Statistically, significant differences were found between the gear ratios for peak power (F(2,14) = 6.448; p = .010) and peak torque (F(2,14) = 4.777; p = .026), but no significant difference was found for time to peak power (F(2,14) = 0.200; p = .821). When comparing gear ratios, the results showed a 45/16 gear ratio elicited the highest peak power,1658 ± 221 W, compared to 1436 ± 129 W and 1380 ± 56 W, for the 43/16 and 41/16 ratios, respectively. The time to peak power showed a 41/16 tooth gear ratio attained peak power in -0.01 s and a 45/16 in 0.22 s compared to the 43/16. The findings of this study suggest that gear ratio choice has a significant effect on peak power production, though time to peak power output is not significantly affected. Therefore, selecting a higher gear ratio results in riders attaining higher power outputs without reducing their start time.

  9. Sample preparation and high-performance liquid chromatographic analysis of deoxyribonucleoside triphosphates in individual rat embryos.

    PubMed

    Mole, M L; Hunter, D L; Gao, P; Lau, C

    1998-06-01

    A rapid, robust, and sensitive method has been developed to measure concentrations of deoxyribonucleoside triphosphates in individual, day 14 rat embryos by modifying and optimizing existing methods for cellular extracts. Significant changes include: (i) oxidative degradation of ribonucleoside triphosphates using methylamine at lower pH (decreased from 6.5 to 4.0) to improve poor HPLC peak shape of early eluting nucleotides; (ii) glass fiber disc solid-phase extraction of the reaction mixture, which dramatically reduces impurities that interfere with nucleotide measurement, eliminates the necessity of column regeneration, and allows mobile phase recycling; and (iii) lower ionic strength (reduced from 0.4 to 0.26 or 0.12 M ammonium phosphate) and higher pH (increased from 3.25 to 5.55 or 6.98, respectively) mobile phase, conditions which are less destructive to the column's bonded phase and silica support, thereby contributing to longer column life. Enhancements include: (i) filtration of the sample prior to HPLC injection and addition of an in-line filter, guard column, and saturating precolumn of silica in the mobile phase flow, which aids substantially in extending column life and improves chromatographic stability, and (ii) inclusion of an internal standard to correct for mechanical losses. Limits of determination at a signal to noise ratio of 6:1 range from 5.5 to 12 pmol on-column or 0.41 to 0.87 pmol/mg of embryonic tissue depending on the specific nucleotide. Recoveries are quantitative for all nucleotides, and interassay variabilities are between 5 and 7% when quantified by peak height. The method has also been applied successfully to analysis of murine erythroleukemic cell cultures and this, when coupled with the embryo results, suggests its general utility.

  10. Status of the Frisco Peak Observatory

    NASA Astrophysics Data System (ADS)

    Ricketts, Paul; Springer, Wayne; Dawson, Kyle; Kieda, Dave; Gondolo, Paolo; Bolton, Adam

    2009-10-01

    The University of Utah has constructed an astronomical observatory located at an elevation of approximately 9600 feet of Frisco Peak west of Milford, Utah. This site was chosen after performing a survey of potential observatory sites throughout Southern Utah. At the time of writing this abstract, the dome and control buildings have been completed. Installation of a 32'' telescope manufactured by DFM Engineering is scheduled to start October 5, 2009. Commissioning of the telescope will take place this fall. A study of the photometric quality of the observatory site will be performed as well. A description of the observatory site survey and the construction and commissioning of the Frisco Peak Observatory will be presented.

  11. Peak oil, food systems, and public health.

    PubMed

    Neff, Roni A; Parker, Cindy L; Kirschenmann, Frederick L; Tinch, Jennifer; Lawrence, Robert S

    2011-09-01

    Peak oil is the phenomenon whereby global oil supplies will peak, then decline, with extraction growing increasingly costly. Today's globalized industrial food system depends on oil for fueling farm machinery, producing pesticides, and transporting goods. Biofuels production links oil prices to food prices. We examined food system vulnerability to rising oil prices and the public health consequences. In the short term, high food prices harm food security and equity. Over time, high prices will force the entire food system to adapt. Strong preparation and advance investment may mitigate the extent of dislocation and hunger. Certain social and policy changes could smooth adaptation; public health has an essential role in promoting a proactive, smart, and equitable transition that increases resilience and enables adequate food for all.

  12. Peak Oil, Food Systems, and Public Health

    PubMed Central

    Parker, Cindy L.; Kirschenmann, Frederick L.; Tinch, Jennifer; Lawrence, Robert S.

    2011-01-01

    Peak oil is the phenomenon whereby global oil supplies will peak, then decline, with extraction growing increasingly costly. Today's globalized industrial food system depends on oil for fueling farm machinery, producing pesticides, and transporting goods. Biofuels production links oil prices to food prices. We examined food system vulnerability to rising oil prices and the public health consequences. In the short term, high food prices harm food security and equity. Over time, high prices will force the entire food system to adapt. Strong preparation and advance investment may mitigate the extent of dislocation and hunger. Certain social and policy changes could smooth adaptation; public health has an essential role in promoting a proactive, smart, and equitable transition that increases resilience and enables adequate food for all. PMID:21778492

  13. High-performance liquid chromatographic determination of 17beta-estradiol and 17beta-estradiol-3-acetate solubilities and diffusion coefficents in silicone elastromeric intravaginal rings.

    PubMed

    Russell, J A; Malcolm, R K; Campbell, K; Woolfson, A D

    2000-07-07

    A rapid, sensitive reversed-phase high-performance liquid chromatographic method has been developed for the determination of in vitro release of 17beta-estradiol and its ester prodrug, 17beta-estradiol-3-acetate, from silicone intravaginal rings. Partial hydrolysis of the acetate under the aqueous conditions provided by the 1% benzalkonium chloride release medium necessitates its conversion to 17beta-estradiol prior to HPLC analysis. Both steroid peaks have been fully resolved from the benzalkonium chloride peaks by the reported chromatographic method, which employs a C18 bonded reversed-phase column, an acetonitrile-water (50:50, v/v) mobile phase and a UV detection wavelength of 281 nm. The peak area versus 17beta-estradiol concentration was found to be linear over the range of 0.0137-1347 microkg ml(-1). The HPLC method has also been used to determine the silicone solubilities and diffusion coefficients of the two related steroids. The almost 100-fold increase in 17beta-estradiol-3-acetate release from the silicone core-type intravaginal rings compared to 17beta-estradiol is shown to be due to a 60-fold increase in silicone solubility and a one and a half-fold increase in diffusitivity. The results demonstrate that an effective estrogen replacement therapy dose of 17beta-estradiol may be administered from a silicone intravaginal reservoir device containing the labile 17beta-estradiol-3-acetate prodrug.

  14. Peak picking and the assessment of separation performance in two-dimensional high performance liquid chromatography

    SciTech Connect

    Guiochon, Georges A; Shalliker, R. Andrew

    2010-01-01

    An algorithm was developed for 2DHPLC that automated the process of peak recognition, measuring their retention times, and then subsequently plotting the information in a two-dimensional retention plane. Following the recognition of peaks, the software then performed a series of statistical assessments of the separation performance, measuring for example, correlation between dimensions, peak capacity and the percentage of usage of the separation space. Peak recognition was achieved by interpreting the first and second derivatives of each respective one-dimensional chromatogram to determine the 1D retention times of each solute and then compiling these retention times for each respective fraction 'cut'. Due to the nature of comprehensive 2DHPLC adjacent cut fractions may contain peaks common to more than one cut fraction. The algorithm determined which components were common in adjacent cuts and subsequently calculated the peak maximum profile by interpolating the space between adjacent peaks. This algorithm was applied to the analysis of a two-dimensional separation of an apple flesh extract separated in a first dimension comprising a cyano stationary phase and an aqueous/THF mobile phase as the first dimension and a second dimension comprising C18-Hydro with an aqueous/MeOH mobile phase. A total of 187 peaks were detected.

  15. The verification phase and reliability of physiological parameters in peak testing of elite wheelchair athletes.

    PubMed

    Leicht, Christof A; Tolfrey, Keith; Lenton, John P; Bishop, Nicolette C; Goosey-Tolfrey, Victoria L

    2013-02-01

    The purpose of this study was (1) to examine the value of a verification phase (VER) in a peak testing protocol and (2) to assess the reliability of peak physiological variables in wheelchair athletes. On two separate days, eight tetraplegic (TETRA), eight paraplegic (PARA) and eight non-spinal cord-injured (NON-SCI) athletes performed treadmill ergometry, consisting of a graded exercise test to exhaustion (GXT) followed by a VER. Peak oxygen uptake (.VO2peak) was compared (1) between GXT and VER and (2) between test days. .VO2peak did not differ between GXT and VER (P = 0.27), and coefficients of variation between GXT and VER were in the range of 2.9 and 6.4 % for all subgroups. Coefficients of variation of .VO2peak between test days were 9.3 % (TETRA), 4.5 % (PARA) and 3.3 % (NON-SCI). It is therefore concluded that whilst a VER can be used for a more robust determination of .VO2peak, a deviation of up to ~6 % between GXT and VER should be considered as acceptable. For between-day analyses, relatively large changes in .VO2peak are required to confirm "true" differences, especially in TETRA athletes. This may be due to their lower aerobic capacity, which results in a larger relative variation compared with the other subgroups.

  16. Reducing Peak Power in Automated Weapon Laying

    DTIC Science & Technology

    2016-02-01

    aiming a weapon is referred to as gun laying. This report describes a method to calculate motion profiles that reach a given lay within the least...amount of time while reducing the amount of peak power required and, therefore, minimizing the forces caused by acceleration. 15. SUBJECT TERMS...Calculating New Acceleration Values 5 Results and Discussions 7 Conclusions 10 Distribution List 11 FIGURES 1 Trapezoidal motion profile 1 2

  17. Efficient wheat germ agglutinin purification with a chitosan-based affinity chromatographic matrix.

    PubMed

    Baieli, María F; Urtasun, Nicolás; Miranda, María V; Cascone, Osvaldo; Wolman, Federico J

    2012-01-01

    An efficient affinity chromatographic matrix based on chitosan for wheat germ agglutinin (WGA) purification was developed. The matrices assayed consisted of chitosan mini-spheres cross-linked with epichlorhydrin 45, 250 or 500 mM. The maximum adsorption capacity of pure WGA - calculated from the corresponding isotherms - was between 43.2 and 48.9 mg/g at pH 5.0 and between 16.6 and 27.6 mg/g at pH 8.5. However, the adsorption of agglutinin from wheat germ extract was higher at pH 8.5. In addition, 0.5 g of mini-spheres cross-linked with epichlorhydrin 250 mM adsorbed 94.5% of the WGA present in 5 mL of the concentrated extract. Acetic acid was able to elute 100% of the adsorbed WGA. The purity of the WGA obtained was greater than 95% and the purification factor was 56.8. The matrix was able to maintain an efficient performance of the purification process for three consecutive cycles. A new method to monitor the purification process by RP-HPLC was developed.

  18. Quantifying peak discharges for historical floods

    USGS Publications Warehouse

    Cook, J.L.

    1987-01-01

    It is usually advantageous to use information regarding historical floods, if available, to define the flood-frequency relation for a stream. Peak stages can sometimes be determined for outstanding floods that occurred many years ago before systematic gaging of streams began. In the United States, this information is usually not available for more than 100-200 years, but in countries with long cultural histories, such as China, historical flood data are available at some sites as far back as 2,000 years or more. It is important in flood studies to be able to assign a maximum discharge rate and an associated error range to the historical flood. This paper describes the significant characteristics and uncertainties of four commonly used methods for estimating the peak discharge of a flood. These methods are: (1) rating curve (stage-discharge relation) extension; (2) slope conveyance; (3) slope area; and (4) step backwater. Logarithmic extensions of rating curves are based on theoretical plotting techniques that results in straight line extensions provided that channel shape and roughness do not change significantly. The slope-conveyance and slope-area methods are based on the Manning equation, which requires specific data on channel size, shape and roughness, as well as the water-surface slope for one or more cross-sections in a relatively straight reach of channel. The slope-conveyance method is used primarily for shaping and extending rating curves, whereas the slope-area method is used for specific floods. The step-backwater method, also based on the Manning equation, requires more cross-section data than the slope-area ethod, but has a water-surface profile convergence characteristic that negates the need for known or estimated water-surface slope. Uncertainties in calculating peak discharge for historical floods may be quite large. Various investigations have shown that errors in calculating peak discharges by the slope-area method under ideal conditions for

  19. Storage peak gas-turbine power unit

    NASA Technical Reports Server (NTRS)

    Tsinkotski, B.

    1980-01-01

    A storage gas-turbine power plant using a two-cylinder compressor with intermediate cooling is studied. On the basis of measured characteristics of a .25 Mw compressor computer calculations of the parameters of the loading process of a constant capacity storage unit (05.3 million cu m) were carried out. The required compressor power as a function of time with and without final cooling was computed. Parameters of maximum loading and discharging of the storage unit were calculated, and it was found that for the complete loading of a fully unloaded storage unit, a capacity of 1 to 1.5 million cubic meters is required, depending on the final cooling.

  20. Circadian rhythm in anaerobic power and capacity.

    PubMed

    Hill, D W; Smith, J C

    1991-03-01

    Anaerobic power and capacity were measured in nine college-age men at four different times of day: 03.00 h, 09.00 h, 15.00 h, and 21.00 h. Modified Wingate tests were performed against a common resistance of 5.5 kg (0.074 +/- 0.004 kg per kg body mass). Peak power was defined as the highest power output during a 5-s period in the test, and anaerobic capacity was defined as the total external work during the 30-s test. Peak power tended to differ across testing times (F = 2.50, p = .10), with the mean at 21.00 h about 8% higher (p less than .05) than at 03.00 h. Anaerobic capacity differed across the times of day (F = 9.58, p less than .01), with the means at 15.00 h and 21.00 h about 5% higher (p less than .05) than at 03.00 h and 09.00 h. These results suggest that there are circadian rhythms in anaerobic power and capacity.

  1. Reversed-phase liquid chromatographic retention and membrane activity relationships of local anesthetics.

    PubMed

    Tsuchiya, Hironori; Mizogami, Maki; Takakura, Ko

    2005-05-06

    The chromatographic retention and membrane activity relationships of local anesthetics were studied to address the possible mechanisms for structure specificity and inflammation-associated decrease of their effects. Five representative drugs (3 mM for each) were reacted with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine liposomes in 25 mM potassium phosphate buffer (pH 5.9-7.9, containing 100 mM NaCl and 0.1 mM EDTA) for 10 min at 37 degrees C and the membrane fluidity changes were analyzed by measuring fluorescence polarization with 1,6-diphenyl-1,3,5-hexatriene. Their capacity factors were determined on octadecyl-, octyl- and phenyl-bonded silica columns with a mobile phase consisting of 25 mM potassium phosphate buffer (pH 5.9-7.9, containing 100 mM NaCl and 0.1 mM EDTA)-methanol (30:70, v/v) at a flow rate of 1.0 ml/min and at a column temperature of 37 degrees C and diode-array detection. Mepivacaine, prilocaine, lidocaine, ropivacaine and bupivacaine fluidized membranes in increasing order of intensity, which agreed with their clinical potency. The relative degree of membrane fluidization correlated with that of retention on an octadecyl stationary phase more significantly than the other phases. Both membrane-fluidizing effects and capacity factors decreased by lowering the reaction and mobile phase pH, being consistent with the hypothesis that anesthetic potency is reduced in inflammation because of tissue acidity. Reversed-phase liquid chromatography appears to be useful for estimating the structure-specific and pH-dependent membrane-fluidizing effects of local anesthetics.

  2. Decision-support software for the industrial-scale chromatographic purification of antibodies.

    PubMed

    Chhatre, Sunil; Thillaivinayagalingam, Pranavan; Francis, Richard; Titchener-Hooker, Nigel J; Newcombe, Anthony R; Keshavarz-Moore, Eli

    2007-01-01

    The high therapeutic and financial value offered by polyclonal antibodies and their fragments has prompted extensive commercialization for the treatment of a wide range of acute clinical indications. Large-scale manufacture typically includes antibody-specific chromatography steps that employ custom-made affinity matrices to separate product-specific IgG from the remainder of the contaminating antibody repertoire. The high cost of such matrices necessitates efficient process design in order to maximize their economic potential. Techniques that identify the most suitable operating conditions for achieving desired levels of manufacturing performance are therefore of significant utility. This paper describes the development of a computer model that incorporates the effects of capacity changes over consecutive chromatographic operational cycles in order to identify combinations of protein load and loading flowrate that satisfy preset constraints of product yield and throughput. The method is illustrated by application to the manufacture of DigiFab, an FDA-approved polyclonal antibody fragment purified from ovine serum, which is used to treat digoxin toxicity (Protherics U.K. Limited). The model was populated with data obtained from scale-down experimental studies of the commercial-scale affinity purification step, which correlated measured changes in matrix capacity with the total protein load and number of resin re-uses. To enable a tradeoff between yield and throughput, output values were integrated together into a single metric by multi-attribute decision-making techniques to identify the most suitable flowrate and feed concentration required for achieving target levels of DigiFab yield and throughput. Results indicated that reducing the flowrate by 70% (from the current level) and using a protein load at the midpoint of the range currently employed at production scale (approximately 200-500 g/L) would provide the most satisfactory tradeoff between yield and

  3. Stability-indicating chromatographic methods for the determination of some oxicams.

    PubMed

    Taha, Elham Anwer; Salama, Nahla Nour; Abdel Fattah, Laila el-Said

    2004-01-01

    Two sensitive and selective methods were developed for the determination of some oxicams, namely, lornoxicam (LOX), tenoxicam (TEX), and meloxicam (MEX), in the presence of their alkaline degradation products. The first method is based on the thin-layer chromatographic separation of the 3 drugs from their alkaline degradation products, followed by densitometric measurement of the intact drug spots for LOX, TEX, and MEX at 380, 370, and 364 nm, respectively. The developing systems used for separation are ethyl acetate-methanol-26% ammonia (17 + 3 + 0.35, v/v/v) for LOX and TEX and chloroform-n-hexane-96.0% acetic acid (18 + 1 + 1, v/v/v) for MEX. The linear ranges were 0.25-6.0 microg/spot for LOX and TEX and 0.5-10 microg/spot for MEX, with mean recoveries of 99.80 +/- 1.32, 100.57 +/- 1.34, and 100.71 +/- 1.57%, respectively. The second method is based on the liquid chromatographic separation of the 3 drugs from their alkaline degradation products on a reversed-phase C18 column, using mobile phases of methanol-acetonitrile-acetate buffer, pH 4.6 (4.5 + 0.5 + 5.0, v/v/v) for LOX and MEX and methanol-acetonitrile-acetate buffer, pH 4.6 (1.9 + 0.1 + 3.0, v/v/v) for TEX at ambient temperature. Quantification is achieved by UV detection at 280 nm, based on peak area. The linear ranges were 0.5-20 microg/mL for LOX and TEX and 1.25-50 microg/mL for MEX, with mean recoveries of 99.81 +/- 1.01, 98.90 +/- 1.61, and 100.86 +/- 1.55%, respectively. The methods were validated according to guidelines of the International Conference on Harmonization. The developed methods were successfully applied to the determination of LOX, TEX, and MEX in bulk powder, laboratory-prepared mixtures containing different percentages of degradation products, and pharmaceutical dosage forms.

  4. Capillary gas chromatographic assay of residual methenamine hippurate in equipment cleaning validation swabs.

    PubMed

    Mirza, T; George, R C; Bodenmiller, J R; Belanich, S A

    1998-02-01

    A capillary gas chromatographic method is described for the determination of methenamine hippurate residue in swabs collected from manufacturing equipment surfaces. Any residual methenamine hippurate remaining on process equipment after cleaning is removed by swabbing with one wet polyester Absorbond swab (4" x 4") pre-moistened with water followed by a dry Absorbond swab. The residual methenamine hippurate is chromatographed on a 30 x 0.32 mm (i.d.) Supelcowax-10 capillary column of 0.25-micron film thickness. The amount of residual methenamine hippurate is determined by comparing the ratio of methenamine hippurate peak area response to that of p-cresol (internal standard) obtained for the sample to a linear calibration curve obtained for a series of standard solutions. The method is demonstrated to be sufficiently linear, accurate, precise, sensitive and rugged for the determination of low levels of methenamine hippurate on equipment surfaces. Using this method, the mean recovery of methenamine hippurate from spiked Absorbond swab samples contained in high density polyethylene bottles was 105.2%, with a relative standard deviation (RSD) of +/- 7.1% (n = 25). The mean recoveries of methenamine hippurate from spiked test plates for '180 Grit' Stainless Steel, Teflon and WARCO White (neoprene and PVC) gasket material were 77.2, 96.1 and 50.6%, with RSDs of +/- 9.4 (n = 25), +/- 4.3 (n = 25) and +/- 36% (n = 20), respectively. Recovery correction factors have been incorporated into the method. The method was successfully applied to the assay of actual equipment cleaning validation swab samples. Stability studies demonstrate that methenamine hippurate is not very stable on the equipment surfaces or in the swabs. It is recommended that the surfaces be swabbed immediately after cleaning and the swabs analyzed within 24 h after sample collection. The results demonstrate that in order to fully validate the cleaning procedures, it is not only necessary to investigate the

  5. Doxylamine: a cause for false-positive gas chromatographic assay for phencyclidine.

    PubMed

    Schaldenbrand, J D; McClatchey, K D; Patel, J A; Muilenberg, M J

    1981-01-01

    A 25-year-old white woman ingested an unknown quantity of doxylamine succinate and flurazepam. Urine immunoassay screen (EMIT-dau) was positive for benzodiazopine and negative for phencyclidine. Subsequent gas chromatographic assay of the urine revealed a markedly positive assay for phencyclidine. Doxylamine was ultimately found to be the cause for the false-positive gas chromatographic assay for phencyclidine.

  6. Gas chromatograph-mass spectrometer (GC/MS) system for quantitative analysis of reactive chemical compounds

    DOEpatents

    Grindstaff, Quirinus G.

    1992-01-01

    Described is a new gas chromatograph-mass spectrometer (GC/MS) system and method for quantitative analysis of reactive chemical compounds. All components of such a GC/MS system external to the oven of the gas chromatograph are programmably temperature controlled to operate at a volatilization temperature specific to the compound(s) sought to be separated and measured.

  7. Refinery Capacity Report

    EIA Publications

    2016-01-01

    Data series include fuel, electricity, and steam purchased for consumption at the refinery; refinery receipts of crude oil by method of transportation; and current and projected atmospheric crude oil distillation, downstream charge, and production capacities. Respondents are operators of all operating and idle petroleum refineries (including new refineries under construction) and refineries shut down during the previous year, located in the 50 states, the District of Columbia, Puerto Rico, the Virgin Islands, Guam, and other U.S. possessions. The Refinery Capacity Report does not contain working and shell storage capacity data. This data is now being collected twice a year as of March 31 and September 30 on the Form EIA-810, "Monthly Refinery Report", and is now released as a separate report Working and Net Available Shell Storage Capacity.

  8. LONE PEAK WILDERNESS STUDY AREA, UTAH.

    USGS Publications Warehouse

    Bromfield, Calvin S.; Patten, Lowell L.

    1984-01-01

    On the basis of a mineral survey, three areas in the Lone Peak Wilderness study area, Utah are classed as having mineral-resource potential. These include the Silver Creek district, near the east boundary of the area, the Alpine district near the southwest boundary, and the White Pine Fork area in the northeast part of the area. The Silver Creek and Alpine districts have probable potential for small deposits of silver, lead, zinc and, in addition, the Silver Creek district has a probable potential for small tungsten deposits. Of more significance, the White Pine Fork area has a probable potential for porphyry-type molybdenum resources.

  9. Probing cosmology with weak lensing peak counts

    SciTech Connect

    Kratochvil, Jan M.; Haiman, Zoltan; May, Morgan

    2010-02-15

    We propose counting peaks in weak lensing (WL) maps, as a function of their height, to probe models of dark energy and to constrain cosmological parameters. Because peaks can be identified in two-dimensional WL maps directly, they can provide constraints that are free from potential selection effects and biases involved in identifying and determining the masses of galaxy clusters. As a pilot study, we have run cosmological N-body simulations to produce WL convergence maps in three models with different constant values of the dark energy equation-of-state parameter, w=-0.8, -1, and -1.2, with a fixed normalization of the primordial power spectrum (corresponding to present-day normalizations of {sigma}{sub 8}=0.742, 0.798, and 0.839, respectively). By comparing the number of WL peaks in eight convergence bins in the range of -0.1<{kappa}<0.4, in multiple realizations of a single simulated 3x3 degree field, we show that the first (last) pair of models differ at the 95% (85%) confidence level. A survey with depth and area comparable to those expected from the Large Synoptic Survey Telescope should have a factor of {approx_equal}50 better parameter sensitivity. These results warrant further investigation, in order to assess the constraints available when marginalization over other uncertain parameters is included, and with the specifications of a realistic survey folded into the analysis. Here we find that relatively low-amplitude peaks ({kappa}{approx}0.03), which typically do not correspond to a single collapsed halo along the line of sight, account for most of the parameter sensitivity. We study a range of smoothing scales and source galaxy redshifts (z{sub s}). With a fixed source galaxy density of 15 arcmin{sup -2}, the best results are provided by the smallest scale we can reliably simulate, 1 arcmin, and z{sub s}=2 provides substantially better sensitivity than z{sub s{<=}}1.5.

  10. SETI at the cosmic blackbody radiation peak

    NASA Astrophysics Data System (ADS)

    Vallee, J. P.

    1990-11-01

    Roughly two-thirds of the past 50 SETI studies have concentrated in or near the 'Water Hole' frequencies (between 18 cm and 21 cm wave-length), with no success so far. Gott (1982) proposed an alternative, namely to look at the frequency where the peak of the 2.735 K Cosmic Blackbody Radiation (CBR) is located. An update is presented here on what little has been done so far there, and on what could be done in the 1990s with current receiver technology.

  11. Calculating weighted estimates of peak streamflow statistics

    USGS Publications Warehouse

    Cohn, Timothy A.; Berenbrock, Charles; Kiang, Julie E.; Mason, Jr., Robert R.

    2012-01-01

    According to the Federal guidelines for flood-frequency estimation, the uncertainty of peak streamflow statistics, such as the 1-percent annual exceedance probability (AEP) flow at a streamgage, can be reduced by combining the at-site estimate with the regional regression estimate to obtain a weighted estimate of the flow statistic. The procedure assumes the estimates are independent, which is reasonable in most practical situations. The purpose of this publication is to describe and make available a method for calculating a weighted estimate from the uncertainty or variance of the two independent estimates.

  12. Panama Canal capacity analysis

    SciTech Connect

    Bronzini, M.S.

    1995-04-27

    Predicting the transit capacities of the various Panama Canal alternatives required analyzing data on present Canal operations, adapting and extending an existing computer simulation model, performing simulation runs for each of the alternatives, and using the simulation model outputs to develop capacity estimates. These activities are summarized in this paper. A more complete account may be found in the project final report (TAMS 1993). Some of the material in this paper also appeared in a previously published paper (Rosselli, Bronzini, and Weekly 1994).

  13. Model-based design of peptide chromatographic purification processes.

    PubMed

    Gétaz, David; Stroehlein, Guido; Butté, Alessandro; Morbidelli, Massimo

    2013-04-05

    In this work we present a general procedure for the model-based optimization of a polypeptide crude mixture purification process through its application to a case of industrial relevance. This is done to show how much modeling can be beneficial to optimize complex chromatographic processes in the industrial environment. The target peptide elution profile was modeled with a two sites adsorption equilibrium isotherm exhibiting two inflection points. The variation of the isotherm parameters with the modifier concentration was accounted for. The adsorption isotherm parameters of the target peptide were obtained by the inverse method. The elution of the impurities was approximated by lumping them into pseudo-impurities and by regressing their adsorption isotherm parameters directly as a function of the corresponding parameters of the target peptide. After model calibration and validation by comparison with suitable experimental data, Pareto optimizations of the process were carried out so as to select the optimal batch process.

  14. Chromatographic hydrophobicity index: pH profile for polyprotic compounds.

    PubMed

    Fuguet, Elisabet; Ràfols, Clara; Bosch, Elisabeth; Rosés, Martí

    2009-11-06

    The Chromatographic Hydrophobicity Index (CHI) has been measured for several diprotic compounds. In order to model the variation of CHI with pH, a general equation for polyprotic compounds which allows the calculation of CHI for each one of the species has been proposed. Different types of diprotic solutes have been selected: neutral acids, neutral bases, and amphiprotic compounds (non-zwitterionic and zwitterionic). The applicability of the model to these complex polyprotic compounds, its advantages and limitations, as well as the information provided by the fits is discussed. In general, the model fits the experimental behaviour of all kind of solutes very well, obtaining the higher hydrophobicity values for the neutral form of the compounds, except for the zwitterionic phenylalanine. The equation and parameters obtained allow an easy calculation of CHI of the compound at any pH value.

  15. Extraction, chromatographic and mass spectrometric methods for lipid analysis.

    PubMed

    Pati, Sumitra; Nie, Ben; Arnold, Robert D; Cummings, Brian S

    2016-05-01

    Lipids make up a diverse subset of biomolecules that are responsible for mediating a variety of structural and functional properties as well as modulating cellular functions such as trafficking, regulation of membrane proteins and subcellular compartmentalization. In particular, phospholipids are the main constituents of biological membranes and play major roles in cellular processes like transmembrane signaling and structural dynamics. The chemical and structural variety of lipids makes analysis using a single experimental approach quite challenging. Research in the field relies on the use of multiple techniques to detect and quantify components of cellular lipidomes as well as determine structural features and cellular organization. Understanding these features can allow researchers to elucidate the biochemical mechanisms by which lipid-lipid and/or lipid-protein interactions take place within the conditions of study. Herein, we provide an overview of essential methods for the examination of lipids, including extraction methods, chromatographic techniques and approaches for mass spectrometric analysis.

  16. Chromatographic evaluation of the toxicity in fish of pesticides.

    PubMed

    Bermúdez-Saldaña, José María; Escuder-Gilabert, Laura; Medina-Hernández, María José; Villanueva-Camañas, Rosa María; Sagrado, Salvador

    2005-01-05

    Ecotoxicity assessment is essential before placing new chemical substances on the market. An investigation of the use of the chromatographic retention (log k) in biopartitioning micellar chromatography (BMC) as an in vitro approach to evaluate the toxicity in fish of pesticides (acute toxicity levels as pLC(50)) is proposed. A heterogeneous data set of 85 pesticides from six chemical families with available experimental fish toxicity data (ECOTOX database from U.S. Environmental Protection Agency (EPA)) was used. For pesticides exhibiting non-polar narcosis mechanism in fish (non-specific toxicity), more reliable models and precise pLC(50) estimations are obtained from log k (quantitative retention-activity relationships, QRAR) than from log P (quantitative structure-activity relationships, QSAR) or ECOSAR (ECOSAR program from U.S. EPA).

  17. Chromatographic separation of neodymium isotopes by using chemical exchange process.

    PubMed

    Ismail, I M; Ibrahim, M; Aly, H F; Nomura, M; Fujii, Y

    2011-05-20

    The neodymium isotope effects were investigated in Nd-malate ligand exchange system using the highly porous cation exchange resin SQS-6. The temperature of the chromatographic columns was kept constant at 50°C by temperature controlled water passed through the columns jackets. The separation coefficient of neodymium isotopes, ɛ's, was calculated from the isotopic ratios precisely measured by means of an ICP mass spectrometer equipped with nine collectors as ion detectors. The separation coefficient, ɛ×10(5), were calculated and found to be 1.4, 4.8, 5.4, 10.6, 16.8 and 20.2 for (143)Nd, (144)Nd, (145)Nd, (146)Nd, (148)Nd and (150)Nd, respectively.

  18. [Thin-layer chromatographic demonstration of the herbicide zenkor].

    PubMed

    Tsvetkova, Ts; Sergeeva, D; Grigorova, D

    1976-01-01

    Established were the thin-layer chromatography conditions for the demonstration of the herbicide Zenkor as a pure substance and a preparation. Comparative experiments were carried out applying Thomson and Stanley's thin-layer chromatography conditions and the authors' personal ones. Most adequate proved to be the following conditions: sorbent-Kieselgel 60F 254 (Merck); solvent -- chloroform: 1,4-dioxan (9:1); developer -- ultraviolet light (authors' technique). Essential with this method is the preliminary (prior to apply the pure substances on the thin-layer chromatographic plaque) moving of the plaque in the indicated mobile phase (authors' technique). Under these thin-layer chromatography conditions work is made feasible and the method is fast and simple, achieving high sensitivity -- 0.5 mug Zenkor.

  19. RAPID MEASUREMENTS OF NEPTUNIUM OXIDATION STATES USING CHROMATOGRAPHIC RESINS

    SciTech Connect

    Diprete, D; C Diprete, C; Mira Malek, M; Eddie Kyser, E

    2009-03-24

    The Savannah River Site's (SRS) H-Canyon facility uses ceric ammonium nitrate (CAN) to separate impure neptunium (Np) from a high sulfate feed stream. The material is processed using a two-pass solvent extraction purification which relies on CAN to oxidize neptunium to Np(VI) during the first pass prior to extraction. Spectrophotometric oxidation-state analyses normally used to validate successful oxidation to Np(VI) prior to extraction were compromised by this feed stream matrix. Therefore, a rapid chromatographic method to validate successful Np oxidation was developed using Eichrom Industries TRU and TEVA{reg_sign} resins. The method was validated and subsequently transferred to existing operations in the process analytical laboratories.

  20. Gas chromatographic determination of oxalic acid in foods.

    PubMed

    Ohkawa, H

    1985-01-01

    A new quantitative gas chromatographic (GC) method has been developed for the determination of oxalic acid in foods. Solid sample is extracted with water (soluble oxalic acid) or 2N hydrochloric acid (total oxalic acid) at room temperature. An aliquot of sample extract is evaporated to dryness, and the oxalic acid in the residue is methylated with 7% hydrochloric acid-methanol. The reaction mixture is extracted with chloroform, and dimethyl oxalate is quantitated by GC. Recovery of oxalic acid added to liquid samples averaged 100.6%; recoveries from extracts of solid samples were 96.2-99.5 and 97.2-100.1% for water and hydrochloric acid extractions, respectively. Results are shown for determination of oxalic acid in spinach and beverages. The technique is simple, rapid, and accurate, and small samples may be used. The limit of determination is 20 micrograms.

  1. Liquid Chromatographic Determination of Amnesic Shellfish Poison in Mussels

    NASA Astrophysics Data System (ADS)

    Duxbury, Mark

    2000-10-01

    A simple, rapid, high-performance liquid chromatographic experiment suitable for undergraduate students is described for determining amnesic shellfish poison in mussels. The poison itself is an unusual naturally occurring amino acid, domoic acid, that has been found in seafood, particularly shellfish, worldwide. The symptoms of poisoning include amnesia (memory loss), loss of balance, mental confusion, nausea, vomiting, diarrhea, coma, and in extreme cases death. The domoic acid is extracted from homogenized mussel tissue by boiling in water for 5 minutes. The homogenate is cooled and centrifuged, and an aliquot of the supernatant is diluted and analyzed by isocratic HPLC using a C18 column and an acetonitrile-water mobile phase at pH 2.5 with UV detection at 242 nm.

  2. Solubilities in supercritical fluids: the application of chromatographic measurement methods

    SciTech Connect

    Smith, R.D.; Udseth, H.R.; Wright, B.W.; Yonker, C.R.

    1987-01-01

    New methods are described for the measurement of the solubilities of solids in supercritical fluids. These methods utilize instrumentation developed for capillary supercritical fluid chromatography consisting of deactivated, small diameter, fused silica tubing, coupled with detection methods based upon on flame ionization and mass spectrometric detectors. The methods involve (a) direct solubility determination where the fused silica capillary is used as an equilibrium cell, and (b) a pressure of threshold solubility technique which resembles chromatography and uses a programmed pressure increase and sensitive detection to determine the onset of solute migration. Results are also presented which suggest that solubilities can be determined, within certain limitations, from actual chromatographic experiments. The methods are illustrated using aromatic hydrocarbons and complex mycotoxins of the trichothecene group.

  3. Gas chromatographic determination of sulphur compounds in town gas.

    PubMed

    Hoshika, Y; Iida, Y

    1977-04-11

    The gas chromatographic (GC) determination of the sulphur compounds in town gas (in the Nagoya area) was studied by using a flame-photometric detector (FPD) and the cold-trap method with liquid oxygen. The column packings used were 25% TCEP on Shimalite (AW, DMCS), 25% TCP on Shimalite (AW, DMCS), 10% PPE on Shimalite TPA, Porapak Q and silica gel. The major components identified were carbonyl sulphide, hydrogen sulphide, carbon disulphide, thiophene and tetrahydrothiophene (THT). The identities of thiophene and THT were also confirmed by GC combined with the use of a quadrupole mass spectrometer. The average concentrations and standard deviations of thiophene and THT were 8.8 +/- 1.8and 124 +/- 35 ng per 0.051, respectively. The latter value corresponds to 0.7 ppm, which is relatively high for the concentration of an odorant.

  4. Fatty acids determination in Bronte pistachios by gas chromatographic method.

    PubMed

    Pantano, Licia; Lo Cascio, Giovanni; Alongi, Angelina; Cammilleri, Gaetano; Vella, Antonio; Macaluso, Andrea; Cicero, Nicola; Migliazzo, Aldo; Ferrantelli, Vincenzo

    2016-10-01

    A gas chromatographic with flame ionization detector (GC-MS FID) method for the identification and quantification of fatty acids based on the extraction of lipids and derivatisation of free acids to form methyl esters was developed and validated. The proposed method was evaluated to a number of standard FAs, and Bronte pistachios samples were used for that purpose and to demonstrate the applicability of the proposed method. In this regard, repeatability, mean and standard deviation of the analytical procedure were calculated. The results obtained have demonstrated oleic acid as the main component of Bronte pistachios (72.2%) followed by linoleic acid (13.4%) and showed some differences in composition with respect to Tunisian, Turkish and Iranian pistachios.

  5. Soil chromatographic movement of technetium-99 through selected Minnesota soils

    SciTech Connect

    Balogh, J.C.; Grigal, D.F.

    1980-11-01

    We monitored the movement of technetium-99 through 41 samples of Minnesota soils, using soil column layer chromatography (CLC), a modification of soil thin layer chromatography. Under the aerobic conditions of soil CLC, /sup 99/Tc occurs as the pertechnetate anion. Pertechnetate movement in the soils was characterized by the traditional R/sub f/ chromatographic parameter. Reduced R/sub f/ values were statistically related to elevated levels of soil organic matter. Complexation of /sup 99/Tc, related to soil organic matter, was weak. Elution patterns of /sup 99/Tc in the soil CLC columns were asymmetric, with pertechnetate retardation associated with both hydrodynamic dispersion and weak retention. Pertechnetate was less mobile than was Cl/sup -/ in selected soils by soil CLC.

  6. Improved Chromatographic Separation of Sitagliptin Phosphate and Metformin Hydrochloride

    PubMed Central

    Hendy, Moataz S.

    2015-01-01

    New UPLC method was developed for determination of sitagliptin and metformin using Symmetry C18 column (100 mm × 2.1 mm, 2.2 μm) and isocratic elution (methanol 20%), pH (3.5) as a mobile phase. The ultraviolet detector was operated at 220 nm and the column temperature was 50°C. Linearity parameters were acceptable over the concentration ranges of 2-12 μgml-1 and 5-35 μgml-1 for sitagliptin and metformin, respectively. The variables were premeditated to adjust the chromatographic conditions using design of experiment. The proposed method was proved to be accurate for the quality control of the mentioned drugs in their pharmaceutical dosage form. PMID:26759536

  7. [Advancement of colloidal gold chromatographic technique in screening of ochratoxin A].

    PubMed

    Zhou, Wei-lu; Wang, Yu-ting; Kong, Wei-jun; Yang, Mei-hua; Zhao, Ming; Ou-Yang, Zhen

    2015-08-01

    Ochratoxin A (OTA) is a toxic secondary metabolite mainly produced by Aspergillus and Penicillium species, existing in a variety of foodstuffs and Chinese medicines. OTA is difficult to be detected in practice because of the characteristics such as trace amounts, toxicity, existing in complex matrices. In the numerous detection technologies, colloidal gold chromatographic techniques are highly sensitive, specific, cost-effective and user-friendly, and are being used increasingly for OTA screening. Recently, with the development of aptamer technology and its application in chromatographic technique, a newly colloidal gold aptamer chromatographic technique has been developed. This review elaborates the structures and principles of both traditional and newly colloidal gold chromatographic techniques, focuses on newly colloidal gold aptamer chromatographic technique, summarizes and compares their use in rapid detection of OTA. Finally, in order to provide a reference for better research of related work, the development trends of this novel technique are prospected.

  8. Chemical characterization of Brickellia cavanillesii (Asteraceae) using gas chromatographic methods.

    PubMed

    Eshiet, Etetor R; Zhu, Jinqiu; Anderson, Todd A; Smith, Ernest E

    2014-03-01

    A methanol extract of lyophilized Brickellia cavanillesii was quantitatively analyzed using gas chromatographic (GC) techniques. The chromatographic methods employed were (i) GC-flame ionization detector (GC-FID), (ii) GC-mass spectrometry (GC-MS), and (iii) purge and trap GC-MS (P&T GC-MS). Thirteen compounds were identified with a quality match of 90% and above using GC-MS. The compounds were (1) Cyclohexene, 6-ethenyl-6-methyl-1-(1-methylethyl)-3-(1-methylethylidene)-, (S)-; (2) Bicylo (2.2.1) heptan-2-one, 1, 7, 7-trimethyl-(1S, 4S)-; (3) Phenol, 2-methoxy-4-(1-propenyl)-; (4) Benzene, 1-(1, 5-dimethyl-4-hexenyl)-4-methyl-; (5) Naphthalene, 1, 2, 3, 5, 6, 8a-hexahydro4, 7-dimethyl-1-1-(1-methylethyl)-, (1S-cis)-; (6) Phenol, 2-methoxy-; (7) Benzaldehyde, 3-hydroxy-4-methoxy-; (8) 11, 13-Eicosadienoic acid, methyl ester; (9) 2-Furancarboxaldehyde, 5-methyl-; (10) Maltol; (11) Phenol; (12) Hydroquinone; (13) 1H-Indene, 1-ethylideneoctahydro-7a-methyl-, (1E, 3a.alpha, 7a.beta.). Other compounds (14) 3-methyl butanal; (15) (D)-Limonene; (16) 1-methyl-4-(1-methyl ethyl) benzene; (17) Butanoic acid methyl ester; (18) 2-methyl propanal; (19) 2-butanone; (20) 2-pentanone; and (21) 2-methyl butane were also identified when P&T GC-MS was performed. Of the 21 compounds identified, 12 were validated using chemical standards. The identified compounds were found to be terpenes, derivatives of terpenes, esters, ketones, aldehydes, and phenol-derived aromatic compounds; these are the primary constituents of the essential oils of many plants and flowers.

  9. Chemical characterization of Brickellia cavanillesii (Asteraceae) using gas chromatographic methods

    PubMed Central

    Eshiet, Etetor R; Zhu, Jinqiu; Anderson, Todd A; Smith, Ernest E

    2014-01-01

    A methanol extract of lyophilized Brickellia cavanillesii was quantitatively analyzed using gas chromatographic (GC) techniques. The chromatographic methods employed were (i) GC-flame ionization detector (GC-FID), (ii) GC-mass spectrometry (GC-MS), and (iii) purge and trap GC-MS (P&T GC-MS). Thirteen compounds were identified with a quality match of 90% and above using GC-MS. The compounds were (1) Cyclohexene, 6-ethenyl-6-methyl-1-(1-methylethyl)-3-(1-methylethylidene)-, (S)-; (2) Bicylo (2.2.1) heptan-2-one, 1, 7, 7-trimethyl-(1S, 4S)-; (3) Phenol, 2-methoxy-4-(1-propenyl)-; (4) Benzene, 1-(1, 5-dimethyl-4-hexenyl)-4-methyl-; (5) Naphthalene, 1, 2, 3, 5, 6, 8a-hexahydro4, 7-dimethyl-1-1-(1-methylethyl)-, (1S-cis)-; (6) Phenol, 2-methoxy-; (7) Benzaldehyde, 3-hydroxy-4-methoxy-; (8) 11, 13-Eicosadienoic acid, methyl ester; (9) 2-Furancarboxaldehyde, 5-methyl-; (10) Maltol; (11) Phenol; (12) Hydroquinone; (13) 1H-Indene, 1-ethylideneoctahydro-7a-methyl-, (1E, 3a.alpha, 7a.beta.). Other compounds (14) 3-methyl butanal; (15) (D)-Limonene; (16) 1-methyl-4-(1-methyl ethyl) benzene; (17) Butanoic acid methyl ester; (18) 2-methyl propanal; (19) 2-butanone; (20) 2-pentanone; and (21) 2-methyl butane were also identified when P&T GC-MS was performed. Of the 21 compounds identified, 12 were validated using chemical standards. The identified compounds were found to be terpenes, derivatives of terpenes, esters, ketones, aldehydes, and phenol-derived aromatic compounds; these are the primary constituents of the essential oils of many plants and flowers. PMID:24804069

  10. Beyond the Peak - Tactile Temporal Discrimination Does Not Correlate with Individual Peak Frequencies in Somatosensory Cortex.

    PubMed

    Baumgarten, Thomas J; Schnitzler, Alfons; Lange, Joachim

    2017-01-01

    The human sensory systems constantly receive input from different stimuli. Whether these stimuli are integrated into a coherent percept or segregated and perceived as separate events, is critically determined by the temporal distance of the stimuli. This temporal distance has prompted the concept of temporal integration windows or perceptual cycles. Although this concept has gained considerable support, the neuronal correlates are still discussed. Studies suggested that neuronal oscillations might provide a neuronal basis for such perceptual cycles, i.e., the cycle lengths of alpha oscillations in visual cortex and beta oscillations in somatosensory cortex might determine the length of perceptual cycles. Specifically, recent studies reported that the peak frequency (the frequency with the highest spectral power) of alpha oscillations in visual cortex correlates with subjects' ability to discriminate two visual stimuli. In the present study, we investigated whether peak frequencies in somatosensory cortex might serve as the correlate of perceptual cycles in tactile discrimination. Despite several different approaches, we were unable to find a significant correlation between individual peak frequencies in the alpha- and beta-band and individual discrimination abilities. In addition, analysis of Bayes factor provided evidence that peak frequencies and discrimination thresholds are unrelated. The results suggest that perceptual cycles in the somatosensory domain are not necessarily to be found in the peak frequency, but in other frequencies. We argue that studies based solely on analysis of peak frequencies might thus miss relevant information.

  11. PeakVizor: Visual Analytics of Peaks in Video Clickstreams from Massive Open Online Courses.

    PubMed

    Chen, Qing; Chen, Yuanzhe; Liu, Dongyu; Shi, Conglei; Wu, Yingcai; Qu, Huamin

    2016-10-01

    Massive open online courses (MOOCs) aim to facilitate open-access and massive-participation education. These courses have attracted millions of learners recently. At present, most MOOC platforms record the web log data of learner interactions with course videos. Such large amounts of multivariate data pose a new challenge in terms of analyzing online learning behaviors. Previous studies have mainly focused on the aggregate behaviors of learners from a summative view; however, few attempts have been made to conduct a detailed analysis of such behaviors. To determine complex learning patterns in MOOC video interactions, this paper introduces a comprehensive visualization system called PeakVizor. This system enables course instructors and education experts to analyze the "peaks" or the video segments that generate numerous clickstreams. The system features three views at different levels: the overview with glyphs to display valuable statistics regarding the peaks detected; the flow view to present spatio-temporal information regarding the peaks; and the correlation view to show the correlation between different learner groups and the peaks. Case studies and interviews conducted with domain experts have demonstrated the usefulness and effectiveness of PeakVizor, and new findings about learning behaviors in MOOC platforms have been reported.

  12. Lung function parameters improve prediction of VO2peak in an elderly population: The Generation 100 study

    PubMed Central

    Stensvold, Dorthe; Halvorsen, Thomas; Wisløff, Ulrik; Langhammer, Arnulf; Steinshamn, Sigurd

    2017-01-01

    Peak oxygen uptake (VO2peak) is an indicator of cardiovascular health and a useful tool for risk stratification. Direct measurement of VO2peak is resource-demanding and may be contraindicated. There exist several non-exercise models to estimate VO2peak that utilize easily obtainable health parameters, but none of them includes lung function measures or hemoglobin concentrations. We aimed to test whether addition of these parameters could improve prediction of VO2peak compared to an established model that includes age, waist circumference, self-reported physical activity and resting heart rate. We included 1431 subjects aged 69-77 years that completed a laboratory test of VO2peak, spirometry, and a gas diffusion test. Prediction models for VO2peak were developed with multiple linear regression, and goodness of fit was evaluated. Forced expiratory volume in one second (FEV1), diffusing capacity of the lung for carbon monoxide and blood hemoglobin concentration significantly improved the ability of the established model to predict VO2peak. The explained variance of the model increased from 31% to 48% for men and from 32% to 38% for women (p<0.001). FEV1, diffusing capacity of the lungs for carbon monoxide and hemoglobin concentration substantially improved the accuracy of VO2peak prediction when added to an established model in an elderly population. PMID:28319189

  13. Outreach Plans for Storm Peak Laboratory

    NASA Astrophysics Data System (ADS)

    Hallar, A. G.; McCubbin, I. B.

    2006-12-01

    The Desert Research Institute (DRI) operates a high elevation facility, Storm Peak Laboratory (SPL), located on the west summit of Mt. Werner in the Park Range near Steamboat Springs, Colorado at an elevation 10,500 ft. SPL provides an ideal location for long-term research on the interactions of atmospheric aerosol and gas- phase chemistry with cloud and natural radiation environments. SPL includes an office-type laboratory room for computer and instrumentation setup with outside air ports and cable access to the roof deck, a full kitchen and two bunk rooms with sleeping space for nine persons. We plan to create a unique summer undergraduate education experiences for students of diversity at Storm Peak Laboratory. As stressed by the College Pathways to Science Education Standards [Siebert and McIntosh, 2001], to support changes in K-12 science education transformations must first be made at the college level, including inquiry-oriented opportunities to engage in meaningful research. These workshops will be designed to allow students to experience the excitement of science, increasing their likelihood of pursing careers within the fields of scientific education or research.

  14. Equivalence principle and the baryon acoustic peak

    NASA Astrophysics Data System (ADS)

    Baldauf, Tobias; Mirbabayi, Mehrdad; Simonović, Marko; Zaldarriaga, Matias

    2015-08-01

    We study the dominant effect of a long wavelength density perturbation δ (λL) on short distance physics. In the nonrelativistic limit, the result is a uniform acceleration, fixed by the equivalence principle, and typically has no effect on statistical averages due to translational invariance. This same reasoning has been formalized to obtain a "consistency condition" on the cosmological correlation functions. In the presence of a feature, such as the acoustic peak at ℓBAO, this naive expectation breaks down for λL<ℓBAO. We calculate a universal piece of the three-point correlation function in this regime. The same effect is shown to underlie the spread of the acoustic peak, and is calculable to all orders in the long modes. This can be used to improve the result of perturbative calculations—a technique known as "infra-red resummation"—and is explicitly applied to the one-loop calculation of the power spectrum. Finally, the success of baryon acoustic oscillation reconstruction schemes is argued to be another empirical evidence for the validity of the results.

  15. Estimation of cardiac reserve by peak power: validation and initial application of a simplified index

    NASA Technical Reports Server (NTRS)

    Armstrong, G. P.; Carlier, S. G.; Fukamachi, K.; Thomas, J. D.; Marwick, T. H.

    1999-01-01

    OBJECTIVES: To validate a simplified estimate of peak power (SPP) against true (invasively measured) peak instantaneous power (TPP), to assess the feasibility of measuring SPP during exercise and to correlate this with functional capacity. DESIGN: Development of a simplified method of measurement and observational study. SETTING: Tertiary referral centre for cardiothoracic disease. SUBJECTS: For validation of SPP with TPP, seven normal dogs and four dogs with dilated cardiomyopathy were studied. To assess feasibility and clinical significance in humans, 40 subjects were studied (26 patients; 14 normal controls). METHODS: In the animal validation study, TPP was derived from ascending aortic pressure and flow probe, and from Doppler measurements of flow. SPP, calculated using the different flow measures, was compared with peak instantaneous power under different loading conditions. For the assessment in humans, SPP was measured at rest and during maximum exercise. Peak aortic flow was measured with transthoracic continuous wave Doppler, and systolic and diastolic blood pressures were derived from brachial sphygmomanometry. The difference between exercise and rest simplified peak power (Delta SPP) was compared with maximum oxygen uptake (VO(2)max), measured from expired gas analysis. RESULTS: SPP estimates using peak flow measures correlated well with true peak instantaneous power (r = 0.89 to 0.97), despite marked changes in systemic pressure and flow induced by manipulation of loading conditions. In the human study, VO(2)max correlated with Delta SPP (r = 0.78) better than Delta ejection fraction (r = 0.18) and Delta rate-pressure product (r = 0.59). CONCLUSIONS: The simple product of mean arterial pressure and peak aortic flow (simplified peak power, SPP) correlates with peak instantaneous power over a range of loading conditions in dogs. In humans, it can be estimated during exercise echocardiography, and correlates with maximum oxygen uptake better than ejection

  16. Peak Wind Tool for General Forecasting

    NASA Technical Reports Server (NTRS)

    Barrett, Joe H., III

    2010-01-01

    The expected peak wind speed of the day is an important forecast element in the 45th Weather Squadron's (45 WS) daily 24-Hour and Weekly Planning Forecasts. The forecasts are used for ground and space launch operations at the Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS). The 45 WS also issues wind advisories for KSC/CCAFS when they expect wind gusts to meet or exceed 25 kt, 35 kt and 50 kt thresholds at any level from the surface to 300 ft. The 45 WS forecasters have indicated peak wind speeds are challenging to forecast, particularly in the cool season months of October - April. In Phase I of this task, the Applied Meteorology Unit (AMU) developed a tool to help the 45 WS forecast non-convective winds at KSC/CCAFS for the 24-hour period of 0800 to 0800 local time. The tool was delivered as a Microsoft Excel graphical user interface (GUI). The GUI displayed the forecast of peak wind speed, 5-minute average wind speed at the time of the peak wind, timing of the peak wind and probability the peak speed would meet or exceed 25 kt, 35 kt and 50 kt. For the current task (Phase II ), the 45 WS requested additional observations be used for the creation of the forecast equations by expanding the period of record (POR). Additional parameters were evaluated as predictors, including wind speeds between 500 ft and 3000 ft, static stability classification, Bulk Richardson Number, mixing depth, vertical wind shear, temperature inversion strength and depth and wind direction. Using a verification data set, the AMU compared the performance of the Phase I and II prediction methods. Just as in Phase I, the tool was delivered as a Microsoft Excel GUI. The 45 WS requested the tool also be available in the Meteorological Interactive Data Display System (MIDDS). The AMU first expanded the POR by two years by adding tower observations, surface observations and CCAFS (XMR) soundings for the cool season months of March 2007 to April 2009. The POR was expanded

  17. Improving the productivity of a multidimensional chromatographic preparative system by collecting pure chemicals after each of three chromatographic dimensions.

    PubMed

    Sciarrone, Danilo; Pantò, Sebastiano; Donato, Paola; Mondello, Luigi

    2016-12-02

    The enhanced sample collection capability of a heart-cutting three-dimensional GC-prep system is reported. In its original configuration, a highly pure component can be usually collected after the last (3D) column outlet by means of a dedicated preparative station. The latter is located after the last chromatographic column, and this poses the requirement for multiple heart cuts even for those components showing satisfactory degree of purity after the first (or second) separation dimension. The feasibility to collect pure components after each chromatographic dimension is here described, employing a three-dimension MDGC system equipped with high-temperature valves, located inside the first and second GC ovens, with the aim to improve the productivity of the collection procedure. In addition to a commercial preparative collector located at the 3D outlet, two laboratory-made collection systems were applied in the first and second dimension, reached by the effluent to be collected trough a high-temperature valve switching the heart-cut fraction between either the detector (FID), or the collector. Highly pure sesquiterpene components were collected, namely: patchouli alcohol after the first column [poly(5% diphenyl/95% dimethylsiloxane)], α-bulnesene after a second column coated with high molecular weight polyethylene glycol, and α-guaiene after an ionic-liquid based column (SLB-IL60), used as the third dimension. Purity levels ranging from 85 to 95% were achieved with an average collection recovery of 90% (n=5). The following average amounts were collected per run: 160μg for α-guaiene, 295μg for α-bulnesene, and 496μg for patchouli alcohol.

  18. Cardiopulmonary exercise test in chronic heart failure: beyond peak oxygen consumption.

    PubMed

    Franco, Veronica

    2011-03-01

    Patients with cardiovascular diseases commonly present with exercise intolerance, clinically manifest as shortness of breath and fatigue, and these symptoms have important prognostic implications. Cardiopulmonary exercise testing is a well-established method for evaluation of cardiopulmonary diseases. It provides an objective assessment of maximal aerobic capacity (peak VO(2)), estimates prognosis, and allows the physician to discriminate among many subtle and often overlapping etiologies. This review focuses on the evaluation of important exercise parameters, in addition to the peak VO(2), during cardiopulmonary exercise testing.

  19. Uncertainty in adaptive capacity

    NASA Astrophysics Data System (ADS)

    Adger, W. Neil; Vincent, Katharine

    2005-03-01

    The capacity to adapt is a critical element of the process of adaptation: it is the vector of resources that represent the asset base from which adaptation actions can be made. Adaptive capacity can in theory be identified and measured at various scales, from the individual to the nation. The assessment of uncertainty within such measures comes from the contested knowledge domain and theories surrounding the nature of the determinants of adaptive capacity and the human action of adaptation. While generic adaptive capacity at the national level, for example, is often postulated as being dependent on health, governance and political rights, and literacy, and economic well-being, the determinants of these variables at national levels are not widely understood. We outline the nature of this uncertainty for the major elements of adaptive capacity and illustrate these issues with the example of a social vulnerability index for countries in Africa. To cite this article: W.N. Adger, K. Vincent, C. R. Geoscience 337 (2005).

  20. BUFFALO PEAKS WILDERNESS STUDY AREA, COLORADO.

    USGS Publications Warehouse

    Hedlund, D.C.; Wood, R.H.

    1984-01-01

    Field investigations were conducted to evaluate the mineral-resource potential of the Buffalo Peaks Wilderness Study Area, Colorado. On the basis of this study there is a probable mineral-resource potential for silver vein and bedding replacement deposits along the Weston Pass fault zone, for hydrothermal vein-type uranium deposits in the vicinity of the Parkdale iron pit, and for gold vein deposits in the parts of the Granite and Four Mile districts that are within the wilderness study area. A probable barite resource potential occurs at Rough and Tumbling Creek and near Spring Creek on the east side of the study area. There is little promise for the occurrence of energy resources.

  1. Do we see an 'Iron Peak' ?

    NASA Astrophysics Data System (ADS)

    Erlykin, A. D.; Wolfendale, A. W.

    2011-04-01

    An update of the fine structure in the cosmic ray (CR) energy spectrum at PeV and tens of PeV energies is presented. The existence of the bump at 50-80 PeV found in the GAMMA experiment is supported by 9 other experiments. If it is a real feature it might indicate the existence of the so called 'Iron Peak', i.e. the end of the contribution of a 'Single Source' to the background of CR from other sources. We argue that the new feature in the fine structure of the CR energy spectrum makes the evidence in favour of the presence of a 'Single Source' stronger than before.

  2. Sample distribution in peak mode isotachophoresis

    SciTech Connect

    Rubin, Shimon; Schwartz, Ortal; Bercovici, Moran

    2014-01-15

    We present an analytical study of peak mode isotachophoresis (ITP), and provide closed form solutions for sample distribution and electric field, as well as for leading-, trailing-, and counter-ion concentration profiles. Importantly, the solution we present is valid not only for the case of fully ionized species, but also for systems of weak electrolytes which better represent real buffer systems and for multivalent analytes such as proteins and DNA. The model reveals two major scales which govern the electric field and buffer distributions, and an additional length scale governing analyte distribution. Using well-controlled experiments, and numerical simulations, we verify and validate the model and highlight its key merits as well as its limitations. We demonstrate the use of the model for determining the peak concentration of focused sample based on known buffer and analyte properties, and show it differs significantly from commonly used approximations based on the interface width alone. We further apply our model for studying reactions between multiple species having different effective mobilities yet co-focused at a single ITP interface. We find a closed form expression for an effective-on rate which depends on reactants distributions, and derive the conditions for optimizing such reactions. Interestingly, the model reveals that maximum reaction rate is not necessarily obtained when the concentration profiles of the reacting species perfectly overlap. In addition to the exact solutions, we derive throughout several closed form engineering approximations which are based on elementary functions and are simple to implement, yet maintain the interplay between the important scales. Both the exact and approximate solutions provide insight into sample focusing and can be used to design and optimize ITP-based assays.

  3. Caffeine supplementation and peak anaerobic power output.

    PubMed

    Glaister, Mark; Muniz-Pumares, Daniel; Patterson, Stephen D; Foley, Paul; McInnes, Gillian

    2015-01-01

    The aim of this study was to investigate the effects of caffeine supplementation on peak anaerobic power output (Wmax). Using a counterbalanced, randomised, double-blind, placebo-controlled design, 14 well-trained men completed three trials of a protocol consisting of a series of 6-s cycle ergometer sprints, separated by 5-min passive recovery periods. Sprints were performed at progressively increasing torque factors to determine the peak power/torque relationship and Wmax. Apart from Trial 1 (familiarisation), participants ingested a capsule containing 5 mg·kg(-1) of caffeine or placebo, one hour before each trial. The effects of caffeine on blood lactate were investigated using capillary samples taken after each sprint. The torque factor which produced Wmax was not significantly different (p ≥ 0.05) between the caffeine (1.15 ± 0.08 N·m·kg(-1)) and placebo (1.13 ± 0.10 N·m·kg(-1)) trials. There was, however, a significant effect (p < 0.05) of supplementation on Wmax, with caffeine producing a higher value (1885 ± 303 W) than placebo (1835 ± 290 W). Analysis of the blood lactate data revealed a significant (p < 0.05) torque factor × supplement interaction with values being significantly higher from the sixth sprint (torque factor 1.0 N·m·kg(-1)) onwards following caffeine supplementation. The results of this study confirm previous reports that caffeine supplementation significantly increases blood lactate and Wmax. These findings may explain why the majority of previous studies, which have used fixed-torque factors of around 0.75 N·m·kg(-1) and thereby failing to elicit Wmax, have failed to find an effect of caffeine on sprinting performance.

  4. A new method for the determination of peak distribution across a two-dimensional separation space for the identification of optimal column combinations.

    PubMed

    Leonhardt, Juri; Teutenberg, Thorsten; Buschmann, Greta; Gassner, Oliver; Schmidt, Torsten C

    2016-11-01

    For the identification of the optimal column combinations, a comparative orthogonality study of single columns and columns coupled in series for the first dimension of a microscale two-dimensional liquid chromatographic approach was performed. In total, eight columns or column combinations were chosen. For the assessment of the optimal column combination, the orthogonality value as well as the peak distributions across the first and second dimension was used. In total, three different methods of orthogonality calculation, namely the Convex Hull, Bin Counting, and Asterisk methods, were compared. Unfortunately, the first two methods do not provide any information of peak distribution. The third method provides this important information, but is not optimal when only a limited number of components are used for method development. Therefore, a new concept for peak distribution assessment across the separation space of two-dimensional chromatographic systems and clustering detection was developed. It could be shown that the Bin Counting method in combination with additionally calculated histograms for the respective dimensions is well suited for the evaluation of orthogonality and peak clustering. The newly developed method could be used generally in the assessment of 2D separations. Graphical Abstract ᅟ.

  5. A high-resolution peak fractionation approach for streamlined screening of nuclear-factor-E2-related factor-2 activators in Salvia miltiorrhiza.

    PubMed

    Zhang, Hui; Luo, Li-Ping; Song, Hui-Peng; Hao, Hai-Ping; Zhou, Ping; Qi, Lian-Wen; Li, Ping; Chen, Jun

    2014-01-24

    Generation of a high-purity fraction library for efficiently screening active compounds from natural products is challenging because of their chemical diversity and complex matrices. In this work, a strategy combining high-resolution peak fractionation (HRPF) with a cell-based assay was proposed for target screening of bioactive constituents from natural products. In this approach, peak fractionation was conducted under chromatographic conditions optimized for high-resolution separation of the natural product extract. The HRPF approach was automatically performed according to the predefinition of certain peaks based on their retention times from a reference chromatographic profile. The corresponding HRPF database was collected with a parallel mass spectrometer to ensure purity and characterize the structures of compounds in the various fractions. Using this approach, a set of 75 peak fractions on the microgram scale was generated from 4mg of the extract of Salvia miltiorrhiza. After screening by an ARE-luciferase reporter gene assay, 20 diterpene quinones were selected and identified, and 16 of these compounds were reported to possess novel Nrf2 activation activity. Compared with conventional fixed-time interval fractionation, the HRPF approach could significantly improve the efficiency of bioactive compound discovery and facilitate the uncovering of minor active components.

  6. Panel on Capacity Building

    NASA Astrophysics Data System (ADS)

    Elhadani, D.

    The demonstration was made that space technologies are an important tool for developing countries. But the fundamental question is how those countries could integrate such technologies, in an effective an operational way, in the process of resources management and administration. Capacity building is a cornerstone in any strategy to set up a national programme or infrastructure for the use of space technologies. The proposed presentation attempts to bring the first elements on the actual uses of space technology in developing countries compared to their needs, the role of training activities and programs in the capacity building process as well as the role of international cooperation and what are the required conditions to ensure sustainability of the established capacities.

  7. Dual capacity reciprocating compressor

    DOEpatents

    Wolfe, R.W.

    1984-10-30

    A multi-cylinder compressor particularly useful in connection with northern climate heat pumps and in which different capacities are available in accordance with reversing motor rotation is provided with an eccentric cam on a crank pin under a fraction of the connecting rods, and arranged for rotation upon the crank pin between opposite positions 180[degree] apart so that with cam rotation on the crank pin such that the crank throw is at its normal maximum value all pistons pump at full capacity, and with rotation of the crank shaft in the opposite direction the cam moves to a circumferential position on the crank pin such that the overall crank throw is zero. Pistons whose connecting rods ride on a crank pin without a cam pump their normal rate with either crank rotational direction. Thus a small clearance volume is provided for any piston that moves when in either capacity mode of operation. 6 figs.

  8. Dual capacity reciprocating compressor

    DOEpatents

    Wolfe, Robert W.

    1984-01-01

    A multi-cylinder compressor 10 particularly useful in connection with northern climate heat pumps and in which different capacities are available in accordance with reversing motor 16 rotation is provided with an eccentric cam 38 on a crank pin 34 under a fraction of the connecting rods, and arranged for rotation upon the crank pin between opposite positions 180.degree. apart so that with cam rotation on the crank pin such that the crank throw is at its normal maximum value all pistons pump at full capacity, and with rotation of the crank shaft in the opposite direction the cam moves to a circumferential position on the crank pin such that the overall crank throw is zero. Pistons 24 whose connecting rods 30 ride on a crank pin 36 without a cam pump their normal rate with either crank rotational direction. Thus a small clearance volume is provided for any piston that moves when in either capacity mode of operation.

  9. Capacity Maximizing Constellations

    NASA Technical Reports Server (NTRS)

    Barsoum, Maged; Jones, Christopher

    2010-01-01

    Some non-traditional signal constellations have been proposed for transmission of data over the Additive White Gaussian Noise (AWGN) channel using such channel-capacity-approaching codes as low-density parity-check (LDPC) or turbo codes. Computational simulations have shown performance gains of more than 1 dB over traditional constellations. These gains could be translated to bandwidth- efficient communications, variously, over longer distances, using less power, or using smaller antennas. The proposed constellations have been used in a bit-interleaved coded modulation system employing state-ofthe-art LDPC codes. In computational simulations, these constellations were shown to afford performance gains over traditional constellations as predicted by the gap between the parallel decoding capacity of the constellations and the Gaussian capacity

  10. Geothermal Plant Capacity Factors

    SciTech Connect

    Greg Mines; Jay Nathwani; Christopher Richard; Hillary Hanson; Rachel Wood

    2015-01-01

    The capacity factors recently provided by the Energy Information Administration (EIA) indicated this plant performance metric had declined for geothermal power plants since 2008. Though capacity factor is a term commonly used by geothermal stakeholders to express the ability of a plant to produce power, it is a term frequently misunderstood and in some instances incorrectly used. In this paper we discuss how this capacity factor is defined and utilized by the EIA, including discussion on the information that the EIA requests from operations in their 923 and 860 forms that are submitted both monthly and annually by geothermal operators. A discussion is also provided regarding the entities utilizing the information in the EIA reports, and how those entities can misinterpret the data being supplied by the operators. The intent of the paper is to inform the facility operators as the importance of the accuracy of the data that they provide, and the implications of not providing the correct information.

  11. Reductions in labour capacity from heat stress under climate warming

    NASA Astrophysics Data System (ADS)

    Dunne, John P.; Stouffer, Ronald J.; John, Jasmin G.

    2013-06-01

    A fundamental aspect of greenhouse-gas-induced warming is a global-scale increase in absolute humidity. Under continued warming, this response has been shown to pose increasingly severe limitations on human activity in tropical and mid-latitudes during peak months of heat stress. One heat-stress metric with broad occupational health applications is wet-bulb globe temperature. We combine wet-bulb globe temperatures from global climate historical reanalysis and Earth System Model (ESM2M) projections with industrial and military guidelines for an acclimated individual's occupational capacity to safely perform sustained labour under environmental heat stress (labour capacity)--here defined as a global population-weighted metric temporally fixed at the 2010 distribution. We estimate that environmental heat stress has reduced labour capacity to 90% in peak months over the past few decades. ESM2M projects labour capacity reduction to 80% in peak months by 2050. Under the highest scenario considered (Representative Concentration Pathway 8.5), ESM2M projects labour capacity reduction to less than 40% by 2200 in peak months, with most tropical and mid-latitudes experiencing extreme climatological heat stress. Uncertainties and caveats associated with these projections include climate sensitivity, climate warming patterns, CO2 emissions, future population distributions, and technological and societal change.

  12. DOUBLE-PEAKED NARROW-LINE ACTIVE GALACTIC NUCLEI. II. THE CASE OF EQUAL PEAKS

    SciTech Connect

    Smith, K. L.; Shields, G. A.; Salviander, S.; Stevens, A. C.; Rosario, D. J. E-mail: shields@astro.as.utexas.edu E-mail: acs0196@mail.utexas.edu

    2012-06-10

    Active galactic nuclei (AGNs) with double-peaked narrow lines (DPAGNs) may be caused by kiloparsec-scale binary AGNs, bipolar outflows, or rotating gaseous disks. We examine the class of DPAGNs in which the two narrow-line components have closely similar intensity as being especially likely to involve disks or jets. Two spectroscopic indicators support this likelihood. For DPAGNs from Smith et al., the 'equal-peaked' objects (EPAGNs) have [Ne V]/[O III]ratios lower than for a control sample of non-double-peaked AGNs. This is unexpected for a pair of normal AGNs in a galactic merger, but may be consistent with [O III] emission from a rotating ring with relatively little gas at small radii. Also, [O III]/H{beta} ratios of the redshifted and blueshifted systems in the EPAGN are more similar to each other than in a control sample, suggestive of a single ionizing source and inconsistent with the binary interpretation.

  13. Chromatographic and computational assessment of lipophilicity using sum of ranking differences and generalized pair-correlation.

    PubMed

    Andrić, Filip; Héberger, Károly

    2015-02-06

    Lipophilicity (logP) represents one of the most studied and most frequently used fundamental physicochemical properties. At present there are several possibilities for its quantitative expression and many of them stems from chromatographic experiments. Numerous attempts have been made to compare different computational methods, chromatographic methods vs. computational approaches, as well as chromatographic methods and direct shake-flask procedure without definite results or these findings are not accepted generally. In the present work numerous chromatographically derived lipophilicity measures in combination with diverse computational methods were ranked and clustered using the novel variable discrimination and ranking approaches based on the sum of ranking differences and the generalized pair correlation method. Available literature logP data measured on HILIC, and classical reversed-phase combining different classes of compounds have been compared with most frequently used multivariate data analysis techniques (principal component and hierarchical cluster analysis) as well as with the conclusions in the original sources. Chromatographic lipophilicity measures obtained under typical reversed-phase conditions outperform the majority of computationally estimated logPs. Oppositely, in the case of HILIC none of the many proposed chromatographic indices overcomes any of the computationally assessed logPs. Only two of them (logkmin and kmin) may be selected as recommended chromatographic lipophilicity measures. Both ranking approaches, sum of ranking differences and generalized pair correlation method, although based on different backgrounds, provides highly similar variable ordering and grouping leading to the same conclusions.

  14. Peak-flow frequency relations and evaluation of the peak-flow gaging network in Nebraska

    USGS Publications Warehouse

    Soenksen, Philip J.; Miller, Lisa D.; Sharpe, Jennifer B.; Watton, Jason R.

    1999-01-01

    Estimates of peak-flow magnitude and frequency are required for the efficient design of structures that convey flood flows or occupy floodways, such as bridges, culverts, and roads. The U.S. Geological Survey, in cooperation with the Nebraska Department of Roads, conducted a study to update peak-flow frequency analyses for selected streamflow-gaging stations, develop a new set of peak-flow frequency relations for ungaged streams, and evaluate the peak-flow gaging-station network for Nebraska. Data from stations located in or within about 50 miles of Nebraska were analyzed using guidelines of the Interagency Advisory Committee on Water Data in Bulletin 17B. New generalized skew relations were developed for use in frequency analyses of unregulated streams. Thirty-three drainage-basin characteristics related to morphology, soils, and precipitation were quantified using a geographic information system, related computer programs, and digital spatial data.For unregulated streams, eight sets of regional regression equations relating drainage-basin to peak-flow characteristics were developed for seven regions of the state using a generalized least squares procedure. Two sets of regional peak-flow frequency equations were developed for basins with average soil permeability greater than 4 inches per hour, and six sets of equations were developed for specific geographic areas, usually based on drainage-basin boundaries. Standard errors of estimate for the 100-year frequency equations (1percent probability) ranged from 12.1 to 63.8 percent. For regulated reaches of nine streams, graphs of peak flow for standard frequencies and distance upstream of the mouth were estimated.The regional networks of streamflow-gaging stations on unregulated streams were analyzed to evaluate how additional data might affect the average sampling errors of the newly developed peak-flow equations for the 100-year frequency occurrence. Results indicated that data from new stations, rather than more

  15. Evaluation of the Influence of Sulfur-Fumigated Paeoniae Radix Alba on the Quality of Si Wu Tang by Chromatographic and Chemometric Analysis

    PubMed Central

    Pei, Ke; Duan, Yu; Qiao, Feng-Xian; Tu, Si-Cong; Liu, Xiao; Wang, Xiao-Li; Song, Xiao-Qing; Fan, Kai-Lei; Cai, Bao-Chang

    2016-01-01

    An accurate and reliable method of high-performance liquid chromatographic fingerprint combining with multi-ingredient determination was developed and validated to evaluate the influence of sulfur-fumigated Paeoniae Radix Alba on the quality and chemical constituents of Si Wu Tang. Multivariate data analysis including hierarchical cluster analysis and principal component analysis, which integrated with high-performance liquid chromatographic fingerprint and multi-ingredient determination, was employed to evaluate Si Wu Tang in a more objective and scientific way. Interestingly, in this paper, a total of 37 and 36 peaks were marked as common peaks in ten batches of Si Wu Tang containing sun-dried Paeoniae Radix Alba and ten batches of Si Wu Tang containing sulfur-fumigated Paeoniae Radix Alba, respectively, which indicated the changed fingerprint profile of Si Wu Tang when containing sulfur-fumigated herb. Furthermore, the results of simultaneous determination for multiple ingredients showed that the contents of albiflorin and paeoniflorin decreased significantly (P < 0.01) and the contents of gallic acid and Z-ligustilide decreased to some extent at the same time when Si Wu Tang contained sulfur-fumigated Paeoniae Radix Alba. Therefore, sulfur-fumigation processing may have great influence on the quality of Chinese herbal prescription. PMID:27034892

  16. The Huygens Gas Chromatograph Mass Spectrometer Investigation Of Titan

    NASA Astrophysics Data System (ADS)

    Atreya, Sushil; Harpold, Dan; Owen, Tobias

    2015-04-01

    A decade ago, on 14 January 2005, the Huygens probe of the Cassini-Huygens mission descended through the smog filled atmosphere of Titan and landed on the surface, revealing for the first time the extraordinary nature of Saturn's largest moon. One of the six payload instruments, the gas chromatograph mass spectrometer (GCMS), was crucial for measuring the composition of the atmosphere and the surface of Titan [1,2]. Most of the GCMS findings were "firsts", including the first direct identification of molecular nitrogen as the bulk constituent of the atmosphere, first vertical profile of Titan's second most abundant volatile, methane, first determination of primordial and radiogenic argon, first quantification of a number of stable gas isotopes, and the first measurements of the make-up of Titan's surface. These data are key to understanding why Titan is so unique amongst planetary moons in possessing a massive atmosphere [3], how Titan maintains a cycle of methane complete with surface reservoirs, evaporation and condensation like the hydrological cycle on earth [3,4,5], and what is responsible for the photochemical smog on Titan that plays a central role in the very existence of an atmosphere on Titan [3]. This presentation will discuss the GCMS investigation and how it helped shape our current view of Titan. [website for downloading pdf's of relevant papers: www.umich.edu/~atreya] [1] Niemann, H. B. et al., The abundances of constituents of Titan's atmosphere from the GCMS instrument on the Huygens probe, Nature 438, 779-784, 2005. [2] Niemann, H. B. et al., The composition of Titan's lower atmosphere and simple surface volatiles as measured by the Cassini-Huygens probe gas chromatograph mass spectrometer experiment, J. Geophys. Res. (Planets) 115, 12006, 2010. [3] Atreya S. K., R. D. Lorenz and J. H. Waite, Volatile origin and cycles: Nitrogen and methane, in Titan from Cassini-Huygens, R. H. Brown, J. P. Lebreton and J. Waite, (eds.), Springer Dordrecht

  17. Impacts of rising air temperatures on electric transmission ampacity and peak electricity load in the United States

    NASA Astrophysics Data System (ADS)

    Bartos, Matthew; Chester, Mikhail; Johnson, Nathan; Gorman, Brandon; Eisenberg, Daniel; Linkov, Igor; Bates, Matthew

    2016-11-01

    Climate change may constrain future electricity supply adequacy by reducing electric transmission capacity and increasing electricity demand. The carrying capacity of electric power cables decreases as ambient air temperatures rise; similarly, during the summer peak period, electricity loads typically increase with hotter air temperatures due to increased air conditioning usage. As atmospheric carbon concentrations increase, higher ambient air temperatures may strain power infrastructure by simultaneously reducing transmission capacity and increasing peak electricity load. We estimate the impacts of rising ambient air temperatures on electric transmission ampacity and peak per-capita electricity load for 121 planning areas in the United States using downscaled global climate model projections. Together, these planning areas account for roughly 80% of current peak summertime load. We estimate climate-attributable capacity reductions to transmission lines by constructing thermal models of representative conductors, then forcing these models with future temperature projections to determine the percent change in rated ampacity. Next, we assess the impact of climate change on electricity load by using historical relationships between ambient temperature and utility-scale summertime peak load to estimate the extent to which climate change will incur additional peak load increases. We find that by mid-century (2040-2060), increases in ambient air temperature may reduce average summertime transmission capacity by 1.9%-5.8% relative to the 1990-2010 reference period. At the same time, peak per-capita summertime loads may rise by 4.2%-15% on average due to increases in ambient air temperature. In the absence of energy efficiency gains, demand-side management programs and transmission infrastructure upgrades, these load increases have the potential to upset current assumptions about future electricity supply adequacy.

  18. Pharmacokinetics of mitomycin C in dogs: application of a high-performance liquid chromatographic assay.

    PubMed

    Barbhaiya, R H; Papp, E A; Van Harken, D R; Smyth, R D

    1984-09-01

    A normal-phase high-performance liquid chromatographic (HPLC) assay was developed for the determination of mitomycin C in plasma and urine. The method involves extraction of mitomycin C from plasma or urine into ethyl acetate-2-propanol-chloroform (70:15:15) with UV detection at 365 nm. Quantitation was performed with an internal standard (porfiromycin) by the peak height ratio method. Excellent correlation was obtained between the HPLC assay and the established microbiological cup-plate bioassay. The pharmacokinetics of mitomycin C were investigated in beagle dogs following a 1-mg/kg iv (22-mg/m2) bolus dose. The plasma mitomycin C concentration versus time data were analyzed by using an open three-compartment model. The average volume of distribution was 1.90 L or 17% of body weight for the central compartment and 7.7 L or 68% of body weight for the terminal elimination phase. The volumes of distribution at steady state, calculated by model-dependent and -independent methods, compared very well with each other and were 6.5 L or 58% of body weight. Total body clearance averaged 112 mL/min, and the mean terminal plasma half-life was 53 min. The 0-24-h urinary excretion of intact mitomycin C accounted for 19% of the dose. The terminal half-life and percent urinary recovery of mitomycin C in dogs is similar to that in humans. Based on these observations, the dog appears to be a good model for studying the disposition of mitomycin C.

  19. Stability-indicating high-performance liquid chromatographic assay of busulfan in aqueous and plasma samples.

    PubMed

    Chow, D S; Bhagwatwar, H P; Phadungpojna, S; Andersson, B S

    1997-12-19

    A sensitive, specific and stability-indicating high-performance liquid chromatographic (HPLC) assay, involving pre-column derivatization and solid-phase extraction (SPE), was developed and validated for the quantitation of busulfan (BU) in aqueous and plasma samples. The linearity of the assay was in the concentration ranges of 0.15-10 microg/ml and 0.15-3 microg/ml for aqueous and plasma samples, respectively. The within-day and between-day variations were 2.90 and 3.31%, respectively, for the aqueous samples, and 9.24 and 14.56%, respectively, for the plasma samples. The overall recovery, derivatization yield and SPE efficiency of BU from plasma samples were 82.03, 108.01 and 86.69%, respectively. Forced degraded samples, either in highly acidic, neutral or basic medium, produced no interfering peaks in the chromatogram. The reported assay requires only 0.2 ml of plasma for the analysis, and its sensitivity is 150 ng/ml by monitoring samples at a wavelength of 254 nm, sufficient to study the plasma pharmacokinetics of BU in rats after a clinically relevant oral dose. Moreover, the sensitivity of the assay can be significantly increased to 30 ng/ml by monitoring samples at a wavelength of 278 nm. The applications of the assay were demonstrated with BU solubility measurements in two aqueous systems and with plasma samples from a Sprague-Dawley rat for an in vivo pharmacokinetic study. In addition, the assay has been employed in the development of a patented intravenous formulation, and in evaluations of stability, preclinical pharmacokinetics in rats and dogs, and clinical phase I trial of the formulation. The assay is readily adaptable to clinical therapeutic drug monitoring.

  20. A method for the analysis of tabun in multisol using gas chromatographic flame photometric detection.

    PubMed

    Logan, Thomas P; Allen, Edward D; Way, Mark R; Swift, Austin T; Soni, Sunil-Datta; Koplovitz, Irwin

    2006-01-01

    Preparation and analysis of tabun (GA) solutions are necessary for the continued development of countermeasures to this nerve agent. GA solutions must be stable and compatible for use in the test systems chosen for study; however, GA is very unstable in saline solutions. In the past we have found GA in saline at 2 mg/mL to be stable for a month or less at -70 degrees C, whereas saline solutions of sarin (GB), soman (GD), and cyclosarin (GF) were stable for many months. Previous studies have shown that Multisol (48.5% H(2)O, 40% propylene glycol, 10% ethanol, and 1.5% benzyl alcohol) provides stable solutions of GA. We confirmed the stability of GA in Multisol with phosphorus nuclear magnetic resonance (P horizontal line NMR) and developed a method for the analysis of GA in Multisol using gas chromatographic flame photometric detection (GCFPD) in the phosphorus mode. The GC method used acetonitrile (CH(3)CN) for a dilution solvent because of its miscibility with GA in chloroform (CHCl(3)) standards and GA in Multisol samples at 1% (v/v). Furthermore, the dilutions with CH(3)CN made the phosphorus mode interference peak present in CHCl(3) analytically manageable, reduced the interferences of Multisol in the GC separation, and contributed to a safe and reliable analysis of GA at 20 mug/mL. We demonstrated the stability of GA in Multisol stored for more than a year at 70 degrees C. This method contributes a suitable technique for the preparation and analysis of reliable solutions of GA in nerve agent medical research and demonstrates the extended stability of GA in Multisol.

  1. Liquid chromatographic determination of para-toluenesulfonamide in edible fillet tissues from three species of fish

    USGS Publications Warehouse

    Meinertz, J.R.; Schmidt, L.J.; Stehly, G.R.; Gingerich, W.H.

    1999-01-01

    Chloramine-T (N-sodium-N-chloro-p-toluene-sulfonamide) is a candidate therapeutic drug for treating bacterial gill disease, a predominant disease of a variety of fish species. Research has been initiated to obtain the U.S. Food and Drug Administration's (FDA) approval for the use of chloramine-T on a variety of fish species. An attribute of a therapeutic aquaculture drug that must be characterized before the FDA approves its use is depletion of the drug's marker residue (the drug's parent compound or metabolite of highest concentration in an edible tissue). Para-Toluenesulfonamide (p-TSA) is the primary degradation product and marker residue for chloramine-T in rainbow trout. To conduct residue depletion studies for chloramine-T in fish, a robust analytical method sensitive and specific for p-TSA residues in edible fillet tissue from a variety of fish was required. Homogenized fillet tissues from rainbow trout (Oncorhynchus mykiss), walleye (Stizostedion vitreum), and channel catfish (Ictalurus punctatus) were fortified at nominal p-TSA concentrations of 17, 67, 200, 333, and 1000 ng/g. Samples were analyzed by isocratic reversed-phase liquid chromatography (LC) with absorbance detection at 226 nm. Mean recoveries of p-TSA ranged from 77 to 93.17%; relative standard deviations ranged from 1.5 to 14%; method quantitation limits ranged from 13 to 18 ng/g; and method detection limits ranged from 3.8 to 5.2 ng/g. The LC parameters produced p-TSA peaks without coelution of endogenous compounds and excluded chromatographic interference from at least 20 chemicals and drugs of potential use in aquaculture.

  2. Rapid, fluorimetric-liquid chromatographic determination of malondialdehyde in biological samples.

    PubMed

    Agarwal, Rajiv; Chase, Shawn D

    2002-07-25

    Current chromatographic methods of estimation of malondialdehyde, a marker of oxidative lipid injury, often require extensive extraction procedures, column cleaning or specialized equipment. A rapid and sensitive HPLC method is described for the determination of MDA in plasma and urine. The mobile phase consisted of 40:60 ratio (v/v) of methanol to 50 mM potassium monobasic phosphate at pH 6.8, pumped at a rate of 1.0 ml/min on a Hewlett-Packard Hypersil 5 micro ODS 100 x 4.6 mm placed in a column warmer set to 37 degrees C. Samples of plasma and urine were treated with the antioxidant, butylated hydroxytoluene and heat derivatized at 100 degrees C for 1 h with thiobarbituric acid at an acid pH. Samples were extracted with n-butanol and 10 microl of the extract was injected at 1 min intervals using an autosampler. The Hewlett-Packard model 1046A programmable fluorescence detector was set at excitation of 515 nm and emission of 553 nm. Retention time was 1.87 min, however absence of interfering peaks, allowed analysis to be carried out in increments of 1 min per sample. Within day variability in estimation was between 8.6% and 10.3%. Between days variability was 3.6-7.9%. Recovery was between 88 and 101%. Samples of urine and plasma from ten normotensive volunteers were 1.94 +/- 0.79 micromol/g creatinine and 0.69 +/- 0.13 micromol/l respectively and were similar to those reported in the literature. MDA degrades at room temperature at a rate of 10% per hour. It is therefore, suggested that the total assay time be limited to 1 h beginning with sample preparation.

  3. Comprehensive two-dimensional gas chromatographic separations with a microfabricated thermal modulator.

    PubMed

    Serrano, Gustavo; Paul, Dibyadeep; Kim, Sung-Jin; Kurabayashi, Katsuo; Zellers, Edward T

    2012-08-21

    Rapid, comprehensive two-dimensional gas chromatographic (GC × GC) separations by use of a microfabricated midpoint thermal modulator (μTM) are demonstrated, and the effects of various μTM design and operating parameters on performance are characterized. The two-stage μTM chip consists of two interconnected spiral etched-Si microchannels (4.2 and 2.8 cm long) with a cross section of 250 × 140 μm(2), an anodically bonded Pyrex cap, and a cross-linked wall coating of poly(dimethylsiloxane) (PDMS). Integrated heaters provide rapid, sequential heating of each μTM stage, while a proximate, underlying thermoelectric cooler provides continual cooling. The first-dimension column used for GC × GC separations was a 6 m long, 250 μm i.d. capillary with a PDMS stationary phase, and the second-dimension column was a 0.5 m long, 100 μm i.d. capillary with a poly(ethylene glycol) phase. Using sets of five to seven volatile test compounds (boiling point ≤174 °C), the effects of the minimum (T(min)) and maximum (T(max)) modulation temperature, stage heating lag/offset (O(s)), modulation period (P(M)), and volumetric flow rate (F) on the quality of the separations were evaluated with respect to several performance metrics. Best results were obtained with a T(min) = -20 °C, T(max) = 210 °C, O(s) = 600 ms, P(M) = 6 s, and F = 0.9 mL/min. Replicate modulated peak areas and retention times were reproducible to <5%. A structured nine-component GC × GC chromatogram was produced, and a 21 component separation was achieved in <3 min. The potential for creating portable μGC × μGC systems is discussed.

  4. Determination of mercurial species in fish by inductively coupled plasma mass spectrometry with anion exchange chromatographic separation.

    PubMed

    Chen, Xiaopan; Han, Chao; Cheng, Heyong; Liu, Jinhua; Xu, Zigang; Yin, Xuefeng

    2013-09-24

    This work demonstrated the feasibility of mercury speciation analysis by anion exchange chromatographic separation with inductively coupled plasma mass spectrometry detection. For the first time, by complexing with the mobile phase containing 3-mercapto-1-propanesulfonate into negatively charged complexes, fast separation of inorganic mercury (Hg(2+)), monomethylmercury (MeHg), ethylmercury (EtHg) and phenylmercury (PhHg) was achieved within 5 min on a 12.5-mm strong anion exchange column. The detection limits for Hg(2+), MeHg, EtHg and PhHg were 0.008, 0.024, 0.029 and 0.034 μg L(-1), respectively. The relative standard deviations of peak height and peak area (5.0 μg L(-1) for each Hg species) were all below 3%. The determined contents of Hg(2+), MeHg and total Hg in a certified reference material of fish tissue by the proposed method were in good accordance with the certified values with satisfactory recoveries. The relative errors for determining MeHg and total mercury were -2.4% and -1.2%, respectively, with an acceptable range for spike recoveries of 94-101%. Mercury speciation in 11 fish samples were then analyzed after the pretreated procedure. The mercury contents in all fish samples analyzed were found compliant with the criteria of the National Standards of China.

  5. Chromatographic fingerprint analysis and simultaneous determination of eight lignans in Justicia procumbens and its compound preparation by HPLC-DAD.

    PubMed

    Wang, Linan; Pan, Jianyu; Yang, Meihua; Wu, Jun; Yang, Junshan

    2011-03-01

    HPLC fingerprints were developed for the quality evaluation of Justicia procumbens and its compound preparation, Jian-er syrup, together with the simultaneous quantification of eight arylnaphthalide lignans (6'-hydroxy justicidin B, 6'-hydroxy justicidin A, 6'-hydroxy justicidin C, justicidin B, chinensinaphthol methyl ether, justicidin C, taiwanin C, and neojusticin A). Samples were separated with a Shiseido Capcell Pak C(18) reversed-phase column (250×4.6 mm id, 5 μm) using acetonitrile and water as the mobile phase. The column temperature was maintained at 35°C and the wavelength of detector was set at 256 nm. For fingerprint analysis, 17 peaks were selected as the characteristic peaks for the evaluation of the similarities among different J. procumbens samples collected in different places. The structures of lignans were confirmed by diagnostic fragments in the positive ESI-MS(n) . The new method was successfully applied for the chromatographic fingerprint analysis and simultaneous determination of eight lignans in its compound preparation, Jian-er syrup. All the results indicated that HPLC fingerprint assay in combination with multi-marker determination afforded a useful method for the quality control of J. procumbens and its compound preparation, Jian-er syrup.

  6. Post-synthetic modification of MIL-101(Cr) with pyridine for high-performance liquid chromatographic separation of tocopherols.

    PubMed

    Yang, Fang; Yang, Cheng-Xiong; Yan, Xiu-Ping

    2015-05-01

    Effective separation of tocopherols is challenging and significant due to their structural similarity and important biological role. Here we report the post-synthetic modification of metal-organic framework (MOF) MIL-101(Cr) with pyridine for high-performance liquid chromatographic (HPLC) separation of tocopherols. Baseline separation of four tocopherols was achieved on a pyridine-grafted MIL-101(Cr) packed column within 10 min using hexane/isopropanol (96:4, v/v) as the mobile phase at a flow rate of 0.5 mL min(-1). The pyridine-grafted MIL-101(Cr) packed column gave high column efficiency (85,000 plates m(-1) for δ-tocopherol) and good precision (0.2-0.3% for retention time, 1.8-3.4% for peak area, 2.6-2.7% for peak height), and also offered much better performance than unmodified MIL-101(Cr) and commercial amino-bonded silica packed column for HPLC separation of tocopherols. The results not only show the promising application of pyridine-grafted MIL-101(Cr) as a novel stationary phase for HPLC separation of tocopherols, but also reveal a facile post-modification of MOFs to expand the application of MOFs in separation sciences.

  7. Combining hypoxic methods for peak performance.

    PubMed

    Millet, Gregoire P; Roels, B; Schmitt, L; Woorons, X; Richalet, J P

    2010-01-01

    New methods and devices for pursuing performance enhancement through altitude training were developed in Scandinavia and the USA in the early 1990s. At present, several forms of hypoxic training and/or altitude exposure exist: traditional 'live high-train high' (LHTH), contemporary 'live high-train low' (LHTL), intermittent hypoxic exposure during rest (IHE) and intermittent hypoxic exposure during continuous session (IHT). Although substantial differences exist between these methods of hypoxic training and/or exposure, all have the same goal: to induce an improvement in athletic performance at sea level. They are also used for preparation for competition at altitude and/or for the acclimatization of mountaineers. The underlying mechanisms behind the effects of hypoxic training are widely debated. Although the popular view is that altitude training may lead to an increase in haematological capacity, this may not be the main, or the only, factor involved in the improvement of performance. Other central (such as ventilatory, haemodynamic or neural adaptation) or peripheral (such as muscle buffering capacity or economy) factors play an important role. LHTL was shown to be an efficient method. The optimal altitude for living high has been defined as being 2200-2500 m to provide an optimal erythropoietic effect and up to 3100 m for non-haematological parameters. The optimal duration at altitude appears to be 4 weeks for inducing accelerated erythropoiesis whereas <3 weeks (i.e. 18 days) are long enough for beneficial changes in economy, muscle buffering capacity, the hypoxic ventilatory response or Na(+)/K(+)-ATPase activity. One critical point is the daily dose of altitude. A natural altitude of 2500 m for 20-22 h/day (in fact, travelling down to the valley only for training) appears sufficient to increase erythropoiesis and improve sea-level performance. 'Longer is better' as regards haematological changes since additional benefits have been shown as hypoxic exposure

  8. Peak phosphorus - peak food? The need to close the phosphorus cycle.

    PubMed

    Rhodes, Christopher J

    2013-01-01

    The peak in the world production of phosphorus has been predicted to occur in 2033, based on world reserves of rock phosphate (URR) reckoned at around 24,000 million tonnes (Mt), with around 18,000 Mt remaining. This figure was reckoned-up to 71,000 Mt, by the USGS, in 2012, but a production maximum during the present century is still highly probable. There are complex issues over what the demand will be for phosphorus in the future, as measured against a rising population (from 7 billion to over 9 billion in 2050), and a greater per capita demand for fertiliser to grow more grain, in part to feed animals and meet a rising demand for meat by a human species that is not merely more populous but more affluent. As a counterweight to this, we may expect that greater efficiencies in the use of phosphorus - including recycling from farms and of human and animal waste - will reduce the per capita demand for phosphate rock. The unseen game changer is peak oil, since phosphate is mined and recovered using machinery powered by liquid fuels refined from crude oil. Hence, peak oil and peak phosphorus might appear as conjoined twins. There is no unequivocal case that we can afford to ignore the likelihood of a supply-demand gap for phosphorus occurring sometime this century, and it would be perilous to do so.

  9. Can You Hear That Peak? Utilization of Auditory and Visual Feedback at Peak Limb Velocity

    ERIC Educational Resources Information Center

    Loria, Tristan; de Grosbois, John; Tremblay, Luc

    2016-01-01

    Purpose: At rest, the central nervous system combines and integrates multisensory cues to yield an optimal percept. When engaging in action, the relative weighing of sensory modalities has been shown to be altered. Because the timing of peak velocity is the critical moment in some goal-directed movements (e.g., overarm throwing), the current study…

  10. Endurance running program reverses the age related declines in peak oxygen consumption

    SciTech Connect

    Cartee, G.D.; Farrar, R.P.

    1986-03-01

    This study was designed to determine whether aging per se produces a decline in peak oxygen consumption (peak VO/sub 2/) or whether that decline may be due to the documented reduction in spontaneous activity. Male F344 rats, at the initial ages of 4 and 18 mos. of age, were divided into trained and untrained groups (YUT, YT, OUT, and OT). The trained groups ran up to 60 min/day 5 days/wk at a speed of 20m/min for 6 mos. The OUT rats demonstrated a 12% decline in peak VO/sub 2/ when compared to YUT rats. The OT rats had the same peak VO/sub 2/ as the YUT, but a 13% lower peak VO/sub 2/ than the YT. Representative enzymes of the TCA cycle, B oxidation, and electron transport system from gastrocnemius homogenates all declined in the OUT compared to YUT (14 to 24%). /sup 14/C-palmitate oxidation declined 45% in the OUT gastrocnemius compared to YUT. The carnitine values of the OUT were not significantly lower than the YUT and could not account for the large depression in palmitate oxidation. In contrast to the peak VO/sub 2/ which increased in OT only up to YUT values, the oxidative capacity of the skeletal muscle of OT was increased above the YUT group values equal to those of YT.

  11. Lander petal & Twin Peaks - 3D

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Many prominent rocks near the Sagan Memorial Station are featured in this image, taken in stereo by the Imager for Mars Pathfinder (IMP) on Sol 3. 3D glasses are necessary to identify surface detail. The two hills in the distance, approximately one to two kilometers away, have been dubbed the 'Twin Peaks' and are of great interest to Pathfinder scientists as objects of future study. The white areas on the left hill, called the 'Ski Run' by scientists, may have been formed by hydrologic processes. A lander petal, airbag, and the rear ramp are at the lower area of the image.

    The image was taken by the Imager for Mars Pathfinder (IMP) after its deployment on Sol 3. Mars Pathfinder was developed and managed by the Jet Propulsion Laboratory (JPL) for the National Aeronautics and Space Administration. The IMP was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

    Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right

  12. NOx control buys to peak in `98

    SciTech Connect

    McIlvaine, R.W.

    1995-10-01

    Titles I and IV of the Clean Air Act provide the legislative framework for a huge NOx reduction program now in operation. This reduction will have a substantial effect in reducing ground-level ozone. A new McIlvaine report concludes that US utilities and industrial companies during the next 10 years will spend more than $800 million annually to meet CAA`s NOx-control regulations. Much of that investment will be for low-NOx burners, which minimize NOx formation. Many utilities and industrial boilers can be retrofitted with a new generation of burners; however, this technology achieves less than 50% NOx reduction. Post-combustion technologies, such as selective catalytic reduction and selective noncatalytic reduction, can reduce NOx as much as 90%. Therefore, plants needing greater NOx reduction will use post-combustion technologies, often in combination with low-NOx burners. The peak order year for NOx-control equipment will be 1998, primarily because Title IV of CAA requires utilities to comply by 2000. Many industrial sources also will be ordering equipment in 1998.

  13. North Twin Peak in super resolution

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This pair of images shows the result of taking a sequence of 25 identical exposures from the Imager for Mars Pathfinder (IMP) of the northern Twin Peak, with small camera motions, and processing them with the Super-Resolution algorithm developed at NASA's Ames Research Center.

    The upper image is a representative input image, scaled up by a factor of five, with the pixel edges smoothed out for a fair comparison. The lower image allows significantly finer detail to be resolved.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

    The super-resolution research was conducted by Peter Cheeseman, Bob Kanefsky, Robin Hanson, and John Stutz of NASA's Ames Research Center, Mountain View, CA. More information on this technology is available on the Ames Super Resolution home page at

    http://ic-www.arc.nasa.gov/ic/projects/bayes-group/ group/super-res/

  14. Acetone as a greener alternative to acetonitrile in liquid chromatographic fingerprinting.

    PubMed

    Funari, Cristiano Soleo; Carneiro, Renato Lajarim; Khandagale, Manish M; Cavalheiro, Alberto José; Hilder, Emily F

    2015-05-01

    A considerable amount of chemical waste from liquid chromatography analysis is generated worldwide. Acetonitrile is the most employed solvent in liquid chromatography analyses since it exhibits favorable physicochemical properties for separation and detection, but it is an unwelcome solvent from an environmental point of view. Acetone might be a much greener alternative to replace acetonitrile in reversed-phase liquid chromatography, since both share similar physicochemical properties, but its applicability with ultraviolet absorbance-based detectors is limited. In this work, a reference method using acetonitrile and high-performance liquid chromatography coupled to an ultraviolet photodiode array detector coupled to a corona charged aerosol detector system was developed to fingerprint a complex sample. The possibility of effectively substituting acetonitrile with acetone was investigated. Design of experiments was adopted to maximize the number of peaks acquired in both fingerprint developments. The methods with acetonitrile or acetone were successfully optimized and proved to be statistically similar when only the number of peaks or peak capacity was taken into consideration. However, the superiority of the latter was evidenced when parameters of separation and those related to greenness were heuristically combined. A green, comprehensive, time- and resource-saving approach is presented here, which is generic and applicable to other complex matrices. Furthermore, it is in line with environmental legislation and analytical trends.

  15. Micro-miniature gas chromatograph column disposed in silicon wafers

    DOEpatents

    Yu, Conrad M.

    2000-01-01

    A micro-miniature gas chromatograph column is fabricated by forming matching halves of a circular cross-section spiral microcapillary in two silicon wafers and then bonding the two wafers together using visual or physical alignment methods. Heating wires are deposited on the outside surfaces of each wafer in a spiral or serpentine pattern large enough in area to cover the whole microcapillary area inside the joined wafers. The visual alignment method includes etching through an alignment window in one wafer and a precision-matching alignment target in the other wafer. The two wafers are then bonded together using the window and target. The physical alignment methods include etching through vertical alignment holes in both wafers and then using pins or posts through corresponding vertical alignment holes to force precision alignment during bonding. The pins or posts may be withdrawn after curing of the bond. Once the wafers are bonded together, a solid phase of very pure silicone is injected in a solution of very pure chloroform into one end of the microcapillary. The chloroform lowers the viscosity of the silicone enough that a high pressure hypodermic needle with a thumbscrew plunger can force the solution into the whole length of the spiral microcapillary. The chloroform is then evaporated out slowly to leave the silicone behind in a deposit.

  16. Authenticity analysis of pear juice employing chromatographic fingerprinting.

    PubMed

    Willems, Jamie L; Low, Nicholas H

    2014-12-03

    Pear juice is predominately composed of carbohydrates/polyols (>95% of the total soluble solids), making it susceptible to adulteration by the addition of less expensive commercial sweeteners. In this research, the major carbohydrate and polyol (fructose, glucose, sucrose, and sorbitol) content of 32 pure pear juices representing five world producing regions and three years of production was determined. Additionally, methods employing oligosaccharide profiling to detect the debasing of these samples with four commercial sweeteners (HFCS 55 and 90, TIS, and HIS) were developed using capillary gas chromatography with flame ionization detection (CGC-FID) and high-performance liquid chromatography with pulsed amperometric detection (HPAE-PAD). Detection limits for the four commercial sweeteners ranged from 0.5 to 5.0% (v/v). In addition, the developed CGC-FID method could be used to (a) detect the addition of pear to apple juice via arbutin detection and (b) determine if a pear juice was produced using enzymatic liquefaction via the presence of O-β-d-glucopyranosyl-(1→4)-d-glucopyranose (cellobiose), all within a single chromatographic analysis.

  17. Liquid chromatographic determination of progestogens in animal fat.

    PubMed

    Andresen, M T; Fesser, A C

    1996-01-01

    A liquid chromatographic method was developed for determination of 3 progestogens-melengestrol acetate, megestrol acetate, and chlormadinone acetate-found in edible tissue at concentrations between 10 and 1000 ppb. These progestogens are commonly used as feed additives to control herd estrus and to improve feed efficiency. Rendered fat was extracted with acetonitrile, washed with hexane, and dried. The remaining lipids were saponified with sodium hydroxide and precipitated with magnesium chloride. The progestogens were extracted from the basic solution with hexane, dried, and cleaned up on a cyanopropyl solid-phase extraction column in the normal-phase mode. The eluate was dried and reconstituted with acetonitrile-water (7 + 3, v/v). Chromatography was performed on a 5 microns high-carbon load C18 column with acetonitrile-water (7 + 3, v/v) at 1 mL/min and UV detection at 291 nm. Recoveries from fortified samples ranged from 84 to 116%. The limit of quantitation was 10 ppb for both beef and pork. The detection limit was 3 ppb.

  18. Liquid chromatographic analysis of oxytocin and its related substances.

    PubMed

    Ashenafi, Dunge; Van Hemelrijck, Elise; Chopra, Shruti; Hoogmartens, Jos; Adams, Erwin

    2010-01-05

    A selective gradient liquid chromatographic (LC) method for the determination of oxytocin (OT) and its related substances in bulk drugs has been developed. The method uses a reversed-phase C18 column (25 cm x 4.0 mm i.d.), 5 microm kept at 40 degrees C. The mobile phases consist of acetonitrile, dihydrogen phosphate solution pH 4.4 and water. The flow rate is 1.0 ml/min. UV detection is performed at 220 nm. A system suitability test (SST) was developed to govern the quality of the separation. The separation towards OT components was investigated on different C18 columns. The developed method was further validated with respect to robustness, precision, sensitivity and linearity. A central composite design was applied to examine the robustness of the method. The method shows good precision, sensitivity, linearity and robustness. Two commercial OT samples were examined using this method. Furthermore, the method proved to be successful when applied to analyze a marketed OT formulation for injection.

  19. Chromatographic Studies of Protein-Based Chiral Separations.

    PubMed

    Bi, Cong; Zheng, Xiwei; Azaria, Shiden; Beeram, Sandya; Li, Zhao; Hage, David S

    2016-09-01

    The development of separation methods for the analysis and resolution of chiral drugs and solutes has been an area of ongoing interest in pharmaceutical research. The use of proteins as chiral binding agents in high-performance liquid chromatography (HPLC) has been an approach that has received particular attention in such work. This report provides an overview of proteins that have been used as binding agents to create chiral stationary phases (CSPs) and in the use of chromatographic methods to study these materials and protein-based chiral separations. The supports and methods that have been employed to prepare protein-based CSPs will also be discussed and compared. Specific types of CSPs that are considered include those that employ serum transport proteins (e.g., human serum albumin, bovine serum albumin, and alpha1-acid glycoprotein), enzymes (e.g., penicillin G acylase, cellobiohydrolases, and α-chymotrypsin) or other types of proteins (e.g., ovomucoid, antibodies, and avidin or streptavidin). The properties and applications for each type of protein and CSP will also be discussed in terms of their use in chromatography and chiral separations.

  20. Capillary gas chromatographic analysis of pans with luminol chemilumnescent detection

    SciTech Connect

    Gaffney, J.; Bornick, R.; Chen, Yu-Harn; Marley, N.

    1996-12-31

    Peroxyacyl nitrates (PANs) are important air pollutants in tropospheric chemistry. PANs are known to be potent phytotoxins at low ppb concentrations and are lachrymators. They can also transport the more reactive nitrogen dioxide long distances, because they are in equilibrium with that NO{sub x} species. Since PANs are trapped peroxyradicals, they are a direct measure of the peroxyradical levels and the of {open_quotes}photochemical age{close_quotes} of an air parcel. The PANs are typically measured in the atmosphere by using electron capture detection methods. These methods suffer from large background signals and detector responses to oxygen and water vapor. This paper describes the combination of a capillary gas chromatographic column with a modified luminol chemiluminescent nitrogen dioxide detector (Scintrex, Luminox) for rapid and sensitive detection of nitrogen dioxide, peroxyacetyl nitrate, peroxypropionyl nitrate, and peroxybutyryl nitrate. Detection limits for this approach in the low tens of parts per trillion have been observed with total analysis times of less than three minutes. We will discuss the potential application of this method to other compounds, particularly, organonitrates, in a pyrolysis system and/or with ozone addition to the sampling streams.

  1. Biphasic Affinity Chromatographic Approach for Deep Tyrosine Phosphoproteome Analysis.

    PubMed

    Deng, Zhenzhen; Dong, Mingming; Wang, Yan; Dong, Jing; Li, Shawn S-C; Zou, Hanfa; Ye, Mingliang

    2017-02-21

    Tyrosine phosphorylation (pTyr) is important for normal physiology and implicated in many human diseases, particularly cancer. Identification of pTyr sites is critical to dissecting signaling pathways and understanding disease pathologies. However, compared with serine/threonine phosphorylation (pSer/pThr), the analysis of pTyr at the proteome level is more challenging due to its low abundance. Here, we developed a biphasic affinity chromatographic approach where Src SH2 superbinder was coupled with NeutrAvidin affinity chromatography, for tyrosine phosphoproteome analysis. With the use of competitive elution agent biotin-pYEEI, this strategy can distinguish high-affinity phosphotyrosyl peptides from low-affinity ones, while the excess competitive agent is readily removed by using NeutrAvidin agarose resin in an integrated tip system. The excellent performance of this system was demonstrated by analyzing tyrosine phosphoproteome of Jurkat cells from which 3,480 unique pTyr sites were identified. The biphasic affinity chromatography method for deep Tyr phosphoproteome analysis is rapid, sensitive, robust, and cost-effective. It is widely applicable to the global analysis of the tyrosine phosphoproteome associated with tyrosine kinase signal transduction.

  2. Novel reduced pressure-balance syringe for chromatographic analysis.

    PubMed

    Windom, Bret C; Bruno, Thomas J

    2010-11-19

    When withdrawing a fluid sample (for additional chromatographic analyses) from an apparatus operated at a reduced pressure, a typical syringe proves to be ineffective (even if it is equipped with a gas tight plunger). It simply does not create enough pressure differential to remove a fluid sample from a reduced pressure environment. We encountered such a situation as part of efforts to extend the operation of the advanced distillation curve protocol to reduced pressures. The problem was solved by the development of a pressure balance syringe that allows reliable and precise sampling from an apparatus operating at sub-ambient pressures. This new device uses an external vacuum source to evacuate a syringe barrel, allowing a user to withdraw fluid samples from environments with pressures as low as 0.5kPa. To demonstrate the operation of the newly developed device, distillate analyses were performed on two fluids at low pressure: a predefined validation mixture, and a commercial soy based biodiesel fuel. The pressure balance syringe was used successfully for sampling in both cases. The use of the pressure balance syringe is not limited to reduced pressure distillations; indeed it can be used for a variety of applications in which chemical/compositional analyses are desired on a fluid contained in a reduced pressure environment.

  3. Liquid chromatographic determination of beta-naphthoxyacetic acid in tomatoes.

    PubMed

    Gökmen, V; Acar, J

    1998-03-06

    An alternative high-performance liquid chromatographic method for the determination of beta-naphthoxyacetic acid (BNOA) in tomatoes is described. BNOA was extracted from tomatoes with acetone-dichloromethane (2:1). The extract was cleaned up by Bio-Beads S-X3 gel-permeation chromatography and by partitioning. A reversed-phase C18 column was used for HPLC analysis. The mobile phase was acetonitrile-2% acetic acid in water (50:50, v/v) pumped at a flow-rate of 1.0 ml/min. Retention time of BNOA was ca. 7 min with a percentage coefficient of variation of 0.71. Resolution of BNOA was good on the column. Percentage recoveries of BNOA were 79.5 +/- 6.82, 94.8 +/- 2.70 and 86.4 +/- 16.43 for the corresponding spiking levels of 0.5, 1.0 and 2.0 micrograms per g tomato, respectively. Analysis of 10 greenhouse tomato samples from local markets in Ankara showed no BNOA residue.

  4. Recent Advances in Water Analysis with Gas Chromatograph Mass Spectrometers

    NASA Technical Reports Server (NTRS)

    MacAskill, John A.; Tsikata, Edem

    2014-01-01

    We report on progress made in developing a water sampling system for detection and analysis of volatile organic compounds in water with a gas chromatograph mass spectrometer (GCMS). Two approaches are described herein. The first approach uses a custom water pre-concentrator for performing trap and purge of VOCs from water. The second approach uses a custom micro-volume, split-splitless injector that is compatible with air and water. These water sampling systems will enable a single GC-based instrument to analyze air and water samples for VOC content. As reduced mass, volume, and power is crucial for long-duration, manned space-exploration, these water sampling systems will demonstrate the ability of a GCMS to monitor both air and water quality of the astronaut environment, thereby reducing the amount of required instrumentation for long duration habitation. Laboratory prototypes of these water sampling systems have been constructed and tested with a quadrupole ion trap mass spectrometer as well as a thermal conductivity detector. Presented herein are details of these water sampling system with preliminary test results.

  5. Chromatographic Studies of Protein-Based Chiral Separations

    PubMed Central

    Bi, Cong; Zheng, Xiwei; Azaria, Shiden; Beeram, Sandya; Li, Zhao; Hage, David S.

    2016-01-01

    The development of separation methods for the analysis and resolution of chiral drugs and solutes has been an area of ongoing interest in pharmaceutical research. The use of proteins as chiral binding agents in high-performance liquid chromatography (HPLC) has been an approach that has received particular attention in such work. This report provides an overview of proteins that have been used as binding agents to create chiral stationary phases (CSPs) and in the use of chromatographic methods to study these materials and protein-based chiral separations. The supports and methods that have been employed to prepare protein-based CSPs will also be discussed and compared. Specific types of CSPs that are considered include those that employ serum transport proteins (e.g., human serum albumin, bovine serum albumin, and alpha1-acid glycoprotein), enzymes (e.g., penicillin G acylase, cellobiohydrolases, and α-chymotrypsin) or other types of proteins (e.g., ovomucoid, antibodies, and avidin or streptavidin). The properties and applications for each type of protein and CSP will also be discussed in terms of their use in chromatography and chiral separations. PMID:28344977

  6. Characterisation of wax works of art by gas chromatographic procedures.

    PubMed

    Regert, M; Langlois, J; Colinart, S

    2005-10-14

    To identify the various natural and synthetic substances used by sculptors at the end of the 19th century, several contemporary reference samples were investigated by high temperature gas chromatography (HT GC) and HT GC-MS. Using specific chromatographic conditions and minimising sample preparation, we could separate, detect and identify a wide range of biomolecular markers covering a great variety of molecular weights and volatilities, with a minimum amount of sample, in a single run. Beeswax, spermaceti, carnauba, candellila and Japan waxes as well as pine resin derivatives, animal fats, paraffin, ozokerite and stearin, used as additives in wax works of art, were chemically investigated. In the case of low volatile compounds, transbutylation was performed. The structure of long-chain esters of spermaceti was elucidated for the first time by HT GC-MS analysis. Such a method was then carried out on 10 samples collected on a statuette of Junon by Antoine-Louis Barye (Louvre Museum, Paris, France) and on a sculpture by Aimé-Jules Dalou (Musée de la Révolution Française, Vizille, France). The analytical results obtained provide new data on the complex recipes elaborated by sculptors at the end of the 19th century.

  7. Comprehensive two-dimensional liquid chromatographic analysis of anthocyanins.

    PubMed

    Willemse, Chandré M; Stander, Maria A; Tredoux, Andreas G J; de Villiers, André

    2014-09-12

    Anthocyanins are naturally occurring plant pigments whose accurate analysis is hampered by their complexity and unique chromatographic behaviour associated with on-column conversion reactions. This paper reports the evaluation of off-line comprehensive two-dimensional liquid chromatography (LC×LC) for the analysis of anthocyanins. Hydrophilic interaction chromatography (HILIC) was used in the first dimension in combination with reversed phase liquid chromatography (RP-LC) in the second dimension. For the selective detection of anthocyanins, diode array detection was used, while high resolution quadrupole-time-of-flight mass spectrometry (Q-TOF) was used for compound identification. As application, the HILIC×RP-LC separation of diverse anthocyanins in blueberries, red radish, black beans, red grape skins and red cabbage is demonstrated. Off-line HILIC×RP-LC revealed information which could not be obtained by one-dimensional HPLC methods, while the structured elution order for the anthocyanins simplifies compound identification and facilitates the comparison of anthocyanin content of natural products by means of contour plots.

  8. Suspended particle and pathogen peak discharge buffering by a surface-flow constructed wetland.

    PubMed

    Mulling, Bram T M; van den Boomen, Rob M; van der Geest, Harm G; Kappelhof, Joost W N M; Admiraal, Wim

    2013-03-01

    Constructed wetlands (CWs) have been shown to improve the water quality of treated wastewater. The capacity of CWs to reduce nutrients, pathogens and organic matter and restore oxygen regime under normal operating conditions cannot be extrapolated to periods of incidental peak discharges. The buffering capacity of CWs during peak discharges is potentially a key factor for water quality in the receiving waters. Therefore, the aim of the present study was to investigate the behaviour of peak discharges of suspended particles, (associated) physiochemical parameters and pathogenic organisms from a wastewater treatment plant (WWTP) in a full scale constructed wetland (CW). By mixing clarified water and sludge rich water from the settlement tank of the WWTP, the suspended particle concentration was increased for 8 h from ± 3.5 to ± 230 mg L(-1), and discharged into a full scale horizontal surface flow constructed wetland. An increase of suspended particle concentration following the peak discharge concurred with increases in turbidity and oxygen demand, total nutrient load (nitrogen, phosphorus and carbon) and pathogens (Escherichia coli and Enterococci). Temperature, pH, conductivity and dissolved nutrient concentrations (nitrogen, phosphorus and carbon) were however unaffected by the initial peak discharge. After retention in the unvegetated ponds (the first CW compartment) the applied suspended particle peak with a total load of 86.2 kg was reduced by >99%. Similar peak buffering was observed for the turbidity, oxygen demand and settable volume. Simultaneously dissolved nutrient concentrations increased, indicating partial mineralization of the suspended particles during retention in the unvegetated ponds. The peak buffering of pathogens was lower (40-84%), indicating differences in removal processes between other suspended particles and pathogens. The results indicated that the suspended particles were probably mostly removed by sedimentation and mineralization

  9. Measurement of the elution strength and peak shape enhancement at increasing modifier concentration and temperature in RPLC.

    PubMed

    Baeza-Baeza, J J; Dávila, Y; Fernández-Navarro, J J; García-Álvarez-Coque, M C

    2012-12-01

    Two approaches are proposed to measure the effect of different experimental factors (such as the modifier concentration and temperature) on the elution strength and peak shape in reversed-phase liquid chromatography, which quantify the percentage change in the retention factor and peak width (referred to the weakest conditions) per unit change in the experimental factor. The approaches were applied to the separation of a set of flavonoids with aqueous micellar mobile phases of the surfactant Brij-35 (polyoxyethylene(23)dodecanol), in comparison with acetonitrile-water mixtures, using an Eclipse XDB-C18 column. The particular interaction of each flavonoid with the oxyethylene chains of Brij-35 molecules (adsorbed on the stationary phase or forming micelles) changed the elution window, distribution of chromatographic peaks and partitioning kinetics, depending on the hydroxyl substitution in the aromatic rings of flavonoids. At 25 °C, peak shape with Brij-35 mobile phases was significantly poorer with regard to acetonitrile-water mixtures. At increasing temperature, the efficiency of Brij-35 increased, approaching at 80 °C the values obtained at equilibrium conditions, already reached with acetonitrile at 25 °C.

  10. Comparison of nano and conventional liquid chromatographic methods for the separation of (+)-catechin-ethyl-malvidin-3-glucoside diastereoisomers.

    PubMed

    Kučera, Lukáš; Fanali, Salvatore; Aturki, Zeineb; Pospíšil, Tomáš; Bednář, Petr

    2016-01-08

    Nano-liquid chromatography and conventional HPLC were used for the separation of diastereomers of (+)-catechin-ethyl-malvidin-3-glucoside. Those bridged anthocyanin dyes were obtained by reaction of (+)-catechin with malvidin-3-glucoside in the presence of acetaldehyde. Both diastereomers were isolated with semipreparative chromatography and their structures were confirmed by nuclear magnetic resonance and mass spectrometry. In-laboratory prepared capillary columns packed with fully porous particles Chromosphere C18, dp=3μm, core-shell particles Kinetex C18, dp=2.6μm (100μm i.d.) and monolithic column Chromolith CapRod (100μm i.d.) were used for the separation of (+)-catechin, malvidin-3-glucoside and both diastereomers. Chromosphere C18 stationary phase provided the best chromatographic performance. Mobile phase containing water:acetonitrile (80:20) acidified with trifluoroacetic acid (0.1%, v/v/v) was used in an isocratic elution mode with a flow rate of 360nLmin(-1). Separation of studied compounds was achieved in less than 7min under optimized conditions. The nano-liquid chromatographic method and a conventional HPLC one using the same fully porous particles (Chromosphere C18, 3μm, 100mm×4.6mm) were compared providing higher separation efficiency with the first analytical method and similar selectivity. A better peak symmetry and higher resolution of the studied diastereomers was achieved by conventional chromatography. Nevertheless, nano-liquid chromatography appeared to be useful for the separation of complex anthocyanin dyes and can be utilized for their analysis in plant and food micro-samples. The developed method was used for analysis of red wine grape pomace.

  11. Effects of the thermal heterogeneity of the column on chromatographic results.

    PubMed

    Gritti, Fabrice; Guiochon, Georges

    2006-10-27

    The influence of the thermal heterogeneity of HPLC columns on retention data was investigated. The retention factor of the retained compound phenol was measured at 24 increasing values of the flow rate, from 0.025 to 4.9 mL/min, on six different packing materials prepared with the same batch of silica particles (5 microm diameter, 90 A pore size). One column was packed with the neat silica particles, another with the silica endcapped with trimethylchlorosilane (TMS)(C(1), 3.92 micromol/m(2)), and the other four with silica first derivatized with octadecyl-dimethyl-chlorosilane (C(18), 0.42, 1.01, 2.03, and 3.15 micromol/m(2)), and second endcapped with TMS. Four different sources of heat contributing to raise the column temperature were considered: (1) the heat supplied by the hot high-pressure pump chamber to the solvent; (2) the adiabatic (dS=0) compression of the solvent in the high-pressure pump; (3) the isenthalpic (dH=0) decompression of the solvent during its migration along the porous chromatographic bed; and (4) the heat released by the friction of the solvent percolating through the column bed. The main contributions appear to be the heat supplied to the solvent by the HP pump and the friction heat. The average column temperature (ACT) was indirectly derived from the measurements of the first moment, mu(1), of phenol peak, of the column pressure drop, DeltaP, and of the retention factors of the phenol peak apices as a function of the flow rate applied. If the column is placed in a still-air bath at 298 K (and its temperature is not externally controlled), a longitudinal temperature gradient is established along the column and the average column temperature is about 6 K higher when this column is operated at 4.9 mL/min than when the flow rate is only 0.025 mL/min. If the column is placed in a heated air bath (temperature controlled at 316 or 338 K), the ACT changes by less than 3 K over the whole flow rate range applied.

  12. Piper nigrum: micropropagation, antioxidative enzyme activities, and chromatographic fingerprint analysis for quality control.

    PubMed

    Ahmad, Nisar; Abbasi, Bilal Haider; Rahman, Inayat ur; Fazal, Hina

    2013-04-01

    A reliable in vitro regeneration system for the economical and medicinally important Piper nigrum L. has been established. Callus and shoot regeneration was encouraged from leaf portions on Murashige and Skoog (MS) medium augmented with varied concentrations of plant growth regulators. A higher callus production (90 %) was observed in explants incubated on MS medium incorporated with 1.0 mg L(-1) 6-benzyladenine (BA) along with 0.5 mg L(-1) gibberellic acid after 4 weeks of culture. Moreover, a callogenic response of 85 % was also recorded for 1.0 mg L(-1) BA in combination with 0.25 mg L(-1) α-naphthalene acetic acid (NAA) and 0.25 mg L(-1) 2,4-dichlorophenoxyacetic acid or 0.5 mg L(-1) indole butyric acid (IBA) along with 0.25 mg L(-1) NAA and indole acetic acid. Subsequent sub-culturing of callus after 4 weeks of culture onto MS medium supplemented with 1.5 mg L(-1) thiodiazoran or 1.5 mg L(-1) IBA induced 100 % shoot response. Rooted plantlets were achieved on medium containing varied concentrations of auxins. The antioxidative enzyme activities [superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX)] revealed that significantly higher SOD was observed in regenerated plantlets than in other tissues. However, POD, CAT, and APX were higher in callus than in other tissues. A high-performance liquid chromatography (HPLC) fingerprint analysis protocol was established for quality control in different in vitro-regenerated tissues of P. nigrum L. During analysis, most of the common peaks represent the active principle "piperine." The chemical contents, especially piperine, showed variation from callus culture to whole plantlet regeneration. Based on the deviation in chromatographic peaks, the in vitro-regenerated plantlets exhibit a nearly similar piperine profile to acclimated plantlets. The in vitro regeneration system and HPLC fingerprint analysis established here brought a novel approach to the quality control of in vitro

  13. Time-resolved chromatographic analysis and mechanisms in adsorption and catalysis.

    PubMed

    Roubani-Kalantzopoulou, Fani

    2009-03-06

    The main object of this review is the study of fundamentals of adsorption and heterogeneous catalysis, a benefit for the understanding of adsorptive and catalytic properties. This work aims to define and record, with the utmost accuracy, the phenomena and the possible reactions. A new methodology for the study of the adsorption is presented, which is a version of the well-known inverse gas chromatography. This reversed-flow inverse gas chromatography (RF-IGC) is technically very simple, and it is combined with a mathematical analysis that gives the possibility for the estimation of various physicochemical parameters related to adsorbent or catalyst characterization, under conditions compatible with the operation of real adsorbents and catalysts. On this base, this methodology has been successfully applied to the study of the impact of air pollutants, volatile organic and/or inorganic, on many solids such as marbles, ceramics, oxide-pigments of works of art, building materials, authentic statues of the Greek Archaeological Museums. Moreover, this methodology proved to be a powerful tool for studying the topography of active sites of heterogeneous surfaces in the nano-scale domain. Thus, some very important local quantities for the surface chemistry have been determined experimentally for many solids including thin films. These physicochemical local quantities (among which adsorption energy and entropy, surface diffusion coefficient, probability density function) have been determined from the experimental pairs of height of extra chromatographic peaks and time by a nonlinear least-squares method, through personal computer programs written in GW BASIC and lately in FORTRAN. Through the time-resolved analysis the surface characterization of the examined materials took place. In addition, the kinetic constants responsible for adsorption/desorption and surface chemical reactions have also been calculated. Thus, important answers have been provided to the following

  14. [Studying the fertility peak in Beijing].

    PubMed

    Zhong, L

    1989-07-01

    Beijing, China, is experiencing a baby boom in response to 2 periods of large population increase in the mid-1950s and early 1960s. The average number of annual births was 220,000 in the first period and 269,000 in the second period. The causes of the large increase in the population in the first period were an improvement of health conditions which led to a reduction in mortality, immigration flow, and an erroneous population policy. The causes in the second period were recuperative fertility after three years of natural calamity and increased fertility among immigrants. Net migration had an important role in population growth these two periods; it also will have an important impact in future population changes. According to population projections, another baby boom is expected to occur before the end of the end of the century. During the up-coming baby boom period, 1.54 million births are expected, 190,000 per annum. The average increase in population size is expected to 127,000 per year. In the peak year, it may be around 200,000. Thanks to the family planning (FP) program the occurrence of the third baby boom in Beijing has been postponed and the duration will be shortened. From 1972 to 1982, 2.57 million births was averted due to FP, which drastically reduced pressure on the demand for resources and on the momentum of the next baby boom. Another baby booms is not expected during the early half of the 21st century, although an elevated birth rate within the range of normal fluctuation is predicted. The projection was based on the assumption of restricted migration and the enforcement of the FP program. The realization of the projected population will depend on deferred marriage, deferred child-bearing, prolonged birth spacing, the prevention of high parity fertility, the maintenance of the current population policy, and control over the reproductive behavior of the new migrant population.

  15. Optimizing Spillway Capacity With an Estimated Distribution of Floods

    NASA Astrophysics Data System (ADS)

    Resendiz-Carrillo, Daniel; Lave, Lester B.

    1987-11-01

    A model of social cost minimizing spillway capacity for dams is constructed using (1) the estimated distribution of peak flows from historical data, (2) the estimated relationship between spillway capacity and cost, and (3) a characterization of downstream flood damage from dam failure. Net social cost is the sum of construction costs and expected flood damage. This model is applied to data for the Rio Grande River at Embudo, New Mexico. Minimum social cost is attained at a spillway capacity much smaller than that needed to handle a probably maximum flood.

  16. Reversed-phase liquid chromatographic determination of cromolyn sodium in drug substance and select dosage forms.

    PubMed

    Ng, L L

    1994-01-01

    This study, presented as a technical communication, describes a reversed-phase liquid chromatographic method for select commercial formulations, namely, inhalation solution, nasal solution, capsule and inhalation aerosol. Miscellaneous validation parameters are also discussed.

  17. DEVELOPMENT AND VALIDATION OF AN ION CHROMATOGRAPHIC METHOD FOR DETERMINING PERCHLORATE IN FERTILIZERS

    EPA Science Inventory

    A method has been developed for the determination of perchlorate in fertilizers. Materials are leached with deionized water to dissolve any soluble perchlorate compounds. Ion chromatographic separation is followed by suppressed conductivity for detection. Perchlorate is retained ...

  18. 21 CFR 862.2230 - Chromatographic separation material for clinical use.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... chromatographic separation material for clinical use is a device accessory (e.g., ion exchange absorbents, ion exchagne resins, and ion papers) intended for use in ion exchange chromatography, a procedure in which...

  19. 21 CFR 862.2230 - Chromatographic separation material for clinical use.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... chromatographic separation material for clinical use is a device accessory (e.g., ion exchange absorbents, ion exchagne resins, and ion papers) intended for use in ion exchange chromatography, a procedure in which...

  20. 21 CFR 862.2230 - Chromatographic separation material for clinical use.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... chromatographic separation material for clinical use is a device accessory (e.g., ion exchange absorbents, ion exchagne resins, and ion papers) intended for use in ion exchange chromatography, a procedure in which...

  1. Oxygen carrier for gas chromatographic analysis of inert gases in propellants

    NASA Technical Reports Server (NTRS)

    Cannon, W. A.

    1972-01-01

    Gas chromatographic determination of small quantities of inert gases in reactive propellants is discussed. Operating conditions used for specific analyses of helium in diborane and nitrogen in oxygen difluoride are presented in tabular form.

  2. A Miniature Gas Chromatograph Mass Spectrometer (GCMS) for Planetary Atmospheres Studies

    NASA Astrophysics Data System (ADS)

    Simcic, J.; Madzunkov, S. M.; Bae, B.; Nikolic, D.; Darrach, M.

    2016-10-01

    Presented herein are the latest achievements in developing an instrument with the same analytical performance of commercial Gas Chromatograph Mass Spectrometer systems but approximately an order of magnitude smaller and optimized for space missions.

  3. HIGH PERFORMANCE LIQUID CHROMATOGRAPHIC SEPARATION OF THE ENANTIOMERS OF ORGANOPHOSPHORUS PESTICIDES ON POLYSACCHARIDE CHIRAL STATIONARY PHASES

    EPA Science Inventory

    High-performance liquid chromatographic separation of the individual enantiomers of 12 organophosphorus pesticides (OPs) was obtained on polysaccharide enantioselective HPLC columns using alkane-alcohol mobile phase. The OP pesticides were crotoxyphos, dialifor, fonofos, fenamiph...

  4. Comparison evaluation of liquid chromatographic and bioassay methods of analysis for determination of paralytic shellfish poisons in shellfish tissues.

    PubMed

    Salter, J E; Timperi, R J; Hennigan, L J; Sefton, L; Reece, H

    1989-01-01

    A liquid chromatographic (LC) method was compared with the AOAC mouse bioassay method (18.086-18.092) for determination of paralytic shellfish toxins in shellfish tissues. Shellfish samples were collected from Massachusetts coastal waters as part of a state surveillance program, and extracts of shellfish meat were analyzed for toxins by using both analytical methods. Overall correlation of the LC and bioassay methods is good (r = 0.943), but for samples with toxicities less than 100 micrograms saxitoxin/100 g shellfish meat, the correlation is significantly less (r = 0.531). Limits of detection are 10 micrograms saxitoxin/100 g shellfish meat and 40 micrograms saxitoxin/100 g shellfish meat for the LC and bioassay methods, respectively. Analytical capacity of the LC method is limited to 12 samples/person-day compared with 30 samples/person-day for the bioassay. Sampling capacity of the LC method could be increased by using a fluorescence detector with a wider response range, which would eliminate the need for dilution of concentrated samples.

  5. Effects of regulation on L-moments of annual peak streamflow in Texas

    USGS Publications Warehouse

    Asquith, William H.

    2001-01-01

    Several techniques exist to estimate annual peak-streamflow frequency for streamflows that have recurrence intervals ranging from 2 to 500 years for natural (unregulated) drainage basins in Texas. Unfortunately, such techniques have limited applicability in regulated basins. There are numerous regulated basins throughout Texas, which has more than 7,000 dams that are identified by Texas Natural Resource Conservation Commission permits. The effects on annual peak streamflow from reservoirs created by these dams range from negligible to the complete suppression of the flood hydrograph; also, reservoirs can artificially create flood-like hydrographs. The large number of reservoirs and their widespread distribution in Texas necessitate an assessment of flood characteristics in regulated basins. Therefore, the U.S. Geological Survey, in cooperation with the Texas Department of Transportation, conducted a study of the effects of regulation on L-moments of annual peak streamflow in Texas.For this report, the State was divided into three regions. Four regression equations to estimate the L-moments of natural annual peak-streamflow data for ungaged sites were derived for each region from data for 367 streamflow-gaging stations in natural basins. The explanatory variables in the equations are contributing drainage area, basin shape factor, and stream slope. The effects of regulation on the L-moments of annual peak-streamflow data were determined by analysis of maximum and normal storage-capacity data from reservoirs for 96 streamflow-gaging stations in variously regulated basins. The results indicate that as potential flood storage (defined by the difference between total maximum and normal capacity) in a basin increases, the mean annual peak streamflow decreases nonlinearly. Evidence strongly indicates (despite contrary expectation) that the higher L-moments (coefficient of L-variation, L-skew, and L-kurtosis) are unaffected by regulation.

  6. Impacts of Mountain Pine Beetle on Peak Flow in the Fraser Basin in British Columbia

    NASA Astrophysics Data System (ADS)

    Scheffler, C.; Rosin, K.; Weiler, M.

    2008-12-01

    Increasing winter temperature in combination with forest management practices are the main drivers for the Mountain Pine Beetle (MPB) epidemic in British Columbia (BC). The infestation of MPB has now turned into a major threat to the natural habitat of the province. The Fraser basin, the largest watershed in BC, is the most affected watershed with an infested forest area of 7.7 million hectares (88% of the watershed) [Redding and Pike 2007]. Forest cover is a key modifier of the watershed's peak flow regime. The peak flow generally increases when forest cover is reduced. Major parts of the Fraser basin have only a limited number of gauging stations (or are even ungauged). The goal of the project was to develop a hydrological model that can predict peak flow increases but does not rely on complex data inputs for its validation and calibration procedures. The model consists of two major components: climate input and runoff. The climate input component determines the mean annual snowmelt as well as the maximum rainfall based on long term climatic averages. This information is then used to determine the time and the capacity of the peak flow for every 3rd order watershed. The runoff component delineates hydrologic processes such as Hortonain Overland Flow, Saturation Overland Flow and Shallow Surface Flow. The model combines the two components and computes a map of peak flow contribution. A peak flow analysis has been carried out to validate the model results using available gauging stations in subcatchments. The validated model has been then applied to the entire watershed to analyze the impacts of MPB on peak flow in the Fraser basin. The presentation will show the conceptual presentation of the hydrological model. It will highlight the results of the peak flow analysis and show initial results of the application of the model. Cited Literature: Redding, T. and Pike, R (2007). Mountain Pine Beetle and Watershed Hydrology Workshop Summary, Streamline Watershed

  7. The role of building technologies in reducing and controlling peak electricity demand

    SciTech Connect

    Koomey, Jonathan; Brown, Richard E.

    2002-09-01

    Peak power demand issues have come to the fore recently because of the California electricity crisis. Uncertainties surrounding the reliability of electric power systems in restructured markets as well as security worries are the latest reasons for such concerns, but the issues surrounding peak demand are as old as the electric utility system itself. The long lead times associated with building new capacity, the lack of price response in the face of time-varying costs, the large difference between peak demand and average demand, and the necessity for real-time delivery of electricity all make the connection between system peak demand and system reliability an important driver of public policy in the electric utility sector. This exploratory option paper was written at the request of Jerry Dion at the U.S.Department of Energy (DOE). It is one of several white papers commissioned in 2002 exploring key issues of relevance to DOE. This paper explores policy-relevant issues surrounding peak demand, to help guide DOE's research efforts in this area. The findings of this paper are as follows. In the short run, DOE funding of deployment activities on peak demand can help society achieve a more economically efficient balance between investments in supply and demand-side technologies. DOE policies can promote implementation of key technologies to ameliorate peak demand, through government purchasing, technology demonstrations, and improvements in test procedures, efficiency standards, and labeling programs. In the long run, R&D is probably the most important single leverage point for DOE to influence the peak demand issue. Technologies for time-varying price response hold great potential for radically altering the way people use electricity in buildings, but are decades away from widespread use, so DOE R&D and expertise can make a real difference here.

  8. Heat Capacity Mapping Mission

    NASA Technical Reports Server (NTRS)

    Nilsson, C. S.; Andrews, J. C.; Scully-Power, P.; Ball, S.; Speechley, G.; Latham, A. R. (Principal Investigator)

    1980-01-01

    The Tasman Front was delineated by airborne expendable bathythermograph survey; and an Heat Capacity Mapping Mission (HCMM) IR image on the same day shows the same principal features as determined from ground-truth. It is clear that digital enhancement of HCMM images is necessary to map ocean surface temperatures and when done, the Tasman Front and other oceanographic features can be mapped by this method, even through considerable scattered cloud cover.

  9. Community Capacity Building

    PubMed Central

    Goytia, Crispin N.; Todaro-Rivera, Lea; Brenner, Barbara; Shepard, Peggy; Piedras, Veronica; Horowitz, Carol

    2013-01-01

    Background: Successful community–academic research partnerships require building the capacity of both community-based organizations (CBOs) and academics to conduct collaborative research of mutual interest and benefit. Yet, information about the needs and goals of research-interested CBOs is lacking. Our partnership aimed to conduct a community research needs assessment and to use results to develop future capacity-building programs for CBOs. Methods: Based on our review of the literature, informal interviews with research-interested CBOs and community-engaged research groups locally and nationally, we developed a needs assessment survey. Key domains of this survey included history and experience with research collaboration, interest in specific research topics, and preference for learning format and structure. We trained community health workers (CHWs) to recruit senior leaders from CBOs in New York City (NYC) and encourage them to complete an on-line survey. Results: Fully 54% (33/61) of CBOs completed the needs assessment. Most (69%) reported involvement with research or evaluation in the last 2 years and 33% had some funding for research. Although 75% had collaborated with academic institutions in the past, 58% did not rate this experience well. The four areas respondents prioritized for skills building were program evaluation, developing needs assessments, building surveys, and understanding statistical analyses. They were less interested in learning to build collaborations with academics. Conclusions: A formal needs assessment of research training and educational needs of CBOs revealed that most had experience, albeit negative, with academic collaborations. CBO leaders wanted to build skills to conduct and analyze assessments and program evaluations. Our community–academic partnership is using these findings to develop a research capacity-building course. Other partnerships should consider conducting such assessments to transform the capacity of CBOs to

  10. Enhancing capacity management.

    PubMed

    Rees, Susan; Houlahan, Beth; Lavrenz, Dennise

    2014-03-01

    It is essential for organizations to be able to accept patients requiring care. Capacity planning and management are necessary to ensure an organization has an accepting physician/service, an available bed, and staff to care for the patient and family. This organization implemented strategies including communication plans, staffing guidelines, morning rounds, proactive planning, and an escalation process to reverse the trend of not being able to accept all patients.

  11. Enabling Partner Capacity Building

    DTIC Science & Technology

    2013-03-01

    Market Street, Philadelphia, PA 19104, (215) 662-5606. The Commission on Higher Education is an institutional accrediting agency recognized by the U.S...valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) xx-03-2013 2. REPORT TYPE STRATEGY ...National Security Strategy emphasizes building the capacity of our allies and partner countries to share the burden of global leadership. The Army is

  12. Chromatographic extraction with di(2-ethylhexyl)orthophosphoric acid for production and purification of promethium-147

    DOEpatents

    Boll, Rose A [Knoxville, TN

    2008-10-14

    A method of producing and purifying promethium-147 including the steps of: irradiating a target material including neodymium-146 with neutrons to produce promethium-147 within the irradiated target material; dissolving the irradiated target material to form an acidic solution; loading the acidic solution onto a chromatographic separation apparatus containing HDEHP; and eluting the apparatus to chromatographically separate the promethium-147 from the neodymium-146.

  13. High-resolution gas chromatographic profiles of volatile organic compounds produced by microorganisms at refrigerated temperatures.

    PubMed Central

    Lee, M L; Smith, D L; Freeman, L R

    1979-01-01

    Three different strains of bacteria isolated from spoiled, uncooked chicken were grown in pure culture on Trypticase soy agar supplemented with yeast extract. The volatile organic compounds produced by each culture were concentrated on a porous polymer precolumn and analyzed by high-resolution gas chromatographic mass spectrometry. Twenty different compounds were identified. Both qualitative and quantitative differences in the chromatographic profiles from each culture were found. PMID:104660

  14. Multidimensional High-Resolution Gas Chromatographic Investigations of Hydrocarbon Fuels and Various Turbine Engine Fuel Precursors.

    DTIC Science & Technology

    1985-08-01

    Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy . 15. B. Welton, Column Switching and Backflush Techniques with Open Tubular and...Packed Columns in Gas Chromatography, Paper presented at 1978 Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy . 16. R. Miller... Applied Spectroscopy . 33. J. F. Pankow and L. M. Isabelle, Interface of the Direct Coupling of a Second Gas Chromatograph to a Gas Chromatograph/ Mass

  15. CSTI high capacity power

    SciTech Connect

    Winter, J.M.

    1994-09-01

    The SP-100 program was established in 1983 by DOD, DOE, and NASA as a joint program to develop the technology necessary for space nuclear power systems for military and civil application. During FY86 and 87, the NASA SP-100 Advanced Technology Program was devised to maintain the momentum of promising technology advancement efforts started during Phase I of SP-100 and to strengthen, in key areas, the chances for successful development and growth capability of space nuclear reactor power systems for future space applications. In FY88, the Advanced Technology Program was incorporated into NASA`s new Civil Space Technology Initiative (CSTI). The CSTI Program was established to provide the foundation for technology development in automation and robotics, information, propulsion, and power. The CSTI High Capacity Power Program builds on the technology efforts of the SP-100 program, incorporates the previous NASA SP-100 Advanced Technology project, and provides a bridge to NASA Project Pathfinder. The elements of CSTI High Capacity Power development include Conversion Systems, Thermal Management, Power Management, System Diagnostics, and Environmental Interactions. Technology advancement in all areas, including materials, is required to assure the high reliability and 7 to 10 year lifetime demanded for future space nuclear power systems. The overall program will develop and demonstrate the technology base required to provide a wide range of modular power systems as well as allowing mission independence from solar and orbital attitude requirements. Several recent advancements in CSTI High Capacity power development will be discussed.

  16. CSTI High Capacity Power

    NASA Technical Reports Server (NTRS)

    Winter, Jerry M.

    1989-01-01

    The SP-100 program was established in 1983 by DOD, DOE, and NASA as a joint program to develop the technology necessary for space nuclear power systems for military and civil application. During FY-86 and 87, the NASA SP-100 Advanced Technology Program was devised to maintain the momentum of promising technology advancement efforts started during Phase 1 of SP-100 and to strengthen, in key areas, the chances for successful development and growth capability of space nuclear reactor power systems for future space applications. In FY-88, the Advanced Technology Program was incorporated into NASA's new Civil Space Technology Initiative (CSTI). The CSTI Program was established to provide the foundation for technology development in automation and robotics, information, propulsion, and power. The CSTI High Capacity Power Program builds on the technology efforts of the SP-100 program, incorporates the previous NASA SP-100 Advanced Technology project, and provides a bridge to NASA Project Pathfinder. The elements of CSTI High Capacity Power development include Conversion Systems, Thermal Management, Power Management, System Diagnostics, and Environmental Interactions. Technology advancement in all areas, including materials, is required to assure the high reliability and 7 to 10 year lifetime demanded for future space nuclear power systems. The overall program will develop and demonstrate the technology base required to provide a wide range of modular power systems as well as allowing mission independence from solar and orbital attitude requirements. Several recent advancements in CSTI High Capacity power development will be discussed.

  17. Aerobic Capacity in Children and Adolescents with Cerebral Palsy

    ERIC Educational Resources Information Center

    Verschuren, Olaf; Takken, Tim

    2010-01-01

    This study described the aerobic capacity [VO[subscript 2peak] (ml/kg/min)] in contemporary children and adolescents with cerebral palsy (CP) using a maximal exercise test protocol. Twenty-four children and adolescents with CP classified at Gross Motor Functional Classification Scale (GMFCS) level I or level II and 336 typically developing…

  18. Comprehensive two-dimensional gas chromatographic separations with a temperature programmed microfabricated thermal modulator.

    PubMed

    Collin, William R; Nuñovero, Nicolas; Paul, Dibyadeep; Kurabayashi, Katsuo; Zellers, Edward T

    2016-04-29

    Comprehensive two-dimensional gas chromatography (GC×GC) with a temperature-programmed microfabricated thermal modulator (μTM) is demonstrated. The 0.78 cm(2), 2-stage μTM chip with integrated heaters and a PDMS coated microchannel was placed in thermal contact with a solid-state thermoelectric cooler and mounted on top of a bench scale GC. It was fluidically coupled through heated interconnects to an upstream first-dimension ((1)D) PDMS-coated capillary column and a downstream uncoated capillary or second-dimension ((2)D) PEG-coated capillary. A mixture of n-alkanes C6-C10 was separated isothermally and the full-width-at-half-maximum (fwhm) values of the modulated peaks were assessed as a function of the computer-controlled minimum and maximum stage temperatures of μTM, Tmin and Tmax, respectively. With Tmin and Tmax fixed at -25 and 100°C, respectively, modulated peaks of C6 and C7 had fwhm values<53 ms while the modulated peaks of C10 had a fwhm value of 1.3s, due to inefficient re-mobilization. With Tmin and Tmax fixed at 0 and 210°C, respectively, the fwhm value for the modulated C10 peaks decreased to 67 ms, but C6 and C7 exhibited massive breakthrough. By programming Tmin from -25 to 0°C and Tmax from 100 to 220°C, the C6 and C7 peaks had fwhm values≤50 ms, and the fwhm for C10 peaks remained<95 ms. Using the latter conditions for the GC×GC separation of a sample of unleaded gasoline yielded resolution similar to that reported with a commercial thermal modulator. Replacing the PDMS phase in the μTM with a trigonal-tricationic room temperature ionic liquid eliminated the bleed observed with the PDMS, but also reduced the capacity for several test compounds. Regardless, the demonstrated capability to independently temperature program this low resource μTM enhances its versatility and its promise for use in bench-scale GC×GC systems.

  19. Liquid chromatographic analysis of cinchona alkaloids in beverages.

    PubMed

    Horie, Masao; Oishi, Mitsuo; Ishikawa, Fusako; Shindo, Tetsuya; Yasui, Akiko; Ogino, Shuzo; Ito, Koichi

    2006-01-01

    A method for the determination of Cinchona extract (whose main components are the alkaloids cinchonine, cinchonidine, quinidine, and quinine) in beverages by liquid chromatography was developed. A beverage with an alcohol content of more than 10% was loaded onto an OASIS HLB solid-phase extraction cartridge, after it was adjusted to pH 10 with 28% ammonium hydroxide. Other beverages were centrifuged at 4000 rpm for 5 min, and the supernatant was loaded onto the cartridge. The cartridge was washed with water followed by 15% methanol, and the Cinchona alkaloids were eluted with methanol. The Cinchona alkaloids in the eluate were chromatographed on an L-column ODS (4.6 mm id x 150 mm) with methanol and 20 mmol/L potassium dihydrogen phosphate (3 + 7) as the mobile phase. Cinchona alkaloids were monitored with an ultraviolet (UV) detector at 230 nm, and with a fluorescence detector at 405 nm for cinchonine and cinchonidine and 450 nm for quinidine and quinine (excitation at 235 nm). The calibration curves for Cinchona alkaloids with the UV detector showed good linearity in the range of 2-400 microg/mL. The detection limit of each Cinchona alkaloid, taken to be the concentration at which the absorption spectrum could be identified, was 2 microg/mL. The recovery of Cinchona alkaloids added at a level of 100 microg/g to various kinds of beverages was 87.6-96.5%, and the coefficients of variation were less than 3.3%. A number of beverage samples, some labeled to contain bitter substances, were analyzed by the proposed method. Quinine was detected in 2 samples of carbonated beverage.

  20. Ion chromatographic identification and quantification of glycol degradation products.

    PubMed

    Madera, M; Höflinger, W; Kadnar, R

    2003-05-16

    In water-based heat transfer systems, frequently glycols are added to the water to obtain freeze protection. For this purpose, ethylene glycol (EG) is the most common substance used. When heated, the glycol will slowly degrade and the pH of the glycol-water mixture will decrease, leading to corrosion and foaming problems. Carboxylic acids were identified as the main degradation products. Quantification of the carboxylic acids is of importance to monitor the degradation reactions in order to identify hot spots or overheating, caused by severe heat exchanger scaling, where pH measurements will not be sufficient due to buffer substances added for corrosion protection. In this work, ion chromatographic methods havebeen developed to identify the main degradation products of EG in heat transfer systems and to monitor the degradation process. Possible acidic reaction products of EG are glycolic acid, glyoxylic acid, oxalic acid, acetic acid and formic acid. Separations with a Dionex AS9-HC column with Na2CO3 eluents of differing concentrations showed that only trace amounts of carboxylic acids are present in aged heat transfer media. Oxalic acid can be quantified simultaneously to nitrite or molybdate which are added as corrosion inhibitors. A Dionex AS10 separation column with Na2B4O7 eluent enabled base line separation of glycolic acid, acetic acid and formic acid. Heat transfer media, which are operated in different heat transfer systems under different conditions, were analysed. A system was identified, where severe overheating due to fluid maldistribution in the heat exchanger took place.