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Sample records for chromatography techniques applications

  1. Separation techniques: Chromatography

    PubMed Central

    Coskun, Ozlem

    2016-01-01

    Chromatography is an important biophysical technique that enables the separation, identification, and purification of the components of a mixture for qualitative and quantitative analysis. Proteins can be purified based on characteristics such as size and shape, total charge, hydrophobic groups present on the surface, and binding capacity with the stationary phase. Four separation techniques based on molecular characteristics and interaction type use mechanisms of ion exchange, surface adsorption, partition, and size exclusion. Other chromatography techniques are based on the stationary bed, including column, thin layer, and paper chromatography. Column chromatography is one of the most common methods of protein purification. PMID:28058406

  2. Membrane-based sample preparation for ion chromatography-Techniques, instrumental configurations and applications.

    PubMed

    Frenzel, Wolfgang; Markeviciute, Inga

    2017-01-06

    Sample preparation is the bottleneck of many analytical methods, including ion chromatography (IC). Procedures based on the application of membranes are important, yet not well appreciated means for clean-up and analyte preconcentration of liquid samples. Filtration, ultrafiltration, the variety of dialysis techniques, i.e. passive dialysis, Donnan dialysis and electrodialysis, as well as gas-diffusion are being reviewed here with respect to their application in combination with IC. Instrumental aspects including hardware requirements, configuration of membrane separation units and membrane characteristics are presented. Operation in batch and flow-through mode is described with emphasis on the latter to in-line coupling with IC, permitting fully automated operation. Attention is also drawn to dialysis probes and microdialysis both providing options for in-situ measurements with inherent selective sampling of analytes and sample preparation. The respective features of the various techniques are outlined with respect to the possibilities of matrix removal and selectivity enhancement. In this article, we provide examples of application of the diverse membrane separation techniques and discuss the benefits and limitations thereof.

  3. Advancement and application of gas chromatography isotope ratio mass spectrometry techniques for atmospheric trace gas analysis

    NASA Astrophysics Data System (ADS)

    Giebel, Brian M.

    2011-12-01

    The use of gas chromatography isotope ratio mass spectrometry (GC-IRMS) for compound specific stable isotope analysis is an underutilized technique because of the complexity of the instrumentation and high analytical costs. However stable isotopic data, when coupled with concentration measurements, can provide additional information on a compounds production, transformation, loss, and cycling within the biosphere and atmosphere. A GC-IRMS system was developed to accurately and precisely measure delta13C values for numerous oxygenated volatile organic compounds having natural and anthropogenic sources. The OVOCs include methanol, ethanol, acetone, methyl ethyl ketone, 2-pentanone, and 3-pentanone. Guided by the requirements for analysis of trace components in air, the GC-IRMS system was developed with the goals of increasing sensitivity, reducing dead-volume and peak band broadening, optimizing combustion and water removal, and decreasing the split ratio to the IRMS. The technique relied on a two-stage preconcentration system, a low-volume capillary reactor and water trap, and a balanced reference gas delivery system. Measurements were performed on samples collected from two distinct sources (i.e. biogenic and vehicle emissions) and ambient air collected from downtown Miami and Everglades National Park. However, the instrumentation and the method have the capability to analyze a variety of source and ambient samples. The measured isotopic signatures that were obtained from source and ambient samples provide a new isotopic constraint for atmospheric chemists and can serve as a new way to evaluate their models and budgets for many OVOCs. In almost all cases, OVOCs emitted from fuel combustion were enriched in 13C when compared to the natural emissions of plants. This was particularly true for ethanol gas emitted in vehicle exhaust, which was observed to have a uniquely enriched isotopic signature that was attributed to ethanol's corn origin and use as an alternative

  4. Development and Application of a Fast Chromatography Technique for Analysis of Biogenic Volatile Organic Compounds in Plant Emissions

    NASA Astrophysics Data System (ADS)

    Jones, C. E.; Kato, S.; Nakashima, Y.; Yamazakii, S.; Kajii, Y. J.

    2011-12-01

    Biogenic volatile organic compounds (BVOCs) emitted from vegetation constitute the largest fraction (>90 %) of total global non-methane VOC supplied to the atmosphere, yet the chemical complexity of these emissions means that achieving comprehensive measurements of BVOCs, and in particular the less volatile terpenes, is not straightforward. As such, there is still significant uncertainty associated with the contribution of BVOCs to the tropospheric oxidation budget, and to atmospheric secondary organic aerosol (SOA) formation. The rate of BVOC emission from vegetation is regulated by environmental conditions such as light intensity and temperature, and thus can be highly variable, necessitating high time-resolution BVOC measurements. In addition, the numerous monoterpene and sesquiterpene isomers, which are indistinguishable by some analytical techniques, have greatly varying lifetimes with respect to atmospheric oxidants, and as such quantification of each individual isomer is fundamental to achieving a comprehensive characterisation of the impact of BVOCs upon the atmospheric oxidation capacity. However, established measurement techniques for these trace gases typically offer a trade-off between sample frequency and the level of speciation; detailed information regarding chemical composition may be obtained, but with reduced time resolution, or vice versa. We have developed a Fast-GC-FID technique for quantification of a range of monoterpene, sesquiterpene and oxygenated C10 BVOC isomers, which retains the separation capability of conventional gas chromatography, yet offers considerably improved sample frequency. Development of this system is ongoing, but currently a 20 m x 0.18 mm i.d resistively heated metal column is employed to achieve chromatographic separation of thirteen C10-C15 BVOCs, within a total cycle time of ~15 minutes. We present the instrument specifications and analytical capability, together with the first application of this Fast-GC technique

  5. Application of capillary gas chromatography mass spectrometry/computer techniques to synoptic survey of organic material in bed sediment

    USGS Publications Warehouse

    Steinheimer, T.R.; Pereira, W.E.; Johnson, S.M.

    1981-01-01

    A bed sediment sample taken from an area impacted by heavy industrial activity was analyzed for organic compounds of environmental significance. Extraction was effected on a Soxhlet apparatus using a freeze-dried sample. The Soxhlet extract was fractionated by silica gel micro-column adsorption chromatography. Separation and identification of the organic compounds was accomplished by capillary gas chromatography/mass spectrometry techniques. More than 50 compounds were identified; these include saturated hydrocarbons, olefins, aromatic hydrocarbons, alkylated polycyclic aromatic hydrocarbons, and oxygenated compounds such as aldehydes and ketones. The role of bed sediments as a source or sink for organic pollutants is discussed. ?? 1981.

  6. [Application of liquid chromatography in substitution of the radioimmunoassay technique in order to reduce residues generated in health services in research laboratory].

    PubMed

    Ribeiro Neto, Luciane M; Sugawara, Eduardo K; Verreschi, Ieda T N

    2008-10-01

    Designing a Health Care Service Waste Management Plan, according to the RDC 306 rules, is a responsibility of all those who produce such waste. Since radioimmunoassay (RIA) is one of the most employed techniques, we studied the impact of replacing this technique by liquid chromatography (HPLC) with regard to the reduction of the radioactive residues routinely produced by the Unifesp steroid laboratory. The residues produced by the determination of serum cortisol and 17 alpha-hydroxyprogesterone were classified, and those belonging to groups B and C were evaluated. We observed that, when RIA is used, chemical residues (group B) and radioactive waste (group C) are produced, whereas HPLC generates only chemical residues. Adequation of these techniques showed to be advantageous, by significantly reducing the time of analysis and mainly by eliminating and/or reducing the generation of radioactive waste, encouraging its application to other methodologies, as well as its adoption by other research units.

  7. Emulsion-cryogelation technique for fabricating a versatile toolbox of hierarchical polymeric monolith and its application in chromatography.

    PubMed

    Li, Yaping; Qi, Li; Li, Nan; Ma, Huimin

    2016-05-15

    A novel poly (glycidyl methacrylate-co-ethylene dimethacrylate) monolith has been fabricated via the environmental friendly cryogelation-emulsion technique. The polymerization process is assisted by self-assembly of typical tri-block copolymer Pluronic F127 at sub-zero temperature using ice crystal as template, which can avoid consumption of organic porogenic solvents and thermal unstability of emulsion system. The developed monolith possesses hierarchical networks, which is confirmed by nitrogen adsorption measurement, mercury intrusion porosimetry, scanning electron microscopy and permeability testing. Further, the effect of the amounts of Pluronic F127 on the microstructure has been investigated. Moreover, the prepared polymer monolith undergoes acidic hydrolysis of epoxy groups into hydroxyl groups on the surface and its liquid chromatographic performance is explored by separating model analytes. The results indicate that the unique porous polymer monolith with hierarchical networks could be prepared via an organic porogen-free approach and used for analysis of polar and nonpolar molecules, extending the application of cryogelation-emulsion technique and methacrylate-based monolith.

  8. Rolling--a new application technique for luminescent bacteria on high-performance thin-layer chromatography plates.

    PubMed

    Baumgartner, Vera; Hohl, Christopher; Schwack, Wolfgang

    2011-05-13

    High-performance thin-layer chromatography (HPTLC) coupled with bioluminescence detection using Vibrio fischeri bacteria can be used for screening for unknown substances. This is accomplished by dipping the HPTLC plate in an aqueous bacteria solution. Especially polar substances, however, can start to dissolve during this process, which leads to blurring and tailing of the zones on the plate. To overcome this disadvantage, we applied the bacteria solution by rolling. This method has been described for chemical derivatizations, but is very rarely used. The rolling device was made of commercially available household articles. Using octhilinone and methylparaben as test compounds, rolling was compared with dipping. Despite of performing the rolling process manually, the results were reproducible. Depending on the substance and its amount on the HPTLC plate, peaks were narrower, up to a factor of 4 higher and with a higher signal-to-noise ratio than after dipping. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Application of Liquid Chromatography/Ion Trap Mass Spectrometry Technique to Determine Ergot Alkaloids in Grain Products

    PubMed Central

    Szymczyk, Krystyna; Jędrzejczak, Renata; Roszko, Marek

    2015-01-01

    Summary A liquid chromatography/ion trap mass spectrometry-based method to determine six ergot alkaloids and their isomers is presented. The samples were cleaned on neutral alumina-based solid-phase extraction cartridges. The following method parameters were obtained (depending on the analyte and spiking level): method recovery from 63.0 to 104.6%, relative standard deviation below 18%, linear range from 1 to 325 µg/kg, linear correlation coefficient not less than 0.98. The developed analytical procedure was applied to determine the levels of ergot alkaloids in 65 samples of selected rye-based food products (flour – 34 samples, bran – 12 samples, rye – 18 samples, flakes – 1 sample). Measurable levels of alkaloids were found in majority of the analysed samples, particularly in rye flour. Additionally, alkaloids were determined in ergot sclerotia isolated from rye grains. Total content was nearly 0.01% (97.9 mg/kg). However, the alkaloid profile was dominated by ergocristine at 45.6% (44.7 mg/kg), an alkaloid not commonly found in the tested food products. Ergocorninine at 0.2% (0.2 mg/kg) was the least abundant alkaloid. PMID:27904328

  10. Application of microscopy technique and high-performance liquid chromatography for quality assessment of the flower bud of Tussilago farfara L. (Kuandonghua)

    PubMed Central

    Li, Da; Liang, Li; Zhang, Jing; Kang, Tingguo

    2015-01-01

    Background: Quality control is one of the bottleneck problems limiting the application and development of traditional Chinese medicine (TCM). In recent years, microscopy and high-performance liquid chromatography (HPLC) techniques have been frequently applied in the quality control of TCM. However, studies combining conventional microscopy and HPLC techniques for the quality control of the flower bud of Tussilago farfara L. (Kuandonghua) have not been reported. Objective: This study was undertaken to evaluate the quality of the flower bud of T. farfara L. and to establish the relationships between the quantity of pollen grains and four main bioactive constituents: tussilagone, chlorogenic acid, rutin and isoquercitrin. Materials and Methods: In this study, microscopic examination was used to quantify microscopic characteristics of the flower bud of T. farfara L., and the chemical components were determined by HPLC. The data were analyzed by Statistical Package for the Social Sciences statistics software. Results: The results of the analysis showed that tussilagone, chlorogenic acid, rutin and isoquercitrin were significantly correlated with the quantity of pollen grains in the flower bud of T. farfara L. There is a positive correlation between them. From these results, it can be deduced that the flower bud of T. farfara L. with a greater quantity of pollen grains should be of better quality. Conclusion: The study showed that the established method can be helpful for evaluating the quality of the flower bud of T. farfara L. based on microscopic characteristic constants and chemical quantitation. PMID:26246737

  11. Determination of lysergic acid diethylamide (LSD) by application of online 77 K fluorescence spectroscopy and a sweeping technique in micellar electrokinetic chromatography.

    PubMed

    Fang, Ching; Liu, Ju-Tsung; Lin, Cheng-Huang

    2002-10-16

    The principal advantage of the use of Shopl'skii effect (low temperature spectrum) is that spectral sharpening occurs both in absorption and emission. However, thus far using the technique of capillary electrophoresis/low temperature fluorescence spectroscopy (CE/LTFS) either at 77 or 4.2 K remains difficult to obtain an on-line spectrum, if the analyte is present at low concentration. This paper examines the feasibility of combining the techniques of online concentration and CE/LTFS to identify LSD and related compounds in urine at 77 K. To improve sensitivity, sweeping-micellar electrokinetic chromatography (sweeping-MEKC) and cation-selective exhaustive injection-sweep-micellar electrokinetic chromatography (CSEI-sweep-MEKC) were used for on-line concentration which resulted in detection limits of approximately 20 approximately 60 ppt, respectively.

  12. Mixed-mode chromatography and its applications to biopolymers.

    PubMed

    Yang, Yun; Geng, Xindu

    2011-12-09

    Mixed-mode chromatography is a type of chromatography in which a chromatographic stationary phase interacts with solutes through more than one interaction mode. This technique has been growing rapidly because of its advantages over conventional chromatography, such as its high resolution, high selectivity, high sample loading, high speed, and the ability to replace two conventionally corresponding columns in certain circumstances. In this work, some aspects of the development of mixed-mode chromatography are reviewed, such as stationary phase preparation, combinations of various separation modes, separation mechanisms, typical applications to biopolymers and peptides, and future prospects. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. Application of Solid Sorbent Collection Techniques and High Performance Liquid Chromatography with Electrochemical Detection to the Analysis of Explosives in Water Samples.

    DTIC Science & Technology

    1986-11-01

    Methods were developed for the determination of several explosives components (nitro-organic compounds) in environmental waters. The methods are based on Porapak resin adsorption and Amberlite XAD-4 resin adsorption of the explosives are measured by high performance liquid chromatography with electrochemical detection. The technique provides a high degree of selectivity and sensitivity for these compounds in actual samples. Detection limits approach 1 microgram/l for many components.

  14. Development and application of compact denuder sampling techniques with in situ derivatization followed by gas chromatography-mass spectrometry for halogen speciation in volcanic plumes

    NASA Astrophysics Data System (ADS)

    Rüdiger, Julian; Bobrowski, Nicole; Hoffmann, Thorsten

    2015-04-01

    Volcanoes are a large source for several reactive atmospheric trace gases including sulphur and halogen containing species. The detailed knowledge of volcanic plume chemistry can give insights into subsurface processes and can be considered as a useful geochemical tool for monitoring of volcanic activity, especially halogen to sulphur ratios (e.g. Bobrowski and Giuffrida, 2012; Donovan et al., 2014). The reactive bromine species bromine monoxide (BrO) is of particular interest, because BrO as well as SO2 are readily measurable by UV spectrometers at a safe distance. Furthermore it is formed in the plume by a multiphase reaction mechanism under depletion of ozone in the plume. The abundance of BrO changes as a function of the reaction time and therefore distance from the vent as well as the spatial position in the plume. Due to the lack of analytical approaches for the accurate speciation of certain halogens (HBr, Br2, Br, BrCl, HOBr etc.) there are still uncertainties about the magnitude of volcanic halogen emissions and in particular their specificationtheir species and therefore also in the understanding of the bromine chemistry in volcanic plumes (Bobrowski et al., 2007). In this study, the first application of a 1,3,5-trimethoxybenzene (1,3,5-TMB)-coated gas diffusion denuder (Huang and Hoffmann, 2008) on volcanic gases proved to be suitable to collect selectively gaseous bromine species with oxidation states of +1 or 0 (Br2 and BrO(H)), while being ignorant to HBr (OS -1). The reaction of 1,3,5-TMB with bromine gives 1-bromo-2,4,6-trimethoxybenzene (1-bromo-2,4,6-TMB) - other halogens give corresponding products. The diffusion denuder technique allows sampling of gaseous compounds exclusively without collecting particulate matter. Choosing a flow rate of 500 mL-min-1 and a denuder length of 0.5 m a nearly quantitative collection efficiency was achieved. Solvent elution of the derivatized analytes and subsequent analysis with gas chromatography

  15. Thin layer chromatography residue applicator sampler

    DOEpatents

    Nunes, Peter J.; Kelly, Fredrick R.; Haas, Jeffrey S.; Andresen, Brian D.

    2007-07-24

    A thin layer chromatograph residue applicator sampler. The residue applicator sampler provides for rapid analysis of samples containing high explosives, chemical warfare, and other analyses of interest under field conditions. This satisfied the need for a field-deployable, small, hand-held, all-in-one device for efficient sampling, sample dissolution, and sample application to an analytical technique. The residue applicator sampler includes a sampling sponge that is resistant to most chemicals and is fastened via a plastic handle in a hermetically sealed tube containing a known amount of solvent. Upon use, the wetted sponge is removed from the sealed tube and used as a swiping device across an environmental sample. The sponge is then replaced in the hermetically sealed tube where the sample remains contained and dissolved in the solvent. A small pipette tip is removably contained in the hermetically sealed tube. The sponge is removed and placed into the pipette tip where a squeezing-out of the dissolved sample from the sponge into the pipette tip results in a droplet captured in a vial for later instrumental analysis, or applied directly to a thin layer chromatography plate for immediate analysis.

  16. Analytical chromatography. Methods, instrumentation and applications

    NASA Astrophysics Data System (ADS)

    Yashin, Ya I.; Yashin, A. Ya

    2006-04-01

    The state-of-the-art and the prospects in the development of main methods of analytical chromatography, viz., gas, high performance liquid and ion chromatographic techniques, are characterised. Achievements of the past 10-15 years in the theory and general methodology of chromatography and also in the development of new sorbents, columns and chromatographic instruments are outlined. The use of chromatography in the environmental control, biology, medicine, pharmaceutics, and also for monitoring the quality of foodstuffs and products of chemical, petrochemical and gas industries, etc. is considered.

  17. Assessment of ultra high performance supercritical fluid chromatography as a separation technique for the analysis of seized drugs: Applicability to synthetic cannabinoids.

    PubMed

    Breitenbach, Stephanie; Rowe, Walter F; McCord, Bruce; Lurie, Ira S

    2016-04-01

    The recent development of modern methods for ultra high performance supercritical fluid chromatography (UHPSFC) has great potential for impacting the analysis of seized drugs. In the separation of synthetic cannabinoids the technique has the potential to produce superior resolution of positional isomers and diastereomers. To demonstrate this potential we have examined the capability of UHPSFC for the analysis of two different groups of synthetic cannabinoids. The first group was a mixture of 22 controlled synthetic cannabinoids, and the second group included JWH018 and nine of its non-controlled positional isomers The clear superiority of UHPSFC over other separation techniques was demonstrated, in that it was capable of near baseline separation of all 10 positional isomers using a chiral column. In total we examined four achiral columns, including Acquity UPC(2) Torus 2-PIC, Acquity UPC(2) Torus Diol, Acquity UPC(2) Torus DEA and Acquity UPC(2) Torus 1-AA (1.7μm 3.0×100mm), and three chiral columns, including Acquity UPC(2) Trefoil AMY1, Acquity UPC(2) Trefoil CEL1 and Acquity UPC(2) Trefoil CEL2 (2.5μm 3.0×150mm), using mobile phase compositions that combined carbon dioxide with methanol, acetonitrile, ethanol or isopropanol modifier gradients. Detection was performed using simultaneous PDA UV detection and quadrupole mass spectrometry. The orthogonality of UHPSFC, GC and UHPLC for the analysis of these compounds was demonstrated using principal component analysis. Overall we feel that this new technique should prove useful in the analysis and detection of seized drug samples, and will be a useful addition to the compendium of methods for drug analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Basic Principles of Planar Chromatography and Its Potential for Hyphenated Techniques

    NASA Astrophysics Data System (ADS)

    Tuzimski, Tomasz

    Sample preparation, detection, identification, and quantitative determination of biomolecules are presented in this chapter. Advantages of planar chromatography and the basic principles (chambers, sample application, and chromatogram development) are also described. Rapid detection of biomolecules plays a strategical role in their investigation. Hyphenated techniques such as planar chromatography coupled to UV diode array detection and to mass spectrometry provide on-line extensive structural information on the metabolites prior to their isolation. In this chapter, the combination of thin-layer chromatography (TLC) with biomolecules specific detection by diode array scanning (DAD), mass spectrometry (MS), nuclear magnetic resonance (NMR), and Fourier transform infrared spectroscopy (TLC-FTIR) is discussed. In the last part of the chapter, the reader will gain useful information about a recent method of planar chromatography - multidimensional planar chromatography (MD-PC) and information on application of different modes of multidimensional planar chromatography and combination of this technique with diode array detection (MD-PC-DAD) and HPLC-DAD for separation, detection, and qualitative and quantitative determination of biomolecules. Planar chromatography as a pilot technique for HPLC is also described.

  19. Application of automated serial blood sampling and dried blood spot technique with liquid chromatography-tandem mass spectrometry for pharmacokinetic studies in mice.

    PubMed

    Wong, Philip; Pham, Roger; Whitely, Carl; Soto, Marcus; Salyers, Kevin; James, Christopher; Bruenner, Bernd A

    2011-11-01

    The goal of this work was to obtain full pharmacokinetic profiles from individual mice with the use of an automated blood sampling system and dried blood spot (DBS) technique. AMG 517, a potent and selective vanilloid receptor (VR1) antagonist, was dosed to mice (n=3) intravenously and blood samples were collected using the automated blood sampling system with the "no blood waste" method. The collected blood samples were a mixture of 25 μL blood and 50 μL of heparinized saline solution. Two 15 μL aliquots were manually spotted onto a DBS card and dried at room temperature for at least 2h before being stored in zip bags with desiccant. The remaining samples (45 μL) were stored at -70°C until analysis. Both the DBS and the whole blood samples (diluted with saline (1:2, v/v)) were extracted and analyzed by liquid chromatography-tandem mass spectrometry. The overall extraction recovery of the analyte from the dried blood spots was determined to be about 90%. The pharmacokinetic parameters calculated using the whole blood or the DBS concentration data were comparable, and were obtained from only 3 mice, whereas conventional sampling and analysis would have required up to 27 mice to achieve the same result. The analyte was shown to be stable in the diluted whole blood (blood:saline 1:2) at room temperature for at least 4h and in the DBS for at least 34 days when stored at room temperature. These results indicated that the automated blood sampling system and DBS collection are promising techniques to obtain full pharmacokinetic profiles from individual mice and reduce the use of animals. Copyright © 2011. Published by Elsevier B.V.

  20. Application of a simple column-switching ion chromatography technique for removal of matrix interferences and sensitive fluorescence determination of acidic compounds (pharmaceutical drugs) in complex samples.

    PubMed

    Muhammad, Nadeem; Subhani, Qamar; Wang, Fenglian; Guo, Dandan; Zhao, Qiming; Wu, Shuchao; Zhu, Yan

    2017-09-15

    This work illustrates the introduction of a simple, rugged and flexible column-switching ion chromatography (IC) technique for an automated on-line QuEChERS extracted samples extracts washing followed by sensitive fluorescence (FLD) determination of five acidic pharmaceutical drugs namely; clofibric acid (CLO), ibuprofen (IBU), aspirin (ASP), naproxen (NAP) and flurobrofen (FLU) in three complex samples (spinach, apple and hospital sewage sludge). An old anion exchange column IonPac(®) AS11-HC was utilized as a pre-treatment column for on-line washing of inorganic and organic interferences followed by isocratic separation of five acidic drugs with another anion exchange IonPac(®) AS12A analytical column by exploiting the column-switching technique. This novel method exhibited good linearity with correlation coefficients (r(2)) for all drugs were in the range 0.976-0.996. The limit of detection and quantification of all five acidic drugs were in the range 0.024μg/kg to 8.70μg/kg and 0.082μg/kg to 0.029mg/kg, respectively, and better recoveries in the range 81.17-112.5% with percentage relative standard deviations (RSDs) less than 17.8% were obtained. This on-line sample pre-treatment method showed minimum matrix effect in the range of 0.87-1.25 except for aspirin. This simple rugged and flexible column-switching system required only 28min for maximum elimination of matrices and interferences in three complex samples extracts, isocratic separation of five acidic drugs and for the continuous regeneration of pre-treatment column prior to every subsequent analysis. Finally, this simple automated IC system was appeared so rugged and flexible, which can eliminate and wash out most of interference, impurities and matrices in complex samples, simply by adjusting the NaOH and acetonitrile concentration in washing mobile phase with maximum recoveries of acidic analytes of interest. Copyright © 2017. Published by Elsevier B.V.

  1. Ion-Exchange Chromatography: Basic Principles and Application.

    PubMed

    Cummins, Philip M; Rochfort, Keith D; O'Connor, Brendan F

    2017-01-01

    Ion-Exchange Chromatography (IEC) allows for the separation of ionizable molecules on the basis of differences in charge properties. Its large sample-handling capacity, broad applicability (particularly to proteins and enzymes), moderate cost, powerful resolving ability, and ease of scale-up and automation have led to it becoming one of the most versatile and widely used of all liquid chromatography (LC) techniques. In this chapter, we review the basic principles of IEC, as well as the broader criteria for selecting IEC conditions. By way of further illustration, we outline basic laboratory protocols to partially purify a soluble serine peptidase from bovine whole brain tissue, covering crude tissue extract preparation through to partial purification of the target enzyme using anion-exchange chromatography. Protocols for assaying total protein and enzyme activity in both pre- and post-IEC fractions are also described.

  2. Application of chromatography technology in the separation of active components from nature derived drugs.

    PubMed

    Zhao, H-Y; Jiang, J-G

    2010-11-01

    Chromatography technology has been widely applied in various aspects of the pharmacy research on traditional Chinese medicine (TCM). This paper reviews literatures, published in the past decades, on the separation of active component from TCM using chromatography technology. Ultra-performance liquid chromatography (UPLC), high-speed counter-current chromatography (HSCCC), rapid resolution liquid chromatography (RRLC), supercritical fluid chromatography (SFC), affinity chromatography (AC), and bio-chromatography (BC) are introduced in detail. Compared to high performance of high-performance liquid chromatography (HPLC), analysis time and solvent loss are significantly reduced by UPLC with increase in resolution and sensitivity. Some ingredients from nature derived drugs can be separated more completely by HSCCC, which has remarkable characteristics such as low cost, simple operation and no pollution. Trace components from complex systems can be selectively and efficiently separated and purified by AC, This feature makes it effective in isolation and identification of active components of Chinese herbs. Interference of some impurities could be excluded by BC. Active ingredients that are difficult to be separated by normal method can be acquired by SFC. Currently, application of novel chromatography techniques in TCM is still in the exploratory stage and many problems, such as preparation of stationary phase and detection, need to be solved.

  3. Application of Electromigration Techniques in Environmental Analysis

    NASA Astrophysics Data System (ADS)

    Bald, Edward; Kubalczyk, Paweł; Studzińska, Sylwia; Dziubakiewicz, Ewelina; Buszewski, Bogusław

    Inherently trace-level concentration of pollutants in the environment, together with the complexity of sample matrices, place a strong demand on the detection capabilities of electromigration methods. Significant progress is continually being made, widening the applicability of these techniques, mostly capillary zone electrophoresis, micellar electrokinetic chromatography, and capillary electrochromatography, to the analysis of real-world environmental samples, including the concentration sensitivity and robustness of the developed analytical procedures. This chapter covers the recent major developments in the domain of capillary electrophoresis analysis of environmental samples for pesticides, polycyclic aromatic hydrocarbons, phenols, amines, carboxylic acids, explosives, pharmaceuticals, and ionic liquids. Emphasis is made on pre-capillary and on-capillary chromatography and electrophoresis-based concentration of analytes and detection improvement.

  4. High Performance Liquid Chromatography/Video Fluorometry. Part II. Applications.

    DTIC Science & Technology

    1981-09-30

    HIGH PERFORMANCE LIQUID CHROMATOGRAPHY /VIDEO FLUOROMETRY. PART...REP«T_N&:-ŗ/ High Performance Liquid Chromatography /Video Fluorometry» Part II. Applications« by | Dennis C./Shelly* Michael P./Vogarty and...Data EnlirtdJ REPORT DOCUMENTATION PAGE t. REPORT NUMBER 2 GOVT ACCESSION NO 4. T1TI.F (and Submit) lP-^fffsyva High Performance Liquid Chromatography

  5. Immunoaffinity chromatography: an introduction to applications and recent developments

    PubMed Central

    Moser, Annette C

    2010-01-01

    Immunoaffinity chromatography (IAC) combines the use of LC with the specific binding of antibodies or related agents. The resulting method can be used in assays for a particular target or for purification and concentration of analytes prior to further examination by another technique. This review discusses the history and principles of IAC and the various formats that can be used with this method. An overview is given of the general properties of antibodies and of antibody-production methods. The supports and immobilization methods used with antibodies in IAC and the selection of application and elution conditions for IAC are also discussed. Several applications of IAC are considered, including its use in purification, immunodepletion, direct sample analysis, chromatographic immunoassays and combined analysis methods. Recent developments include the use of IAC with CE or MS, ultrafast immunoextraction methods and the use of immunoaffinity columns in microanalytical systems. PMID:20640220

  6. Chromatography.

    ERIC Educational Resources Information Center

    Brantley, L. Reed, Sr.; Demanche, Edna L.; Klemm, E. Barbara; Kyselka, Will; Phillips, Edwin A.; Pottenger, Francis M.; Yamamoto, Karen N.; Young, Donald B.

    This booklet presents some activities on chromatography. Directions for preparing leaf pigment extracts using alcohol are given, and paper chromatography and thin-layer chromatography are described as modifications of the basic principles of chromatography. (KHR)

  7. Chromatography.

    ERIC Educational Resources Information Center

    Brantley, L. Reed, Sr.; Demanche, Edna L.; Klemm, E. Barbara; Kyselka, Will; Phillips, Edwin A.; Pottenger, Francis M.; Yamamoto, Karen N.; Young, Donald B.

    This booklet presents some activities on chromatography. Directions for preparing leaf pigment extracts using alcohol are given, and paper chromatography and thin-layer chromatography are described as modifications of the basic principles of chromatography. (KHR)

  8. Recent applications of hydrophilic interaction liquid chromatography in pharmaceutical analysis.

    PubMed

    Zhang, Qian; Yang, Feng-Qing; Ge, Liya; Hu, Yuan-Jia; Xia, Zhi-Ning

    2017-01-01

    Hydrophilic interaction liquid chromatography, an alternative liquid chromatography mode, is of particular interest in separating hydrophilic and polar ionic compounds. Compared with traditional liquid chromatography techniques, hydrophilic interaction liquid chromatography offers specific advantages mainly including: (1) relatively green and water-soluble mobile phase composition, which enhances the solubility of hydrophilic and polar ionic compounds; (2) no need for ion-pairing reagents and high content of organic solvent, which benefits mass spectrometry detection; (3) high orthogonality to reverse-phase liquid chromatography, well adapted to two-dimensional liquid chromatography for complicated samples. Therefore, hydrophilic interaction liquid chromatography has been rapidly developed in many areas over the past decades. This review summarizes the recent progress (from 2012 to July 2016) of hydrophilic interaction liquid chromatography in pharmaceutical analysis, with the focus on detecting chemical drugs in various matrices, charactering active compounds of natural products and assessing biotherapeutics through typical structure unit. Moreover, the retention mechanism and behavior of analytes in hydrophilic interaction liquid chromatography as well as some novel hydrophilic interaction liquid chromatography columns used for pharmaceutical analysis are also described.

  9. Application of coupled affinity-sizing chromatography for the detection of proteolyzed HSA-tagged proteins.

    PubMed

    London, Anne Serdakowski; Patel, Kunal; Quinn, Lisa; Lemmerer, Martin

    2015-04-01

    Coupled affinity liquid chromatography and size exclusion chromatography (ALC-SEC) is a technique that has been shown to successfully report product quality of proteins during cell expression and prior to the commencement of downstream processing chromatography steps. This method was applied to monitoring the degradation and subsequent partial remediation of a HSA-tagged protein which showed proteolysis, allowing for rapid cell line development to address this product quality dilemma. This paper outlines the novel application of this method for measuring and addressing protease-induced proteolysis.

  10. Indirect fluorometric detection techniques on thin layer chromatography and effect of ultrasound on gel electrophoresis

    SciTech Connect

    Yinfa, Ma.

    1990-12-10

    Thin-layer chromatography (TLC) is a broadly applicable separation technique. It offers many advantages over high performance liquid chromatography (HPLC), such as easily adapted for two-dimensional separation, for whole-column'' detection and for handling multiple samples, etc. However, due to its draggy development of detection techniques comparing with HPLC, TLC has not received the attention it deserves. Therefore, exploring new detection techniques is very important to the development of TLC. It is the principal of this dissertation to present a new detection method for TLC -- indirect fluorometric detection method. This detection technique is universal sensitive, nondestructive, and simple. This will be described in detail from Sections 1 through Section 5. Section 1 and 3 describe the indirect fluorometric detection of anions and nonelectrolytes in TLC. In Section 2, a detection method for cations based on fluorescence quenching of ethidium bromide is presented. In Section 4, a simple and interesting TLC experiment is designed, three different fluorescence detection principles are used for the determination of caffeine, saccharin and sodium benzoate in beverages. A laser-based indirect fluorometric detection technique in TLC is developed in Section 5. Section 6 is totally different from Sections 1 through 5. An ultrasonic effect on the separation of DNA fragments in agarose gel electrophoresis is investigated. 262 refs.

  11. Applications of resistive heating in gas chromatography: a review.

    PubMed

    Jacobs, Matthew R; Hilder, Emily F; Shellie, Robert A

    2013-11-25

    Gas chromatography is widely applied to separate, identify, and quantify components of samples in a timely manner. Increasing demand for analytical throughput, instrument portability, environmental sustainability, and more economical analysis necessitates the development of new gas chromatography instrumentation. The applications of resistive column heating technologies have been espoused for nearly thirty years and resistively heated gas chromatography has been commercially available for the last ten years. Despite this lengthy period of existence, resistively heated gas chromatography has not been universally adopted. This low rate of adoption may be partially ascribed to the saturation of the market with older convection oven technology, coupled with other analytical challenges such as sampling, injection, detection and data processing occupying research. This article assesses the advantages and applications of resistive heating in gas chromatography and discusses practical considerations associated with adoption of this technology. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. ENVIRONMENTAL APPLICATION OF GAS CHROMATOGRAPHY/ATOMIC EMISSION DETECTION

    EPA Science Inventory

    A gas chromatography/atomic emission detector (GC/AED) system has been evaluated for its applicability to environmental analysis. Detection limits, elemental response factors, and regression analysis data were determined for 58 semivolatile environmental contaminants. Detection l...

  13. ENVIRONMENTAL APPLICATION OF GAS CHROMATOGRAPHY/ATOMIC EMISSION DETECTION

    EPA Science Inventory

    A gas chromatography/atomic emission detector (GC/AED) system has been evaluated for its applicability to environmental analysis. Detection limits, elemental response factors, and regression analysis data were determined for 58 semivolatile environmental contaminants. Detection l...

  14. Simultaneous analysis for water- and fat-soluble vitamins by a novel single chromatography technique unifying supercritical fluid chromatography and liquid chromatography.

    PubMed

    Taguchi, Kaori; Fukusaki, Eiichiro; Bamba, Takeshi

    2014-10-03

    Chromatography techniques usually use a single state in the mobile phase, such as liquid, gas, or supercritical fluid. Chromatographers manage one of these techniques for their purpose but are sometimes required to use multiple methods, or even worse, multiple techniques when the target compounds have a wide range of chemical properties. To overcome this challenge, we developed a single method covering a diverse compound range by means of a "unified" chromatography which completely bridges supercritical fluid chromatography and liquid chromatography. In our method, the phase state was continuously changed in the following order; supercritical, subcritical and liquid. Moreover, the gradient of the mobile phase starting at almost 100% CO2 was replaced with 100% methanol at the end completely. As a result, this approach achieved further extension of the polarity range of the mobile phase in a single run, and successfully enabled the simultaneous analysis of fat- and water-soluble vitamins with a wide logP range of -2.11 to 10.12. Furthermore, the 17 vitamins were exceptionally separated in 4min. Our results indicated that the use of dense CO2 and the replacement of CO2 by methanol are practical approaches in unified chromatography covering diverse compounds. Additionally, this is a first report to apply the novel approach to unified chromatography, and can open another door for diverse compound analysis in a single chromatographic technique with single injection, single column and single system.

  15. Less common applications of monoliths III. Gas chromatography

    PubMed Central

    Svec, Frantisek; Kurganov, Alexander A.

    2008-01-01

    Porous polymer monoliths emerged about two decades ago. Despite this short time, they are finding applications in a variety of fields. In addition to the most common and certainly best known use of this new category of porous media as stationary phases in liquid chromatography, monolithic materials also found their applications in other areas. This review article focuses on monoliths in capillaries designed for separations in gas chromatography. PMID:17645884

  16. [Applications of fast and ultra performance liquid chromatography in the analysis of Chinese herbal medicines].

    PubMed

    Liu, Ying; Zhou, Jianliang; Li, Ping

    2009-09-01

    The analysis of chemical components of Chinese herbal medicines (CHMs) is one of the most critical issues not only for screening and analyzing the bioactive components but also for controlling their quality. However, due to the complexity of the chemical constituents of CHMs, it is difficult to separate them on column within a short time. In the recent, the fast and ultra performance liquid chromatography, including ultra high pressure liquid chromatography, high performance liquid chromatography based on the monolithic columns and high temperature liquid chromatography, are of particular interest because of the high resolution and fast analytical speed provided by these techniques. This overview covers the principle and separation characteristics of these techniques, as well as their applications in Chinese herbal medicines.

  17. Photogrammetric techniques for aerospace applications

    NASA Astrophysics Data System (ADS)

    Liu, Tianshu; Burner, Alpheus W.; Jones, Thomas W.; Barrows, Danny A.

    2012-10-01

    Photogrammetric techniques have been used for measuring the important physical quantities in both ground and flight testing including aeroelastic deformation, attitude, position, shape and dynamics of objects such as wind tunnel models, flight vehicles, rotating blades and large space structures. The distinct advantage of photogrammetric measurement is that it is a non-contact, global measurement technique. Although the general principles of photogrammetry are well known particularly in topographic and aerial survey, photogrammetric techniques require special adaptation for aerospace applications. This review provides a comprehensive and systematic summary of photogrammetric techniques for aerospace applications based on diverse sources. It is useful mainly for aerospace engineers who want to use photogrammetric techniques, but it also gives a general introduction for photogrammetrists and computer vision scientists to new applications.

  18. Halogen speciation in volcanic plumes - Development of compact denuder sampling techniques with in-situ derivatization followed by gas chromatography-mass spectrometry and their application at Mt. Etna, Mt. Nyiragongo and Mt. Nyamulagira in 2015.

    NASA Astrophysics Data System (ADS)

    Rüdiger, Julian; Bobrowski, Nicole; Hoffmann, Thorsten

    2016-04-01

    products. The diffusion denuder technique allows sampling of gaseous compounds exclusively without collecting particulate matter. Solvent elution of the derivatized analytes and subsequent analysis with gas chromatography-mass spectrometry gives a limit of detection below 1 ng of bromine. The method was applied in 2015 on volcanic gas plumes at Mt. Etna (Italy), Mt. Nyiragongo and Mt. Nyamulagira (DR Congo) giving reactive bromine mixing ratios from 0.3 ppb (Nyiragongo) up to 22 ppb (Etna, NEC). Compared with total halogen data derived by alkaline trap sampling (Raschig-tube) and ion-chromatography analysis the reactive bromine mixing ratios allow the investigation of the conversion of HBr into reactive species due to plume chemistry with progressing plume age. The new method will be described in detail and the first results on the reactive halogen to total halogen output will be discussed (for bromine and chlorine) and compared to earlier volcanic plume chemistry model studies. References Bobrowski, N. and G. Giuffrida: Bromine monoxide / sulphur dioxide ratios in relation to volcanological observations at Mt. Etna 2006-2009. Solid Earth, 3, 433-445, 2012 Bobrowski, N., R. von Glasow, A. Aiuppa, S. Inguaggiato, I. Louban, O. W. Ibrahim and U. Platt: Reactive halogen chemistry in volcanic plumes. J. Geophys. Res., 112, 2007 Donovan A., V. Tsanev, C. Oppenheimer and M. Edmonds: Reactive halogens (BrO and OClO) detected in the plume of Soufrière Hills Volcano during an eruption hiatus. Geochem. Geophys. Geosyst., 15, 3346-3363, 2014 Rüdiger, J., N. Bobrowski, T. Hoffmann (2015), Development and application of compact denuder sampling techniques with in situ derivatization followed by gas chromatography-mass spectrometry for halogen speciation in volcanic plumes (EGU2015-2392-2), EGU General Assembly 2015

  19. Applications of Electromigration Techniques: Applications of Electromigration Techniques in Food Analysis

    NASA Astrophysics Data System (ADS)

    Wieczorek, Piotr; Ligor, Magdalena; Buszewski, Bogusław

    Electromigration techniques, including capillary electrophoresis (CE), are widely used for separation and identification of compounds present in food products. These techniques may also be considered as alternate and complementary with respect to commonly used analytical techniques, such as high-performance liquid chromatography (HPLC), or gas chromatography (GC). Applications of CE concern the determination of high-molecular compounds, like polyphenols, including flavonoids, pigments, vitamins, food additives (preservatives, antioxidants, sweeteners, artificial pigments) are presented. Also, the method developed for the determination of proteins and peptides composed of amino acids, which are basic components of food products, are studied. Other substances such as carbohydrates, nucleic acids, biogenic amines, natural toxins, and other contaminations including pesticides and antibiotics are discussed. The possibility of CE application in food control laboratories, where analysis of the composition of food and food products are conducted, is of great importance. CE technique may be used during the control of technological processes in the food industry and for the identification of numerous compounds present in food. Due to the numerous advantages of the CE technique it is successfully used in routine food analysis.

  20. Recent advances in bioprocessing application of membrane chromatography.

    PubMed

    Orr, Valerie; Zhong, Luyang; Moo-Young, Murray; Chou, C Perry

    2013-01-01

    Compared to traditional chromatography using resins in packed-bed columns, membrane chromatography is a relatively new and immature bioseparation technology based on the integration of membrane filtration and liquid chromatography into a single-stage operation. Over the past decades, advances in membrane chemistry have yielded novel membrane devices with high binding capacities and improved mass transfer properties, significantly increasing the bioprocessing efficiency for purification of biomolecules. Due to the disposable nature, low buffer consumption, and reduced equipment costs, membrane chromatography can significantly reduce downstream bioprocessing costs. In this review, we discuss technological merits and disadvantages associated with membrane chromatography as well as recent bioseparation applications with a particular attention on purification of large biomolecules. Copyright © 2013 Elsevier Inc. All rights reserved.

  1. Use of Chromatography Techniques to Separate a Mixture of Substances

    ERIC Educational Resources Information Center

    Donaldson, W.

    1976-01-01

    Explains the separation of the constituents of mixtures on one piece of chromatography paper. The example presented involves a vitamin C tablet, a disprin tablet, and a glucose tablet. Outlined are two methods for separating the constituents. (GS)

  2. Use of Chromatography Techniques to Separate a Mixture of Substances

    ERIC Educational Resources Information Center

    Donaldson, W.

    1976-01-01

    Explains the separation of the constituents of mixtures on one piece of chromatography paper. The example presented involves a vitamin C tablet, a disprin tablet, and a glucose tablet. Outlined are two methods for separating the constituents. (GS)

  3. A practical strategy for characterization of the metabolic profile of chiral drugs using combinatory liquid chromatography-mass spectrometric techniques: application to tetrahydropalmatine enantiomers and their metabolites in rat urine.

    PubMed

    Zhang, Yinying; Dong, Xin; Le, Jian; Wen, Jun; Lin, Zebin; Liu, Yinli; Lou, Ziyang; Chai, Yifeng; Hong, Zhanying

    2014-06-01

    The characterization and quantification of the metabolites of chiral drugs still remain a great challenge due to the complexity of the metabolites and most of them are not commercially available. In this study, a practical approach based on the combinatory liquid chromatography-mass spectrometric techniques has been proposed for the evaluation of metabolism profiles and urinary excretion kinetics of chiral drugs and their metabolites. Racemic tetrahydropalmatine (rac-THP), a biologically active ingredient isolated from a traditional Chinese herb Rhizoma Corydalis, was chosen as the model chiral drug. Ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS) was applied to characterize the metabolites of THP enantiomers in rat urine after administration of (+)-THP or (-)-THP. Accurate mass measurement was used to determine the elemental composition of metabolites and thus to confirm the proposed structures of these metabolites. More than 30 potential metabolites were found in rat urine, most of which were identified for the first time, and the metabolic pathways in vivo were involved in demethylation, oxidation, glucuronide conjugation and sulfation, etc. And the tridesmethlyzed metabolite and didesmethlyzed coupled with oxidation metabolite were found only in (+)-THP treated rats. Afterwards, a liquid chromatography tandem mass spectrometry (LC-QqQ/MS) assay was developed and validated for the determination of the urine level of THP enantiomers and their metabolites. Semi-quantification of three phase I metabolites and two phase II metabolites were performed. Enantiomeric (-/+) cumulative urinary excretion ratios of THP and its five metabolites were obtained, which indicated the stereoselective aspects of metabolites of THP enantiomers in vivo. The study demonstrated the enormous potential of this strategy for the qualitative characterization, quantitative assay and the stereoselectivity of chiral drugs and their

  4. An Application of Trimethylsilyl Derivatives with Temperature Programmed Gas Chromatography to the Senior Analytical Laboratory.

    ERIC Educational Resources Information Center

    Kelter, Paul B.; Carr, James D.

    1983-01-01

    Describes an experiment designed to teach temperature programed gas chromatography (TPGC) techniques and importance of derivatizing many classes of substrated to be separated. Includes equipment needed, procedures for making trimethylsilyl derivatives, applications, sample calculations, and typical results. Procedure required one, three-hour…

  5. An Application of Trimethylsilyl Derivatives with Temperature Programmed Gas Chromatography to the Senior Analytical Laboratory.

    ERIC Educational Resources Information Center

    Kelter, Paul B.; Carr, James D.

    1983-01-01

    Describes an experiment designed to teach temperature programed gas chromatography (TPGC) techniques and importance of derivatizing many classes of substrated to be separated. Includes equipment needed, procedures for making trimethylsilyl derivatives, applications, sample calculations, and typical results. Procedure required one, three-hour…

  6. Gas Chromatography.

    ERIC Educational Resources Information Center

    Karasek, Francis W.; And Others

    1984-01-01

    This review covers fundamental developments in gas chromatography during 1982 and 1983. Literature is considered under these headings: columns; liguid phases; solid supports; sorption processes and solvents; open tubular column gas chromatography; instrumentation; high-resolution columns and applications; other techniques; qualitative and…

  7. Gas Chromatography.

    ERIC Educational Resources Information Center

    Karasek, Francis W.; And Others

    1984-01-01

    This review covers fundamental developments in gas chromatography during 1982 and 1983. Literature is considered under these headings: columns; liguid phases; solid supports; sorption processes and solvents; open tubular column gas chromatography; instrumentation; high-resolution columns and applications; other techniques; qualitative and…

  8. Advanced techniques for energy-efficient industrial-scale continuous chromatography

    SciTech Connect

    DeCarli, J.P. II ); Carta, G. . Dept. of Chemical Engineering); Byers, C.H. )

    1989-11-01

    Continuous annular chromatography (CAC) is a developing technology that allows truly continuous chromatographic separations. Previous work has demonstrated the utility of this technology for the separation of various materials by isocratic elution on a bench scale. Novel applications and improved operation of the process were studied in this work, demonstrating that CAC is a versatile apparatus which is capable of separations at high throughput. Three specific separation systems were investigated. Pilot-scale separations at high loadings were performed using an industrial sugar mixture as an example of scale-up for isocratic separations. Bench-scale experiments of a low concentration metal ion mixture were performed to demonstrate stepwise elution, a chromatographic technique which decreases dilution and increases sorbent capacity. Finally, the separation of mixtures of amino acids by ion exchange was investigated to demonstrate the use of displacement development on the CAC. This technique, which perhaps has the most potential, when applied to the CAC allowed simultaneous separation and concentration of multicomponent mixtures on a continuous basis. Mathematical models were developed to describe the CAC performance and optimize the operating conditions. For all the systems investigated, the continuous separation performance of the CAC was found to be very nearly the same as the batchwise performance of conventional chromatography. the technology appears, thus, to be very promising for industrial applications. 43 figs., 9 tabs.

  9. Profiling degradants of paclitaxel using liquid chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry substructural techniques.

    PubMed

    Volk, K J; Hill, S E; Kerns, E H; Lee, M S

    1997-08-15

    A rapid and systematic strategy based on liquid chromatography-mass spectrometry (LC-MS) profiling and liquid chromatography-tandem mass spectrometry (LC-MS-MS) substructural techniques was utilized to elucidate the degradation products of paclitaxel, the active ingredient in Taxol. This strategy integrates, in a single instrumental approach, analytical HPLC, UV detection, full-scan electrospray MS, and MS-MS to rapidly and accurately elucidate structures of impurities and degradants. In these studies, degradants induced by acid, base, peroxide, and light were profiled using LC-MS and LC-MS-MS methodologies resulting in an LC-MS degradant database which includes information on molecular structures, chromatographic behavior, molecular mass, and MS-MS substructural information. The stressing conditions which may cause drug degradation are utilized to validate the analytical monitoring methods and serve as predictive tools for future formulation and packaging studies. Degradation products formed upon exposure to basic conditions included baccatin III, paclitaxel sidechain methyl ester, 10-deacetylpaclitaxel, and 7-epipaclitaxel. Degradation products formed upon exposure to acidic conditions included 10-deacetylpaclitaxel and the oxetane ring opened product. Treatment with hydrogen peroxide produced only 10-deacetylpaclitaxel. Exposure to high intensity ligh produced a number of degradants. The most abundant photodegradant of paclitaxel corresponded to an isomer which contains a C3-C11 bridge. These methodologies are applicable at any stage of the drug product cycle from discovery through development. This library of paclitaxel degradants provides a foundation for future development work regarding product monitoring, as well as use as a diagnostic tool for new degradation products.

  10. Novel fire investigation technique using needle extraction in gas chromatography.

    PubMed

    Ueta, Ikuo; Saito, Yoshihiro; Teraoka, Kenta; Matsuura, Hisashi; Fujimura, Koji; Jinno, Kiyokatsu

    2010-01-01

    A novel fire investigation technique using a needle extraction device was studied. Using a polymer particle-packed needle device, air samples containing volatile organic compounds (VOCs) generated from fire accelerants, gasoline and kerosene were extracted effectively, and subsequent gas chromatographic (GC) analyses were successfully carried out. Carpet and wood samples were spiked with gasoline and kerosene, followed by monitoring of the time-variation profiles of emitted VOCs up to 48 h. The fire accelerants were also measured for combusted carpet and wood samples, and the applicability of the proposed method to fire investigations was confirmed. Even at 48 h after spiking, groups of characteristic compounds were clearly observed in the air environments near the combusted sample. This method was further applied to the determination of VOCs in simulated fires, strongly suggesting the applicability of the developed method to real fire investigations.

  11. Application of gas chromatography to analysis of spirit-based alcoholic beverages.

    PubMed

    Wiśniewska, Paulina; Śliwińska, Magdalena; Dymerski, Tomasz; Wardencki, Waldemar; Namieśnik, Jacek

    2015-01-01

    Spirit-based beverages are alcoholic drinks; their production processes are dependent on the type and origin of raw materials. The composition of this complex matrix is difficult to analyze, and scientists commonly choose gas chromatography techniques for this reason. With a wide selection of extraction methods and detectors it is possible to provide qualitative and quantitative analysis for many chemical compounds with various functional groups. This article describes different types of gas chromatography techniques and their most commonly used associated extraction techniques (e.g., LLE, SPME, SPE, SFE, and SBME) and detectors (MS, TOFMS, FID, ECD, NPD, AED, O or EPD). Additionally, brief characteristics of internationally popular spirit-based beverages and application of gas chromatography to the analysis of selected alcoholic drinks are presented.

  12. Fuzzy mathematical techniques with applications

    SciTech Connect

    Kandel, A.

    1986-01-01

    This text presents the basic concepts of fuzzy set theory within a context of real-world applications. The book is self-contained and can be used as a starting point for people interested in this fast growing field as well as by researchers looking for new application techniques. The section on applications includes: Manipulation of knowledge in expert systems; relational database structures; pattern clustering; analysis of transient behavior in digital systems; modeling of uncertainty and search trees. Contents: Fuzzy sets; Possibility theory and fuzzy quantification; Fuzzy functions; Fuzzy events and fuzzy statistics; Fuzzy relations; Fuzzy logics; Some applications; Bibliography.

  13. Data compression techniques and applications

    NASA Astrophysics Data System (ADS)

    Benelli, G.; Cappellini, V.; Lotti, F.

    1980-02-01

    The paper reviews several data compression methods for signal and image digital processing and transmission, including both established and more recent techniques. Attention is also given to methods of prediction-interpolation, differential pulse code modulation, delta modulation and transformations. The processing of two dimensional data is also considered, and the results of the application of these techniques to space telemetry and biomedical digital signal processing and telemetry systems are presented.

  14. Chromatography

    MedlinePlus

    Chromatography is a way of separating two or more chemical compounds. Chemical compounds are chemicals that are ... of chemical compound. There are different kinds of chromatography. These include gas, high pressure liquid, or ion ...

  15. Applications of hydrophilic interaction chromatography to amino acids, peptides, and proteins.

    PubMed

    Periat, Aurélie; Krull, Ira S; Guillarme, Davy

    2015-02-01

    This review summarizes the recent advances in the analysis of amino acids, peptides, and proteins using hydrophilic interaction chromatography. Various reports demonstrate the successful analysis of amino acids under such conditions. However, a baseline resolution of the 20 natural amino acids has not yet been published and for this reason, there is often a need to use mass spectrometry for detection to further improve selectivity. Hydrophilic interaction chromatography is also recognized as a powerful technique for peptide analysis, and there are a lot of papers showing its applicability for proteomic applications (peptide mapping). It is expected that its use for peptide mapping will continue to grow in the future, particularly because this analytical strategy can be combined with reversed-phase liquid chromatography, in a two-dimensional setup, to reach very high resolving power. Finally, the interest in hydrophilic interaction chromatography for intact proteins analysis is less evident due to possible solubility issues and a lack of suitable hydrophilic interaction chromatography stationary phases. To date, it has been successfully employed only for the characterization of membrane proteins, histones, and the separation of glycosylated isoforms of an intact glycoprotein. From our point of view, the number of hydrophilic interaction chromatography columns compatible with intact proteins (higher upper temperature limit, large pore size, etc.) is still too limited. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Application of ion chromatography in pharmaceutical and drug analysis.

    PubMed

    Jenke, Dennis

    2011-08-01

    Ion chromatography (IC) has developed and matured into an important analytical methodology in a number of diverse applications and industries, including pharmaceuticals. This manuscript provides a review of IC applications for the determinations of active and inactive ingredients, excipients, degradation products, and impurities relevant to pharmaceutical analyses and thus serves as a resource for investigators looking for insights into the use of the IC methodology in this field of application.

  17. Characterisation of poly(vinyl alcohol) by liquid chromatography techniques

    SciTech Connect

    Meehan, E.; Warner, F.P.; Patterson, M.

    1995-12-01

    The molecular weight distribution of poly (vinyl alcohol) can be measured by aqueous size exclusion chromatography methods but the choice of eluent is critical in eliminating non size exclusion behavior. Aqueous size exclusion experiments have been carried out using a number of eluents including standard electrolytes and surfactants. The most favorable molecular size separation was obtained using 0.25% w/v sodium lauryl sulphate as eluent. Compositional distributions in copolymer systems can be assessed using high performance liquid chromatography employing a reverse phase separation mechanism. For poly (vinyl alcohol) gradient elution with water/tetrahydrofuran was found to produce a separation according to composition. Fast gradient elution (>10% tetrahydrofuran/minute) suggested abroad distribution of composition which was verified using a column packed with non-porous beads. Slower gradient elution (<1% tetrahydrofuran/minute) suggested that this was not due to a gradual composition change but rather discrete fractions of similarly hydrophobic material.

  18. multiplex gas chromatography: A novel analytical technique for future planetary studies

    NASA Technical Reports Server (NTRS)

    Valentin, J. R.; Carle, G. C.; Phillips, J. B.

    1986-01-01

    Determination of molecular species comprised of the biogenic elements in the atmospheres of planets and moons of the solar system is one the foremost requirements of the exobiologist studying chemical evolution and the origin of life. Multiplex chromatography is a technique where many samples are pseudo-randomly introduced to the chromatograph without regard to elution of preceding components. The resulting data are then reduced using mathematical techniques such as cross correlation or Fourier Transforms. To demonstrate the utility of this technique for future solar system exploration, chemical modulators were developed. Several advantages were realized from this technique in combination with these modulators: improvement in detection limits of several orders of magnitude, improvement in the analysis of complex mixtures by selectively modulating some of the components present in the sample, increase in the number of analyses that can be conducted in a given period of time, and reduction in the amount of expendables needed to run an analysis. In order to apply this technique in a real application, methane in ambient air was monitored continuously over a period of one week. By using ambient air as its own carrier all expendables beyond power were eliminated.

  19. Review of online coupling of sample preparation techniques with liquid chromatography.

    PubMed

    Pan, Jialiang; Zhang, Chengjiang; Zhang, Zhuomin; Li, Gongke

    2014-03-07

    Sample preparation is still considered as the bottleneck of the whole analytical procedure, and efforts has been conducted towards the automation, improvement of sensitivity and accuracy, and low comsuption of organic solvents. Development of online sample preparation techniques (SP) coupled with liquid chromatography (LC) is a promising way to achieve these goals, which has attracted great attention. This article reviews the recent advances on the online SP-LC techniques. Various online SP techniques have been described and summarized, including solid-phase-based extraction, liquid-phase-based extraction assisted with membrane, microwave assisted extraction, ultrasonic assisted extraction, accelerated solvent extraction and supercritical fluids extraction. Specially, the coupling approaches of online SP-LC systems and the corresponding interfaces have been discussed and reviewed in detail, such as online injector, autosampler combined with transport unit, desorption chamber and column switching. Typical applications of the online SP-LC techniques have been summarized. Then the problems and expected trends in this field are attempted to be discussed and proposed in order to encourage the further development of online SP-LC techniques.

  20. Applications of liquid chromatography--mass spectrometry in analytical toxicology: a review.

    PubMed

    Hoja, H; Marquet, P; Verneuil, B; Lotfi, H; Pénicaut, B; Lachâtre, G

    1997-01-01

    Liquid chromatography-mass spectrometry (LC-MS), after long-term development that has introduced seven major interfacing techniques, is finally suitable for application in the field of analytical toxicology. Various compound classes can be analyzed, and sensitivities for more or less polar analytes that are as good as or better than those of gas chromatography-mass spectrometry can be obtained with modern interfaces. In addition, because ionization is often softer than classical electron impact, some LC-MS interfaces are able to handle fragile species that are otherwise not amenable to MS. This review is intended to present LC-MS to less familiarized readers and to give an extensive overview of the application of the different coupling techniques to doping agents, drugs of abuse, forensic analysis, toxic compounds of various nature, and several toxicologically relevant therapeutic drugs. Experimental parameters such as the interfaces used, ionization methods, detection limits, and experimental details for exemplary applications are given.

  1. Use and application of hydrophobic interaction chromatography for protein purification.

    PubMed

    McCue, Justin T

    2014-01-01

    The objective of this section is to provide the reader with guidelines and background on the use and experimental application of Hydrophobic Interaction chromatography (HIC) for the purification of proteins. The section will give step by step instructions on how to use HIC in the laboratory to purify proteins. General guidelines and relevant background information is also provided.

  2. Neptunium(III) application in extraction chromatography.

    PubMed

    Guérin, Nicolas; Nadeau, Kenny; Larivière, Dominic

    2011-12-15

    This paper describes a novel strategy for actinide separation by extraction chromatography with Np(III) valence adjustment. Neptunium(IV) was reduced to Np(III) using Cr(II) and then selectively separated from uranium (IV) on a TEVA resin. After elution, Np(III) was retained on a DGA resin in order to remove any detrimental chromium impurities. Neptunium(III) formation was demonstrated by the complete and selective elution of Np from TEVA resin (99 ± 7%) in less than 12 mL of 9M HCl from U(IV) (0.7 ± 0.7%). It was determined by UV-visible and kinetic studies that Cr(II) was the only species responsible for the elution of Np(IV) as Np(III) and that the Cr(II) solution could be prepared from 2 to 30 min before its use without the need of complex degassing systems to prevent the oxidation of Np(III) by oxygen. The methodology proposed here with TEVA/DGA resins provides removal of Cr(III) impurities produced at high decontamination factors (2.8 × 10(3) and 7.3 × 10(4) respectively). Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Application of an online ion chromatography-based instrument ...

    EPA Pesticide Factsheets

    In North America, the dry component of total nitrogen and sulfur deposition remains uncertain due to a lack of measurements of sufficient chemical speciation and temporal extent to develop complete annual mass budgets or of sufficient process level detail to improve current air-surface exchange models. Over the past decade, significant advances have been made in the development of continuous chemical measurement techniques with sufficient sensitivity and temporal resolution to directly quantify air-surface exchange of nitrogen and sulfur compounds. However, their applicability is generally restricted to only one or a few of the compounds within the deposition budget. We characterize for the first time the performance of the Monitor for AeRosols and GAses in ambient air (MARGA), an on-line ion chromatography-based analyzer, as applied for air-surface exchange measurements of HNO3, NH3, NH4+, NO3-, SO2 and SO42-. Analytical accuracy and precision are assessed under field conditions and total uncertainty of fluxes measured by the aerodynamic gradient method are assessed for a representative 3-week period in the fall of 2012. During this period, percentages of hourly chemical gradients larger than the corresponding gradient detection limit were 86%, 55%, 81%, 74%, 77%, and 71% for NH3, NH4+, HNO3, NO3-, SO2, and SO42-, respectively. As expected, percentages were lowest for aerosol species, owing to their relatively low deposition velocities and correspondingly sma

  4. Application of an online ion chromatography-based instrument ...

    EPA Pesticide Factsheets

    In North America, the dry component of total nitrogen and sulfur deposition remains uncertain due to a lack of measurements of sufficient chemical speciation and temporal extent to develop complete annual mass budgets or of sufficient process level detail to improve current air-surface exchange models. Over the past decade, significant advances have been made in the development of continuous chemical measurement techniques with sufficient sensitivity and temporal resolution to directly quantify air-surface exchange of nitrogen and sulfur compounds. However, their applicability is generally restricted to only one or a few of the compounds within the deposition budget. We characterize for the first time the performance of the Monitor for AeRosols and GAses in ambient air (MARGA), an on-line ion chromatography-based analyzer, as applied for air-surface exchange measurements of HNO3, NH3, NH4+, NO3-, SO2 and SO42-. Analytical accuracy and precision are assessed under field conditions and total uncertainty of fluxes measured by the aerodynamic gradient method are assessed for a representative 3-week period in the fall of 2012. During this period, percentages of hourly chemical gradients larger than the corresponding gradient detection limit were 86%, 55%, 81%, 74%, 77%, and 71% for NH3, NH4+, HNO3, NO3-, SO2, and SO42-, respectively. As expected, percentages were lowest for aerosol species, owing to their relatively low deposition velocities and correspondingly sma

  5. Analysis of Biological Interactions by Affinity Chromatography: Clinical and Pharmaceutical Applications.

    PubMed

    Hage, David S

    2017-06-01

    The interactions between biochemical and chemical agents in the body are important in many clinical processes. Affinity chromatography and high-performance affinity chromatography (HPAC), in which a column contains an immobilized biologically related binding agent, are 2 methods that can be used to study these interactions. This review presents various approaches that can be used in affinity chromatography and HPAC to characterize the strength or rate of a biological interaction, the number and types of sites that are involved in this process, and the interactions between multiple solutes for the same binding agent. A number of applications for these methods are examined, with an emphasis on recent developments and high-performance affinity methods. These applications include the use of these techniques for fundamental studies of biological interactions, high-throughput screening of drugs, work with modified proteins, tools for personalized medicine, and studies of drug-drug competition for a common binding agent. The wide range of formats and detection methods that can be used with affinity chromatography and HPAC for examining biological interactions makes these tools attractive for various clinical and pharmaceutical applications. Future directions in the development of small-scale columns and the coupling of these methods with other techniques, such as mass spectrometry or other separation methods, should continue to increase the flexibility and ease with which these approaches can be used in work involving clinical or pharmaceutical samples. © 2016 American Association for Clinical Chemistry.

  6. Simultaneous quantification of chrysophanol and physcion in rat plasma by ultra fast liquid chromatography-tandem mass spectrometry and application of the technique to comparative pharmacokinetic studies of Radix et Rhei Rhizoma extract alone and Dahuang Fuzi Decoction.

    PubMed

    Liu, Xiao; Li, Huan; Wu, Li; Xing, Jiangwa; Poh, Yanhong; Cai, Hao; Cai, Bao Chang

    2015-02-01

    Most herbal medicines are prescribed in combination based on the theory of TCM to obtain synergistic effects or diminish the possible adverse reactions. Compatibility refers to the combination of two or more herbs based on the clinical settings and the properties of herbs. Chrysophanol and physcion are the main effective compounds in Radix et Rhizoma Rhei and Dahuang Fuzi Decoction which is the combination of Radix et Rhizoma Rhei, Radix Aconiti Lateralis Praeparata and Radix et Rhizoma Asari. However, chrysophanol and physcion are difficult to detect in vivo because of their low concentration and interference from endogenous compounds. The aim of this study is to develop a rapid, specific and sensitive ultra high performance liquid chromatography-triple quadrupole tandem mass method to simultaneously quantify chrysophanol and physcion in rat plasma, in order to better understand the pharmacokinetics and compatibility mechanism of Dahuang Fuzi Decoction for the first time. Multiple reaction monitoring (MRM) mode was applied for the quantitation at [M-H](-)m/z 253.0→m/z 225.1 for chrysophanol, [M-H](-) for m/z 283.1→m/z 240.0 physcion and [M-H](-)m/z 239.0→m/z 211.0 for IS. The analytes were separated on an Agilent Eclipse plus C18 column (100mm×2.1mm, 1.8μm) column within a total running time of 6.5min using a mixture of 3mM ammonium acetate in water and methanol (95:5, v/v) with a time program flow gradient according to the "plus gradient chromatography" theory. The inclusion of the ammonium acetate in the UFLC mobile phase dramatically improved the detection limit of the tested compounds and decreased the interference by matrix effects, which have been referred to as "LC-electrolyte effects". Finally, we demonstrated the application of a validated method in a comparative pharmacokinetic study of rats receiving an oral dose of Dahuang Fuzi Decoction or Radix et Rhei Rhizoma, the monarch drug in the prescription. Pharmacokinetic parameters showed

  7. Diamond based adsorbents and their application in chromatography.

    PubMed

    Peristyy, Anton A; Fedyanina, Olga N; Paull, Brett; Nesterenko, Pavel N

    2014-08-29

    The idea of using diamond and diamond containing materials in separation sciences has attracted a strong interest in the past decade. The combination of a unique range of properties, such as chemical inertness, mechanical, thermal and hydrolytic stability, excellent thermal conductivity with minimal thermal expansion and intriguing adsorption properties makes diamond a promising material for use in various modes of chromatography. This review summarises the recent research on the preparation of diamond and diamond based stationary phases, their properties and chromatographic performance. Special attention is devoted to the dominant retention mechanisms evident for particular diamond containing phases, and their subsequent applicability to various modes of chromatography, including chromatography carried out under conditions of high temperature and pressure. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Efficient purification of paclitaxel from yews using high-performance displacement chromatography technique.

    PubMed

    Watchueng, Jean; Kamnaing, Pierre; Gao, Jin-Ming; Kiyota, Taira; Yeboah, Faustinus; Konishi, Yasuo

    2011-05-20

    Paclitaxel was purified using high-performance displacement chromatography (HPDC) technique, but not by the mechanism of HPDC. On small scale, paclitaxel was extracted with methanol from dry needles of Taxus canadensis and was enriched by extracting with chloroform after removing water-soluble hydrophilic components and hexane-soluble hydrophobic components. Then, 93-99% purity of paclitaxel was obtained using the HPDC technique. On large scale, taxanes were enriched by solvent partitioning between acetic acid/MeOH/H(2)O and hexane and extracted with CH(2)Cl(2). Taxanes except paclitaxel were further removed by extracting with methanol-water-trifluoroacetic acid (1.0:98.9:0.1, v/v/v). Applying HPDC technique to water-insoluble substances is problematic as this method requires a highly aqueous solvent system. In order to overcome this incompatibility, a system was set up where paclitaxel, although in low concentration, was extracted by methanol-water-trifluoroacetic acid (10.0:89.9:0.1, v/v/v). Recycling the extracting solvent to ensure minimal volume, the extracted paclitaxel was adsorbed on a C(18) trap column. A C(18) column of 4.6mm internal diameter was then connected to the trap column. The HPDC technique was thus carried out using an isocratic acetonitrile-water-trifluoroacetic acid (30.0:69.9:0.1, v/v/v) mobile phase consisting of a displacer cetylpyridinium trifluoroacetate (3mg/mL). Paclitaxel was co-eluted with the displacer and spontaneously crystallized. The crystal (114mg) showed 99.4% purity and only 10% of paclitaxel in the starting crude extract was lost during the enrichment/purification processes. This large scale purification method was successfully applied to purify paclitaxel from Chinese yew in small scale, suggesting general applicability of the method. This is the first report of purifying a water-insoluble natural product using HPDC technique.

  9. Pinch technique: Theory and applications

    NASA Astrophysics Data System (ADS)

    Binosi, Daniele; Papavassiliou, Joannis

    2009-08-01

    We review the theoretical foundations and the most important physical applications of the Pinch Technique (PT). This general method allows the construction of off-shell Green’s functions in non-Abelian gauge theories that are independent of the gauge-fixing parameter and satisfy ghost-free Ward identities. We first present the diagrammatic formulation of the technique in QCD, deriving, at one loop, the gauge independent gluon self-energy, quark-gluon vertex, and three-gluon vertex, together with their Abelian Ward identities. The generalization of the PT to theories with spontaneous symmetry breaking is carried out in detail, and the profound connection with the optical theorem and the dispersion relations are explained within the electroweak sector of the Standard Model. The equivalence between the PT and the Feynman gauge of the Background Field Method (BFM) is elaborated, and the crucial differences between the two methods are critically scrutinized. A variety of field theoretic techniques needed for the generalization of the PT to all orders are introduced, with particular emphasis on the Batalin-Vilkovisky quantization method and the general formalism of algebraic renormalization. The main conceptual and technical issues related to the extension of the technique beyond one loop are described, using the two-loop construction as a concrete example. Then the all-order generalization is thoroughly examined, making extensive use of the field theoretic machinery previously introduced; of central importance in this analysis is the demonstration that the PT-BFM correspondence persists to all orders in perturbation theory. The extension of the PT to the non-perturbative domain of the QCD Schwinger-Dyson equations is presented systematically, and the main advantages of the resulting self-consistent truncation scheme are discussed. A plethora of physical applications relying on the PT are finally reviewed, with special emphasis on the definition of gauge

  10. Recent progress and applications of ion-exclusion/ion-exchange chromatography for simultaneous determination of inorganic anions and cations.

    PubMed

    Nakatani, Nobutake; Kozaki, Daisuke; Mori, Masanobu; Tanaka, Kazuhiko

    2012-01-01

    One of the ultimate goals of ion chromatography is to determine both anions and cations found in samples with a single chromatographic run. In the present article, recent progress in ion-exclusion/ion-exchange chromatography for the simultaneous determinations of inorganic anions and cations are reviewed. Firstly, the principle and the control for the simultaneous separation and detection of analyte ions using ion-exclusion/cation-exchange chromatography with a weakly acidic cation-exchange column are outlined. Then, advanced chromatographic techniques in terms of analytical time, selectively and sensitivity are summarized. As a related method, ion-exclusion/anion-exchange chromatography with an anion-exchange column could be used for the simultaneous determination of inorganic nitrogen species, such as ammonium, nitrite and nitrate ions. Their usefulness and applications to water-quality monitoring and related techniques are also described.

  11. Developments in the application of gas chromatography with atomic emission (plus mass spectrometric) detection.

    PubMed

    van Stee, L L P; Brinkman, U A Th

    2008-04-04

    Capillary gas chromatography with atomic emission detection is a highly element-selective and sensitive detection technique for many non-metal as well as metallic elements. A 3-5 order of magnitude element/carbon selectivity, compound-independent calibration and the possibility to calculate (partial) molecular formulae are some of the attractive features of the technique. In the present review, the emphasis is on real-life applications for non-metals such as sulphur, phosphorus, nitrogen and the halogens, and on the potential of combined atomic emission/mass spectrometric detection.

  12. Ultrasound Techniques for Space Applications

    NASA Technical Reports Server (NTRS)

    Rooney, James A.

    1985-01-01

    Ultrasound has proven to be a safe non-invasive technique for imaging organs and measuring cardiovascular function. It has unique advantages for application to problems with man in space including evaluation of cardiovascular function both in serial studies and during critical operations. In addition, specialized instrumentation may be capable of detecting the onset of decompression sickness during EVA activities. A spatial location and three-dimensional reconstruction system is being developed to improve the accuracy and reproducibility for serial comparative ultrasound studies of cardiovascular function. The three-dimensional method permits the acquisition of ultrasonic images from many views that can be recombined into a single reconstruction of the heart or vasculature. In addition to conventional imaging and monitoring systems, it is sometimes necessary or desirable to develop instrumentation for special purposes. One example of this type of development is the design of a pulsed-Doppler system to monitor cerebral blood flow during critical operations such as re-entry. A second example is the design of a swept-frequency ultrasound system for the detection of bubbles in the circulatory system and/or soft tissues as an early indication of the onset of decompression sickness during EVA activities. This system exploits the resonant properties of bubbles and can detect both fundamental and second harmonic emissions from the insonified region.

  13. Ultrasound Techniques for Space Applications

    NASA Technical Reports Server (NTRS)

    Rooney, James A.

    1985-01-01

    Ultrasound has proven to be a safe non-invasive technique for imaging organs and measuring cardiovascular function. It has unique advantages for application to problems with man in space including evaluation of cardiovascular function both in serial studies and during critical operations. In addition, specialized instrumentation may be capable of detecting the onset of decompression sickness during EVA activities. A spatial location and three-dimensional reconstruction system is being developed to improve the accuracy and reproducibility for serial comparative ultrasound studies of cardiovascular function. The three-dimensional method permits the acquisition of ultrasonic images from many views that can be recombined into a single reconstruction of the heart or vasculature. In addition to conventional imaging and monitoring systems, it is sometimes necessary or desirable to develop instrumentation for special purposes. One example of this type of development is the design of a pulsed-Doppler system to monitor cerebral blood flow during critical operations such as re-entry. A second example is the design of a swept-frequency ultrasound system for the detection of bubbles in the circulatory system and/or soft tissues as an early indication of the onset of decompression sickness during EVA activities. This system exploits the resonant properties of bubbles and can detect both fundamental and second harmonic emissions from the insonified region.

  14. High-performance thin layer chromatography: A powerful analytical technique in pharmaceutical drug discovery

    PubMed Central

    Attimarad, Mahesh; Ahmed, K. K. Mueen; Aldhubaib, Bandar E.; Harsha, Sree

    2011-01-01

    Analysis of pharmaceutical and natural compounds and newer drugs is commonly used in all the stages of drug discovery and development process. High-performance thin layer chromatography is one of the sophisticated instrumental techniques based on the full capabilities of thin layer chromatography. The advantages of automation, scanning, full optimization, selective detection principle, minimum sample preparation, hyphenation, and so on enable it to be a powerful analytical tool for chromatographic information of complex mixtures of pharmaceuticals, natural products, clinical samples, food stuffs, and so on. PMID:23781433

  15. Aerospace management techniques: Commercial and governmental applications

    NASA Technical Reports Server (NTRS)

    Milliken, J. G.; Morrison, E. J.

    1971-01-01

    A guidebook for managers and administrators is presented as a source of useful information on new management methods in business, industry, and government. The major topics discussed include: actual and potential applications of aerospace management techniques to commercial and governmental organizations; aerospace management techniques and their use within the aerospace sector; and the aerospace sector's application of innovative management techniques.

  16. Basic Principles of Chromatography

    NASA Astrophysics Data System (ADS)

    Ismail, Baraem; Nielsen, S. Suzanne

    Chromatography has a great impact on all areas of analysis and, therefore, on the progress of science in general. Chromatography differs from other methods of separation in that a wide variety of materials, equipment, and techniques can be used. [Readers are referred to references (1-19) for general and specific information on chromatography.]. This chapter will focus on the principles of chromatography, mainly liquid chromatography (LC). Detailed principles and applications of gas chromatography (GC) will be discussed in Chap. 29. In view of its widespread use and applications, high-performance liquid chromatography (HPLC) will be discussed in a separate chapter (Chap. 28). The general principles of extraction are first described as a basis for understanding chromatography.

  17. Viability of Applying Curie Point Pyrolysis/Gas Chromatography Techniques for Characterization of Ammonium Perchlorate Based Propellants

    SciTech Connect

    BARNETT, JAMES L.; MONTOYA, BERTHA M.

    2002-07-01

    Curie Point pyrolysis-gas chromatography was investigated for use as a tool for characterization of aged ammonium perchlorate based composite propellants (1). Successful application of the technique will support the surveillance program for the Explosives Materials and Subsystems Department (1). Propellant samples were prepared by separating the propellant into reacted (oxidated) and unreacted zones. The experimental design included the determination of system reliability followed by, reproducibility, sample preparation and analysis of pyrolysis products. Polystyrene was used to verify the reliability of the system and showed good reproducibility. Application of the technique showed high variation in the data. Modifications to sample preparation did not enhance the reproducibility. It was determined that the high concentration of ammonium perchlorate in the propellant matrix was compromising the repeatability of the analysis.

  18. Liquid chromatography and supercritical fluid chromatography as alternative techniques to gas chromatography for the rapid screening of anabolic agents in urine.

    PubMed

    Desfontaine, Vincent; Nováková, Lucie; Ponzetto, Federico; Nicoli, Raul; Saugy, Martial; Veuthey, Jean-Luc; Guillarme, Davy

    2016-06-17

    This work describes the development of two methods involving supported liquid extraction (SLE) sample treatment followed by ultra-high performance liquid chromatography or ultra-high performance supercritical fluid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS and UHPSFC-MS/MS) for the screening of 43 anabolic agents in human urine. After evaluating different stationary phases, a polar-embedded C18 and a diol columns were selected for UHPLC-MS/MS and UHPSFC-MS/MS, respectively. Sample preparation, mobile phases and MS conditions were also finely tuned to achieve highest selectivity, chromatographic resolution and sensitivity. Then, the performance of these two methods was compared to the reference routine procedure for steroid analyses in anti-doping laboratories, which combines liquid-liquid extraction (LLE) followed by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). For this purpose, urine samples spiked with the compounds of interest at five different concentrations were analyzed using the three analytical platforms. The retention and selectivity of the three techniques were very different, ensuring a good complementarity. However, the two new methods displayed numerous advantages. The overall procedure was much faster thanks to high throughput SLE sample treatment using 48-well plates and faster chromatographic analysis. Moreover, the highest sensitivity was attained using UHPLC-MS/MS with 98% of the doping agents detected at the lowest concentration level (0.1ng/mL), against 76% for UHPSFC-MS/MS and only 14% for GC-MS/MS. Finally, the weakest matrix effects were obtained with UHPSFC-MS/MS with 76% of the analytes displaying relative matrix effect between -20 and 20%, while the GC-MS/MS reference method displayed very strong matrix effects (over 100%) for all of the anabolic agents. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Serial displacement chromatofocusing and its applications in multidimensional chromatography and gel electrophoresis: II. Experimental results.

    PubMed

    Shen, Hong; Li, Xiang; Bieberich, Charles; Frey, Douglas D

    2009-02-06

    Part I of this study investigated the theory and basic characteristics of "serial displacement chromatofocusing" (SDC). In Part II of this study, SDC is applied to two prototype applications which have potential uses in proteomics and related areas involving the analysis of complex analyte mixtures. In the first application, SDC was used as a prefractionation method prior to two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) to separate a human prostate cancer cell lysate. It was observed that the resolution achieved in narrow-pI-range 2D-PAGE was improved when using SDC prefractionation, so that SDC may be useful as a low-cost, high-speed, and highly scalable alternative to electrophoretic prefractionation methods for 2D-PAGE. The second application involves the use of SDC as the first dimension, and reversed-phase chromatography as the second dimension, to produce a novel, fully automated, two-dimensional high-performance liquid chromatography technique. The method was shown to have performance advantages over one-dimensional reversed-phase chromatography for peptide separations.

  20. Separation of mAbs molecular variants by analytical hydrophobic interaction chromatography HPLC: overview and applications.

    PubMed

    Haverick, Mark; Mengisen, Selina; Shameem, Mohammed; Ambrogelly, Alexandre

    2014-01-01

    Hydrophobic interaction chromatography-high performance liquid chromatography (HIC-HPLC) is a powerful analytical method used for the separation of molecular variants of therapeutic proteins. The method has been employed for monitoring various post-translational modifications, including proteolytic fragments and domain misfolding in etanercept (Enbrel®); tryptophan oxidation, aspartic acid isomerization, the formation of cyclic imide, and α amidated carboxy terminus in recombinant therapeutic monoclonal antibodies; and carboxy terminal heterogeneity and serine fucosylation in Fc and Fab fragments. HIC-HPLC is also a powerful analytical technique for the analysis of antibody-drug conjugates. Most current analytical columns, methods, and applications are described, and critical method parameters and suitability for operation in regulated environment are discussed, in this review.

  1. Low thermal mass gas chromatography: principles and applications.

    PubMed

    Luong, Jim; Gras, Ronda; Mustacich, Robert; Cortes, Hernan

    2006-01-01

    In gas chromatography (GC), temperature programming is often considered to be the second most important parameter to control, the first being column selectivity. A radically new GC technology to achieve ultrafast temperature programming with an unprecedented cool down time and low power consumption has recently become available. This technology is referred to as low thermal mass GC (LTMGC). Though the technology has its roots in resistive heating, which forms the basis of principle and design concept, the approach taken to achieve ultrafast heating and cool down time by LTMGC represents a significant break-through in GC. Despite some rectifiable shortcomings, LTMGC has proven to be an ideal methodology to deliver near/real time GC data, high precision, and high throughput applications. It is a new approach for modern high-speed GC. This paper documents the fundamental design principles behind LTMGC, performance data, and examples of applications investigated.

  2. Inkjet application, chromatography, and mass spectrometry of sugars on nanostructured thin films.

    PubMed

    Kirchert, Simone; Wang, Zhen; Taschuk, Michael T; Jim, Steven R; Brett, Michael J; Morlock, Gertrud E

    2013-09-01

    Ultrathin-layer chromatography (UTLC) potentially offers faster analysis, reduced solvent and sample volumes, and lower costs. One novel technique for producing UTLC plates has been glancing angle deposition (GLAD), a physical vapor deposition technique capable of aligning macropores to produce interesting separation properties. To date, however, GLAD-UTLC plates have been restricted to model dye systems, rather than realistic analytes. This study demonstrates the transfer of high-performance thin-layer chromatography (HPTLC) sugar analysis methods to GLAD-UTLC plates using the office chromatography framework. A consumer inkjet printer was used to apply very sharp low volume (3-30 nL) bands of water-soluble analytes (lactose, sucrose, and fructose). Analytic performance measurements extrapolated the limits of detection to be 3-5 ng/zone, which was experimentally proven down to 60-70 ng/band, depending on the sugar. This qualitative analysis of sugars in a commercially available chocolate sample is the first reported application of GLAD-UTLC to food samples. The potential utility of GLAD-UTLC is further exemplified by successful coupling with electrospray ionization mass spectrometry for the first time to characterize underivatized sugars.

  3. Liquid chromatography/tandem mass spectrometry of unusual phenols from Yucca schidigera bark: comparison with other analytical techniques.

    PubMed

    Montoro, Paola; Piacente, Sonia; Oleszek, Wieslaw; Pizza, Cosimo

    2004-10-01

    Qualitative and quantitative analyses of phenolic compounds are of interest for both medicinal and food plants. In the present work, the phenolic fraction from Yucca schidigera, a plant bearing the GRAS (Generally Recognized as Safe) label approved by the US Food and Drug Administration, was studied. Crude extracts of Y. schidigera bark were investigated by liquid chromatography/UV spectrophotometry with diode-array detection, liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS) and liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS), in order to develop and optimize simple and rapid techniques to determine both stilbenes and yuccaols for the purposes of quality control of collected material. With optimal LC and MS conditions, stilbenes and yuccaols were quantified with all the proposed methods and the results were compared. Sensitivity was evaluated and the results indicated that MS/MS detection in the multiple reaction monitoring mode is easily applicable to this plant and allows the rapid and direct identification and quantification of these peculiar compounds in crude plant extracts.

  4. High-pressure liquid chromatography: A brief introduction and its application in analyzing the degradation of a C-ether (Thio-ether) liquid lubricant

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The general principles of classical liquid chromatography and high pressure liquid chromatography (HPLC) are reviewed, and their advantages and disadvantages are compared. Several chromatographic techniques are reviewed, and the analytical separation of a C-ether liquid lubricant by each technique is illustrated. A practical application of HPLC is then demonstrated by analyzing a degraded C-ether liquid lubricant from full scale, high temperature bearing tests.

  5. High Performance Thin Layer Chromatography.

    ERIC Educational Resources Information Center

    Costanzo, Samuel J.

    1984-01-01

    Clarifies where in the scheme of modern chromatography high performance thin layer chromatography (TLC) fits and why in some situations it is a viable alternative to gas and high performance liquid chromatography. New TLC plates, sample applications, plate development, and instrumental techniques are considered. (JN)

  6. High Performance Thin Layer Chromatography.

    ERIC Educational Resources Information Center

    Costanzo, Samuel J.

    1984-01-01

    Clarifies where in the scheme of modern chromatography high performance thin layer chromatography (TLC) fits and why in some situations it is a viable alternative to gas and high performance liquid chromatography. New TLC plates, sample applications, plate development, and instrumental techniques are considered. (JN)

  7. Ion beam analysis techniques in interdisciplinary applications

    SciTech Connect

    Respaldiza, Miguel A.; Ager, Francisco J.

    1999-11-16

    The ion beam analysis techniques emerge in the last years as one of the main applications of electrostatic accelerators. A short summary of the most used IBA techniques will be given as well as some examples of applications in interdisciplinary sciences.

  8. Ion Beam Analysis Techniques in Interdisciplinary Applications

    SciTech Connect

    Respaldiza, Miguel A.; Ager, Francisco J.

    1999-12-31

    The ion beam analysis techniques emerge in the last years as one of the main applications of electrostatic accelerators. A short summary of the most used IBA techniques will be given as well as some examples of applications in interdisciplinary sciences.

  9. ELECTRICAL TECHNIQUES FOR ENGINEERING APPLICATIONS.

    USGS Publications Warehouse

    Bisdorf, Robert J.

    1985-01-01

    Surface electrical geophysical methods have been used in such engineering applications as locating and delineating shallow gravel deposits, depth to bedrock, faults, clay zones, and other geological phenomena. Other engineering applications include determining water quality, tracing ground water contaminant plumes and locating dam seepages. Various methods and electrode arrays are employed to solve particular geological problems. The sensitivity of a particular method or electrode array depends upon the physics on which the method is based, the array geometry, the electrical contrast between the target and host materials, and the depth to the target. Each of the available electrical methods has its own particular advantages and applications which the paper discusses.

  10. Microfluidic liquid chromatography system for proteomic applications and biomarker screening.

    PubMed

    Lazar, Iulia M; Trisiripisal, Phichet; Sarvaiya, Hetal A

    2006-08-01

    A microfluidic liquid chromatography (LC) system for proteomic investigations that integrates all the necessary components for stand-alone operation, i.e., pump, valve, separation column, and electrospray interface, is described in this paper. The overall size of the LC device is small enough to enable the integration of two fully functional separation systems on a 3 in. x 1 in. glass microchip. A multichannel architecture that uses electroosmotic pumping principles provides the necessary functionality for eluent propulsion and sample valving. The flow rates generated within these chips are fully consistent with the requirements of nano-LC platforms that are routinely used in proteomic applications. The microfluidic device was evaluated for the analysis of a protein digest obtained from the MCF7 breast cancer cell line. The cytosolic protein extract was processed according to a shotgun protocol, and after tryptic digestion and prefractionation using strong cation exchange chromatography (SCX), selected sample subfractions were analyzed with conventional and microfluidic LC platforms. Using similar experimental conditions, the performance of the microchip LC was comparable to that obtained with benchtop instrumentation, providing an overlap of 75% in proteins that were identified by more than two unique peptides. The microfluidic LC analysis of a protein-rich SCX fraction enabled the confident identification of 77 proteins by using conventional data filtering parameters, of 39 proteins with p < 0.001, and of 5 proteins that are known to be cancer-specific biomarkers, demonstrating thus the potential applicability of these chips for future high-throughput biomarker screening applications.

  11. Application of ultraperformance liquid chromatography/mass spectrometry-based metabonomic techniques to analyze the joint toxic action of long-term low-level exposure to a mixture of organophosphate pesticides on rat urine profile.

    PubMed

    Du, Longfei; Wang, Hong; Xu, Wei; Zeng, Yan; Hou, Yurong; Zhang, Yuqiu; Zhao, Xiujuan; Sun, Changhao

    2013-07-01

    In previously published articles, we evaluated the toxicity of four organophosphate (OP) pesticides (dichlorvos, dimethoate, acephate, and phorate) to rats using metabonomic technology at their corresponding no observed adverse effect level (NOAEL). Results show that a single pesticide elicits no toxic response. This study aimed to determine whether chronic exposure to a mixture of the above four pesticides (at their corresponding NOAEL) can lead to joint toxic action in rats using the same technology. Pesticides were administered daily to rats through drinking water for 24 weeks. The above mixture of the four pesticides showed joint toxic action at the NOAEL of each pesticide. The metabonomic profiles of rats urine were analyzed by ultraperformance liquid chromatography/mass spectrometry. The 16 metabolites statistically significantly changed in all treated groups compared with the control group. Dimethylphosphate and dimethyldithiophosphate exclusively detected in all treated groups can be used as early, sensitive biomarkers for exposure to a mixture of the OP pesticides. Moreover, exposure to the OP pesticides resulted in increased 7-methylguanine, ribothymidine, cholic acid, 4-pyridoxic acid, kynurenine, and indoxyl sulfate levels, as well as decreased hippuric acid, creatinine, uric acid, gentisic acid, C18-dihydrosphingosine, phytosphingosine, suberic acid, and citric acid. The results indicated that a mixture of OP pesticides induced DNA damage and oxidative stress, disturbed the metabolism of lipids, and interfered with the tricarboxylic acid cycle. Ensuring food safety requires not only the toxicology test data of each pesticide for the calculation of the acceptable daily intake but also the joint toxic action.

  12. Recent Advance in Liquid Chromatography/Mass Spectrometry Techniques for Environmental Analysis in Japan

    PubMed Central

    Suzuki, Shigeru

    2014-01-01

    The techniques and measurement methods developed in the Environmental Survey and Monitoring of Chemicals by Japan’s Ministry of the Environment, as well as a large amount of knowledge archived in the survey, have led to the advancement of environmental analysis. Recently, technologies such as non-target liquid chromatography/high resolution mass spectrometry and liquid chromatography with micro bore column have further developed the field. Here, the general strategy of a method developed for the liquid chromatography/mass spectrometry (LC/MS) analysis of environmental chemicals with a brief description is presented. Also, a non-target analysis for the identification of environmental pollutants using a provisional fragment database and “MsMsFilter,” an elemental composition elucidation tool, is presented. This analytical method is shown to be highly effective in the identification of a model chemical, the pesticide Bendiocarb. Our improved micro-liquid chromatography injection system showed substantially enhanced sensitivity to perfluoroalkyl substances, with peak areas 32–71 times larger than those observed in conventional LC/MS. PMID:26819891

  13. Electrochemically-modulated liquid chromatography (EMLC): Column design, retention processes, and applications

    SciTech Connect

    Ting, En -Yi

    1997-10-08

    This work describes the continued development of a new separation technique, electrochemically-modulated liquid chromatography (EMLC), from column design, retention mechanisms to pharmaceutical applications. The introduction section provides a literature review of the technique as well as a brief overview of the research in each of the chapters. This section is followed by four chapters which investigate the issues of EMLC column design, the retention mechanism of monosubstituted aromatic compounds, and the EMLC-based applications to two important classes of pharmaceutical compounds (i.e., corticosteroids and benzodiazepines). These four sections have been removed to process separately for inclusion on the database. The dissertation concludes with a general summary, a prospectus, and a list of references cited in the General Introduction. 32 refs.

  14. Chemical characterization of α-pinene secondary organic aerosol constituents using gas chromatography, liquid chromatography, and paper spray-based mass spectrometry techniques.

    PubMed

    Rindelaub, Joel D; Wiley, Joshua S; Cooper, Bruce R; Shepson, Paul B

    2016-07-15

    Despite ample research into the atmospheric oxidation of α-pinene, an important precursor to biogenic secondary organic aerosol formation, the identification of its reaction products, specifically organic nitrates, which impact atmospheric NOx concentrations, is still incomplete. This negatively impacts our understanding of α-pinene oxidation chemistry and its relation to air quality. Photochemical chamber experiments were conducted in conjunction with mass spectrometric techniques, including gas chromatography/mass spectrometry (GC/MS), high-performance liquid chromatography/time-of-flight (HPLC/TOF), and paper spray ionization MS, to investigate products from the OH radical initiated oxidation of α-pinene under high NOx conditions. Over 30 compounds were tentatively identified, including those newly detected from photochemical chamber studies of α-pinene oxidation, pinocamphenol, fencholenic aldehyde, and α-pinene-derived nitrate isomers. α-Pinene-derived hydroxynitrate isomers were successfully detected using chromatographic methods, demonstrating, for the first time, the identification of individual first-generation organic nitrate products derived from α-pinene. The application of paper spray ionization to particle-phase compounds collected on filters represents a novel method for the direct analysis of filter samples at ambient pressure and temperature. The use of HPLC/TOF and paper spray ionization methods to identify previously unobserved α-pinene-derived products helps lower the uncertainty in α-pinene oxidation chemistry and provides new platforms that can be used to identify and quantify important atmospheric compounds that relate to air quality in a complex sample matrix, such as ambient aerosol particles. Additionally, the use of paper spray ionization for direct filter analysis is a fast, relatively inexpensive sample preparation technique that can be used to reduce sample manipulation from solvent-induced reactions. Copyright © 2016 John

  15. Thin-Layer and Paper Chromatography.

    ERIC Educational Resources Information Center

    Sherma, Joseph; Fried, Bernard

    1984-01-01

    Reviews literature on chromatography examining: books, reviews, student experiments; chromatographic systems, techniques, apparatus; detecting and identification of separated zones; preparative chromatography and radiochromatography; and applications related to specific materials (such as acids, alcohols, amino acids, antibiotics, enzymes, dyes,…

  16. Thin-Layer and Paper Chromatography.

    ERIC Educational Resources Information Center

    Sherma, Joseph; Fried, Bernard

    1984-01-01

    Reviews literature on chromatography examining: books, reviews, student experiments; chromatographic systems, techniques, apparatus; detecting and identification of separated zones; preparative chromatography and radiochromatography; and applications related to specific materials (such as acids, alcohols, amino acids, antibiotics, enzymes, dyes,…

  17. Identification of Explosives from Porous Materials: Applications Using Reverse Phase High Performance Liquid Chromatography and Gas Chromatography

    NASA Astrophysics Data System (ADS)

    Miller, C. J.; Elias, G.; Schmitt, N. C.; Rae, C.

    2010-06-01

    High performance liquid chromatography and gas chromatography techniques are well documented and widely used for the detection of trace explosives from organic solvents. These techniques were modified to identify and quantify explosives extracted from various materials taken from people who had recently handled explosives. Documented techniques were modified to specifically detect and quantify trace levels of the military explosives, RDX, TNT, and PETN from denim, colored flannel, vinyl, and canvas extracted in methanol and filtered using no additional sample cleanup of the sample extract prior to analysis. The filtered methanol extracts were injected directly into several different column types and analyzed by high performance liquid chromatography using ultraviolet detection and/or gas chromatography using electron capture detection. This paper describes general screening methods that were used to determine the presence of explosives (RDX, TNT, and PETN) in unknown samples of denim, colored flannel, vinyl and canvas in addition to techniques that have been optimized for quantification of each explosive from the substrate extracts.

  18. Applications of CFD and visualization techniques

    NASA Technical Reports Server (NTRS)

    Saunders, James H.; Brown, Susan T.; Crisafulli, Jeffrey J.; Southern, Leslie A.

    1992-01-01

    In this paper, three applications are presented to illustrate current techniques for flow calculation and visualization. The first two applications use a commercial computational fluid dynamics (CFD) code, FLUENT, performed on a Cray Y-MP. The results are animated with the aid of data visualization software, apE. The third application simulates a particulate deposition pattern using techniques inspired by developments in nonlinear dynamical systems. These computations were performed on personal computers.

  19. Identification of Explosives from Porous Materials: Applications Using Reverse Phase High Performance Liquid Chromatography and Gas Chromatography

    SciTech Connect

    C.J. Miller; G. Elias; N.C. Schmitt; C. Rae

    2010-06-01

    High performance liquid chromatography and gas chromatography techniques are well documented and widely used for the detection of trace explosives from organic solvents. These techniques were modified to specifically identify and quantify explosives extracted from various materials taken from people who had recently handled explosives. Documented techniques were modified to specifically detect and quantify RDX, TNT, and PETN from denim, colored flannel, vinyl, and canvas extracted in methanol using no sample cleanup prior to analysis. The methanol extracts were injected directly into several different column types and analyzed by HPLC-UV and/or GC-ECD. This paper describes general screening methods that were used to determine the presence of explosives in unknown samples and techniques that have been optimized for quantification of each explosive from the substrate extracts.

  20. Gradient chromatography under constant frictional heat: realization and application.

    PubMed

    Gritti, Fabrice; Guiochon, Georges

    2013-05-10

    A new mode of gradient elution in liquid chromatography is proposed. It is derived from simple theoretical considerations and is particularly suitable for applications to fast, very-high pressure gradients. It is designed to improve the injection-to-injection repeatability of chromatographic runs at either constant flow (cF, cooling case scenario) or constant pressure (cP, heating case scenario). The purpose of this original gradient mode is to minimize the variations of the temperatures and the pressures across and along the column during the gradient time. These variations are caused by the heat generated in the column due to the friction of the eluent percolating the bed. Any temperature fluctuation affects to some extent the precision of the measurements of retention times and bandwidths of eluted compounds. The minimization of this effect was achieved by maintaining constant the frictional heat power (i.e., the product of the flow rate by the column pressure drop) generated during the gradient run, the washing step, and the re-equilibration time. The eluent temperature was recorded at the column outlet. One useful application of gradient chromatography at constant frictional heat (cFH) is illustrated for a 50-100% volume gradient of acetonitrile in water using a 4.6mm × 150 mm column packed with 3.5 μm BEH-C18 particles and operated with an Agilent 1290 Infinity liquid chromatograph. The reproducibility (eleven consecutive injections) of the retention times and peak variances of nine small molecules (RPLC check-out sample mixture) using cF, cP, and cFH gradients were compared for the same amount of heat produced (403 J) during each run time. The RSDs of the retention times and the peak variances for four consecutive injections were systematically below 0.035 and 0.50% in constant frictional heat gradient chromatography, after three initial injections. These RSDs were markedly higher for cF (0.050 and 0.90%) and cP (0.070 and 1.80%) gradients. Copyright

  1. Digitally enhanced thin layer chromatography: further development and some applications in isotopic chemistry.

    PubMed

    Manthorpe, Daniel P; Lockley, William J S

    2013-09-01

    Improvements to thin layer chromatography (TLC) analysis can be made easily and cheaply by the application of digital colour photography and image analysis. The combined technique, digitally enhanced TLC (DE-TLC), is applicable to the accurate quantification of analytes in mixtures, to reaction monitoring and to other typical uses of TLC. Examples are given of the application of digitally enhanced TLC to: the deuteromethylations of theophylline to [methyl-(2)H3]caffeine and of umbelliferone to [(2)H3]7-methoxycoumarin; the selection of tertiary amine bases in deuterodechlorination reactions; stoichiometry optimisation in the borodeuteride reduction of quinizarin (1,4-dihydroxyanthraquinone) and to the assessment of xanthophyll yields in Lepidium sativum seedlings grown in deuterated media. Copyright © 2013 John Wiley & Sons, Ltd.

  2. Evaluation of flash supercritical fluid chromatography and alternate sample loading techniques for pharmaceutical medicinal chemistry purifications.

    PubMed

    Miller, Larry; Mahoney, Max

    2012-08-10

    Flash chromatography is the preferred approach for small molecule purification in pharmaceutical discovery. This paper will discuss the potential for flash supercritical fluid chromatography (SFC) as an alternative technology for these purifications. It was shown that the high sample loadings seen with flash LC could also be achieved using flash SFC. The dry load injection technique greatly increases the amount of sample that can be applied to a flash SFC column while still achieving separation. Flash SFC has much lower solvent usage and higher purification productivities relative to flash LC. Product concentrations post purification were higher for flash SFC vs. flash LC, reducing the time required to isolate dry product. There still exist a number of technical details to be worked out with flash SFC, mainly around the equipment and column/cartridge technology.

  3. Urinary 19-norandrosterone purification by immunoaffinity chromatography: application to gas chromatography/combustion/isotope ratio mass spectrometric analysis.

    PubMed

    Desroches, M C; Mathurin, J C; Richard, Y; Delahaut, P; de Ceaurriz, J

    2002-01-01

    The detection of exogenous 19-norandrosterone (19-NA) in urines was investigated by using gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). 19-NA is, for the first time to our knowledge, isolated from urinary matrix by specific immunoaffinity chromatography (IAC) before analysis. The sample preparation consisted of a preliminary purification of urine by solid-phase extraction after hydrolysis by beta-glucuronidase. Unconjugated 19-NA was thus isolated by IAC and directly analysed by GC/C/IRMS. Optimisation of IAC purification was achieved and the reliability of the technique for anti-doping control is discussed.

  4. Metal-organic frameworks in chromatography.

    PubMed

    Yusuf, Kareem; Aqel, Ahmad; ALOthman, Zeid

    2014-06-27

    Metal-organic frameworks (MOFs) emerged approximately two decades ago and are the youngest class of porous materials. Despite their short existence, MOFs are finding applications in a variety of fields because of their outstanding chemical and physical properties. This review article focuses on the applications of MOFs in chromatography, including high-performance liquid chromatography (HPLC), gas chromatography (GC), and other chromatographic techniques. The use of MOFs in chromatography has already had a significant impact; however, the utilisation of MOFs in chromatography is still less common than other applications, and the number of MOF materials explored in chromatography applications is limited. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Supercritical Fluid Chromatography--Theoretical Background and Applications on Natural Products.

    PubMed

    Hartmann, Anja; Ganzera, Markus

    2015-11-01

    The use of supercritical fluid chromatography for natural product analysis as well as underlying theoretical mechanisms and instrumental requirements are summarized in this review. A short introduction focusing on the historical development of this interesting separation technique is followed by remarks on the current instrumental design, also describing possible detection modes and useable stationary phases. The overview on relevant applications is grouped based on their basic intention, may it be (semi)preparative or purely analytical. They indicate that supercritical fluid chromatography is still primarily considered for the analysis of nonpolar analytes like carotenoids, fatty acids, or terpenes. The low polarity of supercritical carbon dioxide, which is used with modifiers almost exclusively as a mobile phase today, combined with high efficiency and fast separations might explain the popularity of supercritical fluid chromatography for the analysis of these compounds. Yet, it has been shown that more polar natural products (e.g., xanthones, flavonoids, alkaloids) are separable too, with the same (if not superior) selectivity and reproducibility than established approaches like HPLC or GC.

  6. Ultrasound elastography: principles, techniques, and clinical applications.

    PubMed

    Dewall, Ryan J

    2013-01-01

    Ultrasound elastography is an emerging set of imaging modalities used to image tissue elasticity and are often referred to as virtual palpation. These techniques have proven effective in detecting and assessing many different pathologies, because tissue mechanical changes often correlate with tissue pathological changes. This article reviews the principles of ultrasound elastography, many of the ultrasound-based techniques, and popular clinical applications. Originally, elastography was a technique that imaged tissue strain by comparing pre- and postcompression ultrasound images. However, new techniques have been developed that use different excitation methods such as external vibration or acoustic radiation force. Some techniques track transient phenomena such as shear waves to quantitatively measure tissue elasticity. Clinical use of elastography is increasing, with applications including lesion detection and classification, fibrosis staging, treatment monitoring, vascular imaging, and musculoskeletal applications.

  7. Analytical Applications of Monte Carlo Techniques.

    ERIC Educational Resources Information Center

    Guell, Oscar A.; Holcombe, James A.

    1990-01-01

    Described are analytical applications of the theory of random processes, in particular solutions obtained by using statistical procedures known as Monte Carlo techniques. Supercomputer simulations, sampling, integration, ensemble, annealing, and explicit simulation are discussed. (CW)

  8. Recent advances and applications of gas chromatography vacuum ultraviolet spectroscopy.

    PubMed

    Santos, Inês C; Schug, Kevin A

    2017-01-01

    The vacuum ultraviolet spectrophotometer was developed recently as an alternative to existing gas chromatography detectors. This detector measures the absorption of gas-phase chemical species in the range of 120-240 nm, where all chemical compounds present unique absorption spectra. Therefore, qualitative analysis can be performed and quantification follows standard Beer-Lambert law principles. Different fields of application, such as petrochemical, food, and environmental analysis have been explored. Commonly demonstrated is the capability for facile deconvolution of co-eluting analytes. The concept of additive absorption for co-eluting analytes has also been advanced for classification and speciation of complex mixtures using a data treatment procedure termed time interval deconvolution. Furthermore, pseudo-absolute quantitation can be performed for system diagnosis, as well as potentially calibrationless quantitation. In this manuscript an overview of these features, the vacuum ultraviolet spectrophotometer instrumentation, and performance capabilities are given. A discussion of the applications of the vacuum ultraviolet detector is provided by describing and discussing the papers published thus far since 2014. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. PHARMACEUTICAL AND BIOMEDICAL APPLICATIONS OF AFFINITY CHROMATOGRAPHY: RECENT TRENDS AND DEVELOPMENTS

    PubMed Central

    Hage, David S.; Anguizola, Jeanethe A.; Bi, Cong; Li, Rong; Matsuda, Ryan; Papastavros, Efthimia; Pfaunmiller, Erika; Vargas, John; Zheng, Xiwei

    2012-01-01

    Affinity chromatography is a separation technique that has become increasingly important in work with biological samples and pharmaceutical agents. This method is based on the use of a biologically-related agent as a stationary phase to selectively retain analytes or to study biological interactions. This review discusses the basic principles behind affinity chromatography and examines recent developments that have occurred in the use of this method for biomedical and pharmaceutical analysis. Techniques based on traditional affinity supports are discussed, but an emphasis is placed on methods in which affinity columns are used as part of HPLC systems or in combination with other analytical methods. General formats for affinity chromatography that are considered include step elution schemes, weak affinity chromatography, affinity extraction and affinity depletion. Specific separation techniques that are examined include lectin affinity chromatography, boronate affinity chromatography, immunoaffinity chromatography, and immobilized metal ion affinity chromatography. Approaches for the study of biological interactions by affinity chromatography are also presented, such as the measurement of equilibrium constants, rate constants, or competition and displacement effects. In addition, related developments in the use of immobilized enzyme reactors, molecularly imprinted polymers, dye ligands and aptamers are briefly considered. PMID:22305083

  10. Fast centrifugal partition chromatography as a preparative-scale separation technique for citrus flavones

    USDA-ARS?s Scientific Manuscript database

    Fast centrifugal partition chromatography (FCPC) is a preparative-scale separations methodology based on the principles of counter current chromatography. Separations by FCPC are typically achieved with higher recoveries and with lower solvent use compared to conventional column chromatography. HSCP...

  11. Applications of Electromigration Techniques: Electromigration Techniques in Detection of Microorganisms

    NASA Astrophysics Data System (ADS)

    Dziubakiewicz, Ewelina; Buszewski, Bogusław

    The detection and identification of microbes is a challenge and an important aspect in many fields of our lives from medicine to bioterrorism defense. However, the analysis of such complex molecules brings a lot of questions mainly about their behavior. Bacteria are biocolloid, whose surface charge originates from the ionization of carboxyl, phosphate, or amino groups and the adsorption of ions from solution. Consequently, the charged cell wall groups determine the spontaneous formation of the electrical double layer. In this chapter application of electromigration techniques for microorganism's identification and separation are described. This approach represents the possibility to apply electromigration techniques in medical diagnosis, detection of food contamination, and sterility testing.

  12. Drying techniques for the visualisation of agarose-based chromatography media by scanning electron microscopy.

    PubMed

    Nweke, Mauryn C; Turmaine, Mark; McCartney, R Graham; Bracewell, Daniel G

    2017-03-01

    The drying of chromatography resins prior to scanning electron microscopy is critical to image resolution and hence understanding of the bead structure at sub-micron level. Achieving suitable drying conditions is especially important with agarose-based chromatography resins, as over-drying may cause artefact formation, bead damage and alterations to ultrastructural properties; and under-drying does not provide sufficient resolution for visualization under SEM. This paper compares and contrasts the effects of two drying techniques, critical point drying and freeze drying, on the morphology of two agarose based resins (MabSelect™/dw ≈85 µm and Capto™ Adhere/dw ≈75 µm) and provides a complete method for both. The results show that critical point drying provides better drying and subsequently clearer ultrastructural visualization of both resins under SEM. Under this protocol both the polymer fibers (thickness ≈20 nm) and the pore sizes (diameter ≈100 nm) are clearly visible. Freeze drying is shown to cause bead damage to both resins, but to different extents. MabSelect resin encounters extensive bead fragmentation, whilst Capto Adhere resin undergoes partial bead disintegration, corresponding with the greater extent of agarose crosslinking and strength of this resin. While freeze drying appears to be the less favorable option for ultrastructural visualization of chromatography resin, it should be noted that the extent of fracturing caused by the freeze drying process may provide some insight into the mechanical properties of agarose-based chromatography media. © 2017 The Authors. Biotechnology Journal published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. [THE TECHNIQUE OF HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY FOR SIMULTANEOUS DIAGNOSTIC OF INHERENT HYPERPLASIA OF ADRENAL GLANDS TYPE I AND II].

    PubMed

    Dutov, A A; Nikitin, D A; Lukyanova, Yu L; Shemiakina, N A

    2016-01-01

    The article considers the technique of high-performance liquid chromatography making it possible simultaneously detect cortisol, cortisone and secondary steroids in serum for consequent analysis of common reversed-phase high-performance liquid chromatography with ultraviolet under 240 nm. The liquid-liquid extraction from alkaline medium in diethyl ether The separation using column of 150x4.6 size ODS 3.5 mkm in isocratic mode. The eluent acetonitrile--0.02 M phosphate buffer pH 8.0--isopropanol (40:60:1). The application of proposed technique managed to separate cortisol, cortisone, dexamethasone, corticosterone, 11-desoxicortisol, testosterone, desoxicorticosterone, 17α-gidroxiprogesterone and androstendion in 20 minutes. The simplicity, reproducibility and sufficient selectivity and sensitivity of technique permit implement it in clinical practice for simultaneous diagnostic of inherent hyperplasia of adrenal glands type I and II.

  14. Artifical intelligence: Concepts, techniques, and applications

    SciTech Connect

    Shira, Y.; Tsujii, F.R.D.

    1985-01-01

    This book examines the fundamental concepts and various techniques involved in real-world applications of artifical intelligence, such as computer representation of problems, searching and inference mechanisms, intelligent languages, and computer representation and utilization of knowledge. It explores applications in theorem-proving, games, robotics, natural language processing, knowledge engineering, and more.

  15. Skin surface profile technique and its applications.

    PubMed

    Hatzis, J

    1991-12-01

    Synopsis In this study the 'skin surface profile'(SSP) technique and its applications are described. With this technique the SSP is replicated by means of silicone impression materials. The SSP preparations were studied by a stereomicroscope or microscopic projector. Some applications of SSP technique are as follows: a. measurement of the stratum corneum hydration, b. study of the profile of primary crests and lines, c. measurement of the primary crests reservoir available for extension, and d. estimation of the true area of the skin surface in a body region.

  16. Determination of trace level bromate and perchlorate in drinking water by ion chromatography with an evaporative preconcentration technique.

    PubMed

    Liu, Yongjian; Mou, Shifen; Heberling, Shawn

    2002-05-17

    A simple sample preconcentration technique employing microwave-based evaporation for the determination of trace level bromate and perchlorate in drinking water with ion chromatography is presented. With a hydrophilic anion-exchange column and a sodium hydroxide eluent in linear gradient, bromate and perchlorate can be determined in one injection within 35 min. Prior to ion chromatographic analysis, the drinking water sample was treated with an OnGuard-Ag cartridge to remove the superfluous chloride and concentrated 20-fold using a PTFE beaker in a domestic microwave oven for 15 min. The recoveries of the anions ranged from 94.6% for NO2- to 105.2% for F-. The detection limits for bromate, perchlorate, iodate and chlorate were 0.1, 0.2, 0.1 and 0.2 microg/l, respectively. The developed method is applicable for the quantitation of bromate and perchlorate in drinking water samples.

  17. Applying Chromatography.

    ERIC Educational Resources Information Center

    Klein, Jessie W.; Patev, Paul

    1998-01-01

    Presents three experiments to introduce students to different kinds of chromatography: (1) paper chromatography; (2) gel filtration chromatography; and (3) reverse-phase liquid chromatography. Written in the form of a laboratory manual, explanations of each of the techniques, materials needed, procedures, and a glossary are included. (PVD)

  18. Chiral cyclodextrin-modified micellar electrokinetic chromatography and chemometric techniques for green tea samples origin discrimination.

    PubMed

    Pasquini, Benedetta; Orlandini, Serena; Goodarzi, Mohammad; Caprini, Claudia; Gotti, Roberto; Furlanetto, Sandra

    2016-04-01

    Catechins and methylxanthines were determined in 92 green tea (GT) samples originating from Japan and China by using micellar electrokinetic chromatography with the addition of (2-hydroxypropyl)-β-cyclodextrin. GT samples showed high concentrations of (-)-epigallocatechin gallate and caffeine, with (-)-epigallocatechin, (-)-epicatechin gallate and (-)-epicatechin in relevant content and (+)-catechin, (-)-catechin and theobromine in much lower amounts. The amount of all the considered compounds was higher for Chinese GTs, with the exception of (-)-epicatechin gallate. Pattern recognition methods were applied to discriminate GTs according to geographical origin, which is an important factor to determine quality and reputation of a commercial tea product. Data analysis was performed by principal component analysis and hierarchical cluster analysis as exploratory techniques. Linear discriminant analysis and quadratic discriminant analysis were utilized as discrimination techniques, obtaining a very good rate of correct classification and prediction.

  19. Applications of nanomaterials in liquid chromatography: opportunities for separation with high efficiency and selectivity.

    PubMed

    Zhang, Zhengxiang; Wang, Zhiyong; Liao, Yiping; Liu, Huwei

    2006-08-01

    During recent decades, great efforts have been made to improve the chemical stability, selectivity, and separation efficiency of stationary phases in liquid chromatography. Significant progress has been achieved, especially after the introduction of nanomaterials into separation science. This review covers the applications of nanomaterials playing various roles in liquid chromatography. Future possibilities for developing nanomaterial-based stationary phases are also discussed.

  20. NMR imaging techniques and applications: A review

    NASA Astrophysics Data System (ADS)

    Bottomley, Paul A.

    1982-09-01

    Over the past ten years, a variety of techniques have been proposed and demonstrated that enable the spatial discrimination and mapping of nuclear-magnetic-resonance (NMR) signals in heterogeneous objects. These NMR imaging techniques are currently finding useful application in clinical medicine and physiological chemistry, where their noninvasive, apparently hazard-free nature, and the sensitivity of the NMR signal to the state of biological tissue, are key advantages. This article reviews the historical development, the conceptual basis, and the applications of the various NMR imaging techniques. Qualitative descriptions and illustrations of each technique and an outline of imaging instrumentation are provided. Proton NMR imaging, in medicine, of pathological states such as cancer, imaging of relaxation time, chemical shift and flow parameters, imaging of nuclei other than hydrogen, and potential hazards are discussed and demonstrated with examples.

  1. Alternative sample-introduction technique to avoid breakthrough in gradient-elution liquid chromatography of polymers.

    PubMed

    Reingruber, Eva; Bedani, Filippo; Buchberger, Wolfgang; Schoenmakers, Peter

    2010-10-15

    Gradient-elution liquid chromatography (GELC) is a powerful tool for the characterization of synthetic polymers. However, gradient-elution chromatograms often suffer from breakthrough phenomena. Breakthrough can be averted by using a sample solvent as weak as the mobile phase. However, this approach is only applicable to polymers for which a sufficiently strong solvent exists which is at the same time a weak eluent. Finding such a solvent for a given polymer can be laborious or may even be impossible. Besides, when working with comprehensive two-dimensional LC the effluent of the first dimension is the injection solvent of the second dimension. In this case, it is not possible to avoid breakthrough by adjusting the eluent strength of the second-dimension injection solvent. Therefore, another strategy to avert breakthrough has to be implemented. In this work, we successfully avoided breakthrough in GELC by mixing the mobile phase not before, but after the autosampler. This was demonstrated measuring a blend of poly(methyl methacrylate) standards with different molecular-weights as model mixture with comprehensive two-dimensional GELC×size-exclusion chromatography. The strategy is thought to be applicable to all substances with a sufficiently strong dependence of retention on mobile-phase composition. This typically applies to large molecules (synthetic and natural polymers) and allows efficient refocusing. Unretained and barely retained substances are not refocused and therefore suffer in the proposed setup from peak broadening. Copyright © 2010 Elsevier B.V. All rights reserved.

  2. Systematic comparison of static and dynamic headspace sampling techniques for gas chromatography.

    PubMed

    Kremser, Andreas; Jochmann, Maik A; Schmidt, Torsten C

    2016-09-01

    Six automated, headspace-based sample preparation techniques were used to extract volatile analytes from water with the goal of establishing a systematic comparison between commonly available instrumental alternatives. To that end, these six techniques were used in conjunction with the same gas chromatography instrument for analysis of a common set of volatile organic carbon (VOC) analytes. The methods were thereby divided into three classes: static sampling (by syringe or loop), static enrichment (SPME and PAL SPME Arrow), and dynamic enrichment (ITEX and trap sampling). For PAL SPME Arrow, different sorption phase materials were also included in the evaluation. To enable an effective comparison, method detection limits (MDLs), relative standard deviations (RSDs), and extraction yields were determined and are discussed for all techniques. While static sampling techniques exhibited sufficient extraction yields (approx. 10-20 %) to be reliably used down to approx. 100 ng L(-1), enrichment techniques displayed extraction yields of up to 80 %, resulting in MDLs down to the picogram per liter range. RSDs for all techniques were below 27 %. The choice on one of the different instrumental modes of operation (aforementioned classes) was thereby the most influential parameter in terms of extraction yields and MDLs. Individual methods inside each class showed smaller deviations, and the least influences were observed when evaluating different sorption phase materials for the individual enrichment techniques. The option of selecting specialized sorption phase materials may, however, be more important when analyzing analytes with different properties such as high polarity or the capability of specific molecular interactions. Graphical Abstract PAL SPME Arrow during the extraction of volatile analytes from the headspace of an aqueous sample.

  3. Post-column labeling techniques in amino acid analysis by liquid chromatography.

    PubMed

    Rigas, Pantelis G

    2013-10-01

    Amino acid analysis (AAA) has always presented an analytical challenge in terms of sample preparation, separation, and detection. Because of the vast number of amino acids, various separation methods have been applied taking into consideration the large differences in their chemical structures, which span from nonpolar to highly polar side chains. Numerous separation methods have been developed in the past 60 years, and impressive achievements have been made in the fields of separation, derivatization, and detection of amino acids (AAs). Among the separation methods, liquid chromatography (LC) prevailed in the AAA field using either pre-column or post-column labeling techniques in order to improve either separation of AAs or selectivity and sensitivity of AAA. Of the two approaches, the post-column technique is a more rugged and reproducible method and provides excellent AAs separation relatively free from interferences. This review considers current separations combined with post-column labeling techniques for AAA, comparison with the pre-column methods, and the strategies used to develop effective post-column methodology. The focus of the article is on LC methods coupled with post-column labeling techniques and studying the reactions to achieve optimum post-column derivatization (PCD) conditions in order to increase sensitivity and selectivity using various types of detectors (UV-Vis, fluorescence, electrochemical etc.) and illustrating the versatility of the PCD methods for practical analysis.

  4. A novel antibody immobilization and its application in immunoaffinity chromatography.

    PubMed

    Zhang, Shuoyao; Wang, Junqing; Li, Dawei; Huang, Juan; Yang, Hong; Deng, Anping

    2010-07-15

    A novel antibody immobilization and its application in immunoaffinity chromatography (IAC) were presented. Using acrylamide (AM) as monomer, ethylene glycoldimethacrylate (EGDMA) as cross-linker and bulk polymerization as synthetic method, we prepared a polymer in which the Cu(II) was embedded. The Cu(II)-embedded polymer was tested for its binding with protein. It was found that Cu(II)-embedded polymer displayed a strong binding with bovine serum albumin (BSA). At 80% of methanol, no BSA was released from Cu(II)-embedded polymer. The Cu(II)-embedded polymer was then used as a novel solid support for antibody immobilization. IAC column was prepared by immobilizing polyclonal antibody (pAb) against clenbuterol (CL) on Cu(II)-embedded polymer and packing the Cu(II)-embedded polymer-pAb into a common solid phase extraction (SPE) cartridge. Under optimal extraction conditions, the IAC column was characterized in terms of maximum binding capacity for target analyte, extraction efficiency and reusability. It was revealed that, for IAC column packed with 0.1 g of solid support immobilized with antibody, the maximum capacity for CL was 616 ng; the extraction recoveries of the column for CL from three spiked food samples were 84.4-95.2% with relative standard deviation (RSD) of 9.3-15.5%; after more than 30 times repeated usage, there was not significant loss of specific recognition. The results demonstrated the feasibility of the prepared IAC column for CL extraction. The proposed antibody immobilization method exhibiting the properties of simplicity, low cost, strong binding for target analyte, no leaching of antibody, etc., would be a very useful tool applied in the field of IAC.

  5. A novel fully automated on-line coupled liquid chromatography-gas chromatography technique used for the determination of organochlorine pesticide residues in tobacco and tobacco products.

    PubMed

    Qi, Dawei; Fei, Ting; Sha, Yunfei; Wang, Leijun; Li, Gang; Wu, Da; Liu, Baizhan

    2014-12-29

    In this study, a novel fully automated on-line coupled liquid chromatography-gas chromatography (LC-GC) technique was reported and applied for the determination of organochlorine pesticide residues (OCPs) in tobacco and tobacco products. Using a switching valve to isolate the capillary pre-column and the analytical column during the solvent evaporation period, the LC solvent can be completely removed and prevented from reaching the GC column and the detector. The established method was used to determinate the OCPs in tobacco samples. By using Florisil SPE column and employing GPC technique, polarity impurities and large molecule impurities were removed. A dynamic range 1-100ng/mL was achieved with detection limits from 1.5 to 3.3μg/kg. The method exhibited good repeatability and recoveries. This technology may provide an alternative way for trace analysis of complex samples. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. [Progress of the hydrokinetic chromatography and its application in the characterization of particulate drug delivery systems].

    PubMed

    Liu, Wei; Li, Hai-Yan; Guo, Zhen; Zhang, Ji-Wen; Sun, Li-Xin

    2011-06-01

    In the present paper, the basic principles, the device and the analytical method of the hydrodynamic chromatography (HDC) were summarized, which is most widely used in hydrokinetic chromatography. The application of the hydrodynamic chromatography in the determination of the particle size and size distribution of the particulate drug delivery system was also reviewed. The method can determine the particle size of nano- and micron-scale particulate drug delivery systems rapidly. And this method also has the advantages of economic, convenient and no damage to the samples. In summary, there will be a good prospect for the application of HDC in the determination of particle size distribution features of particulate drug delivery systems.

  7. Application of Pre-Column Labeling Liquid Chromatography for Canine Plasma-Free Amino Acid Analysis

    PubMed Central

    Azuma, Kazuo; Hirao, Yoshiko; Hayakawa, Yoshihiro; Murahata, Yusuke; Osaki, Tomohiro; Tsuka, Takeshi; Imagawa, Tomohiro; Okamoto, Yoshiharu; Ito, Norihiko

    2016-01-01

    Plasma-free amino acid (PFAA) levels are a useful metric for diagnosing cancer and providing a prognosis. However, the use of analysis of PFAA levels has been limited in the veterinary medicine field. We addressed the application of liquid chromatography (LC) using a pre-column labeling technique for analysis of canine PFAA levels. This method significantly shortened the analysis time relative to conventional methods. No diurnal fluctuations were detected at 9:00 AM in most PFAA levels, and food intake increased the levels of some PFAAs, including valine, leucine, tyrosine, phenylalanine, and proline. These results indicate that LC with pre-column labeling is useful for measuring canine PFAA levels, for which time of day and interval after food intake must be taken into consideration. PMID:26771650

  8. Comparisons of three dry application autoradiographic techniques

    SciTech Connect

    Parson, M.J.; Parker, B.C. )

    1987-06-01

    We compared three common dry application techniques applied for the first time to phytoplankton taking up water-soluble radioisotopically labeled substrates. Following incubation of live phytoplankton communities in oligotrophic, nitrogen-limited Mountain Lake, Virginia, with Carbon-14 labeled methylamine-hydrochloride, an ammomium analog, we concentrated cells on 0.8 um pore size Millipore filters, then preserved filters in liquid nitrogen, and freeze-dried. Differences in the techniques are application of stripping film, preparation of freshly prepared film by dipping loops into liquid emulsion, and dipping cover slips in liquid emulsion. Following dark-incubation and development, autoradiographs were evaluated microscopically for reproducibility, fine resolution of silver grains, background scatter, and eaes of technique.

  9. Multiresidue analysis of neonicotinoids by solid-phase extraction technique using high-performance liquid chromatography.

    PubMed

    Mohan, Chander; Kumar, Yogesh; Madan, Jyotsana; Saxena, Navneet

    2010-06-01

    For routine monitoring of pesticides, a multiresidue analysis through solid-phase extraction technique and using high-performance liquid chromatography (HPLC) in cotton seed cake (CSC) has been developed. Extraction of fortified samples was carried out with aqueous acetone under vacuum. The concentrated extract was loaded onto the solid-phase extraction units, preconditioned with acetonitrile. The extraction units were then washed with hexane and finally eluted with acetonitrile. The pesticide residues were determined using a multiresidue method by reversed-phase HPLC. The average percentage recoveries were found to range between 65.47% and 110% at spiking levels of 10 to 40 mg/kg. The method developed shows a healthy rate of recovery and can successfully be utilized for the extraction and screening of neonicotinoid residues in CSC. The detection limits for imidacloprid, acetamiprid, and thiacloprid using this method were found to be 5, 10, and 20 mg/kg, respectively.

  10. High-performance liquid chromatography and immunoassay techniques for monitoring urinary metabolites of polycyclic aromatic hydrocarbons

    SciTech Connect

    Chamberlain, V.C.

    1988-01-01

    The purpose of this research was to investigate the feasibility of using high performance liquid chromatography (HPLC) and enzyme linked immunosorbent assays (ELISA) as sensitive techniques for monitoring polycyclic aromatic hydrocarbon (PAH) metabolites in human urine. The method was tested using synthesized PAH conjugates as positive markers. Results showed that a PAH conjugate, S-(9,10-dihydro-9-hydroxy-10-phenanthryl)N-acetyl cysteine (PHONAC), present in HPLC effluent could be detected by ELISA at picomole levels, well below the sensitivity of the HPLC UV detector. Analyses of urine from mice dosed with phenanthrene demonstrated that a substance detected by HPLC which was not detected in ELISA tests was the principal phenanthrene metabolite. This substance was not hydrolysed by Beta-glucuronidase. PHONAC was detected by ELISA in mouse urine extracts subjected to HPLC.

  11. Optical tweezers technique and its applications

    NASA Astrophysics Data System (ADS)

    Guo, HongLian; Li, ZhiYuan

    2013-12-01

    Since their advent in the 1980s, optical tweezers have attracted more and more attention due to their unique non-contact and non-invasion characteristics and their wide applications in physics, biology, chemistry, medical science and nanoscience. In this paper, we introduce the basic principle, the history and typical applications of optical tweezers and review our recent experimental works on the development and application of optical tweezers technique. We will discuss in detail several technological issues, including high precision displacement and force measurement in single-trap and dual-trap optical tweezers, multi-trap optical tweezers with each trap independently and freely controlled by means of space light modulator, and incorporation of cylindrical vector optical beams to build diversified optical tweezers beyond the conventional Gaussian-beam optical tweezers. We will address the application of these optical tweezers techniques to study biophysical problems such as mechanical deformation of cell membrane and binding energy between plant microtubule and microtubule associated proteins. Finally we present application of the optical tweezers technique for trapping, transporting, and patterning of metallic nanoparticles, which can be harnessed to manipulate surface plasmon resonance properties of these nanoparticles.

  12. Applications of electrochemically-modulated liquid chromatography (EMLC): Separations of aromatic amino acids and polycyclic aromatic hydrocarbons

    SciTech Connect

    Deng, Li

    1998-03-27

    The research in this thesis explores the separation capabilities of a new technique termed electrochemically-modulated liquid chromatography (EMLC). The thesis begins with a general introduction section which provides a literature review of this technique as well as a brief background discussion of the two research projects in each of the next two chapters. The two papers which follow investigate the application of EMLC to the separation of a mixture of aromatic amino acids and of a mixture of polycyclic aromatic hydrocarbons (PAHs). The last section presents general conclusions and summarizes the thesis. References are compiled in the reference section of each chapter. The two papers have been removed for separate processing.

  13. Systematic generation of buffer systems for pH gradient ion exchange chromatography and their application.

    PubMed

    Kröner, Frieder; Hubbuch, Jürgen

    2013-04-12

    pH gradient protein separations are widely used techniques in the field of protein analytics, of which isoelectric focusing is the most well known application. The chromatographic variant, based on the formation of pH gradients in ion exchange columns is only rarely applied due to the difficulties to form controllable, linear pH gradients over a broad pH range. This work describes a method for the systematic generation of buffer compositions with linear titration curves, resulting in well controllable pH gradients. To generate buffer compositions with linear titration curves an in silico method was successfully developed. With this tool, buffer compositions for pH gradient ion exchange chromatography with pH ranges spanning up to 7.5 pH units were established and successfully validated. Subsequently, the buffer systems were used to characterize the elution behavior of 22 different model proteins in cation and anion exchange pH gradient chromatography. The results of both chromatographic modes as well as isoelectric focusing were compared to describe differences in between the methods.

  14. An overview to nano-scale analytical techniques: Nano-liquid chromatography and capillary electrochromatography.

    PubMed

    Fanali, Salvatore

    2017-08-01

    Nano-liquid chromatography (nano-LC) and CEC are microfluidic techniques mainly used for analytical purposes. They have been applied to the separation and analysis of a large number of compounds, e.g., peptides, proteins, drugs, enantiomers, antibiotics, pesticides, nutraceutical, etc. Analytes separation is carried out into capillaries containing selected stationary phase. The mobile phase is moved either by a pump (nano-LC) or by an EOF, respectively. The two tools can offer some advantages over conventional techniques, e.g., high selectivity, separation efficiency, resolution, short analysis time and consumption of low volumes of mobile phase. Flow rates in the range 50-800 nL/min are usually applied. The low flow rate reduces the chromatographic dilution increasing the mass sensitivity. Special attention must be paid in avoiding peak dispersion selecting the appropriate detector, injector and tube connection. Finally due to the low flow rate these microfluidic techniques can be easily coupled with mass spectrometry. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Further application of size-exclusion chromatography combined with small-angle X-ray scattering optics for characterization of biological macromolecules.

    PubMed

    Watanabe, Yasushi; Inoko, Yoji

    2011-02-01

    Size-exclusion chromatography (gel filtration chromatography or gel permeation chromatography) in conjunction with online synchrotron radiation solution small-angle X-ray scattering optics, absorbance, and/or refractive index detectors was further assessed by application of biological macromolecules, such as the hollow sphere protein complex, apoferritin, and a linear polysaccharide, pullulan. The net X-ray scattering patterns of the eluted 24-mer molecule of apoferritin showed the specific character for the hollow spherical shape. The chromatographic (time-resolved) X-ray scattering data of the linear polysaccharide pullulan revealed the flexible chain structure during the chromatographic separation in an aqueous solution. These further applications demonstrated that the present measurement technique will be useful for not only the determination of the radius of gyration value of less than about 10 nm and molecular weight below several hundred thousand but also for the structural characterization of the various macromolecules during the chromatography.

  16. Steam still chromatography - new application for old technology

    SciTech Connect

    Burnham, D.E.; Deubel, W.T.

    1989-03-01

    Steam still chromatography was used on two wells in the Indian Mesa field and one well in the Coyanosa field, Pecos County, Texas. The objective of using steam still chromatography was to determine the gas-oil and oil-water contacts in a fractured dolomite at the Indian Mesa field and to determine the dry gas vs. rich condensate zones in a chert conglomerate at the Coyanosa field. In the Indian Mesa field, preliminary data indicate an oil-water contact at -5360 ft. The Coyanosa well is clearly zoned with very lean gas, predominantly C/sub 1/, at the top of the reservoir and a rich condensate zone higher in C/sub 3/-C/sub 5/ nearer the bottom. Clearly, steam still chromatography is an old technology that deserves a second look in evaluating carbonate reservoirs in the Permian basin.

  17. Current medical research with the application of coupled techniques with mass spectrometry

    PubMed Central

    Kałużna-Czaplińska, Joanna

    2011-01-01

    Summary The most effective methods of analysis of organic compounds in biological fluids are coupled chromatographic techniques. Capillary gas chromatography/mass spectrometry (GC-MS) allows the most efficient separation, identification and quantification of volatile metabolites in biological fluids. Liquid chromatography-mass spectrometry (LC-MS) is especially suitable for the analysis of non-volatile and/or thermally unstable compounds. A major drawback of liquid chromatography-mass spectrometry is that no standard spectral libraries such as NIST and Wiley for GC-MS are available to facilitate the identification of unknown compounds. Moreover, the identification of potential new compounds, especially new biomarkers in LC-MS, is much more challenging than in GC-MS. Capillary electrophoresis coupled with mass spectrometry (CE-MS) has been widely used to characterize metabolomes. Capillary electrophoresis is a powerful technique for the separation of charged metabolites, offering high analyte resolution. The advantages of CE-MS are applicability for hydrophilic metabolites, robust separation efficiency and short duration of analysis. This review provides an overview of current chromatographic methods – gas chromatography – mass spectrometry, liquid chromatography – mass spectrometry and capillary electrophoresis-mass spectrometry – and their applications in current medical research. The focus is on the description of metabonomics research, strategies for biomarkers identification, medical diagnoses of diseases and research of drugs. PMID:21525822

  18. An application of gas chromatography to planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Oyama, V.

    1974-01-01

    A gas chromatography developed for the Viking experiment is described. The instrument is designed to measure gases in planetary atmospheres and head space in a chamber. It is hoped that the chromatograph will also measure any biological activity present in these environments.

  19. Microextraction techniques coupled to liquid chromatography with mass spectrometry for the determination of organic micropollutants in environmental water samples.

    PubMed

    Padrón, Ma Esther Torres; Afonso-Olivares, Cristina; Sosa-Ferrera, Zoraida; Santana-Rodríguez, José Juan

    2014-07-16

    Until recently, sample preparation was carried out using traditional techniques, such as liquid-liquid extraction (LLE), that use large volumes of organic solvents. Solid-phase extraction (SPE) uses much less solvent than LLE, although the volume can still be significant. These preparation methods are expensive, time-consuming and environmentally unfriendly. Recently, a great effort has been made to develop new analytical methodologies able to perform direct analyses using miniaturised equipment, thereby achieving high enrichment factors, minimising solvent consumption and reducing waste. These microextraction techniques improve the performance during sample preparation, particularly in complex water environmental samples, such as wastewaters, surface and ground waters, tap waters, sea and river waters. Liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS) and time-of-flight mass spectrometric (TOF/MS) techniques can be used when analysing a broad range of organic micropollutants. Before separating and detecting these compounds in environmental samples, the target analytes must be extracted and pre-concentrated to make them detectable. In this work, we review the most recent applications of microextraction preparation techniques in different water environmental matrices to determine organic micropollutants: solid-phase microextraction SPME, in-tube solid-phase microextraction (IT-SPME), stir bar sorptive extraction (SBSE) and liquid-phase microextraction (LPME). Several groups of compounds are considered organic micropollutants because these are being released continuously into the environment. Many of these compounds are considered emerging contaminants. These analytes are generally compounds that are not covered by the existing regulations and are now detected more frequently in different environmental compartments. Pharmaceuticals, surfactants, personal care products and other chemicals are considered micropollutants. These compounds must be

  20. Microfluidic desalination techniques and their potential applications.

    PubMed

    Roelofs, S H; van den Berg, A; Odijk, M

    2015-09-07

    In this review we discuss recent developments in the emerging research field of miniaturized desalination. Traditionally desalination is performed to convert salt water into potable water and research is focused on improving performance of large-scale desalination plants. Microfluidic desalination offers several new opportunities in comparison to macro-scale desalination, such as providing a platform to increase fundamental knowledge of ion transport on the nano- and microfluidic scale and new microfluidic sample preparation methods. This approach has also lead to the development of new desalination techniques, based on micro/nanofluidic ion-transport phenomena, which are potential candidates for up-scaling to (portable) drinking water devices. This review assesses microfluidic desalination techniques on their applications and is meant to contribute to further implementation of microfluidic desalination techniques in the lab-on-chip community.

  1. Visual detection technique for efficient screening and isolation of Salmonella based on a novel enrichment assay using chromatography membrane.

    PubMed

    Tang, F; Xiong, Y; Zhang, H; Wu, K; Xiang, Y; Shao, J-B; Ai, H-W; Xiang, Y-P; Zheng, X-L; Lv, J-R; Sun, H; Bao, L-S; Zhang, Z; Hu, H-B; Zhang, J-Y; Chen, L; Lu, J; Liu, W-Y; Mei, H; Ma, Y; Xu, C-F; Fang, A-Y; Gu, M; Xu, C-Y; Chen, Y; Chen, Z; Sun, Z-Y

    2016-03-01

    To detect Salmonella more efficiently and isolate strains more easily, a novel and simple detection method that uses an enrichment assay and two chromogenic reactions on a chromatography membrane was developed. Grade 3 chromatography paper is used as functionalized solid phase support (SPS), which contains specially optimized medium. One reaction for screening is based on the sulfate-reducing capacity of Salmonella. Hydrogen sulfide (H2S) generated by Salmonella reacts with ammonium ferric citrate to produce black colored ferrous sulfide. Another reaction is based on Salmonella C8 esterase that is unique for Enterobacteriaceae except Serratia and interacts with 4-methylumbelliferyl caprylate (MUCAP) to produce fluorescent umbelliferone, which is visible under ultraviolet light. A very low detection limit (10(1) CFU ml(-1)) for Salmonella was achieved on the background of 10(5) CFU ml(-1) Escherichia coli. More importantly, testing with more than 1,000 anal samples indicated that our method has a high positive detection rate and is relatively low cost, compared with the traditional culture-based method. It took only 1 day for the preliminary screening and 2 days to efficiently isolate the Salmonella cells, indicating that the new assay is specific, rapid, and simple for Salmonella detection. In contrast to the traditional culture-based method, this method can be easily used to screen and isolate targeted strains with the naked eye. The results of quantitative and comparative experiments showed that the visual detection technique is an efficient alternative method for the screening of Salmonella spp. in many applications of large-sized samples related to public health surveillance.

  2. Advanced flow MRI: emerging techniques and applications.

    PubMed

    Markl, M; Schnell, S; Wu, C; Bollache, E; Jarvis, K; Barker, A J; Robinson, J D; Rigsby, C K

    2016-08-01

    Magnetic resonance imaging (MRI) techniques provide non-invasive and non-ionising methods for the highly accurate anatomical depiction of the heart and vessels throughout the cardiac cycle. In addition, the intrinsic sensitivity of MRI to motion offers the unique ability to acquire spatially registered blood flow simultaneously with the morphological data, within a single measurement. In clinical routine, flow MRI is typically accomplished using methods that resolve two spatial dimensions in individual planes and encode the time-resolved velocity in one principal direction, typically oriented perpendicular to the two-dimensional (2D) section. This review describes recently developed advanced MRI flow techniques, which allow for more comprehensive evaluation of blood flow characteristics, such as real-time flow imaging, 2D multiple-venc phase contrast MRI, four-dimensional (4D) flow MRI, quantification of complex haemodynamic properties, and highly accelerated flow imaging. Emerging techniques and novel applications are explored. In addition, applications of these new techniques for the improved evaluation of cardiovascular (aorta, pulmonary arteries, congenital heart disease, atrial fibrillation, coronary arteries) as well as cerebrovascular disease (intra-cranial arteries and veins) are presented.

  3. Advanced flow MRI: emerging techniques and applications

    PubMed Central

    Markl, M.; Schnell, S.; Wu, C.; Bollache, E.; Jarvis, K.; Barker, A. J.; Robinson, J. D.; Rigsby, C. K.

    2016-01-01

    Magnetic resonance imaging (MRI) techniques provide non-invasive and non-ionising methods for the highly accurate anatomical depiction of the heart and vessels throughout the cardiac cycle. In addition, the intrinsic sensitivity of MRI to motion offers the unique ability to acquire spatially registered blood flow simultaneously with the morphological data, within a single measurement. In clinical routine, flow MRI is typically accomplished using methods that resolve two spatial dimensions in individual planes and encode the time-resolved velocity in one principal direction, typically oriented perpendicular to the two-dimensional (2D) section. This review describes recently developed advanced MRI flow techniques, which allow for more comprehensive evaluation of blood flow characteristics, such as real-time flow imaging, 2D multiple-venc phase contrast MRI, four-dimensional (4D) flow MRI, quantification of complex haemodynamic properties, and highly accelerated flow imaging. Emerging techniques and novel applications are explored. In addition, applications of these new techniques for the improved evaluation of cardiovascular (aorta, pulmonary arteries, congenital heart disease, atrial fibrillation, coronary arteries) as well as cerebrovascular disease (intra-cranial arteries and veins) are presented. PMID:26944696

  4. Nonuniform sampling techniques for antenna applications

    NASA Technical Reports Server (NTRS)

    Rahmat-Samii, Yahya; Cheung, Rudolf Lap-Tung

    1987-01-01

    A two-dimensional sampling technique, which can employ irregularly spaced samples (amplitude and phase) in order to generate the complete far-field patterns is presented. The technique implements a matrix inversion algorithm, which depends only on the nonuniform sampled data point locations and with no dependence on the actual field values at these points. A powerful simulation algorithm is presented to allow a real-life simulation of many reflector/feed configurations and to determine the usefulness of the nonuniform sampling technique for the copolar and cross-polar patterns. Additionally, an overlapped window concept and a generalized error simulation model are discussed to identify the stability of the technique for recovering the field data among the nonuniform sampled data. Numerical results are tailored for the pattern reconstruction of a 20-m offset reflector antenna operating at L-band. This reflector is planned to be used in a proposed measurement concept of large antenna aboard the Space Shuttle, whereby it would be almost impractical to accurately control the movement of the Shuttle with respect to the RF source in prescribed directions in order to generate uniform sampled points. Also, application of the nonuniform sampling technique to patterns obtained using near-field measured data is demonstrated. Finally, results of an actual far-field measurement are presented for the construction of patterns of a reflector antenna from a set of nonuniformly distributed measured amplitude and phase data.

  5. Nonuniform sampling techniques for antenna applications

    NASA Technical Reports Server (NTRS)

    Rahmat-Samii, Yahya; Cheung, Rudolf Lap-Tung

    1987-01-01

    A two-dimensional sampling technique, which can employ irregularly spaced samples (amplitude and phase) in order to generate the complete far-field patterns is presented. The technique implements a matrix inversion algorithm, which depends only on the nonuniform sampled data point locations and with no dependence on the actual field values at these points. A powerful simulation algorithm is presented to allow a real-life simulation of many reflector/feed configurations and to determine the usefulness of the nonuniform sampling technique for the copolar and cross-polar patterns. Additionally, an overlapped window concept and a generalized error simulation model are discussed to identify the stability of the technique for recovering the field data among the nonuniform sampled data. Numerical results are tailored for the pattern reconstruction of a 20-m offset reflector antenna operating at L-band. This reflector is planned to be used in a proposed measurement concept of large antenna aboard the Space Shuttle, whereby it would be almost impractical to accurately control the movement of the Shuttle with respect to the RF source in prescribed directions in order to generate uniform sampled points. Also, application of the nonuniform sampling technique to patterns obtained using near-field measured data is demonstrated. Finally, results of an actual far-field measurement are presented for the construction of patterns of a reflector antenna from a set of nonuniformly distributed measured amplitude and phase data.

  6. Principles, Techniques, and Applications of Tissue Microfluidics

    NASA Technical Reports Server (NTRS)

    Wade, Lawrence A.; Kartalov, Emil P.; Shibata, Darryl; Taylor, Clive

    2011-01-01

    The principle of tissue microfluidics and its resultant techniques has been applied to cell analysis. Building microfluidics to suit a particular tissue sample would allow the rapid, reliable, inexpensive, highly parallelized, selective extraction of chosen regions of tissue for purposes of further biochemical analysis. Furthermore, the applicability of the techniques ranges beyond the described pathology application. For example, they would also allow the posing and successful answering of new sets of questions in many areas of fundamental research. The proposed integration of microfluidic techniques and tissue slice samples is called "tissue microfluidics" because it molds the microfluidic architectures in accordance with each particular structure of each specific tissue sample. Thus, microfluidics can be built around the tissues, following the tissue structure, or alternatively, the microfluidics can be adapted to the specific geometry of particular tissues. By contrast, the traditional approach is that microfluidic devices are structured in accordance with engineering considerations, while the biological components in applied devices are forced to comply with these engineering presets.

  7. On-line sample preconcentration and separation technique based on transient trapping in microchip micellar electrokinetic chromatography.

    PubMed

    Sueyoshi, Kenji; Kitagawa, Fumihiko; Otsuka, Koji

    2008-02-15

    This paper describes a novel on-line sample preconcentration and separation technique named transient trapping (tr-trapping), which improves the efficiencies of separation and concentration by using a partially injected short micellar plug in microchip electrophoresis. Although a longer separation length often provides a better resolution of complexed or closely migrating analytes, our proposed theoretical model indicated that a trap-and-release mechanism enables a short micellar zone, which was partially injected into the separation channel, to work as an effective concentration and separation field. Application of the tr-trapping technique to microchip micellar electrokinetic chromatography (MCMEKC) was performed on a newly fabricated 5-way-cross microchip by using sodium dodecyl sulfate and rhodamine dyes as test micelle and analytes, respectively. When the injection times of micelle (t(inj),M) and sample solution (t(inj),S) were 1.0 and 2.0 s, respectively, both the preconcentration and separation of the dyes were completely finished within only 3.0 s. At t(inj),S of 8.0 s, a 393-fold improvement of the detectability was achieved in comparison with conventional MCMEKC. The resolution obtained with tr-trapping-MCMEKC was also better than that with conventional MCMEKC in spite of the 160-fold shorter length of the injected micellar zone at t(inj),M of 1.0 s. These results clearly demonstrated that the tr-trapping technique in MCMEKC provides a rapid, high-resolution and detectability analysis even in the short separation channel on the microchips.

  8. Neuere Chromatographie

    NASA Astrophysics Data System (ADS)

    Hostettmann, K.

    1983-04-01

    Besides high-performance liquid chromatography (HPLC) which is now a well-established and currently used technique, several emerging methods for the isolation and separation of natural products are receiving considerable attention. Centrifugal thin-layer chromatography is a very rapid technique, but limited in resolution. Of special interest are the recently developed support-free liquid-liquid chromatography methods such as droplet counter-current chromatography (DCCC) and rotation locular counter-current chromatography (RLCC). This latter method was applied to the separation of the enantiomers of (±)-norephedrine.

  9. The contribution of gas chromatography to the resynthesis of the post-Byzantine artist's technique.

    PubMed

    Kouloumpi, Eleni; Lawson, Graham; Pavlidis, Vassilios

    2007-02-01

    Gas chromatographic analysis of ethyl chloroformate derivatives of samples taken from the paint layers of post-Byzantine panel paintings permitted the successful characterisation of the different binding media used in them. This paper describes an analytical study of various post-Byzantine binding media such as egg yolk and egg/oil emulsion, using gas chromatography. The characterisation of these icons' binding media is an important task, as it contributes to our understanding of and the reconstruction of the post-Byzantine artists' palette. It also enables us to investigate the validity of our assumptions about the influences of Venetian style on Greek icon painting techniques from the sixteenth to the early nineteenth century, which up to now have been based on information in artists' handbooks. The methodology involves two experimental steps: (1) hydrolysis of the proteins and triglycerides in the binding media to obtain free amino acids and fatty acids, and (2) the formation of ethyl chloroformate derivatives via derivatization with ethyl chloroformate (ECF). This methodology is of considerable interest, since it permits the identifcation of the nature of the proteinaceous binders used in these works through the simultaneous derivatization and determination of amino acids and fatty acids. Advantages of this methodology include the small quantity of sample required and the minimum preparation time involved. The proteinaceous media can be determined based on the ratios of seven stable amino acids, while the type of emulsions and drying oils used can be determined from the fatty acid ratio.

  10. Nano-Computed Tomography: Technique and Applications.

    PubMed

    Kampschulte, M; Langheinirch, A C; Sender, J; Litzlbauer, H D; Althöhn, U; Schwab, J D; Alejandre-Lafont, E; Martels, G; Krombach, G A

    2016-02-01

    Nano-computed tomography (nano-CT) is an emerging, high-resolution cross-sectional imaging technique and represents a technical advancement of the established micro-CT technology. Based on the application of a transmission target X-ray tube, the focal spot size can be decreased down to diameters less than 400 nanometers (nm). Together with specific detectors and examination protocols, a superior spatial resolution up to 400 nm (10 % MTF) can be achieved, thereby exceeding the resolution capacity of typical micro-CT systems. The technical concept of nano-CT imaging as well as the basics of specimen preparation are demonstrated exemplarily. Characteristics of atherosclerotic plaques (intraplaque hemorrhage and calcifications) in a murine model of atherosclerosis (ApoE (-/-)/LDLR(-/-) double knockout mouse) are demonstrated in the context of superior spatial resolution in comparison to micro-CT. Furthermore, this article presents the application of nano-CT for imaging cerebral microcirculation (murine), lung structures (porcine), and trabecular microstructure (ovine) in contrast to micro-CT imaging. This review shows the potential of nano-CT as a radiological method in biomedical basic research and discusses the application of experimental, high resolution CT techniques in consideration of other high resolution cross-sectional imaging techniques. Nano-computed tomography is a high resolution CT-technology for 3D imaging at sub-micrometer resolution. The technical concept bases on a further development of the established ex-vivo-micro-CT technology. By improvement of the spatial resolution, structures at a cellular level become visible (e.g. osteocyte lacunae). © Georg Thieme Verlag KG Stuttgart · New York.

  11. Magnetic force control technique in industrial application

    NASA Astrophysics Data System (ADS)

    Nishijima, S.

    2010-11-01

    Techniques of the magnetic force control have been examined for industrial application. The problems and the technique are different in dispersion medium of gas and that of liquid. In addition, the method is different depending on the magnetic characteristic of the target objects. In case of the liquid, the dispersion medium having different viscosity was examined. The separation speed is decided with the magnitude of the magnetic force because a drag force increases with the viscosity. When the water is the dispersion medium, magnetic seeding is possible and hence the nonmagnetic materials can be separated and even the dissolved material could be separated. The separation technique has been used for purifying the waste water form paper mill or wash water of drum. On the other hand when the water is not dispersion medium, mainly the ferromagnetism particle becomes the target object because the magnetic seeding becomes difficult. The iron fragments have been separated from the slurry of slicing machine of solar battery. It has been clarified high gradient magnetic separation (HGMS) can be applied for the viscous fluid of which viscosity was as high as 10 Pa s. When the dispersion medium is gaseous material, the air is important. The drag force from air depends greatly on Reynolds number. When speed of the air is small, the Reynolds number is small, and the drag force is calculated by the Stokes' law of resistance. The study with gaseous dispersion medium is not carried out much. The magnetic separation will discuss the possibility of the industrial application of this technique.

  12. When other separation techniques fail: compound-specific carbon isotope ratio analysis of sulfonamide containing pharmaceuticals by high-temperature-liquid chromatography-isotope ratio mass spectrometry.

    PubMed

    Kujawinski, Dorothea M; Zhang, Lijun; Schmidt, Torsten C; Jochmann, Maik A

    2012-09-18

    Compound-specific isotope analysis (CISA) of nonvolatile analytes has been enabled by the introduction of the first commercial interface to hyphenate liquid chromatography with an isotope ratio mass spectrometer (LC-IRMS) in 2004, yet carbon isotope analysis of unpolar and moderately polar compounds is still a challenging task since only water as the eluent and no organic modifiers can be used to drive the separation in LC. The only way to increase the elution strength of aqueous eluents in reversed phase LC is the application of high temperatures to the mobile and stationary phases (HT-LC-IRMS). In this context we present the first method to determine carbon isotope ratios of pharmaceuticals that cannot be separated by already existing separation techniques for LC-IRMS, such as reversed phase chromatography at normal temperatures, ion-chromatography, and mixed mode chomatography. The pharmaceutical group of sulfonamides, which is generally mixed with trimethoprim in pharmaceutical products, has been chosen as probe compounds. Substance amounts as low as 0.3 μg are sufficient to perform a precise analysis. The successful applicability and reproducibility of this method is shown by the analysis of real pharmaceutical samples. The method provides the first tool to study the pharmaceutical authenticity as well as degradation and mobility of such substances in the environment by using the stable isotopic signature of these compounds.

  13. Electrochemically modulated liquid chromatography: Theoretical investigations and applications from the perspectives of chromatography and interfacial electrochemistry

    SciTech Connect

    Keller, David W.

    2005-01-01

    Electrochemically modulated liquid chromatography (EMLC) employs a conductive material as both a stationary phase for chromatographic separations and as a working electrode for performing electrochemistry experiments. This dual functionality gives EMLC the capacity to manipulate chromatographic separations by changing the potential applied (Eapp) to the stationary phase with respect to an external reference. The ability to monitor retention as a function of Eapp provides a means to chromatographically monitor electrosorption processes at solid-liquid interfaces. In this dissertation, the retention mechanism for EMLC is examined from the perspective of electrical double layer theory and interfacial thermodynamics. From the chromatographic data, it is possible to determine the interfacial excess (Λ) of a solute and changes in interfacial tension (dγ) as a function of both Eapp and the supporting electrolyte concentration. Taken together, these two experimentally manipulated parameters can be examined within the context of the Gibbs adsorption equation to delineate the contribution of a variety of interfacial properties, including the charge of solute on the stationary phase and the potential of zero charge (PZC), to the mechanism behind EMLC-based retention. The chromatographic probing of interfacial phenomena is complemented by electroanalytical experiments that exploit the ability to monitor the electronic current flowing through an EMLC column. Cyclic voltammetry and chronoamperometry of an EMLC column are used to determine the electronic performance characteristics of an EMLC column. An electrochemical flow injection analysis of a column is provided in which the current required to maintain a constant Eapp is monitored and provides a way to examine the influence that acetonitrile and supporting electrolyte composition, flow rate, column backpressure, and ionic strength have on the structure of electrified interfaces.

  14. Micro- and nanostructures and their application in gas chromatography.

    PubMed

    Mittermüller, M; Volmer, D A

    2012-07-21

    This mini-review focuses on the latest developments in the field of micro- and nanostructures in gas chromatography (GC). Significant progress has been made in recent years in designing miniaturized structures, for example, structures based on cyclodextrins. These are now commercially available and thus not the topic of this short review. Rather, we concentrate here on on-going research activities on nanoparticles, micro-electromechanical systems (MEMS) and metal-organic framework (MOF) supports as well as state-of-the-art column geometries, with particular emphasis on lab-on-a-chip columns, which undoubtedly will find their way into regular GC developments in the future.

  15. High energy heavy ions: techniques and applications

    SciTech Connect

    Alonso, J.R.

    1985-04-01

    Pioneering work at the Bevalac has given significant insight into the field of relativistic heavy ions, both in the development of techniques for acceleration and delivery of these beams as well as in many novel areas of applications. This paper will outline our experiences at the Bevalac; ion sources, low velocity acceleration, matching to the synchrotron booster, and beam delivery. Applications discussed will include the observation of new effects in central nuclear collisions, production of beams of exotic short-lived (down to 1 ..mu..sec) isotopes through peripheral nuclear collisions, atomic physics with hydrogen-like uranium ions, effects of heavy ''cosmic rays'' on satellite equipment, and an ongoing cancer radiotherapy program with heavy ions. 39 refs., 6 figs., 1 tab.

  16. Affinity monolith chromatography: A review of principles and recent analytical applications

    PubMed Central

    Pfaunmiller, Erika L.; Paulemond, Marie Laura; Dupper, Courtney M.; Hage, David S.

    2012-01-01

    Affinity monolith chromatography (AMC) is a type of liquid chromatography that uses a monolithic support and a biologically-related binding agent as a stationary phase. AMC is a powerful method for the selective separation, analysis or studies of specific target compounds in a sample. This review discusses the basic principles of AMC and recent developments or applications of this method, with particular emphasis being given to work that has appeared in the last five years. Various materials that have been used to prepare columns for AMC are examined, including organic monoliths, silica monoliths, agarose monoliths and cryogels. These supports have been used in AMC for formats that have ranged from traditional columns to disks, microcolumns and capillaries. Many binding agents have also been employed in AMC, such as antibodies, enzymes, proteins, lectins, immobilized metal-ions and dyes. Some applications that have been reported with these binding agents in AMC are bioaffinity chromatography, immunoaffinity chromatography or immunoextraction, immobilized metal-ion affinity chromatography, dye-ligand affinity chromatography, chiral separations and biointeraction studies. Examples are presented from fields that include analytical chemistry, pharmaceutical analysis, clinical testing and biotechnology. Current trends and possible future directions in AMC are also discussed. PMID:23187827

  17. Industrial application of green chromatography - II. Separation and analysis of preservatives in skincare products using subcritical water chromatography.

    PubMed

    Yang, Y; Kapalavavi, B; Gujjar, L; Hadrous, S; Marple, R; Gamsky, C

    2012-10-01

    Several high-temperature liquid chromatography (HTLC) and subcritical water chromatography (SBWC) methods have been successfully developed in this study for separation and analysis of preservatives contained in Olay skincare creams. Efficient separation and quantitative analysis of preservatives have been achieved on four commercially available ZirChrom and Waters XBridge columns at temperatures ranging from 100 to 200°C. The quantification results obtained by both HTLC and SBWC methods developed for preservatives analysis are accurate and reproducible. A large number of replicate HTLC and SBWC runs also indicate no significant system building-up or interference for skincare cream analysis. Compared with traditional HPLC separation carried out at ambient temperature, the HTLC methods can save up to 90% methanol required in the HPLC mobile phase. However, the SBWC methods developed in this project completely eliminated the use of toxic organic solvents required in the HPLC mobile phase, thus saving a significant amount of money and making the environment greener. Although both homemade and commercial systems can accomplish SBWC separations, the SBWC methods using the commercial system for preservative analysis are recommended for industrial applications because they can be directly applied in industrial plant settings. © 2012 The Authors ICS © 2012 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  18. Application of Inverse Liquid Chromatography for Surface Characterization of Biomaterials.

    PubMed

    Adamska, Katarzyna; Kadlec, Karol; Voelkel, Adam

    In the present study, a novel approach for surface characterization of ceramic biomaterials is proposed. Two ceramic biomaterials-hydroxyapatite and β-tricalcium phosphate-were examined by means of inverse liquid chromatography. The Abraham LFER model was applied for physicochemical characteristics of the surface. Different compounds, characterized by different polarity and different donor-acceptor properties of functional group, were used as test solutes. The chromatographic experiments were carried out with two compositions of the mobile phase: pure acetonitrile (MeCN) and the mixture of acetonitrile and water in 80:20 ratio (MeCN/H2O). Thus, the influence of mobile phase on sorption properties of hydroxyapatite and tricalcium phosphate surface was also discussed.

  19. [Application of chromatography methods for the diagnostics of systemic inflammation].

    PubMed

    Pastukhova, N K; Starkov, G E

    2010-01-01

    Specific manifestations of systemic inflammation in patients with acute destructive cholecystitis in the postoperative period were studied by the methods of high-precision exclusive liquid chromatography with chromatograph "Trirotar" (Japan) with columns "Polysep G-5", "Toyopearl-Sw - 2000-2500". It was found that systemic inflammation was accompanied by active accumulation of middle- and low-molecular mass. Later their spectrum was found to change when going over to unfavorable clinical course. In patients with septic shock there occurred enrichment of the chromatographic picture spectrum with new peaks (substances which can be considered as endotoxins), decrease of the albumin concentration, as well as increase of dispersity of the biochemical composition of blood.

  20. Principles, Techniques, and Applications of Tissue Microfluidics

    NASA Technical Reports Server (NTRS)

    Wade, Lawrence A.; Kartalov, Emil P.; Shibata, Darryl; Taylor, Clive

    2011-01-01

    The principle of tissue microfluidics and its resultant techniques has been applied to cell analysis. Building microfluidics to suit a particular tissue sample would allow the rapid, reliable, inexpensive, highly parallelized, selective extraction of chosen regions of tissue for purposes of further biochemical analysis. Furthermore, the applicability of the techniques ranges beyond the described pathology application. For example, they would also allow the posing and successful answering of new sets of questions in many areas of fundamental research. The proposed integration of microfluidic techniques and tissue slice samples is called tissue microfluidics because it molds the microfluidic architectures in accordance with each particular structure of each specific tissue sample. Thus, microfluidics can be built around the tissues, following the tissue structure, or alternatively, the microfluidics can be adapted to the specific geometry of particular tissues. By contrast, the traditional approach is that microfluidic devices are structured in accordance with engineering considerations, while the biological components in applied devices are forced to comply with these engineering presets. The proposed principles represent a paradigm shift in microfluidic technology in three important ways: Microfluidic devices are to be directly integrated with, onto, or around tissue samples, in contrast to the conventional method of off-chip sample extraction followed by sample insertion in microfluidic devices. Architectural and operational principles of microfluidic devices are to be subordinated to suit specific tissue structure and needs, in contrast to the conventional method of building devices according to fluidic function alone and without regard to tissue structure. Sample acquisition from tissue is to be performed on-chip and is to be integrated with the diagnostic measurement within the same device, in contrast to the conventional method of off-chip sample prep and

  1. The Binding of Biotin to Sepharose-Avidin Column: Demonstration of the Affinity Chromatography Technique

    ERIC Educational Resources Information Center

    Landman, A. D.; Landman, N. N.

    1976-01-01

    Describes a biochemistry experiment that illustrates the methodology of affinity chromatography by attaching avidin, a glycoprotein in egg white, to a Sepharose matrix in order to bind biotin-containing proteins. (MLH)

  2. The Binding of Biotin to Sepharose-Avidin Column: Demonstration of the Affinity Chromatography Technique

    ERIC Educational Resources Information Center

    Landman, A. D.; Landman, N. N.

    1976-01-01

    Describes a biochemistry experiment that illustrates the methodology of affinity chromatography by attaching avidin, a glycoprotein in egg white, to a Sepharose matrix in order to bind biotin-containing proteins. (MLH)

  3. Analysis of chemical signals in red fire ants by gas chromatography and pattern recognition techniques

    USDA-ARS?s Scientific Manuscript database

    The combination of gas chromatography and pattern recognition (GC/PR) analysis is a powerful tool for investigating complicated biological problems. Clustering, mapping, discriminant development, etc. are necessary to analyze realistically large chromatographic data sets and to seek meaningful relat...

  4. Clinical Application of the Forced Oscillation Technique.

    PubMed

    Shirai, Toshihiro; Kurosawa, Hajime

    2016-01-01

    The forced oscillation technique (FOT) is a noninvasive method with which to measure respiratory system resistance and reactance during tidal breathing. Recently, its clinical application has spread worldwide with the expansion of commercially available broadband frequency FOT devices, including MostGraph and Impulse Oscillometry. An increasing number of reports have supported the usefulness of the FOT in the management of asthma and chronic obstructive pulmonary disease (COPD). However, the FOT is not a surrogate test for spirometry, but should be used complementarily. Furthermore, reference values are not necessarily available and the interpretation of some measured data is controversial. There is a need to update the international statement for not only technical aspects but also the clinical use of the FOT. In this review, we summarize the previously published studies and discuss how to use the FOT in a clinical setting.

  5. Flight Acoustics Measurement Techniques and Applications

    NASA Technical Reports Server (NTRS)

    Preisser, J. S.; Marcolini, M. A.

    1998-01-01

    Careful consideration must be given to data acquisition and analysis techniques in the design of experiments for the measurement of noise generated by flight vehicles. Although noise measurement locations and data reduction procedures are specified for aircraft certification by FAA and ICAO directives, for example, there are virtually no established procedures for aircraft noise measurement for other purposes. To optimize the quality and quantity of information obtained in a flight acoustics experiment, microphone layout, data acquisition, and analysis must be tailored to the specific test objective. This paper will review flight acoustics technology at NASA Langley Research Center developed over the past decade. In particular, the paper will focus on flight experiments performed for three diverse objectives: (1) research applications, such as noise prediction code validation, (2) noise impact modeling, and (3) noise abatement flight procedures. To best achieve these diverse objectives, different deployments of microphone systems on the ground are required, and different data analysis techniques are needed. In all cases, accurate positioning of the aircraft synchronized in time with the data recording is necessary. However, there are some restrictions on flight operations unique to each case for the methods to properly work.

  6. A Gas Chromatography Experiment for Proving the Application of Quantum Symmetry Restrictions in Homonuclear Diatomic Molecules.

    ERIC Educational Resources Information Center

    Dosiere, M.

    1985-01-01

    Background information, procedures used, and typical results obtained are provided for an experiment in which gas chromatography is used to prove the application of quantum symmetry restrictions in homonuclear diatomic molecules. Comparisons between experimental results and theoretical computed values show good agreement, within one to two…

  7. Review of recent developments and applications in low-pressure (vacuum outlet) gas chromatography

    USDA-ARS?s Scientific Manuscript database

    The concept of low pressure (LP) vacuum outlet gas chromatography (GC) was introduced more than 50 years ago, but it was not until the 2000s that its theoretical applicability to fast analysis of GC-amenable chemicals was realized. In practice, LPGC is implemented by placing the outlet of a short, ...

  8. A Gas Chromatography Experiment for Proving the Application of Quantum Symmetry Restrictions in Homonuclear Diatomic Molecules.

    ERIC Educational Resources Information Center

    Dosiere, M.

    1985-01-01

    Background information, procedures used, and typical results obtained are provided for an experiment in which gas chromatography is used to prove the application of quantum symmetry restrictions in homonuclear diatomic molecules. Comparisons between experimental results and theoretical computed values show good agreement, within one to two…

  9. Recent applications of nuclear track emulsion technique

    SciTech Connect

    Zarubin, P. I.

    2016-12-15

    A survey of recent results obtained using the nuclear track emulsion (NTE) technique in low energy applications is given. NTE irradiation with 60 MeV {sup 8}He nuclei provides identification of their decays at stopping, evaluation of the possibility of α range spectrometry, and observation of drift of thermalized {sup 8}He atoms. Correlations of α particles studied in {sup 12}C → 3α splitting induced by 14.1 MeV neutrons indicate the presence of a superposition of 0{sup +} and 2{sup +} states of the {sup 8}Be nucleus in the ground state of {sup 12}C. Angular correlations of fragments are studied in boron-enriched NTE, and the prospects of NTE application in radioactivity and nuclear fission research are discussed. It is proposed to use an automated microscope to search for collinear tripartition of heavy nuclei implanted in NTE. Surface irradiation of NTE by a {sup 252}Cf source is started. Planar events containing fragment pairs and long range α particles, as well as fragment triples, are studied. NTE samples are calibrated using Kr and Xe ions with an energy of 1.2 and 3 A MeV.

  10. [Determination of acetanilide herbicide residues in tea by gas chromatography-mass spectrometry with two different ionization techniques].

    PubMed

    Shen, Weijian; Xu, Jinzhong; Yang, Wenquan; Shen, Chongyu; Zhao, Zengyun; Ding, Tao; Wu, Bin

    2007-09-01

    An analytical method of solid phase extraction-gas chromatography-mass spectrometry with two different ionization techniques was established for simultaneous determination of 12 acetanilide herbicide residues in tea-leaves. Herbicides were extracted from tea-leaf samples with ethyl acetate. The extract was cleaned-up on an active carbon SPE column connected to a Florisil SPE column. Analytical screening was determined by the technique of gas chromatography (GC)-mass spectrometry (MS) in the selected ion monitoring (SIM) mode with either electron impact ionization (EI) or negative chemical ionization (NCI). It is reliable and stable that the recoveries of all herbicides were in the range from 50% to 110% at three spiked levels, 10 microg/kg, 20 microg/kg and 40 microg/kg, and the relative standard deviations (RSDs) were no more than 10.9%. The two different ionization techniques are complementary as more ion fragmentation information can be obtained from the EI mode while more molecular ion information from the NCI mode. By comparison of the two techniques, the selectivity of NCI-SIM was much better than that of EI-SIM method. The sensitivities of the both techniques were high, the limit of quantitative (LOQ) for each herbicide was no more than 2.0 microg/kg, and the limit of detection (LOD) with NCI-SIM technique was much lower than that of EI-SIM when analyzing herbicides with several halogen atoms in the molecule.

  11. Establishment and application of milk fingerprint by gel filtration chromatography.

    PubMed

    Gao, P; Li, J; Li, Z; Hao, J; Zan, L

    2016-12-01

    Raw milk adulteration frequently occurs in undeveloped countries. It not only reduces the nutritional value of milk, but it is also harmful to consumers. In this paper, we focused on investigating an efficient method for the quality control of raw milk protein. A gel filtration chromatography (GFC) fingerprint method combined with chemometrics was developed for fingerprint analysis of raw milk. To optimize the GFC conditions, milk fat was removed by centrifugation, and GFC analysis was performed on a Superdex 75 10/300GL column (Just Scientific, Shanghai, China) with 0.2 M NaH2PO4-Na2HPO4 buffer (pH 7.0) as the mobile phase. The flow rate was 0.5mL/min, and the detection wavelength was set at 280 nm. Ten batches of 120 raw milk samples were analyzed to establish the GFC fingerprint under optimal conditions. Six major peaks common to the chromatogram of each raw milk sample were selected for fingerprint analysis, and the characteristic peaks were used to establish a standard chromatographic fingerprint. Principal component analysis was then applied to classify GFC information of adulterated milk and raw milk, allowing adulterated samples to be effectively screened out from the raw milk in principal component analysis scores plot. The fingerprint method demonstrates promising features in detecting milk protein adulteration.

  12. Microwave high performance liquid chromatography with UV-visible detection. Application to vitamins determination.

    PubMed

    Terol, Amanda; Maestre, Salvador E; Prats, Soledad; Todolí, José L

    2012-05-07

    The present work describes the first attempt to use microwave reversed phase high performance liquid chromatography (MW-HPLC) to carry out the separation of organic compounds. Biotin and riboflavin were selected for the characterization of the new separation technique. Additional vitamins (nicotinamide, pyridoxine and thiamine) were used as reference compounds. In order to perform the separation, a chromatographic column was placed inside a domestic microwave oven in a hanging position. The column particular location was an extremely critical point, since it precluded the actual power absorbed by the sample. In order to avoid magnetron damage, a heat well (i.e., water vessels) was used. Vitamins were detected using a UV-VIS detector. Results obtained showed that the application of microwave radiation, even at low power levels, gave rise to a significant modification in the characteristics of the chromatograms. It was found that retention times for biotin and riboflavin shortened as the power increased. Furthermore, the peak shape also changed, with the modification being more significant for the former vitamin than for the latter one. Furthermore, sensitivity also increased as the column was exposed to the action of microwave. Comparatively speaking, MW-HPLC was more efficient in terms of compound separation than when performed at room temperature or thermostatted at 45 °C HPLC. This was likely due to the combined action of a moderate and quick heating of the mobile phase with an increase in the analytes diffusivity caused by the radiation.

  13. Simple coupled ultrahigh performance liquid chromatography and ion chromatography technique for simultaneous determination of folic acid and inorganic anions in folic acid tablets.

    PubMed

    Wang, Fenglian; Cao, Minyi; Wang, Nani; Muhammad, Nadeem; Wu, Shuchao; Zhu, Yan

    2018-01-15

    Folic acid plays a significant role during periods of rapid cells division and growth. Pregnant women require folic acid daily, either from dietary supplements or folic acid tablets in order to prevent fetal neural tube defects. In this work, a simple coupled ultrahigh performance liquid chromatography and ion chromatography technique was developed for simultaneous determination of folic acid and inorganic anions in folic acid tablets. A reversed-phase C18 column was used as the pretreatment column for on-line separating inorganic anions from organics. Inorganic anions were concentrated in the concentration column. Under the optimal chromatographic conditions, good sensitivity and linear calibration-curves (r≥0.9992) were obtained. Low detection limits were obtained in the range of 0.0032-0.40mgL(-1) for all analytes. Repeatability results were satisfactory with relative standard deviations less than 1.50% (n=5). The developed method was utilized to analyze spiked folic acid tablet samples with good measured recoveries (92.4-107.4%). Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Centrifugal precipitation chromatography, a powerful technique for the isolation of active enzymes from tea leaves (Camellia sinensis).

    PubMed

    Baldermann, Susanne; Fleischmann, Peter; Bolten, Mareike; Watanabe, Naoharu; Winterhalter, Peter; Ito, Yoichiro

    2009-05-08

    Centrifugal precipitation chromatography was developed approximately 10 years ago. In contrast to other counter-current chromatographic techniques, the centrifugal precipitation chromatography system is operated with two mutually miscible solutions separated by a cut-off membrane. Centrifugal precipitation chromatography was firstly introduced for the separation of proteins using an ammonium sulfate gradient. In this study we describe a novel approach using solvent-based protein precipitation for the isolation of active plant enzymes from tea leaves (Camellia sinensis) by centrifugal precipitation chromatography. We developed a gradient based on acetone and Tris-buffer, because the biological activity of carotenases in tea leaves cannot be preserved in the presence of ammonium sulfate. Parameters such as the critical solvent concentration, flow rate, buffer concentration, and sample load were determined and/or optimized. Subsequently, the newly developed separation protocol was successfully used for the isolation of active carotenoid cleavage enzymes from tea leaves. The isolated enzymes showed high enzymatic activities and purities and could be directly used for enzymatic assays and structure elucidation.

  15. Recent Advances in Techniques for Starch Esters and the Applications: A Review

    PubMed Central

    Hong, Jing; Zeng, Xin-An; Brennan, Charles S.; Brennan, Margaret; Han, Zhong

    2016-01-01

    Esterification is one of the most important methods to alter the structure of starch granules and improve its applications. Conventionally, starch esters are prepared by conventional or dual modification techniques, which have the disadvantages of being expensive, have regent overdoses, and are time-consuming. In addition, the degree of substitution (DS) is often considered as the primary factor in view of its contribution to estimate substituted groups of starch esters. In order to improve the detection accuracy and production efficiency, different detection techniques, including titration, nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis/infrared spectroscopy (TGA/IR) and headspace gas chromatography (HS-GC), have been developed for DS. This paper gives a comprehensive overview on the recent advances in DS analysis and starch esterification techniques. Additionally, the advantages, limitations, some perspectives on future trends of these techniques and the applications of their derivatives in the food industry are also presented. PMID:28231145

  16. Recent Advances in Techniques for Starch Esters and the Applications: A Review.

    PubMed

    Hong, Jing; Zeng, Xin-An; Brennan, Charles S; Brennan, Margaret; Han, Zhong

    2016-07-09

    Esterification is one of the most important methods to alter the structure of starch granules and improve its applications. Conventionally, starch esters are prepared by conventional or dual modification techniques, which have the disadvantages of being expensive, have regent overdoses, and are time-consuming. In addition, the degree of substitution (DS) is often considered as the primary factor in view of its contribution to estimate substituted groups of starch esters. In order to improve the detection accuracy and production efficiency, different detection techniques, including titration, nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis/infrared spectroscopy (TGA/IR) and headspace gas chromatography (HS-GC), have been developed for DS. This paper gives a comprehensive overview on the recent advances in DS analysis and starch esterification techniques. Additionally, the advantages, limitations, some perspectives on future trends of these techniques and the applications of their derivatives in the food industry are also presented.

  17. Ion-exchange chromatography: basic principles and application to the partial purification of soluble mammalian prolyl oligopeptidase.

    PubMed

    Cummins, Philip M; Dowling, Oonagh; O'Connor, Brendan F

    2011-01-01

    Ion-exchange chromatography (IEC) allows for the separation of ionizable molecules on the basis of differences in charge properties. Its large sample-handling capacity, broad applicability (particularly to proteins and enzymes), moderate cost, powerful resolving ability, and ease of scale-up and automation have led to it becoming one of the most versatile and widely used of all liquid chromatography (LC) techniques. In this chapter, we review the basic principles of IEC, as well as the broader criteria for selecting IEC conditions. By way of further illustration, we outline protocols necessary to partially purify a serine peptidase from bovine whole brain cytosolic fraction, covering crude tissue extract preparation through to partial purification of the target enzyme using anion-exchange chromatography. Protocols for assaying total protein and enzyme activity in both pre- and post-IEC fractions are also described. The target serine peptidase, prolyl oligopeptidase (POP, EC3.4.21.26), is an 80-kDa enzyme with endopeptidase activity towards peptide substrates of ≤30 amino acids. POP is a ubiquitous post-proline cleaving enzyme with particularly high expression levels in the mammalian brain, where it participates in the metabolism of neuroactive peptides and peptide-like hormones (e.g. thyroliberin, gonadotropin-releasing hormone).

  18. Application of ion chromatography to the study of hydrolysis of some halogenated hydrocarbons at ambient temperatures

    NASA Technical Reports Server (NTRS)

    Otterson, D. A.

    1978-01-01

    The application of ion chromatography to the study of very slow rates of hydrolysis of some halogenated hydrocarbons was investigated. The halide concentrations in the aqueous phase of mixtures of a carbonate buffer (pH = 10.3) and either chloroform (CHC13) or fluorotrichloromethane (CFC13) after aging for various lengths of time at room temperature, were determined by ion chromatography. Hydrolysis of CHC13 caused the C1(-) concentration to increase by about 1500 ppb per day. On the other hand neither the F(-) or C1(-) concentration in the CFC13 mixture increased by as much as 1 ppb per day. The magnitude of errors in the determination of halides prevented any firm conclusions regarding hydrolysis in this mixture. However, these results were used to show how ion chromatography could expedite identification of the hydrolyzing substance as well as investigations of hydrolysis mechanisms.

  19. Application of Geophysical Techniques in Glaciology

    NASA Astrophysics Data System (ADS)

    Murray, T.

    2006-05-01

    Glaciologists are faced with the problem that most processes that control ice motion or the transport of water and sediment occur either deep within the glacier ice or at the interface between it and the underlying substrate. However, glaciers are an ideal environment for the application of many geophysical techniques and they have led to significant advances in our understanding of glaciers and ice sheets. Surface and airborne radar has a long pedigree in glaciology and has been used extensively to map beds of the major ice sheets and isochrones within the ice. Cold ice, such as that in Antarctica is easy for radar energy to penetrate, but the water in warm ice scatters radar energy. For this reason it has proved more difficult to image the beds of outlet glaciers in Greenland. Recent advances, particularly in ground-penetrating radar, have meant that it has been possible to image sediment structures within the ice and to use the reflectivity at the bed capture some aspects of the basal water system. Radar energy does not normally penetrate into the beds of ice masses - which are often wet sediments. However, reflection seismics allows us to image further into the basal environment. Using the impedance contrast across the basal interface it is possible to determine whether basal sediments are frozen or unfrozen, and whether they are actively deforming or the ice is sliding over the bed. These questions are key in understanding the dynamics of an ice mass. As a glacier moves overs its bed, seismic energy can be released that provides information on the nature of the basal environment. These events record different source types and relative friction between regions of the bed (so-called "sticky" and "slippery" spots). Considerable work is required to fully exploit the potential of this technique which requires integration with GPS measurements, locating events, and modeling of source types. Geophysical techniques are an ideal tool for exploring the inaccessible

  20. Application of Geophysical Techniques in Glaciology

    NASA Astrophysics Data System (ADS)

    Murray, T.

    2006-05-01

    Glaciologists are faced with the problem that most processes that control ice motion or the transport of water and sediment occur either deep within the glacier ice or at the interface between it and the underlying substrate. However, glaciers are an ideal environment for the application of many geophysical techniques and they have led to significant advances in our understanding of glaciers and ice sheets. Surface and airborne radar has a long pedigree in glaciology and has been used extensively to map beds of the major ice sheets and isochrones within the ice. Cold ice, such as that in Antarctica is easy for radar energy to penetrate, but the water in warm ice scatters radar energy. For this reason it has proved more difficult to image the beds of outlet glaciers in Greenland. Recent advances, particularly in ground-penetrating radar, have meant that it has been possible to image sediment structures within the ice and to use the reflectivity at the bed capture some aspects of the basal water system. Radar energy does not normally penetrate into the beds of ice masses - which are often wet sediments. However, reflection seismics allows us to image further into the basal environment. Using the impedance contrast across the basal interface it is possible to determine whether basal sediments are frozen or unfrozen, and whether they are actively deforming or the ice is sliding over the bed. These questions are key in understanding the dynamics of an ice mass. As a glacier moves overs its bed, seismic energy can be released that provides information on the nature of the basal environment. These events record different source types and relative friction between regions of the bed (so-called "sticky" and "slippery" spots). Considerable work is required to fully exploit the potential of this technique which requires integration with GPS measurements, locating events, and modeling of source types. Geophysical techniques are an ideal tool for exploring the inaccessible

  1. [Application of three-dimensional printing technique in orthopaedics].

    PubMed

    Luo, Qiang; Lau, Tak Wing; Fang, Xinshuo; Leung, Frankie

    2014-03-01

    To review the current progress of three-dimensional (3-D) printing technique in the clinical practice, its limitations and prospects. The recent publications associated with the clinical application of 3-D printing technique in the field of surgery, especially in orthopaedics were extensively reviewed. Currently, 3-D printing technique has been applied in orthopaedic surgery to aid diagnosis, make operative plans, and produce personalized prosthesis or implants. 3-D printing technique is a promising technique in clinical application.

  2. [Progress in transgenic fish techniques and application].

    PubMed

    Ye, Xing; Tian, Yuan-Yuan; Gao, Feng-Ying

    2011-05-01

    Transgenic technique provides a new way for fish breeding. Stable lines of growth hormone gene transfer carps, salmon and tilapia, as well as fluorescence protein gene transfer zebra fish and white cloud mountain minnow have been produced. The fast growth characteristic of GH gene transgenic fish will be of great importance to promote aquaculture production and economic efficiency. This paper summarized the progress in transgenic fish research and ecological assessments. Microinjection is still the most common used method, but often resulted in multi-site and multi-copies integration. Co-injection of transposon or meganuclease will greatly improve the efficiency of gene transfer and integration. "All fish" gene or "auto gene" should be considered to produce transgenic fish in order to eliminate misgiving on food safety and to benefit expression of the transferred gene. Environmental risk is the biggest obstacle for transgenic fish to be commercially applied. Data indicates that transgenic fish have inferior fitness compared with the traditional domestic fish. However, be-cause of the genotype-by-environment effects, it is difficult to extrapolate simple phenotypes to the complex ecological interactions that occur in nature based on the ecological consequences of the transgenic fish determined in the laboratory. It is critical to establish highly naturalized environments for acquiring reliable data that can be used to evaluate the environ-mental risk. Efficacious physical and biological containment strategies remain to be crucial approaches to ensure the safe application of transgenic fish technology.

  3. Digitally Enhanced Thin-Layer Chromatography: An Inexpensive, New Technique for Qualitative and Quantitative Analysis

    ERIC Educational Resources Information Center

    Hess, Amber Victoria Irish

    2007-01-01

    A study conducted shows that if digital photography is combined with regular thin-layer chromatography (TLC), it could perform highly improved qualitative analysis as well as make accurate quantitative analysis possible for a much lower cost than commercial equipment. The findings suggest that digitally enhanced TLC (DE-TLC) is low-cost and easy…

  4. Digitally Enhanced Thin-Layer Chromatography: An Inexpensive, New Technique for Qualitative and Quantitative Analysis

    ERIC Educational Resources Information Center

    Hess, Amber Victoria Irish

    2007-01-01

    A study conducted shows that if digital photography is combined with regular thin-layer chromatography (TLC), it could perform highly improved qualitative analysis as well as make accurate quantitative analysis possible for a much lower cost than commercial equipment. The findings suggest that digitally enhanced TLC (DE-TLC) is low-cost and easy…

  5. Optimization of the separation of lysergic acid diethylamide in urine by a sweeping technique using micellar electrokinetic chromatography.

    PubMed

    Fang, Ching; Liu, Ju-Tsung; Lin, Cheng-Huang

    2002-07-25

    The separation and on-line concentrations of lysergic acid diethylamide (LSD), iso-lysergic acid diethylamide (iso-LSD) and lysergic acid N,N-methylpropylamide (LAMPA) in human urine were investigated by capillary electrophoresis-fluorescence spectroscopy using sodium dodecyl sulfate (SDS) as an anionic surfactant. A number of parameters such as buffer pH, SDS concentration, Brij-30 concentration and the content of organic solvent used in separation, were optimized. The techniques of sweeping-micellar electrokinetic chromatography (sweeping-MEKC) and cation-selective exhaustive injection-sweep-micellar electrokinetic chromatography (CSEI-sweep-MEKC) were used for determining on-line concentrations. The advantages and disadvantages of this procedure with respect to sensitivity, precision and simplicity are discussed and compared. Copyright 2002 Elsevier Science BV.

  6. Applications of liquid chromatography-mass spectrometry for food analysis.

    PubMed

    Di Stefano, Vita; Avellone, Giuseppe; Bongiorno, David; Cunsolo, Vincenzo; Muccilli, Vera; Sforza, Stefano; Dossena, Arnaldo; Drahos, László; Vékey, Károly

    2012-10-12

    HPLC-MS applications in the agrifood sector are among the fastest developing fields in science and industry. The present tutorial mini-review briefly describes this analytical methodology: HPLC, UHPLC, nano-HPLC on one hand, mass spectrometry (MS) and tandem mass spectrometry (MS/MS) on the other hand. Analytical results are grouped together based on the type of chemicals analyzed (lipids, carbohydrates, glycoproteins, vitamins, flavonoids, mycotoxins, pesticides, allergens and food additives). Results are also shown for various types of food (ham, cheese, milk, cereals, olive oil and wines). Although it is not an exhaustive list, it illustrates the main current directions of applications. Finally, one of the most important features, the characterization of food quality (including problems of authentication and adulteration) is discussed, together with a future outlook on future directions. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Principles and Applications of Liquid Chromatography-Mass Spectrometry in Clinical Biochemistry

    PubMed Central

    Pitt, James J

    2009-01-01

    Liquid chromatography-mass spectrometry (LC-MS) is now a routine technique with the development of electrospray ionisation (ESI) providing a simple and robust interface. It can be applied to a wide range of biological molecules and the use of tandem MS and stable isotope internal standards allows highly sensitive and accurate assays to be developed although some method optimisation is required to minimise ion suppression effects. Fast scanning speeds allow a high degree of multiplexing and many compounds can be measured in a single analytical run. With the development of more affordable and reliable instruments, LC-MS is starting to play an important role in several areas of clinical biochemistry and compete with conventional liquid chromatography and other techniques such as immunoassay. PMID:19224008

  8. Homochiral metal-organic frameworks and their application in chromatography enantioseparations.

    PubMed

    Peluso, Paola; Mamane, Victor; Cossu, Sergio

    2014-10-10

    The last frontier in the chiral stationary phases (CSPs) field for chromatography enantioseparations is represented by homochiral metal-organic frameworks (MOFs), a class of organic-inorganic hybrid materials built from metal-connecting nodes and organic-bridging ligands. The modular nature of these materials allows to design focused structures by combining properly metal, organic ligands and rigid polytopic spacers. Intriguingly, chiral ligands introduce molecular chirality in the MOF-network as well as homochirality in the secondary structure of materials (such as homohelicity) producing homochiral nets in a manner mimicking biopolymers (proteins, polysaccharides) which are characterized by a definite helical sense associated with the chirality of their building blocks (amino acids or sugars). Nowadays, robust and flexible materials characterized by high porosity and surface area became available by using preparative procedures typical of the so-called reticular synthesis. This review focuses on recent developments in the synthesis and applications of homochiral MOFs as supports for chromatography enantioseparations. Indeed, despite this field is in its infancy, interesting results have been produced and a critical overview of the 12 reported applications for gas chromatography (GC) and high-performance liquid chromatography (HPLC) can orient the reader approaching the field. Mechanistic aspects are shortly discussed and a view regarding future trends in this field is provided. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Application of different modes of thin-layer chromatography and mass spectrometry for the separation and detection of large and small biomolecules.

    PubMed

    Tuzimski, Tomasz

    2011-12-09

    Biomolecules are widespread throughout the world. A biomolecule is any organic molecule produced by a living organism, including large polymeric molecules such as proteins, polysaccharides and nucleic acids. Many sample preparation techniques are used in biomolecule analysis; the method selected depends on the complexity of the sample, the nature of the matrix and the analytes, and the analytical technique available. This review covers the current state of knowledge on thin-layer chromatography and mass spectrometry for qualitative analysis of biomolecules. In the first part of the paper the reader will gain useful information to avoid some problems about performing various modes of thin-layer chromatography combined with mass spectrometry experiments and in the second part he will find useful information for application of these techniques for separation, detection, and qualitative investigation of structures and quantitative determination of biomolecules such as proteins, peptides, oligonucleotides, amino acids, DNA, RNA, and lipids.

  10. Application in pesticide analysis: Liquid chromatography - A review of the state of science for biomarker discovery and identification

    EPA Science Inventory

    Book Chapter 18, titled Application in pesticide analysis: Liquid chromatography - A review of the state of science for biomarker discovery and identification, will be published in the book titled High Performance Liquid Chromatography in Pesticide Residue Analysis (Part of the C...

  11. Application in pesticide analysis: Liquid chromatography - A review of the state of science for biomarker discovery and identification

    EPA Science Inventory

    Book Chapter 18, titled Application in pesticide analysis: Liquid chromatography - A review of the state of science for biomarker discovery and identification, will be published in the book titled High Performance Liquid Chromatography in Pesticide Residue Analysis (Part of the C...

  12. Measuring fuel contamination using high speed gas chromatography and cone penetration techniques

    SciTech Connect

    Farrington, S.P.; Bratton, W.L.; Akard, M.L.

    1995-10-01

    Decision processes during characterization and cleanup of hazardous waste sites are greatly retarded by the turnaround time and expense incurred through the use of conventional sampling and laboratory analyses. Furthermore, conventional soil and groundwater sampling procedures present many opportunities for loss of volatile organic compounds (VOC) by exposing sample media to the atmosphere during transfers between and among sampling devices and containers. While on-site analysis by conventional gas chromatography can reduce analytical turnaround time, time-consuming sample preparation procedures are still often required, and the potential for loss of VOC is not reduced. This report describes the development of a high speed gas chromatography and cone penetration testing system which can detect and measure subsurface fuel contamination in situ during the cone penetration process.

  13. Selective comprehensive multidimensional separation for resolution enhancement in high performance liquid chromatography. Part II: applications.

    PubMed

    Groskreutz, Stephen R; Swenson, Michael M; Secor, Laura B; Stoll, Dwight R

    2012-03-09

    In this second paper of a two-part series, we demonstrate the utility of an approach to enhancing the resolution of select portions of conventional 1D-LC separations, which we refer to as selective comprehensive two-dimensional HPLC (sLC × LC), in three quite different example applications. In the first paper of the series we described the principles of this approach, which breaks the long-standing link in online multi-dimensional chromatography between the timescales of sampling the first dimension (¹D) separation and the separation of fractions of ¹D effluent in the second dimension. In the first example, the power of the sLC × LC approach to significantly reduce the analysis time and method development effort is demonstrated by selectively enhancing the resolution of critical pairs of peaks that are unresolved by a one-dimensional separation (1D-LC) alone. Transfer and subsequent ²D separations of multiple fractions of a particular ¹D peak produces a two-dimensional chromatogram that reveals the coordinates of the peaks in the 2D separation space. The added time dimension of sLC × LC chromatograms also facilitates the application of sophisticated chemometric curve resolution algorithms to further resolve peaks that are otherwise chromatographically unresolved. This is demonstrated in this work by the targeted analysis of phenytoin in urban wastewater effluent using UV diode array detection. Quantitation by both standard addition and external calibration methods yielded results that were not statistically different from 2D-LC/MS/MS analysis of the same samples. Next, we demonstrate the utility of sLC × LC for reducing ion suppression due to matrix effects in electrospray ionization mass spectrometry through the analysis of cocaine in urban wastewater effluent. Finally, we explore the flexibility of the approach in its application to two select regions of a single ¹D separation of triclosan and cocaine. The diversity of these applications demonstrates the

  14. Automated sample preparation techniques for the determination of drug enantiomers in biological fluids using liquid chromatography with chiral stationary phases.

    PubMed

    Ceccato, A; Toussaint, B; Chiap, P; Hubert, P; Crommen, J

    1999-01-01

    The determination of drug enantiomers has become of prime importance in the field of pharmaceutical and biomedical analysis. Liquid chromatography (LC) is one of the most frequently used techniques for achieving the separation and quantitation of the enantiomers of drug compounds. In the bioanalytical field, the integrated systems present an interesting alternative to time-consuming sample preparation techniques such as liquid-liquid extraction. Solid phase extraction (SPE) on disposable cartridges, dialysis or column switching are sample preparation techniques that can be fully automated and applied to enantioselective analysis in biological fluids. The selection of the most appropriate LC mode and chiral stationary phase for enantioseparations in bioanalysis is discussed and some aspects of these automated sample preparation procedures are compared, such as selectivity, detectability, elution of the analytes from the extraction sorbent, sample volume and analyte stability.

  15. Application of metabonomic analytical techniques in the modernization and toxicology research of traditional Chinese medicine

    PubMed Central

    Lao, Yong-Min; Jiang, Jian-Guo; Yan, Lu

    2009-01-01

    In the recent years, a wide range of metabonomic analytical techniques are widely used in the modern research of traditional Chinese medicine (TCM). At the same time, the international community has attached increasing importance to TCM toxicity problems. Thus, many studies have been implemented to investigate the toxicity mechanisms of TCM. Among these studies, many metabonomic-based methods have been implemented to facilitate TCM toxicity investigation. At present, the most prevailing methods for TCM toxicity research are mainly single analysis techniques using only one analytical means. These techniques include nuclear magnetic resonance (NMR), gas chromatography-mass spectrometry (GC-MS), and liquid chromatography-mass spectrometry (LC-MS), etc.; with these techniques, some favourable outcomes have been gained in the toxic reaction studies of TCM, such as the action target organs assay, the establishment of action pattern, the elucidation of action mechanism and the exploration of action material foundation. However, every analytical technique has its advantages and drawbacks, no existing analytical technique can be versatile. Multi-analysed techniques can partially overcome the shortcomings of single-analysed techniques. Combination of GC-MS and LC-MS metabolic profiling approaches has unravelled the pathological outcomes of aristolochic acid-induced nephrotoxicity, which can not be achieved by single-analysed techniques. It is believed that with the further development of metabonomic analytical techniques, especially multi-analysed techniques, metabonomics will greatly promote TCM toxicity research and be beneficial to the modernization of TCM in terms of extending the application of modern means in the TCM safety assessment, assisting the formulation of TCM safety norms and establishing the international standards indicators. PMID:19508399

  16. [Application of virtual reality technique in forensic pathology].

    PubMed

    Xiao, Jian; Zhang, Hui-xia; Liu, Liang

    2005-05-01

    This article reviewed general information, application and progress of the virtual reality (VR) technique. Lectures showed that the VR technique would impact and prompt the teaching, experiment, research and application of forensic pathology with the development of operation guiding system, virtual autopsy, micro-imaging technique. Because of the limitation of software, hardware and the expense, the VR technique needed to be improved and perfected.

  17. Dancers' Application of the Alexander Technique

    ERIC Educational Resources Information Center

    Fortin, Sylvie; Girard, Fernande

    2005-01-01

    This qualitative study describes the experience of professional contemporary dancers studying and applying the Alexander Technique to their dancing. This study was motivated by: 1. years of teaching both dance and somatics, 2. a strong desire to better understand how the Alexander Technique can be applied by dancers, and 3. a gap that the…

  18. Dancers' Application of the Alexander Technique

    ERIC Educational Resources Information Center

    Fortin, Sylvie; Girard, Fernande

    2005-01-01

    This qualitative study describes the experience of professional contemporary dancers studying and applying the Alexander Technique to their dancing. This study was motivated by: 1. years of teaching both dance and somatics, 2. a strong desire to better understand how the Alexander Technique can be applied by dancers, and 3. a gap that the…

  19. Two-dimensional countercurrent chromatography×high performance liquid chromatography with heart-cutting and stop-and-go techniques for preparative isolation of coumarin derivatives from Peucedanum praeruptorum Dunn.

    PubMed

    Liu, Jing-Lan; Wang, Xin-Yuan; Zhang, Ling-Ling; Fang, Mei-Juan; Wu, Yun-Long; Wu, Zhen; Qiu, Ying-Kun

    2014-12-29

    Pure compounds isolated from complex natural plants are important for drug discovery. This study describes a novel two-dimensional hyphenation of counter-current chromatography and high-performance liquid chromatography (2D CCC×HPLC) with heart-cutting and stop-and-go techniques for preparative isolation of multiple targets components from Peucedanum praeruptorum Dunn (Umbelliferae) crude extracts in a single step. The CCC and HPLC were hyphenated via a 4-port valve equipped at the post-end of the CCC column, to heart cut the impure fractions to the 2nd dimensional HPLC for further separation. Furthermore, the stop-and-go flow scheme was applied in the 1st dimensional CCC to fit with the time constraints of the 2nd dimensional preparative HPLC. Last but not least, an optimal biphasic solvent system composed of n-heptane/acetone/water (31:50:19, v/v/v) with suitable Kd values and a higher retention of the stationary phase was chosen to separate target compounds, resulting in the improvement of the CCC column efficiency. By taking the advantages of this rationally designed system, sixteen coumarins were isolated from 1.0g of P. praeruptorum crude extract, with HPLC purity from 90.1% to 99.5%, in a single 2D separation run. More interestingly, two minor linear coumarins and one angular coumarin were isolated from P. praeruptorum Dunn for the first time. As far as we known, this is the first report on the combination of heart-cutting technique and stop-and-go protocol in 2D CCC×HPLC system, by which good separations on comprehensive matrix were achieved. We expect that this approach may have broad applications for simultaneous isolation and purification of multiple components from other complex plant-derived natural products.

  20. A study of some practical aspects of high temperature liquid chromatography in pharmaceutical applications.

    PubMed

    Berta, Renáta; Babják, Mónika; Gazdag, Mária

    2011-02-20

    In the pharmaceutical industry fast and efficient separation techniques play an increasing role among analytical methods because the samples to be investigated grow both in complexity and number, and there is an increasing time pressure to complete the analysis. Reducing the analysis time without decreasing the efficiency is possible using higher pressures, elevated temperatures, smaller particle sizes, or a combination of these approaches. Recently developed chromatographic techniques such as the UHPLC (ultra high performance liquid chromatography) and HTLC (high temperature liquid chromatography) are highly promising in meeting these demands. In this study, high temperature liquid chromatography (HTLC) with a zirconia-based column and temperatures elevated up to 150°C was used. We investigated the chromatographic behaviour of a steroid active pharmaceutical ingredient (levonorgestrel) and its structurally related impurities as model compounds. The effect of the temperature in the range of 50-150°C and the flow-rate in the range of 0.5-3.0 ml/min, and using methanol as an organic modifier, were studied for optimisation of the separation method. Copyright © 2010 Elsevier B.V. All rights reserved.

  1. ION-pair liquid chromatography technique for the estimation of metformin in its multicomponent dosage forms.

    PubMed

    Vasudevan, M; Ravi, J; Ravisankar, S; Suresh, B

    2001-04-01

    A simple, precise and accurate high performance liquid chromatography (HPLC) method was developed for the simultaneous estimation of metformin with gliclazide and glipizide present in multicomponent dosage forms. The method was carried out on Inertsil C(18) column. A mobile phase composed of acetonitrile-water containing camphor sulphonic acid (adjusted to pH 7 using 0.1 N sodium hydroxide; 75 mM) at a flow rate of 1 ml min(-1) was used for the separation. Detection was carried out at 225 nm. Tolbutamide was used as internal standard. Validation of the developed HPLC method was carried out.

  2. Development of techniques for complex mixture analysis by means of gas chromatography/triple quadrupole mass spectrometry

    SciTech Connect

    Schubert, A.J.

    1988-01-01

    Current technology in several phases of organic mixture analysis have been integrated to demonstrate the analytical power of the combined technique of gas chromatography/triple quadrupole mass spectrometry (GC/TQMS). This research has included capillary gas chromatography, chemical ionization, triple quadrupole mass spectrometry, and the high speed instrument control and data systems which are required to make such a powerful instrument feasible. The feasibility of GC/TQMS was enhanced by an increase in overall system speed and the development of programs to allow trace-level targeted component analyses on time variant samples introduced via the gas chromatograph. The performance of the instrument control system was achieved by dividing instrument control tasks among multiple processors rather than by increasing the power of the processor being used. Methanol chemical ionization was investigated as a tool for the mass spectrometric determination of trace level polar components in petroleum products. Results from this study indicate that methanol enhances both the selectivity and sensitivity of the ionization when compared to the more conventional technique of methane chemical ionization. Studies on the effect of varying the pressure of the methanol reagent demonstrated a simple approach through which the analyst can adjust both the sensitivity and selectivity of the ionization. Detection limits were determined for the determination of several thiophenes in a commercial jet aviation fuel by means of GC/TQMS. The combined use of capillary gas chromatography, methanol chemical ionization, and TQMS with specialized data acquisition programs, enabled the detection of these targeted components down to the low parts per million.

  3. Recent trends in application of multivariate curve resolution approaches for improving gas chromatography-mass spectrometry analysis of essential oils.

    PubMed

    Jalali-Heravi, Mehdi; Parastar, Hadi

    2011-08-15

    Essential oils (EOs) are valuable natural products that are popular nowadays in the world due to their effects on the health conditions of human beings and their role in preventing and curing diseases. In addition, EOs have a broad range of applications in foods, perfumes, cosmetics and human nutrition. Among different techniques for analysis of EOs, gas chromatography-mass spectrometry (GC-MS) is the most important one in recent years. However, there are some fundamental problems in GC-MS analysis including baseline drift, spectral background, noise, low S/N (signal to noise) ratio, changes in the peak shapes and co-elution. Multivariate curve resolution (MCR) approaches cope with ongoing challenges and are able to handle these problems. This review focuses on the application of MCR techniques for improving GC-MS analysis of EOs published between January 2000 and December 2010. In the first part, the importance of EOs in human life and their relevance in analytical chemistry is discussed. In the second part, an insight into some basics needed to understand prospects and limitations of the MCR techniques are given. In the third part, the significance of the combination of the MCR approaches with GC-MS analysis of EOs is highlighted. Furthermore, the commonly used algorithms for preprocessing, chemical rank determination, local rank analysis and multivariate resolution in the field of EOs analysis are reviewed.

  4. A Review on Recent Applications of High-Performance Liquid Chromatography in Metal Determination and Speciation Analysis.

    PubMed

    Rekhi, Heena; Rani, Susheela; Sharma, Neha; Malik, Ashok Kumar

    2017-06-23

    High-performance liquid chromatography (HPLC) has several advantages over the conventional methods due to their operational simplicity. It is a vital tool to determine metal ions having same mass but different electronic configuration, to separate complex mixtures and to resolve ions that may be indistinguishable by mass spectrometry alone. Metal ions play vital role in many biological processes and involved in setting up of many diseases. Therefore, the development of simple methods for the detection and quantification of metals in real samples might serve as diagnostic tools for various diseases. This review article focuses on the recent main feature of this technique, i.e. speciation of metal ions and their applications to series of problem of metal ion chemistry in different environmental matrixes. Speciation of metals is of increasing interest and has a great importance because of bioavailability, environmental mobility, toxicity and potential risk of metals. With the capability of partitioning the complex species of different metal ions, HPLC is an efficient technique for this task. This review summarizes recent advances in the development of HPLC to the fundamental understanding of metal ion chemistry in the environment and discusses all the issues that still need a lot of consideration. It has been classified into different sections depending on the role of HPLC in separation used and metal speciation; furthermore, the underlying sample preconcentration techniques and detection systems involved for the determination of metal ions and their applications were discussed.

  5. Advances in analytical techniques for neutron capture therapy: thin layer chromatography matrix and track etch thin layer chromatography methods for boron-10 analysis

    SciTech Connect

    Schremmer, J.M.; Noonan, D.J.

    1987-09-01

    A new track etch autoradiographic technique for quantitating boron-10 containing compounds used for neutron capture therapy is described. Instead of applying solutions of Cs2B12H11SH and its oxidation products directly to solid-state nuclear track detectors, diethylaminoethyl cellulose thin layer chromatography (TLC) plates are utilized as sample matrices. The plates are juxtaposed with Lexan polycarbonate detectors and irradiated in a beam of thermal neutrons. The detectors are then chemically etched, and the resultant tracks counted with an optoelectronic image analyzer. Sensitivity to boron-10 in solution reaches the 1 pg/microliter level, or 1 ppb. In heparinized blood samples, 100 pg boron-10/microliter are detected. This TLC matrix method has the advantage that sample plates can be reanalyzed under different reactor conditions to optimize detector response to the boron-10 carrier material. Track etch/TLC allows quantitation of the purity of boron neutron capture therapy compounds by utilizing the above method with TLC plates developed in solvent systems that resolve Cs2B12H11SH and its oxidative analogs. Detectors irradiated in juxtaposition to the thin layer chromatograms are chemically etched, and the tracks are counted in the sample lane from the origin of the plate to the solvent front. A graphic depiction of the number of tracks per field yields a quantitative analysis of compound purity.

  6. Application of immobilized enzyme reactor in on-line high performance liquid chromatography: a review.

    PubMed

    Girelli, Anna Maria; Mattei, Enrico

    2005-05-05

    This review summarizes all the research efforts in the last decade (1994-2003) that have been spent to the various application of immobilized enzyme reactor (IMER) in on-line high performance liquid chromatography (HPLC). All immobilization procedures including supports, kind of assembly into chromatographic system and methods are described. The effect of immobilization on enzymatic properties and stability of biocatalysts is considered. A brief survey of the main applications of IMER both as pre-column, post-column or column in the chemical, pharmaceutical, clinical and commodities fields is also reported.

  7. Application of Headspace Solid Phase Microextraction and Gas Chromatography/Mass Spectrometry for Rapid Detection of the Chemical Warfare Agent Sulfur Mustard

    DTIC Science & Technology

    2002-05-16

    Title of Thesis: “Application of Headspace Solid Phase Microextraction and Gas Chromatography/Mass Spectrometry for Rapid...TITLE AND SUBTITLE Application of Headspace Solid Phase Microextraction and Gas Chromatography/Mass Spectrometry for Rapid Detection of the Chemical...phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS). Five commercially available SPME fibers were investigated to determine the

  8. Investigation of liquid and gas chromatography techniques for separation of diastereomers of beta-(alpha-methylbenzyl) amino isobutyric acid.

    PubMed

    Held, Charles B; Robbins, David K

    2003-09-01

    Cryptophycins are macrolides investigated as potential anticancer agents. These large cyclic molecules are generated via a convergent process, utilizing the coupling of several smaller fragments synthesized individually. During early synthetic development of the beta-amino acid fragment C, analytical methods are necessary for the characterization of products resulting from the various routes being studied. One route being evaluated produces (RR) and (RS) diastereomers of beta-(alpha-methylbenzyl) amino isobutyric acid as intermediates. To measure diastereomeric excess (%de), assay conditions using high-performance liquid chromatography (HPLC) and capillary gas chromatographic (GC) techniques are explored. Derivatization methods using trifluoroacetyl- and silyl-derivatives are investigated for use with capillary GC. The results of the GC investigations are found to be only partially successful. Ion-pair HPLC is determined to be the optimal technique, utilizing pentanesulfonic acid as the counter ion to the amine group of beta-(alpha-methylbenzyl) amino isobutyric acid.

  9. Identification of wood between Phoebe zhennan and Machilus pingii using the gas chromatography-mass spectrometry direct injection technique.

    PubMed

    Xu, Bin; Zhu, Tao; Li, Jingya; Liu, Shuai

    2013-01-01

    In this paper, the technique of direct injection gas chromatography-mass spectrometer (GC-MS) was employed to discriminate between two batches of wood (Phoebe zhennan and Machilus pingii) with characteristic smells. Based on the GC-MS fingerprints obtained, similarities between samples were evaluated via correlation coefficient, hierarchical clustering and characteristic constituents analysis. The results showed that distinct differences in total ion chromatograms existed between the two species of wood and their correlation coefficients were low; however, the relationship between the same species of different batches showed the opposite; meanwhile, the analysis of hierarchical clustering and characteristic constituents also demonstrated an interrelationship. All the analytical methods achieved the goal of identification between the two species of wood, which verified that the technique can be used to identify different species of wood with characteristic smells.

  10. 48 CFR 9904.417-50 - Techniques for application.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 7 2010-10-01 2010-10-01 false Techniques for application... ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.417-50 Techniques for application. (a) The cost of money... capitalized, such as the method used for financial accounting and reporting, may be used, provided...

  11. 48 CFR 9904.401-50 - Techniques for application.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 7 2010-10-01 2010-10-01 false Techniques for application. 9904.401-50 Section 9904.401-50 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD... ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.401-50 Techniques for application. (a) The standard...

  12. 48 CFR 9904.404-50 - Techniques for application.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 7 2010-10-01 2010-10-01 false Techniques for application. 9904.404-50 Section 9904.404-50 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD... ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.404-50 Techniques for application. (a) The cost to...

  13. 48 CFR 9904.402-50 - Techniques for application.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 7 2010-10-01 2010-10-01 false Techniques for application. 9904.402-50 Section 9904.402-50 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD... ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.402-50 Techniques for application. (a) The Fundamental...

  14. 48 CFR 9904.403-50 - Techniques for application.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 7 2010-10-01 2010-10-01 false Techniques for application. 9904.403-50 Section 9904.403-50 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD... ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.403-50 Techniques for application. (a)(1) Separate...

  15. 48 CFR 9904.406-50 - Techniques for application.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 7 2010-10-01 2010-10-01 false Techniques for application. 9904.406-50 Section 9904.406-50 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD... ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.406-50 Techniques for application. (a) The cost of an...

  16. 48 CFR 9904.405-50 - Techniques for application.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 7 2010-10-01 2010-10-01 false Techniques for application. 9904.405-50 Section 9904.405-50 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD... ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.405-50 Techniques for application. (a) The detail and...

  17. Fluorescence Lifetime Techniques in Medical Applications

    PubMed Central

    Marcu, Laura

    2012-01-01

    This article presents an overview of time-resolved (lifetime) fluorescence techniques used in biomedical diagnostics. In particular, we review the development of time-resolved fluorescence spectroscopy (TRFS) and fluorescence lifetime imaging (FLIM) instrumentation and associated methodologies which allows for in vivo characterization and diagnosis of biological tissues. Emphasis is placed on the translational research potential of these techniques and on evaluating whether intrinsic fluorescence signals provide useful contrast for the diagnosis of human diseases including cancer (gastrointestinal tract, lung, head and neck, and brain), skin and eye diseases, and atherosclerotic cardiovascular disease. PMID:22273730

  18. Application of GPC/LALLS to cellulose research. [Gel permeation chromatography/low-angle laser light scattering

    SciTech Connect

    Cael, J.J.; Cietek, D.J.; Kolpak, F.J.

    1983-01-01

    The techniques of gel permeation chromatography and low-angle laser light scattering (GPC/LALLS) have been combined for absolute determination of cellulose molecular weights and molecular weight distributions (MWD). The GPC/LALLS technique has been applied to tetrahydrofuran (THF) solutions of cellulose tricarbanilate (CTC) derivatives prepared from celluloses having a wide range of molecular weights. The molecular weight data obtained are consistent with values determined by intrinsic viscosity methods; and as a consequence of the absolute nature of this technique, Mark-Houswink coefficients can be predicted from a single, broad-distribution, linear homopolymer without recourse to tedious and time-consuming fractional precipitation methods. A unique application of the technique has been in correlating GPC/LALLS molecular weight data with the viscosity of nonderivatized celluloses dissolved in 0.5 M cupiethylenediamine hydroxide (CuEn). The procedure yields an absolute viscosity-molecular weight relationship which is comparable with a similar relationship originally derived from cellulose nitrates. The results indicate that the weight-average degree of polymerization (DP/sub w/) for CTC preparations is considerably greater than that obtained from cellulose nitrates, and this discrepancy, in DP/sub w/ has been attributed to errors in the Mark-Houwink coefficients for the cellulose nitrate-acetone system. 25 references, 9 figures, 7 tables.

  19. 48 CFR 9905.505-50 - Techniques for application.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 7 2010-10-01 2010-10-01 false Techniques for application... ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS FOR EDUCATIONAL INSTITUTIONS 9905.505-50 Techniques for... any less formal cost accounting techniques which establishes and maintains adequate cost...

  20. Spectrofluorometer techniques applicable to sample surfaces

    NASA Technical Reports Server (NTRS)

    Stoertz, G. E.

    1972-01-01

    Methods for correcting fluorescence spectra to remove instrumental artifacts are described, including computational and graphical procedures for rapid manual correction by nomographs and similar techniques. Expedient methods for the selection and use of optical filters, the evaluation of filter effectiveness, and the selection of optimum wavelength settings in spectrofluorometry are outlined.

  1. Discrimination of honeys using colorimetric sensor arrays, sensory analysis and gas chromatography techniques.

    PubMed

    Tahir, Haroon Elrasheid; Xiaobo, Zou; Xiaowei, Huang; Jiyong, Shi; Mariod, Abdalbasit Adam

    2016-09-01

    Aroma profiles of six honey varieties of different botanical origins were investigated using colorimetric sensor array, gas chromatography-mass spectrometry (GC-MS) and descriptive sensory analysis. Fifty-eight aroma compounds were identified, including 2 norisoprenoids, 5 hydrocarbons, 4 terpenes, 6 phenols, 7 ketones, 9 acids, 12 aldehydes and 13 alcohols. Twenty abundant or active compounds were chosen as key compounds to characterize honey aroma. Discrimination of the honeys was subsequently implemented using multivariate analysis, including hierarchical clustering analysis (HCA) and principal component analysis (PCA). Honeys of the same botanical origin were grouped together in the PCA score plot and HCA dendrogram. SPME-GC/MS and colorimetric sensor array were able to discriminate the honeys effectively with the advantages of being rapid, simple and low-cost. Moreover, partial least squares regression (PLSR) was applied to indicate the relationship between sensory descriptors and aroma compounds. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Determination of fluoxetine enantiomers in pharmaceutical formulations by electrokinetic chromatography-counter current technique.

    PubMed

    Asensi-Bernardi, Lucía; Martín-Biosca, Yolanda; Fornet-Herrero, Eder; Sagrado, Salvador; Medina-Hernández, María José

    2013-03-01

    In this work, an electrokinetic chromatography-counter current procedure for the separation of fluoxetine enantiomers using highly sulfated β-cyclodextrin was optimized and applied to the determination of the enantiomers in three pharmaceutical formulations according to the matrix features. Quality criteria were applied to facilitate its transferability to testing laboratories. Fluoxetine was used therapeutically as the racemate, although a stereospecificity associated with its interactions with the neuronal serotonin-uptake carrier was demonstrated. In this context, the development of enantioselective methods for the chiral analysis of pharmaceuticals allowing stereoisomer ratio estimations has increasing interest in pharmaceutical industry. The proposed method allows the quantification of both enantiomers in less than 2 min with high resolution (R(s) = 2.4).

  3. Quantification of aroma compounds in Parmigiano Reggiano cheese by a dynamic headspace gas chromatography-mass spectrometry technique and calculation of odor activity value.

    PubMed

    Qian, Michael; Reineccius, G A

    2003-03-01

    Potentially important aroma compounds in Parmigiano Reggiano cheese were quantified. Free fatty acids were isolated with ion-exchange chromatography and quantified by gas chromatography. Neutral aroma compounds were quantified with a purge-trap/gas chromatography-mass spectrometry with selective mass ion technique. Odor activity values were calculated based on sensory thresholds reported in literature. The calculated odor activity values suggest that 3-methylbutanal, 2-methylpropanal, 2-methylbutanal, dimethyl trisulfide, diacetyl, methional, phenylacetaldehyde, ethyl butanoate, ethyl hexanoate, ethyl octanoate, acetic, butanoic, hexanoic, and octanoic acids are the most important aroma contributors to Parmigiano Reggiano cheese.

  4. Fundamental aspects of chiral electromigration techniques and application in pharmaceutical and biomedical analysis.

    PubMed

    Scriba, Gerhard K E

    2011-06-25

    Capillary electromigration techniques are often considered ideal methods for the analysis of chiral compounds due to the high resolution power and flexibility of the technique. Therefore, especially capillary electrophoresis using a chiral selector in the background electrolyte, also termed electrokinetic chromatography, has found widespread acceptance in analytical enantioseparations of drug compounds in pharmaceuticals and biological media. Moreover, mechanistic studies on analyte complexation by the chiral selectors have continuously been conducted in an effort to rationalize enantioseparation phenomena. These studies combined capillary electrophoresis with spectroscopic techniques such as nuclear magnetic resonance and/or molecular modeling. The present review focuses on recent examples of mechanistic aspects of capillary electromigration enantioseparations and summarizes recent applications of chiral pharmaceutical and biomedical analysis published between January 2009 and August 2010. Copyright © 2010 Elsevier B.V. All rights reserved.

  5. Moire Ct technique and its application on laser flexible manufacture

    NASA Astrophysics Data System (ADS)

    Li, Tianze; Hou, Luan; Jiang, Chuan; Zhang, Xia

    2010-10-01

    In the paper, the main properties of Moire fringe, such as average effect, amplification effect, corresponding relation are elaborated, and the principle of Moire Ct technique is represented. On the basis of main features of Moire fringe, multidirectional Moire Ct deflection system is designed using high accuracy Ccd, grating, filter, lens, planar mirror and optical splitter. The system has simple light path, and can be easily made into the one that has large caliber.It can analyze multidirectional records of the probe at the same time, and can obtain clear interference patterns.The iterative technique combined with computer chromatography algorithms is used to achieve inversion of multidirectional clear interference patterns so that the required parameters can be acquired. Moire Ct technique is applied to laser flexible manufacture. Produced parts are delaminated on the paper, and are stratified manufactured until they are connected to forming. Cad/Cam system is adopted to construct Spatial three-dimensional geometric model, and the data files are formed. Then by using the Small triangle plane, the inner and outer surfaces of the data files are discretized. Discretized parts model is made chromatography with mathematical methods using Cam software. A series of parallel horizontal intersecting planes are generated. The problems of filtering arrangement tangent points are solved by recombining the shape and structure relationship among the triangular mesh. Several conclusions are presented.

  6. Experimental Techniques Applicable to Turbulent Flows.

    DTIC Science & Technology

    1977-01-01

    dent laser , and Stokesplier, e the electron charge, R the load radiation respectively, I ~, is the co— resistance , E the energy of the scattered... measurements of methane , Sca ttering of a Laser Beam ”, A IAA J. 9— using the spontaneous Ramars effect and the 1971., PIBAL Rep. No. 69—46, Nov...developed Laser Raman and of several species of interest in a flame, Laser Doppler techniques may be ideally their individual temperatures as well as

  7. An overview of heat exchanger enhancement techniques for industrial applications

    SciTech Connect

    Somasundaram, S.; Ohadi, M.M.; Richlen, S.

    1992-06-01

    An assessment is make of selected currently available heat exchanger enhancement techniques for single- and two-phase heat transfer mechanisms to determine their practicality and commercialization potential for different industrial applications. The assessment includes a screening review of the major techniques being investigated in the research community, and identification of selected passive techniques and determine their potential limitations with respect to industrial applications. A more detailed study of the research needs and the technology gaps is being conducted to address the issues of concern for each practical application of the chosen techniques. The technical and economic feasibility and the performance benefits of incorporating a particular technique in a heat transfer process is also discussed. The potential design, operational, and manufacturing cost issues that have prevented a technique from being widely commercialized are identified.

  8. Layered classification techniques for remote sensing applications

    NASA Technical Reports Server (NTRS)

    Swain, P. H.; Wu, C. L.; Landgrebe, D. A.; Hauska, H.

    1975-01-01

    The single-stage method of pattern classification utilizes all available features in a single test which assigns the unknown to a category according to a specific decision strategy (such as the maximum likelihood strategy). The layered classifier classifies the unknown through a sequence of tests, each of which may be dependent on the outcome of previous tests. Although the layered classifier was originally investigated as a means of improving classification accuracy and efficiency, it was found that in the context of remote sensing data analysis, other advantages also accrue due to many of the special characteristics of both the data and the applications pursued. The layered classifier method and several of the diverse applications of this approach are discussed.

  9. Application of data mining techniques in pharmacovigilance.

    PubMed

    Wilson, Andrew M; Thabane, Lehana; Holbrook, Anne

    2004-02-01

    To discuss the potential use of data mining and knowledge discovery in databases for detection of adverse drug events (ADE) in pharmacovigilance. A literature search was conducted to identify articles, which contained details of data mining, signal generation or knowledge discovery in relation to adverse drug reactions or pharmacovigilance in medical databases. ADEs are common and result in significant mortality, and despite existing systems drugs have been withdrawn due to ADEs many years after licensing. Knowledge discovery in databases (KDD) is a technique which may be used to detect potential ADEs more efficiently. KDD involves the selection of data variables and databases, data preprocessing, data mining and data interpretation and utilization. Data mining encompasses a number of statistical techniques including cluster analysis, link analysis, deviation detection and disproportionality assessment which can be utilized to determine the presence of and to assess the strength of ADE signals. Currently the only data mining methods to be used in pharmacovigilance are those of disproportionality, such as the Proportional Reporting Ratio and Information Component, which have been used to analyse the UK Yellow Card Scheme spontaneous reporting database and the WHO Uppsala Monitoring Centre database. The association of pericarditis with practolol but not with other beta-blockers, the association of captopril and other angiotensin-converting enzymes with cough, and the association of terfenadine with heart rate and rhythm disorders could be identified by mining the WHO database. In view of the importance of ADEs and the development of massive data storage systems and powerful computer systems, the use of data mining techniques in knowledge discovery in medical databases is likely to be of increasing importance in the process of pharmacovigilance as they are likely to be able to detect signals earlier than using current methods.

  10. Determination of organophosphorus pesticides by gas chromatography with mass spectrometry using a large-volume injection technique after magnetic extraction.

    PubMed

    Nedaei, Maryam; Salehpour, Ali-Reza; Mozaffari, Shahla; Yousefi, Seyedeh Mahboobeh; Yousefi, Seyed Reza

    2014-09-01

    A fast and efficient method was developed for the extraction and determination of organophosphorus pesticides in water samples. Organophosphorus pesticides were extracted by solid-phase extraction using magnetic multi-walled carbon nanotubes and determined by gas chromatography with ion-trap mass spectrometry. Parameters affecting the extraction were investigated. Under optimum conditions of the method, 10 mg magnetic multi-walled carbon nanotubes were added into 10 mL sample. After 2 min, adsorbent particles settled at the bottom of test tube with a magnet. After removing aqueous supernatant, the analytes were desorbed with acetonitrile. Then, 70 μL of acetonitrile phase was injected into the gas chromatography and mass spectrometry system that had an ion-trap analyzer. To achieve high sensitivity, the large-volume-injection technique was used with a programmed temperature vaporization inlet, and the ion-trap mass spectrometer was operated in single ion storage mode. Under the best conditions, the enrichment factors and extraction recoveries were in the range of 113-124 and 74-103%, respectively. The limits of detection were between 3 and 15 ng/L, and the relative standard deviations were < 10%. This method was successfully used for the determination of organophosphorus pesticides in dam water, lagoon water, and river water samples with good reproducibility and recovery.

  11. Gradient enhanced-fluidity liquid hydrophilic interaction chromatography of ribonucleic acid nucleosides and nucleotides: A "green" technique.

    PubMed

    Beilke, Michael C; Beres, Martin J; Olesik, Susan V

    2016-03-04

    A "green" hydrophilic interaction liquid chromatography (HILIC) technique for separating the components of mixtures with a broad range of polarities is illustrated using enhanced-fluidity liquid mobile phases. Enhanced-fluidity liquid chromatography (EFLC) involves the addition of liquid CO2 to conventional liquid mobile phases. Decreased mobile phase viscosity and increased analyte diffusivity results when a liquefied gas is dissolved in common liquid mobile phases. The impact of CO2 addition to a methanol:water (MeOH:H2O) mobile phase was studied to optimize HILIC gradient conditions. For the first time a fast separation of 16 ribonucleic acid (RNA) nucleosides/nucleotides was achieved (16min) with greater than 1.3 resolution for all analyte pairs. By using a gradient, the analysis time was reduced by over 100% compared to similar separations conducted under isocratic conditions. The optimal separation using MeOH:H2O:CO2 mobile phases was compared to MeOH:H2O and acetonitrile:water (ACN:H2O) mobile phases. Based on chromatographic performance parameters (efficiency, resolution and speed of analysis) and an assessment of the environmental impact of the mobile phase mixtures, MeOH:H2O:CO2 mixtures are preferred over ACN:H2O or MeOH:H2O mobile phases for the separation of mixtures of RNA nucleosides and nucleotides. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Inverse Raman effect: applications and detection techniques

    SciTech Connect

    Hughes, L.J. Jr.

    1980-08-01

    The processes underlying the inverse Raman effect are qualitatively described by comparing it to the more familiar phenomena of conventional and stimulated Raman scattering. An experession is derived for the inverse Raman absorption coefficient, and its relationship to the stimulated Raman gain is obtained. The power requirements of the two fields are examined qualitatively and quantitatively. The assumption that the inverse Raman absorption coefficient is constant over the interaction length is examined. Advantages of the technique are discussed and a brief survey of reported studies is presented.

  13. Pinna synthetic mold for otoplasty techniques application.

    PubMed

    Reis, Mariah Guieiro Alves Dos; Marim, Ricardo Guimarães; Souto, Luis Ricardo Martinhão

    2017-02-14

    The ear deformity Tanzer type V, also known as prominent ears, is the most common genetic defect of the pinna. The surgery designed for its correction is known as otoplasty. This esthetic surgery can be performed using different techniques, which requires great skill of its operator. The purpose of this work is the development of a new tool for otoplasty techniques training, aimed on the possibility to minimize errors during the otoplasty. Synthetic molds of the external ear from patients with Tanzer type V deformity were made, using silicone material and Rayon. The main procedures of otoplasty could be performed in the molds made of silicone and Rayon with a good esthetic result. The elaborated molds had identical size and shape of a human ear and could be positioned in the same shape of the patient ears. Thus, the synthetic molds were presented as promising simulation tools for the training and surgical enhancement of otoplasty, especially for doctors beginners. Copyright © 2017 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

  14. Survey of benzene in foods by using headspace concentration techniques and capillary gas chromatography.

    PubMed

    McNeal, T P; Nyman, P J; Diachenko, G W; Hollifield, H C

    1993-01-01

    Recently, the combination of sodium or potassium benzoate with ascorbic acid was shown to produce low levels (ng/g) of benzene in fruit-flavored soft drinks. The presence of benzene also was reported in butter, eggs, meat, and certain fruits; levels of these findings ranged from 0.5 ng/g in butter to 500-1900 ng/g in eggs. Because benzoates are widely used as food preservatives, a limited survey of other foods containing added benzoate salts was conducted to investigate the potential for benzene formation. Selected foods that did not contain added benzoates but were previously reported to contain benzene were analyzed for comparison. More than 50 foods were analyzed by purge-and-trap or static headspace concentration and capillary gas chromatography. Benzene was quantitated by using the method of standard additions, and its identity was confirmed by mass selective detection. Results of this limited survey show that foods without added benzoates (including eggs) contained benzene at levels equal to or less than 2 ng/g. Slightly higher levels were present in some foods and beverages containing both ascorbic acid and sodium benzoate.

  15. Determination of Synthetic Cathinones in Urine Using Gas Chromatography-Mass Spectrometry Techniques.

    PubMed

    Hong, Wei-Yin; Ko, Ya-Chun; Lin, Mei-Chih; Wang, Po-Yu; Chen, Yu-Pen; Chiueh, Lih-Ching; Shih, Daniel Yang-Chih; Chou, Hsiu-Kuan; Cheng, Hwei-Fang

    2016-01-01

    In recent years, the abuse of synthetic cathinones has increased considerably. This study proposes a method, based on gas chromatography/mass spectrometry (GC-MS), to analyze and quantify six synthetic cathinones in urine samples: mephedrone (4-MMC), methylone (bk-MDMA), butylone, ethylone, pentylone and methylenedioxypyrovalerone (MDPV). In our procedure, the urine samples undergo solid-phase extraction (SPE) and derivatization prior to injection into the GC-MS device. Separation is performed using a HP-5MS capillary column. The use of selective ion monitoring (SIM mode) makes it is good sensitivity in this method, and the entire analysis process is within 18 min. In addition, the proposed method maintains linearity in the calibration curve from 50 to 2,000 ng/mL (r(2) > 0.995). The limit of detection of this method is 5 ng/mL, with the exception of MDPV (20 ng/mL); the limit of quantification is 20 ng/mL, with the exception of MDPV (50 ng/mL). In testing, the extraction performance of SPE was between 82.34 and 104.46%. Precision and accuracy results were satisfactory <15%. The proposed method was applied to six real urine samples, one of which was found to contain 4-MMC and bk-MDMA. Our results demonstrate the efficacy of the proposed method in the identification of synthetic cathinones in urine, with regard to the limits of detection and quantification. This method is highly repeatable and accurate.

  16. Expanded separation technique for chlorophyll metabolites in Oriental tobacco leaf using non aqueous reversed phase chromatography.

    PubMed

    Ishida, Naoyuki

    2011-08-26

    An improved separation method for chlorophyll metabolites in Oriental tobacco leaf was developed. While Oriental leaf still gives the green color even after the curing process, little attention has been paid to the detailed composition of the remaining green pigments. This study aimed to identify the green pigments using non aqueous reversed phase chromatography (NARPC). To this end, liquid chromatograph (LC) equipped with a photo diode array detector (DAD) and an atmospheric pressure chemical ionization/mass spectrometer (APCI/MSD) was selected, because it is useful for detecting low polar non-volatile compounds giving green color such as pheophytin a. Identification was based on the wavelength spectrum, mass spectrum and retention time, comparing the analytes in Oriental leaf with the commercially available and synthesized components. Consequently, several chlorophyll metabolites such as hydroxypheophytin a, solanesyl pheophorbide a and solanesyl hydroxypheophorbide a were newly identified, in addition to typical green pigments such as chlorophyll a and pheophytin a. Chlorophyll metabolites bound to solanesol were considered the tobacco specific components. NARPC expanded the number of detectable low polar chlorophyll metabolites in Oriental tobacco leaf.

  17. Valid internal standard technique for arson detection based on gas chromatography-mass spectrometry.

    PubMed

    Salgueiro, Pedro A S; Borges, Carlos M F; Bettencourt da Silva, Ricardo J N

    2012-09-28

    The most popular procedures for the detection of residues of accelerants in fire debris are the ones published by the American Society for Testing and Materials (ASTM E1412-07 and E1618-10). The most critical stages of these tests are the conservation of fire debris from the sampling to the laboratory, the extraction of residues of accelerants from the debris to the activated charcoal strips (ACS) and from those to the final solvent, as well as the analysis of sample extract by gas chromatography-mass spectrometry (GC-MS) and the interpretation of the instrumental signal. This work proposes a strategy for checking the quality of the sample conservation, the accelerant residues transference to final solvent and GC-MS analysis, using internal standard additions. It is used internal standards ranging from a highly volatile compound for checking debris conservation to low volatile compound for checking GC-MS repeatability. The developed quality control (QC) parameters are not affected by GC-MS sensitivity variation and, specifically, the GC-MS performance control is not affected by ACS adsorption saturation that may mask test performance deviations. The proposed QC procedure proved to be adequate to check GC-MS repeatability, ACS extraction and sample conservation since: (1) standard additions are affected by negligible uncertainty and (2) observed dispersion of QC parameters are fit for its intended use.

  18. Molecular authentication and quality control using a high performance liquid chromatography technique of Fructus Evodiae.

    PubMed

    Huang, Dan; Li, Shun Xiang; Cai, Guang Xian; Yue, Chun Hua; Wei, Li Jun; Zhang, Ping

    2008-02-01

    In present paper, the properties of molecular authentication combined with the fingerprints of high performance liquid chromatography (HPLC) were validated by analyzing ten batches of Fructus Evodiae samples (the dried nearly ripe fruit of Evodia rutaecarpa (JUSS.) BENTH., Evodia rutaecarpa (JUSS.) BENTH. var. officinalis (DODE) HUANG or Evodia rutaecarpa (JUSS.) BENTH. var. bodinieri (DODE) HUANG). The results of this investigation show that the similarities of internal transcribed spacer (ITS) sequences were almost 100% in Evodia rutaecarpa (JUSS.) BENTH. var. bodinieri (DODE) HUANG, 97% in Evodia rutaecarpa (JUSS.) BENTH., and 96% in Evodia rutaecarpa (JUSS.) BENTH. var. officinalis (DODE) HUANG. The percentage of identity between the two groups of Evodia rutaecarpa (JUSS.) BENTH. var. bodinieri (DODE) HUANG and Evodia rutaecarpa (JUSS.) BENTH. var. officinalis (DODE) HUANG is almost 96%, but the identity among the group of these three species is only 73%. The results show that Fructus Evodiae comes from three species respectively. The fingerprints of HPLC show that Fructus Evodiae revealed 20 major common peaks. And the three species have almost the same chemical constituents. ITS sequence fingerprint combining the fingerprint of HPLC can not only be developed to identify and distinguish the three species in detail, but also can be used for optimizing location where Fructus Evodiae has much higher bioactive constituents and yield.

  19. Laser induced fluorescence technique for environmental applications

    NASA Astrophysics Data System (ADS)

    Utkin, Andrei B.; Felizardo, Rui; Gameiro, Carla; Matos, Ana R.; Cartaxana, Paulo

    2014-08-01

    We discuss the development of laser induced fluorescence sensors and their application in the evaluation of water pollution and physiological status of higher plants and algae. The sensors were built on the basis of reliable and robust solid-state Nd:YAG lasers. They demonstrated good efficiency in: i) detecting and characterizing oil spills and dissolved organic matter; ii) evaluating the impact of stress on higher plants (cork oak, maritime pine, and genetically modified Arabidopsis); iii) tracking biomass changes in intertidal microphytobenthos; and iv) mapping macroalgal communities in the Tagus Estuary.

  20. Application of Ionic Liquids in High Performance Reversed-Phase Chromatography

    PubMed Central

    Wang, Ye; Tian, Minglei; Bi, Wentao; Row, Kyung Ho

    2009-01-01

    Ionic liquids, considered “green” chemicals, are widely used in many areas of analytical chemistry due to their unique properties. Recently, ionic liquids have been used as a kind of novel additive in separation and combined with silica to synthesize new stationary phase as separation media. This review will focus on the properties and mechanisms of ionic liquids and their potential applications as mobile phase modifier and surface-bonded stationary phase in reversed-phase high performance liquid chromatography (RP-HPLC). Ionic liquids demonstrate advantages and potential in chromatographic field. PMID:19582220

  1. Bile salt surfactants in micellar electrokinetic capillary chromatography: Application to hydrophobic molecule separations

    SciTech Connect

    Cole, R.O.; Sepaniak, M.J. . Dept. of Chemistry); Hinze, W.L. . Dept. of Chemistry); Gorse, J.; Oldiges, K. . Dept. of Chemistry)

    1990-01-01

    Bile Salt surfactants are used in the micellar electrokinetic capillary chromatography (MECC) separation of various hydrophobic compounds. The use of methanol in the mobile phase allows the separation of previously intractable compounds including polyaromatic hydrocarbons. The effects of methanol on critical micelle concentration is investigated for sodium dodecyl sulfate (SDS) and the bile salt sodium cholate. It is determined that the unique structure of the bile salt micelle is much more tolerant to the addition of organic solvents than SDS, thereby increasing the scope of applications of MECC to include hydrophobic compounds. 30 refs., 9 figs.

  2. Defectoscopic and Clinical Applications of Infrared Technique

    NASA Astrophysics Data System (ADS)

    Kopal, I.; Koštial, P.; Špička, I.; Pleva, L.; Jančíková, Z.

    2017-02-01

    The article deals with possible visualization of inhomogeneities in inorganic materials, such as laminates, as well as organic materials, such as bones. This work also provides a study of the visualization of internal fixation (nail), introduced in a bone by the IR technique. In the theoretical part, we present thermal wave propagation and a theoretical approach to the possibility of visualization of the boundary between two different materials with different thermal conductivity. Further on, the experimental method is tested with success on discovering artificial defects in glass laminates. In the second part of the article, a successful method of the visualization of the internal fixator position in a bone under IR excitation is presented. Methods of processing the data measured with the use of an infrared camera are presented in detail.

  3. Advanced analytical techniques for the extraction and characterization of plant-derived essential oils by gas chromatography with mass spectrometry.

    PubMed

    Waseem, Rabia; Low, Kah Hin

    2015-02-01

    In recent years, essential oils have received a growing interest because of the positive health effects of their novel characteristics such as antibacterial, antifungal, and antioxidant activities. For the extraction of plant-derived essential oils, there is the need of advanced analytical techniques and innovative methodologies. An exhaustive study of hydrodistillation, supercritical fluid extraction, ultrasound- and microwave-assisted extraction, solid-phase microextraction, pressurized liquid extraction, pressurized hot water extraction, liquid-liquid extraction, liquid-phase microextraction, matrix solid-phase dispersion, and gas chromatography (one- and two-dimensional) hyphenated with mass spectrometry for the extraction through various plant species and analysis of essential oils has been provided in this review. Essential oils are composed of mainly terpenes and terpenoids with low-molecular-weight aromatic and aliphatic constituents that are particularly important for public health. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Hybrid Grid Techniques for Propulsion Applications

    NASA Technical Reports Server (NTRS)

    Koomullil, Roy P.; Soni, Bharat K.; Thornburg, Hugh J.

    1996-01-01

    During the past decade, computational simulation of fluid flow for propulsion activities has progressed significantly, and many notable successes have been reported in the literature. However, the generation of a high quality mesh for such problems has often been reported as a pacing item. Hence, much effort has been expended to speed this portion of the simulation process. Several approaches have evolved for grid generation. Two of the most common are structured multi-block, and unstructured based procedures. Structured grids tend to be computationally efficient, and have high aspect ratio cells necessary for efficently resolving viscous layers. Structured multi-block grids may or may not exhibit grid line continuity across the block interface. This relaxation of the continuity constraint at the interface is intended to ease the grid generation process, which is still time consuming. Flow solvers supporting non-contiguous interfaces require specialized interpolation procedures which may not ensure conservation at the interface. Unstructured or generalized indexing data structures offer greater flexibility, but require explicit connectivity information and are not easy to generate for three dimensional configurations. In addition, unstructured mesh based schemes tend to be less efficient and it is difficult to resolve viscous layers. Recently hybrid or generalized element solution and grid generation techniques have been developed with the objective of combining the attractive features of both structured and unstructured techniques. In the present work, recently developed procedures for hybrid grid generation and flow simulation are critically evaluated, and compared to existing structured and unstructured procedures in terms of accuracy and computational requirements.

  5. Surface modification: advantages, techniques, and applications

    SciTech Connect

    Natesan, K.

    2000-03-01

    Adequate performance of materials at elevated temperatures is a potential problem in many systems within the chemical, petroleum, process, and power-generating industries. Degradation of materials occurs because of interaction between the structural material and the exposure environment. These interactions are generally undesired chemical reactions that can lead to accelerated wastage and alter the functional requirements and/or structural integrity of the materials. Therefore, material selection for high-temperature applications must be based not only on a material strength properties but also on resistance to the complex environments prevalent in the anticipated exposure environment. As plants become larger, the satisfactory performance and reliability of components play a greater role in plant availability and economics. However, system designers are becoming increasingly concerned with finding the least expensive material that will satisfactorily perform the design function for the desired service life. This present paper addresses the benefits of surface modification and identified several criteria for selection and application of modified surfaces in the power sector. A brief review is presented on potential methods for modification of surfaces, with the emphasis on coatings. In the final section of the paper, several examples address the requirements of different energy systems and surface modification avenues that have been applied to resolve the issues.

  6. Recent developments in sample preparation techniques for chromatography analysis of traditional Chinese medicines.

    PubMed

    Deng, Chunhui; Liu, Ning; Gao, Mingxia; Zhang, Xiangmin

    2007-06-15

    Traditional Chinese medicines (TCMs) have a long history dating back thousands of years. Recently, there has been increasing interest worldwide in the use of TCMs for the prevention and treatment of various illnesses. In China, a large number of analytical tools, especially chromatographic techniques have been used to analyze the constituents of TCMs in order to control their quality and discover new bioactive compounds. In this paper, recent developments in sample preparation techniques for the extraction, clean-up, and concentration of analytes from TCMs are compared. These techniques include headspace solid-phase microextraction (HS-SPME), headspace liquid-phase microextraction (HS-LPME), microwave-assisted extraction (MAE), supercritical-fluid extraction (SFE), pressurized-liquid extraction (PLE), and microwave distillation (MD).

  7. Autoregressive and bispectral analysis techniques: EEG applications.

    PubMed

    Ning, T; Bronzino, J D

    1990-01-01

    Some basic properties of autoregressive (AR) modeling and bispectral analysis are reviewed, and examples of their application in electroencephalography (EEG) research are provided. A second-order AR model was used to score cortical EEGs in order. In tests performed on five adult rats to distinguish between different vigilance states such a quiet-waking (QW), rapid-eye-movement (REM), and slow-wave sleep (SWS), SWS activity was correctly identified over 96% of the time, and a 95% agreement rate was achieved in recognizing the REM sleep stage. In a bispectral analysis of the rat EEG, third-order cumulant (TOC) sequences of 32 epochs belonging to the same vigilance state were estimated and then averaged. Preliminary results have shown that bispectra of hippocampal EEGs during REM Sleep exhibit significant quadratic phase couplings between frequencies in the 6-8-Hz range, associated with the theta rhythm.

  8. In vivo investigation of pharmacokinetics of model drug: comparison of near infrared technique with high-performance liquid chromatography

    NASA Astrophysics Data System (ADS)

    Gu, Yueqing; Liu, Fei; Fang, Chunsheng; Qian, Zhiyu; Achilefu, Samuel

    2010-02-01

    Near infrared spectroscopy possess great potential for in vivo quantitative monitoring of drugs in animal subject. The accuracy of the measurements by near infrared technique should be evaluated by an established method. In this study, a near infrared fluorescence dye, cypate and its conjugation cypate-PEG were used as model drug for in vivo dynamic study. The pharmacokinetics of the model drug in mice subjects were investigated by near infrared spectroscopy and high performance liquid chromatography, respectively. The results from the two techniques were compared. The pharmacokinetic parameters calculated based on the acquired data by DAS software showed that there were no statistical differences between the two methods. The dynamic distribution of the model drugs in mouse model imaged by NIR image system indicated that cypate firstly accumulated in liver and was cleared from the enteron system, while cypate - PEG clearance from the urine system. Results indicated that NIR monitoring technique provide a promising quantitative way for in vivo monitoring the dynamics of drugs in animal subjects.

  9. Application of hybrid LRR technique to protein crystallization.

    PubMed

    Jin, Mi Sun; Lee, Jie-Oh

    2008-05-31

    LRR family proteins play important roles in a variety of physiological processes. To facilitate their production and crystallization, we have invented a novel method termed "Hybrid LRR Technique". Using this technique, the first crystal structures of three TLR family proteins could be determined. In this review, design principles and application of the technique to protein crystallization will be summarized. For crystallization of TLRs, hagfish VLR receptors were chosen as the fusion partners and the TLR and the VLR fragments were fused at the conserved LxxLxLxxN motif to minimize local structural incompatibility. TLR-VLR hybridization did not disturb structures and functions of the target TLR proteins. The Hybrid LRR Technique is a general technique that can be applied to structural studies of other LRR proteins. It may also have broader application in biochemical and medical application of LRR proteins by modifying them without compromising their structural integrity.

  10. Vapor Pressure Determination of VM Using the Denunder-Liquid Chromatography-Mass Spectrometry Technique

    DTIC Science & Technology

    2015-01-01

    2012 – Sep 2012 4. TITLE AND SUBTITLE Vapor Pressure Determination of VM Using the Denuder– Liquid Chromatography–Mass Spectrometry Technique 5a... Liquid chromatography–mass spectrometry (LC–MS) Vapor pressure 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT UU 18. NUMBER OF...9 1 VAPOR PRESSURE DETERMINATION OF VM USING THE DENUDER– LIQUID CHROMATOGRAPHY–MASS SPECTROMETRY

  11. Radiomics: a new application from established techniques.

    PubMed

    Parekh, Vishwa; Jacobs, Michael A

    2016-01-01

    The increasing use of biomarkers in cancer have led to the concept of personalized medicine for patients. Personalized medicine provides better diagnosis and treatment options available to clinicians. Radiological imaging techniques provide an opportunity to deliver unique data on different types of tissue. However, obtaining useful information from all radiological data is challenging in the era of "big data". Recent advances in computational power and the use of genomics have generated a new area of research termed Radiomics. Radiomics is defined as the high throughput extraction of quantitative imaging features or texture (radiomics) from imaging to decode tissue pathology and creating a high dimensional data set for feature extraction. Radiomic features provide information about the gray-scale patterns, inter-pixel relationships. In addition, shape and spectral properties can be extracted within the same regions of interest on radiological images. Moreover, these features can be further used to develop computational models using advanced machine learning algorithms that may serve as a tool for personalized diagnosis and treatment guidance.

  12. Radiomics: a new application from established techniques

    PubMed Central

    Parekh, Vishwa; Jacobs, Michael A.

    2016-01-01

    The increasing use of biomarkers in cancer have led to the concept of personalized medicine for patients. Personalized medicine provides better diagnosis and treatment options available to clinicians. Radiological imaging techniques provide an opportunity to deliver unique data on different types of tissue. However, obtaining useful information from all radiological data is challenging in the era of “big data”. Recent advances in computational power and the use of genomics have generated a new area of research termed Radiomics. Radiomics is defined as the high throughput extraction of quantitative imaging features or texture (radiomics) from imaging to decode tissue pathology and creating a high dimensional data set for feature extraction. Radiomic features provide information about the gray-scale patterns, inter-pixel relationships. In addition, shape and spectral properties can be extracted within the same regions of interest on radiological images. Moreover, these features can be further used to develop computational models using advanced machine learning algorithms that may serve as a tool for personalized diagnosis and treatment guidance. PMID:28042608

  13. Diffusion weighted imaging: Technique and applications

    PubMed Central

    Baliyan, Vinit; Das, Chandan J; Sharma, Raju; Gupta, Arun Kumar

    2016-01-01

    Diffusion weighted imaging (DWI) is a method of signal contrast generation based on the differences in Brownian motion. DWI is a method to evaluate the molecular function and micro-architecture of the human body. DWI signal contrast can be quantified by apparent diffusion coefficient maps and it acts as a tool for treatment response evaluation and assessment of disease progression. Ability to detect and quantify the anisotropy of diffusion leads to a new paradigm called diffusion tensor imaging (DTI). DTI is a tool for assessment of the organs with highly organised fibre structure. DWI forms an integral part of modern state-of-art magnetic resonance imaging and is indispensable in neuroimaging and oncology. DWI is a field that has been undergoing rapid technical evolution and its applications are increasing every day. This review article provides insights in to the evolution of DWI as a new imaging paradigm and provides a summary of current role of DWI in various disease processes. PMID:27721941

  14. One-step Multiple Component Isolation from the Oil of Crinitaria tatarica (Less.) Sojak by Preparative Capillary Gas Chromatography with Characterization by Spectroscopic and Spectrometric Techniques and Evaluation of Biological Activity

    DTIC Science & Technology

    2012-01-01

    20] Adams, R. P., Identification of Essential Oil Components by Gas Chromatography /Mass Spectrometry, Allured Publishing Corporation, Carol Stream... chromatography with characterization by spectroscopic and spectrometric techniques and evaluation of biological activity Gas chromatographic analysis revealed...step multiple fractionation of the oil and separation of two unknown constituents were performed using preparative capillary gas chromatography

  15. Instrumentation: Ion Chromatography.

    ERIC Educational Resources Information Center

    Fritz, James S.

    1987-01-01

    Discusses the importance of ion chromatography in separating and measuring anions. The principles of ion exchange are presented, along with some applications of ion chromatography in industry. Ion chromatography systems are described, as well as ion pair and ion exclusion chromatography, column packings, detectors, and programming. (TW)

  16. Instrumentation: Ion Chromatography.

    ERIC Educational Resources Information Center

    Fritz, James S.

    1987-01-01

    Discusses the importance of ion chromatography in separating and measuring anions. The principles of ion exchange are presented, along with some applications of ion chromatography in industry. Ion chromatography systems are described, as well as ion pair and ion exclusion chromatography, column packings, detectors, and programming. (TW)

  17. Techniques in Experimental Mechanics Applicable to Forest Products Research

    Treesearch

    Leslie H. Groom; Audrey G. Zink

    1994-01-01

    The title of this publication-Techniques in Experimental Mechanics Applicable to Forest Products Research-is the theme of this plenary session from the 1994 Annual Meeting of the Forest Products Society (FPS). Although this session focused on experimental techniques that can be of assistance to researchers in the field of forest products, it is hoped that the...

  18. [Application of molecular biological techniques in Taenia identification].

    PubMed

    Li, Yan; Liu, Hang; Yang, Yi-Mei

    2011-10-01

    The traditional identification of Taenia spp. based on morphological features of adult and cysticercus has difficulties in identifying the morphologically similar species. The recent development of molecular techniques provides more scientific ways for distinguishing Taenia species. This paper summarizes the application of molecular biological techniques in the identification of Taenia, such as analysis of DNA sequence, PCR-RFLP and LAMP.

  19. Classroom Management Through the Application of Behavior Modification Techniques.

    ERIC Educational Resources Information Center

    Ferinden, William E., Jr.

    The primary aim of this book is to bring to the grade school teacher a survey of the most recent techniques and ideas of behavior modification which are applicable to good classroom management. All of the approaches and techniques presented could be of interest to teachers working at all grade levels. Since research has shown that the systematic…

  20. Sterilization techniques for biodegradable scaffolds in tissue engineering applications

    PubMed Central

    Dai, Zheng; Ronholm, Jennifer; Tian, Yiping; Sethi, Benu; Cao, Xudong

    2016-01-01

    Biodegradable scaffolds have been extensively studied due to their wide applications in biomaterials and tissue engineering. However, infections associated with in vivo use of these scaffolds by different microbiological contaminants remain to be a significant challenge. This review focuses on different sterilization techniques including heat, chemical, irradiation, and other novel sterilization techniques for various biodegradable scaffolds. Comparisons of these techniques, including their sterilization mechanisms, post-sterilization effects, and sterilization efficiencies, are discussed. PMID:27247758

  1. Comparative study on microsampling techniques in metabolic fingerprinting studies applying gas chromatography-MS analysis.

    PubMed

    Cala, Mónica P; Meesters, Roland Jw

    2017-09-01

    Sample collection and preparation are important steps in the metabolomics workflow. Any improvement should be aimed toward making them simpler, faster and more reproducible. This paper describes the evaluation of different types of whole blood microsampling techniques applied in a metabolic fingerprinting study of breast cancer patients. A total of 139, 124 and 128 metabolites were identified in protein precipitation, dried matrix on paper discs and Mitra(®) volumetric absorptive microsampling, respectively in 80% of the sample sets, where the quality control samples had a relative standard deviation of <30%. Ten metabolites in breast cancer samples were detected as being altered significantly (p < 0.05). Our results suggest that whole blood microsampling techniques do not obtain statistically different results in comparison with the metabolomics applied standard reference method of protein precipitation, in terms of the number of detected compounds, the reproducibility and modeling of differences between the groups.

  2. Core-shell particles: preparation, fundamentals and applications in high performance liquid chromatography.

    PubMed

    Hayes, Richard; Ahmed, Adham; Edge, Tony; Zhang, Haifei

    2014-08-29

    The challenges in HPLC are fast and efficient separation for a wide range of samples. Fast separation often results in very high operating pressure, which places a huge burden on HPLC instrumentation. In recent years, core-shell silica microspheres (with a solid core and a porous shell, also known as fused-core or superficially porous microspheres) have been widely investigated and used for highly efficient and fast separation with reasonably low pressure for separation of small molecules, large molecules and complex samples. In this review, we firstly show the types of core-shell particles and how they are generally prepared, focusing on the methods used to produce core-shell silica particles for chromatographic applications. The fundamentals are discussed on why core-shell particles can perform better with low back pressure, in terms of van Deemter equation and kinetic plots. The core-shell particles are compared with totally porous silica particles and also monolithic columns. The use of columns packed with core-shell particles in different types of liquid chromatography is then discussed, followed by illustrating example applications of such columns for separation of various types of samples. The review is completed with conclusion and a brief perspective on future development of core-shell particles in chromatography.

  3. Topics in Chemical Instrumentation: An Introduction to Supercritical Fluid Chromatography--Part 2. Applications and Future Trends.

    ERIC Educational Resources Information Center

    Palmieri, Margo D.

    1989-01-01

    Discussed are selected application and future trends in supercritical fluid chromatography (SFC). The greatest application for SFC involves those analytes that are difficult to separate using GC or LC methods. Optimum conditions for SFC are examined. Provided are several example chromatograms. (MVL)

  4. Topics in Chemical Instrumentation: An Introduction to Supercritical Fluid Chromatography--Part 2. Applications and Future Trends.

    ERIC Educational Resources Information Center

    Palmieri, Margo D.

    1989-01-01

    Discussed are selected application and future trends in supercritical fluid chromatography (SFC). The greatest application for SFC involves those analytes that are difficult to separate using GC or LC methods. Optimum conditions for SFC are examined. Provided are several example chromatograms. (MVL)

  5. Application of mass spectrometry-based proteomics techniques for the detection of protein doping in sports.

    PubMed

    Kay, Richard G; Creaser, Colin S

    2010-04-01

    Mass spectrometry-based proteomic approaches have been used to develop methodologies capable of detecting the abuse of protein therapeutics such as recombinant human erythropoietin and recombinant human growth hormone. Existing detection methods use antibody-based approaches that, although effective, suffer from long assay development times and specificity issues. The application of liquid chromatography with tandem mass spectrometry and selected reaction-monitoring-based analysis has demonstrated the ability to detect and quantify existing protein therapeutics in plasma. Furthermore, the multiplexing capability of selected reaction-monitoring analysis has also aided in the detection of multiple downstream biomarkers in a single analysis, requiring less sample than existing immunological techniques. The flexibility of mass spectrometric instrumentation has shown that the technique is capable of detecting the abuse of novel and existing protein therapeutics, and has a vital role in the fight to keep sports drug-free.

  6. Validation of a new liquid chromatography- tandem mass spectrometry ion-trap technique for the simultaneous determination of thirteen anticoagulant rodenticides, drugs, or natural products.

    PubMed

    Fourel, Isabelle; Hugnet, Christophe; Goy-Thollot, Isabelle; Berny, Philippe

    2010-03-01

    The purpose of this study was to develop and validate a liquid chromatography-tandem mass spectrometry method for the identification and quantification of anticoagulant (anti-vitamin K or AVK) compounds, including rodenticides, drugs, and natural products because no published method could be found. The proposed method is based on ion-trap technology with electrospray ionization (ESI) and multiple reaction monitoring (MRM) technique. Each AVK is identified by means of its retention time, precursor ion, and two product ions. Plasma samples are extracted by liquid-liquid partition on Toxi-tube B((R)). The method was validated on dog plasma and gave good results in terms of specificity, linearity, and percent recovery for the 14 AVK tested (warfarin, acenocoumarol, bromadiolone, brodifacoum, chlorophacinone, coumatetralyl, dicoumarol, difenacoum, difethialone, flocoumafen, fluindione, phenindione, and tioclomarol). The limits of detection ranged from 5 to 25 ng/mL. Intraday repeatability was good, but interday repeatability was more variable though still sufficient for our diagnostic purposes. The technique was successfully applied in a series of clinical investigations to demonstrate its applicability in various animal species and gave very high sensitivity and specificity results.

  7. 48 CFR 9904.420-50 - Techniques for application.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.420-50 Techniques for application. (a) The IR&D and B&P... or applicable Cost Accounting Standards for allocation of indirect costs. (b) The IR&D and B&P cost pools for a segment consist of the project costs plus allocable home office IR&D and B&P costs. (c)...

  8. 48 CFR 9904.420-50 - Techniques for application.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.420-50 Techniques for application. (a) The IR&D and B&P... or applicable Cost Accounting Standards for allocation of indirect costs. (b) The IR&D and B&P cost pools for a segment consist of the project costs plus allocable home office IR&D and B&P costs. (c)...

  9. 48 CFR 9904.420-50 - Techniques for application.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.420-50 Techniques for application. (a) The IR&D and B&P... or applicable Cost Accounting Standards for allocation of indirect costs. (b) The IR&D and B&P cost pools for a segment consist of the project costs plus allocable home office IR&D and B&P costs. (c)...

  10. The Application of Nuclear Techniques to Solid State Devices.

    DTIC Science & Technology

    1980-12-15

    35) as the same technique showed. We then applied the method to clarify the atomic transport in bimetal layer silicide reactions. In these experiments...UNCLASSIFIED NL ’ LEVEWL L* . 4’ -.-- C7..:i I) FINAL TECHNICAL REPORT submitted to --- v OFFICE OF NAVAL RESEARCH on THE APPLICATION OF NUCLEAR TECHNIQUES TO...December 15, 1980,. , ...- 1’J I. Introduction The program "The Application of Nuclear Techniques to Solid State Devices" began on 1 January 1975. It was

  11. Application of molecular techniques on heterotrophic hydrogen production research.

    PubMed

    Li, R Y; Zhang, T; Fang, H H P

    2011-09-01

    This paper reviews the application of molecular techniques in heterotrophic hydrogen production studies. Commonly used molecular techniques are introduced briefly first, including cloning-sequencing after polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE), terminal-restriction fragment length polymorphism (T-RFLP), fluorescence in situ hybridization (FISH) and quantitative real-time PCR. Application of the molecular techniques in heterotrophic hydrogen production studies are discussed in details, focusing on identification of new isolates for hydrogen production, characterization of microbial compositions in bioreactors, monitoring microbial diversity variation, visualization of microbial distribution in hydrogen-producing granular sludge, and quantification of various microbial populations. Some significant findings in recent hydrogen production studies with the application of molecular techniques are discussed, followed by a research outlook of the heterotrophic biohydrogen field.

  12. Analysis of trihalomethanes in drinking water using headspace-SPME technique with gas chromatography.

    PubMed

    Cho, Deok-Hee; Kong, Sung-Ho; Oh, Seong-Geun

    2003-01-01

    In many drinking water treatment plants, the chlorination process is one of the main techniques used for the disinfection of water. This disinfecting treatment leads to the formation of trihalomethanes (THMs) such as chloroform, dichlorobromomethane, chlorodibromomethane and bromoform. In this study, headspace-solid-phase microextraction (HS-SPME, 85 microm carboxen/polydimethylsiloxane fiber) technique was applied for the analysis of THMs in drinking water. The effects of experimental parameters such as kinds of SPME fiber, the volume ratio of sample to headspace, the addition of salts, magnetic stirring, extraction temperature, extraction time and desorption time on the analysis were investigated. Analytical parameters such as linearity, repeatability and limit of detection were also evaluated. The results of THMs from the survey of Seongnam (Korea) drinking water samples showed that the highest total trihalomethane and chloroform were 24.03 and 13.34 microg/l, which were well within the Korean drinking water quality standard of 100 and 80 microg/l, respectively.

  13. Millimeter-wave/THz FMCW radar techniques for sensing applications

    NASA Astrophysics Data System (ADS)

    Mirando, D. Amal; Higgins, Michael D.; Wang, Fenggui; Petkie, Douglas T.

    2016-10-01

    Millimeter-wave and terahertz continuous-wave radar systems have been used to measure physiological signatures for biometric applications and for a variety of non-destructive evaluation applications, such as the detection of defects in materials. Sensing strategies for the simplest homodyne systems, such as a Michelson Interferometer, can be enhanced by using Frequency Modulated Continuous Wave (FMCW) techniques. This allows multiple objects or surfaces to be range resolved while monitoring the phase of the signal in a particular range bin. We will discuss the latest developments in several studies aimed at demonstrating how FMCW techniques can enhance mmW/THz sensing applications.

  14. Exploring the possibilities of cryogenic cooling in liquid chromatography for biological applications: a proof of principle.

    PubMed

    Eghbali, Hamed; Sandra, Koen; Tienpont, Bart; Eeltink, Sebastiaan; Sandra, Pat; Desmet, Gert

    2012-02-21

    The possibilities to use cryogenic cooling to trap components in liquid chromatography was investigated. In a first step, van 't Hoff plots were measured with a reversed-phase column using the temperature control unit of a conventional high performance liquid chromatography (HPLC) system to gain insight in the retention behavior of proteins at low temperatures. It was estimated that retention factors in the range of k = 10(4) could be achieved at T = -20 °C for lysozyme, indicating that temperature is a usable parameter to trap components in LC. In a next step, trapping experiments were carried out on a nano-LC system, equipped with a UV-detector, using a commercial reversed-phase column. An in-house built setup, allowing cooling of a segment of the column down to temperatures below T = -20 °C, was used to trap components. Experiments were conducted under isocratic and gradient conditions with methanol as organic solvent. It is demonstrated that, by thermally trapping and elution of components, an enhanced S/N ratio and decreased peak widths can be obtained. At the same time, a significant increase in pressure drop occurs during the cooling process. Limitations and benefits of the technique are further discussed.

  15. Chemometrics applications in biotechnology processes: predicting column integrity and impurity clearance during reuse of chromatography resin.

    PubMed

    Rathore, Anurag S; Mittal, Shachi; Lute, Scott; Brorson, Kurt

    2012-01-01

    Separation media, in particular chromatography media, is typically one of the major contributors to the cost of goods for production of a biotechnology therapeutic. To be cost-effective, it is industry practice that media be reused over several cycles before being discarded. The traditional approach for estimating the number of cycles a particular media can be reused for involves performing laboratory scale experiments that monitor column performance and carryover. This dataset is then used to predict the number of cycles the media can be used at manufacturing scale (concurrent validation). Although, well accepted and widely practiced, there are challenges associated with extrapolating the laboratory scale data to manufacturing scale due to differences that may exist across scales. Factors that may be different include: level of impurities in the feed material, lot to lot variability in feedstock impurities, design of the column housing unit with respect to cleanability, and homogeneity of the column packing. In view of these challenges, there is a need for approaches that may be able to predict column underperformance at the manufacturing scale over the product lifecycle. In case such an underperformance is predicted, the operators can unpack and repack the chromatography column beforehand and thus avoid batch loss. Chemometrics offers one such solution. In this article, we present an application of chemometrics toward the analysis of a set of chromatography profiles with the intention of predicting the various events of column underperformance including the backpressure buildup and inefficient deoxyribonucleic acid clearance. Copyright © 2012 American Institute of Chemical Engineers (AIChE).

  16. High-performance liquid chromatography as a technique to determine protein adsorption onto hydrophilic/hydrophobic surfaces.

    PubMed

    Huang, Tongtong; Anselme, Karine; Sarrailh, Segolene; Ponche, Arnaud

    2016-01-30

    The purpose of this study is to evaluate the potential of simple high performance liquid chromatography (HPLC) setup for quantification of adsorbed proteins on various type of plane substrates with limited area (<3 cm(2)). Protein quantification was investigated with a liquid chromatography chain equipped with a size exclusion column or a reversed-phase column. By evaluating the validation of the method according to guidelines of the International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH), all the results obtained by HPLC were reliable. By simple adsorption test at the contact of hydrophilic (glass) and hydrophobic (polydimethylsiloxane: PDMS) surfaces, kinetics of adsorption were determined and amounts of adsorbed bovine serum albumin, myoglobin and lysozyme were obtained: as expected for each protein, the amount adsorbed at the plateau on glass (between 0.15 μg/cm(2) and 0.4 μg/cm(2)) is lower than for hydrophobic PDMS surfaces (between 0.45 μg/cm(2) and 0.8 μg/cm(2)). These results were consistent with bicinchoninic acid protein determination. According to ICH guidelines, both Reversed Phase and Size Exclusion HPLC can be validated for quantification of adsorbed protein. However, we consider the size exclusion approach more interesting in this field because additional informations can be obtained for aggregative proteins. Indeed, monomer, dimer and oligomer of bovine serum albumin (BSA) were observed in the chromatogram. On increasing the temperature, we found a decrease of peak intensity of bovine serum albumin as well as the fraction of dimer and oligomer after contact with PDMS and glass surface. As the surface can act as a denaturation parameter, these informations can have a huge impact on the elucidation of the interfacial behavior of protein and in particular for aggregation processes in pharmaceutical applications.

  17. Principles and clinical applications of liquid chromatography - tandem mass spectrometry for the determination of adrenal and gonadal steroid hormones.

    PubMed

    Kulle, A E; Welzel, M; Holterhus, P-M; Riepe, F G

    2011-10-01

    Liquid-chromatography - tandem mass spectrometry (LC-MS/MS) is becoming the method of choice for clinical steroid analysis. In most instances, it has the advantage of higher sensitivity, better reproducibility and greater specificity than commercial immunoassay techniques. The method requires only minimal sample preparation and a small sample volume. Furthermore, it has the potential to analyze multiple steroids simultaneously. Modern instruments guarantee high throughput, allowing an affordable price for the individual assay. All this makes LC-MS/MS an attractive method for use in a clinical setting. Reliable reference ranges for the detected analytes are the pre-requisite for their clinical use. If these are available, LC-MS/MS can find application in congenital disorders of steroid metabolism, such as congenital adrenal hyperplasia, disorders of sex development and disorders of salt homeostasis, as well as in acquired disorders of steroid metabolism, such as primary aldosteronism, Cushing's disease, Addison's disease, and hyperandrogenemia, as well as in psychiatric disease states such as depression or anxiety disorders. The principles of LC-MS/MS for steroid measurement, the pros and cons of LC-MS/MS compared with conventional immunoassays and the possible applications in clinical routine, with a special focus on pediatric endocrinology needs, are discussed here.

  18. Aspects of matrix effects in applications of liquid chromatography-mass spectrometry to forensic and clinical toxicology--a review.

    PubMed

    Peters, Frank T; Remane, Daniela

    2012-06-01

    In the last decade, liquid chromatography coupled to (tandem) mass spectrometry (LC-MS(-MS)) has become a versatile technique with many routine applications in clinical and forensic toxicology. However, it is well-known that ionization in LC-MS(-MS) is prone to so-called matrix effects, i.e., alteration in response due to the presence of co-eluting compounds that may increase (ion enhancement) or reduce (ion suppression) ionization of the analyte. Since the first reports on such matrix effects, numerous papers have been published on this matter and the subject has been reviewed several times. However, none of the existing reviews has specifically addressed aspects of matrix effects of particular interest and relevance to clinical and forensic toxicology, for example matrix effects in methods for multi-analyte or systematic toxicological analysis or matrix effects in (alternative) matrices almost exclusively analyzed in clinical and forensic toxicology, for example meconium, hair, oral fluid, or decomposed samples in postmortem toxicology. This review article will therefore focus on these issues, critically discussing experiments and results of matrix effects in LC-MS(-MS) applications in clinical and forensic toxicology. Moreover, it provides guidance on performance of studies on matrix effects in LC-MS(-MS) procedures in systematic toxicological analysis and postmortem toxicology.

  19. Levels of phytosterol oxides in enriched and nonenriched spreads: application of a thin-layer chromatography-gas chromatography methodology.

    PubMed

    Conchillo, Ana; Cercaci, Luisito; Ansorena, Diana; Rodriguez-Estrada, Maria Teresa; Lercker, Giovanni; Astiasarán, Iciar

    2005-10-05

    The content of phytosterol oxidation products (POPs) in enriched and nonenriched commercial spreads was evaluated by thin-layer chromatography-gas chromatography (TLC-GC). Oxides of beta-sitosterol, campesterol, and stigmasterol were produced by thermo-oxidation (7-hydroxy, 7-keto, and epoxy derivatives) and chemical synthesis (triol derivatives), which were then separated and identified by TLC-GC. Their identification was further confirmed by GC-mass spectrometry (GC-MS). The total amounts of phytosterols found were 6.07 and 0.33 g/100 g of sample in phytosterol-enriched and nonenriched spread, respectively, whereas the total POPs contents were 45.60 and 13.31 mg/kg of sample in the enriched and nonenriched products. The main POPs found were the 7-keto derivatives of all phytosterols analyzed; 7-ketositosterol was the most abundant one (14.96 and 5.93 mg/kg of sample in phytosterol-enriched and nonenriched spread). No beta-epoxy and triol derivatives were detected in both types of samples. The enriched spread presented a lower phytosterol oxidation rate (0.07%) than the nonenriched one (0.41%).

  20. Application of the tissue transfer technique in veterinary cytopathology.

    PubMed

    Stone, Brett M; Gan, David

    2014-06-01

    Limited availability of diagnostic cytopathologic material may preclude additional diagnostic techniques. Tissue transfer allows for preparation of additional slides from a single original slide. Information pertaining to the application of the tissue transfer technique in veterinary cytopathology is lacking. The objectives were to evaluate the application of the tissue transfer technique on Quick Dip-stained veterinary cytologic smears and to assess if a selection of histochemical and immunocytochemical stains, and PCR analyses could be performed on transferred material. Archived Quick Dip-stained canine lymph node aspirate smears from previously diagnosed lymphoma cases were utilized to validate and optimize the tissue transfer technique. In this technique, diagnostic material is lifted from the original stained slide, is divided and transferred to multiple new slides. Histochemical stains such as Gram, periodic acid Schiff, Congo red, and Ziehl-Neelson, immunohistochemistry for CD3 and PAX5, and PCR for cryptococcal and mycobacterial organisms were selectively performed on transferred material. The tissue transfer technique was simple, and transferred Quick Dip-stained material retained cellular morphology. Histochemical and immunohistochemical stains, and PCR analysis yielded reliable results when performed on the additional smears produced by this technique. The tissue transfer technique was simple and easy to perform on previously Quick Dip-stained cytology smears. Cellular detail was preserved and multiple additional ancillary diagnostic techniques were facilitated, such as histochemical and immunohistochemical stains, and PCR analysis. © 2014 American Society for Veterinary Clinical Pathology and European Society for Veterinary Clinical Pathology.

  1. Recent trends in electrospinning of polymer nanofibers and their applications in ultra thin layer chromatography.

    PubMed

    Moheman, Abdul; Alam, Mohammad Sarwar; Mohammad, Ali

    2016-03-01

    Fabrication of polymer derived electrospun nanofibers by electrospinning as chromatographic sorbent bed for ultra-thin layer chromatography (UTLC) is a very demanding topic in analytical chemistry. This review presents an overview of recent development in the fabrication of polymer derived electrospun nanofibers and their applications to design UTLC plates as stationary phases for on-plate identification and separation of analytes from their mixture solutions. It has been reported that electrospun fiber based stationary phases in UTLC have enhanced separation efficiency to provide separation of analyte mixture in a shorter development time than those of traditional particle-based TLC stationary phases. In addition, electrospun UTLC is cost effective and can be modified for obtaining different surface selectivities by changing the polymer materials to electrospun devices. Electrospun UTLC plates are not available commercially till date and efforts are being rendered for their commercialization. The morphology and diameter of electrospun nanofibers are highly dependent on several parameters such as type of polymer, polymer molecular weight, solvent, viscosity, conductivity, surface tension, applied voltage, collector distance and flow rate of the polymer solution during electrospinning process. Among the aforementioned parameters, solution viscosity is an important parameter which is mainly influenced by polymer concentration. This review provides evidence for the fabrication of UTLC plates containing electrospun polymer nanofibers. Furthermore, the future prospects related to electrospinning and its application in obtaining of different types of electrospun nanofibers are discussed. The present communication is aimed to review the work which appeared during 2009-2014 on the application of polymer derived electrospun nanofibers in ultra thin layer chromatography. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Current Applications of Liquid Chromatography/Mass Spectrometry in Pharmaceutical Discovery After a Decade of Innovation

    NASA Astrophysics Data System (ADS)

    Ackermann, Bradley L.; Berna, Michael J.; Eckstein, James A.; Ott, Lee W.; Chaudhary, Ajai K.

    2008-07-01

    Current drug discovery involves a highly iterative process pertaining to three core disciplines: biology, chemistry, and drug disposition. For most pharmaceutical companies the path to a drug candidate comprises similar stages: target identification, biological screening, lead generation, lead optimization, and candidate selection. Over the past decade, the overall efficiency of drug discovery has been greatly improved by a single instrumental technique, liquid chromatography/mass spectrometry (LC/MS). Transformed by the commercial introduction of the atmospheric pressure ionization interface in the mid-1990s, LC/MS has expanded into almost every area of drug discovery. In many cases, drug discovery workflow has been changed owing to vastly improved efficiency. This review examines recent trends for these three core disciplines and presents seminal examples where LC/MS has altered the current approach to drug discovery.

  3. [Optimisation of a high-efficiency liquid chromatography technique for measuring lamotrigine in human plasma].

    PubMed

    Rivas, N; Zarzuelo, A; López, F G

    2010-01-01

    The purpose of this study was to optimise the HPLC-UV bio-analytical method currently used by the Salamanca University Clinical Hospital for determining lamotrigine plasma levels. The developed HPLC-UV analytic technique currently in use was shown to be linear, exact and precise, and suitable for use in routine monitoring of lamotrigine levels. The drawback of this method has always been the time required for analysing samples, so our aim was to improve on that elapsed time. That improvement involved using a different chromatographic column from the one used up until now. We replaced the column that was normally used (Kromasil-100C18-5 microm-15*0.4 cm with a LiChroCART-RP18e-3 microm-5.5*0.4 cm); in both cases, a liquid-liquid extraction was performed and the same sample extraction protocol was followed. Both validation methods showed that the two column types are valid for routine lamotrigine monitoring. The decrease in retention time, in addition to a lower quantification limit and better precision and accuracy parameters obtained with the LiChorCART column, suggest that this unit is ideal for use in clinical practice because it enables a large number of determinations to be performed in less time and the greater precision of LTG measurements. Copyright © 2009 SEFH. Published by Elsevier Espana. All rights reserved.

  4. Applications of monolithic solid-phase extraction in chromatography-based clinical chemistry assays.

    PubMed

    Bunch, Dustin R; Wang, Sihe

    2013-04-01

    Complex matrices, for example urine, serum, plasma, and whole blood, which are common in clinical chemistry testing, contain many non-analyte compounds that can interfere with either detection or in-source ionization in chromatography-based assays. To overcome this problem, analytes are extracted by protein precipitation, solid-phase extraction (SPE), and liquid-liquid extraction. With correct chemistry and well controlled material SPE may furnish clean specimens with consistent performance. Traditionally, SPE has been performed with particle-based adsorbents, but monolithic SPE is attracting increasing interest of clinical laboratories. Monoliths, solid pieces of stationary phase, have bimodal structures consisting of macropores, which enable passage of solvent, and mesopores, in which analytes are separated. This structure results in low back-pressure with separation capabilities similar to those of particle-based adsorbents. Monoliths also enable increased sample throughput, reduced solvent use, varied support formats, and/or automation. However, many of these monoliths are not commercially available. In this review, application of monoliths to purification of samples from humans before chromatography-based assays will be critically reviewed.

  5. Preparation and characterization of alkyl methacrylate-based monolithic columns for capillary gas chromatography applications.

    PubMed

    Yusuf, Kareem; Aqel, Ahmad; A L Othman, Zeid; Badjah-Hadj-Ahmed, Ahmed Yacine

    2013-08-02

    Gas chromatography (GC) is considered the least common application of both polymer and silica-based monolithic columns. This study describes the fabrication of alkyl methacrylate monolithic materials for use as stationary phases in capillary gas chromatography. Following the deactivation of the capillary surface with 3-(trimethoxysilyl)propyl methacrylate (TMSM), the monoliths were formed by the co-polymerization of either hexyl methacrylate (HMA) or lauryl methacrylate (LMA) with different percentage of ethylene glycol dimethacrylate (EDMA) in presence of an initiator (azobisisobutyronitrile, AIBN) and a mixture of porogens include 1-propanol, 1,4-butanediol and water. The monoliths were prepared in 500mm length capillaries possessing inner diameters of 250μm. The efficiencies of the monolithic columns for low molecular weight compounds significantly improved as the percentage of crosslinker was increased, because of the greater proportion of pores less than 50nm. The columns containing lower percentages of crosslinker were able to rapidly separate a series of 8 alkane members in 0.7min, but the separation was less efficient for the light alkanes. Columns prepared with the lauryl methacrylate monomer yielded a different morphology for the monolith-interconnected channels. The channels were more branched, which increased the separation time, and unlike the other columns, allowed for temperature programming.

  6. A novel Fast Gas Chromatography based technique for higher time resolution measurements of speciated monoterpenes in air

    NASA Astrophysics Data System (ADS)

    Jones, C. E.; Kato, S.; Nakashima, Y.; Kajii, Y.

    2013-12-01

    Biogenic emissions supply the largest fraction of non-methane volatile organic compounds (VOC) from the biosphere to the atmospheric boundary layer, and typically comprise a complex mixture of reactive terpenes. Due to this chemical complexity, achieving comprehensive measurements of biogenic VOC (BVOC) in air within a satisfactory time resolution is analytically challenging. To address this, we have developed a novel, fully automated Fast Gas Chromatography (Fast-GC) based technique to provide higher time resolution monitoring of monoterpenes (and selected other C9-C15 terpenes) during plant emission studies and in ambient air. To our knowledge, this is the first study to apply a Fast-GC based separation technique to achieve quantification of terpenes in air. Three chromatography methods have been developed for atmospheric terpene analysis under different sampling scenarios. Each method facilitates chromatographic separation of selected BVOC within a significantly reduced analysis time compared to conventional GC methods, whilst maintaining the ability to quantify individual monoterpene structural isomers. Using this approach, the C10-C15 BVOC composition of single plant emissions may be characterised within a ~ 14 min analysis time. Moreover, in situ quantification of 12 monoterpenes in unpolluted ambient air may be achieved within an ~ 11 min chromatographic separation time (increasing to ~ 19 min when simultaneous quantification of multiple oxygenated C9-C10 terpenoids is required, and/or when concentrations of anthropogenic VOC are significant). This corresponds to a two- to fivefold increase in measurement frequency compared to conventional GC methods. Here we outline the technical details and analytical capability of this chromatographic approach, and present the first in situ Fast-GC observations of 6 monoterpenes and the oxygenated BVOC linalool in ambient air. During this field deployment within a suburban forest ~ 30 km west of central Tokyo, Japan, the

  7. Bioanalytical Applications of Fluorescence Line-Narrowing and Non-Line-Narrowing Spectroscopy Interfaced with Capillary Electrophoresis and High-Performance Liquid Chromatography

    SciTech Connect

    Roberts, Kenneth Paul

    2001-01-01

    Capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) are widely used analytical separation techniques with many applications in chemical, biochemical, and biomedical sciences. Conventional analyte identification in these techniques is based on retention/migration times of standards; requiring a high degree of reproducibility, availability of reliable standards, and absence of coelution. From this, several new information-rich detection methods (also known as hyphenated techniques) are being explored that would be capable of providing unambiguous on-line identification of separating analytes in CE and HPLC. As further discussed, a number of such on-line detection methods have shown considerable success, including Raman, nuclear magnetic resonance (NMR), mass spectrometry (MS), and fluorescence line-narrowing spectroscopy (FLNS). In this thesis, the feasibility and potential of combining the highly sensitive and selective laser-based detection method of FLNS with analytical separation techniques are discussed and presented. A summary of previously demonstrated FLNS detection interfaced with chromatography and electrophoresis is given, and recent results from on-line FLNS detection in CE (CE-FLNS), and the new combination of HPLC-FLNS, are shown.

  8. Videogrammetric Model Deformation Measurement Technique for Wind Tunnel Applications

    NASA Technical Reports Server (NTRS)

    Barrows, Danny A.

    2006-01-01

    Videogrammetric measurement technique developments at NASA Langley were driven largely by the need to quantify model deformation at the National Transonic Facility (NTF). This paper summarizes recent wind tunnel applications and issues at the NTF and other NASA Langley facilities including the Transonic Dynamics Tunnel, 31-Inch Mach 10 Tunnel, 8-Ft high Temperature Tunnel, and the 20-Ft Vertical Spin Tunnel. In addition, several adaptations of wind tunnel techniques to non-wind tunnel applications are summarized. These applications include wing deformation measurements on vehicles in flight, determining aerodynamic loads based on optical elastic deformation measurements, measurements on ultra-lightweight and inflatable space structures, and the use of an object-to-image plane scaling technique to support NASA s Space Exploration program.

  9. High-Performance Liquid Chromatography-Mass Spectrometry.

    ERIC Educational Resources Information Center

    Vestal, Marvin L.

    1984-01-01

    Reviews techniques for online coupling of high-performance liquid chromatography with mass spectrometry, emphasizing those suitable for application to nonvolatile samples. Also summarizes the present status, strengths, and weaknesses of various techniques and discusses potential applications of recently developed techniques for combined liquid…

  10. Crystallization techniques in wastewater treatment: An overview of applications.

    PubMed

    Lu, Haijiao; Wang, Jingkang; Wang, Ting; Wang, Na; Bao, Ying; Hao, Hongxun

    2017-04-01

    As a by-product of industrial or domestic activities, wastewater of different compositions has caused serious environmental problems all over the world. Facing the challenge of wastewater treatment, researchers have begun to make use of crystallization techniques in wastewater treatment. Crystallization techniques have many advantages, such as high efficiency, energy saving, low costs, less space occupation and so on. In recent decades, crystallization is considered as one of promising techniques for wastewater treatment, especially for desalination, water and salt recovery. It has been widely used in engineering applications all over the world. In this paper, various crystallization techniques in wastewater treatment are summarized, mainly including evaporation crystallization, cooling crystallization, reaction crystallization, drowning-out crystallization and membrane distillation crystallization. Overall, they are mainly used for desalination, water and salt recovery. Their applications, advantages and disadvantages were compared and discussed in detail. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Determination of the triacylglycerol fraction in fish oil by comprehensive liquid chromatography techniques with the support of gas chromatography and mass spectrometry data.

    PubMed

    Beccaria, Marco; Costa, Rosaria; Sullini, Giuseppe; Grasso, Elisa; Cacciola, Francesco; Dugo, Paola; Mondello, Luigi

    2015-07-01

    Fish oil made from menhaden (Brevoortia tyrannus) can be used as a dietary supplement for the presence of high levels of the long-chained omega-3 fatty acids, viz. epentaenoic and docosahexanoic. In this work, for the first time, two different multidimensional approaches were developed and compared, in terms of peak capacity, for triacylglycerol characterization. In particular, silver ion chromatography with a silver-ion column and non-aqueous reverse-phase liquid chromatography with a C18 column were tested in both comprehensive (stop-flow) and off-line modes. The use of mass spectra attained by atmospheric pressure chemical ionization for both LC approaches, and the fatty acids methyl esters profile of menhaden oil obtained by gas chromatography analysis, greatly supported the elucidation of the triacylglycerol content in menhaden oil. The off-line approach afforded a better separation and, thus, higher peak capacity to allow identifying and semiquantifying more than 250 triacylglycerols. Such a huge number has never been reported for a menhaden oil sample.The main disadvantage of such an approach over the stop-flow one was the longer analysis time, mainly attributable to solvent exchange between the two dimensions.

  12. Application of Material Characterization Techniques to Electrical Forensic Analysis

    SciTech Connect

    Mills, T.D.

    2003-03-11

    The application of forensic science techniques to electrical equipment failure investigation has not been widely documented in the engineering world. This paper is intended to share an example of using material characterization techniques to support an initial cause determination of an electrical component failure event. The resulting conclusion supported the initial cause determination and ruled out the possibility of design deficiencies. Thus, the qualification testing of the equipment was allowed to continue to successful completion.

  13. Application of turbulent flow chromatography to the metabonomic analysis of human plasma: comparison with protein precipitation.

    PubMed

    Michopoulos, Filippos; Edge, Antony M; Theodoridis, Georgios; Wilson, Ian D

    2010-06-01

    The use of turbulent flow chromatography (TFC) as a method for the rapid metabonomic LC-MS analysis of plasma as an alternative to solvent-based protein precipitation has been investigated. This comparison has shown that TFC can be effectively used in this application with the benefit that off-line sample handling is significantly reduced. However, analysis of the data obtained via TFC for human plasma reveals substantial differences in the overall metabolite profiles compared with methanol-precipitated HPLC-MS. This seems in part at least to be related to greatly reduced amounts of phospholipids (ca. 10 fold reduction) for the turbulent flow methodology compared with protein-precipitated samples. The significance of these differences with respect to metabolite profiles as a result of the sample preparation method used are discussed.

  14. Chemiluminescence detection in liquid chromatography: applications to clinical, pharmaceutical, environmental and food analysis--a review.

    PubMed

    Gámiz-Gracia, Laura; García-Campaña, Ana M; Huertas-Pérez, José F; Lara, Francisco J

    2009-04-27

    Chemiluminescence (CL)-based detection has become in the last years quite a useful detecting tool in liquid chromatography (HPLC) due to its simplicity, low cost and high sensitivity and selectivity, and the development in instrumentation. Minimal instrumentation is required and no external light source is needed; thus, the optical system is quite simple. As a consequence, a wide variety of analytical methods have been developed in clinical, pharmaceutical, environmental and food analysis. In this review, applications of the HPLC-CL coupling in those different fields have been included and classified in relation to the different CL systems employed (namely peroxyoxalate reaction, tris(2,2'-bipyridine) ruthenium (II) reaction, luminol system and direct oxidations) and also sub-classified according to the group of analyte. The review covers the literature from 2000 until the end of 2008.

  15. Core-Shell Columns in High-Performance Liquid Chromatography: Food Analysis Applications.

    PubMed

    Preti, Raffaella

    2016-01-01

    The increased separation efficiency provided by the new technology of column packed with core-shell particles in high-performance liquid chromatography (HPLC) has resulted in their widespread diffusion in several analytical fields: from pharmaceutical, biological, environmental, and toxicological. The present paper presents their most recent applications in food analysis. Their use has proved to be particularly advantageous for the determination of compounds at trace levels or when a large amount of samples must be analyzed fast using reliable and solvent-saving apparatus. The literature hereby described shows how the outstanding performances provided by core-shell particles column on a traditional HPLC instruments are comparable to those obtained with a costly UHPLC instrumentation, making this novel column a promising key tool in food analysis.

  16. Light emitting diode induced chemiluminescence and its application as a detector for high performance liquid chromatography.

    PubMed

    Zhang, Xinfeng; Hu, Yiyu; Sun, Aimin; Lv, Yi; Hou, Xiandeng

    2009-12-18

    Some categories of compounds, including quinones, coumarins, flavins, and xanthene dyes, were found to produce strong chemiluminescence (CL) signals with luminol in sample solution under the irradiation of light emitting diodes (LED) with proper wavelengths. Based on this phenomenon, a compact photochemical reactor was constructed to develop a novel LED induced CL detector for high performance liquid chromatography (HPLC). The effects of related parameters including LED wavelength, luminol concentration, flow rate, pH, and eluents of HPLC were investigated in detail. Under the optimized conditions, the limits of detections (LODs) were in the range of 0.2-80 ng mL(-1). The applications and accuracy of the proposed method were validated by analyzing food samples such as milk powder, beer, candy and beverage with satisfactory results.

  17. Core-Shell Columns in High-Performance Liquid Chromatography: Food Analysis Applications

    PubMed Central

    Preti, Raffaella

    2016-01-01

    The increased separation efficiency provided by the new technology of column packed with core-shell particles in high-performance liquid chromatography (HPLC) has resulted in their widespread diffusion in several analytical fields: from pharmaceutical, biological, environmental, and toxicological. The present paper presents their most recent applications in food analysis. Their use has proved to be particularly advantageous for the determination of compounds at trace levels or when a large amount of samples must be analyzed fast using reliable and solvent-saving apparatus. The literature hereby described shows how the outstanding performances provided by core-shell particles column on a traditional HPLC instruments are comparable to those obtained with a costly UHPLC instrumentation, making this novel column a promising key tool in food analysis. PMID:27143972

  18. Review and classification of variability analysis techniques with clinical applications

    PubMed Central

    2011-01-01

    Analysis of patterns of variation of time-series, termed variability analysis, represents a rapidly evolving discipline with increasing applications in different fields of science. In medicine and in particular critical care, efforts have focussed on evaluating the clinical utility of variability. However, the growth and complexity of techniques applicable to this field have made interpretation and understanding of variability more challenging. Our objective is to provide an updated review of variability analysis techniques suitable for clinical applications. We review more than 70 variability techniques, providing for each technique a brief description of the underlying theory and assumptions, together with a summary of clinical applications. We propose a revised classification for the domains of variability techniques, which include statistical, geometric, energetic, informational, and invariant. We discuss the process of calculation, often necessitating a mathematical transform of the time-series. Our aims are to summarize a broad literature, promote a shared vocabulary that would improve the exchange of ideas, and the analyses of the results between different studies. We conclude with challenges for the evolving science of variability analysis. PMID:21985357

  19. Review and classification of variability analysis techniques with clinical applications.

    PubMed

    Bravi, Andrea; Longtin, André; Seely, Andrew J E

    2011-10-10

    Analysis of patterns of variation of time-series, termed variability analysis, represents a rapidly evolving discipline with increasing applications in different fields of science. In medicine and in particular critical care, efforts have focussed on evaluating the clinical utility of variability. However, the growth and complexity of techniques applicable to this field have made interpretation and understanding of variability more challenging. Our objective is to provide an updated review of variability analysis techniques suitable for clinical applications. We review more than 70 variability techniques, providing for each technique a brief description of the underlying theory and assumptions, together with a summary of clinical applications. We propose a revised classification for the domains of variability techniques, which include statistical, geometric, energetic, informational, and invariant. We discuss the process of calculation, often necessitating a mathematical transform of the time-series. Our aims are to summarize a broad literature, promote a shared vocabulary that would improve the exchange of ideas, and the analyses of the results between different studies. We conclude with challenges for the evolving science of variability analysis.

  20. [Cardiac computed tomography: new applications of an evolving technique].

    PubMed

    Martín, María; Corros, Cecilia; Calvo, Juan; Mesa, Alicia; García-Campos, Ana; Rodríguez, María Luisa; Barreiro, Manuel; Rozado, José; Colunga, Santiago; de la Hera, Jesús M; Morís, César; Luyando, Luis H

    2015-01-01

    During the last years we have witnessed an increasing development of imaging techniques applied in Cardiology. Among them, cardiac computed tomography is an emerging and evolving technique. With the current possibility of very low radiation studies, the applications have expanded and go further coronariography In the present article we review the technical developments of cardiac computed tomography and its new applications. Copyright © 2014 Instituto Nacional de Cardiología Ignacio Chávez. Published by Masson Doyma México S.A. All rights reserved.

  1. Edible holography: the application of holographic techniques to food processing

    NASA Astrophysics Data System (ADS)

    Begleiter, Eric

    1991-07-01

    Reports on current research efforts in the application of holographic techniques to food processing. Through a simple and inexpensive production process, diffractive and holographic effects of color, depth, and motion can be transferred to edible products. Processes are discussed which can provide a competitive advantage to the marketing of a diverse group of sugar and non-sugar-based consumable products, i.e. candies, chocolates, lollipops, snacks, cereals and pharmaceuticals. Techniques, applications, and products are investigated involving the shift from a chemical to a physical basis for the production of food coloring and decorating.

  2. Renaissance of Aliphatic Polycarbonates: New Techniques and Biomedical Applications

    PubMed Central

    Xu, Jianwen; Feng, Ellva; Song, Jie

    2014-01-01

    Aliphatic polycarbonates were discovered a long time ago, with their conventional applications mostly limited to low molecular weight oligomeric intermediates for copolymerization with other polymers. Recent developments in polymerization techniques have overcome the difficulty in preparing high molecular weight aliphatic polycarbonates. These in turn, along with new functional monomers, have enabled the preparation of a wide range of aliphatic polycarbonates with diverse chemical compositions and structures. This review summarizes the latest polymerization techniques for preparing well-defined functional aliphatic polycarbonates, as well as the new applications of those aliphatic polycarbonates, esecially in the biomedical field. PMID:24994939

  3. Lipidomics: Techniques, Applications, and Outcomes Related to Biomedical Sciences.

    PubMed

    Yang, Kui; Han, Xianlin

    2016-11-01

    Lipidomics is a newly emerged discipline that studies cellular lipids on a large scale based on analytical chemistry principles and technological tools, particularly mass spectrometry. Recently, techniques have greatly advanced and novel applications of lipidomics in the biomedical sciences have emerged. This review provides a timely update on these aspects. After briefly introducing the lipidomics discipline, we compare mass spectrometry-based techniques for analysis of lipids and summarize very recent applications of lipidomics in health and disease. Finally, we discuss the status of the field, future directions, and advantages and limitations of the field. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Analysis of biogenic carbonyl compounds in rainwater by stir bar sorptive extraction technique with chemical derivatization and gas chromatography-mass spectrometry.

    PubMed

    Pang, Xiaobing; Lewis, Alastair C; Shaw, Marvin D

    2017-02-01

    Stir bar sorptive extraction is a powerful technique for the extraction and analysis of organic compounds in aqueous matrices. Carbonyl compounds are ubiquitous components in rainwater, however, it is a major challenge to accurately identify and sensitively quantify carbonyls from rainwater due to the complex matrix. A stir bar sorptive extraction technique was developed to efficiently extract carbonyls from aqueous samples following chemical derivatization by O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine hydrochloride. Several commercial stir bars in two sizes were used to simultaneously measure 29 carbonyls in aqueous samples with detection by gas chromatography with mass spectrometry. A 100 mL aqueous sample was extracted by stir bars and the analytes on stir bars were desorbed into a 2 mL solvent solution in an ultrasonic bath. The preconcentration Coefficient for different carbonyls varied between 30 and 45 times. The limits of detection of stir bar sorptive extraction with gas chromatography mass spectrometry for carbonyls (10-30 ng/L) were improved by ten times compared with other methods such as gas chromatography with electron capture detection and stir bar sorptive extraction with high-performance liquid chromatography and mass spectrometry. The technique was used to determine carbonyls in rainwater samples collected in York, UK, and 20 carbonyl species were quantified including glyoxal, methylglyoxal, isobutenal, 2-hydroxy ethanal.

  5. Characterization of the Potent Odorants Contributing to the Characteristic Aroma of Matcha by Gas Chromatography-Olfactometry Techniques.

    PubMed

    Baba, Ryoko; Amano, Yohei; Wada, Yoshiyuki; Kumazawa, Kenji

    2017-03-31

    The odorants contributing to the characteristic aroma of matcha were investigated by analysis of the headspace samples and the volatile fractions prepared by a combination of solvent extraction and the SAFE techniques using three matcha powders of different grades (high, medium, and low). Gas chromatography-olfactometry of the headspace samples (GCO-H) and aroma extract dilution analysis (AEDA) applied to the volatile fractions revealed 16 (FD factor ≥1) and 39 (FD factor ≥4(3)) odor-active peaks, respectively. Among them, 14 and 37 of the odorants, most of which were newly detected in matcha, were identified or tentatively identified by GC-MS and GC-O, respectively. By comparing the perceived odorants of three matcha powders, it was revealed that eight compounds with sweet, green, metallic, and floral notes showed high flavor dilution (FD) factors irrespective of the grades. In addition, some odorants were suggested to influence the characteristic aroma of each grade. Furthermore, trans-4,5-epoxy-(E)-2-decenal, one of the potent odorants of matcha, was revealed to exist as a racemic mixture in matcha. This result suggested that trans-4,5-epoxy-(E)-2-decenal is formed by a nonenzymatic reaction in matcha, different from that in black tea, and that the unique manufacturing process of matcha has a close connection with its formation.

  6. Quantification of 4-Methylimidazole in soft drinks, sauces and vinegars of Greek market using two liquid chromatography techniques.

    PubMed

    Tzatzarakis, Manolis N; Vakonaki, Elena; Moti, Sofia; Alegakis, Athanasios; Tsitsimpikou, Christina; Tsakiris, Ioannis; Goumenou, Marina; Nosyrev, Alexander E; Rizos, Apostolos K; Tsatsakis, Aristidis M

    2017-09-01

    The substance 4-methylimidazole (4-MEI) has raised several concerns regarding its toxicity to humans, although no harmonized classification has yet been decided. The regulatory limits for food products set by various authorities in Europe and the USA differ considerably. The purpose of the present study is to compare two liquid chromatography techniques in order to determine the levels of 4-MEI in food products from the Greek market and roughly estimate the possible exposure and relevant health risk for the consumers. A total of thirty-four samples (soft drinks, beers, balsamic vinegars, energy drinks and sauces) were collected and analyzed. The quality parameters for both analytical methodologies (linearity, accuracy, inter day precision, recovery) are presented. No detectable levels of 4-MEI are found in beers and soft drink samples, other than cola type. On the other hand, 4-MEI was detected in all cola type soft drinks (15.8-477.0 ng/ml), energy drinks (57.1%, 6.6-22.5 ng/ml) and vinegar samples (66.7%, 9.7-3034.7 ng/ml), while only one of the sauce samples was found to have a detectable level of 17.5 ng/ml 4-MEI. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Glycopeptide Site Heterogeneity and Structural Diversity Determined by Combined Lectin Affinity Chromatography/IMS/CID/MS Techniques

    NASA Astrophysics Data System (ADS)

    Zhu, Feifei; Trinidad, Jonathan C.; Clemmer, David E.

    2015-07-01

    Glycopeptides from a tryptic digest of chicken ovomucoid were enriched using a simplified lectin affinity chromatography (LAC) platform, and characterized by high-resolution mass spectrometry (MS) as well as ion mobility spectrometry (IMS)-MS. The LAC platform effectively enriched the glycoproteome, from which a total of 117 glycopeptides containing 27 glycan forms were identified for this protein. IMS-MS analysis revealed a high degree of glycopeptide site heterogeneity. Comparison of the IMS distributions of the glycopeptides from different charge states reveals that higher charge states allow more structures to be resolved. Presumably the repulsive interactions between charged sites lead to more open configurations, which are more readily separated compared with the more compact, lower charge state forms of the same groups of species. Combining IMS with collision induced dissociation (CID) made it possible to determine the presence of isomeric glycans and to reconstruct their IMS profiles. This study illustrates a workflow involving hybrid techniques for determining glycopeptide site heterogeneity and evaluating structural diversity of glycans and glycopeptides.

  8. Achiral and Chiral Separations Using Micellar Electrokinetic Chromatography, Polyelectrolyte Multilayer Coatings, and Mixed Mode Separation Techniques with Molecular Micelles

    PubMed Central

    Luces, Candace A.; Warner, Isiah M.

    2014-01-01

    Mixed mode separation using a combination of micellar electrokinetic chromatography (MEKC) and polyelectrolyte multilayer (PEM) coatings is herein reported for the separation of achiral and chiral analytes. Many analytes are difficult to separate by MEKC and PEM coatings alone. Therefore, the implementation of a mixed mode separation provides several advantages for overcoming the limitations of these well-established methods. In this study, it was observed that achiral separations using MEKC and PEM coatings individually resulted in partial resolution of 8 very similar aryl ketones when the molecular micelle (sodium poly(N-undecanoyl-l-glycinate) (poly-SUG)) concentration was varied from 0.25% – 1.00% (w/v) and the bilayer number varied from 2 – 4. However, when mixed mode separation was introduced, baseline resolution was achieved for all 8 analytes. In the case of chiral separations, temazepam, aminoglutethimide, benzoin, benzoin methyl ether and coumachlor were separated using the three separation techniques. For chiral separations, the chiral molecular micelle, sodium poly(N-undecanoyl-l-leucylvalinate) (poly-l-SULV), was employed at concentrations of 0.25–1.50% (w/v) for both MEKC and PEM coatings. Overall, the results revealed partial separation with MEKC and PEM coatings individually. However, mixed mode separation enabled baseline separation of each chiral mixture. The separation of achiral and chiral compounds from different compound classes demonstrates the versatility of this mixed mode approach. PMID:20155738

  9. Inter-comparison of laser photoacoustic spectroscopy and gas chromatography techniques for measurements of ethene in the atmosphere.

    PubMed

    Kuster, William C; Harren, Frans J M; de Gouw, Joost A

    2005-06-15

    Laser photoacoustic spectroscopy (LPAS) is highly suitable for the detection of ethene in air due to the overlap between its strongest absorption lines and the wavelengths accessible by high-powered CO2 lasers. Here, we test the ability of LPAS to measure ethene in ambient air by comparing the measurements in urban air with those from a gas chromatography flame-ionization detection (GC-FID) instrument. Over the course of several days, we obtained quantitative agreement between the two measurements. Over this period, the LPAS instrument had a positive offset of 330 +/- 140 pptv (parts-per-trillion by volume) relative to the GC-FID instrument, possibly caused by interference from other species. The detection limit of the LPAS instrument is currently estimated around 1 ppbv and is limited by this offset and the statistical noise in the data. We conclude that LPAS has the potential to provide fast-response measurements of ethene in the atmosphere, with significant advantages over existing techniques when measuring from moving platforms and in the vicinity of emission sources.

  10. Characterisation and discrimination of various types of lac resin using gas chromatography mass spectrometry techniques with quaternary ammonium reagents.

    PubMed

    Sutherland, K; del Río, J C

    2014-04-18

    A variety of lac resin samples obtained from artists' suppliers, industrial manufacturers, and museum collections were analysed using gas chromatography mass spectrometry (GCMS) and reactive pyrolysis GCMS with quaternary ammonium reagents. These techniques allowed a detailed chemical characterisation of microgram-sized samples, based on the detection and identification of derivatives of the hydroxy aliphatic and cyclic (sesquiterpene) acids that compose the resin. Differences in composition could be related to the nature of the resin, e.g. wax-containing (unrefined), bleached, or aged samples. Furthermore, differences in the relative abundances of aliphatic hydroxyacids appear to be associated with the biological source of the resin. The diagnostic value of newly characterised lac components, including 8-hydroxyacids, is discussed here for the first time. Identification of derivatised components was aided by AMDIS deconvolution software, and discrimination of samples was enhanced by statistical evaluation of data using principal component analysis. The robustness of the analyses, together with the minimal sample size required, make these very powerful approaches for the characterisation of lac resin in museum objects. The value of such analyses for enhancing the understanding of museum collections is illustrated by two case studies of objects in the collection of the Philadelphia Museum of Art: a restorer's varnish on a painting by Luca Signorelli, and a pictorial inlay in an early nineteenth-century High Chest by George Dyer. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Interpreting comprehensive two-dimensional gas chromatography using peak topography maps with application to petroleum forensics.

    PubMed

    Ghasemi Damavandi, Hamidreza; Sen Gupta, Ananya; Nelson, Robert K; Reddy, Christopher M

    2016-01-01

    Comprehensive two-dimensional gas chromatography [Formula: see text] provides high-resolution separations across hundreds of compounds in a complex mixture, thus unlocking unprecedented information for intricate quantitative interpretation. We exploit this compound diversity across the [Formula: see text] topography to provide quantitative compound-cognizant interpretation beyond target compound analysis with petroleum forensics as a practical application. We focus on the [Formula: see text] topography of biomarker hydrocarbons, hopanes and steranes, as they are generally recalcitrant to weathering. We introduce peak topography maps (PTM) and topography partitioning techniques that consider a notably broader and more diverse range of target and non-target biomarker compounds compared to traditional approaches that consider approximately 20 biomarker ratios. Specifically, we consider a range of 33-154 target and non-target biomarkers with highest-to-lowest peak ratio within an injection ranging from 4.86 to 19.6 (precise numbers depend on biomarker diversity of individual injections). We also provide a robust quantitative measure for directly determining "match" between samples, without necessitating training data sets. We validate our methods across 34 [Formula: see text] injections from a diverse portfolio of petroleum sources, and provide quantitative comparison of performance against established statistical methods such as principal components analysis (PCA). Our data set includes a wide range of samples collected following the 2010 DeepwaterHorizon disaster that released approximately 160 million gallons of crude oil from the Macondo well (MW). Samples that were clearly collected following this disaster exhibit statistically significant match [Formula: see text] using PTM-based interpretation against other closely related sources. PTM-based interpretation also provides higher differentiation between closely correlated but distinct sources than obtained using

  12. A VIKOR Technique with Applications Based on DEMATEL and ANP

    NASA Astrophysics Data System (ADS)

    Ou Yang, Yu-Ping; Shieh, How-Ming; Tzeng, Gwo-Hshiung

    In multiple criteria decision making (MCDM) methods, the compromise ranking method (named VIKOR) was introduced as one applicable technique to implement within MCDM. It was developed for multicriteria optimization of complex systems. However, few papers discuss conflicting (competing) criteria with dependence and feedback in the compromise solution method. Therefore, this study proposes and provides applications for a novel model using the VIKOR technique based on DEMATEL and the ANP to solve the problem of conflicting criteria with dependence and feedback. In addition, this research also uses DEMATEL to normalize the unweighted supermatrix of the ANP to suit the real world. An example is also presented to illustrate the proposed method with applications thereof. The results show the proposed method is suitable and effective in real-world applications.

  13. Group decision-making techniques for natural resource management applications

    USGS Publications Warehouse

    Coughlan, Beth A.K.; Armour, Carl L.

    1992-01-01

    This report is an introduction to decision analysis and problem-solving techniques for professionals in natural resource management. Although these managers are often called upon to make complex decisions, their training in the natural sciences seldom provides exposure to the decision-making tools developed in management science. Our purpose is to being to fill this gap. We present a general analysis of the pitfalls of group problem solving, and suggestions for improved interactions followed by the specific techniques. Selected techniques are illustrated. The material is easy to understand and apply without previous training or excessive study and is applicable to natural resource management issues.

  14. Application of thermoluminescence technique to identify radiation processed foods

    NASA Astrophysics Data System (ADS)

    Kiyak, N.

    1995-02-01

    Research studies reported by various authors have shown that a few methods one of which is thermoluminescence technique- may be suitable for identification of some certain irradiated spicies and food containing bones. This study is an application of the thermoluminescence technique for identifying the irradiated samples. The investigation was carried out on different types of foodstuffs such as onions, potatoes and kiwi. Measurements show that the technique can be applied as a reliable method to distinguish the irradiated food products from non-irradiated ones. The results demonstrate also that it is possible to use this method for determining the absorbed dose of irradiated samples from the established dose-effect curve.

  15. Multiple inert gas elimination technique by micropore membrane inlet mass spectrometry--a comparison with reference gas chromatography.

    PubMed

    Kretzschmar, Moritz; Schilling, Thomas; Vogt, Andreas; Rothen, Hans Ulrich; Borges, João Batista; Hachenberg, Thomas; Larsson, Anders; Baumgardner, James E; Hedenstierna, Göran

    2013-10-15

    The mismatching of alveolar ventilation and perfusion (VA/Q) is the major determinant of impaired gas exchange. The gold standard for measuring VA/Q distributions is based on measurements of the elimination and retention of infused inert gases. Conventional multiple inert gas elimination technique (MIGET) uses gas chromatography (GC) to measure the inert gas partial pressures, which requires tonometry of blood samples with a gas that can then be injected into the chromatograph. The method is laborious and requires meticulous care. A new technique based on micropore membrane inlet mass spectrometry (MMIMS) facilitates the handling of blood and gas samples and provides nearly real-time analysis. In this study we compared MIGET by GC and MMIMS in 10 piglets: 1) 3 with healthy lungs; 2) 4 with oleic acid injury; and 3) 3 with isolated left lower lobe ventilation. The different protocols ensured a large range of normal and abnormal VA/Q distributions. Eight inert gases (SF6, krypton, ethane, cyclopropane, desflurane, enflurane, diethyl ether, and acetone) were infused; six of these gases were measured with MMIMS, and six were measured with GC. We found close agreement of retention and excretion of the gases and the constructed VA/Q distributions between GC and MMIMS, and predicted PaO2 from both methods compared well with measured PaO2. VA/Q by GC produced more widely dispersed modes than MMIMS, explained in part by differences in the algorithms used to calculate VA/Q distributions. In conclusion, MMIMS enables faster measurement of VA/Q, is less demanding than GC, and produces comparable results.

  16. Bioanalytical applications of isothermal nucleic acid amplification techniques.

    PubMed

    Deng, Huimin; Gao, Zhiqiang

    2015-01-01

    The most popular in vitro nucleic acid amplification techniques like polymerase chain reaction (PCR) including real-time PCR are costly and require thermocycling, rendering them unsuitable for uses at point-of-care. Highly efficient in vitro nucleic acid amplification techniques using simple, portable and low-cost instruments are crucial in disease diagnosis, mutation detection and biodefense. Toward this goal, isothermal amplification techniques that represent a group of attractive in vitro nucleic acid amplification techniques for bioanalysis have been developed. Unlike PCR where polymerases are easily deactivated by thermally labile constituents in a sample, some of the isothermal nucleic acid amplification techniques, such as helicase-dependent amplification and nucleic acid sequence-based amplification, enable the detection of bioanalytes with much simplified protocols and with minimal sample preparations since the entire amplification processes are performed isothermally. This review focuses on the isothermal nucleic acid amplification techniques and their applications in bioanalytical chemistry. Starting off from their amplification mechanisms and significant properties, the adoption of isothermal amplification techniques in bioanalytical chemistry and their future perspectives are discussed. Representative examples illustrating the performance and advantages of each isothermal amplification technique are discussed along with some discussion on the advantages and disadvantages of each technique.

  17. Phytochemical and morphological characterization of hop (Humulus lupulus L.) cones over five developmental stages using high performance liquid chromatography coupled to time-of-flight mass spectrometry, ultrahigh performance liquid chromatography photodiode array detection, and light microscopy techniques.

    PubMed

    Kavalier, Adam R; Litt, Amy; Ma, Chunhui; Pitra, Nicholi J; Coles, Mark C; Kennelly, Edward J; Matthews, Paul D

    2011-05-11

    Hop (Humulus lupulus L.) inflorescences, commonly known as "hop cones", are prized for their terpenophenolic contents, used in beer production and, more recently, in biomedical applications. In this study we investigated morphological and phytochemical characteristics of hop cones over five developmental stages, using liquid chromatography coupled to time-of-flight mass spectrometry (LC-TOF-MS), and ultrahigh performance liquid chromatography photodiode array detection (UHPLC-PDA) methods to quantitate 21 polyphenolics and seven terpenophenolics. Additionally, we used light microscopy to correlate phytochemical quantities with changes in the morphology of the cones. Significant increases in terpenophenolics, concomitant with glandular trichome development and associated gross morphological changes, were mapped over development to fluctuations in contents of polyphenolic constituents and their metabolic precursor compounds. The methods reported here can be used for targeted metabolic profiling of flavonoids, phenolic acids, and terpenophenolics in hops, and are applicable to quantitation in other crops.

  18. Sample Processing technique onboard ExoMars (MOMA) to analyze organic compounds by Gas Chromatography-Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Buch, A.; Freissinet, C.; Sternberg, R.; Szopa, C.; Coll, P. J.; Brault, A.; Pinnick, V.; Siljeström, S.; Raulin, F.; Steininger, H.; Goesmann, F.; MOMA Team

    2011-12-01

    With the aim of separating and detecting organic compounds from Martian soil onboard the Mars Organic Molecule Analyzer (MOMA) experiment of the ExoMars 2018 upcoming joint ESA/NASA mission, we have developed three different space compatible sample preparation techniques compatible with space missions, able to extract and analyze by GC-MS a wide range of volatile and refractory compounds, including chirality analysis. Then, a sample processing utilizing three derivatization/extraction reactions has been carried out. The first reaction is based on a silyl reagent N-Methyl-N- (Tert-Butyldimethylsilyl)trifluoroacetamide (MTBSTFA) [1], the second one, N,N-Dimethylformamide Dimethylacetal (DMF-DMA) [2,3] is dedicated to the chirality detection and the third one is a thermochemolysis based on the use of tetramethylammoniumhydroxide (TMAH). The sample processing system is performed in an oven, dedicated to the MOMA experiment containing the solid sample (50-100mg). The internal temperature of the oven ranges from 20 to 900 °C. The extraction step is achieved by using thermodesorption in the range of 100 to 300°C for 5 to 20 min. Then, the chemical derivatization of the extracted compounds is performed directly on the soil sample by using a derivatyization capsule which contains a mixture of MTBSTFA-DMF or DMF-DMA solution when enantiomeric separation is required. By decreasing the polarity of the targeted molecules, this step allows their volatilization at a temperature below 250°C without any thermal degradation. Once derivatized, the volatile target molecules are trapped in a chemical trap and promptly desorbed into the gas chromatograph coupled to a mass spectrometer. Thermochemolysis is directly performed in the oven at 400°C during 5 min with a 25% (w/w) methanol solution of tetramethylammonium hydroxide (TMAH). Then, pyrolysis in the presence of TMAH allows both an efficient cleavage of polar bonds and the subsequent methylation of COOH, OH and NH2 groups, hence

  19. A concise review of applications of micellar liquid chromatography to study biologically active compounds.

    PubMed

    Stępnik, Katarzyna E

    2017-01-01

    The features of micellar systems are outstanding compared with conventional RP-LC ones. Therefore, the unique properties of micellar chromatography (MLC) are widely recognized. In this short review the applicability of MLC as an in vitro method for the determination of biological activity is discussed. For this purpose many specific examples of MLC applications supported by the theoretical backgrounds of the cited biological activity areas as well as the factors affecting them are presented. This study collects and organizes the most important references of bioactivity determination which were created both recently and in the past, using the MLC method. Although there are many papers on the MLC there is no literature review focused particularly on its applicability in the study of biological activity of various compounds. This work can be treated as a significant review of so far published papers which particularly emphasizes the importance of MLC as in vitro method for determination of bioactivity of different compounds. Copyright © 2016 John Wiley & Sons, Ltd.

  20. Applications of monolithic columns in liquid chromatography-based clinical chemistry assays.

    PubMed

    Bunch, Dustin R; Wang, Sihe

    2011-08-01

    Monolithic columns have slowly been applied to HPLC methods for clinical chemistry testing in the last 10 years. The application areas include therapeutic drug monitoring, drugs of abuse, vitamins, porphyrins, and steroids. In comparison with conventional particulate columns, the monolithic columns may offer shorter chromatography time, more robustness, and better resolution for certain analytes. The potential drawback of large mobile phase consumption may be improved with smaller id columns, which are currently on the market. Methods covered in this review are those searchable in PubMed up to December 2010. This review highlights the emergence of monolithic column technology in HPLC methods used for clinical chemistry testing. The goals of this review are threefold: (i) To identify the areas of clinical chemistry that analytical monolithic columns have been used in HPLC methods. (ii) To demonstrate the application of analytical monolithic columns in HPLC methods using different detection systems. (iii) To discuss the advantages and limitations of the monolithic columns compared with particulate columns in the clinical chemistry applications.

  1. Metal Nanoparticles Protected with Monolayers: Applications for Chemical Vapor Sensing and Gas Chromatography

    SciTech Connect

    Grate, Jay W.; Nelson, David A.; Skaggs, Rhonda L.; Synovec, Robert E.; Gross, Gwen M.

    2004-03-31

    Nanoparticles and nanoparticle-based materials are of considerable interest for their unique properties and their potential for use in a variety of applications. Metal nanoparticles, in which each particle’s surface is coated with a protective organic monolayer, are of particular interest because the surface monolayer stabilizes them relative to aggregation and they can be taken up into solutions.(1-4) As a result they can be processed into thin films for device applications. We will refer to these materials as monolayer-protected nanoparticles, or MPNs. Typically the metal is gold, the organic layer is a self-assembled thiol layer, and this composition will be assumed throughout the remainder of this chapter. A diversity of materials and properties is readily accessible by straightforward synthetic procedures, either by the structures of the monolayer-forming thiols used in the synthesis or by post-synthetic modifications of the monolayers. A particularly promising application for these materials is as selective layers on chemical vapor sensors. In this role, the thin film of MPNs on the device surface serves to collect and concentrate gas molecules at the sensor’s surface. Their sorptive properties also lend them to use as new nanostructured gas chromatographic stationary phases. This chapter will focus on the sorptive properties of MPNs as they relate to chemical sensors and gas chromatography.

  2. Direct and comprehensive analysis of ginsenosides and diterpene alkaloids in Shenfu injection by combinatory liquid chromatography-mass spectrometric techniques.

    PubMed

    Yang, Hua; Liu, Lei; Gao, Wen; Liu, Ke; Qi, Lian-Wen; Li, Ping

    2014-04-01

    Shenfu injection (SFI) is a widely used Chinese herbal formulation for cardiac diseases prepared from red ginseng and processed aconite root. Clinical observations and pharmacological effects on SFI have been well investigated. Chemical analysis and quality control studies of this formulation, however, are relatively limited, especially regarding toxic aconite alkaloids. In this work, a high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (HPLC-QTOF MS) method was applied to comprehensive analysis of constituents in SFI. Highly sensitive MS allows direct analysis of injections without additional sample pretreatment required. Using diagnostic ions and fragmentation rules, we identified 23 trace diterpene alkaloids, nineteen ginseng saponins, one panaxytriol, and one 5-hydroxymethylfurfural in SFI. A LC-MS method with selected ion monitoring was then used to quantify 24 major alkaloids and ginsenosides. The method was validated in terms of linearity, accuracy and precision. Especially, the limits of quantification were low to 0.4-18ng/mL for diterpene alkaloids. The total concentrations of saponins and alkaloids were about 676-742μg/mL and 3-7μg/mL in five batches of SFI samples, respectively. Finally, cosine ratio and euclidean distance were introduced to evaluate the batch-to-batch reproducibility of SFI samples, and the results demonstrated high quality consistency. Global identification and quantification of complex constituents based on LC-MS promises wide applications in quality control and batch monitoring for herbal products.

  3. Novel mesoporous carbonaceous materials: Synthesis, characterization and applications in liquid chromatography

    NASA Astrophysics Data System (ADS)

    Li, Zuojiang

    The ability to control the porous structure in carbonaceous materials has been significantly improved in the past decade due to the appearance of new synthetic routes and novel templating materials. In this dissertation, novel mesoporous carbonaceous materials with controlled structural and surface properties were prepared and investigated using low temperature nitrogen adsorption, thermal analysis, X-ray diffraction and other analytical techniques. The performance of these novel mesoporous carbons in liquid chromatography was also investigated. Carbons with extremely high mesoporosity were synthesized by using mesophase pitch and polyacrylonitrile as precursors in the silica gel templating method, which led to a dramatic reduction of microporosity and high carbonization yield. The most important achievement of this dissertation is the initiation of a colloidal imprinting technique, in which spherical pores were created in the particles of mesophase pitch by using silica colloids of proper size. This method allows us to prepare carbons with uniform spherical pores in the range of 7--70 nm and narrow pore size distribution, filling the pore size gap between carbons templated with ordered silicas and colloidal silica crystals. The introduction of air stabilization further improved the ability to control the pore development at a given stage in the imprinting process. For the first time, carbon particles with mesoporous shell/nonporous core structure were obtained. In this way, carbons with controlled pore size, surface area, pore volume and particle size were synthesized. Moreover, the colloidal imprinting technique was extended to a more general imprinting concept, in which porous particles were used to obtain carbon particles having ordered or disordered structure on their surface. Graphitization of the imprinted carbons provided carbonaceous materials of tailored mesopores and graphitic structure. Also, this high-temperature treatment removed surface functional

  4. Microwave-assisted derivatization: application to steroid profiling by gas chromatography/mass spectrometry.

    PubMed

    Casals, Gregori; Marcos, Josep; Pozo, Oscar J; Alcaraz, José; Martínez de Osaba, María Jesús; Jiménez, Wladimiro

    2014-06-01

    Gas chromatography-mass spectrometry (GC-MS) remains as the gold-standard technique for the study of the steroid metabolome. A main limitation is the need of performing a derivatization step since incubation with strong silylations agents for long periods of time (usually 16 h) is required for the derivatization of hindered hydroxyls present in some steroids of interest. In the present work, a rapid, simple and reproducible microwave-assisted derivatization method was developed. In the method, 36 steroids already treated with methoxyamine (2% in pyridine) were silylated with 50 μl of N-trimethylsilylimidazole by using microwave irradiation, and the formed methyloxime-trimethylsilyl derivatives were analyzed by GC-MS. Microwave power and derivatization time silylation conditions were optimized being the optimum conditions 600 W and 3 min respectively. In order to evaluate the usefulness of this technique, the urine steroid profiles for 20 healthy individuals were analyzed. The results of a comparison of microwave irradiation with the classical heating protocol showed similar derivatization yields, thus suggesting that microwave-assisted silylation is a valid tool for the rapid steroid metabolome study.

  5. Application of the cell sheet technique in tissue engineering

    PubMed Central

    CHEN, GUANGNAN; QI, YIYING; NIU, LIE; DI, TUOYU; ZHONG, JINWEI; FANG, TINGTING; YAN, WEIQI

    2015-01-01

    The development and application of the tissue engineering technique has shown a significant potential in regenerative medicine. However, the limitations of conventional tissue engineering methods (cell suspensions, scaffolds and/or growth factors) restrict its application in certain fields. The novel cell sheet technique can overcome such disadvantages. Cultured cells can be harvested as intact sheets without the use of proteolytic enzymes, such as trypsin or dispase, which can result in cell damage and loss of differentiated phenotypes. The cell sheet is a complete layer, which contains extracellular matrix, ion channel, growth factor receptors, nexin and other important cell surface proteins. Mesenchymal stem cells (MSCs), which have the potential for multiple differentiation, are promising candidate seed cells for tissue engineering. The MSC sheet technique may have potential in the fields of regenerative medicine and tissue engineering in general. Additionally, induced pluripotent stem cell and embryonic stem cell-derived cell sheets have been proposed for tissue regeneration. Currently, the application of cell sheet for tissue reconstruction includes: Direct recipient sites implantation, superposition of cell sheets to construct three-dimensional structure for implantation, or cell sheet combined with scaffolds. The present review discusses the progress in cell sheet techniques, particularly stem cell sheet techniques, in tissue engineering. PMID:26623011

  6. DYNAMIC 3D QSAR TECHNIQUES: APPLICATIONS IN TOXICOLOGY

    EPA Science Inventory

    Two dynamic techniques recently developed to account for conformational flexibility of chemicals in 3D QSARs are presented. In addition to the impact of conformational flexibility of chemicals in 3D QSAR models, the applicability of various molecular descriptors is discussed. The...

  7. 48 CFR 9904.412-50 - Techniques for application.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    .... 9904.412-50 Section 9904.412-50 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD... ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.412-50 Techniques for application. (a) Components of... identified part of the pension cost of a cost accounting period and shall be included in equal...

  8. 48 CFR 9904.413-50 - Techniques for application.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    .... 9904.413-50 Section 9904.413-50 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD... ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.413-50 Techniques for application. (a) Assignment of actuarial gains and losses. (1) In accordance with the provisions of Cost Accounting Standard...

  9. 48 CFR 9904.408-50 - Techniques for application.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    .... 9904.408-50 Section 9904.408-50 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD... ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.408-50 Techniques for application. (a) Determinations... determination shall be made beginning with the first cost accounting period to which such new or changed plan...

  10. Dynamic mechanical analysis: A practical introduction to techniques and applications

    SciTech Connect

    Menard, K.

    1999-01-01

    This book introduces DMA, its history, and its current position as part of thermal analysis on polymers. It discusses major types of instrumentation, including oscillatory rotational, oscillatory axial, and torsional pendulum. It also describes analytical techniques in terms of utility, quality of data, methods of calibration, and suitability for different types of materials and assesses applications for thermoplastics, thermosetting systems, and thermosets.

  11. APPLICATION OF STABLE ISOTOPE TECHNIQUES TO AIR POLLUTION RESEARCH

    EPA Science Inventory

    Stable isotope techniques provide a robust, yet under-utilized tool for examining pollutant effects on plant growth and ecosystem function. Here, we survey a range of mixing model, physiological and system level applications for documenting pollutant effects. Mixing model examp...

  12. Photographic Enlargement of Printed Music: Technique, Application, and Implications.

    ERIC Educational Resources Information Center

    Flynn, Pauline T.; Rich, A. Jeanette

    1982-01-01

    Addressed a need for enlargement of music when retirement home residents were deprived of a self-fulfillment opportunity from choir activities due to failing eyesight. A photographic process yielded the needed feasible large reproductions. Innovative application of this technique affords wide-ranging potential for positive benefit beyond music…

  13. Application of Data Collection Techniques by Human Performance Technology Practitioners

    ERIC Educational Resources Information Center

    Duan, Minjing

    2011-01-01

    By content-analyzing 22 published cases from a variety of professional and academic books and journals, this study examines the status quo of human performance technology (HPT) practitioners' application of five major data collection techniques in their everyday work: questionnaire, interview, focus group, observation, and document collection. The…

  14. Application of Data Collection Techniques by Human Performance Technology Practitioners

    ERIC Educational Resources Information Center

    Duan, Minjing

    2011-01-01

    By content-analyzing 22 published cases from a variety of professional and academic books and journals, this study examines the status quo of human performance technology (HPT) practitioners' application of five major data collection techniques in their everyday work: questionnaire, interview, focus group, observation, and document collection. The…

  15. 48 CFR 9904.404-50 - Techniques for application.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    .... 9904.404-50 Section 9904.404-50 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD, OFFICE OF FEDERAL PROCUREMENT POLICY, OFFICE OF MANAGEMENT AND BUDGET PROCUREMENT PRACTICES AND COST ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.404-50 Techniques for application. (a) The cost...

  16. 48 CFR 9904.401-50 - Techniques for application.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    .... 9904.401-50 Section 9904.401-50 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD, OFFICE OF FEDERAL PROCUREMENT POLICY, OFFICE OF MANAGEMENT AND BUDGET PROCUREMENT PRACTICES AND COST ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.401-50 Techniques for application. (a) The...

  17. 48 CFR 9904.401-50 - Techniques for application.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    .... 9904.401-50 Section 9904.401-50 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD, OFFICE OF FEDERAL PROCUREMENT POLICY, OFFICE OF MANAGEMENT AND BUDGET PROCUREMENT PRACTICES AND COST ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.401-50 Techniques for application. (a) The...

  18. 48 CFR 9904.402-50 - Techniques for application.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    .... 9904.402-50 Section 9904.402-50 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD, OFFICE OF FEDERAL PROCUREMENT POLICY, OFFICE OF MANAGEMENT AND BUDGET PROCUREMENT PRACTICES AND COST ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.402-50 Techniques for application. (a) The...

  19. 48 CFR 9904.401-50 - Techniques for application.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    .... 9904.401-50 Section 9904.401-50 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD, OFFICE OF FEDERAL PROCUREMENT POLICY, OFFICE OF MANAGEMENT AND BUDGET PROCUREMENT PRACTICES AND COST ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.401-50 Techniques for application. (a) The...

  20. 48 CFR 9904.402-50 - Techniques for application.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    .... 9904.402-50 Section 9904.402-50 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD, OFFICE OF FEDERAL PROCUREMENT POLICY, OFFICE OF MANAGEMENT AND BUDGET PROCUREMENT PRACTICES AND COST ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.402-50 Techniques for application. (a) The...

  1. 48 CFR 9904.402-50 - Techniques for application.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    .... 9904.402-50 Section 9904.402-50 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD, OFFICE OF FEDERAL PROCUREMENT POLICY, OFFICE OF MANAGEMENT AND BUDGET PROCUREMENT PRACTICES AND COST ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.402-50 Techniques for application. (a) The...

  2. 48 CFR 9904.404-50 - Techniques for application.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    .... 9904.404-50 Section 9904.404-50 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD, OFFICE OF FEDERAL PROCUREMENT POLICY, OFFICE OF MANAGEMENT AND BUDGET PROCUREMENT PRACTICES AND COST ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.404-50 Techniques for application. (a) The cost...

  3. 48 CFR 9904.406-50 - Techniques for application.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    .... 9904.406-50 Section 9904.406-50 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD, OFFICE OF FEDERAL PROCUREMENT POLICY, OFFICE OF MANAGEMENT AND BUDGET PROCUREMENT PRACTICES AND COST ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.406-50 Techniques for application. (a) The cost of...

  4. 48 CFR 9904.405-50 - Techniques for application.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    .... 9904.405-50 Section 9904.405-50 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD, OFFICE OF FEDERAL PROCUREMENT POLICY, OFFICE OF MANAGEMENT AND BUDGET PROCUREMENT PRACTICES AND COST ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.405-50 Techniques for application. (a) The detail...

  5. 48 CFR 9904.405-50 - Techniques for application.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    .... 9904.405-50 Section 9904.405-50 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD, OFFICE OF FEDERAL PROCUREMENT POLICY, OFFICE OF MANAGEMENT AND BUDGET PROCUREMENT PRACTICES AND COST ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.405-50 Techniques for application. (a) The detail...

  6. DYNAMIC 3D QSAR TECHNIQUES: APPLICATIONS IN TOXICOLOGY

    EPA Science Inventory

    Two dynamic techniques recently developed to account for conformational flexibility of chemicals in 3D QSARs are presented. In addition to the impact of conformational flexibility of chemicals in 3D QSAR models, the applicability of various molecular descriptors is discussed. The...

  7. Basic Technology and Clinical Application Technique of Magnetocardiograph

    NASA Astrophysics Data System (ADS)

    Kandori, Akihiko

    The Magnetocardiograph (MCG) is a new non-invasive tool for diagnosing the heart disease. MCG has a potential to detect a ischemia and arrhythmic focus accurately. In this article, we introduce the basic technology of MCG system and clinical application technique.

  8. Photographic Enlargement of Printed Music: Technique, Application, and Implications.

    ERIC Educational Resources Information Center

    Flynn, Pauline T.; Rich, A. Jeanette

    1982-01-01

    Addressed a need for enlargement of music when retirement home residents were deprived of a self-fulfillment opportunity from choir activities due to failing eyesight. A photographic process yielded the needed feasible large reproductions. Innovative application of this technique affords wide-ranging potential for positive benefit beyond music…

  9. Techniques for Field Application of Lingual Ultrasound Imaging

    ERIC Educational Resources Information Center

    Gick, Bryan; Bird, Sonya; Wilson, Ian

    2005-01-01

    Techniques are discussed for using ultrasound for lingual imaging in field-related applications. The greatest challenges we have faced distinguishing the field setting from the laboratory setting are the lack of controlled head/transducer movement, and the related issue of tissue compression. Two experiments are reported. First, a pilot study…

  10. APPLICATION OF STABLE ISOTOPE TECHNIQUES TO AIR POLLUTION RESEARCH

    EPA Science Inventory

    Stable isotope techniques provide a robust, yet under-utilized tool for examining pollutant effects on plant growth and ecosystem function. Here, we survey a range of mixing model, physiological and system level applications for documenting pollutant effects. Mixing model examp...

  11. IBM Applications and Techniques of Operations Research. A Selected Bibliography.

    ERIC Educational Resources Information Center

    International Business Machines Corp., White Plains, NY. Data Processing Div.

    This bibliography on the tools and applications of operations research, management science, industrial engineering, and systems engineering lists many entries which appeared between 1961 and 1966 in 186 periodicals and trade journals. Twenty-six texts in operations research are also listed along with an indication as to which of 37 techniques or…

  12. Techniques for Field Application of Lingual Ultrasound Imaging

    ERIC Educational Resources Information Center

    Gick, Bryan; Bird, Sonya; Wilson, Ian

    2005-01-01

    Techniques are discussed for using ultrasound for lingual imaging in field-related applications. The greatest challenges we have faced distinguishing the field setting from the laboratory setting are the lack of controlled head/transducer movement, and the related issue of tissue compression. Two experiments are reported. First, a pilot study…

  13. 48 CFR 9904.403-50 - Techniques for application.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    .... 9904.403-50 Section 9904.403-50 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD, OFFICE OF FEDERAL PROCUREMENT POLICY, OFFICE OF MANAGEMENT AND BUDGET PROCUREMENT PRACTICES AND COST ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.403-50 Techniques for application. (a)(1)...

  14. 48 CFR 9904.404-50 - Techniques for application.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    .... 9904.404-50 Section 9904.404-50 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD, OFFICE OF FEDERAL PROCUREMENT POLICY, OFFICE OF MANAGEMENT AND BUDGET PROCUREMENT PRACTICES AND COST ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.404-50 Techniques for application. (a) The cost...

  15. 48 CFR 9904.411-50 - Techniques for application.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    .... 9904.411-50 Section 9904.411-50 Federal Acquisition Regulations System COST ACCOUNTING STANDARDS BOARD... ACCOUNTING STANDARDS COST ACCOUNTING STANDARDS 9904.411-50 Techniques for application. (a) Material cost...) The method of computation used for any inventory costing method selected pursuant to the provisions...

  16. Applications of nuclear and isotopic techniques in Indonesia

    SciTech Connect

    Hilmy, N.; Hendranto, K.

    1994-12-31

    Applications of Nuclear and Isotopic Techniques have been developed by the National Atomic Energy Agency (BATAN) since early 1970 in Indonesia. The scope of these applications covers various fields such as agriculture, hydrology, sedimentology and industry. Some applications of tracer techniques in industry which have been done such as measurement of homogeneity of mixing process in fertiliser and paper factory, residence time distribution in gold processing plant, mercury inventory in caustic soda plant, enhanced oil recovery in oil production wells, leakage investigation in dust chamber of fertiliser plant and blockage of pipeline, are presented in this paper. In the field of NDT by radiographic technique, BATAN regularly conducts training courses and also issues licences for Level I and II. Some applications of nuclear techniques in agriculture such as mutation breeding, animal production and animal health have shown the potential of radiation in creating variability as a basis for varietal improvements in several food crop species, the potential of using isotopes as tracers in the studies on metabolism, particularly in relation to the efficiency of rumen fermentative digestion and biological evaluation of locally available feedstuffs from agricultural and agro-industrial byproducts. So far, four varieties of nice, two varieties of soybean, and one variety of mungbean have been officially approved for release, and one formulation of feed supplement utilizing locally available agricultural and agro-industrial byproducts has been established and used for cattle and goats. In animal health, a radiovaccine against coccidiosis in poultry has been produced and used routinely.

  17. Comparison of turbulent-flow chromatography with automated solid-phase extraction in 96-well plates and liquid-liquid extraction used as plasma sample preparation techniques for liquid chromatography-tandem mass spectrometry.

    PubMed

    Zimmer, D; Pickard, V; Czembor, W; Müller, C

    1999-08-27

    Turbulent flow chromatography (TFC) combined with the high selectivity and sensitivity of tandem mass spectrometry (MS-MS) is a new technique for the fast direct analysis of drugs from crude plasma. TFC in the 96-well plate format reduces significantly the time required for sample clean-up in the laboratory. For example, for 100 samples the workload for a technician is reduced from about 8 h by a manual liquid-liquid extraction (LLE) assay to about 1 h in the case of TFC. Sample clean-up and analysis are performed on-line on the same column. Similar chromatographic performance and validation results were achieved using HTLC Turbo-C18 columns (Cohesive Technologies) and Oasis HLB extraction columns (Waters). One 96-well plate with 96 plasma samples is analyzed within 5.25 h, corresponding to 3.3 min per sample. Compared to this LLE and analysis of 96 samples takes about 16 h. Two structurally different and highly protein bound compounds, drug A and drug B, were analyzed under identical TFC conditions and the assays were fully validated for the application to toxicokinetics studies (compliant with Good Laboratory Practices-GLP). The limit of quantitation was 1.00 microg/l and the linear working range covered three orders of magnitude for both drugs. In the case of drug A the quality of analysis by TFC was similar to the reference LLE assay and slightly better than automated solid-phase extraction in 96-well plates. The accuracy was -3.1 to 6.7% and the precision was 3.1 to 6.8% in the case of drug A determined for dog plasma by TFC-MS-MS. For drug B the accuracy was -3.7 to 3.5% and the precision was 1.6 to 5.4% for rat plasma, which is even slightly better than what was achieved with the validated protein precipitation assay.

  18. Applications of ion chromatography with electrospray mass spectrometric detection to the determination of environmental contaminants in water.

    PubMed

    Roehl, R; Slingsby, R; Avdalovic, N; Jackson, P E

    2002-05-17

    Ion chromatography (IC) is widely used for the compliance monitoring of common inorganic anions in drinking water. However, there has recently been considerable interest in the development of IC methods to meet regulatory requirements for analytes other than common inorganic anions, including disinfection byproduct anions, perchlorate, and haloacetic acids. Many of these new methods require the use of large injection volumes, high capacity columns and analyte specific detection schemes, such as inductively coupled plasma mass spectrometry or postcolumn reaction with UV-Vis detection, in order to meet current regulatory objectives. Electrospray ionization mass spectrometry (ESI-MS) is a detection technique that is particularly suitable for the analysis of permanently ionized or polar, ionizable compounds. The combination of IC with MS detection is emerging as an important tool for the analysis of ionic compounds in drinking water, as it provides increased specificity and sensitivity compared to conductivity detection. This paper reports on the application of IC-ESI-MS for the confirmation and quantitation of environmentally significant contaminants, i.e. compounds with adverse health effects which are either regulated or being considered for regulation, such as bromate, perchlorate, haloacetic acids, and selenium species, in various water samples.

  19. Improvements and application of a modified gas chromatography atomic fluorescence spectroscopy method for routine determination of methylmercury in biota samples.

    PubMed

    Gorecki, Jerzy; Díez, Sergi; Macherzynski, Mariusz; Kalisinska, Elżbieta; Golas, Janusz

    2013-10-15

    Improvements to the application of a combined solid-phase microextraction followed by gas chromatography coupled to pyrolysis and atomic fluorescence spectrometry method (SPME-GC-AFS) for methylmercury (MeHg) determination in biota samples are presented. Our new method includes improvements in the methodology of determination and the quantification technique. A shaker instead of a stirrer was used, in order to reduce the possibility of sample contamination and to simplify cleaning procedures. Then, optimal rotation frequency and shaking time were settled at 800 rpm and 10 min, respectively. Moreover, the GC-AFS system was equipped with a valve and an argon heater to eliminate the effect of the decrease in analytical signal caused by the moisture released from SPME fiber. For its determination, MeHg was first extracted from biota samples with a 25% KOH solution (3h) and then it was quantified by two methods, a conventional double standard addition method (AC) and a modified matrix-matched calibration (MQ) which is two times faster than the AC method. Both procedures were successfully tested with certified reference materials, and applied for the first time to the determination of MeHg in muscle samples of goosander (Mergus merganser) and liver samples of white-tailed eagle (Haliaeetus albicilla) with values ranging from 1.19 to 3.84 mg/kg dry weight (dw), and from 0.69 to 6.23 mg kg(-1) dw, respectively.

  20. Application of Molecular Diagnostic Techniques for Viral Testing

    PubMed Central

    Cobo, Fernando

    2012-01-01

    Nucleic acid amplification techniques are commonly used currently to diagnose viral diseases and manage patients with this kind of illnesses. These techniques have had a rapid but unconventional route of development during the last 30 years, with the discovery and introduction of several assays in clinical diagnosis. The increase in the number of commercially available methods has facilitated the use of this technology in the majority of laboratories worldwide. This technology has reduced the use of some other techniques such as viral culture based methods and serological assays in the clinical virology laboratory. Moreover, nucleic acid amplification techniques are now the methods of reference and also the most useful assays for the diagnosis in several diseases. The introduction of these techniques and their automation provides new opportunities for the clinical laboratory to affect patient care. The main objectives in performing nucleic acid tests in this field are to provide timely results useful for high-quality patient care at a reasonable cost, because rapid results are associated with improvements in patients care. The use of amplification techniques such as polymerase chain reaction, real-time polymerase chain reaction or nucleic acid sequence-based amplification for virus detection, genotyping and quantification have some advantages like high sensitivity and reproducibility, as well as a broad dynamic range. This review is an up-to-date of the main nucleic acid techniques and their clinical applications, and special challenges and opportunities that these techniques currently provide for the clinical virology laboratory. PMID:23248732

  1. Application of optical correlation techniques to particle imaging velocimetry

    NASA Technical Reports Server (NTRS)

    Wernet, Mark P.; Edwards, Robert V.

    1988-01-01

    Pulsed laser sheet velocimetry yields nonintrusive measurements of velocity vectors across an extended 2-dimensional region of the flow field. The application of optical correlation techniques to the analysis of multiple exposure laser light sheet photographs can reduce and/or simplify the data reduction time and hardware. Here, Matched Spatial Filters (MSF) are used in a pattern recognition system. Usually MSFs are used to identify the assembly line parts. In this application, the MSFs are used to identify the iso-velocity vector contours in the flow. The patterns to be recognized are the recorded particle images in a pulsed laser light sheet photograph. Measurement of the direction of the partical image displacements between exposures yields the velocity vector. The particle image exposure sequence is designed such that the velocity vector direction is determined unambiguously. A global analysis technique is used in comparison to the more common particle tracking algorithms and Young's fringe analysis technique.

  2. Toner and paper-based fabrication techniques for microfluidic applications.

    PubMed

    Coltro, Wendell Karlos Tomazelli; de Jesus, Dosil Pereira; da Silva, José Alberto Fracassi; do Lago, Claudimir Lucio; Carrilho, Emanuel

    2010-08-01

    The interest in low-cost microfluidic platforms as well as emerging microfabrication techniques has increased considerably over the last years. Toner- and paper-based techniques have appeared as two of the most promising platforms for the production of disposable devices for on-chip applications. This review focuses on recent advances in the fabrication techniques and in the analytical/bioanalytical applications of toner and paper-based devices. The discussion is divided in two parts dealing with (i) toner and (ii) paper devices. Examples of miniaturized devices fabricated by using direct-printing or toner transfer masking in polyester-toner, glass, PDMS as well as conductive platforms as recordable compact disks and printed circuit board are presented. The construction and the use of paper-based devices for off-site diagnosis and bioassays are also described to cover this emerging platform for low-cost diagnostics.

  3. Usability evaluation techniques in mobile commerce applications: A systematic review

    NASA Astrophysics Data System (ADS)

    Hussain, Azham; Mkpojiogu, Emmanuel O. C.

    2016-08-01

    Obviously, there are a number of literatures concerning the usability of mobile commerce (m-commerce) applications and related areas, but they do not adequately provide knowledge about usability techniques used in most of the empirical usability evaluation for m-commerce application. Therefore, this paper is aimed at producing the usability techniques frequently used in the aspect of usability evaluation for m-commerce applications. To achieve the stated objective, systematic literature review was employed. Sixty seven papers were downloaded in usability evaluation for m-commerce and related areas; twenty one most relevant studies were selected for review in order to extract the appropriate information. The results from the review shows that heuristic evaluation, formal test and think aloud methods are the most commonly used methods in m-commerce application in comparison to cognitive walkthrough and the informal test methods. Moreover, most of the studies applied control experiment (33.3% of the total studies); other studies that applied case study for usability evaluation are 14.28%. The results from this paper provide additional knowledge to the usability practitioners and research community for the current state and use of usability techniques in m-commerce application.

  4. Quantification of levoglucosan and its isomers by High Performance Liquid Chromatography - Electrospray Ionization tandem Mass Spectrometry and its applications to atmospheric and soil samples

    NASA Astrophysics Data System (ADS)

    Piot, C.; Jaffrezo, J.-L.; Cozic, J.; Pissot, N.; El Haddad, I.; Marchand, N.; Besombes, J.-L.

    2011-07-01

    The determination of atmospheric concentrations of levoglucosan and its two isomers, unambiguous tracers of biomass burning emissions, became even more important with the development of wood as renewable energy for domestic heating. Many researches demonstrated the increase during recent years of atmospheric particulate matter load due to domestic biomass combustion in developed countries. Analysis of biomass burning tracers is traditionally performed with Gas Chromatography-Mass Spectrometry (GC-MS) technique after derivatization and requires an organic solvent extraction. A simpler and faster technique using Liquid Chromatography - Electrospray Ionisation - tandem Mass Spectrometry (LC-ESI-MS/MS) was optimized for the analysis of levoglucosan, mannosan and galactosan isomers after an aqueous extraction. This technique allows a good separation between the three compounds in a very reduced time (runtime ~5 min). LOD and LOQ of this method are 30 μg l-1 and 100 μg l-1 respectively, allowing the use of filters from low-volume sampler (as commonly used in routine campaigns). A comparison of simultaneous levoglucosan measurements by GC-MS and LC-ESI-MS/MS for about 50 samples coming from different types of sampling sites and seasons was realized and shows very good agreement between the two methods. Therefore LC-ESI-MS/MS method can be used as an alternative to GC-MS particularly for measurement campaigns in routine where analysis time is important and detection limit is reduced. This paper shows that this method is also applicable to other environmental sample types like soil.

  5. Quantification of levoglucosan and its isomers by High Performance Liquid Chromatography - Electrospray Ionization tandem Mass Spectrometry and its applications to atmospheric and soil samples

    NASA Astrophysics Data System (ADS)

    Piot, C.; Jaffrezo, J.-L.; Cozic, J.; Pissot, N.; El Haddad, I.; Marchand, N.; Besombes, J.-L.

    2012-01-01

    The determination of atmospheric concentrations of levoglucosan and its two isomers, unambiguous tracers of biomass burning emissions, became even more important with the development of wood as renewable energy for domestic heating. Many researches demonstrated the increase during recent years of atmospheric particulate matter load due to domestic biomass combustion in developed countries. Analysis of biomass burning tracers is traditionally performed with Gas Chromatography-Mass Spectrometry (GC-MS) technique after derivatization and requires an organic solvent extraction. A simpler and faster technique using Liquid Chromatography - Electrospray Ionisation - tandem Mass Spectrometry (LC-ESI-MS/MS) was optimized for the analysis of levoglucosan, mannosan and galactosan isomers after an aqueous extraction. This technique allows a good separation between the three compounds in a very reduced time (runtime ~5 min). LOD and LOQ of this method are 30 μg l-1 and 100 μg l-1 respectively, allowing the use of filters from low-volume sampler (as commonly used in routine campaigns). A comparison of simultaneous levoglucosan measurements by GC-MS and LC-ESI-MS/MS for about 50 samples coming from different types of sampling sites and seasons was realized and shows very good agreement between the two methods. Therefore LC-ESI-MS/MS method can be used as an alternative to GC-MS particularly for measurement campaigns in routine where analysis time is important and detection limit is reduced. This paper shows that this method is also applicable to other environmental sample types like soil.

  6. A High Performance Image Data Compression Technique for Space Applications

    NASA Technical Reports Server (NTRS)

    Yeh, Pen-Shu; Venbrux, Jack

    2003-01-01

    A highly performing image data compression technique is currently being developed for space science applications under the requirement of high-speed and pushbroom scanning. The technique is also applicable to frame based imaging data. The algorithm combines a two-dimensional transform with a bitplane encoding; this results in an embedded bit string with exact desirable compression rate specified by the user. The compression scheme performs well on a suite of test images acquired from spacecraft instruments. It can also be applied to three-dimensional data cube resulting from hyper-spectral imaging instrument. Flight qualifiable hardware implementations are in development. The implementation is being designed to compress data in excess of 20 Msampledsec and support quantization from 2 to 16 bits. This paper presents the algorithm, its applications and status of development.

  7. Improved esthetic results with fine-tip Dermabond application technique.

    PubMed

    Santibanez-Gallerani, Alberto; Armstrong, Milton B; Thaller, Seth R

    2004-09-01

    Tissue glues and adhesives have achieved increasing popularity as alternatives to small wound closure. When applying these substances, it is often difficult to avoid contact with the surrounding skin and foreign objects such as surgical gloves. A technique for the application of Dermabond is described in this report. Twenty wounds less than 10 cm in length were reapproximated using a fine-tip tuberculin syringe applicator. The wounds were evaluated immediately after the application, and 2, 4, and 6 weeks after surgery. Use of the tuberculin fine-tip technique allowed reapproximation of the wound edges with no clinical evidence of surrounding tissue damage. There were no apparent decreases in wound strength or associated discoloration or fuzziness onto the skin. Esthetic results were considered good to excellent by patients. Dermabond can be accurately applied with a tuberculin syringe, avoiding the surrounding tissue damage and foreign object adhesion reported in the literature.

  8. The application and results of a new flight test technique

    NASA Technical Reports Server (NTRS)

    Duke, E. L.; Lux, D. P.

    1983-01-01

    The application of a flight test maneuver auto-pilot test technique for collecting aerodynamic and structural flight research data on a highly maneuverable aircraft is described. This newly developed flight test technique was applied at the Dryden Flight Research Facility of the NASA Ames Research Center on the highly maneuverable aircraft technology (HiMAT) vehicle. A primary flight experiment was done to verify the design techniques used to develop the HiMAT aerodynamics and structures. This required the collection of large quantities of high-quality pressure distribution, loads, and deflection data. The effectiveness of the flight test technique is illustrated with a flight test example comparing various pressure distribution measurements.

  9. The application and results of a new flight test technique

    NASA Technical Reports Server (NTRS)

    Duke, E. L.; Lux, D. P.

    1983-01-01

    The application of a flight test maneuver auto-pilot test technique for collecting aerodynamic and structural flight research data on a highly maneuverable aircraft is described. This newly developed flight test technique was applied at the Dryden Flight Research Facility of the NASA Ames Research Center on the highly maneuverable aircraft technology (HiMAT) vehicle. A primary flight experiment was done to verify the design techniques used to develop the HiMAT aerodynamics and structures. This required the collection of large quantities of high-quality pressure distribution, loads, and deflection data. The effectiveness of the flight test technique is illustrated with a flight test example comparing various pressure distribution measurements.

  10. Review: Current applications and challenges for liquid chromatography coupled to isotope ratio mass spectrometry (LC/IRMS).

    PubMed

    Godin, Jean-Philippe; McCullagh, James S O

    2011-10-30

    High-precision isotope analysis is recognized as an essential research tool in many fields of study. Until recently, continuous flow isotope ratio mass spectrometry (CF-IRMS) was available via an elemental analyzer or a gas chromatography inlet system for compound-specific analysis of light stable isotopes. In 2004, however, an interface that coupled liquid chromatography with IRMS (LC/IRMS) became commercially available for the first time. This brought the capability for new areas of application, in particular enabling compound-specific δ(13)C analysis of non-volatile, aqueous soluble, compounds from complex mixtures. The interface design brought with it several analytical constraints, however, in particular a lack of compatibility with certain types of chromatography as well as limited flow rates and mobile phase compositions. Routine LC/IRMS methods have, however, been established for measuring the δ(13)C isotopic ratios of underivatized individual compounds for application in archeology, nutrition and physiology, geochemistry, hydrology, soil science and food authenticity. Seven years after its introduction, we review the technical advances and constraints, methodological developments and new applications of liquid chromatography coupled to isotope ratio mass spectrometry.

  11. Fun with Paper Chromatography.

    ERIC Educational Resources Information Center

    Coleman, Dava; Hounshell, Paul B.

    1982-01-01

    Discusses paper chromatographic techniques and provides examples of typical classroom activities. Includes description of retardation values obtained during chromatography exercises and suggests using them for math lessons. (JN)

  12. Enantioresolution in electrokinetic chromatography-complete filling technique using sulfated gamma-cyclodextrin. Software-free topological anticipation.

    PubMed

    Escuder-Gilabert, Laura; Martín-Biosca, Yolanda; Medina-Hernández, María José; Sagrado, Salvador

    2016-10-07

    Few papers have tried to predict the resolution ability of chiral selectors in capillary electrophoresis for the separation of the enantiomers of chiral compounds. In a previous work, we have used molecular information available on-line to establish enantioresolution levels of basic compounds using highly sulfated β-CD (HS-β-CD) as chiral selector in electrokinetic chromatography-complete filling technique (EKC-CFT). The present study is a continuation of this previous work, introducing some novelties. In this work, the ability of sulfated γ-cyclodextrin (S-γ-CD) as chiral selector in EKC-CFT is modelled for the first time. Thirty-three structurally unrelated cationic and neutral compounds (drugs and pesticides) are studied. Categorical enantioresolution levels (RsC, 0 or 1) are assigned from experimental enantioresolution values obtained at different S-γ-CD concentrations. Novel topological parameters connected to the chiral carbon (C(*)-parameters) are introduced. Four C(*)-parameters and a topological parameter of the whole molecule (aromatic atom count) are the most important variables according to a discriminant partial least squares-variable selection process. It suggests the preponderance of the topology adjacent to the chiral carbon to anticipate the RsC levels. A software-free anticipation protocol for new molecules is proposed. Over the current set of molecules evaluated, 100% of correct anticipations (resolved and non-resolved compounds) are obtained, while anticipation of some compounds remains undetermined. A criterion is introduced to alert on compounds which should not be anticipated.

  13. [Determination of 10 sedative-hypnotics in human plasma using pulse splitless injection technique and gas chromatography-mass spectrometry].

    PubMed

    Chang, Qing; Ma, Hongying; Wang, Fangjie; Ou, Honglian; Zou, Ming

    2011-11-01

    A simple, precise and sensitive gas chromatography-mass spectrometry (GC-MS) method coupled with pulse splitless injection technique was developed for the determination of 10 sedative-hypnotics (barbital, amobarbital, phenobarbital, oxazepam, diazepam, nitrazepam, clonazepam, estazolam, alprazolam, triazolam) in human plasma. The drugs spiked in plasma were extracted with ethyl acetate after alkalization with 0.1 mol/L NaOH solution. The organic solvent was evaporated under nitrogen stream, and the residues were redissolved by ethyl acetate. The separation was performed on an HP-5MS column (30 m x 250 microm x 0.25 microm). The analytes were determined and identified using selected ion monitoring (SIM) mode and scan mode, respectively. The internal standard method was used for the determination. The target analytes were well separated from each other on their SIM chromatograms and also on the total ion current (TIC) chromatograms. The blank extract from human plasma gave no peaks that interfered with all the analytes on the chromatogram. The calibration curves for 10 sedative-hypnotics showed excellent linearity. The correlation coefficients of all the drugs were higher than 0.9954. The recoveries of the drugs spiked in human plasma ranged from 92.28% to 111.7%, and the relative standard deviations (RSDs) of intra-day and inter-day determinations were from 4.09% to 14.26%. The detection limits ranged from 2 to 20 microg/L. The method is simple, reliable, rapid and sensitive for the determination and the quantification of 10 sedative-hypnotics in human plasma and seems to be useful in the practice of clinical toxicological cases.

  14. Application of AI techniques to blast furnace operations

    SciTech Connect

    Iida, Osamu; Ushijima, Yuichi; Sawada, Toshiro

    1995-10-01

    It was during the first stages of application of artificial intelligence (AI) to industrial fields, that the ironmaking division of Mizushima works at Kawasaki Steel recognized its potential. Since that time, the division has sought applications for these techniques to solve various problems. AI techniques applied to control the No. 3 blast furnace operations at the Mizushima works include: Blast furnace control by a diagnostic type of expert system that gives guidance to the actions required for blast furnace operation as well as control of furnace heat by automatically setting blast temperature; Hot stove combustion control by a combination of fuzzy inference and a physical model to insure good thermal efficiency of the stove; and blast furnace burden control using neural networks makes it possible to connect the pattern of gas flow distribution with the condition of the furnace. Experience of AI to control the blast furnace and other ironmaking operations has proved its capability for achieving automation and increased operating efficiency. The benefits are very high. For these reasons, the applications of AI techniques will be extended in the future and new techniques studied to further improve the power of AI.

  15. The applications of streamtube techniques to full field waterflood simulations

    SciTech Connect

    Emanuel, A.S.; Milliken, W.J.

    1995-12-31

    A comparison between streamtube and finite-difference modeling for multiwell waterfloods is presented to show the utility of streamtubes as a reservoir modeling technique. The streamtube formulation follows most of the classical techniques presented in the literature. Areal sweep in the model is determined by streamtubes developed on the basis of unit mobility ratio and corrected for changing mobility ratio by the method of Martin and Wegner. Displacement in the streamtubes is calculated by a Welge construction with vertical heterogeneity represented by Dykstra-Parsons layering. This work differs from previous efforts in that the streamtube patterns are changed to reflect changes in well development and that wells are individually history matched by assignment of Dykstra-Parsons coefficients on a well-by-well basis. Two applications of the technique are described. The first is a comparison between finite-difference and streamtube model history match and prediction for a waterflood based on the Ninth SPE Comparative Solution Project. This application is designed to display the basis of the streamtube technique in the context of a standardized industry problem. The second application is for a recently completed study of the Kaybob North reservoir which shows model development and history matching of a 100+ well field with a 30-year history and a number of realignments.

  16. The application of rapid prototyping technique in chin augmentation.

    PubMed

    Li, Min; Lin, Xin; Xu, Yongchen

    2010-04-01

    This article discusses the application of computer-aided design and rapid prototyping techniques in prosthetic chin augmentation for mild microgenia. Nine cases of mild microgenia underwent an electrobeam computer tomography scan. Then we performed three-dimensional reconstruction and operative design using computer software. According to the design, we determined the shape and size of the prostheses and made an individualized prosthesis for each chin augmentation with the rapid prototyping technique. With the application of computer-aided design and a rapid prototyping technique, we could determine the shape, size, and embedding location accurately. Prefabricating the individual prosthesis model is useful in improving the accuracy of treatment. In the nine cases of mild microgenia, three received a silicone implant, four received an ePTFE implant, and two received a Medpor implant. All patients were satisfied with the results. During follow-up at 6-12 months, all patients remained satisfied. The application of computer-aided design and rapid prototyping techniques can offer surgeons the ability to design an individualized ideal prosthesis for each patient.

  17. Green chromatography.

    PubMed

    Płotka, Justyna; Tobiszewski, Marek; Sulej, Anna Maria; Kupska, Magdalena; Górecki, Tadeusz; Namieśnik, Jacek

    2013-09-13

    Analysis of organic compounds in samples characterized by different composition of the matrix is very important in many areas. A vast majority of organic compound determinations are performed using gas or liquid chromatographic methods. It is thus very important that these methods have negligible environmental impact. Chromatographic techniques have the potential to be greener at all steps of the analysis, from sample collection and preparation to separation and final determination. The paper summarizes the approaches used to accomplish the goals of green chromatography. While complete elimination of sample preparation would be an ideal approach, it is not always practical. Solventless extraction techniques offer a very good alternative. Where solvents must be used, the focus should be on the minimization of their consumption. The approaches used to make chromatographic separations greener differ depending on the type of chromatography. In gas chromatography it is advisable to move away from using helium as the carrier gas because it is a non-renewable resource. GC separations using low thermal mass technology can be greener because of energy savings offered by this technology. In liquid chromatography the focus should be on the reduction of solvent consumption and replacement of toxic and environmentally hazardous solvents with more benign alternatives. Multidimensional separation techniques have the potential to make the analysis greener in both GC and LC. The environmental impact of the method is often determined by the location of the instrument with respect to the sample collection point. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Application of optimization techniques to vehicle design: A review

    NASA Technical Reports Server (NTRS)

    Prasad, B.; Magee, C. L.

    1984-01-01

    The work that has been done in the last decade or so in the application of optimization techniques to vehicle design is discussed. Much of the work reviewed deals with the design of body or suspension (chassis) components for reduced weight. Also reviewed are studies dealing with system optimization problems for improved functional performance, such as ride or handling. In reviewing the work on the use of optimization techniques, one notes the transition from the rare mention of the methods in the 70's to an increased effort in the early 80's. Efficient and convenient optimization and analysis tools still need to be developed so that they can be regularly applied in the early design stage of the vehicle development cycle to be most effective. Based on the reported applications, an attempt is made to assess the potential for automotive application of optimization techniques. The major issue involved remains the creation of quantifiable means of analysis to be used in vehicle design. The conventional process of vehicle design still contains much experience-based input because it has not yet proven possible to quantify all important constraints. This restraint on the part of the analysis will continue to be a major limiting factor in application of optimization to vehicle design.

  19. [Clinical applications of arterial spin labeling technique in brain diseases].

    PubMed

    Wang, Li; Zheng, Gang; Zhao, Tiezhu; Guo, Chao; Li, Lin; Lu, Guangming

    2013-02-01

    Arterial spin labeling (ASL) technique is a kind of perfusion functional magnetic resonance imaging method that is based on endogenous contrast, and it can measure cerebral blood flow (CBF) noninvasively. The ASL technique has advantages of noninvasiveness, simplicity and relatively lower costs so that it is more suitable for longitudinal studies compared with previous perfusion methods, such as positron emission tomography (PET), single photon emission computed tomography (SPECT), CT and the contrast agent based magnetic resonance perfusion imaging. This paper mainly discusses the current clinical applications of ASL in brain diseases as cerebrovascular diseases, brain tumors, Alzheimer's disease and epilepsy, etc.

  20. The application of artificial intelligence techniques to large distributed networks

    NASA Technical Reports Server (NTRS)

    Dubyah, R.; Smith, T. R.; Star, J. L.

    1985-01-01

    Data accessibility and transfer of information, including the land resources information system pilot, are structured as large computer information networks. These pilot efforts include the reduction of the difficulty to find and use data, reducing processing costs, and minimize incompatibility between data sources. Artificial Intelligence (AI) techniques were suggested to achieve these goals. The applicability of certain AI techniques are explored in the context of distributed problem solving systems and the pilot land data system (PLDS). The topics discussed include: PLDS and its data processing requirements, expert systems and PLDS, distributed problem solving systems, AI problem solving paradigms, query processing, and distributed data bases.

  1. Application of Nondestructive Testing Techniques to Materials Testing.

    DTIC Science & Technology

    1986-02-01

    7D-Al?2 605 APPLICATION OF NONDESTRUCTIVE TESTING TECHNIQUES To / MATERIALS TESTING(U) STANFORD UNIV CA EDWARD L GINZTON LAB OF PHYSICS G S KIND FEB...U EDWARD L. GINTZON LAB, W.W. HANSEN LAB OF PHYSIC ! 2306/A2 (%J STANFORD CA 94305’ 11 ,. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE Feb 1986...we could improve optical systems by employing modern electronic techniques within the optical system. Our purpose has been to make accurate profile

  2. Mutually supportive use of stable isotope and gas chromatography techniques to understand ecohydrological interactions in dryland environments

    NASA Astrophysics Data System (ADS)

    Puttock, A.; Brazier, R. E.; Dungait, J. A. J.; Bol, R.; Dixon, E. R.; Macleod, C. J. A.

    2012-04-01

    Many drylands globally are experiencing extensive vegetation change. In the semi-arid Southwestern United States, this change is characterised by the encroachment of woody vegetation into environments previously dominated by grassland (Van Auken. 2009). The transition from grass to woody vegetation results in a change in ecosystem structure and function (Turnbull et al. 2008). Structural change is typically characterised by an increased heterogeneity of soil and vegetation resources, associated with reduced vegetation coverage and an increased vulnerability to soil erosion and the potential loss of key nutrients to adjacent fluvial systems. This project uses an ecohydrological approach, monitoring natural rainfall-runoff events and resulting water and sediment fluxes over six bounded plots with different vegetation coverage at the Sevilleta National Wildlife Refuge, New Mexico, USA. The experiment takes advantage of a shift in the photosynthetic pathway of dominant vegetation from C3 piñon-juniper (Pinus edulis-Juniperus monosperma) mixed stand through a C4 pure-grass (Bouteloua eriopoda) to C3 shrub (Larrea tridentate). This allows for the utilisation of natural abundance tracing techniques, specifically stable 13C isotope and gas chromatography lipid biomarker analyses. Results collected during the 2010 and 2011 monsoon seasons will be presented, using biogeochemical signatures, to trace and partition fluvial soil organic matter and carbon fluxes during runoff generating rainfall events. Results show that biogeochemical signatures specific to individual plant species can be used to define the provenance of carbon, quantifying whether more Pinus edulis-Juniperus monosperma derived carbon is mobilised from the upland plots, or whether more Larrea tridentata carbon is lost when compared to bouteloa eripoda losses in the lowlands. Results also show that biogeochemical signatures vary with event characteristics, raising the possibility of using these tracing

  3. Review of optimization techniques of polygeneration systems for building applications

    NASA Astrophysics Data System (ADS)

    Y, Rong A.; Y, Su; R, Lahdelma

    2016-08-01

    Polygeneration means simultaneous production of two or more energy products in a single integrated process. Polygeneration is an energy-efficient technology and plays an important role in transition into future low-carbon energy systems. It can find wide applications in utilities, different types of industrial sectors and building sectors. This paper mainly focus on polygeneration applications in building sectors. The scales of polygeneration systems in building sectors range from the micro-level for a single home building to the large- level for residential districts. Also the development of polygeneration microgrid is related to building applications. The paper aims at giving a comprehensive review for optimization techniques for designing, synthesizing and operating different types of polygeneration systems for building applications.

  4. Preparation, characterization and application of a reversed phase liquid chromatography/hydrophilic interaction chromatography mixed-mode C18-DTT stationary phase.

    PubMed

    Wang, Qing; Long, Yao; Yao, Lin; Xu, Li; Shi, Zhi-Guo; Xu, Lanying

    2016-01-01

    A mixed-mode chromatographic stationary phase, C18-DTT (dithiothreitol) silica (SiO2) was prepared through "thiol-ene" click chemistry. The obtained material was characterized by fourier transform infrared spectroscope, nitrogen adsorption analysis and contact angle analysis. Chromatographic performance of the C18-DTT was systemically evaluated by studying the effect of acetonitrile content, pH, buffer concentration of the mobile phase and column temperature. It was demonstrated that the novel stationary phase possessed reversed phase liquid chromatography (RPLC)/hydrophilic interaction liquid chromatography (HILIC) mixed-mode property. The stop-flow test revealed that C18-DTT exhibited excellent compatibility with 100% aqueous mobile phase. Additionally, the stability and column-to-column reproducibility of the C18-DTT material were satisfactory, with relative standard deviations of retention factor of the tested analytes (verapamil, fenbufen, guanine, tetrandrine and nicotinic acid) in the range of 1.82-3.72% and 0.85-1.93%, respectively. Finally, the application of C18-DTT column was demonstrated in the separation of non-steroidal anti-inflammatory drugs, aromatic carboxylic acids, alkaloids, nucleo-analytes and polycyclic aromatic hydrocarbons. It had great resolving power in the analysis of various compounds in HILIC and RPLC chromatographic conditions and was a promising RPLC/HILIC mixed-mode stationary phase.

  5. A high-speed liquid chromatography/tandem mass spectrometry platform using multiplexed multiple-injection chromatography controlled by single software and its application in discovery ADME screening.

    PubMed

    Zhang, Jun; Vath, Marianne; Ferraro, Cheryl; Li, Ying; Murphy, Keeley; Zvyaga, Tatyana; Weller, Harold; Shou, Wilson

    2013-04-15

    Multiplexed liquid chromatography (LC) coupled with multiple-injection-chromatogram acquisition has emerged as the method of choice for high-speed discovery bioanalysis, because it significantly reduces injection-to-injection cycle time while maintaining the chromatography quality. Historically, systems utilizing this approach had been custom built, and therefore relied on custom software tools to communicate with multiple vendor software for system control, which lacked transferability, flexibility and robustness. In this study, we refined a multiplexed bioanalytical system previously reported, by implementing open-deck auto-sampler manifold and multiple-injection-chromatogram acquisition, all on a commercially available system with single software control. As a result of these improvements, the developed LC/tandem mass spectrometry (MS/MS) method on the system was nearly three times faster than the previous method, while demonstrating comparable analytical accuracy, precision and robustness. This system has been evaluated for in vitro ADME screening assays including metabolic stability, CYP inhibition and Caco-2. The biological data generated on the developed system displayed good correlation with those from the previous LC/MS/MS approaches. The developed platform demonstrated applicability to the in vitro screening assays evaluated and has been successfully implemented to support the high-throughput metabolic stability assay, with a significantly improved bioanalytical throughput, capacity and data turnaround. Copyright © 2013 John Wiley & Sons, Ltd.

  6. Inclusion of a MALDI ion source in the ion chromatography technique: conformational information on polymer and biomolecular ions

    NASA Astrophysics Data System (ADS)

    von Helden, Gert; Wyttenbach, Thomas; Bowers, Michael T.

    1995-08-01

    A matrix-assisted laser desorption ionization (MALDI) source has been coupled to the ion chromatography instrument developed at UCSB. The source produces a strong, consistent signal for several hours on a single sample. In this paper we report the application of this method to a series of poly(ethylene glycol) (PEG) polymers cationized by sodium. Data have been taken for Na+PEG5 to Na+PEG19. The temperature dependence of the ion mobility (collision cross-section) in He gas for Na+PEG9, Na+PEG13 and Na+PEG17 has been measured from 80 to 580 K. A detailed analysis of these three systems has been accomplished in order to extract the conformations of the ion and how they vary with temperature. This analysis included several significant changes from methods used previously. Molecular mechanics methods were used both to obtain the lowest energy 0 K structures and to predict how these structures would change as temperature increases. In order to account for the observed low temperature results, a 12-6-4 potential was incorporated in place of the hard-sphere potential used previously. For all three systems studied in detail, the oxygen atoms on the PEG units solvated the Na+ ion, forming a crown ether type ring of five oxygens surrounding Na+ and several others above and below this ring. The molecular mechanics model was also applied to neutral PEG13. In this instance a quite compact structure is obtained for T <= 200 K but a sudden melting type transition occurs between 200 and 300 K and chaotic motion dominates at and above 300 K. Data are also reported on the temperature dependence of the ion mobility of C60+. This ion is expected to change shape only slightly over the temperature range reported here. Consequently it provided an excellent set of calibration data for evaluating the intramolecular interaction potentials used to describe the collision process.

  7. Extraction chromatography: Progress and opportunities

    SciTech Connect

    Dietz, M.L.; Horwitz, E.P.; Bond, A.H.

    1997-10-01

    Extraction chromatography provides a simple and effective method for the analytical and preparative-scale separation of a variety of metal ions. Recent advances in extractant design, particularly the development of extractants capable of metal ion recognition or of strong complex formation in highly acidic media, have significantly improved the utility of the technique. Advances in support design, most notably the introduction of functionalized supports to enhance metal ion retention, promise to yield further improvements. Column instability remains a significant obstacle, however, to the process-scale application of extraction chromatography. 79 refs.

  8. Advances in dental veneers: materials, applications, and techniques

    PubMed Central

    Pini, Núbia Pavesi; Aguiar, Flávio Henrique Baggio; Lima, Débora Alves Nunes Leite; Lovadino, José Roberto; Terada, Raquel Sano Suga; Pascotto, Renata Corrêa

    2012-01-01

    Laminate veneers are a conservative treatment of unaesthetic anterior teeth. The continued development of dental ceramics offers clinicians many options for creating highly aesthetic and functional porcelain veneers. This evolution of materials, ceramics, and adhesive systems permits improvement of the aesthetic of the smile and the self-esteem of the patient. Clinicians should understand the latest ceramic materials in order to be able to recommend them and their applications and techniques, and to ensure the success of the clinical case. The current literature was reviewed to search for the most important parameters determining the long-term success, correct application, and clinical limitations of porcelain veneers. PMID:23674920

  9. Application of image processing techniques to fluid flow data analysis

    NASA Technical Reports Server (NTRS)

    Giamati, C. C.

    1981-01-01

    The application of color coding techniques used in processing remote sensing imagery to analyze and display fluid flow data is discussed. A minicomputer based color film recording and color CRT display system is described. High quality, high resolution images of two-dimensional data are produced on the film recorder. Three dimensional data, in large volume, are used to generate color motion pictures in which time is used to represent the third dimension. Several applications and examples are presented. System hardware and software is described.

  10. Application of Optimization Techniques to Naval Surface Combatant Ship Synthesis.

    DTIC Science & Technology

    1982-10-01

    ARD-R125 271 APPLICATION OF OPTIMIZATION TECHNIQUES TO NAVAL SURFACE i/I CONBATANT SHIP SYNTHESIS (U) NAVAL POSTGRADUATE SCHOOL MONTEREY CA J L...APPLICATION OF OPTIMIZATION ZECHNIQUES TO NAVAL SURFACE COMBATANT SHIP SYNTHESIS by DTIC JmsL. Jenkins ELECTE MAR 3 1988 a-. October, 1982 Thesis Advisor...Surface Combatant Ship Synthesis Oc ts,-*ob.e .982T uuno I. CONFTU"ACY O N G. R 4 T oumeale t James L. Jenkins I. pOMPUwG’ oneiaolrTei Ni AND A ’ . £IhaIi

  11. Analysis of extractable organic compounds in water by gas chromatography mass spectrometry: applications to surface water.

    PubMed

    Deroux, J M; Gonzalez, C; Le Cloirec, P; Kovacsik, G

    1996-03-01

    Contamination of water by organic pollutants is a common environmental problem. Over a period of 1 year, the surface water of a canal network (Languedoc-Roussillon area, France) was analysed in order to identify organic compounds and to monitor its quality. Pollutants were extracted from 19 l of raw water using methylene chloride in a continuous countercurrent liquid-liquid extractor with a pulsed column. The extraction was performed at a pH above 11 and again at a pH below 2 according to U.S. Environmental Protection Agency method 625. The extract was analysed by gas chromatography/mass spectrometry, using two ionization techniques, namely electron ionization and chemical ionization. Mass spectra obtained by electron ionization were compared with those in a database (NIST). Some natural compounds and micropollutants were identified. Their structures were confirmed by chemical ionization (methane). One hundred and ten substances, making up the broad spectrum of extractable compounds in the surface water studied, were found by this method at a nanogram per litre concentration level. Among them, 13 are priority pollutants. These specific pollutants were qualified.

  12. Literature survey of heat transfer enhancement techniques in refrigeration applications

    SciTech Connect

    Jensen, M.K.; Shome, B.

    1994-05-01

    A survey has been performed of the technical and patent literature on enhanced heat transfer of refrigerants in pool boiling, forced convection evaporation, and condensation. Extensive bibliographies of the technical literature and patents are given. Many passive and active techniques were examined for pure refrigerants, refrigerant-oil mixtures, and refrigerant mixtures. The citations were categorized according to enhancement technique, heat transfer mode, and tube or shell side focus. The effects of the enhancement techniques relative to smooth and/or pure refrigerants were illustrated through the discussion of selected papers. Patented enhancement techniques also are discussed. Enhanced heat transfer has demonstrated significant improvements in performance in many refrigerant applications. However, refrigerant mixtures and refrigerant-oil mixtures have not been studied extensively; no research has been performed with enhanced refrigerant mixtures with oil. Most studies have been of the parametric type; there has been inadequate examination of the fundamental processes governing enhanced refrigerant heat transfer, but some modeling is being done and correlations developed. It is clear that an enhancement technique must be optimized for the refrigerant and operating condition. Fundamental processes governing the heat transfer must be examined if models for enhancement techniques are to be developed; these models could provide the method to optimize a surface. Refrigerant mixtures, with and without oil present, must be studied with enhancement devices; there is too little known to be able to estimate the effects of mixtures (particularly NARMs) with enhanced heat transfer. Other conclusions and recommendations are offered.

  13. Applications notice. [application of space techniques to earth resources, environment management, and space processing

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The discipline programs of the Space and Terrestrial (S&T) Applications Program are described and examples of research areas of current interest are given. Application of space techniques to improve conditions on earth are summarized. Discipline programs discussed include: resource observations; environmental observations; communications; materials processing in space; and applications systems/information systems. Format information on submission of unsolicited proposals for research related to the S&T Applications Program are given.

  14. Application of fisheries-management techniques to assessing impacts

    SciTech Connect

    McKenzie, D.H.; Simmons, M.A.; Skalski, J.R.

    1983-01-01

    Monitoring methods used in fisheries-management assessments were examined and their potential applicability in confirmatory impact monitoring were evaluated using case studies from selected nuclear power plants. A report on Task I of the project examined the application of Catch-Per-Unit-Effort (CPUE) techniques in monitoring programs at riverine, large lake and ocean sites. Included in this final report is an examination of CPUE data for the Oconee Nuclear Plant on Lake Keowee, a reservoir site. This report also presents a summary of results obtained over the life of the project and guidelines for designing and implementing data collection programs and for data analysis and interpretation. Analysis of monitoring data from Lake Keowee confirmed findings from previous analyses of surveys at nuclear power plants on large lakes, rivers and coastal sites. CPUE techniques as applied to these monitoring programs do not provide data necessary to separate changes induced by plant operation from naturally occurring changes.

  15. Application of thermal analysis techniques in activated carbon production

    USGS Publications Warehouse

    Donnals, G.L.; DeBarr, J.A.; Rostam-Abadi, M.; Lizzio, A.A.; Brady, T.A.

    1996-01-01

    Thermal analysis techniques have been used at the ISGS as an aid in the development and characterization of carbon adsorbents. Promising adsorbents from fly ash, tires, and Illinois coals have been produced for various applications. Process conditions determined in the preparation of gram quantities of carbons were used as guides in the preparation of larger samples. TG techniques developed to characterize the carbon adsorbents included the measurement of the kinetics of SO2 adsorption, the performance of rapid proximate analyses, and the determination of equilibrium methane adsorption capacities. Thermal regeneration of carbons was assessed by TG to predict the life cycle of carbon adsorbents in different applications. TPD was used to determine the nature of surface functional groups and their effect on a carbon's adsorption properties.

  16. Overview of the development and application of the hyphenated techniques in nutritional analysis.

    PubMed

    Kotnik, Darja; Smidovnik, Andrej; Jazbec-Križman, Petra; Križman, Mitja; Prošek, Mirko

    2011-06-01

    The development of some sensitive assays for quantitative nutritional analysis with an emphasis on selected hyphenated analytical techniques is reviewed in the present paper. The majority of work is dedicated to reviewing the development of analytical tools for routine analysis of carbohydrates and lipids in biological samples, many of them introduced in our laboratory. Handling biological matrices, where endogenous compounds can mask the analyte of interest or where the occurrence of the coelution effect of several compounds present in different amounts hinders the analyte's peak integration, is a major challenge. To overcome this challenge, hyphenated techniques have become widespread in laboratory practice. Some of these techniques are reviewed, with special attention given to an effective on-line interface for thin-layer chromatography-mass spectrometry and on-line coupling thin-layer chromatography-gas chromatography. Recently introduced an on-line coupling of ion chromatograph and hybrid RF/DC quadrupole-linear ion trap mass spectrometer represent an analytical tool for the solution of bioanalytical problems. Developed methods using ion chromatography-pulsed amperometric detection and ion chromatography-mass spectrometry techniques for the quantitative evaluation of sugars are presented. This paper represents basic contributions of our research work connected with some of modern hyphenated techniques. However, this review is restricted to the published papers to be significant developments or improvements during the last three decades.

  17. Using Aspen to Teach Chromatographic Bioprocessing: A Case Study in Weak Partitioning Chromatography for Biotechnology Applications

    ERIC Educational Resources Information Center

    Evans, Steven T.; Huang, Xinqun; Cramer, Steven M.

    2010-01-01

    The commercial simulator Aspen Chromatography was employed to study and optimize an important new industrial separation process, weak partitioning chromatography. This case study on antibody purification was implemented in a chromatographic separations course. Parametric simulations were performed to investigate the effect of operating parameters…

  18. Using Aspen to Teach Chromatographic Bioprocessing: A Case Study in Weak Partitioning Chromatography for Biotechnology Applications

    ERIC Educational Resources Information Center

    Evans, Steven T.; Huang, Xinqun; Cramer, Steven M.

    2010-01-01

    The commercial simulator Aspen Chromatography was employed to study and optimize an important new industrial separation process, weak partitioning chromatography. This case study on antibody purification was implemented in a chromatographic separations course. Parametric simulations were performed to investigate the effect of operating parameters…

  19. Application of TRIZ Theory in Patternless Casting Manufacturing Technique

    NASA Astrophysics Data System (ADS)

    Yang, Weidong; Gan, Dequan; Jiang, Ping; Tian, Yumei

    The ultimate goal of Patternless Casting Manufacturing (referred to as PCM) is how to obtain the casts by casting the sand mold directly. In the previous PCM, the resin content of sand mold is much higher than that required by traditional resin sand, so the casts obtained are difficult to be sound and qualified products, which limits the application of this technique greatly. In this paper, the TRIZ algorithm is introduced to the innovation process in PCM systematically.

  20. Application of the electrosorption technique to remove Metribuzin pesticide.

    PubMed

    Kitous, O; Cheikh, A; Lounici, H; Grib, H; Pauss, A; Mameri, N

    2009-01-30

    The present work deals with the removal of Metribuzin from aqueous solutions in a batch and continuous mode using electrosorption technique. This technique is based on the combination of two processes: the adsorption of Metribuzin into activated granular carbon (GAC) column and the application of the electrochemical potential. The effects of various experimental parameters (electrochemical potential, volumetric flow rate and initial Metribuzin concentration) on the removal efficiency were investigated. The pesticide sorption capacity at the breakthrough point of the GAC column reached 22 mg(pesticide)g(GAC)(-1). It was increased by more than 100% when the desired electrical potential (-50 mV/SCE) was applied in comparison with the conventional GAC column in similar experimental conditions without electrical potential. Evenmore, the electrosorption technique reduced considerably the drastic decrease encountered when passing from batch mode to continuous column mode.

  1. Analytical techniques of pilot scanning behavior and their application

    NASA Technical Reports Server (NTRS)

    Harris, R. L., Sr.; Glover, B. J.; Spady, A. A., Jr.

    1986-01-01

    The state of the art of oculometric data analysis techniques and their applications in certain research areas such as pilot workload, information transfer provided by various display formats, crew role in automated systems, and pilot training are documented. These analytical techniques produce the following data: real-time viewing of the pilot's scanning behavior, average dwell times, dwell percentages, instrument transition paths, dwell histograms, and entropy rate measures. These types of data are discussed, and overviews of the experimental setup, data analysis techniques, and software are presented. A glossary of terms frequently used in pilot scanning behavior and a bibliography of reports on related research sponsored by NASA Langley Research Center are also presented.

  2. [Application of cell co-culture techniques in medical studies].

    PubMed

    Luo, Yun; Sun, Gui-Bo; Qin, Meng; Yao, Fan; Sun, Xiao-Bo

    2012-11-01

    As the cell co-culture techniques can better imitate an in vivo environment, it is helpful in observing the interactions among cells and between cells and the culture environment, exploring the effect mechanisms of drugs and their possible targets and filling the gaps between the mono-layer cell culture and the whole animal experiments. In recently years, they has attracted much more attention from the medical sector, and thus becoming one of research hotspots in drug research and development and bio-pharmaceutical fields. The cell co-culture techniques, including direct and indirect methods, are mainly used for studying pathological basis, new-type treatment methods and drug activity screening. Existing cell co-culture techniques are used for more pharmacological studies on single drug and less studies on interaction of combined drugs, such as collaborative compatibility and attenuation and synergistic effect among traditional Chinese medicines (TCMs). In line with the action characteristics of multi-component and multi-target, the cell co-culture techniques provide certain reference value for future studies on the effect and mechanism of combined TCMs on organisms as well as new methods for studies on TCMs and their compounds. This essay summarizes cell co-culture methods and their application and look into the future of their application in studies on TCMs and compounds.

  3. Cylindrical millimeter-wave imaging technique and applications

    NASA Astrophysics Data System (ADS)

    Sheen, David M.; McMakin, Douglas L.; Hall, Thomas E.

    2006-05-01

    The wideband microwave or millimeter-wave cylindrical imaging technique has been developed at Pacific Northwest National Laboratory (PNNL) for several applications including concealed weapon detection and automated body measurement for apparel fitting. This technique forms a fully-focused, diffraction-limited, three-dimensional image of the person or imaging target by scanning an inward-directed vertical array around the person or imaging target. The array is switched electronically to sequence across the array at high-speed, so that a full 360 degree mechanical scan over the cylindrical aperture can occur in 2-10 seconds. Wideband, coherent reflection data from each antenna position are recorded in a computer and subsequently reconstructed using an FFT-based image reconstruction algorithm developed at PNNL. The cylindrical scanning configuration is designed to optimize the illumination of the target and minimize non-returns due to specular reflection of the illumination away from the array. In this paper, simulated modeling data are used to explore imaging issues that affect the cylindrical imaging technique. Physical optics scattering simulations are used to model realistic returns from curved surfaces to determine the extent to which specular reflection affects the signal return and subsequent image reconstruction from these surfaces. This is a particularly important issue for the body measurement application. Also, an artifact in the imaging technique, referred to as "circular convolution aliasing" is discussed including methods to reduce or eliminate it. Numerous simulated and laboratory measured imaging results are presented.

  4. Cylindrical Millemeter-Wave Imaging Technique and Applications

    SciTech Connect

    Sheen, David M.; McMakin, Douglas L.; Hall, Thomas E.

    2006-08-01

    The wideband microwave or millimeter-wave cylindrical imaging technique has been developed at Pacific Northwest National Laboratory (PNNL) for several applications including concealed weapon detection and automated body measurements for apparel fitting. This technique forms a fully-focused, diffraction-limited, three-dimensional image of the person or imaging target by scanning an inward-directed vertical array around the person or imaging target. The array is switched electronically to sequence across the array at high-speed, so that a full 360 degree mechanical scan over the cylindrical aperture can occur in 2-10 seconds. Wideband, coherent reflection data from each antenna position are recorded in a computer and subsequently reconstructed using an FFT-based image reconstruction algorithm developed at PNNL. The cylindrical scanning configuration is designed to optimize the illumination of the target and minimize non-returns due to specular reflection of the illumination away from the array. In this paper, simulated modeling data is used to explore imaging issues that affect the cylindrical imaging technique. Physical optics scattering simulations are used to model realistic returns from curved surfaces to determine the extent to which specular reflection affects the signal return and subsequent image reconstruction from these surfaces. This is a particularly important issue for the body measurement application. Also, an artifact in the imaging technique, referred to as "circular convolution aliasing" is discussed including methods to reduce or eliminate it. Numerous simulated and laboratory measured imaging results are presented.

  5. Thin-layer and paper chromatography

    SciTech Connect

    Sherma, J.

    1988-06-15

    This is a selective review of the literature of thin-layer chromatography (TLC) and paper chromatography (PC) cited in Chemical Abstracts from December 2, 1985, to December 14, 1987, and Analytical Abstracts from December 1985 to November 1987. Also searched directly were the following important journals publishing papers on TLC and PC: Journal of Chromatography (including its bibliography issues), Journal of High Resolution Chromography and Chromatography Communications (HRC and CC), Journal of Chromotographic Science, Chromatographia, Analytical Chemistry, JAOAC, and Journal of Liquid Chromatography. Approximately 4300 papers were published in the two-year period on the theory, technique, and applications of TLC. Only a few papers continue to report new work in PC. A high number of TLC papers were published in the Russian, Chinese, Japanese, Polish, and Italian languages, many involving quantification by densitometry. Because these papers are in journals and languages not readily accessible to US scientists, they are in most cases not included in the review.

  6. The 2-D Ion Chromatography Development and Application: Determination of Sulfate in Formation Water at Pre-Salt Region

    NASA Astrophysics Data System (ADS)

    Tonietto, G. B.; Godoy, J. M.; Almeida, A. C.; Mendes, D.; Soluri, D.; Leite, R. S.; Chalom, M. Y.

    2015-12-01

    Formation water is the naturally-occurring water which is contained within the geological formation itself. The quantity and quality of the formation water can both be problematic. Over time, the water volume should decrease as the gas volumes increase. Formation water has been found to contain high levels of Cl, As, Fe, Ba, Mn, PAHs and may even contain naturally occurring radioactive materials. Chlorides in some cases have been found to be in excess of four-five times the level of concentrations found in the ocean. Within the management of well operation, there is sulfate between the analytes of greatest importance due to the potential for hydrogen sulphide formation and consequent corrosion of pipelines. As the concentration of sulfate in these waters can be less than n times that of chloride, a quantitative determination, using the technique of ion chromatography, constitutes an analytical challenge. This work aimed to develop and validate a method for the determination of sulphate ions in hyper-saline waters coming from the oil wells of the pre-salt, using 2D IC. In 2D IC the first column can be understood as a separating column, in which the species with retention times outside a preset range are discarded, while those belonging to this range are retained in a pre-concentrator column to further injecting a second column, the second dimension in which occurs the separation and quantification of the analytes of interest. As the chloride ions have a retention time lower than that of sulfate, a method was developed a for determining sulfate in very low range (mg L-1) by 2D IC, applicable to hypersaline waters, wherein the first dimension is used to the elimination of the matrix, ie, chloride ions, and the second dimension utilized in determining sulfate. For sulphate in a concentration range from 1.00 mg L-1 was obtained an accuracy of 1.0%. The accuracy of the method was tested by the standard addition method different samples of formation water in the pre

  7. Chromatography in Industry

    NASA Astrophysics Data System (ADS)

    Schoenmakers, Peter

    2009-07-01

    This review focuses on the chromatography research that has been carried out within industry or in close cooperation with industry and that has been reported in the scientific literature between 2006 and mid-2008. Companies in the health care sector, such as pharmaceutical and biotechnology companies, are the largest contributors. Industrial research seems to take place in an open environment in cooperation with academia, peer companies, and institutions. Industry appears ready to embrace new technologies as they emerge, but they focus strongly on making chromatography work robustly, reliably, rapidly, and automatically. “Hyphenated” systems that incorporate on-line sample-preparation techniques and mass-spectrometric detection are the rule rather than the exception. Various multidimensional separation methods are finding numerous applications. Strategies aimed at speeding up the development of new chromatographic methods remain the focus of attention. Also, there is a clear trend toward exploring chromatographic methods for parallel processing along with other strategies for high-throughput analysis.

  8. Coupling ultra high-pressure liquid chromatography with mass spectrometry: constraints and possible applications.

    PubMed

    Rodriguez-Aller, Marta; Gurny, Robert; Veuthey, Jean-Luc; Guillarme, Davy

    2013-05-31

    The introduction of columns packed with porous sub-2μm particles and the extension of the upper pressure limit of HPLC instrumentation to 1300bar (ultra-high pressure liquid chromatography, UHPLC) has opened new frontiers in resolution and speed of analysis. However, certain constraints appear when coupling UHPLC technology with mass spectrometry (MS). First, the most significant limitation is related to the narrow peaks that are produced by UHPLC that require a fast duty cycle, which is only available on the latest generations of MS devices. Thus, certain analyzers are more readily compatible with UHPLC (e.g., QqQ or TOF/MS) than others (e.g., ion trap or FT-MS). Second, due to the reduction of the column volume, extra-column band broadening can become significant, leading to a reduction in the kinetic performance of the UHPLC-MS configuration. Third, as the mobile phase linear velocity is higher in UHPLC, the electrospray ionization source must also be able to provide high sensitivity at flow rates of up to 1mL/min. Despite these limitations, the UHPLC-MS/MS platform has successfully been employed over the last decade for various types of applications, including those related to bioanalysis, drug metabolism, multi-residue screening, metabolomics, biopharmaceuticals and polar compounds.

  9. Instrument platforms for thin-layer chromatography.

    PubMed

    Bernard-Savary, Pierre; Poole, Colin F

    2015-11-20

    High performance column and thin-layer chromatography are both instrumental techniques but differ in that column chromatography requires a fully integrated instrument platform with high pressure capability while for thin-layer chromatography separate devices are used for each unit operation, usually at or close to atmospheric pressure, and afford higher flexibility supporting on-line or off-line operation. The unit operations of thin-layer chromatography are defined as sample application, development and evaluation with derivatization as an optional step. The diversity of equipment for each operation contributes to the flexibility of analysis by thin-layer chromatography and supports manual, semi-automated or full-automation of the separation process. Instrument platforms are more than a convenience as they affect performance, repeatability, sample detectability, and time management. The current trend in thin-layer chromatography is to make the unit operations independent of the user so that analysts can perform other tasks while each step is performed. In addition, in thin-layer chromatography it is general practice to separate several samples simultaneously, and instrument platforms are required to accommodate this feature. In this article, we review contemporary instrumentation employed in thin-layer chromatography for sample application, development, derivatization, photodocumentation, densitometric evaluation, and hyphenation with spectroscopic detectors with an emphasis on the variety and performance of commercially available systems. Some suggestions for best practices and avoidance of common mistakes are included. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Virtual 3d City Modeling: Techniques and Applications

    NASA Astrophysics Data System (ADS)

    Singh, S. P.; Jain, K.; Mandla, V. R.

    2013-08-01

    3D city model is a digital representation of the Earth's surface and it's related objects such as Building, Tree, Vegetation, and some manmade feature belonging to urban area. There are various terms used for 3D city models such as "Cybertown", "Cybercity", "Virtual City", or "Digital City". 3D city models are basically a computerized or digital model of a city contains the graphic representation of buildings and other objects in 2.5 or 3D. Generally three main Geomatics approach are using for Virtual 3-D City models generation, in first approach, researcher are using Conventional techniques such as Vector Map data, DEM, Aerial images, second approach are based on High resolution satellite images with LASER scanning, In third method, many researcher are using Terrestrial images by using Close Range Photogrammetry with DSM & Texture mapping. We start this paper from the introduction of various Geomatics techniques for 3D City modeling. These techniques divided in to two main categories: one is based on Automation (Automatic, Semi-automatic and Manual methods), and another is Based on Data input techniques (one is Photogrammetry, another is Laser Techniques). After details study of this, finally in short, we are trying to give the conclusions of this study. In the last, we are trying to give the conclusions of this research paper and also giving a short view for justification and analysis, and present trend for 3D City modeling. This paper gives an overview about the Techniques related with "Generation of Virtual 3-D City models using Geomatics Techniques" and the Applications of Virtual 3D City models. Photogrammetry, (Close range, Aerial, Satellite), Lasergrammetry, GPS, or combination of these modern Geomatics techniques play a major role to create a virtual 3-D City model. Each and every techniques and method has some advantages and some drawbacks. Point cloud model is a modern trend for virtual 3-D city model. Photo-realistic, Scalable, Geo-referenced virtual 3

  11. Non-intrusive measurement techniques for hydroelectric applicants

    SciTech Connect

    Birch, R.; Lemon, D.

    1995-12-31

    Non-intrusive acoustic methods for measuring flows, originally developed for oceanographic applications, are being used in and around hydroelectric dams. The acoustic methods can be categorized as either back-scattering or forward-scattering. The first, using the back-scattered signal, measures the Doppler shift of the returning echo to determine the along-beam component of flow. These instruments are generally called Acoustic Doppler Current Profilers (ADCP). Three beam solutions allow computation of the velocity components. Time gating the return provides a velocity profile with bin segments as small as 0.25 in. In areas of strong magnetic deviation, often the case beside large dams, a gyrocompass can be used to provide directional orientation. The velocity data can also be used to quickly compute river or channel discharge. Typical applications and several case studies are presented. The second acoustic technique is based on a forward-scattering phenomenon known as scintillation. This technique has been used on the Fraser River to monitor flows, and properties of the signal have recently been correlated with the biomass of upstream-migrating salmon. Acoustic scintillation flow measurements are well suited to applications with limited space in the along-flow direction. Applications to hydroelectric dams include turbine intake flow measurements, and a system has been developed to measure flow along fish diversion screens.

  12. MEMS-based power generation techniques for implantable biosensing applications.

    PubMed

    Lueke, Jonathan; Moussa, Walied A

    2011-01-01

    Implantable biosensing is attractive for both medical monitoring and diagnostic applications. It is possible to monitor phenomena such as physical loads on joints or implants, vital signs, or osseointegration in vivo and in real time. Microelectromechanical (MEMS)-based generation techniques can allow for the autonomous operation of implantable biosensors by generating electrical power to replace or supplement existing battery-based power systems. By supplementing existing battery-based power systems for implantable biosensors, the operational lifetime of the sensor is increased. In addition, the potential for a greater amount of available power allows additional components to be added to the biosensing module, such as computational and wireless and components, improving functionality and performance of the biosensor. Photovoltaic, thermovoltaic, micro fuel cell, electrostatic, electromagnetic, and piezoelectric based generation schemes are evaluated in this paper for applicability for implantable biosensing. MEMS-based generation techniques that harvest ambient energy, such as vibration, are much better suited for implantable biosensing applications than fuel-based approaches, producing up to milliwatts of electrical power. High power density MEMS-based approaches, such as piezoelectric and electromagnetic schemes, allow for supplemental and replacement power schemes for biosensing applications to improve device capabilities and performance. In addition, this may allow for the biosensor to be further miniaturized, reducing the need for relatively large batteries with respect to device size. This would cause the implanted biosensor to be less invasive, increasing the quality of care received by the patient.

  13. MEMS-Based Power Generation Techniques for Implantable Biosensing Applications

    PubMed Central

    Lueke, Jonathan; Moussa, Walied A.

    2011-01-01

    Implantable biosensing is attractive for both medical monitoring and diagnostic applications. It is possible to monitor phenomena such as physical loads on joints or implants, vital signs, or osseointegration in vivo and in real time. Microelectromechanical (MEMS)-based generation techniques can allow for the autonomous operation of implantable biosensors by generating electrical power to replace or supplement existing battery-based power systems. By supplementing existing battery-based power systems for implantable biosensors, the operational lifetime of the sensor is increased. In addition, the potential for a greater amount of available power allows additional components to be added to the biosensing module, such as computational and wireless and components, improving functionality and performance of the biosensor. Photovoltaic, thermovoltaic, micro fuel cell, electrostatic, electromagnetic, and piezoelectric based generation schemes are evaluated in this paper for applicability for implantable biosensing. MEMS-based generation techniques that harvest ambient energy, such as vibration, are much better suited for implantable biosensing applications than fuel-based approaches, producing up to milliwatts of electrical power. High power density MEMS-based approaches, such as piezoelectric and electromagnetic schemes, allow for supplemental and replacement power schemes for biosensing applications to improve device capabilities and performance. In addition, this may allow for the biosensor to be further miniaturized, reducing the need for relatively large batteries with respect to device size. This would cause the implanted biosensor to be less invasive, increasing the quality of care received by the patient. PMID:22319362

  14. Modern acoustic emission technique and its application in aviation industry.

    PubMed

    Geng, Rongsheng

    2006-12-22

    This paper proposes the concept of modern acoustic emission (MAE) technique and describes its application in aviation industry. Modern AE is characterized by the combination of AE parameter and waveform analysis based on the understanding of AE source mechanism, the property of sound wave propagation and the interaction between sound wave and the medium in which the sound wave is propagating. Another feature of MAE is characterized by the application of so-called fully digital AE apparatus with low noise, high speed of data transmission and accurate AE source locating capability. MAE is merely an imagination without the realization of the advanced fully digital AE instrument. The application of MAE in monitoring the conditions of aircraft structures during a fatigue test was taken as an example for showing the important role played by AE. Roles of AE in the evaluation of (environment-related) corrosion damage of aircraft were also presented.

  15. Application of split window technique to TIMS data

    NASA Technical Reports Server (NTRS)

    Matsunaga, Tsuneo; Rokugawa, Shuichi; Ishii, Yoshinori

    1992-01-01

    Absorptions by the atmosphere in thermal infrared region are mainly due to water vapor, carbon dioxide, and ozone. As the content of water vapor in the atmosphere greatly changes according to weather conditions, it is important to know its amount between the sensor and the ground for atmospheric corrections of thermal Infrared Multispectral Scanner (TIMS) data (i.e. radiosonde). On the other hand, various atmospheric correction techniques were already developed for sea surface temperature estimations from satellites. Among such techniques, Split Window technique, now widely used for AVHRR (Advanced Very High Resolution Radiometer), uses no radiosonde or any kind of supplementary data but a difference between observed brightness temperatures in two channels for estimating atmospheric effects. Applications of Split Window technique to TIMS data are discussed because availability of atmospheric profile data is not clear when ASTER operates. After these theoretical discussions, the technique is experimentally applied to TIMS data at three ground targets and results are compared with atmospherically corrected data using LOWTRAN 7 with radiosonde data.

  16. Novel one-step headspace dynamic in-syringe liquid phase derivatization-extraction technique for the determination of aqueous aliphatic amines by liquid chromatography with fluorescence detection.

    PubMed

    Muniraj, Sarangapani; Shih, Hou-Kung; Chen, Ying-Fang; Hsiech, Chunming; Ponnusamy, Vinoth Kumar; Jen, Jen-Fon

    2013-06-28

    A novel one-step headspace (HS) dynamic in-syringe (DIS) based liquid-phase derivatization-extraction (LPDE) technique has been developed for the selective determination of two short-chain aliphatic amines (SCAAs) in aqueous samples using high performance liquid chromatography (HPLC) with fluorescence detection (FLD). Methylamine (MA) and dimethylamine (DMA) were selected as model compounds of SCAAs. In this method, a micro-syringe pre-filled with derivatizing reagent solution (9-fluorenylmethyl chloroformate) in the barrel was applied to achieve the simultaneous derivatization and extraction of two methylamines evolved from alkalized aqueous samples through the automated reciprocated movements of syringe plunger. After the derivatization-extraction process, the derivatized phase was directly injected into HPLC-FLD for analysis. Parameters influencing the evolution of methylamines and the HS-DIS-LPDE efficiency, including sample pH and temperature, sampling time, as well as the composition of derivatization reagent, reaction temperature, and frequency of reciprocated plunger movements, were thoroughly examined and optimized. Under optimal conditions, detections were linear in the range of 25-500μgL(-1) for MA and DMA with correlation coefficients all above 0.995. The limits of detection (based on S/N=3) were 5 and 19ngmL(-1) for MA and DMA, respectively. The applicability of the developed method was demonstrated for the determination of MA and DMA in real water samples without any prior cleanup of the sample. The present method provides a simple, selective, automated, low cost and eco-friendly procedure to determine aliphatic amines in aqueous samples.

  17. [Comparison of standard methods for determination of pseudocumene in urine using gas chromatography with the headspace technique and a new method using a headspace automatic sampler].

    PubMed

    Kostrzewski, P; Wiaderna-Brycht, A; Czerski, B

    1996-01-01

    The biological indicators that have been proposed for monitoring occupational exposure are: concentration of the solvent or metabolized compounds in alveolar or expired air samples, in venous or arterial capillary blood samples and in urine samples. Recently, many researches have reported significant relationships between the time-weighted average exposure and the urinary concentrations for various solvents. The aim of our study was to compare two methods in which urinary concentrations of pseudocumene were determined by gas chromatography using headspace technique. The standard method was based on determining concentration of organic solvents in 100 mm3 or 1 cm3 samples of urine. The incubation conditions were as follows: equilibration temperature and time: 70 degrees C, 30 min., respectively. 1 cm3 of gas phase was sampled with a gas-tight syringe and injected into a gas chromatograph. The new method using Headspace Sampler was based on determining concentrations of solvents in 10 cm3 samples of urine. The operating conditions were: equilibration time 30 min.; equlibration temperature 80 degrees C; pressurization time 0.1 min.; loop fill time 0.1 min.; loop equilibration 0.1 min.; loop equilibration time 0.05 min.; inject time 1 min.; loop temperature 150 degrees C, transfer line temperature 150 degrees C. HP 7694 Headspace Sampler minimizes sample degradation with a chemically inert pathway extending from the sample loop to the column head. The analytical parameters of both methods (linearity, precision, reproducibility, stability and sensitivity) are fully compatible with the principles of biological monitoring. Application of the headspace autosampler eliminated interference from the biological matrix and made it possible to achieve very low detection limit.

  18. Separation of single-walled carbon nanotubes by gel-based chromatography using surfactant step-gradient techniques and development of new instrumentation for studying SWCNT reaction processes

    NASA Astrophysics Data System (ADS)

    Breindel, Leonard M.

    Single-walled carbon nanotube (SWCNT) synthesis methods such as CoMoCATTM, HiPcoTM, pulsed laser vaporization (PLV), and catalytic chemical vapor deposition (CCVD) produce several different distributions of (n,m) SWCNT structures, where ( n,m) defines the nanotube diameter and chiral wrapping angle. Post-synthesis processing such as functionalization and/or separations must therefore be employed to yield high purity electronic or single (n,m) samples. Through the use of a surfactant gradient across a gel-based chromatographic column, separations of single (n,m) species can be achieved. Anionic surfactants such as SDS, SDBS, and AOT display different separation effectiveness for single (n,m) species. Results of near-infrared optical absorption for separated SWCNT surfactant suspensions will be discussed, leading to a broader understanding of the important factors necessary for the gel chromatography separation technique. In particular, the effects of SWCNT/surfactant micelle structure are found to be key to achieving fast, simple SWCNT electronic type separations. Additionally, development of new instrumentation for the near-infrared spectrofluorimetric analysis (NIR-SFA) of SWCNTs is useful to the advancement of fundamental SWCNT research and applications. NIR-SFA, for instance, allows for the (n,m) structures of a sample to be identified and monitored during the progress of a chemical reaction or separation experiment. Seeking to achieve the time resolutions necessary for such experiments, the design and optimizations of a system utilizing single-wavelength excitation by diode lasers coupled with a fast NIR detection system are presented.

  19. The Applications and Features of Liquid Chromatography-Mass Spectrometry in the Analysis of Traditional Chinese Medicine

    PubMed Central

    2016-01-01

    With increasingly improved separation of complex samples and detection of unknown material capabilities, liquid chromatography coupled with mass spectrometry (LC-MS) has been widely used in traditional Chinese medicine (TCM) research. This article describes the principles of liquid chromatography (LC) and mass spectrometry (MS) and their advantages and disadvantages in qualitative and quantitative analysis of TCM. We retrieved research literatures about the application of LC-MS in TCM published during the past five years at home and abroad. To better guide the analysis of TCM, this review mainly focuses on the applications category of LC-MS, how often different kinds of LC-MS are used, and the qualitative and quantitative ability of various LC-MS in the study of TCM. PMID:27956918

  20. The Applications and Features of Liquid Chromatography-Mass Spectrometry in the Analysis of Traditional Chinese Medicine.

    PubMed

    Pang, Bingyao; Zhu, Ying; Lu, Longqing; Gu, Fangbing; Chen, Hailong

    2016-01-01

    With increasingly improved separation of complex samples and detection of unknown material capabilities, liquid chromatography coupled with mass spectrometry (LC-MS) has been widely used in traditional Chinese medicine (TCM) research. This article describes the principles of liquid chromatography (LC) and mass spectrometry (MS) and their advantages and disadvantages in qualitative and quantitative analysis of TCM. We retrieved research literatures about the application of LC-MS in TCM published during the past five years at home and abroad. To better guide the analysis of TCM, this review mainly focuses on the applications category of LC-MS, how often different kinds of LC-MS are used, and the qualitative and quantitative ability of various LC-MS in the study of TCM.

  1. Applications of surface analytical techniques in Earth Sciences

    NASA Astrophysics Data System (ADS)

    Qian, Gujie; Li, Yubiao; Gerson, Andrea R.

    2015-03-01

    to show how each technique is applied and used to obtain specific information and to resolve real problems, which forms the central theme of this review. Although this review focuses on applications of these techniques to study mineralogical and geological samples, we also anticipate that researchers from other research areas such as Material and Environmental Sciences may benefit from this review.

  2. Application of Artificial Intelligence Techniques in Unmanned Aerial Vehicle Flight

    NASA Technical Reports Server (NTRS)

    Bauer, Frank H. (Technical Monitor); Dufrene, Warren R., Jr.

    2003-01-01

    This paper describes the development of an application of Artificial Intelligence for Unmanned Aerial Vehicle (UAV) control. The project was done as part of the requirements for a class in Artificial Intelligence (AI) at Nova southeastern University and as an adjunct to a project at NASA Goddard Space Flight Center's Wallops Flight Facility for a resilient, robust, and intelligent UAV flight control system. A method is outlined which allows a base level application for applying an AI method, Fuzzy Logic, to aspects of Control Logic for UAV flight. One element of UAV flight, automated altitude hold, has been implemented and preliminary results displayed. A low cost approach was taken using freeware, gnu, software, and demo programs. The focus of this research has been to outline some of the AI techniques used for UAV flight control and discuss some of the tools used to apply AI techniques. The intent is to succeed with the implementation of applying AI techniques to actually control different aspects of the flight of an UAV.

  3. Ultrasound Elastography: Review of Techniques and Clinical Applications

    PubMed Central

    Sigrist, Rosa M.S.; Liau, Joy; Kaffas, Ahmed El; Chammas, Maria Cristina; Willmann, Juergen K.

    2017-01-01

    Elastography-based imaging techniques have received substantial attention in recent years for non-invasive assessment of tissue mechanical properties. These techniques take advantage of changed soft tissue elasticity in various pathologies to yield qualitative and quantitative information that can be used for diagnostic purposes. Measurements are acquired in specialized imaging modes that can detect tissue stiffness in response to an applied mechanical force (compression or shear wave). Ultrasound-based methods are of particular interest due to its many inherent advantages, such as wide availability including at the bedside and relatively low cost. Several ultrasound elastography techniques using different excitation methods have been developed. In general, these can be classified into strain imaging methods that use internal or external compression stimuli, and shear wave imaging that use ultrasound-generated traveling shear wave stimuli. While ultrasound elastography has shown promising results for non-invasive assessment of liver fibrosis, new applications in breast, thyroid, prostate, kidney and lymph node imaging are emerging. Here, we review the basic principles, foundation physics, and limitations of ultrasound elastography and summarize its current clinical use and ongoing developments in various clinical applications. PMID:28435467

  4. The application of seismic techniques to hydrogeological investigations

    NASA Astrophysics Data System (ADS)

    Jarvis, Kevin Donald Gibson

    The objective of this thesis is to demonstrate some new applications of seismic techniques for hydrogeological applications. A compressional-wave, surface-based, reflection seismic technique is used to map aquifer boundaries within a series of Pleistocene near-surface sediments. The interpretation uses both water wells and sequence stratigraphic concepts to identify the boundaries of new and existing aquifers. The use of the cone penetrometer is an integral part of this thesis. The seismic cone is demonstrated to be both cost-effective and reliable for the acquisition of high-quality vertical seismic profile (VSP) data. Other data from the cone, in particular the tip resistance data, are shown to be an integral link for the conversion of shear-wave velocities to values of hydraulic conductivity. Surface-based, shear-wave reflection seismic data are used to image an aquifer contained within Holocene deltaic sediments. A Bayesian inversion of the shear-wave seismic amplitudes (using cone-derived velocities) results in the generation of a two-dimensional profile of shear-wave velocity that is a direct indication of aquifer heterogeneity. Conversion of the velocity to hydraulic conductivity (using a cone-derived relationship) results in the distribution of a key hydrogeologic property within the aquifer. The results from the thesis show significant promise for improving groundwater flow models and providing new techniques for the management and protection of our groundwater resources.

  5. Local flaps, including pedicled perforator flaps: anatomy, technique, and applications.

    PubMed

    Maciel-Miranda, Alejandro; Morris, Steven F; Hallock, Geoffrey G

    2013-06-01

    After reading this article, the participant should be able to: 1. Discuss the types of local flaps. 2. Analyze the advantages, disadvantages, and applications for each kind of flap. 3. Perform appropriate design and dissection techniques of local flaps. 4. Describe appropriate design and dissection techniques of local perforator and propeller flaps. The purpose of this article is to comprehensively review the topic of local flaps. Local flaps are those that are elevated nearby and then transferred to an adjacent wound. Options include geometric local flaps, axial pattern local flaps and a new exciting group of flaps, local perforator flaps. The principles, advantages, disadvantages, and applications for each are carefully analyzed. Local perforator flaps can be harvested virtually anywhere in the body and represent a significant clinical advance, as these can solve a wide variety of clinical challenges. These flaps do require gentle microsurgical dissection technique with careful handling for inset of the flap and simultaneously provide the same advantages of other types of local flaps because they also use nearby tissues with a similar color match, thickness, and texture, with primary donor-site closure possible. Local perforator flaps are another very useful option that undoubtedly will become more popular as more surgeons become more familiar with their use and advantages.

  6. Application of Artificial Intelligence Techniques in Unmanned Aerial Vehicle Flight

    NASA Technical Reports Server (NTRS)

    Bauer, Frank H. (Technical Monitor); Dufrene, Warren R., Jr.

    2003-01-01

    This paper describes the development of an application of Artificial Intelligence for Unmanned Aerial Vehicle (UAV) control. The project was done as part of the requirements for a class in Artificial Intelligence (AI) at Nova southeastern University and as an adjunct to a project at NASA Goddard Space Flight Center's Wallops Flight Facility for a resilient, robust, and intelligent UAV flight control system. A method is outlined which allows a base level application for applying an AI method, Fuzzy Logic, to aspects of Control Logic for UAV flight. One element of UAV flight, automated altitude hold, has been implemented and preliminary results displayed. A low cost approach was taken using freeware, gnu, software, and demo programs. The focus of this research has been to outline some of the AI techniques used for UAV flight control and discuss some of the tools used to apply AI techniques. The intent is to succeed with the implementation of applying AI techniques to actually control different aspects of the flight of an UAV.

  7. On-line identification of lysergic acid diethylamide (LSD) in tablets using a combination of a sweeping technique and micellar electrokinetic chromatography/77 K fluorescence spectroscopy.

    PubMed

    Fang, Ching; Liu, Ju-Tsung; Lin, Cheng-Huang

    2003-03-01

    This work describes a novel method for the accurate determination of lysergic acid diethylamide (LSD) in tablets. A technique involving sweeping-micellar electrokinetic chromatography (MEKC) was used for the initial on-line concentration and separation, after which a cryogenic molecular fluorescence experiment was performed at 77 K. Using this approach, not only the separation of LSD from the tablet extract was achieved, but on-line spectra were readily distinguishable and could be unambiguously assigned. The results are in agreement with analyses by gas chromatography-mass spectrometry (GC-MS). Thus, this method, which was found to be accurate, sensitive and rapid, has the potential for use as a reliable complementary method to GC-MS in such analyses.

  8. Determination of lysergic acid diethylamide (LSD) in mouse blood by capillary electrophoresis/ fluorescence spectroscopy with sweeping techniques in micellar electrokinetic chromatography.

    PubMed

    Fang, Ching; Liu, Ju-Tsung; Chou, Shiu-Huey; Lin, Cheng-Huang

    2003-03-01

    The separation and on-line concentration of lysergic acid diethylamide (LSD) in mouse blood was achieved by means of capillary electrophoresis/fluorescence spectroscopy using sodium dodecyl sulfate (SDS) as the surfactant. Techniques involving on-line sample concentration, including sweeping micellar electrokinetic chromatography (sweeping-MEKC) and cation-selective exhaustive injection-sweep-micellar electrokinetic chromatography (CSEI-sweep-MEKC) were applied; the optimum on-line concentration and separation conditions were determined. In the analysis of an actual sample, LSD was found in a blood sample from a test mouse (0.1 mg LSD fed to a 20 g mouse; approximately 1/10 to the value of LD(50)). As a result, 120 and 30 ng/mL of LSD was detected at 20 and 60 min, respectively, after ingestion of the doses.

  9. Enantioselective gas chromatography/mass spectrometry of methylsulfonyl PCBs with application to arctic marine mammals.

    PubMed

    Wiberg, K; Letcher, R; Sandau, C; Duffe, J; Norstrom, R; Haglund, P; Bidleman, T

    1998-09-15

    Four different commercially available cyclodextrin (CD) capillary gas chromatography (GC) columns were tested for the enantioselective separation of nine environmentally persistent atropisomeric 3- and 4-methylsulfonyl PCBs (MeSO2-CBs). The selected columns contained cyclodextrins with various cavity diameters (beta- or gamma-CD), which were methylated and/or tert-butyldimethylsilylated (TBDMS) in the 2,3,6-O-positions. The beta-CD column with TBDMS substituents in all of the 2,3,6-O-positions was by far the most selective column for the MeSO2-CBs tested. Enantiomers of congeners with 3-MeSO2 substitution were more easily separated than those with 4-MeSO2 substitution. The separation also seemed to be enhanced for congeners with the chlorine atoms on the non-MeSO2-containing ring and clustered on one side of the same ring. The 2,3-di-O-methyl-6-O-TBDMS-beta-CD was found to give somewhat better selectivity than the corresponding gamma-CD, in comparison between the two columns, which were identical in all other respects. Enantioselective analysis of arctic ringed seal (Phoca hispida) and polar bear (Ursus maritimus) adipose tissue revealed a strong dominance of certain enantiomers. For example, the enantiomer ratio (ER) of 3-MeSO2-CB149 was 0.32 and < 0.1 in ringed seal blubber and polar bear fat, respectively. These low ER values are indicative of highly enantioselective formation, enantioselective metabolism, enantioselective transport across cell membranes, or a combination of the three in both species. Comparable results for the enantiomeric analysis of MeSO2-CBs in biotic tissue extracts were obtained using two highly selective mass spectrometric techniques, ion trap mass spectrometry/mass spectrometry and electron capture negative ion low-resolution mass spectrometry.

  10. Development and Application of Immunoaffinity Chromatography for Coplanar PCBs in Soil and Sediment

    EPA Science Inventory

    An immunoaffinity chromatography (IAC) column was developed as a simple cleanup procedure for preparing environmental samples for analysis of polychlorinated biphenyls (PCBs). Soil and sediment samples were prepared using pressurized liquid extraction (PLE), followed by the IAC c...

  11. Development and Application of Immunoaffinity Chromatography for Coplanar PCBs in Soil and Sediment

    EPA Science Inventory

    An immunoaffinity chromatography (IAC) column was developed as a simple cleanup procedure for preparing environmental samples for analysis of polychlorinated biphenyls (PCBs). Soil and sediment samples were prepared using pressurized liquid extraction (PLE), followed by the IAC c...

  12. Application of seismic-refraction techniques to hydrologic studies

    USGS Publications Warehouse

    Haeni, F.P.

    1988-01-01

    During the past 30 years, seismic-refraction methods have been used extensively in petroleum, mineral, and engineering investigations and to some extent for hydrologic applications. Recent advances in equipment, sound sources, and computer interpretation techniques make seismic refraction a highly effective and economical means of obtaining subsurface data in hydrologic studies. Aquifers that can be defined by one or more high-seismic-velocity surface, such as (1) alluvial or glacial deposits in consolidated rock valleys, (2) limestone or sandstone underlain by metamorphic or igneous rock, or (3) saturated unconsolidated deposits overlain by unsaturated unconsolidated deposits, are ideally suited for seismic-refraction methods. These methods allow economical collection of subsurface data, provide the basis for more efficient collection of data by test drilling or aquifer tests, and result in improved hydrologic studies. This manual briefly reviews the basics of seismic-refraction theory and principles. It emphasizes the use of these techniques in hydrologic investigations and describes the planning, equipment, field procedures, and interpretation techniques needed for this type of study. Further-more, examples of the use of seismic-refraction techniques in a wide variety of hydrologic studies are presented.

  13. Application of seismic-refraction techniques to hydrologic studies

    USGS Publications Warehouse

    Haeni, F.P.

    1986-01-01

    Seismic-refraction methods have been extensively used in petroleum, mineral, and engineering investigations and to some extent, for hydrologic applications during the past 30 years. Recent advances in equipment, sound sources, and computer-interpretation techniques make seismic-refraction methods a highly effective and economical means of obtaining subsurface data in hydrologic studies. Aquifers that can be defined by one or more high seismic-velocity surfaces, such as alluvial or glacial deposits in consolidated rock valleys, limestone or sandstone underlain by metamorphic or igneous rock, or saturated unconsolidated deposits overlain by unsaturated unconsolidated deposits, are ideally suited for applying seismic-refraction methods. These methods allow the economical collection of subsurface data and provide the basis for more efficient collection of subsurface data by test drilling or aquifer tests and results in improved hydrologic studies. This manual briefly reviews the basics of seismic refraction theory and principles. It emphasizes the use of this technique in hydrologic investigations and describes the planning, equipment, field procedures, and interpretation techniques needed for this type of study. Examples of the use of seismic refraction techniques in a wide variety of hydrologic studies are presented. (USGS)

  14. Application of the DREADD technique in biomedical brain research.

    PubMed

    Dobrzanski, Grzegorz; Kossut, Małgorzata

    2017-04-01

    The DREADD (Designer Receptors Exclusively Activated by Designer Drugs) technique is a new chemogenetic approach allowing for selective and remote control of neural activity with a high degree of spatial resolution. Since its discovery in 2007 the DREADD technique was successfully employed into basic research, and together with the optogenetic method provided so far the best tool to influence the activity of the brain circuits and cell populations. The first aim of this review was to concisely describe the technique with regard to such issues like the history of its development, biochemistry as well as modes of the designer receptors delivery and expression. The other aim was to summarize approaches employed for probing of the brain circuits using the DREADD technique and to characterize the current knowledge of the method's application in medical research focusing on two diseases - Parkinson's disease and drug addiction - in which designer receptors were found notably valuable. Copyright © 2016. Published by Elsevier Urban & Partner Sp. z o.o.

  15. Secondary metabolites isolation in natural products chemistry: comparison of two semipreparative chromatographic techniques (high pressure liquid chromatography and high performance thin-layer chromatography).

    PubMed

    Do, Thi Kieu Tiên; Hadji-Minaglou, Francis; Antoniotti, Sylvain; Fernandez, Xavier

    2014-01-17

    Chemical investigations on secondary metabolites in natural products chemistry require efficient isolation techniques for characterization purpose as well as for the evaluation of their biological properties. In the case of phytochemical studies, the performance of the techniques is critical (resolution and yield) since the products generally present a narrow range of polarity and physicochemical properties. Several techniques are currently available, but HPLC (preparative and semipreparative) is the most widely used. To compare the performance of semipreparative HPLC and HPTLC for the isolation of secondary metabolites in different types of extracts, we have chosen carvone from spearmint essential oil (Mentha spicata L.), resveratrol from Fallopia multiflora (Thunb.) Haraldson, and rosmarinic acid from rosemary (Rosmarinus officinalis L.) extracts. The comparison was based on the chromatographic separation, the purity and quantity of isolated compounds, the solvent consumption, the duration and the cost of the isolation operations. The results showed that semipreparative HPTLC can in some case offer some advantages over conventional semipreparative HPLC. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. MR urography in children and adolescents: techniques and clinical applications.

    PubMed

    Dillman, Jonathan R; Trout, Andrew T; Smith, Ethan A

    2016-06-01

    Renal and urinary tract imaging is commonly performed in the pediatric population, particularly in the setting of suspected or known congenital anomalies. In most cases, adequate anatomic assessment can be achieved using ultrasound and fluoroscopic techniques, and evaluation of differential renal function and urinary tract drainage can be accomplished with renal scintigraphy. However, in a subset of children, anatomic or functional questions may remain after this routine evaluation. In this setting, magnetic resonance imaging (MRI) tailored to evaluate the kidneys and urinary tract, known as MR urography (MRU), can be used to depict the kidneys, ureters, and urinary bladder in detail and to determine differential renal function and assess urinary tract drainage. The objectives of this review article are to (1) describe pediatric-specific MRI techniques for assessment of the kidneys and urinary tract and (2) present common clinical applications for pediatric MRU where imaging can "add value" in terms of diagnosis and patient management.

  17. Techniques For Microfabricating Coils For Microelectromechanical Systems Applications

    NASA Astrophysics Data System (ADS)

    Woods, R. C.; Powell, A. L.

    2008-01-01

    The advanced technology necessary for building future space exploration vehicles includes microfabricated coils for making possible self-inductances integrated with other passive and active electronic components. Integrated inductances make possible significant improvements in reliability over the traditional arrangement of using external discrete inductances, as well as allowing significant size (volume) reductions (also important in space vehicles). Two possible fabrication techniques (one using proprietary branded "Foturan" glass, the other using silicon wafer substrates) for microscopic coils are proposed, using electroplating into channels. The techniques have been evaluated for fabricating the planar electrical coils needed for typical microelectromechanical systems applications. There remain problems associated with processing using "Foturan" glass, but coil fabrication on silicon wafers was successful. Fabrication methods such as these are expected to play an important part in the development of systems and subsystems for forthcoming space exploration missions.

  18. Techniques For Microfabricating Coils For Microelectromechanical Systems Applications

    SciTech Connect

    Woods, R. C.; Powell, A. L.

    2008-01-21

    The advanced technology necessary for building future space exploration vehicles includes microfabricated coils for making possible self-inductances integrated with other passive and active electronic components. Integrated inductances make possible significant improvements in reliability over the traditional arrangement of using external discrete inductances, as well as allowing significant size (volume) reductions (also important in space vehicles). Two possible fabrication techniques (one using proprietary branded 'Foturan' glass, the other using silicon wafer substrates) for microscopic coils are proposed, using electroplating into channels. The techniques have been evaluated for fabricating the planar electrical coils needed for typical microelectromechanical systems applications. There remain problems associated with processing using 'Foturan' glass, but coil fabrication on silicon wafers was successful. Fabrication methods such as these are expected to play an important part in the development of systems and subsystems for forthcoming space exploration missions.

  19. Size-exclusion chromatography (HPLC-SEC) technique optimization by simplex method to estimate molecular weight distribution of agave fructans.

    PubMed

    Moreno-Vilet, Lorena; Bostyn, Stéphane; Flores-Montaño, Jose-Luis; Camacho-Ruiz, Rosa-María

    2017-12-15

    Agave fructans are increasingly important in food industry and nutrition sciences as a potential ingredient of functional food, thus practical analysis tools to characterize them are needed. In view of the importance of the molecular weight on the functional properties of agave fructans, this study has the purpose to optimize a method to determine their molecular weight distribution by HPLC-SEC for industrial application. The optimization was carried out using a simplex method. The optimum conditions obtained were at column temperature of 61.7°C using tri-distilled water without salt, adjusted pH of 5.4 and a flow rate of 0.36mL/min. The exclusion range is from 1 to 49 of polymerization degree (180-7966Da). This proposed method represents an accurate and fast alternative to standard methods involving multiple-detection or hydrolysis of fructans. The industrial applications of this technique might be for quality control, study of fractionation processes and determination of purity. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Novel atmospheric extinction measurement techniques for aerospace laser system applications

    NASA Astrophysics Data System (ADS)

    Sabatini, Roberto; Richardson, Mark

    2013-01-01

    Novel techniques for laser beam atmospheric extinction measurements, suitable for manned and unmanned aerospace vehicle applications, are presented in this paper. Extinction measurements are essential to support the engineering development and the operational employment of a variety of aerospace electro-optical sensor systems, allowing calculation of the range performance attainable with such systems in current and likely future applications. Such applications include ranging, weaponry, Earth remote sensing and possible planetary exploration missions performed by satellites and unmanned flight vehicles. Unlike traditional LIDAR methods, the proposed techniques are based on measurements of the laser energy (intensity and spatial distribution) incident on target surfaces of known geometric and reflective characteristics, by means of infrared detectors and/or infrared cameras calibrated for radiance. Various laser sources can be employed with wavelengths from the visible to the far infrared portions of the spectrum, allowing for data correlation and extended sensitivity. Errors affecting measurements performed using the proposed methods are discussed in the paper and algorithms are proposed that allow a direct determination of the atmospheric transmittance and spatial characteristics of the laser spot. These algorithms take into account a variety of linear and non-linear propagation effects. Finally, results are presented relative to some experimental activities performed to validate the proposed techniques. Particularly, data are presented relative to both ground and flight trials performed with laser systems operating in the near infrared (NIR) at λ = 1064 nm and λ = 1550 nm. This includes ground tests performed with 10 Hz and 20 kHz PRF NIR laser systems in a large variety of atmospheric conditions, and flight trials performed with a 10 Hz airborne NIR laser system installed on a TORNADO aircraft, flying up to altitudes of 22,000 ft.

  1. Recent Advances in Seismic Wavefront Tracking Techniques and Their Applications

    NASA Astrophysics Data System (ADS)

    Sambridge, M.; Rawlinson, N.; Hauser, J.

    2007-12-01

    In observational seismology, wavefront tracking techniques are becoming increasingly popular as a means of predicting two point traveltimes and their associated paths. Possible applications include reflection migration, earthquake relocation and seismic tomography at a wide variety of scales. Compared with traditional ray based techniques such as shooting and bending, wavefront tracking has the advantage of locating traveltimes between the source and every point in the medium; in many cases, improved efficiency and robustness; and greater potential for tracking multiple arrivals. In this presentation, two wavefront tracking techniques will be considered: the so-called Fast Marching Method (FMM), and a wavefront construction (WFC) scheme. Over the last several years, FMM has become a mature technique in seismology, with a number of improvements to the underlying theory and the release of software tools that allow it to be used in a variety of applications. At its core, FMM is a grid based solver that implicitly tracks a propagating wavefront by seeking finite difference solutions to the eikonal equation along an evolving narrow band. Recent developments include the use of source grid refinement to improve accuracy, the introduction of a multi-stage scheme to allow reflections and refractions to be tracked in layered media, and extension to spherical coordinates. Implementation of these ideas has led to a number of different applications, including teleseismic tomography, wide-angle reflection and refraction tomography, earthquake relocation, and ambient noise imaging using surface waves. The WFC scheme represents the wavefront surface as a set of points in 6-D phase space; these points are advanced in time using local initial value ray tracing in order to form a sequence of wavefront surfaces that fill the model volume. Surface refinement and simplification techniques inspired by recent developments in computer graphics are used to maintain a fixed density of nodes

  2. Optical and digital microscopic imaging techniques and applications in pathology.

    PubMed

    Chen, Xiaodong; Zheng, Bin; Liu, Hong

    2011-01-01

    The conventional optical microscope has been the primary tool in assisting pathological examinations. The modern digital pathology combines the power of microscopy, electronic detection, and computerized analysis. It enables cellular-, molecular-, and genetic-imaging at high efficiency and accuracy to facilitate clinical screening and diagnosis. This paper first reviews the fundamental concepts of microscopic imaging and introduces the technical features and associated clinical applications of optical microscopes, electron microscopes, scanning tunnel microscopes, and fluorescence microscopes. The interface of microscopy with digital image acquisition methods is discussed. The recent developments and future perspectives of contemporary microscopic imaging techniques such as three-dimensional and in vivo imaging are analyzed for their clinical potentials.

  3. Application of digital image processing techniques to astronomical imagery, 1979

    NASA Technical Reports Server (NTRS)

    Lorre, J. J.

    1979-01-01

    Several areas of applications of image processing to astronomy were identified and discussed. These areas include: (1) deconvolution for atmospheric seeing compensation; a comparison between maximum entropy and conventional Wiener algorithms; (2) polarization in galaxies from photographic plates; (3) time changes in M87 and methods of displaying these changes; (4) comparing emission line images in planetary nebulae; and (5) log intensity, hue saturation intensity, and principal component color enhancements of M82. Examples are presented of these techniques applied to a variety of objects.

  4. Recent Advances in Cardiovascular Magnetic Resonance: Techniques and Applications.

    PubMed

    Salerno, Michael; Sharif, Behzad; Arheden, Håkan; Kumar, Andreas; Axel, Leon; Li, Debiao; Neubauer, Stefan

    2017-06-01

    Cardiovascular magnetic resonance imaging has become the gold standard for evaluating myocardial function, volumes, and scarring. Additionally, cardiovascular magnetic resonance imaging is unique in its comprehensive tissue characterization, including assessment of myocardial edema, myocardial siderosis, myocardial perfusion, and diffuse myocardial fibrosis. Cardiovascular magnetic resonance imaging has become an indispensable tool in the evaluation of congenital heart disease, heart failure, cardiac masses, pericardial disease, and coronary artery disease. This review will highlight some recent novel cardiovascular magnetic resonance imaging techniques, concepts, and applications. © 2017 American Heart Association, Inc.

  5. Applicability of ultra-performance liquid chromatography-tandem mass spectrometry for heroin profiling.

    PubMed

    Lurie, Ira S; Toske, Steven G

    2008-04-25

    The applicability of ultra- performance liquid chromatography tandem-mass spectrometry (UPLC-MS/MS) for heroin profiling is described. The coupling of the high separation power of UPLC with the highly selective and sensitive detection of MS/MS is well suited for heroin profiling. An Acquity UPLC BEH C18 1.7 microm particle column (100 mm x 2.1mm) with binary gradients containing 1% formic acid (pH 2.0) or 10 mM ammonium bicarbonate (pH 10.0)/acetonitrile mixtures was investigated for the profiling. For MS/MS detection, an atmospheric pressure positive electrospray source was employed with multiple reaction monitoring (MRM). MRMs for individual basic impurities were generated for heroin profiling using low and high pH mobile phases, while MRMs for neutral impurities were generated using a high pH mobile phase. Compared to a pH 2.2 mobile phase, the use of a pH 10 mobile phase allowed for significantly greater sample loading, major selectivity differences, and lower MRM sensitivity. UPLC-MS/MS allowed for the highly selective and sensitive detection of many of the targeted solutes in seized heroin exhibits. Basic impurities detected included morphine, codeine, noscapine, papaverine and the previously unreported solutes reticuline, reticuline monoacetate (2 products), reticuline diacetate, narceine, codamine, laudanidine, cryptopine, laudanosine, and norlaudanosine. Neutral impurities found included N,3,6-triacetylnormorphine, N-acetylnorcodeine, N-acetylnornarcotine, 3,6-dimethoxy-4-acetyloxy-5-[2-(N-methylacetamido)]-ethylphenanthrene, and cis-n-acetylanhydronornarceine. The detection of these impurities, at levels as low as 10(-6)% w/w should allow for greatly enhanced heroin profiles.

  6. State-of-the-art in fast liquid chromatography-mass spectrometry for bio-analytical applications.

    PubMed

    Núñez, Oscar; Gallart-Ayala, Héctor; Martins, Claudia P B; Lucci, Paolo; Busquets, Rosa

    2013-05-15

    There is an increasing need of new bio-analytical methodologies with enough sensitivity, robustness and resolution to cope with the analysis of a large number of analytes in complex matrices in short analysis time. For this purpose, all steps included in any bio-analytical method (sampling, extraction, clean-up, chromatographic analysis and detection) must be taken into account to achieve good and reliable results with cost-effective methodologies. The purpose of this review is to describe the state-of-the-art of the most employed technologies in the period 2009-2012 to achieve fast analysis with liquid chromatography coupled to mass spectrometry (LC-MS) methodologies for bio-analytical applications. Current trends in fast liquid chromatography involve the use of several column technologies and this review will focus on the two most frequently applied: sub-2μm particle size packed columns to achieve ultra high pressure liquid chromatography (UHPLC) separations and porous-shell particle packed columns to attain high efficiency separations with reduced column back-pressures. Additionally, recent automated sample extraction and clean-up methodologies to reduce sample manipulation, variability and total analysis time in bio-analytical applications such as on-line solid phase extraction coupled to HPLC or UHPLC methods, or the use of other approaches such as molecularly imprinted polymers, restricted access materials, and turbulent flow chromatography will also be addressed. The use of mass spectrometry and high or even ultra-high resolution mass spectrometry to reduce sample manipulation and to solve ion suppression or ion enhancement and matrix effects will also be presented. The advantages and drawbacks of all these methodologies for fast and sensitive analysis of biological samples are going to be discussed by means of relevant applications.

  7. An Analysis of Performance Enhancement Techniques for Overset Grid Applications

    NASA Technical Reports Server (NTRS)

    Djomehri, J. J.; Biswas, R.; Potsdam, M.; Strawn, R. C.; Biegel, Bryan (Technical Monitor)

    2002-01-01

    The overset grid methodology has significantly reduced time-to-solution of high-fidelity computational fluid dynamics (CFD) simulations about complex aerospace configurations. The solution process resolves the geometrical complexity of the problem domain by using separately generated but overlapping structured discretization grids that periodically exchange information through interpolation. However, high performance computations of such large-scale realistic applications must be handled efficiently on state-of-the-art parallel supercomputers. This paper analyzes the effects of various performance enhancement techniques on the parallel efficiency of an overset grid Navier-Stokes CFD application running on an SGI Origin2000 machine. Specifically, the role of asynchronous communication, grid splitting, and grid grouping strategies are presented and discussed. Results indicate that performance depends critically on the level of latency hiding and the quality of load balancing across the processors.

  8. An Acoustic Communication Technique of Nanorobot Swarms for Nanomedicine Applications.

    PubMed

    Loscrí, Valeria; Vegni, Anna Maria

    2015-09-01

    In this contribution, we present a communication paradigm among nanodevices, based on acoustic vibrations for medical applications. We consider a swarm of nanorobots able to communicate in a distributed and decentralized fashion, propelled in a biological environment (i.e., the human brain). Each nanorobot is intended to i) recognize a cancer cell, ii) destroy it, and then iii) forward information about the presence of cancer formation to other nanorobots, through acoustic signals. The choice of acoustic waves as communication mean is related to the application context, where it is not advisable either to use indiscriminate chemical substances or electromagnetic waves. The effectiveness of the proposed approach is assessed in terms of achievement of the objective (i.e., to destroy the majority of tumor cells), and the velocity of detection and destruction of cancer cells, through a comparison with other related techniques.

  9. Surface Plasmon Resonance: A Versatile Technique for Biosensor Applications

    PubMed Central

    Nguyen, Hoang Hiep; Park, Jeho; Kang, Sebyung; Kim, Moonil

    2015-01-01

    Surface plasmon resonance (SPR) is a label-free detection method which has emerged during the last two decades as a suitable and reliable platform in clinical analysis for biomolecular interactions. The technique makes it possible to measure interactions in real-time with high sensitivity and without the need of labels. This review article discusses a wide range of applications in optical-based sensors using either surface plasmon resonance (SPR) or surface plasmon resonance imaging (SPRI). Here we summarize the principles, provide examples, and illustrate the utility of SPR and SPRI through example applications from the biomedical, proteomics, genomics and bioengineering fields. In addition, SPR signal amplification strategies and surface functionalization are covered in the review. PMID:25951336

  10. Application of adaptive antenna techniques to future commercial satellite communication

    NASA Technical Reports Server (NTRS)

    Ersoy, L.; Lee, E. A.; Matthews, E. W.

    1987-01-01

    The purpose of this contract was to identify the application of adaptive antenna technique in future operational commercial satellite communication systems and to quantify potential benefits. The contract consisted of two major subtasks. Task 1, Assessment of Future Commercial Satellite System Requirements, was generally referred to as the Adaptive section. Task 2 dealt with Pointing Error Compensation Study for a Multiple Scanning/Fixed Spot Beam Reflector Antenna System and was referred to as the reconfigurable system. Each of these tasks was further sub-divided into smaller subtasks. It should also be noted that the reconfigurable system is usually defined as an open-loop system while the adaptive system is a closed-loop system. The differences between the open- and closed-loop systems were defined. Both the adaptive and reconfigurable systems were explained and the potential applications of such systems were presented in the context of commercial communication satellite systems.

  11. Different classification techniques considering brain computer interface applications

    NASA Astrophysics Data System (ADS)

    Rezaei, Siamak; Tavakolian, Kouhyar; Moti Nasrabadi, Ali; Kamaledin Setarehdan, S.

    2006-06-01

    In this work the application of different machine learning techniques for classification of mental tasks from electroencephalograph (EEG) signals is investigated. The main application for this research is the improvement of brain computer interface (BCI) systems. For this purpose, Bayesian graphical network, neural network, Bayesian quadratic, Fisher linear and hidden Markov model classifiers are applied to two known EEG datasets in the BCI field. The Bayesian network classifier is used for the first time in this work for classification of EEG signals. The Bayesian network appeared to have a significant accuracy and more consistent classification compared to the other four methods. In addition to classical correct classification accuracy criteria, the mutual information is also used to compare the classification results with other BCI groups.

  12. Evaluating Credit Applications: A Validation of Multiattribute Utility Techniques Against a Real World Criterion,

    DTIC Science & Technology

    1980-06-01

    science research institute RESEARCH REPORT EVALUATING CREDIT APPLICATIONS: A Z’ VALIDATION OF MULTIATTRIBUTE UTILITY TECHNIQUES AGAINST A REAL WORLD...8217_, ", ’- .’.- .. .- ... . .. ,-*,. . .. EVALUATING CREDIT APPLICATIONS: A VALIDATION OF MULTIATTRIBUTE UTILITY TECHNIQUES AGAINST A REAL WORLD CRITERION...validation of multiattribute utility elicitation techniques. The techniques tested were the Holistic Orthogonal Parameter Estimation (HOPE) technique

  13. Review: Recent application of chiral liquid chromatography-tandem mass spectrometric methods for enantiomeric pharmaceutical and biomedical determinations.

    PubMed

    Nie, Yanfang; Liu, Xiumei; Yang, Xinmei; Zhao, Zhongxi

    2013-09-01

    The technology of analyzing the pharmacological and toxicological properties of chiral drugs has become more commonly utilized since the knowledge of the biological actions of enantiomers has been gradually acquired during the last few decades. This work reviews the applications of chiral liquid chromatography coupled to tandem mass spectrometry (LC-MS) for the analysis of chiral pharmaceuticals since 2005. The enantioselective determinations in pharmaceutical and biomedical fields with LC-MS are classified based on three mobile phase modes, including normal phase, reversed phase and polar organic solvent, in terms of their compatibility with various ionization sources and specific applications.

  14. Some essential techniques for developing efficient petascale applications

    NASA Astrophysics Data System (ADS)

    Kalé, L. V.

    2008-07-01

    Multiple petaflops-lass machines will appear during the coming year, and many multipetaflops machines are on the anvil. It will be a substantial challenge to make existing parallel CSE applications run efficiently on them, and even more challenging to design new applications that can effectively leverage the large computational power of these machines. Multicore chips and SMP nodes are becoming popular and pose challenges of their own. Further, a new set of challenges in productivity arise, especially if we wish to have a broader set of applications and people to use these machines. Reviewed here is a set of techniques that have proved useful in multiple parallel applications that have scaled to tens of thousands of processors, on machines such as the Blue Gene/L, Blue Gene/P, Cray XT3, and XT4. New challenges and potential solutions for the performance issues are identified. Issues presented by multicore chips and SMP nodes also rre addressed. Also reviewed are some new and old ideas for increasing productivity in parallel programming substantially.

  15. Application of hazard assessment techniques in the CISF design process

    SciTech Connect

    Thornton, J.R.; Henry, T.

    1997-10-29

    The Department of Energy has submitted to the NRC staff for review a topical safety analysis report (TSAR) for a Centralized Interim Storage Facility (CISF). The TSAR will be used in licensing the CISF when and if a site is designated. CISF1 design events are identified based on thorough review of design basis events (DBEs) previously identified by dry storage system suppliers and licensees and through the application of hazard assessment techniques. A Preliminary Hazards Assessment (PHA) is performed to identify design events applicable to a Phase 1 non site specific CISF. A PHA is deemed necessary since the Phase 1 CISF is distinguishable from previous dry store applications in several significant operational scope and design basis aspects. In addition to assuring all design events applicable to the Phase 1 CISF are identified, the PHA served as an integral part of the CISF design process by identifying potential important to safety and defense in depth facility design and administrative control features. This paper describes the Phase 1 CISF design event identification process and summarizes significant PHA contributions to the CISF design.

  16. Application of Acoustic Techniques for Characterization of Biological Samples

    NASA Astrophysics Data System (ADS)

    Tittmann, Bernhard R.; Ebert, Anne

    The atomic force microscope (AFM) is emerging as a powerful tool in cell biology. Originally developed for high-resolution imaging purposes, the AFM also has unique capabilities as a nano-indenter to probe the dynamic viscoelastic material properties of living cells in culture. In particular, AFM elastography combines imaging and indentation modalities to map the spatial distribution of cell mechanical properties, which in turn reflect the structure and function of the underlying cytoskeleton. Such measurements have contributed to our understanding of cell mechanics and cell biology and appear to be sensitive to the presence of disease in individual cells. Examples of applications and considerations on the effective capability of ultrasonic AFM techniques on biological samples (both mammalian and plant) are reported in this chapter. Included in the discussion is scanning near-field ultrasound holography an acoustic technique which has been used to image structure and in particular nanoparticles inside cells. For illustration an example that is discussed in some detail is a technique for rapid in vitro single-cell elastography. The technique is based on atomic force acoustic microscopy (AFAM) but (1) requires only a few minutes of scan time, (2) can be used on live cells briefly removed from most of the nutrient fluid, (3) does negligible harm or damage to the cell, (4) provides semi-quantitative information on the distribution of modulus across the cell, and (5) yields data with 1-10 nm resolution. The technique is shown to enable rapid assessment of physical/biochemical signals on the cell modulus and contributes to current understanding of cell mechanics.

  17. Current state-of-the-art of nontargeted metabolomics based on liquid chromatography-mass spectrometry with special emphasis in clinical applications.

    PubMed

    Yin, Peiyuan; Xu, Guowang

    2014-12-29

    Metabolomics, as a part of systems biology, has been widely applied in different fields of life science by studying the endogenous metabolites. The development and applications of liquid chromatography (LC) coupled with high resolution mass spectrometry (MS) greatly improve the achievable data quality in non-targeted metabolic profiling. However, there are still some emerging challenges to be covered in LC-MS based metabolomics. Here, recent approaches about sample collection and preparation, instrumental analysis, and data handling of LC-MS based metabolomics are summarized, especially in the analysis of clinical samples. Emphasis is put on the improvement of analytical techniques including the combination of different LC columns, isotope coded derivatization methods, pseudo-targeted LC-MS method, new data analysis algorithms and structural identification of important metabolites. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Plasma cleaning techniques and future applications in environmentally conscious manufacturing

    SciTech Connect

    Ward, P.P.

    1995-07-01

    Plasmas have frequently been used in industry as a last step surface preparation technique in an otherwise predominantly wet-etch process. The limiting factor in the usefulness of plasma cleaning techniques has been the rate at which organic materials are removed. Recent research in the field of plasma chemistry has provided some understanding of plasma processes. By controlling plasma conditions and gas mixtures, ultra-fast plasma cleaning and etching is possible. With enhanced organic removal rates, plasma processes become more desirable as an environmentally sound alternative to traditional solvent or acid dominated process, not only as a cleaning tool, but also as a patterning and machining tool. In this paper, innovations in plasma processes are discussed including enhanced plasma etch rates via plasma environment control and aggressive gas mixtures. Applications that have not been possible with the limited usefulness of past plasma processes are now approaching the realm of possibility. Some of these possible applications will be discussed along with their impact to environmentally conscious manufacturing.

  19. Tutorial on techniques and applications for natural language processing

    SciTech Connect

    Hayes, P.J.; Carbonell, J.G.

    1983-10-17

    Natural language communication with computers has long been a major goal of Artificial Intelligence both for what it can tell us about intelligence in general and for its practical utility - data bases, software packages, and Al-based expert systems all require flexible interfaces to a growing community of users who are not able or do not wish to communicate with computers in formal, artificial command languages. Whereas many of the fundamental problems of general natural language processing (NLP) by machine remain to be solved, the area has matured in recent years to the point where practical natural language interfaces to software systems can be constructed in many restricted, but nevertheless useful, circumstances. This tutorial is intended to survey the current state of applied natural language processing by presenting computationally effective NLP techniques, by discussing the range of capabilities these techniques provide for NLP systems, an by discussing their current limitations. Following the introduction, this document is divided into two major sections: the first on language recognition strategies at the single sentence level, and the second on language processing issues that arise during interactive dialogues. In both cases, we concentrate on those aspects of the problem appropriate for interactive natural language interfaces, but relate the techniques and systems discussed to more general work on natural language, independent of application domain.

  20. Surface dating of bricks, an application of luminescence techniques

    NASA Astrophysics Data System (ADS)

    Galli, Anna; Martini, Marco; Maspero, Francesco; Panzeri, Laura; Sibilia, Emanuela

    2014-05-01

    Luminescence techniques are a powerful tool to date archaeological ceramic materials and geological sediments. Thermoluminescence (TL) is widely used for bricks dating to reconstruct the chronology of urban complexes and the development of human cultures. However, it can sometimes be inconclusive, since TL assesses the firing period of bricks, which can be reused, even several centuries later. This problem can be circumvented using a dating technique based on a resetting event different from the last heating. OSL (Optically Stimulated Luminescence) exploits the last light exposition of the brick surface, which resets the light-sensitive electron traps until the surface is definitely shielded by mortar and superimposed bricks. This advanced application (surface dating) has been successfully attempted on rocks, marble and stone artifacts, but not yet on bricks. A recent conservation campaign at the Certosa di Pavia gave the opportunity to sample some bricks belonging to a XVII century collapsed wall, still tied to their mortars. This was an advantageous condition to test this technique, comparing the dating results with precise historical data. This attempt gave satisfactory results, allowing to identify bricks surely reused and to fully confirm that the edification of the perimetral wall occurred at the end of XVII century.

  1. A Review of Diagnostic Techniques for ISHM Applications

    NASA Technical Reports Server (NTRS)

    Patterson-Hine, Ann; Biswas, Gautam; Aaseng, Gordon; Narasimhan, Sriam; Pattipati, Krishna

    2005-01-01

    System diagnosis is an integral part of any Integrated System Health Management application. Diagnostic applications make use of system information from the design phase, such as safety and mission assurance analysis, failure modes and effects analysis, hazards analysis, functional models, fault propagation models, and testability analysis. In modern process control and equipment monitoring systems, topological and analytic , models of the nominal system, derived from design documents, are also employed for fault isolation and identification. Depending on the complexity of the monitored signals from the physical system, diagnostic applications may involve straightforward trending and feature extraction techniques to retrieve the parameters of importance from the sensor streams. They also may involve very complex analysis routines, such as signal processing, learning or classification methods to derive the parameters of importance to diagnosis. The process that is used to diagnose anomalous conditions from monitored system signals varies widely across the different approaches to system diagnosis. Rule-based expert systems, case-based reasoning systems, model-based reasoning systems, learning systems, and probabilistic reasoning systems are examples of the many diverse approaches ta diagnostic reasoning. Many engineering disciplines have specific approaches to modeling, monitoring and diagnosing anomalous conditions. Therefore, there is no "one-size-fits-all" approach to building diagnostic and health monitoring capabilities for a system. For instance, the conventional approaches to diagnosing failures in rotorcraft applications are very different from those used in communications systems. Further, online and offline automated diagnostic applications are integrated into an operations framework with flight crews, flight controllers and maintenance teams. While the emphasis of this paper is automation of health management functions, striking the correct balance between

  2. Application of optical spectroscopic techniques for disease diagnosis

    NASA Astrophysics Data System (ADS)

    Saha, Anushree

    Optical spectroscopy, a truly non-invasive tool for remote diagnostics, is capable of providing valuable information on the structure and function of molecules. However, most spectroscopic techniques suffer from drawbacks, which limit their application. As a part of my dissertation work, I have developed theoretical and experimental methods to address the above mentioned issues. I have successfully applied these methods for monitoring the physical, chemical and biochemical parameters of biomolecules involved in some specific life threatening diseases like lead poisoning and age-related macular degeneration (AMD). I presented optical studies of melanosomes, which are one of the vital organelles in the human eye, also known to be responsible for a disease called age-related macular degeneration (AMD), a condition of advanced degeneration which causes progressive blindness. I used Raman spectroscopy, to first chemically identify the composition of melanosome, and then monitor the changes in its functional and chemical behavior due to long term exposure to visible light. The above study, apart from explaining the role of melanosomes in AMD, also sets the threshold power for lasers used in surgeries and other clinical applications. In the second part of my dissertation, a battery of spectroscopic techniques was successfully applied to explore the different binding sites of lead ions with the most abundant carrier protein molecule in our circulatory system, human serum albumin. I applied optical spectroscopic tools for ultrasensitive detection of heavy metal ions in solution which can also be used for lead detection at a very early stage of lead poisoning. Apart from this, I used Raman microspectroscopy to study the chemical alteration occurring inside a prostate cancer cell as a result of a treatment with a low concentrated aqueous extract of a prospective drug, Nerium Oleander. The experimental methods used in this study has tremendous potential for clinical

  3. Application of an online ion-chromatography-based instrument for gradient flux measurements of speciated nitrogen and sulfur

    NASA Astrophysics Data System (ADS)

    Rumsey, Ian C.; Walker, John T.

    2016-06-01

    The dry component of total nitrogen and sulfur atmospheric deposition remains uncertain. The lack of measurements of sufficient chemical speciation and temporal extent make it difficult to develop accurate mass budgets and sufficient process level detail is not available to improve current air-surface exchange models. Over the past decade, significant advances have been made in the development of continuous air sampling measurement techniques, resulting with instruments of sufficient sensitivity and temporal resolution to directly quantify air-surface exchange of nitrogen and sulfur compounds. However, their applicability is generally restricted to only one or a few of the compounds within the deposition budget. Here, the performance of the Monitor for AeRosols and GAses in ambient air (MARGA 2S), a commercially available online ion-chromatography-based analyzer is characterized for the first time as applied for air-surface exchange measurements of HNO3, NH3, NH4+, NO3-, SO2 and SO42-. Analytical accuracy and precision are assessed under field conditions. Chemical concentrations gradient precision are determined at the same sampling site. Flux uncertainty measured by the aerodynamic gradient method is determined for a representative 3-week period in fall 2012 over a grass field. Analytical precision and chemical concentration gradient precision were found to compare favorably in comparison to previous studies. During the 3-week period, percentages of hourly chemical concentration gradients greater than the corresponding chemical concentration gradient detection limit were 86, 42, 82, 73, 74 and 69 % for NH3, NH4+, HNO3, NO3-, SO2 and SO42-, respectively. As expected, percentages were lowest for aerosol species, owing to their relatively low deposition velocities and correspondingly smaller gradients relative to gas phase species. Relative hourly median flux uncertainties were 31, 121, 42, 43, 67 and 56 % for NH3, NH4+, HNO3, NO3-, SO2 and SO42-, respectively. Flux

  4. AI techniques for a space application scheduling problem

    NASA Technical Reports Server (NTRS)

    Thalman, N.; Sparn, T.; Jaffres, L.; Gablehouse, D.; Judd, D.; Russell, C.

    1991-01-01

    Scheduling is a very complex optimization problem which can be categorized as an NP-complete problem. NP-complete problems are quite diverse, as are the algorithms used in searching for an optimal solution. In most cases, the best solutions that can be derived for these combinatorial explosive problems are near-optimal solutions. Due to the complexity of the scheduling problem, artificial intelligence (AI) can aid in solving these types of problems. Some of the factors are examined which make space application scheduling problems difficult and presents a fairly new AI-based technique called tabu search as applied to a real scheduling application. the specific problem is concerned with scheduling application. The specific problem is concerned with scheduling solar and stellar observations for the SOLar-STellar Irradiance Comparison Experiment (SOLSTICE) instrument in a constrained environment which produces minimum impact on the other instruments and maximizes target observation times. The SOLSTICE instrument will gly on-board the Upper Atmosphere Research Satellite (UARS) in 1991, and a similar instrument will fly on the earth observing system (Eos).

  5. Modular Ontology Techniques and their Applications in the Biomedical Domain.

    PubMed

    Pathak, Jyotishman; Johnson, Thomas M; Chute, Christopher G

    2008-08-05

    In the past several years, various ontologies and terminologies such as the Gene Ontology have been developed to enable interoperability across multiple diverse medical information systems. They provide a standard way of representing terms and concepts thereby supporting easy transmission and interpretation of data for various applications. However, with their growing utilization, not only has the number of available ontologies increased considerably, but they are also becoming larger and more complex to manage. Toward this end, a growing body of work is emerging in the area of modular ontologies where the emphasis is on either extracting and managing "modules" of an ontology relevant to a particular application scenario (ontology decomposition) or developing them independently and integrating into a larger ontology (ontology composition). In this paper, we investigate state-of-the-art approaches in modular ontologies focusing on techniques that are based on rigorous logical formalisms as well as well-studied graph theories. We analyze and compare how such approaches can be leveraged in developing tools and applications in the biomedical domain. We conclude by highlighting some of the limitations of the modular ontology formalisms and put forward additional requirements to steer their future development.

  6. Modern Thin-Layer Chromatography.

    ERIC Educational Resources Information Center

    Poole, Colin F.; Poole, Salwa K.

    1989-01-01

    Some of the important modern developments of thin-layer chromatography are introduced. Discussed are the theory and instrumentation of thin-layer chromatography including multidimensional and multimodal techniques. Lists 53 references. (CW)

  7. 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.

  8. pH-zone-refining counter-current chromatography: origin, mechanism, procedure and applications.

    PubMed

    Ito, Yoichiro

    2013-01-04

    Since 1980, high-speed counter-current chromatography (HSCCC) has been used for separation and purification of natural and synthetic products in a standard elution mode. In 1991, a novel elution mode called pH-zone refining CCC was introduced from an incidental discovery that an organic acid in the sample solution formed the sharp peak of an acid analyte. The cause of this sharp peak formation was found to be bromoacetic acid present in the sample solution which formed a sharp trailing border to trap the acidic analyte. Further studies on the separation of DNP-amino acids with three spacer acids in the stationary phase revealed that increased sample size resulted in the formation of fused rectangular peaks, each preserving high purity and zone pH with sharp boundaries. The mechanism of this phenomenon was found to be the formation of a sharp trailing border of an acid (retainer) in the column which moves at a lower rate than that of the mobile phase. In order to facilitate the application of the method, a new method was devised using a set of retainer and eluter to form a sharp retainer rear border which moves through the column at a desired rate regardless of the composition of the two-phase solvent system. This was achieved by adding the retainer in the stationary phase and the eluter in the mobile phase at a given molar ratio. Using this new method the hydrodynamics of pH-zone-refining CCC was diagrammatically illustrated by three acidic samples. In this review paper, typical pH-zone-refining CCC separations were presented, including affinity separations with a ligand and a separation of a racemic mixture using a chiral selector in the stationary phase. Major characteristics of pH-zone-refining CCC over conventional HSCCC are as follows: the sample loading capacity is increased over 10 times; fractions are highly concentrated near saturation level; yield is improved by increasing the sample size; minute charged compounds are concentrated and detected at the peak

  9. 1,1-dimethylhydrazine as a high purity nitrogen source for MOVPE-water reduction and quantification using nuclear magnetic resonance, gas chromatography-atomic emission detection spectroscopy and cryogenic-mass spectroscopy analytical techniques

    SciTech Connect

    Odedra, R.; Smith, L.M.; Rushworth, S.A.

    2000-01-01

    Hydrazine derivatives are attractive low temperature nitrogen sources for use in MOVPE due to their low thermal stability. However their purification and subsequent analysis has not previously been investigated in depth for this application. A detailed study on 1,1-dimethylhydrazine {l{underscore}brace}(CH{sub 3}){sub 2}N-NH{sub 2}{r{underscore}brace} purified by eight different methods and the subsequent quantitative measurements of water present in the samples obtained is reported here. A correlation between {sup 1}H nuclear magnetic resonance spectroscopy (NMR), gas chromatography-atomic emission detection (GC-AED) and cryogenic mass spectroscopy (Cryogenic-MS) has been performed. All three analysis techniques can be used to measure water in the samples and with the best purification the water content can be lowered well below 100 ppm. The high purity of this material has been demonstrated by growth results and the state-of-the-art performance of laser diodes.

  10. Laser heterodyne detection techniques. [for atmospheric monitoring applications

    NASA Technical Reports Server (NTRS)

    Menzies, R. T.

    1976-01-01

    The principles of heterodyne radiometry are examined, taking into account thermal radiation, the Dicke microwave radiometer, photomixing in the infrared, and signal-to-noise considerations. The passive heterodyne radiometer is considered and a description is presented of heterodyne techniques in active monitoring systems. Attention is given to gas emissivities in the infrared, component requirements, experimental heterodyne detection of gases, a comparison of the passive heterodyne radiometer with the Michelson interferometer-spectrometer, airborne monitoring applications, turbulence effects on passive heterodyne radiometry, sensitivity improvements with heterodyning, atmosphere-induced degradation of bistatic system performance, pollutant detection experiments with a bistatic system, and the airborne laser absorption spectrometer. Future improvements in spectral flexibility are also discussed.

  11. An ultra-low-power filtering technique for biomedical applications.

    PubMed

    Zhang, Tan-Tan; Mak, Pui-In; Vai, Mang-I; Mak, Peng-Un; Wan, Feng; Martins, R P

    2011-01-01

    This paper describes an ultra-low-power filtering technique for biomedical applications designated as T-wave sensing in heart-activities detection systems. The topology is based on a source-follower-based Biquad operating in the sub-threshold region. With the intrinsic advantages of simplicity and high linearity of the source-follower, ultra-low-cutoff filtering can be achieved, simultaneously with ultra low power and good linearity. An 8(th)-order 2.4-Hz lowpass filter design example optimized in a 0.35-μm CMOS process was designed achieving over 85-dB dynamic range, 74-dB stopband attenuation and consuming only 0.36 nW at a 3-V supply.

  12. Spaceborne synthetic-aperture imaging radars - Applications, techniques, and technology

    NASA Technical Reports Server (NTRS)

    Elachi, C.; Bicknell, T.; Jordan, R. L.; Wu, C.

    1982-01-01

    In June 1978, the Seasat satellite was placed into orbit around the earth with a synthetic-aperture imaging radar (SAR) as one of the payload sensors. The Seasat SAR provided, for the first time, synoptic radar images of the earth's surface with a resolution of 25 m. In November 1981, the second imaging radar was successfully operated from space on the Shuttle. The Shuttle Imaging Radar-A acquired images over a variety of regions around the world with an imaging geometry different from the one used by the Seasat SAR. The spaceborne SAR principle is discussed, taking into account ambiguities, orbital and environmental factors, range curvature and range walk, surface interaction mechanisms, thermal and speckle noise, key tradeoff parameters, and nonconventional SAR systems. Attention is also given to spaceborne SAR sensors, the digital processing of spaceborne SAR data, the optical processing of spaceborne SAR data, postimage formation processing, data interpretation techniques and applications, and the next decade.

  13. Application of object oriented programming techniques in front end computers

    SciTech Connect

    Skelly, J.F.

    1997-11-01

    The Standard Model for accelerator control systems describes two levels of computers, often called Console Level Computers (CLCs) and Front End Computers (FECs), joined by a network. The Front End Computer (FEC) environment imposes special demands on software, beyond real time performance and robustness. FEC software must manage a diverse inventory of devices with individualistic timing requirements and hardware interfaces. It must implement network services which export device access to the control system at large, interpreting a uniform network communications protocol into the specific control requirements of the individual devices. Object oriented languages provide programming techniques which neatly address these challenges, and also offer benefits in terms of maintainability and flexibility. Applications are discussed which exhibit the use of inheritance, multiple inheritance and inheritance trees, and polymorphism to address the needs of FEC software.

  14. Application of Ion Chromatography to the Investigation of Real-World Samples

    ERIC Educational Resources Information Center

    Whelan, Rebecca J.; Hannon, Theresa E.; Zare, Richard N.

    2004-01-01

    The use of ion chromatography (IC) as a means to teach important analytical concepts while giving the students a valuable opportunity to identify and investigate a real-world system of interest to them is described. A single IC apparatus can be tailored for different classes of analyses by the selection of different column-eluent combinations.

  15. Mass spectrometry detection in comprehensive liquid chromatography: basic concepts, instrumental aspects, applications and trends.

    PubMed

    Donato, Paola; Cacciola, Francesco; Tranchida, Peter Quinto; Dugo, Paola; Mondello, Luigi

    2012-01-01

    The review, as can be deduced from the title, focuses on both theoretical and practical aspects of the use of mass spectrometry as a third, added dimension to a comprehensive LC (LC × LC) system, generating the most powerful analytical tool today for non-volatile analytes. The first part deals with the technical requirements for linkage of an LC × LC system to an MS one, including the choice of the mobile phase (buffer and salts), flow rate (splitting), type of ionization (interface); advantages and disadvantages of off-line and on-line methods are discussed, as well. A discussion of the various aspects of instrumentation is provided, both from a chromatographic and mass spectrometry standpoint, with particular emphasis directed to the choice of column sets, spatial resolution, mass resolving power, mass accuracy, and tandem-MS capabilities. The extent to which mass spectrometry may be of aid in unraveling column-outlet multicompound bands is highlighted, along with its effectiveness as a chromatographic detector of excellent sensitivity, universality yet with potential in terms of selectivity and amenability to quantitative analysis over a wide dynamic range. The following section of the review contains significant applications of comprehensive two-dimensional LC coupled to MS in different areas of research, with details on interfaces, column stationary phases, modulation and MS parameters. It is not the intention of the authors to provide a comprehensive description of the techniques, but merely to discuss only those aspects which are essential for successful applications of the LC-MS combination. The reader will be acquainted with the enormous potential of this hyphenated technique, and the factors and instrumental developments that have concurred to make it emerge to a central role in specialized fields, such as proteomics.

  16. Optically heated ultra-fast-cycling gas chromatography module for separation of direct sampling and online monitoring applications.

    PubMed

    Fischer, Michael; Wohlfahrt, Sebastian; Varga, Janos; Matuschek, Georg; Saraji-Bozorgzad, Mohammad R; Denner, Thomas; Walte, Andreas; Zimmermann, Ralf

    2015-09-01

    This work describes an ultrafast-cycling gas chromatography module (fast-GC module) for direct-sampling gas chromatography/mass spectrometry (GC-MS). The sample can be introduced into the fast-GC module using a common GC injector or any GC × GC modulator. The new fast-GC module offers the possibility to conduct a complete temperature cycle within 30 s. Its thermal mass is minimized by using a specially developed home-built fused silica capillary column stack and a halogen lamp for heat generation, both placed inside a gold-coated quartz glass cylinder. A high airflow blower enables rapid cooling. The new device is highly flexible concerning the used separation column, the applied temperature program, and the integration into existing systems. An application of the fast-GC module is shown in this work by thermal analysis coupled to gas chromatography-mass spectrometry (TA-GC-MS). The continuously evolving gases of the TA are modulated by a liquid CO2 modulator. Because of the rapid cycling of the fast-GC module, it is possible to obtain the best separation while maintaining the online character of the TA. Restrictions in separation and retention time shifting, known from isothermal and normal ramped fast-GC systems, are overcome.

  17. Multi-mode application of graphene quantum dots bonded silica stationary phase for high performance liquid chromatography.

    PubMed

    Wu, Qi; Sun, Yaming; Zhang, Xiaoli; Zhang, Xia; Dong, Shuqing; Qiu, Hongdeng; Wang, Litao; Zhao, Liang

    2017-04-07

    Graphene quantum dots (GQDs), which possess hydrophobic, hydrophilic, π-π stacking and hydrogen bonding properties, have great prospect in HPLC. In this study, a novel GQDs bonded silica stationary phase was prepared and applied in multiple separation modes including normal phase, reversed phase and hydrophilic chromatography mode. Alkaloids, nucleosides and nucleobases were chosen as test compounds to evaluate the separation performance of this column in hydrophilic chromatographic mode. The tested polar compounds achieved baseline separation and the resolutions reached 2.32, 4.62, 7.79, 1.68 for thymidine, uridine, adenosine, cytidine and guanosine. This new column showed satisfactory chromatographic performance for anilines, phenols and polycyclic aromatic hydrocarbons in normal and reversed phase mode. Five anilines were completely separated within 10min under the condition of mobile phase containing only 10% methanol. The effect of water content, buffer concentration and pH on chromatographic separation was further investigated, founding that this new stationary phase showed a complex retention mechanism of partitioning, adsorption and electrostatic interaction in hydrophilic chromatography mode, and the multiple retention interactions such as π-π stacking and π-π electron-donor-acceptor interaction played an important role during the separation process. This GQDs bonded column, which allows us to adjust appropriate chromatography mode according to the properties of analytes, has possibility in actual application after further research.

  18. Nonlinear plasmonic imaging techniques and their biological applications

    NASA Astrophysics Data System (ADS)

    Deka, Gitanjal; Sun, Chi-Kuang; Fujita, Katsumasa; Chu, Shi-Wei

    2017-01-01

    Nonlinear optics, when combined with microscopy, is known to provide advantages including novel contrast, deep tissue observation, and minimal invasiveness. In addition, special nonlinearities, such as switch on/off and saturation, can enhance the spatial resolution below the diffraction limit, revolutionizing the field of optical microscopy. These nonlinear imaging techniques are extremely useful for biological studies on various scales from molecules to cells to tissues. Nevertheless, in most cases, nonlinear optical interaction requires strong illumination, typically at least gigawatts per square centimeter intensity. Such strong illumination can cause significant phototoxicity or even photodamage to fragile biological samples. Therefore, it is highly desirable to find mechanisms that allow the reduction of illumination intensity. Surface plasmon, which is the collective oscillation of electrons in metal under light excitation, is capable of significantly enhancing the local field around the metal nanostructures and thus boosting up the efficiency of nonlinear optical interactions of the surrounding materials or of the metal itself. In this mini-review, we discuss the recent progress of plasmonics in nonlinear optical microscopy with a special focus on biological applications. The advancement of nonlinear imaging modalities (including incoherent/coherent Raman scattering, two/three-photon luminescence, and second/third harmonic generations that have been amalgamated with plasmonics), as well as the novel subdiffraction limit imaging techniques based on nonlinear behaviors of plasmonic scattering, is addressed.

  19. Averaging sensors technique for active vibration control applications

    NASA Astrophysics Data System (ADS)

    Cinquemani, S.; Cazzulani, G.; Braghin, F.; Resta, F.

    2013-04-01

    Fiber Bragg Gratings (FBG) sensors have a great potential in active vibration control of smart structures thanks to their small transversal size and the possibility to make an array of many sensors. The paper deals with the opportunity to reduce vibration in structures by using distributed sensors embedded in carbon fiber structures through the so called sensors-averaging technique. This method provides a properly weighted average of the outputs of a distributed array of sensors generating spatial filters on a broad range of undesired resonance modes without adversely affecting phase and amplitude. This approach combines the positive sides of decentralized control techniques as the control forces applied to the system are independent of one another, while, as for the centralized controls it has the possibility to exploit the information from all the sensors. The ability to easily manage this information allows to synthesize an efficient modal controller. Furthermore it enables to evaluate the stability of the control, the effects of spillover and the consequent effectiveness in reducing vibration. Theoretical aspects are supported by experimental applications on a large flexible system composed of a thin cantilever beam with 30 longitudinal FBG sensors and 6 piezoelectric actuators (PZT).

  20. Application of computerized tomography techniques to tokamak diagnostics

    NASA Astrophysics Data System (ADS)

    Stalker, K. T.; Kelly, J. G.

    1980-08-01

    A Coded Aperture Imaging System (CAIS) has been developed at Sandia National Laboratories to image the motion of nuclear fuel rods undergoing tests simulating accident conditions within a liquid metal fast breeder reactor. The tests require that the motion of the test fuel be monitored while it is immersed in a liquid sodium coolant precluding the use of normal optical means of imaging. However, using the fission gamma rays emitted by the fuel itself and coded aperture techniques, images with 1.5 mm radial and 5 mm axial resolution have been attained. Using an electro-optical detection system coupled to a high speed motion picture camera a time resolution of one millisecond can be achieved. This paper will discuss the application of coded aperture imaging to the problem, including the design of the one-dimensional Fresnel zone plate apertures used and the special problems arising from the reactor environment and use of high energy gamma ray photons to form the coded image. Also to be discussed will be the reconstruction techniques employed and the effect of various noise sources on system performance. Finally, some experimental results obtained using the system will be presented.

  1. Nonlinear plasmonic imaging techniques and their biological applications

    NASA Astrophysics Data System (ADS)

    Deka, Gitanjal; Sun, Chi-Kuang; Fujita, Katsumasa; Chu, Shi-Wei

    2016-07-01

    Nonlinear optics, when combined with microscopy, is known to provide advantages including novel contrast, deep tissue observation, and minimal invasiveness. In addition, special nonlinearities, such as switch on/off and saturation, can enhance the spatial resolution below the diffraction limit, revolutionizing the field of optical microscopy. These nonlinear imaging techniques are extremely useful for biological studies on various scales from molecules to cells to tissues. Nevertheless, in most cases, nonlinear optical interaction requires strong illumination, typically at least gigawatts per square centimeter intensity. Such strong illumination can cause significant phototoxicity or even photodamage to fragile biological samples. Therefore, it is highly desirable to find mechanisms that allow the reduction of illumination intensity. Surface plasmon, which is the collective oscillation of electrons in metal under light excitation, is capable of significantly enhancing the local field around the metal nanostructures and thus boosting up the efficiency of nonlinear optical interactions of the surrounding materials or of the metal itself. In this mini-review, we discuss the recent progress of plasmonics in nonlinear optical microscopy with a special focus on biological applications. The advancement of nonlinear imaging modalities (including incoherent/coherent Raman scattering, two/three-photon luminescence, and second/third harmonic generations that have been amalgamated with plasmonics), as well as the novel subdiffraction limit imaging techniques based on nonlinear behaviors of plasmonic scattering, is addressed.

  2. Prewarping techniques in imaging: applications in nanotechnology and biotechnology

    NASA Astrophysics Data System (ADS)

    Poonawala, Amyn; Milanfar, Peyman

    2005-03-01

    In all imaging systems, the underlying process introduces undesirable distortions that cause the output signal to be a warped version of the input. When the input to such systems can be controlled, pre-warping techniques can be employed which consist of systematically modifying the input such that it cancels out (or compensates for) the process losses. In this paper, we focus on the mask (reticle) design problem for 'optical micro-lithography', a process similar to photographic printing used for transferring binary circuit patterns onto silicon wafers. We use a pixel-based mask representation and model the above process as a cascade of convolution (aerial image formation) and thresholding (high-contrast recording) operations. The pre-distorted mask is obtained by minimizing the norm of the difference between the 'desired' output image and the 'reproduced' output image. We employ the regularization framework to ensure that the resulting masks are close-to-binary as well as simple and easy to fabricate. Finally, we provide insight into two additional applications of pre-warping techniques. First is 'e-beam lithography', used for fabricating nano-scale structures, and second is 'electronic visual prosthesis' which aims at providing limited vision to the blind by using a prosthetic retinally implanted chip capable of electrically stimulating the retinal neuron cells.

  3. Investigating Coincidence Techniques in Biomedical Applications of Neutron Activation Analysis

    NASA Astrophysics Data System (ADS)

    Chowdhury, P.; Gramer, R.; Tandel, S. K.; Reinhardt, C. J.

    2004-05-01

    While neutron activation analysis has been widely used in biomedical applications for some time, the use of non-radioactive tracer techniques, to monitor, for example, organ blood flow, is more recent. In these studies, pre-clinical animal models are injected with micro-spheres labeled with stable isotopes of elements that have a high neutron absorption cross-section. Subsequently, samples of blood and/or tissue from different locations in the body are subjected to neutron activation analysis to measure the propagation of the labeled micro-spheres through the body. Following irradiation, the counting (with high-resolution Ge detectors) is typically delayed by a few days to dissipate short-lived activity in the samples and improve signal-to-noise for the peaks of interest in the activation spectrum. The aim of the present study was to investigate whether coincidence techniques (for isotopes which decay via two-photon cascades) could improve signal-to-noise and turn-around times. The samples were irradiated at the 1 MW research reactor at the UMass Lowell Radiation Laboratory. The analysis of the multi-parameter coincidence data recorded in event-mode will be presented and compared with the standard method of recording singles spectra.

  4. Surgical Tips in Frozen Abdomen Management: Application of Coliseum Technique.

    PubMed

    Kyriazanos, Ioannis D; Manatakis, Dimitrios K; Stamos, Nikolaos; Stoidis, Christos

    2015-01-01

    Wound dehiscence is a serious postoperative complication, with an incidence of 0.5-3% after primary closure of a laparotomy incision, and represents an acute mechanical failure of wound healing. Relatively recently the concept of "intentional open abdomen" was described and both clinical entities share common pathophysiological and clinical pathways ("postoperative open abdominal wall"). Although early reconstruction is the target, a significant proportion of patients will develop adhesions between abdominal viscera and the anterolateral abdominal wall, a condition widely recognized as "frozen abdomen," where delayed wound closure appears as the only realistic alternative. We report our experience with a patient who presented with frozen abdomen after wound dehiscence due to surgical site infection and application of the "Coliseum technique" for its definitive surgical management. This novel technique represents an innovative alternative to abdominal exploration, for cases of "malignant" frozen abdomen due to peritoneal carcinomatosis. Lifting the edges of the surgical wound upwards and suspending them under traction by threads from a retractor positioned above the abdomen facilitates approach to the peritoneal cavity, optimizes exposure of intra-abdominal organs, and prevents operative injury to the innervation and blood supply of abdominal wall musculature, a crucial step for subsequent hernia repair.

  5. Imaging In focus: Reflected light imaging: Techniques and applications.

    PubMed

    Guggenheim, Emily J; Lynch, Iseult; Rappoport, Joshua Z

    2017-02-01

    Reflectance imaging is a broad term that describes the formation of images by the detection of illumination light that is back-scattered from reflective features within a sample. Reflectance imaging can be performed in a variety of different configurations, such as confocal, oblique angle illumination, structured illumination, interferometry and total internal reflectance, permitting a plethora of biomedical applications. Reflectance imaging has proven indispensable for critical investigations into the safety and understanding of biomedically and environmentally relevant nano-materials, an area of high priority and investment. The non-destructive in vivo imaging ability of reflectance techniques permits alternative diagnostic strategies that may eventually facilitate the eradication of some invasive biopsy procedures. Reflectance can also provide additional structural information and clarity necessary in fluorescent based in vivo studies. Near-coverslip interrogation techniques, such as reflectance interferometry and total internal reflection, have provided a label free means to investigate cell-surface contacts, cell motility and vesicle trafficking in vivo and in vitro. Other key advances include the ability to acquire superresolution reflectance images providing increased spatial resolution.

  6. Application of simulation techniques for internal corrosion prediction

    SciTech Connect

    Palacios T, C.A.; Hernandez, Y.

    1997-08-01

    Characterization of corrosion in the oil and gas industry is becoming of increasing importance for safety reasons as well as for the preservation of production facilities; to prevent down time and damage to the environment. This article presents the methodology used by this company to characterize the corrosion behavior of the whole production facility, taking into consideration the hydrodynamic and thermodynamic conditions of the produced fluids (flow velocities, flow pattern, liquid holdup, pressure, temperature, etc.) as they flow from the reservoir through the surface installations (flowlines, gas/oil gathering and transmission lines, gas processing plants, artificial lift systems, etc.). The methodology uses Petroleum Engineering and Two-Phase modeling techniques to: (1) optimize the entire production system to obtain the most efficient objective flow rate taking into consideration the corrosive/erosive nature of the produced fluid and (2) characterize the corrosive nature of the produced fluid as it flows through the above mentioned installations. The modeling techniques were performed using commercially available simulators and CO{sub 2} corrosion rates were determined using well known published correlations. For H{sub 2}S corrosion, NACE MR0175 criteria is applied. The application of this methodology has allowed corrosion control strategies, protection and monitoring criteria, inhibitor optimization and increased the effectiveness of already existing corrosion control systems.

  7. The applications of statistical quantification techniques in nanomechanics and nanoelectronics.

    PubMed

    Mai, Wenjie; Deng, Xinwei

    2010-10-08

    Although nanoscience and nanotechnology have been developing for approximately two decades and have achieved numerous breakthroughs, the experimental results from nanomaterials with a higher noise level and poorer repeatability than those from bulk materials still remain as a practical issue, and challenge many techniques of quantification of nanomaterials. This work proposes a physical-statistical modeling approach and a global fitting statistical method to use all the available discrete data or quasi-continuous curves to quantify a few targeted physical parameters, which can provide more accurate, efficient and reliable parameter estimates, and give reasonable physical explanations. In the resonance method for measuring the elastic modulus of ZnO nanowires (Zhou et al 2006 Solid State Commun. 139 222-6), our statistical technique gives E = 128.33 GPa instead of the original E = 108 GPa, and unveils a negative bias adjustment f(0). The causes are suggested by the systematic bias in measuring the length of the nanowires. In the electronic measurement of the resistivity of a Mo nanowire (Zach et al 2000 Science 290 2120-3), the proposed new method automatically identified the importance of accounting for the Ohmic contact resistance in the model of the Ohmic behavior in nanoelectronics experiments. The 95% confidence interval of resistivity in the proposed one-step procedure is determined to be 3.57 +/- 0.0274 x 10( - 5) ohm cm, which should be a more reliable and precise estimate. The statistical quantification technique should find wide applications in obtaining better estimations from various systematic errors and biased effects that become more significant at the nanoscale.

  8. An Ultra-Trace Analysis Technique for SF6 Using Gas Chromatography with Negative Ion Chemical Ionization Mass Spectrometry.

    PubMed

    Jong, Edmund C; Macek, Paul V; Perera, Inoka E; Luxbacher, Kray D; McNair, Harold M

    2015-07-01

    Sulfur hexafluoride (SF6) is widely used as a tracer gas because of its detectability at low concentrations. This attribute of SF6 allows the quantification of both small-scale flows, such as leakage, and large-scale flows, such as atmospheric currents. SF6's high detection sensitivity also facilitates greater usage efficiency and lower operating cost for tracer deployments by reducing quantity requirements. The detectability of SF6 is produced by its high molecular electronegativity. This property provides a high potential for negative ion formation through electron capture thus naturally translating to selective detection using negative ion chemical ionization mass spectrometry (NCI-MS). This paper investigates the potential of using gas chromatography (GC) with NCI-MS for the detection of SF6. The experimental parameters for an ultra-trace SF6 detection method utilizing minimal customizations of the analytical instrument are detailed. A method for the detection of parts per trillion (ppt) level concentrations of SF6 for the purpose of underground ventilation tracer gas analysis was successfully developed in this study. The method utilized a Shimadzu gas chromatography with negative ion chemical ionization mass spectrometry system equipped with an Agilent J&W HP-porous layer open tubular column coated with an alumina oxide (Al2O3) S column. The method detection limit (MDL) analysis as defined by the Environmental Protection Agency of the tracer data showed the method MDL to be 5.2 ppt.

  9. The application of gas chromatography/atmospheric pressure chemical ionisation time-of-flight mass spectrometry to impurity identification in Pharmaceutical Development.

    PubMed

    Bristow, Tony; Harrison, Mark; Sims, Martin

    2010-06-15

    Accurate mass measurement (used to determine elemental formulae) is an essential tool for impurity identification in pharmaceutical development for process understanding. Accurate mass liquid chromatography/mass spectrometry (LC/MS) is used widely for these types of analyses; however, there are still many occasions when gas chromatography (GC)/MS is the appropriate technique. Therefore, the provision of robust technology to provide accurate mass GC/MS (and GC/MS/MS) for this type of activity is essential. In this report we describe the optimisation and application of a newly available atmospheric pressure chemical ionisation (APCI) interface to couple GC to time-of-flight (TOF) MS.To fully test the potential of the new interface the APCI source conditions were optimised, using a number of standard compounds, with a variety of structures, as used in synthesis at AstraZeneca. These compounds were subsequently analysed by GC/APCI-TOF MS. This study was carried out to evaluate the range of compounds that are amenable to analysis using this technique. The range of compounds that can be detected and characterised using the technique was found to be extremely broad and include apolar hydrocarbons such as toluene. Both protonated molecules ([M + H](+)) and radical cations (M(+.)) were observed in the mass spectra produced by APCI, along with additional ion signals such as [M + H + O](+).The technique has been successfully applied to the identification of impurities in reaction mixtures from organic synthesis in process development. A typical mass accuracy of 1-2 mm/zunits (m/z 80-500) was achieved allowing the reaction impurities to be identified based on their elemental formulae. These results clearly demonstrate the potential of the technique as a tool for problem solving and process understanding in pharmaceutical development. The reaction mixtures were also analysed by GC/electron ionisation (EI)-MS and GC/chemical ionisation (CI)-MS to understand the capability of GC

  10. Processing Techniques and Applications of Silk Hydrogels in Bioengineering

    PubMed Central

    Floren, Michael; Migliaresi, Claudio; Motta, Antonella

    2016-01-01

    Hydrogels are an attractive class of tunable material platforms that, combined with their structural and functional likeness to biological environments, have a diversity of applications in bioengineering. Several polymers, natural and synthetic, can be used, the material selection being based on the required functional characteristics of the prepared hydrogels. Silk fibroin (SF) is an attractive natural polymer for its excellent processability, biocompatibility, controlled degradation, mechanical properties and tunable formats and a good candidate for the fabrication of hydrogels. Tremendous effort has been made to control the structural and functional characteristic of silk hydrogels, integrating novel biological features with advanced processing techniques, to develop the next generation of functional SF hydrogels. Here, we review the several processing methods developed to prepare advanced SF hydrogel formats, emphasizing a bottom-up approach beginning with critical structural characteristics of silk proteins and their behavior under specific gelation environments. Additionally, the preparation of SF hydrogel blends and other advanced formats will also be discussed. We conclude with a brief description of the attractive utility of SF hydrogels in relevant bioengineering applications. PMID:27649251

  11. Infrared band strengths: Laboratory techniques and applications to astronomical observations

    NASA Astrophysics Data System (ADS)

    Gerakines, P. A.

    2002-09-01

    Whenever an abundance measurement is derived by way of infrared spectroscopy, it will typically make use of a laboratory-obtained conversion factor between the size of an IR absorption feature and the (column) density of the molecule under study. This factor is usually called the "absolute absorption intensity" by a chemist or the "band strength" by a typical IR astronomer. Band strengths have been studied in chemistry since the 1950s, and the commonly quoted "accuracy to with a factor of ten" historically required of astronomical calculations has not required much new input into this area. Today, however, astronomical measurements require much higher precision, and it is time for IR astronomers to ask more of laboratory measurements and to understand when and why to use IR band strengths in a more appropriate manner. The history, interpretation, measurement, and common astrophysical applications of infrared band strengths will be discussed. The "secrets" of the laboratory techniques involved in their measurement are described, and a compilation of results from the literature is given along with some new results. Typical astrophysical applications and appropriate uses will also be discussed. Common misconceptions are confronted and two challenges are presented: (i) to the laboratory astrophysics community to produce and advertise accurate values with caveats when necessary, and (ii) to the observational community to use the most appropriate results for the environment under study.

  12. An integrated process for the recovery of high added-value compounds from olive oil using solid support free liquid-liquid extraction and chromatography techniques.

    PubMed

    Angelis, Apostolis; Hamzaoui, Mahmoud; Aligiannis, Nektarios; Nikou, Theodora; Michailidis, Dimitris; Gerolimatos, Panagiotis; Termentzi, Aikaterini; Hubert, Jane; Halabalaki, Maria; Renault, Jean-Hugues; Skaltsounis, Alexios-Léandros

    2017-03-31

    An integrated extraction and purification process for the direct recovery of high added value compounds from extra virgin olive oil (EVOO) is proposed by using solid support free liquid-liquid extraction and chromatography techniques. Two different extraction methods were developed on a laboratory-scale Centrifugal Partition Extractor (CPE): a sequential strategy consisting of several "extraction-recovery" cycles and a continuous strategy based on stationary phase co-current elution. In both cases, EVOO was used as mobile phase diluted in food grade n-hexane (feed mobile phase) and the required biphasic system was obtained by adding ethanol and water as polar solvents. For the sequential process, 17.5L of feed EVOO containing organic phase (i.e. 7L of EVOO treated) were extracted yielding 9.5g of total phenolic fraction corresponding to a productivity of 5.8g/h/L of CPE column. Regarding the second approach, the co-current process, 2L of the feed oil phase (containing to 0.8L of EVOO) were treated at 100mL/min yielding 1.03g of total phenolic fraction corresponding to a productivity of 8.9g/h/L of CPE column. The total phenolic fraction was then fractionated by using stepwise gradient elution Centrifugal Partition Chromatography (CPC). The biphasic solvent systems were composed of n-hexane, ethyl acetate, ethanol and water in different proportions (X/Y/2/3, v/v). In a single run of 4h on a column with a capacity of 1L, 910mg of oleocanthal, 882mg of oleacein, 104mg of hydroxytyrosol were successfully recovered from 5g of phenolic extract with purities of 85%, 92% and 90%, respectively. CPC fractions were then submitted to orthogonal chromatographic steps (adsorption on silica gel or size exclusion chromatography) leading to the isolation of additional eleven compounds belonging to triterpens, phenolic compounds and secoiridoids. Among them, elenolic acid ethylester was found to be new compound. Thin Layer Chromatography (TLC), Nuclear magnetic Resonance (NMR) and

  13. Multiplex gas chromatography

    NASA Technical Reports Server (NTRS)

    Valentin, Jose R.

    1990-01-01

    The principles of the multiplex gas chromatography (GC) technique, which is a possible candidate for chemical analysis of planetary atmospheres, are discussed. Particular attention is given to the chemical modulators developed by present investigators for multiplex GC, namely, the thermal-desorption, thermal-decomposition, and catalytic modulators, as well as to mechanical modulators. The basic technique of multiplex GC using chemical modulators and a mechanical modulator is demonstrated. It is shown that, with the chemical modulators, only one gas stream consisting of the carrier in combination with the components is being analyzed, resulting in a simplified instrument that requires relatively few consumables. The mechanical modulator demonstrated a direct application of multiplex GC for the analysis of gases in atmosphere of Titan at very low pressures.

  14. Multiplex gas chromatography

    NASA Technical Reports Server (NTRS)

    Valentin, Jose R.

    1990-01-01

    The principles of the multiplex gas chromatography (GC) technique, which is a possible candidate for chemical analysis of planetary atmospheres, are discussed. Particular attention is given to the chemical modulators developed by present investigators for multiplex GC, namely, the thermal-desorption, thermal-decomposition, and catalytic modulators, as well as to mechanical modulators. The basic technique of multiplex GC using chemical modulators and a mechanical modulator is demonstrated. It is shown that, with the chemical modulators, only one gas stream consisting of the carrier in combination with the components is being analyzed, resulting in a simplified instrument that requires relatively few consumables. The mechanical modulator demonstrated a direct application of multiplex GC for the analysis of gases in atmosphere of Titan at very low pressures.

  15. Standard-Setting Techniques: An Application for Counseling Programs.

    ERIC Educational Resources Information Center

    Stephenson, Agnes S.; Elmore, Patricia B.; Evans, John Andrew

    2000-01-01

    Standard-setting techniques concerning testing, comparisons of these techniques, and methods for assessing interrater and intrarater reliability are described. These techniques are discussed in relation to counselor education programs. (Author/MKA)

  16. Analytical Electrochemistry: Methodology and Applications of Dynamic Techniques.

    ERIC Educational Resources Information Center

    Heineman, William R.; Kissinger, Peter T.

    1980-01-01

    Reports developments involving the experimental aspects of finite and current analytical electrochemistry including electrode materials (97 cited references), hydrodynamic techniques (56), spectroelectrochemistry (62), stripping voltammetry (70), voltammetric techniques (27), polarographic techniques (59), and miscellany (12). (CS)

  17. Analytical Electrochemistry: Methodology and Applications of Dynamic Techniques.

    ERIC Educational Resources Information Center

    Heineman, William R.; Kissinger, Peter T.

    1980-01-01

    Reports developments involving the experimental aspects of finite and current analytical electrochemistry including electrode materials (97 cited references), hydrodynamic techniques (56), spectroelectrochemistry (62), stripping voltammetry (70), voltammetric techniques (27), polarographic techniques (59), and miscellany (12). (CS)

  18. Liquid chromatography-tandem mass spectrometry application, for the determination of extracellular hepatotoxins in Irish lake and drinking waters.

    PubMed

    Allis, Orla; Dauphard, Justine; Hamilton, Brett; Shuilleabhain, Aine Ni; Lehane, Mary; James, Kevin J; Furey, Ambrose

    2007-05-01

    A novel method for the determination of hepatotoxins; microcystins (MCs), and nodularin (Nod) in lake water and domestic chlorinated tap water has been developed using liquid chromatography hyphenated with electrospray ionization triple quadrupole mass spectrometry (LC-ESI-MS/MS). Optimization of the mass spectrometer parameters and mobile-phase composition was performed to maximize the sensitivity and reproducibility of the method. Detection of the hepatotoxins was carried out using multiple reaction monitoring experiments, thus improving the selectivity of the method. A total ion chromatogram and a precursor ion scan on ion m/z 135 was also applied to all samples to detect unknown microcystins or microcystins for which there are no standards available. A comprehensive validation of the LC-ESI-MS/MS method was completed that took into account matrix effects, specificity, linearity, accuracy, and precision. Good linear calibrations were obtained for MC-LR (1-200 microg/L; R2=0.9994) in spiked lake and tap water samples (1-50 microg/L; R2=0.9974). Acceptable interday repeatability was achieved for MC-LR in lake water with RSD values (n=9) ranging from 9.9 (10 microg/L) to 5.1% (100 microg/L). Excellent limits of detection (LOD) and limits of quantitation (LOQ) were achieved with spiked MCs and Nod samples; LOD=0.27 microg/L and LOQ=0.90 microg/L for MC-LR in the "normal linear range" and LOD=0.08 microg/L and LOQ=0.25 microg/L in the "low linear range" in both lake and chlorinated tap water. Similar results were obtained for a suite of microcystins and nodularin. This sensitive and rapid method does not require any sample preconcentration, including the elimination of solid-phase extraction (SPE) for the effective screening of hepatotoxins in water below the 1 microg/L WHO provisional guideline limit for MC-LR. Furthermore, SPE techniques are time-consuming, nonreproducible at trace levels, and offer poor recoveries with chlorinated water. The application of this LC

  19. Advanced proteomic liquid chromatography

    SciTech Connect

    Xie, Fang; Smith, Richard D.; Shen, Yufeng

    2012-10-26

    Liquid chromatography coupled with mass spectrometry is the predominant platform used to analyze proteomics samples consisting of large numbers of proteins and their proteolytic products (e.g., truncated polypeptides) and spanning a wide range of relative concentrations. This review provides an overview of advanced capillary liquid chromatography techniques and methodologies that greatly improve separation resolving power and proteomics analysis coverage, sensitivity, and throughput.

  20. Column Liquid Chromatography.

    ERIC Educational Resources Information Center

    Majors, Ronald E.; And Others

    1984-01-01

    Reviews literature covering developments of column liquid chromatography during 1982-83. Areas considered include: books and reviews; general theory; columns; instrumentation; detectors; automation and data handling; multidimensional chromatographic and column switching techniques; liquid-solid chromatography; normal bonded-phase, reversed-phase,…