Sample records for absorption spectrometry part

  1. [Determination of inorganic elements in different parts of Sonchus oleraceus L by flame atomic absorption spectrometry].

    PubMed

    Wang, Nai-Xing; Cui, Xue-Gui; Du, Ai-Qin; Mao, Hong-Zhi

    2007-06-01

    Flame atomic absorption spectrometry with air-acetylene flame was used for the determination of inorganic metal elements in different parts ( flower, leaf, stem and root) of Sonchus oleraceus L. The contents of Ca, Mg, K, Na, Fe, Mn, Cu, Zn, Cr, Co, Ni, Pb and Cd in the flower, leaf, stem and root of Sonchus oleraceus L were compared. The order from high to low of the additive weight (microg x g(-1)) for the 13 kinds of metal elements is as follows: leaf (77 213.72) > flower (47 927.15) > stem(42 280.99) > root (28 131.18). From the experimental results it was found that there were considerable differences in the contents of the metal elements in different parts, and there were richer contents of Fe, Zn, Mn and Cu in root and flower, which are necessary to human health, than in other parts.

  2. Absorption Mode FT-ICR Mass Spectrometry Imaging

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Smith, Donald F.; Kilgour, David P.; Konijnenburg, Marco

    2013-12-03

    Fourier transform ion cyclotron resonance mass spectrometry offers the highest mass resolving power for molecular imaging experiments. This high mass resolving power ensures that closely spaced peaks at the same nominal mass are resolved for proper image generation. Typically higher magnetic fields are used to increase mass resolving power. However, a gain in mass resolving power can also be realized by phase correction of the data for absorption mode display. In addition to mass resolving power, absorption mode offers higher mass accuracy and signal-to-noise ratio over the conventional magnitude mode. Here we present the first use of absorption mode formore » Fourier transform ion cyclotron resonance mass spectrometry imaging. The Autophaser algorithm is used to phase correct each spectrum (pixel) in the image and then these parameters are used by the Chameleon work-flow based data processing software to generate absorption mode ?Datacubes? for image and spectral viewing. Absorption mode reveals new mass and spatial features that are not resolved in magnitude mode and results in improved selected ion image contrast.« less

  3. Design considerations regarding an atomizer for multi-element electrothermal atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Katskov, Dmitri A.; Sadagov, Yuri M.

    2011-06-01

    The methodology of simultaneous multi-element electrothermal atomic absorption spectrometry (ETAAS-Electrothermal Atomic Absorption Spectrometry) stipulates rigid requirements to the design and operation of the atomizer. It must provide high degree of atomization for the group of analytes, invariant respective to the vaporization kinetics and heating ramp residence time of atoms in the absorption volume and absence of memory effects from major sample components. For the low resolution spectrometer with a continuum radiation source the reduced compared to traditional ETAAS (Electrothermal Atomic Absorption Spectrometry) sensitivity should be, at least partially, compensated by creating high density of atomic vapor in the absorption pulse. The sought-for characteristics were obtained for the 18 mm in length and 2.5 mm in internal diameter longitudinally heated graphite tube atomizer furnished with 2-4.5 mg of ring shaped carbon fiber yarn collector. The collector located next to the sampling port provides large substrate area that helps to keep the sample and its residue in the central part of the tube after drying. The collector also provides a "platform" effect that delays the vaporization and stipulates vapor release into absorption volume having already stabilized gas temperature. Due to the shape of external surface of the tube, presence of collector and rapid (about 10 °C/ms) heating, an inverse temperature distribution along the tube is attained at the beginnings of the atomization and cleaning steps. The effect is employed for cleaning of the atomizer using the set of short maximum power heating pulses. Preparation, optimal maintenance of the atomizer and its compliance to the multi-element determination requirements are evaluated and discussed. The experimental setup provides direct simultaneous determination of large group of element within 3-4 order concentration range. Limits of detection are close to those for sequential single element determination in

  4. Atomic Absorption, Atomic Fluorescence, and Flame Emission Spectrometry.

    ERIC Educational Resources Information Center

    Horlick, Gary

    1984-01-01

    This review is presented in six sections. Sections focus on literature related to: (1) developments in instrumentation, measurement techniques, and procedures; (2) performance studies of flames and electrothermal atomizers; (3) applications of atomic absorption spectrometry; (4) analytical comparisons; (5) atomic fluorescence spectrometry; and (6)…

  5. Simultaneous Atomic Absorption Spectrometry for Cadmium and Lead Determination in Wastewater: A Laboratory Exercise

    ERIC Educational Resources Information Center

    Correia, Paulo R. M.; Oliveira, Pedro V.

    2004-01-01

    The simultaneous determination of cadmium and lead by multi-element atomic absorption spectrometry with electrochemical atomization is proposed by employing a problem-based approach. The reports indicate that the students assimilated the principles of the simultaneous atomic absorption spectrometry (SIMAAS), the role of the chemical modifier, the…

  6. Bismuth as a general internal standard for lead in atomic absorption spectrometry.

    PubMed

    Bechlin, Marcos A; Fortunato, Felipe M; Ferreira, Edilene C; Gomes Neto, José A; Nóbrega, Joaquim A; Donati, George L; Jones, Bradley T

    2014-06-11

    Bismuth was evaluated as internal standard for Pb determination by line source flame atomic absorption spectrometry (LS FAAS), high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS) and line source graphite furnace atomic absorption spectrometry (LS GFAAS). Analysis of samples containing different matrices indicated close relationship between Pb and Bi absorbances. Correlation coefficients of calibration curves built up by plotting A(Pb)/A(Bi)versus Pb concentration were higher than 0.9953 (FAAS) and higher than 0.9993 (GFAAS). Recoveries of Pb improved from 52-118% (without IS) to 97-109% (IS, LS FAAS); 74-231% (without IS) to 96-109% (IS, HR-CS FAAS); and 36-125% (without IS) to 96-110% (IS, LS GFAAS). The relative standard deviations (n=12) were reduced from 0.6-9.2% (without IS) to 0.3-4.3% (IS, LS FAAS); 0.7-7.7% (without IS) to 0.1-4.0% (IS, HR-CS FAAS); and 2.1-13% (without IS) to 0.4-5.9% (IS, LS GFAAS). Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Determination of Cd in urine by cloud point extraction-tungsten coil atomic absorption spectrometry.

    PubMed

    Donati, George L; Pharr, Kathryn E; Calloway, Clifton P; Nóbrega, Joaquim A; Jones, Bradley T

    2008-09-15

    Cadmium concentrations in human urine are typically at or below the 1 microgL(-1) level, so only a handful of techniques may be appropriate for this application. These include sophisticated methods such as graphite furnace atomic absorption spectrometry and inductively coupled plasma mass spectrometry. While tungsten coil atomic absorption spectrometry is a simpler and less expensive technique, its practical detection limits often prohibit the detection of Cd in normal urine samples. In addition, the nature of the urine matrix often necessitates accurate background correction techniques, which would add expense and complexity to the tungsten coil instrument. This manuscript describes a cloud point extraction method that reduces matrix interference while preconcentrating Cd by a factor of 15. Ammonium pyrrolidinedithiocarbamate and Triton X-114 are used as complexing agent and surfactant, respectively, in the extraction procedure. Triton X-114 forms an extractant coacervate surfactant-rich phase that is denser than water, so the aqueous supernatant is easily removed leaving the metal-containing surfactant layer intact. A 25 microL aliquot of this preconcentrated sample is placed directly onto the tungsten coil for analysis. The cloud point extraction procedure allows for simple background correction based either on the measurement of absorption at a nearby wavelength, or measurement of absorption at a time in the atomization step immediately prior to the onset of the Cd signal. Seven human urine samples are analyzed by this technique and the results are compared to those found by the inductively coupled plasma mass spectrometry analysis of the same samples performed at a different institution. The limit of detection for Cd in urine is 5 ngL(-1) for cloud point extraction tungsten coil atomic absorption spectrometry. The accuracy of the method is determined with a standard reference material (toxic metals in freeze-dried urine) and the determined values agree with

  8. [Application of atomic absorption spectrometry in the engine knock detection].

    PubMed

    Chen, Li-Dan

    2013-02-01

    Because existing human experience diagnosis method and apparatus for auxiliary diagnosis method are difficult to diagnose quickly engine knock. Atomic absorption spectrometry was used to detect the automobile engine knock in in innovative way. After having determined Fe, Al, Cu, Cr and Pb content in the 35 groups of Audi A6 engine oil whose travel course is 2 000 -70 000 kilometers and whose sampling interval is 2 000 kilometers by atomic absorption spectrometry, the database of primary metal content in the same automobile engine at different mileage was established. The research shows that the main metal content fluctuates within a certain range. In practical engineering applications, after the determination of engine oil main metal content and comparison with its database value, it can not only help to diagnose the type and location of engine knock without the disintegration and reduce vehicle maintenance costs and improve the accuracy of engine knock fault diagnosis.

  9. Feasibility of high-resolution continuum source molecular absorption spectrometry in flame and furnace for sulphur determination in petroleum products

    NASA Astrophysics Data System (ADS)

    Kowalewska, Zofia

    2011-07-01

    For the first time, high-resolution molecular absorption spectrometry with a high-intensity xenon lamp as radiation source has been applied for the determination of sulphur in crude oil and petroleum products. The samples were analysed as xylene solutions using vaporisation in acetylene-air flame or in an electrothermally heated graphite furnace. The sensitive rotational lines of the CS molecule, belonging to the ∆ν = 0 vibrational sequence within the electronic transition X 1∑ + → A 1П, were applied. For graphite furnace molecular absorption spectrometry, the Pd + Mg organic modifier was selected. Strong interactions with Pd atoms enable easier decomposition of sulphur-containing compounds, likely through the temporal formation of Pd xS y molecules. At the 258.056 nm line, with the wavelength range covering central pixel ± 5 pixels and with application of interactive background correction, the detection limit was 14 ng in graphite furnace molecular absorption spectrometry and 18 mg kg -1 in flame molecular absorption spectrometry. Meanwhile, application of 2-points background correction found a characteristic mass of 12 ng in graphite furnace molecular absorption spectrometry and a characteristic concentration of 104 mg kg -1 in flame molecular absorption spectrometry. The range of application of the proposed methods turned out to be significantly limited by the properties of the sulphur compounds of interest. In the case of volatile sulphur compounds, which can be present in light petroleum products, severe difficulties were encountered. On the contrary, heavy oils and residues from distillation as well as crude oil could be analysed using both flame and graphite furnace vaporisation. The good accuracy of the proposed methods for these samples was confirmed by their mutual consistency and the results from analysis of reference samples (certified reference materials and home reference materials with sulphur content determined by X-ray fluorescence

  10. Diode laser differential absorption spectrometry for measurements of some parameters of condensed media.

    PubMed

    Liger, V V; Bolshov, M A; Kuritsyn, Yu A; Krivtsun, V M; Zybin, A V; Niemax, K

    2007-04-01

    A method of diode laser differential absorption spectrometry (DLDAS) is proposed. The method is based on the detection of absorption spectra variations caused by the changes of a parameter of a condensed media (temperature, composition of the components of a mixture, pH, etc.). Some simple theoretical background of the proposed technique is presented. The potentialities of the method are demonstrated in the experiments on remote contactless measurement of the temperature of aqueous solutions and measurement of the deviations of the composition of a mixture of dyes from the equilibrium state.

  11. COMPREHENSIVE ANALYSIS OF BIOLOGICALLY RELEVANT ARSENICALS BY PH-SELECTIVE HYDRIDE GENERATION-ATOMIC ABSORPTION SPECTROMETRY

    EPA Science Inventory


    A method based on pH-selective generation and separation of arsines is commonly used for analysis of inorganic, methylated, and dimethylated trivalent and pentavalent arsenicals by hydride generation-atomic absorption spectrometry (HG-AAS). We have optimized this method to pe...

  12. Accelerator mass spectrometry analysis of aroma compound absorption in plastic packaging materials

    NASA Astrophysics Data System (ADS)

    Stenström, Kristina; Erlandsson, Bengt; Hellborg, Ragnar; Wiebert, Anders; Skog, Göran; Nielsen, Tim

    1994-05-01

    Absorption of aroma compounds in plastic packaging materials may affect the taste of the packaged food and it may also change the quality of the packaging material. A method to determine the aroma compound absorption in polymers by accelerator mass spectrometry (AMS) is being developed at the Lund Pelletron AMS facility. The high sensitivity of the AMS method makes it possible to study these phenomena under realistic conditions. As a first test low density polyethylene exposed to 14C-doped ethyl acetate is examined. After converting the polymer samples with the absorbed aroma compounds to graphite, the {14C }/{13C } ratio of the samples is measured by the AMS system and the degree of aroma compound absorption is established. The results are compared with those obtained by supercritical fluid extraction coupled to gas chromatography (SFE-GC).

  13. DETERMINATION OF TOTAL MERCURY IN FISH TISSUES USING PYROLYSIS ATOMIC ABSORPTION SPECTROMETRY WITH GOLD AMALGAMATION

    EPA Science Inventory

    A simple and rapid procedure for measuring total mercury in fish tissues is evaluated and
    compared with conventional techniques. Using an automated instrument incorporating combustion, preconcentration by amalgamation with gold, and atomic absorption spectrometry (AAS), mill...

  14. Analysis of Dithiocarbamate Fungicides in Vegetable Matrices Using HPLC-UV Followed by Atomic Absorption Spectrometry.

    PubMed

    Al-Alam, Josephine; Bom, Laura; Chbani, Asma; Fajloun, Ziad; Millet, Maurice

    2017-04-01

    A simple method combining ion-pair methylation, high-performance liquid chromatography (HPLC) analysis with detection at 272 nm and atomic absorption spectrometry was developed in order to determine 10 dithiocarbamate fungicides (Dazomet, Metam-sodium, Ferbam, Ziram, Zineb, Maneb, Mancozeb, Metiram, Nabam and Propineb) and distinguish ethylenbisdithiocarbamates (EBDTCs) Zineb, Maneb and Mancozeb in diverse matrices. This method associates reverse phase analysis by HPLC analysis with detection at 272 nm, with atomic absorption spectrometry in order to distinguish, with the same extraction protocol, Maneb, Mancozeb and Zineb. The limits of detection (0.4, 0.8, 0.5, 1.25 and 1.97) and quantification (1.18, 2.5, 1.52, 4.2 and 6.52) calculated in injected nanogram, respectively, for Dazomet, Metam-Na, dimethyldithiocarbamates (DMDTCs), EBDTCs and propylenebisdithiocarbamates (PBDTCs) justify the sensitivity of the method used. The coefficients of determination R2 were 0.9985, 0.9978, 0.9949, 0.988 and 0.9794, respectively, for Dazomet, Metam-Na, DMDTCs, EBDTCs and PBDTCs, and the recovery from fortified apple and leek samples was above 90%. Results obtained with the atomic absorption method in comparison with spectrophotometric analysis focus on the importance of the atomic absorption as a complementary specific method for the distinction between different EBDTCs fungicides. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  15. Mass spectrometry of atmospheric aerosols--recent developments and applications. Part II: On-line mass spectrometry techniques.

    PubMed

    Pratt, Kerri A; Prather, Kimberly A

    2012-01-01

    Many of the significant advances in our understanding of atmospheric particles can be attributed to the application of mass spectrometry. Mass spectrometry provides high sensitivity with fast response time to probe chemically complex particles. This review focuses on recent developments and applications in the field of mass spectrometry of atmospheric aerosols. In Part II of this two-part review, we concentrate on real-time mass spectrometry techniques, which provide high time resolution for insight into brief events and diurnal changes while eliminating the potential artifacts acquired during long-term filter sampling. In particular, real-time mass spectrometry has been shown recently to provide the ability to probe the chemical composition of ambient individual particles <30 nm in diameter to further our understanding of how particles are formed through nucleation in the atmosphere. Further, transportable real-time mass spectrometry techniques are now used frequently on ground-, ship-, and aircraft-based studies around the globe to further our understanding of the spatial distribution of atmospheric aerosols. In addition, coupling aerosol mass spectrometry techniques with other measurements in series has allowed the in situ determination of chemically resolved particle effective density, refractive index, volatility, and cloud activation properties. Copyright © 2011 Wiley Periodicals, Inc.

  16. Determination of tetraalkyllead compounds in gasoline by liquid chromatography-atomic absorption spectrometry

    USGS Publications Warehouse

    Messman, J.D.; Rains, T.C.

    1981-01-01

    A liquid chromatography-atomic absorption spectrometry (LC-AAS) hybrid analytical technique is presented for metal speciation measurements on complex liquid samples. The versatility and inherent metal selectivity of the technique are Illustrated by the rapid determination of five tetraalkyllead compounds in commercial gasoline. Separation of the individual tetraalkyllead species is achieved by reversed-phase liquid chromatography using an acetonitrile/water mobile phase. The effluent from the liquid Chromatograph Is introduced directly into the aspiration uptake capillary of the nebulizer of an air/acetylene flame atomic absorption spectrometer. Spectral interferences due to coeluting hydrocarbon matrix constituents were not observed at the 283.3-nm resonance line of lead used for analysis. Detection limits of this LC-AAS hydrid analytical technique, based on a 20-??L injection, are approximately 10 ng Pb for each tetraalkyllead compound.

  17. Determination of mercury in hair: Comparison between gold amalgamation-atomic absorption spectrometry and mass spectrometry.

    PubMed

    Domanico, Francesco; Forte, Giovanni; Majorani, Costanza; Senofonte, Oreste; Petrucci, Francesco; Pezzi, Vincenzo; Alimonti, Alessandro

    2017-09-01

    Mercury is a heavy metal that causes serious health problems in exposed subjects. The most toxic form, i.e., methylmercury (MeHg), is mostly excreted through human hair. Numerous analytical methods are available for total Hg analysis in human hair, including cold vapour atomic fluorescence spectrometry (CV-AFS), inductively coupled plasma mass spectrometry (ICP-MS) and thermal decomposition amalgamation atomic absorption spectrometry (TDA-AAS). The aim of the study was to compare the TDA-AAS with the ICP-MS in the Hg quantification in human hair. After the washing procedure to minimize the external contamination, from each hair sample two aliquots were taken; the first was used for direct analysis of Hg by TDA-AAS and the second was digested for Hg determination by the ICP-MS. Results indicated that the two data sets were fully comparable (median; TDA-AAS, 475ngg -1 ; ICP-MS, 437ngg -1 ) and were not statistically different (Mann-Whitney test; p=0.44). The two techniques presented results with a good coefficient of correlation (r=0.94) despite different operative ranges and method limits. Both techniques satisfied internal performance requirements and the parameters for method validation resulting sensitive, precise and reliable. Finally, the use of the TDA-AAS can be considered instead of the ICP-MS in hair analysis in order to reduce sample manipulation with minor risk of contamination, less time consuming due to the absence of the digestion step and cheaper analyses. Copyright © 2016 Elsevier GmbH. All rights reserved.

  18. [Determination of mercury in Boletus impolitus by flow injection-atomic absorption spectrometry].

    PubMed

    Li, Tao; Wang, Yuan-Zhong

    2008-04-01

    Various test conditions and effect factors for the determination of mercury by flow injection-atomic absorption spectrometry were discussed, and a method for the determination of mercury in Boletus impolitus has been developed. The linear range for mercury is 0-60 microg x L(-1). The relative standard deviation is less than 3.0%, and the recovery is 96%-107%. This method is simple, rapid and has been applied to the determination of mercury in Boletus impolitus samples with satisfactory results.

  19. [Recent Development of Atomic Spectrometry in China].

    PubMed

    Xiao, Yuan-fang; Wang, Xiao-hua; Hang, Wei

    2015-09-01

    As an important part of modern analytical techniques, atomic spectrometry occupies a decisive status in the whole analytical field. The development of atomic spectrometry also reflects the continuous reform and innovation of analytical techniques. In the past fifteen years, atomic spectrometry has experienced rapid development and been applied widely in many fields in China. This review has witnessed its development and remarkable achievements. It contains several directions of atomic spectrometry, including atomic emission spectrometry (AES), atomic absorption spectrometry (AAS), atomic fluorescence spectrometry (AFS), X-ray fluorescence spectrometry (XRF), and atomic mass spectrometry (AMS). Emphasis is put on the innovation of the detection methods and their applications in related fields, including environmental samples, biological samples, food and beverage, and geological materials, etc. There is also a brief introduction to the hyphenated techniques utilized in atomic spectrometry. Finally, the prospects of atomic spectrometry in China have been forecasted.

  20. Liquid chromatography-hydride generation-atomic absorption spectrometry for the speciation of tin in seafoods.

    PubMed

    Viñas, Pilar; López-García, Ignacio; Merino-Meroño, Beatriz; Campillo, Natalia; Hernández-Cordóba, Manuel

    2004-04-01

    Liquid chromatography with hydride generation atomic absorption spectrometry as the detection system was applied to the separation and determination of inorganic tin, tributyltin, dibutyltin, monobutyltin, diphenyltin and monophenyltin. A reversed phase C18 column and a methanol/water/acetic acid (70:27:3, v/v/v) mixture containing 0.05%(v/v) triethylamine and 0.1%(w/v) tropolone as the mobile phase (isocratic elution) were used. Extraction of organotins from the samples was carried out using methanol containing 0.05%(w/v) tropolone, a process that was repeated twice. The supernatants were shaken with water and dichloromethane in a separating funnel and the organic phase was collected and evaporated to dryness. When the method was applied to the speciation of tin in fresh and canned mussels, no organotins above the detection limits were identified in any of the samples, inorganic tin being the only species detected. The reliability of the procedure was checked by analyzing the total tin content of the samples by electrothermal atomic absorption spectrometry and by speciation of tin in a certified reference material, mussel tissue (CRM 477). The method can be used for environmental monitoring of organotins contaminated samples.

  1. Cadmium, copper, lead, and zinc determination in precipitation: A comparison of inductively coupled plasma atomic emission spectrometry and graphite furnace atomization atomic absorption spectrometry

    USGS Publications Warehouse

    Reddy, M.M.; Benefiel, M.A.; Claassen, H.C.

    1987-01-01

    Selected trace element analysis for cadmium, copper, lead, and zinc in precipitation samples by inductively coupled plasma atomic emission Spectrometry (ICP) and by atomic absorption spectrometry with graphite furnace atomization (AAGF) have been evaluated. This task was conducted in conjunction with a longterm study of precipitation chemistry at high altitude sites located in remote areas of the southwestern United States. Coefficients of variation and recovery values were determined for a standard reference water sample for all metals examined for both techniques. At concentration levels less than 10 micrograms per liter AAGF analyses exhibited better precision and accuracy than ICP. Both methods appear to offer the potential for cost-effective analysis of trace metal ions in precipitation. ?? 1987 Springer-Verlag.

  2. Paleodiet characterisation of an Etrurian population of Pontecagnano (Italy) by Isotope Ratio Mass Spectrometry (IRMS) and Atomic Absorption Spectrometry (AAS)(#).

    PubMed

    Scarabino, Carla; Lubritto, Carmine; Proto, Antonio; Rubino, Mauro; Fiengo, Gilda; Marzaioli, Fabio; Passariello, Isabella; Busiello, Gaetano; Fortunato, Antonietta; Alfano, Davide; Sabbarese, Carlo; Rogalla, Detlef; De Cesare, Nicola; d'Onofrio, Antonio; Terrasi, Filippo

    2006-06-01

    Human bones recovered from the archaeological site of Pontecagnano (Salerno, Italy) have been studied to reconstruct the diet of an Etrurian population. Two different areas were investigated, named Library and Sant' Antonio, with a total of 44 tombs containing human skeletal remains, ranging in age from the 8th to the 3rd century B.C. This time span was confirmed by 14C dating obtained using Accelerator Mass Spectrometry (AMS) on one bone sample from each site. Atomic Absorption Spectrometry (AAS) was used to extract information about the concentration of Sr, Zn, Ca elements in the bone inorganic fraction, whilst stable isotope ratio measurements (IRMS) were carried out on bone collagen to obtain the delta13C and delta15N. A reliable technique has been used to extract and separate the inorganic and organic fractions of the bone remains. Both IRMS and AAS results suggest a mixed diet including C3 plant food and herbivore animals, consistent with archaeological indications.

  3. Noise-Immune Cavity-Enhanced Optical Heterodyne Molecular Spectrometry Modelling Under Saturated Absorption

    NASA Astrophysics Data System (ADS)

    Dupré, Patrick

    2015-06-01

    The Noise-Immune Cavity-Enhanced Optical Heterodyne Molecular Spectrometry (NICE-OHMS) is a modern technique renowned for its ultimate sensitivity, because it combines long equivalent absorption length provided by a high finesse cavity, and a detection theoretically limited by the sole photon-shot-noise. One fallout of the high finesse is the possibility to accumulating strong intracavity electromagnetic fields (EMF). Under this condition, molecular transitions can be easy saturated giving rise to the usual Lamb dips (or hole burning). However, the unusual shape of the basically trichromatic EMF (due to the RF lateral sidebands) induces nonlinear couplings, i.e., new crossover transitions. An analytical methodology will be presented to calculate spectra provided by NICE-OHMS experiments. It is based on the solutions of the equations of motion of an open two-blocked-level system performed in the frequency-domain (optically thin medium). Knowing the transition dipole moment, the NICE-OHMS signals (``absorption-like'' and ``dispersion-like'') can be simulated by integration over the Doppler shifts and by paying attention to the molecular Zeeman sublevels and to the EMF polarization The approach has been validated by discussion experimental data obtained on two transitions of {C2H2} in the near-infrared under moderated saturation. One of the applications of the saturated absorption is to be able to simultaneously determine the transition intensity and the density number while only one these 2 quantities can only be assessed in nonlinear absorption. J. Opt. Soc. Am. B 32, 838 (2015) Optics Express 16, 14689 (2008)

  4. Mass Spectrometry Imaging proves differential absorption profiles of well-characterised permeability markers along the crypt-villus axis.

    PubMed

    Nilsson, Anna; Peric, Alexandra; Strimfors, Marie; Goodwin, Richard J A; Hayes, Martin A; Andrén, Per E; Hilgendorf, Constanze

    2017-07-25

    Knowledge about the region-specific absorption profiles from the gastrointestinal tract of orally administered drugs is a critical factor guiding dosage form selection in drug development. We have used a novel approach to study three well-characterized permeability and absorption marker drugs in the intestine. Propranolol and metoprolol (highly permeable compounds) and atenolol (low-moderate permeability compound) were orally co-administered to rats. The site of drug absorption was revealed by high spatial resolution matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) and complemented by quantitative measurement of drug concentration in tissue homogenates. MALDI-MSI identified endogenous molecular markers that illustrated the villi structures and confirmed the different absorption sites assigned to histological landmarks for the three drugs. Propranolol and metoprolol showed a rapid absorption and shorter transit distance in contrast to atenolol, which was absorbed more slowly from more distal sites. This study provides novel insights into site specific absorption for each of the compounds along the crypt-villus axis, as well as confirming a proximal-distal absorption gradient along the intestine. The combined analytical approach allowed the quantification and spatial resolution of drug distribution in the intestine and provided experimental evidence for the suggested absorption behaviour of low and highly permeable compounds.

  5. [Evaluation of uncertainty for determination of tin and its compounds in air of workplace by flame atomic absorption spectrometry].

    PubMed

    Wei, Qiuning; Wei, Yuan; Liu, Fangfang; Ding, Yalei

    2015-10-01

    To investigate the method for uncertainty evaluation of determination of tin and its compounds in the air of workplace by flame atomic absorption spectrometry. The national occupational health standards, GBZ/T160.28-2004 and JJF1059-1999, were used to build a mathematical model of determination of tin and its compounds in the air of workplace and to calculate the components of uncertainty. In determination of tin and its compounds in the air of workplace using flame atomic absorption spectrometry, the uncertainty for the concentration of the standard solution, atomic absorption spectrophotometer, sample digestion, parallel determination, least square fitting of the calibration curve, and sample collection was 0.436%, 0.13%, 1.07%, 1.65%, 3.05%, and 2.89%, respectively. The combined uncertainty was 9.3%.The concentration of tin in the test sample was 0.132 mg/m³, and the expanded uncertainty for the measurement was 0.012 mg/m³ (K=2). The dominant uncertainty for determination of tin and its compounds in the air of workplace comes from least squares fitting of the calibration curve and sample collection. Quality control should be improved in the process of calibration curve fitting and sample collection.

  6. Mercury in Environmental and Biological Samples Using Online Combustion with Sequential Atomic Absorption and Fluorescence Measurements: A Direct Comparison of Two Fundamental Techniques in Spectrometry

    ERIC Educational Resources Information Center

    Cizdziel, James V.

    2011-01-01

    In this laboratory experiment, students quantitatively determine the concentration of an element (mercury) in an environmental or biological sample while comparing and contrasting the fundamental techniques of atomic absorption spectrometry (AAS) and atomic fluorescence spectrometry (AFS). A mercury analyzer based on sample combustion,…

  7. Determination of Chlorine in Milk via Molecular Absorption of SrCl Using High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry.

    PubMed

    Ozbek, Nil; Akman, Suleyman

    2016-07-20

    Total chlorine in milk was determined via the molecular absorption of diatomic strontium monochloride at 635.862 nm using high-resolution continuum source graphite furnace atomic absorption spectrometry. The effects of coating the graphite furnace, using different modifiers, amount of molecule-forming element, and different calibrants were investigated and optimized. Chlorine concentrations in milk samples were determined in a Zr-coated graphite furnace using 25 μg of Sr as the molecule-forming reagent and applying a pyrolysis temperature of 600 °C and a molecule-forming temperature of 2300 °C. Linearity was maintained up to 500 μg mL(-1) of Cl. The method was tested by analyzing a certified reference wastewater. The results were in the uncertainty limits of the certified value. The limit of detection of the method was 1.76 μg mL(-1). The chlorine concentrations in various cow milk samples taken from the market were found in the range of 588-1472 mg L(-1).

  8. Determination of selected elements in whole coal and in coal ash from the eight argonne premium coal samples by atomic absorption spectrometry, atomic emission spectrometry, and ion-selective electrode

    USGS Publications Warehouse

    Doughten, M.W.; Gillison, J.R.

    1990-01-01

    Methods for the determination of 24 elements in whole coal and coal ash by inductively coupled argon plasma-atomic emission spectrometry, flame, graphite furnace, and cold vapor atomic absorption spectrometry, and by ion-selective electrode are described. Coal ashes were analyzed in triplicate to determine the precision of the methods. Results of the analyses of NBS Standard Reference Materials 1633, 1633a, 1632a, and 1635 are reported. Accuracy of the methods is determined by comparison of the analysis of standard reference materials to their certified values as well as other values in the literature.

  9. Determination of gold in geologic materials by solvent extraction and atomic-absorption spectrometry

    USGS Publications Warehouse

    Huffman, Claude; Mensik, J.D.; Riley, L.B.

    1967-01-01

    The two methods presented for the determination of traces of gold in geologic materials are the cyanide atomic-absorption method and the fire-assay atomic-absorption method. In the cyanide method gold is leached with a sodium-cyanide solution. The monovalent gold is then oxidized to the trivalent state and concentrated by extracting into methyl isobutyl ketone prior to estimation by atomic absorption. In the fire-assay atomic-absorption method, the gold-silver bead obtained from fire assay is dissolved in nitric and hydrochloric acids. Gold is then concentrated by extracting into methyl isobutyl ketone prior to determination by atomic absorption. By either method concentrations as low as 50 parts per billion of gold can be determined in a 15-gram sample.

  10. Solid sampling determination of magnesium in lithium niobate crystals by graphite furnace atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Dravecz, Gabriella; Laczai, Nikoletta; Hajdara, Ivett; Bencs, László

    2016-12-01

    The vaporization/atomization processes of Mg in high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS-GFAAS) were investigated by evaporating solid (powder) samples of lithium niobate (LiNbO3) optical single crystals doped with various amounts of Mg in a transversally heated graphite atomizer (THGA). Optimal analytical conditions were attained by using the Mg I 215.4353 nm secondary spectral line. An optimal pyrolysis temperature of 1500 °C was found for Mg, while the compromise atomization temperature in THGAs (2400 °C) was applied for analyte vaporization. The calibration was performed against solid (powered) lithium niobate crystal standards. The standards were prepared with exactly known Mg content via solid state fusion of the oxide components of the matrix and analyte. The correlation coefficient (R value) of the linear calibration was not worse than 0.9992. The calibration curves were linear in the dopant concentration range of interest (0.74-7.25 mg/g Mg), when dosing 3-10 mg of the powder samples into the graphite sample insertion boats. The Mg content of the studied 19 samples was in the range of 1.69-4.13 mg/g. The precision of the method was better than 6.3%. The accuracy of the results was verified by means of flame atomic absorption spectrometry with solution sample introduction after digestion of several crystal samples.

  11. Measurements of sulfur compounds in CO 2 by diode laser atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Franzke, J.; Stancu, D. G.; Niemax, K.

    2003-07-01

    Two simple methods for the analysis of the total concentration of sulfur in CO 2 by diode laser atomic absorption spectrometry of excited, metastable sulfur atoms in a direct current discharge are presented. In the first method, the CO 2 sample gas is mixed with the plasma gas (Ar or He) while the second is based on reproducible measurements of the sulfur released from the walls in a helium discharge after being deposited as a result of operating the discharge in pure CO 2 sample gas. The detection limits obtained satisfy the requirements for the control of sulfur compounds in CO 2 used in the food and beverage industry.

  12. Speciation analysis of arsenic in biological matrices by automated hydride generation-cryotrapping-atomic absorption spectrometry with multiple microflame quartz tube atomizer (multiatomizer).

    EPA Science Inventory

    This paper describes an automated system for the oxidation state specific speciation of inorganic and methylated arsenicals by selective hydride generation - cryotrapping- gas chromatography - atomic absorption spectrometry with the multiatomizer. The corresponding arsines are ge...

  13. High purity polyimide analysis by solid sampling graphite furnace atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Santos, Rafael F.; Carvalho, Gabriel S.; Duarte, Fabio A.; Bolzan, Rodrigo C.; Flores, Erico M. M.

    2017-03-01

    In this work, Cr, Cu, Mn, Na and Ni were determined in high purity polyimides (99.5%) by solid sampling graphite furnace atomic absorption spectrometry (SS-GFAAS) using Zeeman effect background correction system with variable magnetic field, making possible the simultaneous measurement at high or low sensitivity. The following analytical parameters were evaluated: pyrolysis and atomization temperatures, feasibility of calibration with aqueous solution, linear calibration range, sample mass range and the use of chemical modifier. Calibration with aqueous standard solutions was feasible for all analytes. No under or overestimated results were observed and up to 10 mg sample could be introduced on the platform for the determination of Cr, Cu, Mn, Na and Ni. The relative standard deviation ranged from 3 to 20%. The limits of detection (LODs) achieved using the high sensitivity mode were as low as 7.0, 2.5, 1.7, 17 and 0.12 ng g- 1 for Cr, Cu, Mn, Na and Ni, respectively. No addition of chemical modifier was necessary, except for Mn determination where Pd was required. The accuracy was evaluated by analyte spike and by comparison of the results with those obtained by inductively coupled plasma optical emission spectrometry and inductively coupled plasma mass spectrometry after microwave-assisted digestion in a single reaction chamber system and also by neutron activation analysis. No difference among the results obtained by SS-GFAAS and those obtained by alternative analytical methods using independent techniques. SS-GFAAS method showed some advantages, such as the determination of metallic contaminants in high purity polyimides with practically no sample preparation, very low LODs, calibration with aqueous standards and determination in a wide range of concentration.

  14. Comparison of two methods for blood lead analysis in cattle: graphite-furnace atomic absorption spectrometry and LeadCare(R) II system.

    PubMed

    Bischoff, Karyn; Gaskill, Cynthia; Erb, Hollis N; Ebel, Joseph G; Hillebrandt, Joseph

    2010-09-01

    The current study compared the LeadCare(R) II test kit system with graphite-furnace atomic absorption spectrometry for blood lead (Pb) analysis in 56 cattle accidentally exposed to Pb in the field. Blood Pb concentrations were determined by LeadCare II within 4 hr of collection and after 72 hr of refrigeration. Blood Pb concentrations were determined by atomic absorption spectrometry, and samples that were coagulated (n = 12) were homogenized before analysis. There was strong rank correlation (R(2) = 0.96) between atomic absorption and LeadCare II (within 4 hr of collection), and a conversion formula was determined for values within the observed range (3-91 mcg/dl, although few had values >40 mcg/dl). Median and mean blood pb concentrations for atomic absorption were 7.7 and 15.9 mcg/dl, respectively; for LeadCare II, medians were 5.2 mcg/dl at 4 hr and 4.9 mcg/dl at 72 hr, and means were 12.4 and 11.7, respectively. LeadCare II results at 4 hr strongly correlated with 72 hr results (R(2) = 0.96), but results at 72 hr were lower (P < 0.01). There was no significant difference between coagulated and uncoagulated samples run by atomic absorption. Although there have been several articles that compared LeadCare with other analytical techniques, all were for the original system, not LeadCare II. The present study indicated that LeadCare II results correlated well with atomic absorption over a wide range of blood Pb concentrations and that refrigerating samples for up to 72 hr before LeadCare II analysis was acceptable for clinical purposes.

  15. Automation of preparation of nonmetallic samples for analysis by atomic absorption and inductively coupled plasma spectrometry

    NASA Technical Reports Server (NTRS)

    Wittmann, A.; Willay, G.

    1986-01-01

    For a rapid preparation of solutions intended for analysis by inductively coupled plasma emission spectrometry or atomic absorption spectrometry, an automatic device called Plasmasol was developed. This apparatus used the property of nonwettability of glassy C to fuse the sample in an appropriate flux. The sample-flux mixture is placed in a composite crucible, then heated at high temperature, swirled until full dissolution is achieved, and then poured into a water-filled beaker. After acid addition, dissolution of the melt, and filling to the mark, the solution is ready for analysis. The analytical results obtained, either for oxide samples or for prereduced iron ores show that the solutions prepared with this device are undistinguished from those obtained by manual dissolutions done by acid digestion or by high temperature fusion. Preparation reproducibility and analytical tests illustrate the performance of Plasmasol.

  16. Validation of an analytical method based on the high-resolution continuum source flame atomic absorption spectrometry for the fast-sequential determination of several hazardous/priority hazardous metals in soil.

    PubMed

    Frentiu, Tiberiu; Ponta, Michaela; Hategan, Raluca

    2013-03-01

    The aim of this paper was the validation of a new analytical method based on the high-resolution continuum source flame atomic absorption spectrometry for the fast-sequential determination of several hazardous/priority hazardous metals (Ag, Cd, Co, Cr, Cu, Ni, Pb and Zn) in soil after microwave assisted digestion in aqua regia. Determinations were performed on the ContrAA 300 (Analytik Jena) air-acetylene flame spectrometer equipped with xenon short-arc lamp as a continuum radiation source for all elements, double monochromator consisting of a prism pre-monocromator and an echelle grating monochromator, and charge coupled device as detector. For validation a method-performance study was conducted involving the establishment of the analytical performance of the new method (limits of detection and quantification, precision and accuracy). Moreover, the Bland and Altman statistical method was used in analyzing the agreement between the proposed assay and inductively coupled plasma optical emission spectrometry as standardized method for the multielemental determination in soil. The limits of detection in soil sample (3σ criterion) in the high-resolution continuum source flame atomic absorption spectrometry method were (mg/kg): 0.18 (Ag), 0.14 (Cd), 0.36 (Co), 0.25 (Cr), 0.09 (Cu), 1.0 (Ni), 1.4 (Pb) and 0.18 (Zn), close to those in inductively coupled plasma optical emission spectrometry: 0.12 (Ag), 0.05 (Cd), 0.15 (Co), 1.4 (Cr), 0.15 (Cu), 2.5 (Ni), 2.5 (Pb) and 0.04 (Zn). Accuracy was checked by analyzing 4 certified reference materials and a good agreement for 95% confidence interval was found in both methods, with recoveries in the range of 94-106% in atomic absorption and 97-103% in optical emission. Repeatability found by analyzing real soil samples was in the range 1.6-5.2% in atomic absorption, similar with that of 1.9-6.1% in optical emission spectrometry. The Bland and Altman method showed no statistical significant difference between the two spectrometric

  17. The role of atomic absorption spectrometry in geochemical exploration

    USGS Publications Warehouse

    Viets, J.G.; O'Leary, R. M.

    1992-01-01

    In this paper we briefly describe the principles of atomic absorption spectrometry (AAS) and the basic hardware components necessary to make measurements of analyte concentrations. Then we discuss a variety of methods that have been developed for the introduction of analyte atoms into the light path of the spectrophotometer. This section deals with sample digestion, elimination of interferences, and optimum production of ground-state atoms, all critical considerations when choosing an AAS method. Other critical considerations are cost, speed, simplicity, precision, and applicability of the method to the wide range of materials sampled in geochemical exploration. We cannot attempt to review all of the AAS methods developed for geological materials but instead will restrict our discussion to some of those appropriate for geochemical exploration. Our background and familiarity are reflected in the methods we discuss, and we have no doubt overlooked many good methods. Our discussion should therefore be considered a starting point in finding the right method for the problem, rather than the end of the search. Finally, we discuss the future of AAS relative to other instrumental techniques and the promising new directions for AAS in geochemical exploration. ?? 1992.

  18. Antibiotic toxicity and absorption in zebrafish using liquid chromatography-tandem mass spectrometry.

    PubMed

    Zhang, Fan; Qin, Wei; Zhang, Jing-Pu; Hu, Chang-Qin

    2015-01-01

    Evaluation of drug toxicity is necessary for drug safety, but in vivo drug absorption is varied; therefore, a rapid, sensitive and reliable method for measuring drugs is needed. Zebrafish are acceptable drug toxicity screening models; we used these animals with a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method in a multiple reaction monitoring mode to quantify drug uptake in zebrafish to better estimate drug toxicity. Analytes were recovered from zebrafish homogenate by collecting supernatant. Measurements were confirmed for drugs in the range of 10-1,000 ng/mL. Four antibiotics with different polarities were tested to explore any correlation of drug polarity, absorption, and toxicity. Zebrafish at 3 days post-fertilization (dpf) absorbed more drug than those at 6 h post-fertilization (hpf), and different developmental periods appeared to be differentially sensitive to the same compound. By observing abnormal embryos and LD50 values, zebrafish embryos at 6 hpf were considered to be suitable for evaluating embryotoxicity. Also, larvae at 3 dpf were adapted to measure acute drug toxicity in adult mammals. Thus, we can exploit zebrafish to study drug toxicity and can reliably quantify drug uptake with LC-MS/MS. This approach will be helpful for future studies of toxicology in zebrafish.

  19. Liquid-phase microextraction combined with graphite furnace atomic absorption spectrometry: A review.

    PubMed

    de la Calle, Inmaculada; Pena-Pereira, Francisco; Lavilla, Isela; Bendicho, Carlos

    2016-09-14

    An overview of the combination of liquid-phase microextraction (LPME) techniques with graphite furnace atomic absorption spectrometry (GFAAS) is reported herein. The high sensitivity of GFAAS is significantly enhanced by its association with a variety of miniaturized solvent extraction approaches. LPME-GFAAS thus represents a powerful combination for determination of metals, metalloids and organometallic compounds at (ultra)trace level. Different LPME modes used with GFAAS are briefly described, and the experimental parameters that show an impact in those microextraction processes are discussed. Special attention is paid to those parameters affecting GFAAS analysis. Main issues found when coupling LPME and GFAAS, as well as those strategies reported in the literature to solve them, are summarized. Relevant applications published on the topic so far are included. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Quantification of the fluorine containing drug 5-fluorouracil in cancer cells by GaF molecular absorption via high-resolution continuum source molecular absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Krüger, Magnus; Huang, Mao-Dong; Becker-Roß, Helmut; Florek, Stefan; Ott, Ingo; Gust, Ronald

    The development of high-resolution continuum source molecular absorption spectrometry made the quantification of fluorine feasible by measuring the molecular absorption as gallium monofluoride (GaF). Using this new technique, we developed on the example of 5-fluorouracil (5-FU) a graphite furnace method to quantify fluorine in organic molecules. The effect of 5-FU on the generation of the diatomic GaF molecule was investigated. The experimental conditions such as gallium nitrate amount, temperature program, interfering anions (represented as corresponding acids) and calibration for the determination of 5-FU in standard solution and in cellular matrix samples were investigated and optimized. The sample matrix showed no effect on the sensitivity of GaF molecular absorption. A simple calibration curve using an inorganic sodium fluoride solution can conveniently be used for the calibration. The described method is sensitive and the achievable limit of detection is 0.23 ng of 5-FU. In order to establish the concept of "fluorine as a probe in medicinal chemistry" an exemplary application was selected, in which the developed method was successfully demonstrated by performing cellular uptake studies of the 5-FU in human colon carcinoma cells.

  1. Determination of Sodium, Potassium, Magnesium, and Calcium Minerals Level in Fresh and Boiled Broccoli and Cauliflower by Atomic Absorption Spectrometry

    NASA Astrophysics Data System (ADS)

    Nerdy

    2018-01-01

    Vegetables from the cabbage family vegetables consumed by many people, which is known healthful, by eaten raw, boiled, or cooked (stir fry or soup). Vegetables like broccoli and cauliflower contain vitamins, minerals, and fiber. This study aims to determine the decrease percentage of sodium, potassium, magnesium, and calcium minerals level caused by boiled broccoli and cauliflower by atomic absorption spectrometry. Boiled broccoli and cauliflower prepared by given boiled treatment in boiling water for 3 minutes. Fresh and boiled broccoli and cauliflower carried out dry destruction, followed by quantitative analysis of sodium, potassium, magnesium, and calcium minerals respectively at a wavelength of 589.0 nm; 766.5 nm; 285.2 nm; and 422.7 nm, using atomic absorption spectrometry methods. After the determination of the sodium, potassium, magnesium, and calcium minerals level followed by validation of analytical methods with accuracy, precision, linearity, range, limit of detection (LOD), and limit of quantitation (LOQ) parameters. Research results show a decrease in the sodium, potassium, magnesium, and calcium minerals level in boiled broccoli and cauliflower compared with fresh broccoli and cauliflower. Validation of analytical methods gives results that spectrometry methods used for determining sodium, potassium, magnesium, and calcium minerals level are valid. It concluded that the boiled gives the effect of decreasing the minerals level significantly in broccoli and cauliflower.

  2. [Determination of eight trace elements in the Swertia davidii Franch by flame atomic absorption spectrometry].

    PubMed

    Li, Tao; Wang, Yuan-zhong; Yu, Hon; Cao, Yu-juan; Zhang, Jing-jing; Liu, Qin

    2007-12-01

    The effects of different sample digestives on the determination of Swertia davidii Franch are compared. Eight trace elements in the Swertia davidii Franch were determined by flame atomic absorption spectrometry. The result shows that the RSD and recovery are better if the Swertia davidii Franch was digested with HNO3-HClO4 (5 : 1) mixed acid. The experimental results show that the detection limits were all smaller than 0.097 microg x mL(-1), the RSDs (n=8) all smaller than 2.34%, and the addition standard recovery (ASR) (n=8) was 89.32%-106.65% for all the elements.

  3. Determination of cadmium and lead at low levels by using preconcentration at fullerene coupled to thermospray flame furnace atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Pereira, M. G.; Pereira-Filho, E. R.; Berndt, H.; Arruda, M. A. Z.

    2004-04-01

    A new and sensitive method for Cd and Pb determinations, based on the coupling of thermospray flame furnace atomic absorption spectrometry and a preconcentrator system, was developed. The procedure comprised the chelating of Cd and Pb with ammonium pyrrolidinedithiocarbamate with posterior adsorption of the chelates on a mixture (40 mg) of C 60 and C 70 at a flow rate of 2.0 ml min -1. These chelates were eluted from the adsorbent by passing a continuous flow of ethanol (80% v/v) at 0.9 ml min -1 to a nickel tube placed in an air/acetylene flame. After sample introduction into the tube by using a ceramic capillary (0.5 mm i.d.), the analytical signals were registered as peak height. Under these conditions, improvement factors in detectability of 675 and 200 were obtained for Cd and Pb, respectively, when compared to conventional flame atomic absorption spectrometry. Spiked samples (mineral and tap waters) and drinking water containing natural concentrations of Cd were employed for evaluating accuracy by comparing the results obtained from the proposed methodology with those using electrothermal atomic absorption spectrometry. In addition, certified reference materials (rye grass, CRM 281 and pig kidney, CRM 186) were also adopted for the accuracy tests. Due to the good linearity ranges for Cd (0.5-5.0 μg l -1) and Pb (10-250 μg l -1), samples with different concentrations could be analyzed. Detection limits of 0.1 and 2.4 μg l -1 were obtained for Cd and Pb, respectively, and RSD values <4.5% were observed ( n=10). Finally, a sample throughput of 24 determinations per hour was possible.

  4. Validation of an analytical method based on the high-resolution continuum source flame atomic absorption spectrometry for the fast-sequential determination of several hazardous/priority hazardous metals in soil

    PubMed Central

    2013-01-01

    Background The aim of this paper was the validation of a new analytical method based on the high-resolution continuum source flame atomic absorption spectrometry for the fast-sequential determination of several hazardous/priority hazardous metals (Ag, Cd, Co, Cr, Cu, Ni, Pb and Zn) in soil after microwave assisted digestion in aqua regia. Determinations were performed on the ContrAA 300 (Analytik Jena) air-acetylene flame spectrometer equipped with xenon short-arc lamp as a continuum radiation source for all elements, double monochromator consisting of a prism pre-monocromator and an echelle grating monochromator, and charge coupled device as detector. For validation a method-performance study was conducted involving the establishment of the analytical performance of the new method (limits of detection and quantification, precision and accuracy). Moreover, the Bland and Altman statistical method was used in analyzing the agreement between the proposed assay and inductively coupled plasma optical emission spectrometry as standardized method for the multielemental determination in soil. Results The limits of detection in soil sample (3σ criterion) in the high-resolution continuum source flame atomic absorption spectrometry method were (mg/kg): 0.18 (Ag), 0.14 (Cd), 0.36 (Co), 0.25 (Cr), 0.09 (Cu), 1.0 (Ni), 1.4 (Pb) and 0.18 (Zn), close to those in inductively coupled plasma optical emission spectrometry: 0.12 (Ag), 0.05 (Cd), 0.15 (Co), 1.4 (Cr), 0.15 (Cu), 2.5 (Ni), 2.5 (Pb) and 0.04 (Zn). Accuracy was checked by analyzing 4 certified reference materials and a good agreement for 95% confidence interval was found in both methods, with recoveries in the range of 94–106% in atomic absorption and 97–103% in optical emission. Repeatability found by analyzing real soil samples was in the range 1.6–5.2% in atomic absorption, similar with that of 1.9–6.1% in optical emission spectrometry. The Bland and Altman method showed no statistical significant difference

  5. Determination of gold in copper-bearing sulphide ores and metallurgical flotation products by atomic-absorption spectrometry.

    PubMed

    Strong, B; Murray-Smith, R

    1974-12-01

    A method is described which is specific for the determination of gold in sulphide copper ores and concentrates. Direct decomposition with aqua regia was found to be incomplete. A carefully controlled roasting stage followed by treatment with hydrochloric acid and then aqua regia was effective for dissolving all the gold. The gold is extracted into 4-methylpentan-2-one (methyli-sobutylketone) then aspirated into a very lean air-acetylene flame and the gold determined by atomic-absorption spectrometry. No interferences were observed from large concentrations of copper, iron or nickel.

  6. Flow injection analysis-flame atomic absorption spectrometry system for indirect determination of sulfite after on-line reduction of solid-phase manganese (IV) dioxide reactor.

    PubMed

    Zare-Dorabei, Rouholah; Boroun, Shokoufeh; Noroozifar, Meissam

    2018-02-01

    A new and simple flow injection method followed by atomic absorption spectrometry was developed for indirect determination of sulfite. The proposed method is based on the oxidation of sulfite to sulphate ion using solid-phase manganese dioxide (30% W/W suspended on silica gel beads) reactor. MnO 2 will be reduced to Mn(II) by sample injection in to the column under acidic carrier stream of HNO 3 (pH 2) with flow rate of 3.5mLmin -1 at room temperature. Absorption measurement of Mn(II) which is proportional to the concentration of sulfite in the sample was carried out by atomic absorption spectrometry. The calibration curve was linear up to 25mgL -1 with a detection limit (DL) of 0.08mgL -1 for 400µL injection sample volume. The presented method is efficient toward sulfite determination in sugar and water samples with a relative standard deviation (RSD) less than 1.2% and a sampling rate of about 60h -1 . Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Application of thermospray flame furnace atomic absorption spectrometry for investigation of silver nanoparticles.

    PubMed

    Sirirat, Natnicha; Tetbuntad, Kornrawee; Siripinyanond, Atitaya

    2017-03-01

    Thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) was applied to investigate the time-dependent absorption peak profile of various forms of silver. The thermospray flame furnace was set up with a 10-cm-long nickel tube with six holes, each 2.0 mm in diameter, to allow the flame to enter, and this nickel tube acted as a furnace. A sample of 300 μL was introduced into this furnace by use of water as a carrier at a flow rate of 0.5 mL min -1 through the ceramic capillary (0.5-mm inner diameter and 2.0-mm outer diameter), which was inserted into the front hole of the nickel tube. The system was applied to examine atomization behaviors of silver nanoparticles (AgNPs) with particle sizes ranging from 10 to 100 nm. The atomization rate of AgNPs was faster than that of the dissolved silver ion. With increased amount of silver, the decay time observed from the time-dependent absorption peak profile was shortened in the case of dissolved silver ion, but it was increased in the case of AgNPs. With the particle size ranging from 10 to 100 nm, the detection sensitivity was indirectly proportional to the particle size, suggesting that TS-FF-AAS may offer insights into the particle size of AgNPs provided that the concentration of the silver is known. To obtain quantitative information on AgNPs, acid dissolution of the particles was performed before TS-FF-AAS analysis, and recoveries of 80-110% were obtained.

  8. [Determination of trace gallium by graphite furnace atomic absorption spectrometry in urine].

    PubMed

    Zhou, L Z; Fu, S; Gao, S Q; He, G W

    2016-06-20

    To establish a method for determination trace gallium in urine by graphite furnace atomic absorption spectrometry (GFAAS). The ammonium dihydrogen phosphate was matrix modifier. The temperature effect about pyrolysis (Tpyr) and atomization temperature were optimized for determination of trace gallium. The method of technical standard about within-run, between-run and recoveries of standard were optimized. The method showed a linear relationship within the range of 0.20~80.00 μg/L (r=0.998). The within-run and between-run relative standard deviations (RSD) of repetitive measurement at 5.0, 10.0, 20.0 μg/L concentration levels were 2.1%~5.5% and 2.3%~3.0%. The detection limit was 0.06 μg/L. The recoveries of gallium were 98.2%~101.1%. This method is simple, low detection limit, accurate, reliable and reproducible. It has been applied for determination of trace gallium in urine samples those who need occupation health examination or poisoning diagnosis.

  9. Lead concentrations and isotope ratios in street dust determined by electrothermal atomic absorption spectrometry and inductively coupled plasma mass spectrometry.

    PubMed

    Nageotte, S M; Day, J P

    1998-01-01

    A major source of environmental lead, particularly in urban areas, has been from the combustion of leaded petrol. Street dust has previously been used to assess urban lead contamination, and the dust itself can also be a potential source of lead ingestion, particularly to children. The progressive reduction of lead in petrol, in recent years, would be expected to have been reflected in a reduction of lead in urban dust. We have tested this hypothesis by repeating an earlier survey of Manchester street dust and carrying out a comparable survey in Paris. Samples were collected from streets and parks, lead was extracted by digestion with concentrated nitric acid and determined by electrothermal atomic absorption spectrometry. Lead isotope ratios were measured by inductively coupled plasma mass spectrometry. Results for Manchester show that lead concentrations have fallen by about 40% (street dust averages, 941 micrograms g-1 (ppm) in 1975 down to 569 ppm in 1997). In Paris, the lead levels in street dust are much higher and significant differences were observed between types of street (not seen in Manchester). Additionally, lead levels in parks were much lower than in Manchester. Samples collected under the Eiffel Tower had very high concentrations and lead isotope ratios showed that this was unlikely to be fallout from motor vehicles but could be due to the paint used on the tower. Isotope ratios measurements also revealed that lead additives used in France and the UK come from different sources.

  10. Investigating effects of sample pretreatment on protein stability using size-exclusion chromatography and high-resolution continuum source atomic absorption spectrometry.

    PubMed

    Rakow, Tobias; El Deeb, Sami; Hahne, Thomas; El-Hady, Deia Abd; AlBishri, Hassan M; Wätzig, Hermann

    2014-09-01

    In this study, size-exclusion chromatography and high-resolution atomic absorption spectrometry methods have been developed and evaluated to test the stability of proteins during sample pretreatment. This especially includes different storage conditions but also adsorption before or even during the chromatographic process. For the development of the size exclusion method, a Biosep S3000 5 μm column was used for investigating a series of representative model proteins, namely bovine serum albumin, ovalbumin, monoclonal immunoglobulin G antibody, and myoglobin. Ambient temperature storage was found to be harmful to all model proteins, whereas short-term storage up to 14 days could be done in an ordinary refrigerator. Freezing the protein solutions was always complicated and had to be evaluated for each protein in the corresponding solvent. To keep the proteins in their native state a gentle freezing temperature should be chosen, hence liquid nitrogen should be avoided. Furthermore, a high-resolution continuum source atomic absorption spectrometry method was developed to observe the adsorption of proteins on container material and chromatographic columns. Adsorption to any container led to a sample loss and lowered the recovery rates. During the pretreatment and high-performance size-exclusion chromatography, adsorption caused sample losses of up to 33%. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Interference of nitrite and nitrogen dioxide on mercury and selenium determination by chemical vapor generation atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Nunes, Dayana Lopes; dos Santos, Eliane Pereira; Barin, Juliano Smanioto; Mortari, Sergio Roberto; Dressler, Valderi Luiz; de Moraes Flores, Érico Marlon

    2005-06-01

    In this study, a systematic investigation was performed concerning the interference of nitrogen oxides on the determination of selenium and mercury by hydride generation atomic absorption spectrometry (HG AAS) and cold vapor atomic absorption spectrometry (CV AAS). The effect of nitrate, nitrite and NO 2 dissolved in the condensed phase was evaluated. No effect of NO 3- on Se and Hg determination was observed up to 100 mg of sodium nitrate added to the reaction vessel. The Se signal was reduced by about 80% upon the addition of 6.8 mg NO 2-. For Hg, no interference of nitrite was observed up to 20 mg of NO 2-. A complete suppression of the Se signal was observed when gaseous NO 2 was introduced into analytical solutions. For Hg, a signal decrease between 8 and 13% occurred. For Se, bubbling argon or heating the solution was not able to recover the original absorbance values, whereas Hg signals were recovered with these procedures. When gaseous NO 2 was passed directly into the atomizer, Se signals decreased similarly to when NO 2 was bubbled in analytical solutions. The addition of urea, hydroxylamine hydrochloride and sulfamic acid (SA) was investigated to reduce the NO 2 effect in sample digests containing residual NO 2, but only SA was effective in reducing the interference. Based on the results, it is possible to propose the use of SA to prevent interferences in Se and Hg determinations by HG AAS and CV AAS, respectively.

  12. Determination of trace amount of cadmium using dispersive liquid-liquid microextraction-slotted quartz tube-flame atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Fırat, Merve; Bakırdere, Sezgin; Fındıkoğlu, Maral Selin; Kafa, Emine Betül; Yazıcı, Elif; Yolcu, Melda; Büyükpınar, Çağdaş; Chormey, Dotse Selali; Sel, Sabriye; Turak, Fatma

    2017-03-01

    This study was performed to develop a sensitive analytical method for the determination of cadmium by slotted quartz tube-flame atomic absorption spectrometry (SQT-FAAS) after dispersive liquid-liquid microextraction (DLLME). The parameters affecting the cadmium complex formation and its extraction output were optimized to obtain high extraction efficiency. These included the pH and amount of the buffer solution, and the concentration of the ligand. The DLLME method was comprehensively optimized based on the type and amount of extraction solvent, dispersive solvent and salt. The type and period of mixing needed for a more effective extraction was also investigated. In order to further improve the sensitivity for the determination of cadmium, the flame atomic absorption spectrometry was fitted with a slotted quartz tube to increase the residence time of cadmium atoms in the pathway of incident light from a hollow cathode lamp. The limits of detection and quantitation (LOD and LOQ) for the FAAS were found to be 42 and 140 μg L- 1, respectively. Under the optimum conditions, LOD and LOQ of the FAAS after DLLME were calculated as 1.3 and 4.4 μg L- 1, respectively. Combining both optimized parameters of the DLLME and SQT-FAAS gave 0.5 and 1.5 μg L- 1 as LOD and LOQ, respectively. Accuracy of the method was also checked using a wastewater certified reference material (EU-L-2), and the result was in good agreement with the certified value.

  13. Ultrasensitive determination of cadmium in seawater by hollow fiber supported liquid membrane extraction coupled with graphite furnace atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Peng, Jin-feng; Liu, Rui; Liu, Jing-fu; He, Bin; Hu, Xia-lin; Jiang, Gui-bin

    2007-05-01

    A new procedure, based on hollow fiber supported liquid membrane preconcentration coupled with graphite furnace atomic absorption spectrometry (GFAAS) detection, was developed for the determination of trace Cd in seawater samples. With 1-octanol that contained a mixture of dithizone (carrier) and oleic acid immobilized in the pores of the polypropylene hollow fiber as a liquid membrane, Cd was selectively extracted from water samples into 0.05 M HNO 3 that filled the lumen of the hollow fiber as a stripping solution. The main extraction related parameters were optimized, and the effects of salinity and some coexisting interferants were also evaluated. Under the optimum extraction conditions, an enrichment factor of 387 was obtained for a 100-mL sample solution. In combination with graphite furnace atomic absorption spectrometry, a very low detection limit (0.8 ng L - 1 ) and a relative standard deviation (2.5% at 50 ng L - 1 level) were achieved. Five seawater samples were analyzed by the proposed method without dilution, with detected Cd concentration in the range of 56.4-264.8 ng L - 1 and the relative spiked recoveries over 89%. For comparison, these samples were also analyzed by the Inductively Coupled Plasma Mass Spectrometry (ICP-MS) method after a 10-fold dilution for matrix effect elimination. Statistical analysis with a one-way ANOVA shows no significant differences (at 0.05 level) between the results obtained by the proposed and ICP-MS methods. Additionally, analysis of certified reference materials (GBW (E) 080040) shows good agreement with the certified value. These results indicate that this present method is very sensitive and reliable, and can effectively eliminate complex matrix interferences in seawater samples.

  14. Piezoelectric-tuned microwave cavity for absorption spectrometry

    DOEpatents

    Leskovar, Branko; Buscher, Harold T.; Kolbe, William F.

    1978-01-01

    Gas samples are analyzed for pollutants in a microwave cavity that is provided with two highly polished walls. One wall of the cavity is mechanically driven with a piezoelectric transducer at a low frequency to tune the cavity over a band of microwave frequencies in synchronism with frequency modulated microwave energy applied to the cavity. Absorption of microwave energy over the tuned frequencies is detected, and energy absorption at a particular microwave frequency is an indication of a particular pollutant in the gas sample.

  15. On-line ion-exchange preconcentration and determination of traces of platinum by electrothermal atomic absorption spectrometry.

    PubMed

    González García, M M; Sánchez Rojas, F; Bosch Ojeda, C; García de Torres, A; Cano Pavón, J M

    2003-04-01

    A method to determine trace amounts of platinum in different samples based on electrothermal atomic absorption spectrometry is described. The preconcentration step is performed on a chelating resin microcolumn [1,5-bis(2-pyridyl)-3-sulfophenyl methylene thiocarbonohydrazide (PSTH) immobilized on an anion-exchange resin (Dowex 1x8-200)] placed in the autosampler arm. The combination of a peristaltic pump for sample loading and the atomic absorption spectrometer pumps for elution through a selection valve simplifies the hardware. The peristaltic pump and the selection valve are easily controlled electronically with two switches placed in the autosampler, which are activated when the autosampler arm is down. Thus, the process is fully automated without any modification of the software of the atomic absorption spectrometer. Under the optimum conditions with a 60-s preconcentration time, a sample flow rate of 2.4 mL min(-1), and an injection volume of eluent of 40 microL, a linear calibration graph was obtained in the range 0-100 ng mL(-1). The enrichment factor was 14. The detection limit under these conditions is 1 ng mL(-1), and the relative standard deviation (RSD) is 1.6% for 10 ng mL(-1) of Pt. The method has been applied to the determination of platinum in catalyst, vegetation, soil, and natural water samples. The results showed good agreement with the certified value and the recoveries of Pt added to samples were 98-105%.

  16. Determination of Aluminum in Dialysis Concentrates by Atomic Absorption Spectrometry after Coprecipitation with Lanthanum Phosphate.

    PubMed

    Selvi, Emine Kılıçkaya; Şahin, Uğur; Şahan, Serkan

    2017-01-01

    This method was developed for the determination of trace amounts of aluminum(III) in dialysis concentrates using atomic absorption spectrometry after coprecipitation with lanthanum phosphate. The analytical parameters that influenced the quantitative coprecipitation of analyte including amount of lanthanum, amount of phosfate, pH and duration time were optimized. The % recoveries of the analyte ion were in the range of 95-105 % with limit of detection (3s) of 0.5 µg l -1 . Preconcentration factor was found as 1000 and Relative Standard Deviation (RSD) % value obtained from model solutions was 2.5% for 0.02 mg L -1 . The accuracy of the method was evaluated with standard reference material (CWW-TMD Waste Water). The method was also applied to most concentrated acidic and basic dialysis concentrates with satisfactory results.

  17. Reduction of interferences in graphite furnace atomic absorption spectrometry by multiple linear regression modelling

    NASA Astrophysics Data System (ADS)

    Grotti, Marco; Abelmoschi, Maria Luisa; Soggia, Francesco; Tiberiade, Christian; Frache, Roberto

    2000-12-01

    The multivariate effects of Na, K, Mg and Ca as nitrates on the electrothermal atomisation of manganese, cadmium and iron were studied by multiple linear regression modelling. Since the models proved to efficiently predict the effects of the considered matrix elements in a wide range of concentrations, they were applied to correct the interferences occurring in the determination of trace elements in seawater after pre-concentration of the analytes. In order to obtain a statistically significant number of samples, a large volume of the certified seawater reference materials CASS-3 and NASS-3 was treated with Chelex-100 resin; then, the chelating resin was separated from the solution, divided into several sub-samples, each of them was eluted with nitric acid and analysed by electrothermal atomic absorption spectrometry (for trace element determinations) and inductively coupled plasma optical emission spectrometry (for matrix element determinations). To minimise any other systematic error besides that due to matrix effects, accuracy of the pre-concentration step and contamination levels of the procedure were checked by inductively coupled plasma mass spectrometric measurements. Analytical results obtained by applying the multiple linear regression models were compared with those obtained with other calibration methods, such as external calibration using acid-based standards, external calibration using matrix-matched standards and the analyte addition technique. Empirical models proved to efficiently reduce interferences occurring in the analysis of real samples, allowing an improvement of accuracy better than for other calibration methods.

  18. Optimization of electrothermal atomization parameters for simultaneous multielement atomic absorption spectrometry

    USGS Publications Warehouse

    Harnly, J.M.; Kane, J.S.

    1984-01-01

    The effect of the acid matrix, the measurement mode (height or area), the atomizer surface (unpyrolyzed and pyrolyzed graphite), the atomization mode (from the wall or from a platform), and the atomization temperature on the simultaneous electrothermal atomization of Co, Cr, Cu, Fe, Mn, Mo, Ni, V, and Zn was examined. The 5% HNO3 matrix gave rise to severe irreproducibility using a pyrolyzed tube unless the tube was properly "prepared". The 5% HCl matrix did not exhibit this problem, and no problems were observed with either matrix using an unpyrolized tube or a pyrolyzed platform. The 5% HCl matrix gave better sensitivities with a pyrolyzed tube but the two matrices were comparable for atomization from a platform. If Mo and V are to be analyzed with the other seven elements, a high atomization temperature (2700??C or greater) is necessary regardless of the matrix, the measurement mode, the atomization mode, or the atomizer surface. Simultaneous detection limits (peak height with pyrolyzed tube atomization) were comparable to those of conventional atomic absorption spectrometry using electrothermal atomization above 280 nm. Accuracies and precisions of ??10-15% were found in the 10 to 120 ng mL-1 range for the analysis of NBS acidified water standards.

  19. Determination of total mercury in environmental and biological samples by flow injection cold vapour atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Murphy, James; Jones, Phil; Hill, Steve J.

    1996-12-01

    A simple and accurate method has been developed for the determination of total mercury in environmental and biological samples. The method utilises an off-line microwave digestion stage followed by analysis using a flow injection system with detection by cold vapour atomic absorption spectrometry. The method has been validated using two certified reference materials (DORM-1 dogfish and MESS-2 estuarine sediment) and the results agreed well with the certified values. A detection limit of 0.2 ng g -1 Hg was obtained and no significant interference was observed. The method was finally applied to the determination of mercury in river sediments and canned tuna fish, and gave results in the range 0.1-3.0 mg kg -1.

  20. Use of electrothermal atomic absorption spectrometry for size profiling of gold and silver nanoparticles.

    PubMed

    Panyabut, Teerawat; Sirirat, Natnicha; Siripinyanond, Atitaya

    2018-02-13

    Electrothermal atomic absorption spectrometry (ETAAS) was applied to investigate the atomization behaviors of gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) in order to relate with particle size information. At various atomization temperatures from 1400 °C to 2200 °C, the time-dependent atomic absorption peak profiles of AuNPs and AgNPs with varying sizes from 5 nm to 100 nm were examined. With increasing particle size, the maximum absorbance was observed at the longer time. The time at maximum absorbance was found to linearly increase with increasing particle size, suggesting that ETAAS can be applied to provide the size information of nanoparticles. With the atomization temperature of 1600 °C, the mixtures of nanoparticles containing two particle sizes, i.e., 5 nm tannic stabilized AuNPs with 60, 80, 100 nm citrate stabilized AuNPs, were investigated and bimodal peaks were observed. The particle size dependent atomization behaviors of nanoparticles show potential application of ETAAS for providing size information of nanoparticles. The calibration plot between the time at maximum absorbance and the particle size was applied to estimate the particle size of in-house synthesized AuNPs and AgNPs and the results obtained were in good agreement with those from flow field-flow fractionation (FlFFF) and transmission electron microscopy (TEM) techniques. Furthermore, the linear relationship between the activation energy and the particle size was observed. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Pigment identification in artwork using graphite furnace atomic absorption spectrometry.

    PubMed

    Goltz, D M; Coombs, J; Marion, C; Cloutis, E; Gibson, J; Attas, M; Choo-Smith, L-P; Collins, C

    2004-06-17

    The use of a sampling technique is described for the identification of metals from inorganic pigments in paint. The sampling technique involves gently contacting a cotton swab with the painted surface to physically remove a minute quantity ( approximately 1-2mug) of pigment. The amount of material removed from the painted surface is invisible to the unaided eye and does not cause any visible effect to the painted surface. The cotton swab was then placed in a 1.5ml polystyrene beaker containing HNO(3) to extract pigment metals prior to analysis using graphite furnace atomic absorption spectrometry (GFAAS). GFAAS is well suited for identifying pigment metals since it requires small samples and many pigments consist of main group elements (e.g. Al) as well as transition metals (e.g. Zn, Fe and Cd). Using Cd (cadmium red) as the test element, the reproducibility of sampling a paint surface with the cotton swab was approximately 13% in either a water or oil medium. To test the feasibility of cotton sampling for pigment identification, samples were obtained from paintings (watercolour and oil) of a local collection. Raman spectra provided complementary information to the GFAAS, which together are essential for positive identification of some pigments. For example, GFAAS indicated the presence of Cu, but the Raman spectra positively identified the modern copper pigment phthalocyanine green (Cu(C(32)Cl(16)N(8)). Both Raman spectroscopy and GFAAS were useful for identifying ZnO as a white pigment.

  2. Pre-analytic evaluation of volumetric absorptive microsampling and integration in a mass spectrometry-based metabolomics workflow.

    PubMed

    Volani, Chiara; Caprioli, Giulia; Calderisi, Giovanni; Sigurdsson, Baldur B; Rainer, Johannes; Gentilini, Ivo; Hicks, Andrew A; Pramstaller, Peter P; Weiss, Guenter; Smarason, Sigurdur V; Paglia, Giuseppe

    2017-10-01

    Volumetric absorptive microsampling (VAMS) is a novel approach that allows single-drop (10 μL) blood collection. Integration of VAMS with mass spectrometry (MS)-based untargeted metabolomics is an attractive solution for both human and animal studies. However, to boost the use of VAMS in metabolomics, key pre-analytical questions need to be addressed. Therefore, in this work, we integrated VAMS in a MS-based untargeted metabolomics workflow and investigated pre-analytical strategies such as sample extraction procedures and metabolome stability at different storage conditions. We first evaluated the best extraction procedure for the polar metabolome and found that the highest number and amount of metabolites were recovered upon extraction with acetonitrile/water (70:30). In contrast, basic conditions (pH 9) resulted in divergent metabolite profiles mainly resulting from the extraction of intracellular metabolites originating from red blood cells. In addition, the prolonged storage of blood samples at room temperature caused significant changes in metabolome composition, but once the VAMS devices were stored at - 80 °C, the metabolome remained stable for up to 6 months. The time used for drying the sample did also affect the metabolome. In fact, some metabolites were rapidly degraded or accumulated in the sample during the first 48 h at room temperature, indicating that a longer drying step will significantly change the concentration in the sample. Graphical abstract Volumetric absorptive microsampling (VAMS) is a novel technology that allows single-drop blood collection and, in combination with mass spectrometry (MS)-based untargeted metabolomics, represents an attractive solution for both human and animal studies. In this work, we integrated VAMS in a MS-based untargeted metabolomics workflow and investigated pre-analytical strategies such as sample extraction procedures and metabolome stability at different storage conditions. The latter revealed that

  3. Rapid separation on copper powder of total mercury in blood and determination of mercury by flameless atomic absorption spectrometry.

    PubMed

    Dogan, S; Haerdi, W

    1979-01-01

    The determination of mercury in blood by flameless atomic absorption spectrometry (FAAS) has been described. Prior to its analysis, the sample was decomposed by combustion and separated on a copper powder micro-column. A special type of cell has been used which gives a better sensitivity compared with the types of cells described in the literature and the method of FAAS analysis has been improved. The sensitivity of 0.1 ng for 1% absorbance was observed and the standard deviation for six determinations at this level was found to be +/- 0.05 ng, for 95% probability.

  4. Simple method for determination of selenium in biological materials by flameless atomic-absorption spectrometry using a carbon-tube atomizer.

    PubMed

    Ishizaki, M

    1978-03-01

    A method for determination of selenium in biological materials by flameless atomic-absorption spectrometry using a carbon-tube atomizer is described. The sample is burned by an oxygen-flask combustion procedure, the resulting solution is treated with a cation-exchange resin to eliminate interfering cations, the selenium is extracted with dithizone in carbon tetrachloride and the resulting selenium dithizonate is combined with nickel nitrate in the carbon tube to enhance the sensitivity for selenium and avoid volatilization losses. The method measures selenium concentrations as low as 0.01 mug/g with a relative standard deviation of 8%.

  5. Multicomutation flow system for manganese speciation by solid phase extraction and flame atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Tobiasz, Anna; Sołtys, Monika; Kurys, Ewa; Domagała, Karolina; Dudek-Adamska, Danuta; Walas, Stanisław

    2017-08-01

    In the paper an application of solid phase extraction technique for speciation analysis of manganese in water samples with the use of flame atomic absorption spectrometry is presented. Two types of sorbents, activated silica gel and Dowex 1 × 4, were used respectively for simultaneously Mn2 + and MnO42 - retention and preconcentration. The whole procedure was realized in multicomutation flow system. Different conditions like: type and concentration of eluent, sample pH and loading time were tested during the study. Under appropriate conditions, it was possible to obtained enrichment factors of 20 and 16 for Mn(II) and Mn(VII), respectively. Precision of the procedure was close to 4% (measured as relative standard deviation), whereas the detection limit (3σ) was 1.4 μg·L- 1 for Mn(II) and 4.8 μg·L- 1 for Mn(VII).

  6. Determination of sulfur in food by high resolution continuum source flame molecular absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Zambrzycka, Elżbieta; Godlewska-Żyłkiewicz, Beata

    2014-11-01

    In the present work, a fast, simple and sensitive analytical method for determination of sulfur in food and beverages by high resolution continuum source flame molecular absorption spectrometry was developed. The determination was performed via molecular absorption of carbon monosulfide, CS. Different CS rotational lines (257.959 nm, 258.033 nm, 258.055 nm), number of pixels and types of standard solution of sulfur, namely: sulfuric acid, sodium sulfate, ammonium sulfate, sodium sulfite, sodium sulfide, DL-cysteine, and L-cystine, were studied in terms of sensitivity, repeatability of results as well as limit of detection and limit of quantification. The best results were obtained for measurements of absorption of the CS molecule at 258.055 nm at the wavelength range covering 3 pixels and DL-cysteine in 0.2 mol L- 1 HNO3 solution as a calibration standard. Under optimized conditions the limit of detection and the limit of quantification achieved for sulfur were 10.9 mg L- 1 and 36.4 mg L- 1, respectively. The repeatability of the results expressed as relative standard deviation was typically < 5%. The accuracy of the method was tested by analysis of digested biological certified reference materials (soya bean flour, corn flour and herbs) and recovery experiment for beverage samples with added known amount of sulfur standard. The recovery of analyte from such samples was in the range of 93-105% with the repeatability in the range of 4.1-5.0%. The developed method was applied for the determination of sulfur in milk (194 ± 10 mg kg- 1), egg white (2188 ± 29 mg kg- 1), mineral water (31.0 ± 0.9 mg L- 1), white wine (260 ± 4 mg L- 1) and red wine (82 ± 2 mg L- 1), as well as in sample rich in ions, such as bitter mineral water (6900 ± 100 mg L- 1).

  7. A method for the routine determination of aluminium in serum and water by flameless atomic absorption spectrometry.

    PubMed

    Parkinson, I S; Ward, M K; Kerr, D N

    1982-10-27

    A simple but reliable method for the routine determination of aluminium in serum and water by flameless atomic absorption spectrometry is described. No preparatory procedures are required for water samples, although serum is mixed with a wetting agent (Triton X-100) to allow complete combustion of the samples and to improve analytical precision. Precautions to prevent contamination during sample handling are discussed and instrumental parameters are defined. The method has a sensitivity of 35.5 pg and detection limits of 2.3 micrograms Al/l for serum and 1.3 micrograms Al/l for water. The method was used to determine the aluminium concentration in serum of 46 normal subjects. The mean aluminium content was 7.3 micrograms/l (range 2--15 micrograms/l.

  8. Cu determination in crude oil distillation products by atomic absorption and inductively coupled plasma mass spectrometry after analyte transfer to aqueous solution

    NASA Astrophysics Data System (ADS)

    Kowalewska, Zofia; Ruszczyńska, Anna; Bulska, Ewa

    2005-03-01

    Cu was determined in a wide range of petroleum products from crude oil distillation using flame atomic absorption spectrometry (FAAS), electrothermal atomic absorption spectrometry (ETAAS) and inductively coupled plasma mass spectrometry (ICP-MS). Different procedures of sample preparation were evaluated: (i) mineralization with sulfuric acid in an open system, (ii) mineralization in a closed microwave system, (iii) combustion in hydrogen-oxygen flame in the Wickbold's apparatus, (iv) matrix evaporation followed by acid dissolution, and (v) acidic extraction. All the above procedures led to the transfer of the analyte into an aqueous solution for the analytical measurement step. It was found that application of FAAS was limited to the analysis of the heaviest petroleum products of high Cu content. In ICP-MS, the use of internal reference method (with Rh or In as internal reference element) was required to eliminate the matrix effects in the analysis of extracts and the concentrated solutions of mineralized heavy petroleum products. The detection limits (in original samples) were equal to, respectively, 10, 86, 3.3, 0.9 and 0.4 ng g - 1 in procedures i-v with ETAAS detection and 10, 78, 1.1 and 0.5 ng g - 1 in procedures i-iii and v with ICP-MS detection. The procedures recommended here were validated by recovery experiments, certified reference materials analysis and comparison of results, obtained for a given sample, in different ways. The Cu content in the analyzed samples was: 50-110 ng g - 1 in crude oil, < 0.4-6 ng g - 1 in gasoline, < 0.5-2 ng g - 1 in atmospheric oil, < 6-100 ng g - 1 in heavy vacuum oil and 140-300 ng g - 1 in distillation residue.

  9. Application of Plackett-Burman and Doehlert designs for optimization of selenium analysis in plasma with electrothermal atomic absorption spectrometry.

    PubMed

    El Ati-Hellal, Myriam; Hellal, Fayçal; Hedhili, Abderrazek

    2014-10-01

    The aim of this study was the optimization of selenium determination in plasma samples with electrothermal atomic absorption spectrometry using experimental design methodology. 11 variables being able to influence selenium analysis in human blood plasma by electrothermal atomic absorption spectrometry (ETAAS) were evaluated with Plackett-Burman experimental design. These factors were selected from sample preparation, furnace program and chemical modification steps. Both absorbance and background signals were chosen as responses in the screening approach. Doehlert design was used for method optimization. Results showed that only ashing temperature has a statistically significant effect on the selected responses. Optimization with Doehlert design allowed the development of a reliable method for selenium analysis with ETAAS. Samples were diluted 1/10 with 0.05% (v/v) TritonX-100+2.5% (v/v) HNO3 solution. Optimized ashing and atomization temperatures for nickel modifier were 1070°C and 2270°C, respectively. A detection limit of 2.1μgL(-1) Se was obtained. Accuracy of the method was checked by the analysis of selenium in Seronorm™ Trace element quality control serum level 1. The developed procedure was applied for the analysis of total selenium in fifteen plasma samples with standard addition method. Concentrations ranged between 24.4 and 64.6μgL(-1), with a mean of 42.6±4.9μgL(-1). The use of experimental designs allowed the development of a cheap and accurate method for selenium analysis in plasma that could be applied routinely in clinical laboratories. Copyright © 2014 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

  10. Determination of mercury distribution inside spent compact fluorescent lamps by atomic absorption spectrometry.

    PubMed

    Rey-Raap, Natalia; Gallardo, Antonio

    2012-05-01

    In this study, spent compact fluorescent lamps were characterized to determine the distribution of mercury. The procedure used in this research allowed mercury to be extracted in the vapor phase, from the phosphor powder, and the glass matrix. Mercury concentration in the three phases was determined by the method known as cold vapor atomic absorption spectrometry. Median values obtained in the study showed that a compact fluorescent lamp contained 24.52±0.4ppb of mercury in the vapor phase, 204.16±8.9ppb of mercury in the phosphor powder, and 18.74±0.5ppb of mercury in the glass matrix. There are differences in mercury concentration between the lamps since the year of manufacture or the hours of operation affect both mercury content and its distribution. The 85.76% of the mercury introduced into a compact fluorescent lamp becomes a component of the phosphor powder, while more than 13.66% is diffused through the glass matrix. By washing and eliminating all phosphor powder attached to the glass surface it is possible to classified the glass as a non-hazardous waste. Copyright © 2011 Elsevier Ltd. All rights reserved.

  11. Acid effects on the measurement of mercury by cold vapor atomic absorption spectrometry

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Adeloju, S.B.; Mann, T.F.

    1987-07-01

    The influence of nitric, hydrochloric and sulfuric acids on the measurement of mercury by cold vapor atomic absorption spectrometry has been investigated. Small pre-reduction peaks associated with the instability of mercury were observed in solutions containing less than or equal to 12.5, < 2 and less than or equal to 12.5% v/v of each acid, respectively. Mercury was found to be most stable in greater than or equal to 2% v/v hydrochloric acid and the measured absorbance was not greatly influenced by varying concentration of the acid. The mercury absorbance measurements were more sensitive in solutions containing less than ormore » equal to 6.3% v/v hydrochloric acid than in similar concentrations of nitric and sulfuric acids. The use of the three acids as a digestion mixture result in serious interference from nitrogen oxides. The interference was removed by use of expelling agents such as urea and sulfamic acid or overcome by use of excess stannous chloride, prior to the reduction of mercury(II) ions. The determination of mercury in NBS albacore tuna using both of these approaches to overcome the interference problem proved to be successful.« less

  12. Determination of trace elements in automotive fuels by filter furnace atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Anselmi, Anna; Tittarelli, Paolo; Katskov, Dmitri A.

    2002-03-01

    The determination of Cd, Cr, Cu, Pb and Ni was performed in gasoline and diesel fuel samples by electrothermal atomic absorption spectrometry using the Transverse Heated Filter Atomizer (THFA). Thermal conditions were experimentally defined for the investigated elements. The elements were analyzed without addition of chemical modifiers, using organometallic standards for the calibration. Forty-microliter samples were injected into the THFA. Gasoline samples were analyzed directly, while diesel fuel samples were diluted 1:4 with n-heptane. The following characteristic masses were obtained: 0.8 pg Cd, 6.4 pg Cr, 12 pg Cu, 17 pg Pb and 27 pg Ni. The limits of determination for gasoline samples were 0.13 μg/kg Cd, 0.4 μg/kg Cr, 0.9 μg/kg Cu, 1.5 μg/kg Pb and 2.5 μg/kg Ni. The corresponding limit of determination for diesel fuel samples was approximately four times higher for all elements. The element recovery was performed using the addition of organometallic compounds to gasoline and diesel fuel samples and was between 85 and 105% for all elements investigated.

  13. Crashworthiness of Aluminium Tubes; Part 2: Improvement of Hydroforming Operation to Increase Absorption Energy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    D'Amours, Guillaume; Rahem, Ahmed; Mayer, Robert

    2007-05-17

    The motivation to reduce overall vehicle weight within the automotive sector drives the substitution of lightweight materials such as aluminium alloys for structural components. Such a substitution requires a significant amount of development to manufacture structurally parts such that the energy absorption characteristics are not sacrificed in the event of crash. The effects of the manufacturing processes on the crash performance of automotive structural components must be better understood to ensure improved crashworthiness. This paper presents results of an experimental and numerical investigation of the crash response and energy absorption properties of impacted hydroformed aluminium alloy tubes. Crash experiments onmore » hydroformed tubes were performed using a deceleration sled test at the General Motors Technical Center. Results from axial crush testing showed that an important parameter that influences the energy absorption characteristics during crash was the thickness reduction caused by circumferential expansion of the tube during hydroforming. It was found that that the energy absorption decreased as the corner radius decreased, which results because of increased thinning. Sensitivity studies of end feeding parameters, such as end feed level and profile, were carried out to evaluate their impact on the energy absorption of the aluminium tubes.« less

  14. Crashworthiness of Aluminium Tubes; Part 2: Improvement of Hydroforming Operation to Increase Absorption Energy

    NASA Astrophysics Data System (ADS)

    D'Amours, Guillaume; Rahem, Ahmed; Mayer, Robert; Williams, Bruce; Worswick, Michael

    2007-05-01

    The motivation to reduce overall vehicle weight within the automotive sector drives the substitution of lightweight materials such as aluminium alloys for structural components. Such a substitution requires a significant amount of development to manufacture structurally parts such that the energy absorption characteristics are not sacrificed in the event of crash. The effects of the manufacturing processes on the crash performance of automotive structural components must be better understood to ensure improved crashworthiness. This paper presents results of an experimental and numerical investigation of the crash response and energy absorption properties of impacted hydroformed aluminium alloy tubes. Crash experiments on hydroformed tubes were performed using a deceleration sled test at the General Motors Technical Center. Results from axial crush testing showed that an important parameter that influences the energy absorption characteristics during crash was the thickness reduction caused by circumferential expansion of the tube during hydroforming. It was found that that the energy absorption decreased as the corner radius decreased, which results because of increased thinning. Sensitivity studies of end feeding parameters, such as end feed level and profile, were carried out to evaluate their impact on the energy absorption of the aluminium tubes.

  15. On-line ionic liquid-based preconcentration system coupled to flame atomic absorption spectrometry for trace cadmium determination in plastic food packaging materials.

    PubMed

    Martinis, Estefanía M; Olsina, Roberto A; Altamirano, Jorgelina C; Wuilloud, Rodolfo G

    2009-05-15

    A novel on-line preconcentration method based on liquid-liquid (L-L) extraction with room temperature ionic liquids (RTILs) coupled to flame atomic absorption spectrometry (FAAS) was developed for cadmium determination in plastic food packaging materials. The methodology is based on the complexation of Cd with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) reagent after sample digestion followed by extraction of the complex with the RTIL 1-butyl-3-methylimidazolium hexafluorophosphate ([C(4)mim][PF(6)]). The mixture was loaded into a flow injection analysis (FIA) manifold and the RTIL rich-phase was retained in a microcolumn filled with silica gel. The RTIL rich-phase was then eluted directly into FAAS. A enhancement factor of 35 was achieved with 20 mL of sample. The limit of detection (LOD), obtained as IUPAC recommendation, was 6 ng g(-1) and the relative standard deviation (R.S.D.) for 10 replicates at 10 microg L(-1) Cd concentration level was 3.9%, calculated at the peak heights. The calibration graph was linear and a correlation coefficient of 0.9998 was achieved. The accuracy of the method was evaluated by both a recovery study and comparison of results with direct determination by electrothermal atomic absorption spectrometry (ETAAS). The method was successfully applied for Cd determination in plastic food packaging materials and Cd concentrations found were in the range of 0.04-10.4 microg g(-1).

  16. Direct sampling graphite furnace atomic absorption spectrometry - feasibility of Na and K determination in desalted crude oil

    NASA Astrophysics Data System (ADS)

    Seeger, Tassia S.; Machado, Eduarda Q.; Flores, Erico M. M.; Mello, Paola A.; Duarte, Fabio A.

    2018-03-01

    In this study, Na and K were determined in desalted crude oil by direct sampling graphite furnace atomic absorption spectrometry (DS-GF AAS), with the use of a Zeeman-effect background correction system with variable magnetic field. The analysis was performed in low and high sensitivity conditions. Sodium determination was performed in two low-sensitivity conditions: 1) main absorption line (589.0 nm), gas stop flow during the atomization step and 3-field dynamic mode (0.6-0.8 T); and 2) secondary absorption line (330.3 nm), gas stop flow during the atomization and 2-field mode (0.8 T). In K determination, some parameters, such as high-sensitivity mode, main absorption line (766.5 nm), gas stop flow during the atomization and 2-field mode (0.8 T), were used. Suitability of chemical modifiers, such as Pd and W-Ir was also evaluated. The heating program for Na and K was based on the pyrolysis and atomization curves. Calibration was performed by aqueous standards. Accuracy was evaluated by the analysis of Green Petroleum Coke (SRM NIST 2718) and Trace Elements in Fuel Oil (SRM NIST 1634c). Recovery tests were also performed and results were compared with those obtained by GF AAS after crude oil digestion by microwave-assisted digestion. The characteristic mass of Na was 17.1 pg and 0.46 ng in conditions 1 and 2, respectively, while the one of K was 1.4 pg. Limits of detection and quantification by DS-GF AAS were 30 and 40 ng g-1 for Na and 3.2 and 4.2 ng g-1 for K, respectively. Sodium and K were determined in three crude oil samples with API density ranging from 20.9 to 28.0. Sodium and K concentration ranged from 1.5 to 73 μg g-1 and from 23 to 522 ng g-1, respectively.

  17. Determination of sulfur in bovine serum albumin and L-cysteine using high-resolution continuum source molecular absorption spectrometry of the CS molecule

    NASA Astrophysics Data System (ADS)

    Andrade-Carpente, Eva; Peña-Vázquez, Elena; Bermejo-Barrera, Pilar

    2016-08-01

    In this study, the content of sulfur in bovine serum albumin and L-cysteine was determined using high-resolution continuum source molecular absorption spectrometry of the CS molecule, generated in a reducing air-acetylene flame. Flame conditions (height above the burner, measurement time) were optimized using a 3.0% (v/v) sulfuric acid solution. A microwave lab station (Ethos Plus MW) was used for the digestion of both compounds. During the digestion step, sulfur was converted to sulfate previous to the determination. Good repeatability (4-10%) and analytical recovery (91-106%) was obtained.

  18. Determination of mercury in fish tissue using a minianalyzer based on cold vapor atomic absorption spectrometry at the 184.9 nm line.

    PubMed

    Rizea, Maria-Cristina; Bratu, Maria-Cristina; Danet, Andrei Florin; Bratu, Adrian

    2007-09-01

    A sensitive method was proposed and optimized for the determination of total mercury in fish tissue by using wet digestion, followed by cold vapor atomic absorption spectrometry (CVAAS) at the main resonance line of mercury (184.9 nm). The measurements were made using a new type of a non-dispersive mercury minianalyzer. This instrument was initially designed and built for atmospheric mercury-vapor detection. For determining mercury in aqueous samples, the minianalyzer was linked with a mercury/hydride system, Perkin Elmer Model MHS-10. To check the method, the analyzed samples were spiked with a standard solution of mercury. The recoveries of mercury spiked to wet fish tissue were >90% for 0.5 - 0.8 g samples. The results showed a better sensitivity (about 2.5 times higher) when using the mercury absorption line at 184.9 nm compared with the sensitivity obtained by conventional CVAAS at 253.7 nm.

  19. Micro-sampling method based on high-resolution continuum source graphite furnace atomic absorption spectrometry for calcium determination in blood and mitochondrial suspensions.

    PubMed

    Gómez-Nieto, Beatriz; Gismera, Mª Jesús; Sevilla, Mª Teresa; Satrústegui, Jorgina; Procopio, Jesús R

    2017-08-01

    A micro-sampling and straightforward method based on high resolution continuum source atomic absorption spectrometry (HR-CS AAS) was developed to determine extracellular and intracellular Ca in samples of interest in clinical and biomedical analysis. Solid sampling platforms were used to introduce the micro-samples into the graphite furnace atomizer. The secondary absorption line for Ca, located at 239.856nm, was selected to carry out the measurements. Experimental parameters such as pyrolysis and atomization temperatures and the amount of sample introduced for the measurements were optimized. Calibration was performed using aqueous standards and the approach to measure at the wings of the absorption lines was employed for the expansion of the linear response range. The limit of detection was of 0.02mgL -1 Ca (0.39ng Ca) and the upper limit of linear range was increased up to 8.0mgL -1 Ca (160ng Ca). The proposed method was used to determine Ca in mitochondrial suspensions and whole blood samples with successful results. Adequate recoveries (within 91-107%) were obtained in the tests performed for validation purposes. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Solid sampling determination of total fluorine in baby food samples by high-resolution continuum source graphite furnace molecular absorption spectrometry.

    PubMed

    Ozbek, Nil; Akman, Suleyman

    2016-11-15

    This study describes the applicability of solid sampling technique for the determination of fluorine in various baby foods via molecular absorption of calcium monofluoride generated in a graphite furnace of high-resolution continuum source atomic absorption spectrometry. Fluorine was determined at CaF wavelength, 606.440nm in a graphite tube applying a pyrolysis temperature of 1000°C and a molecule forming temperature of 2200°C. The limit of detection and characteristic mass of the method were 0.20ng and 0.17ng of fluorine, respectively. The fluorine concentrations determined in standard reference sample (bush branches and leaves) were in good agreement with the certified values. By applying the optimized parameters, the concentration of fluorine in various baby foods were determined. The fluorine concentrations were ranged from

  1. Determination of mercury in an assortment of dietary supplements using an inexpensive combustion atomic absorption spectrometry technique.

    PubMed

    Levine, Keith E; Levine, Michael A; Weber, Frank X; Hu, Ye; Perlmutter, Jason; Grohse, Peter M

    2005-01-01

    The concentrations of mercury in forty, commercially available dietary supplements, were determined using a new, inexpensive analysis technique. The method involves thermal decomposition, amalgamation, and detection of mercury by atomic absorption spectrometry with an analysis time of approximately six minutes per sample. The primary cost savings from this approach is that labor-intensive sample digestion is not required prior to analysis, further automating the analytical procedure. As a result, manufacturers and regulatory agencies concerned with monitoring lot-to-lot product quality may find this approach an attractive alternative to the more classical acid-decomposition, cold vapor atomic absorption methodology. Dietary supplement samples analyzed included astragalus, calcium, chromium picolinate, echinacea, ephedra, fish oil, ginger, ginkgo biloba, ginseng, goldenseal, guggul, senna, St John's wort, and yohimbe products. Quality control samples analyzed with the dietary supplements indicated a high level of method accuracy and precision. Ten replicate preparations of a standard reference material (NIST 1573a, tomato leaves) were analyzed, and the average mercury recovery was 109% (2.0% RSD). The method quantitation limit was 0.3 ng, which corresponded to 1.5 ng/g sample. The highest found mercury concentration (123 ng/g) was measured in a concentrated salmon oil sample. When taken as directed by an adult, this product would result in an approximate mercury ingestion of 7 mug per week.

  2. Determination of gold and cobalt dopants in advanced materials based on tin oxide by slurry sampling high-resolution continuum source graphite furnace atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Filatova, Daria G.; Eskina, Vasilina V.; Baranovskaya, Vasilisa B.; Vladimirova, Svetlana A.; Gaskov, Alexander M.; Rumyantseva, Marina N.; Karpov, Yuri A.

    2018-02-01

    A novel approach is developed for the determination of Co and Au dopants in advanced materials based on tin oxide using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR CS GFAAS) with direct slurry sampling. Sodium carboxylmethylcellulose (Na-CMC) is an effective stabilizer for diluted suspensions. Use Na-CMC allows to transfer the analytes into graphite furnace completely and reproducibly. The relative standard deviation obtained by HR CS GFAAS was not higher than 4%. Accuracy was proven by means inductively coupled plasma mass spectrometry (ICP-MS) in solutions after decomposition as a comparative technique. To determine Au and Co in the volume of SnO2, the acid decomposition conditions (HCl, HF) of the samples were suggested by means of an autoclave in a microwave oven.

  3. Determination of mercury by multisyringe flow injection system with cold-vapor atomic absorption spectrometry.

    PubMed

    Leal, L O; Elsholz, O; Forteza, R; Cerdà, V

    2006-07-28

    A new software-controlled time-based multisyringe flow injection system for mercury determination by cold-vapor atomic absorption spectrometry is proposed. Precise known volumes of sample, reducing agent (1.1% SnCl2 in 3% HCl) and carrier (3% HCl) are dispensed into a gas-liquid separation cell with a multisyringe burette coupled with one three-way solenoid valve. An argon flow delivers the reduced mercury to the spectrometer. The optimization of the system was carried out testing reaction coils and gas-liquid separators of different design as well as changing parameters, such as sample and reagents volumes, reagent concentrations and carrier gas flow rate, among others. The analytical curves were obtained within the range 50-5000 ng L(-1). The detection limit (3sigma(b)/S) achieved is 5 ng L(-1). The relative standard deviation (R.S.D.) was 1.4%, evaluated from 16 successive injections of 250 ng L(-1) Hg standard solution. The injection and sample throughput per hour were 44 and 11, respectively. This technique was validated by means of solid and water reference materials with good agreement with the certified values and was successfully applied to fish samples.

  4. Investigation of an alternating current plasma as an element selective atomic emission detector for high-resolution capillary gas chromatography and as a source for atomic absorption and atomic emission spectrometry

    NASA Astrophysics Data System (ADS)

    Ombaba, Jackson M.

    This thesis deals with the construction and evaluation of an alternating current plasma (ACP) as an element-selective detector for high resolution capillary gas chromatography (GC) and as an excitation source for atomic absorption spectrometry (AAS) and atomic emission spectrometry (AES). The plasma, constrained in a quartz discharge tube at atmospheric pressure, is generated between two copper electrodes and utilizes helium as the plasma supporting gas. The alternating current plasma power source consists of a step-up transformer with a secondary output voltage of 14,000 V at a current of 23 mA. The device exhibits a stable signal because the plasma is self-seeding and reignites itself every half cycle. A tesla coil is not required to commence generation of the plasma if the ac voltage applied is greater than the breakdown voltage of the plasma-supporting gas. The chromatographic applications studied included the following: (1) the separation and selective detection of the organotin species, tributyltin chloride (TBT) and tetrabutyltin (TEBT), in environmental matrices including mussels (Mvutilus edullus) and sediment from Boston Harbor, industrial waste water and industrial sludge, and (2) the detection of methylcyclopentadienyl manganesetricarbonyl (MMT) and similar compounds used as gasoline additives. An ultrasonic nebulizer (common room humidifier) was utilized as a sample introduction device for aqueous solutions when the ACP was employed as an atomization source for atomic absorption spectrometry and as an excitation source for atomic emission spectrometry. Plasma diagnostic parameters studied include spatial electron number density across the discharge tube, electronic, excitation and ionization temperatures. Interference studies both in absorption and emission modes were also considered. Figures of merits of selected elements both in absorption and emission modes are reported. The evaluation of a computer-aided optimization program, Drylab GC, using

  5. Introduction of organic/hydro-organic matrices in inductively coupled plasma optical emission spectrometry and mass spectrometry: a tutorial review. Part II. Practical considerations.

    PubMed

    Leclercq, Amélie; Nonell, Anthony; Todolí Torró, José Luis; Bresson, Carole; Vio, Laurent; Vercouter, Thomas; Chartier, Frédéric

    2015-07-23

    Inductively coupled plasma optical emission spectrometry (ICP-OES) and mass spectrometry (ICP-MS) are increasingly used to carry out analyses in organic/hydro-organic matrices. The introduction of such matrices into ICP sources is particularly challenging and can be the cause of numerous drawbacks. This tutorial review, divided in two parts, explores the rich literature related to the introduction of organic/hydro-organic matrices in ICP sources. Part I provided theoretical considerations associated with the physico-chemical properties of such matrices, in an attempt to understand the induced phenomena. Part II of this tutorial review is dedicated to more practical considerations on instrumentation, instrumental and operating parameters, as well as analytical strategies for elemental quantification in such matrices. Two important issues are addressed in this part: the first concerns the instrumentation and optimization of instrumental and operating parameters, pointing out (i) the description, benefits and drawbacks of different kinds of nebulization and desolvation devices and the impact of more specific instrumental parameters such as the injector characteristics and the material used for the cone; and, (ii) the optimization of operating parameters, for both ICP-OES and ICP-MS. Even if it is at the margin of this tutorial review, Electrothermal Vaporization and Laser Ablation will also be shortly described. The second issue is devoted to the analytical strategies for elemental quantification in such matrices, with particular insight into the isotope dilution technique, particularly used in speciation analysis by ICP-coupled separation techniques. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. A critical review of inductively coupled plasma-mass spectrometry for geoanalysis, geochemistry and hydrology, Part 1. Analytical performance

    USGS Publications Warehouse

    Brenner, I.B.; Taylor, Howard E.

    1992-01-01

    Present-day inductively coupled plasma-mass spectrometry (ICP-MS) instrumentation is described briefly. Emphasis is placed on performance characteristics for geoanalysis, geochemistry, and hydrology. Applications where ICP-MS would be indispensable are indicated. Determination of geochemically diagnostic trace elements (such as the rare earth elements [REE], U and Th), of isotope ratios for fingerprinting, tracer and other geo-isotope applications, and benchmark isotope dilution determinations are considered to be typical priority applications for ICP-MS. It is concluded that ICP-MS furnishes unique geoanalytical and environmental data that are not readily provided by conventional spectroscopic (emission and absorption) techniques.

  7. [Determination of Al, Be, Cd, Co, Cr, Mn, Ni, Pb, Se and Tl in whole blood by atomic absorption spectrometry without preliminary sample digestion].

    PubMed

    Ivanenko, N B; Ivanenko, A A; Solov'ev, N D; Navolotskiĭ, D V; Pavlova, O V; Ganeev, A A

    2014-01-01

    Methods of whole blood trace element determination by Graphite furnace atomic absorption spectrometry (in the variant of Zeeman's modulation polarization spectrometry) have been proposed. They do not require preliminary sample digestion. Furnace programs, modifiers and blood dilution factors were optimized. Seronorm™ human whole blood reference materials were used for validation. Dynamic ranges (for undiluted blood samples) were: Al 8 ¸ 210 мg/L; Be 0.3 ¸ 50 мg/L; Cd 0.2 ¸ 75 мg/L; Сo 5 ¸ 350 мg/L; Cr 10 ¸ 100 мg/L; Mn 6 ¸ 250 мg/L; Ni 10 ¸ 350 мg/L; Pb 3 ¸ 240 мg/L; Se 10 ¸ 500 мg/L; Tl 2 ¸ 600 мg/L. Precision (RSD) for the middle of dynamic range ranged from 5% for Mn to 11 for Se.

  8. Matching the laser wavelength to the absorption properties of matrices increases the ion yield in UV-MALDI mass spectrometry.

    PubMed

    Wiegelmann, Marcel; Soltwisch, Jens; Jaskolla, Thorsten W; Dreisewerd, Klaus

    2013-09-01

    A high analytical sensitivity in ultraviolet matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) is only achieved if the laser wavelength corresponds to a high optical absorption of the matrix. Laser fluence and the physicochemical properties of the compounds, e.g., the proton affinity, also influence analytical sensitivity significantly. In combination, these parameters determine the amount of material ejected per laser pulse and the ion yield, i.e., the fraction of ionized biomolecules. Here, we recorded peptide ion signal intensities as a function of these parameters. Three cinnamic acid matrices were investigated: α-cyano-4-hydroxycinnamic acid, α-cyano-4-chlorocinnamic acid, and α-cyano-2,4-difluorocinnamic acid. In addition, 2,5-dihydroxybenzoic acid was used in comparison experiments. Ion signal intensities "per laser shot" and integrated ion signal intensities were acquired over 900 consecutive laser pulses applied on distinct positions on the dried-droplet sample preparations. With respect to laser wavelength, the two standard MALDI wavelengths of 337/355 nm were investigated. Also, 305 or 320 nm was selected to account for the blue-shifted absorption profiles of the halogenated derivatives. Maximal peptide ion intensities were obtained if the laser wavelength fell within the peak of the absorption profile of the compound and for fluences two to three times the corresponding ion detection threshold. The results indicate ways for improving the analytical sensitivity in MALDI-MS, and in particular for MALDI-MS imaging applications where a limited amount of material is available per irradiated pixel.

  9. Incorporating Biological Mass Spectrometry into Undergraduate Teaching Labs, Part 1: Identifying Proteins Based on Molecular Mass

    ERIC Educational Resources Information Center

    Arnquist, Isaac J.; Beussman, Douglas J.

    2007-01-01

    Biological mass spectrometry is an important analytical technique in drug discovery, proteomics, and research at the biology-chemistry interface. Currently, few hands-on opportunities exist for undergraduate students to learn about this technique. With the 2002 Nobel Prize being awarded, in part, for the development of biological mass…

  10. Quantification of absorption, retention and elimination of two different oral doses of vitamin A in Zambian boys using accelerator mass spectrometry

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Aklamati, E K; Mulenga, M; Dueker, S R

    A recent survey indicated that high-dose vitamin A supplements (HD-VAS) had no apparent effect on vitamin A (VA) status of Zambian children <5 y of age. To explore possible reasons for the lack of response to HD-VAS among Zambian children, we quantified the absorption, retention, and urinary elimination of either a single HDVAS (60 mg) or a smaller dose of stable isotope (SI)-labeled VA (5 mg), which was used to estimate VA pool size, in 3-4 y old Zambian boys (n = 4 for each VA dose). A 25 nCi tracer dose of [{sup 14}C{sub 2}]-labeled VA was co-administered withmore » the HD-VAS or SI-labeled VA, and 24-hr stool and urine samples were collected for 3 and 7 consecutive days, respectively, and 24-hr urine samples at 4 later time points. Accelerator Mass Spectrometry (AMS) was used to measure the cumulative excretion of {sup 14}C in stool and urine 3d after dosing to estimate, respectively, absorption and retention of the VAS and SI-labeled VA. The urinary elimination rate (UER) was estimated by plotting {sup 14}C in urine vs. time, and fitting an exponential equation to the data. Estimates of mean absorption, retention and the UER were 83.8 {+-} 7.1%, 76.3 {+-} 6.7%, and 1.9 {+-} 0.6%/d, respectively, for the HD-VAS and 76.5 {+-} 9.5%, 71.1 {+-} 9.4%, and 1.8 {+-} 1.2%/d, respectively for the smaller dose of SI-labeled VA. Estimates of absorption, retention and the UER did not differ by size of the VA dose administered (P=0.26, 0.40, 0.88, respectively). Estimated absorption and retention were negatively associated with reported fever (P=0.011) and malaria (P =0.010). HD-VAS and SI-labeled VA were adequately absorbed, retained and utilized in apparently healthy Zambian preschool-age boys, although absorption and retention may be affected by recent infections.« less

  11. Method of trivalent chromium concentration determination by atomic spectrometry

    DOEpatents

    Reheulishvili, Aleksandre N [Tbilisi, 0183, GE; Tsibakhashvili, Neli Ya [Tbilisi, 0101, GE

    2006-12-12

    A method is disclosed for determining the concentration of trivalent chromium Cr(III) in a sample. The addition of perchloric acid has been found to increase the atomic chromium spectrometric signal due to Cr(III), while leaving the signal due to hexavalent chromium Cr(VI) unchanged. This enables determination of the Cr(III) concentration without pre-concentration or pre-separation from chromium of other valences. The Cr(III) concentration may be measured using atomic absorption spectrometry, atomic emission spectrometry or atomic fluorescence spectrometry.

  12. Tungsten devices in analytical atomic spectrometry

    NASA Astrophysics Data System (ADS)

    Hou, Xiandeng; Jones, Bradley T.

    2002-04-01

    Tungsten devices have been employed in analytical atomic spectrometry for approximately 30 years. Most of these atomizers can be electrically heated up to 3000 °C at very high heating rates, with a simple power supply. Usually, a tungsten device is employed in one of two modes: as an electrothermal atomizer with which the sample vapor is probed directly, or as an electrothermal vaporizer, which produces a sample aerosol that is then carried to a separate atomizer for analysis. Tungsten devices may take various physical shapes: tubes, cups, boats, ribbons, wires, filaments, coils and loops. Most of these orientations have been applied to many analytical techniques, such as atomic absorption spectrometry, atomic emission spectrometry, atomic fluorescence spectrometry, laser excited atomic fluorescence spectrometry, metastable transfer emission spectroscopy, inductively coupled plasma optical emission spectrometry, inductively coupled plasma mass spectrometry and microwave plasma atomic spectrometry. The analytical figures of merit and the practical applications reported for these techniques are reviewed. Atomization mechanisms reported for tungsten atomizers are also briefly summarized. In addition, less common applications of tungsten devices are discussed, including analyte preconcentration by adsorption or electrodeposition and electrothermal separation of analytes prior to analysis. Tungsten atomization devices continue to provide simple, versatile alternatives for analytical atomic spectrometry.

  13. Human vitamin B12 absorption measurement by accelerator mass spectrometry using specifically labeled 14C-cobalamin

    PubMed Central

    Carkeet, Colleen; Dueker, Stephen R.; Lango, Jozsef; Buchholz, Bruce A.; Miller, Joshua W.; Green, Ralph; Hammock, Bruce D.; Roth, John R.; Anderson, Peter J.

    2006-01-01

    There is a need for an improved test of human ability to assimilate dietary vitamin B12. Assaying and understanding absorption and uptake of B12 is important because defects can lead to hematological and neurological complications. Accelerator mass spectrometry is uniquely suited for assessing absorption and kinetics of carbon-14 (14C)-labeled substances after oral ingestion because it is more sensitive than decay counting and can measure levels of 14C in microliter volumes of biological samples with negligible exposure of subjects to radioactivity. The test we describe employs amounts of B12 in the range of normal dietary intake. The B12 used was quantitatively labeled with 14C at one particular atom of the dimethylbenzimidazole (DMB) moiety by exploiting idiosyncrasies of Salmonella metabolism. To grow aerobically on ethanolamine, Salmonella enterica must be provided with either preformed B12 or two of its precursors, cobinamide and DMB. When provided with 14C-DMB specifically labeled in the C2 position, cells produced 14C-B12 of high specific activity (2.1 GBq/mmol, 58 mCi/mmol) (1 Ci = 37 GBq) and no detectable dilution of label from endogenous DMB synthesis. In a human kinetic study, a physiological dose (1.5 μg, 2.2 kBq/59 nCi) of purified 14C-B12 was administered and showed plasma appearance and clearance curves consistent with the predicted behavior of the pure vitamin. This method opens new avenues for study of B12 assimilation. PMID:16585531

  14. Gas chromatography-mass spectrometry analysis of essential oils from five parts of Chaihu (Radix Bupleuri Chinensis).

    PubMed

    Meng, Jie; Chen, Xingfu; Yang, Wenyu; Song, Jiuhua; Zhang, Yu; Li, Zhifei; Yang, Xingwang; Yang, Zhanguo

    2014-12-01

    To analyze the essential oils from flowers, leaves, stems, roots, and fruits of Chaihu (Radix Bupleuri Chinensis). We extracted essential oils from different parts of Chaihu (Radix Bupleuri Chinensis) using a steam distillation method. The essential oils were analyzed by gas chromatography-mass spectrometry (GC-MS). Data were collected in full scan mode (m/z 60-600). Volatile components were identified based on their retention indices and by comparing their mass spectra with those in the National Institute of Standards and Technology 2005 database, assisted by tandem mass spectrometry information. The relative content of each constituent was determined by area normalization. We identified 111 components, of which 12 were common to all 5 parts, 30 were found only in roots, 14 were found only in flowers, 6 were found only in leaves, 4 were found only in stems, and 17 were found only in fruits. Our results show that the stems, flowers, leaves, and fruits of Chaihu (Radix Bupleuri Chinensis) contain a high concentration of essential oils, and that the exact composition of the essential oils differs among the plant parts. To develop new medicines and make full use of the Chaihu (Radix Bupleuri Chinensis) resource, it is important to characterize the essential oils from different parts of the plant. In future research, it will be important to determine the pharmacological effects of the various components and the essential oil mixtures.

  15. A preconcentration system for determination of copper and nickel in water and food samples employing flame atomic absorption spectrometry.

    PubMed

    Tuzen, Mustafa; Soylak, Mustafa; Citak, Demirhan; Ferreira, Hadla S; Korn, Maria G A; Bezerra, Marcos A

    2009-03-15

    A separation/preconcentration procedure using solid phase extraction has been proposed for the flame atomic absorption spectrometric determination of copper and nickel at trace level in food samples. The solid phase is Dowex Optipore SD-2 resin contained on a minicolumn, where analyte ions are sorbed as 5-methyl-4-(2-thiazolylazo) resorcinol chelates. After elution using 1 mol L(-1) nitric acid solution, the analytes are determinate employing flame atomic absorption spectrometry. The optimization step was performed using a full two-level factorial design and the variables studied were: pH, reagent concentration (RC) and amount of resin on the column (AR). Under the experimental conditions established in the optimization step, the procedure allows the determination of copper and nickel with limit of detection of 1.03 and 1.90 microg L(-1), respectively and precision of 7 and 8%, for concentrations of copper and nickel of 200 microg L(-1). The effect of matrix ions was also evaluated. The accuracy was confirmed by analyzing of the followings certified reference materials: NIST SRM 1515 Apple leaves and GBW 07603 Aquatic and Terrestrial Biological Products. The developed method was successfully applied for the determination of copper and nickel in real samples including human hair, chicken meat, black tea and canned fish.

  16. Determination of trace concentrations of chlorine in aqueous solutions by high-resolution continuum source graphite furnace molecular absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Machyňák, Ľubomír; Čacho, František; Němeček, Martin; Beinrohr, Ernest

    2016-11-01

    Trace concentrations of total chlorine were determined by means of molecular absorption of indium mono-chloride (InCl) at 267.217 nm using high-resolution continuum source graphite furnace molecular absorption spectrometry. The effects of chemical modifiers and the amount of In on the sensitivity and accuracy were investigated. The optimum pyrolysis and vaporization temperatures were 600 °C and 1400 °C, respectively. The limit of detection and characteristic mass were found to be 0.10 ng and 0.21 ng, respectively. Potential non-spectral and spectral interferences were tested for various metals and non-metals at concentrations up to 50 mg L- 1 and for phosphoric, sulphuric and nitric acids. No spectral interferences were observed. Significant non-spectral interferences were observed with F, Br, and I at concentrations higher than 1 mg L- 1, 5 mg L- 1 and 25 mg L- 1, respectively, which is probably caused by formation of competitive indium halogen molecules. Higher concentrations of mineral acids depressed the signal owing to the formation of volatile HCl. The calibration curve was linear in the range between 0.3 and 10 ng with a correlation coefficient of R = 0.993. The elaborated method was used for the chlorine determination in various waters and a drug sample.

  17. Application of dual-cloud point extraction for the trace levels of copper in serum of different viral hepatitis patients by flame atomic absorption spectrometry: A multivariate study

    NASA Astrophysics Data System (ADS)

    Arain, Salma Aslam; Kazi, Tasneem G.; Afridi, Hassan Imran; Abbasi, Abdul Rasool; Panhwar, Abdul Haleem; Naeemullah; Shanker, Bhawani; Arain, Mohammad Balal

    2014-12-01

    An efficient, innovative preconcentration method, dual-cloud point extraction (d-CPE) has been developed for the extraction and preconcentration of copper (Cu2+) in serum samples of different viral hepatitis patients prior to couple with flame atomic absorption spectrometry (FAAS). The d-CPE procedure was based on forming complexes of elemental ions with complexing reagent 1-(2-pyridylazo)-2-naphthol (PAN), and subsequent entrapping the complexes in nonionic surfactant (Triton X-114). Then the surfactant rich phase containing the metal complexes was treated with aqueous nitric acid solution, and metal ions were back extracted into the aqueous phase, as second cloud point extraction stage, and finally determined by flame atomic absorption spectrometry using conventional nebulization. The multivariate strategy was applied to estimate the optimum values of experimental variables for the recovery of Cu2+ using d-CPE. In optimum experimental conditions, the limit of detection and the enrichment factor were 0.046 μg L-1 and 78, respectively. The validity and accuracy of proposed method were checked by analysis of Cu2+ in certified sample of serum (CRM) by d-CPE and conventional CPE procedure on same CRM. The proposed method was successfully applied to the determination of Cu2+ in serum samples of different viral hepatitis patients and healthy controls.

  18. Increasing the throughput and productivity of Caco-2 cell permeability assays using liquid chromatography-mass spectrometry: application to resveratrol absorption and metabolism.

    PubMed

    Li, Yongmei; Shin, Young Geun; Yu, Chongwoo; Kosmeder, Jerome W; Hirschelman, Wendy H; Pezzuto, John M; van Breemen, Richard B

    2003-12-01

    The Caco-2 cell monolayer permeability assay has become a standard model of human intestinal absorption and transport. This paper reviews recent progress in increasing the throughput of Caco-2 cell monolayer assays and in expanding the scope of this assay to include modeling intestinal drug metabolism. The state-of-the-art in Caco-2 cell monolayer permeability assays combines multi-well plates fitted with semi-permeable inserts on which Caco-2 cells have been cultured with liquid chromatography-mass spectrometry (LC-MS) or LC-tandem mass spectrometry (LC-MS-MS) for the quantitative analysis of test compounds and the identification of their intestinal metabolites. After reviewing the progress in increasing the throughput of Caco-2 cell monolayer assays for both modeling human intestinal permeability or transport and the metabolism of xenobiotic compounds, we demonstrate the application of LC-MS and LC-MS-MS to the measurement of resveratrol permeability and metabolism in the Caco-2 model. trans-Resveratrol (trans-3,5,4'-trihydroxystilbene) is a polyphenolic compound occurring in grapes, peanuts and other food sources, that is under investigation as a cancer chemoprevention agent. The apparent permeability coefficient for apical (AP) to basolateral (BL) movement of resveratrol was 2.0 x 10(-5)cm/sec. Resveratrol was not a substrate for P-glycoprotein or the multi-drug resistance associated proteins (MRP). No phase I metabolites were observed, but the phase II conjugates resveratrol-3-glucuronide and resveratrol-3-sulfate was identified based on LC-MS and LC-MS-MS analysis and comparison with synthetic standards. Although these data indicate that resveratrol diffuses rapidly across the intestinal epithelium, extensive phase II metabolism during absorption might reduce resveratrol bioavailability.

  19. Working towards accreditation by the International Standards Organization 15189 Standard: how to validate an in-house developed method an example of lead determination in whole blood by electrothermal atomic absorption spectrometry.

    PubMed

    Garcia Hejl, Carine; Ramirez, Jose Manuel; Vest, Philippe; Chianea, Denis; Renard, Christophe

    2014-09-01

    Laboratories working towards accreditation by the International Standards Organization (ISO) 15189 standard are required to demonstrate the validity of their analytical methods. The different guidelines set by various accreditation organizations make it difficult to provide objective evidence that an in-house method is fit for the intended purpose. Besides, the required performance characteristics tests and acceptance criteria are not always detailed. The laboratory must choose the most suitable validation protocol and set the acceptance criteria. Therefore, we propose a validation protocol to evaluate the performance of an in-house method. As an example, we validated the process for the detection and quantification of lead in whole blood by electrothermal absorption spectrometry. The fundamental parameters tested were, selectivity, calibration model, precision, accuracy (and uncertainty of measurement), contamination, stability of the sample, reference interval, and analytical interference. We have developed a protocol that has been applied successfully to quantify lead in whole blood by electrothermal atomic absorption spectrometry (ETAAS). In particular, our method is selective, linear, accurate, and precise, making it suitable for use in routine diagnostics.

  20. Graphene oxide sheets immobilized polystyrene for column preconcentration and sensitive determination of lead by flame atomic absorption spectrometry.

    PubMed

    Islam, Aminul; Ahmad, Hilal; Zaidi, Noushi; Kumar, Suneel

    2014-08-13

    A novel solid-phase extractant was synthesized by coupling graphene oxide (GO) on chloromethylated polystyrene through an ethylenediamine spacer unit to develop a column method for the preconcentration/separation of lead prior to its determination by flame atomic absorption spectrometry. It was characterized by Fourier transform infrared spectroscopy, far-infrared spectroscopy, thermogravimetric analysis/differential thermal analysis, scanning electron microscopy, energy-dispersive spectrometry, and transmission electron microscopy. The abundant oxygen-containing surface functional groups form a strong complex with lead, resulting in higher sorption capacity (227.92 mg g(-1)) than other nanosorbents used for sorption studies of the column method. Using the column procedure here is an alternative to the direct use of GO, which restricts irreversible aggregation of GO and its escape into the ecosystem, making it an environmentally sustainable method. The column method was optimized by varying experimental variables such as pH, flow rate for sorption/desorption, and elution condition and was observed to exhibit a high preconcentration factor (400) with a low preconcentration limit (2.5 ppb) and a high degree of tolerance for matrix ions. The accuracy of the proposed method was verified by determining the Pb content in the standard reference materials and by recovery experiments. The method showed good precision with a relative standard deviation <5%. The proposed method was successfully applied for the determination of lead in tap water, electroplating wastewater, river water, and food samples after preconcentration.

  1. Determination of phospholipids in soybean lecithin samples via the phosphorus monoxide molecule by high-resolution continuum source graphite furnace molecular absorption spectrometry.

    PubMed

    Pires, Laís N; Brandão, Geovani C; Teixeira, Leonardo S G

    2017-06-15

    This paper presents a method for determining phospholipids in soybean lecithin samples by phosphorus determination using high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS) via molecular absorption of phosphorus monoxide. Samples were diluted in methyl isobutyl ketone. The best conditions were found to be 213.561nm with a pyrolysis temperature of 1300°C, a volatilization temperature of 2300°C and Mg as a chemical modifier. To increase the analytical sensitivity, measurement of the absorbance signal was obtained by summing molecular transition lines for PO surrounding 213nm: 213.561, 213.526, 213.617 and 213.637nm. The limit of detection was 2.35mgg -1 and the precision, evaluated as relative standard deviation (RSD), was 2.47% (n=10) for a sample containing 2.2% (w/v) phosphorus. The developed method was applied for the analysis of commercial samples of soybean lecithin. The determined concentrations of phospholipids in the samples varied between 38.1 and 45% (w/v). Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Application of Internal Standard Method for Several 3d-Transition Metallic Elements in Flame Atomic Absorption Spectrometry Using a Multi-wavelength High-resolution Spectrometer.

    PubMed

    Toya, Yusuke; Itagaki, Toshiko; Wagatsuma, Kazuaki

    2017-01-01

    We investigated a simultaneous internal standard method in flame atomic absorption spectrometry (FAAS), in order to better the analytical precision of 3d-transition metals contained in steel materials. For this purpose, a new spectrometer system for FAAS, comprising a bright xenon lamp as the primary radiation source and a high-resolution Echelle monochromator, was employed to measure several absorption lines at a wavelength width of ca. 0.3 nm at the same time, which enables the absorbances of an analytical line and also an internal standard line to be estimated. In considering several criteria for selecting an internal standard element and the absorption line, it could be suggested that platinum-group elements: ruthenium, rhodium, or palladium, were suitable for an internal standard element to determine the 3d-transition metal elements, such as titanium, iron, and nickel, by measuring an appropriate pair of these absorption lines simultaneously. Several variances of the absorption signal, such as a variation in aspirated amounts of sample solution and a short-period drift of the primary light source, would be corrected and thus reduced, when the absorbance ratio of the analytical line to the internal standard line was measured. In Ti-Pd, Ni-Rh, and Fe-Ru systems chosen as typical test samples, the repeatability of the signal respnses was investigated with/without the internal standard method, resulting in better precision when the internal standard method was applied in the FAAS with a nitrous oxide-acetylene flame rather than an air-acetylene flame.

  3. A comparison of laser ablation-inductively coupled plasma-mass spectrometry and high-resolution continuum source graphite furnace molecular absorption spectrometry for the direct determination of bromine in polymers

    NASA Astrophysics Data System (ADS)

    de Gois, Jefferson S.; Van Malderen, Stijn J. M.; Cadorim, Heloisa R.; Welz, Bernhard; Vanhaecke, Frank

    2017-06-01

    This work describes the development and comparison of two methods for the direct determination of Br in polymer samples via solid sampling, one using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and the other using high-resolution continuum source graphite furnace molecular absorption spectrometry with direct solid sample analysis (HR-CS SS-GF MAS). The methods were optimized and their accuracy was evaluated by comparing the results obtained for 6 polymeric certified reference materials (CRMs) with the corresponding certified values. For Br determination with LA-ICP-MS, the 79Br+ signal could be monitored interference-free. For Br determination via HR-CS SS-GF MAS, the CaBr molecule was monitored at 625.315 nm with integration of the central pixel ± 1. Bromine quantification by LA-ICP-MS was performed via external calibration against a single CRM while using the 12C+ signal as an internal standard. With HR-CS SS-GF MAS, Br quantification could be accomplished using external calibration against aqueous standard solutions. Except for one LA-ICP-MS result, the concentrations obtained with both techniques were in agreement with the certified values within the experimental uncertainty as evidenced using a t-test (95% confidence level). The limit of quantification was determined to be 100 μg g- 1 Br for LA-ICP-MS and 10 μg g- 1 Br for HR-CS SS-GF MAS.

  4. Vaporization and atomization of uranium in a graphite tube electrothermal vaporizer: a mechanistic study using electrothermal vaporization inductively coupled plasma mass spectrometry and graphite furnace atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Goltz, D. M.; Grégoire, D. C.; Byrne, J. P.; Chakrabarti, C. L.

    1995-07-01

    The mechanism of vaporization and atomization of U in a graphite tube electrothermal vaporizer was studied using graphite furnace atomic absorption spectrometry (GFAAS) and electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS). Graphite furnace AAS studies indicate U atoms are formed at temperatures above 2400°C. Using ETV-ICP-MS, an appearance temperature of 1100°C was obtained indicating that some U vaporizes as U oxide. Although U carbides form at temperatures above 2000°C, ETV-ICP-MS studies show that they do not vaporize until 2600°C. In the temperature range between 2200°C and 2600°C, U atoms in GFAAS are likely formed by thermal dissociation of U oxide, whereas at higher temperatures, U atoms are formed via thermal dissociation of U carbide. The origin of U signal suppression in ETV-ICP-MS by NaCl was also investigated. At temperatures above 2000°C, signal suppression may be caused by the accelerated rate of formation of carbide species while at temperatures below 2000°C, the presence of NaCl may cause intercalation of the U in the graphite layers resulting in partial retention of U during the vaporization step. The use of 0.3% freon-23 (CHF 3) mixed with the argon carrier gas was effective in preventing the intercalation of U in graphite and U carbide formation at 2700°C.

  5. Determination of arsenic, antimony, bismuth, cadmium, copper, lead, molybdenum, silver and zinc in geological materials by atomic-absorption spectrometry

    USGS Publications Warehouse

    Viets, J.G.; O'Leary, R. M.; Clark, Robert J.

    1984-01-01

    Arsenic, antimony, bismuth, cadmium, copper, lead, molybdenum, silver and zinc are very useful elements in geochemical exploration. In the proposed method, geological samples are fused with potassium pyrosulphate and the fusate is dissolved in a solution of hydrochloric acid, ascorbic acid and potassium iodide. When this solution is shaken with a 10% V/V Aliquat 336 - isobutyl methyl ketone organic phase, the nine elements of interest are selectively partitioned in the organic phase. All nine elements can then be determined in the organic phase using flame atomic-absorption spectrometry. The method is rapid and allows the determination of Ag and Cd at levels down to 0.1 p.p.m., Cu, Mo, and Zn down to 0.5 p.p.m., Pb, Bi and Sb down to 1 p.p.m. and As down to 5 p.p.m. in geological materials.

  6. Determination of silver, bismuth, cadmium, copper, lead, and zinc in geologic materials by atomic absorption spectrometry with tricaprylylmethylammonium chloride

    USGS Publications Warehouse

    Viets, J.G.

    1978-01-01

    Interferences commonly encountered in the determination of silver, bismuth, cadmium, copper, lead, and zinc at crustal abundance levels are effectively eliminated using a rapid, sensitive, organic extraction technique. A potassium chlorate-hydrochloric acid digestion solubilizes the metals not tightly bound in the silicate lattice of rocks, soils, and stream sediments. The six metals are selectively extracted into a 10% Aliquat 336-MIBK organic phase in the presence of ascorbic acid and potassium iodide. Metals in the organic extract are determined by flame atomic absorption spectrometry to the 0.02-ppm level for silver, cadmium, copper, and zinc and to the 0.2-ppm level for bismuth and lead with a maximum relative standard deviation of 18.8% for known reference samples. An additional hydrofluoric acid digestion may be used to determine metals substituted in the silicate lattice.

  7. Chemometric evaluation of Cd, Co, Cr, Cu, Ni (inductively coupled plasma optical emission spectrometry) and Pb (graphite furnace atomic absorption spectrometry) concentrations in lipstick samples intended to be used by adults and children.

    PubMed

    Batista, Érica Ferreira; Augusto, Amanda dos Santos; Pereira-Filho, Edenir Rodrigues

    2016-04-01

    A method was developed for determining the concentrations of Cd, Co, Cr, Cu, Ni and Pb in lipstick samples intended to be used by adults and children using inductively coupled plasma optical emission spectrometry (ICP OES) and graphite furnace atomic absorption spectrometry (GF AAS) after treatment with dilute HNO3 and hot block. The combination of fractional factorial design and Desirability function was used to evaluate the ICP OES operational parameters and the regression models using Central Composite and Doehlert designs were calculated to stablish the best working condition for all analytes. Seventeen lipstick samples manufactured in different countries with different colors and brands were analyzed. Some samples contained high concentrations of toxic elements, such as Cr and Pb, which are carcinogenic and cause allergic and eczematous dermatitis. The maximum concentration detected was higher than the permissible safe limits for human use, and the samples containing these high metal concentrations were intended for use by children. Principal component analysis (PCA) was used as a chemometrics tool for exploratory analysis to observe the similarities between samples relative to the metal concentrations (a correlation between Cd and Pb was observed). Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Determination of lithium isotopes at natural abundance levels by atomic absorption spectrometry

    USGS Publications Warehouse

    Meier, A.L.

    1982-01-01

    The relationships of the absorption of 6Li and 7Li hollow cathode lamp emissions are used to determine lithium isotopic composition in the natural abundance range of geologic materials. Absorption was found to have a nonlinear dependence upon total lithium concentration and isotopic composition. A method using nonlinear equations to describe the relationship of the absorption of 6Li and 7Li lamp radiation is proposed as a means of calculating isotopic composition that is independent of total lithium concentration.

  9. Mesoporous Silica Nanoparticles as an Adsorbent for Preconcentration and Determination of Trace Amount of Nickel in Environmental Samples by Atom Trap Flame Atomic Absorption Spectrometry

    NASA Astrophysics Data System (ADS)

    Shirkhanloo, H.; Falahnejad, M.; Zavvar Mousavi, H.

    2016-01-01

    A rapid enrichment method based on solid-phase extraction (SPE) has been established for preconcentration and separation of trace Ni(II) ions in water samples prior to their determination by atom trap flame atomic absorption spectrometry. A column filled with bulky NH2-UVM7 was used as the novel adsorbent. Under optimal conditions, the linear range, limit of detection (LOD), and preconcentration factor (PF) were 3-92 μg/L, 0.8 μg/L, and 100, respectively. The validity of the method was checked by the standard reference material.

  10. Measurement of free radical kinetics in pulsed plasmas by UV and VUV absorption spectroscopy and by modulated beam mass spectrometry

    NASA Astrophysics Data System (ADS)

    Cunge, G.; Bodart, P.; Brihoum, M.; Boulard, F.; Chevolleau, T.; Sadeghi, N.

    2012-04-01

    This paper reviews recent progress in the development of time-resolved diagnostics to probe high-density pulsed plasma sources. We focus on time-resolved measurements of radicals' densities in the afterglow of pulsed discharges to provide useful information on production and loss mechanisms of free radicals. We show that broad-band absorption spectroscopy in the ultraviolet and vacuum ultraviolet spectral domain and threshold ionization modulated beam mass spectrometry are powerful techniques for the determination of the time variation of the radicals' densities in pulsed plasmas. The combination of these complementary techniques allows detection of most of the reactive species present in industrial etching plasmas, giving insights into the physico-chemistry reactions involving these species. As an example, we discuss briefly the radicals' kinetics in the afterglow of a SiCl4/Cl2/Ar discharge.

  11. In-situ pre-concentration through repeated sampling and pyrolysis for ultrasensitive determination of thallium in drinking water by electrothermal atomic absorption spectrometry.

    PubMed

    Liu, Liwei; Zheng, Huaili; Xu, Bincheng; Xiao, Lang; Chigan, Yong; Zhangluo, Yilan

    2018-03-01

    In this paper, a procedure for in-situ pre-concentration in graphite furnace by repeated sampling and pyrolysis is proposed for the determination of ultra-trace thallium in drinking water by graphite furnace atomic absorption spectrometry (GF-AAS). Without any other laborious enrichment processes that routinely result in analyte loss and contamination, thallium was directly concentrated in the graphite furnace automatically and subsequently subject to analysis. The effects of several key factors, such as the temperature for pyrolysis and atomization, the chemical modifier, and the repeated sampling times were investigated. Under the optimized conditions, a limit of detection of 0.01µgL -1 was obtained, which fulfilled thallium determination in drinking water by GB 5749-2006 regulated by China. Successful analysis of thallium in certified water samples and drinking water samples was demonstrated, with analytical results in good agreement with the certified values and those by inductively coupled plasma mass spectrometry (ICP-MS), respectively. Routine spike-recovery tests with randomly selected drinking water samples showed satisfactory results of 80-96%. The proposed method is simple and sensitive for screening of ultra-trace thallium in drinking water samples. Copyright © 2017. Published by Elsevier B.V.

  12. Application of dual-cloud point extraction for the trace levels of copper in serum of different viral hepatitis patients by flame atomic absorption spectrometry: a multivariate study.

    PubMed

    Arain, Salma Aslam; Kazi, Tasneem G; Afridi, Hassan Imran; Abbasi, Abdul Rasool; Panhwar, Abdul Haleem; Naeemullah; Shanker, Bhawani; Arain, Mohammad Balal

    2014-12-10

    An efficient, innovative preconcentration method, dual-cloud point extraction (d-CPE) has been developed for the extraction and preconcentration of copper (Cu(2+)) in serum samples of different viral hepatitis patients prior to couple with flame atomic absorption spectrometry (FAAS). The d-CPE procedure was based on forming complexes of elemental ions with complexing reagent 1-(2-pyridylazo)-2-naphthol (PAN), and subsequent entrapping the complexes in nonionic surfactant (Triton X-114). Then the surfactant rich phase containing the metal complexes was treated with aqueous nitric acid solution, and metal ions were back extracted into the aqueous phase, as second cloud point extraction stage, and finally determined by flame atomic absorption spectrometry using conventional nebulization. The multivariate strategy was applied to estimate the optimum values of experimental variables for the recovery of Cu(2+) using d-CPE. In optimum experimental conditions, the limit of detection and the enrichment factor were 0.046μgL(-1) and 78, respectively. The validity and accuracy of proposed method were checked by analysis of Cu(2+) in certified sample of serum (CRM) by d-CPE and conventional CPE procedure on same CRM. The proposed method was successfully applied to the determination of Cu(2+) in serum samples of different viral hepatitis patients and healthy controls. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Lead screening in DBS by solid sampling high-resolution continuum source graphite furnace atomic absorption spectrometry: application to newborns and pregnant women.

    PubMed

    Rello, Luis; Aramendía, Maite; Belarra, Miguel A; Resano, Martín

    2015-01-01

    DBS have become a clinical specimen especially adequate for establishing home-based collection protocols. In this work, high-resolution continuum source graphite furnace atomic absorption spectrometry is evaluated for the direct monitoring of Pb in DBS, both as a quantitative tool and a screening method. The development of the screening model is based on the establishment of the unreliability region around the threshold limits, 100 or 50 μg l(-1). More than 500 samples were analyzed to validate the model. The screening method demonstrated high sensitivity (the rate of true positives detected was always higher than 95%), an excellent LOD (1 µg l(-1)) and high throughput (10 min per sample).

  14. Discussion of parameters associated with the determination of arsenic by electrothermal atomic absorption spectrometry in slurried environmental samples.

    PubMed

    Vassileva, E; Baeten, H; Hoenig, M

    2001-01-02

    A slurry sampling-fast program procedure has been developed for the determination of arsenic in plants, soils and sediments by electrothermal atomic absorption spectrometry. Efficiencies of various single and mixed modifiers for thermal stabilization of arsenic and for a better removal of the matrix during pyrolysis step were compared. The influence of the slurry concentration, amounts of modifier and parameters of the pyrolysis step on the As integrated absorbance signals have been studied and a comparison between fast and conventional furnace programs was also made. The ultrasonic agitation of the slurry followed by a fast electrothermal program using an Ir/Mg modifier provides the most consistent performance in terms of precision and accuracy. The reliability of the whole procedure has been compared with results obtained after application of a wet digestion method with an HF step and validated by analyzing eleven certified reference materials. Arsenic detection and quantitation limits expressed on dry sample matter were about 30 and 100 micrograms kg-1, respectively.

  15. Sample preparation for arsenic speciation analysis in baby food by generation of substituted arsines with atomic absorption spectrometry detection.

    PubMed

    Huber, Charles S; Vale, Maria Goreti R; Dessuy, Morgana B; Svoboda, Milan; Musil, Stanislav; Dědina, Jiři

    2017-12-01

    A slurry sampling procedure for arsenic speciation analysis in baby food by arsane generation, cryogenic trapping and detection with atomic absorption spectrometry is presented. Several procedures were tested for slurry preparation, including different reagents (HNO 3 , HCl and tetramethylammonium hydroxide - TMAH) and their concentrations, water bath heating and ultrasound-assisted agitation. The best results for inorganic arsenic (iAs) and dimethylarsinate (DMA) were reached when using 3molL -1 HCl under heating and ultrasound-assisted agitation. The developed method was applied for the analysis of five porridge powder and six baby meal samples. The trueness of the method was checked with a certified reference material (CRM) of total arsenic (tAs), iAs and DMA in rice (ERM-BC211). Arsenic recoveries (mass balance) for all samples and CRM were performed by the determination of the tAs by inductively coupled plasma mass spectrometry (ICP-MS) after microwave-assisted digestion and its comparison against the sum of the results from the speciation analysis. The relative limits of detection were 0.44, 0.24 and 0.16µgkg -1 for iAs, methylarsonate and DMA, respectively. The concentrations of the most toxic arsenic species (iAs) in the analyzed baby food samples ranged between 4.2 and 99µgkg -1 which were below the limits of 300, 200 and 100µgkg -1 set by the Brazilian, Chinese and European legislation, respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Determination of Inorganic Arsenic in a Wide Range of Food Matrices using Hydride Generation - Atomic Absorption Spectrometry.

    PubMed

    de la Calle, Maria B; Devesa, Vicenta; Fiamegos, Yiannis; Vélez, Dinoraz

    2017-09-01

    The European Food Safety Authority (EFSA) underlined in its Scientific Opinion on Arsenic in Food that in order to support a sound exposure assessment to inorganic arsenic through diet, information about distribution of arsenic species in various food types must be generated. A method, previously validated in a collaborative trial, has been applied to determine inorganic arsenic in a wide variety of food matrices, covering grains, mushrooms and food of marine origin (31 samples in total). The method is based on detection by flow injection-hydride generation-atomic absorption spectrometry of the iAs selectively extracted into chloroform after digestion of the proteins with concentrated HCl. The method is characterized by a limit of quantification of 10 µg/kg dry weight, which allowed quantification of inorganic arsenic in a large amount of food matrices. Information is provided about performance scores given to results obtained with this method and which were reported by different laboratories in several proficiency tests. The percentage of satisfactory results obtained with the discussed method is higher than that of the results obtained with other analytical approaches.

  17. Investigation of Pb species in soils, celery and duckweed by synchrotron radiation X-ray absorption near-edge structure spectrometry

    NASA Astrophysics Data System (ADS)

    Luo, Liqiang; Shen, Yating; Liu, Jian; Zeng, Yuan

    2016-08-01

    The Pb species play a key role in its translocation in biogeochemical cycles. Soils, sediments and plants were collected from farmlands around Pb mines, and the Pb species in them was identified by X-ray absorption near-edge structure spectrometry. In soils, Pb5(PO4)3Cl and Pb3(PO4)2 were detected, and in sediments, Pb-fulvic acids (FAs) complex was identified. A Pb complex with FA fragments was also detected in celery samples. We found that (1) different Pb species were present in soils and sediments; (2) the Pb species in celery, which was grown in sediments, was different from the species present in duckweed, which grew in water; and (3) a Pb-FA-like compound was present in celery roots. The newly identified Pb species, the Pb-FA-like compound, may play a key role in Pb tolerance and translocation within plants.

  18. Cloud point extraction thermospray flame quartz furnace atomic absorption spectrometry for determination of ultratrace cadmium in water and urine

    NASA Astrophysics Data System (ADS)

    Wu, Peng; Zhang, Yunchang; Lv, Yi; Hou, Xiandeng

    2006-12-01

    A simple, low cost and highly sensitive method based on cloud point extraction (CPE) for separation/preconcentration and thermospray flame quartz furnace atomic absorption spectrometry was proposed for the determination of ultratrace cadmium in water and urine samples. The analytical procedure involved the formation of analyte-entrapped surfactant micelles by mixing the analyte solution with an ammonium pyrrolidinedithiocarbamate (APDC) solution and a Triton X-114 solution. When the temperature of the system was higher than the cloud point of Triton X-114, the complex of cadmium-PDC entered the surfactant-rich phase and thus separation of the analyte from the matrix was achieved. Under optimal chemical and instrumental conditions, the limit of detection was 0.04 μg/L for cadmium with a sample volume of 10 mL. The analytical results of cadmium in water and urine samples agreed well with those by ICP-MS.

  19. Temperature-controlled electrothermal atomization-atomic absorption spectrometry using a pyrometric feedback system in conjunction with a background monitoring device

    NASA Astrophysics Data System (ADS)

    Van Deijck, W.; Roelofsen, A. M.; Pieters, H. J.; Herber, R. F. M.

    The construction of a temperature-controlled feedback system for electrothermal atomization-atomic absorption spectrometry (ETA-AAS) using an optical pyrometer applied to the atomization stage is described. The system was used in conjunction with a fast-response background monitoring device. The heating rate of the furnace amounted to 1400° s -1 with a reproducibility better than 1%. The precision of the temperature control at a steady state temperature of 2000°C was 0.1%. The analytical improvements offered by the present system have been demonstrated by the determination of cadmium and lead in blood and finally by the determination of lead in serum. Both the sensitivity and the precision of the method have been improved. The accuracy of the method was checked by determining the lead content for a number of scrum samples both by ETA-AAS and differential pulse anodic stripping voltametry (DPASV) and proved to be satisfactory.

  20. Mass spectrometry in grape and wine chemistry. Part II: The consumer protection.

    PubMed

    Flamini, Riccardo; Panighel, Annarita

    2006-01-01

    Controls in food industry are fundamental to protect the consumer health. For products of high quality, warranty of origin and identity is required and analytical control is very important to prevent frauds. In this article, the "state of art" of mass spectrometry in enological chemistry as a consumer safety contribute is reported. Gas chromatography-mass spectrometry (GC/MS) and liquid-chromatography-mass spectrometry (LC/MS) methods have been developed to determine pesticides, ethyl carbamate, and compounds from the yeast and bacterial metabolism in wine. The presence of pesticides in wine is mainly linked to the use of dicarboxyimide fungicides on vineyard shortly before the harvest to prevent the Botrytis cinerea attack of grape. Pesticide residues are regulated at maximum residue limits in grape of low ppm levels, but significantly lower levels in wine have to be detected, and mass spectrometry offers effective and sensitive methods. Moreover, mass spectrometry represent an advantageous alternative to the radioactive-source-containing electron capture detector commonly used in GC analysis of pesticides. Analysis of ochratoxin A (OTA) in wine by LC/MS and multiple mass spectrometry (MS/MS) permits to confirm the toxin presence without the use of expensive immunoaffinity columns, or time and solvent consuming sample derivatization procedures. Inductively coupled plasma-mass spectrometry (ICP/MS) is used to control heavy metals contamination in wine, and to verify the wine origin and authenticity. Isotopic ratio-mass spectrometry (IRMS) is applied to reveal wine watering and sugar additions, and to determine the product origin and traceability.

  1. Use of High-Resolution Continuum Source Flame Atomic Absorption Spectrometry (HR-CS FAAS) for Sequential Multi-Element Determination of Metals in Seawater and Wastewater Samples

    NASA Astrophysics Data System (ADS)

    Peña-Vázquez, E.; Barciela-Alonso, M. C.; Pita-Calvo, C.; Domínguez-González, R.; Bermejo-Barrera, P.

    2015-09-01

    The objective of this work is to develop a method for the determination of metals in saline matrices using high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS). Module SFS 6 for sample injection was used in the manual mode, and flame operating conditions were selected. The main absorption lines were used for all the elements, and the number of selected analytical pixels were 5 (CP±2) for Cd, Cu, Fe, Ni, Pb and Zn, and 3 pixels for Mn (CP±1). Samples were acidified (0.5% (v/v) nitric acid), and the standard addition method was used for the sequential determination of the analytes in diluted samples (1:2). The method showed good precision (RSD(%) < 4%, except for Pb (6.5%)) and good recoveries. Accuracy was checked after the analysis of an SPS-WW2 wastewater reference material diluted with synthetic seawater (dilution 1:2), showing a good agreement between certified and experimental results.

  2. Speciation of organic and inorganic selenium in selenium-enriched rice by graphite furnace atomic absorption spectrometry after cloud point extraction.

    PubMed

    Sun, Mei; Liu, Guijian; Wu, Qianghua

    2013-11-01

    A new method was developed for the determination of organic and inorganic selenium in selenium-enriched rice by graphite furnace atomic absorption spectrometry detection after cloud point extraction. Effective separation of organic and inorganic selenium in selenium-enriched rice was achieved by sequentially extracting with water and cyclohexane. Under the optimised conditions, the limit of detection (LOD) was 0.08 μg L(-1), the relative standard deviation (RSD) was 2.1% (c=10.0 μg L(-1), n=11), and the enrichment factor for selenium was 82. Recoveries of inorganic selenium in the selenium-enriched rice samples were between 90.3% and 106.0%. The proposed method was successfully applied for the determination of organic and inorganic selenium as well as total selenium in selenium-enriched rice. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Determination of cadmium in coal using solid sampling graphite furnace high-resolution continuum source atomic absorption spectrometry.

    PubMed

    da Silva, Alessandra Furtado; Borges, Daniel L G; Lepri, Fábio Grandis; Welz, Bernhard; Curtius, Adilson J; Heitmann, Uwe

    2005-08-01

    This work describes the development of a method to determine cadmium in coal, in which iridium is used as a permanent chemical modifier and calibration is performed against aqueous standards by high-resolution continuum source atomic absorption spectrometry (HR-CS AAS). This new instrumental concept makes the whole spectral environment in the vicinity of the analytical line accessible, providing a lot more data than just the change in absorbance over time available from conventional instruments. The application of Ir (400 microg) as a permanent chemical modifier, thermally deposited on the pyrolytic graphite platform surface, allowed pyrolysis temperatures of 700 degrees C to be used, which was sufficiently high to significantly reduce the continuous background that occurred before the analyte signal at pyrolysis temperatures <700 degrees C. Structured background absorption also occurred after the analyte signal when atomization temperatures of >1600 degrees C were used, which arose from the electron-excitation spectrum (with rotational fine structure) of a diatomic molecule. Under optimized conditions (pyrolysis at 700 degrees C and atomization at 1500 degrees C), interference-free determination of cadmium in seven certified coal reference materials and two real samples was achieved by direct solid sampling and calibrating against aqueous standards, resulting in good agreement with the certified values (where available) at the 95% confidence level. A characteristic mass of 0.4 pg and a detection limit of 2 ng g(-1), calculated for a sample mass of 1.0 mg coal, was obtained. A precision (expressed as the relative standard deviation, RSD) of <10% was typically obtained when coal samples in the mass range 0.6-1.2 mg were analyzed.

  4. Rapid food decomposition by H2O2-H2SO4 for determination of total mercury by flow injection cold vapor atomic absorption spectrometry.

    PubMed

    Zenebon, Odair; Sakuma, Alice M; Dovidauskas, Sergio; Okada, Isaura A; de, MaioFrancaD; Lichtig, Jaim

    2002-01-01

    A mixture of 50% H2O2-H2SO4 (3 + 1, v/v) was used for decomposition of food in open vessels at 80 degrees C. The treatment allowed rapid total mercury determination by flow injection cold vapor atomic absorption spectrometry. Cabbage, potatoes, peanuts paste, hazelnuts paste, oats, tomatoes and their derivatives, oysters, shrimps, prawns, shellfish, marine algae, and many kinds of fish were analyzed by the proposed methodology with a limit of quantitation of 0.86 +/- 0.08 microg/L mercury in the final solution. Reference materials tested also gave excellent recovery.

  5. The determination of lead in sugar and sweets without digestion by electrothermal atomic absorption spectrometry (ETAAS) with a rhodium chemical modifier.

    PubMed

    Dias, V M C; Cardoso, A S B

    2006-05-01

    Reference methods for determining lead in food are usually time-consuming. This paper reports a straightforward procedure using electrothermal atomic absorption spectrometry (ETAAS), to determine lead (Pb) in fat-free sweets. Several chemical modifiers were examined and results showed that it is not necessary to digest the samples, when a rhodium (Rh) modifier was used. The samples were dissolved in nitric acid and the determination of Pb was performed by ETAAS, using Rh chemical modifier at a pyrolysis temperature of 900 degrees C and an atomization temperature of 1,500 degrees C. No ashing step was employed and aqueous standards were used, in the range 2-10 microg l(-1). The limit of quantification was 0.095 mg kg(-1), and the accuracy of the method was verified by analysing certified reference materials.

  6. On-line preconcentration system for lead(II) determination in waste water by atomic absorption spectrometry using active carbon loaded with Pyrogallol Red.

    PubMed

    Ensafi, Ali A; Khayamian, Taghi; Karbasi, Mohammad H

    2003-06-01

    An on-line system for enrichment and determination of lead(II) is presented. It is based on the adsorption of lead(II) ions on a minicolumn packed with active carbon loaded with Pyrogallol Red. After preconcentration step, the metal ions are eluted automatically by 5.0 ml of 0.50 M nitric acid solution and the lead ion contents were determined by atomic absorption spectrometry. The influence of chemicals, pH and flow variables were studied as well as effect of potential interfering ions. Under the optimum conditions, the lead ions in aqueous samples were concentrated about 100 fold by the column. The detection limit was 0.001 microg ml(-1). The recovery percent of spliced lead(II) was in the range of 98%-103%.

  7. Review on Ion Mobility Spectrometry. Part 1: Current Instrumentation

    PubMed Central

    Cumeras, R.; Figueras, E.; Davis, C.E.; Baumbach, J.I.; Gràcia, I.

    2014-01-01

    Ion Mobility Spectrometry (IMS) is a widely used and ‘well-known’ technique of ion separation in gaseous phase based on the differences of ion mobilities under an electric field. All IMS instruments operate with an electric field that provides space separation, but some IMS instruments also operate with a drift gas flow which provides also a temporal separation. In this review we will summarize the current IMS instrumentation. IMS techniques have received an increased interest as new instrumentation has become available to be coupled with mass spectrometry (MS). For each of the eight types of IMS instruments reviewed it is mentioned whether they can be hyphenated with MS and whether they are commercially available. Finally, out of the described devices, the six most-consolidated ones are compared. The current review article is followed by a companion review article which details the IMS hyphenated techniques (mainly gas chromatography and mass spectrometry) and the factors that make the data from an IMS device change as function of device parameters and sampling conditions. These reviews will provide the reader with an insightful view of the main characteristics and aspects of the IMS technique. PMID:25465076

  8. Paroxetine decreased plasma exposure of glyburide partly via inhibiting intestinal absorption in rats.

    PubMed

    Jiang, Shuwen; Zhao, Weiman; Chen, Yang; Zhong, Zeyu; Zhang, Mian; Li, Feng; Xu, Ping; Zhao, Kaijing; Li, Ying; Liu, Li; Liu, Xiaodong

    2015-06-01

    Accumulating evidences have shown that diabetes is often accompanied with depression, thus it is possible that oral antidiabetic agent glyburide and antidepressive agent paroxetine are co-administered in diabetic patients. The aim of this study was to assess interactions between glyburide and paroxetine in rats. Effect of paroxetine on pharmacokinetics of orally administered glyburide was investigated. Effect of naringin (NAR), an inhibitor of rat intestinal organic anion transporting polypeptides 1a5 (Oatp1a5), on pharmacokinetics of glyburide was also studied. The results showed that co-administration of paroxetine markedly reduced plasma exposure and prolonged Tmax of glyburide, accompanied by significant increase in fecal excretion of glyburide. Co-administration of naringin also significantly decreased plasma exposure of glyburide. Data from intestinal perfusion experiments showed that both paroxetine and naringin significantly inhibited intestinal absorption of glyburide. Caco-2 cells were used to investigate whether paroxetine and naringin affected intestinal transport of glyburide and fexofenadine (a substrate of Oatp1a5). The results showed that both paroxetine and naringin greatly inhibited absorption of glyburide and fexofenadine. All results gave a conclusion that co-administration of paroxetine decreased plasma exposure of glyburide in rats via inhibiting intestinal absorption of glyburide, which may partly be attributed to the inhibition of intestinal Oatp1a5 activity. Copyright © 2015 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.

  9. Development and Validation of a Sensitive Method for Trace Nickel Determination by Slotted Quartz Tube Flame Atomic Absorption Spectrometry After Dispersive Liquid-Liquid Microextraction.

    PubMed

    Yolcu, Şükran Melda; Fırat, Merve; Chormey, Dotse Selali; Büyükpınar, Çağdaş; Turak, Fatma; Bakırdere, Sezgin

    2018-05-01

    In this study, dispersive liquid-liquid microextraction was systematically optimized for the preconcentration of nickel after forming a complex with diphenylcarbazone. The measurement output of the flame atomic absorption spectrometer was further enhanced by fitting a custom-cut slotted quartz tube to the flame burner head. The extraction method increased the amount of nickel reaching the flame and the slotted quartz tube increased the residence time of nickel atoms in the flame to record higher absorbance. Two methods combined to give about 90 fold enhancement in sensitivity over the conventional flame atomic absorption spectrometry. The optimized method was applicable over a wide linear concentration range, and it gave a detection limit of 2.1 µg L -1 . Low relative standard deviations at the lowest concentration in the linear calibration plot indicated high precision for both extraction process and instrumental measurements. A coal fly ash standard reference material (SRM 1633c) was used to determine the accuracy of the method, and experimented results were compatible with the certified value. Spiked recovery tests were also used to validate the applicability of the method.

  10. Simultaneous preconcentration of cadmium and lead in water samples with silica gel and determination by flame atomic absorption spectrometry.

    PubMed

    Xu, Hongbo; Wu, Yun; Wang, Jian; Shang, Xuewei; Jiang, Xiaojun

    2013-12-01

    A new method that utilizes pretreated silica gel as an adsorbent has been developed for simultaneous preconcentration of trace Cd(II) and Pb(II) prior to the measurement by flame atomic absorption spectrometry. The effects of pH, the shaking time, the elution condition and the coexisting ions on the separation/preconcentration conditions of analytes were investigated. Under optimized conditions, the static adsorption capacity of Cd(II) and Pb(II) were 45.5 and 27.1mg/g, the relative standard deviations were 3.2% and 1.7% (for n = 11), and the limits of detection obtained were 4.25 and 0.60 ng/mL, respectively. The method was validated by analyzing the certified reference materials GBW 07304a (stream sediment) and successfully applied to the analysis of various treated wastewater samples with satisfactory results. Copyright © 2013 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  11. CaI and SrI molecules for iodine determination by high-resolution continuum source graphite furnace molecular absorption spectrometry: Greener molecules for practical application.

    PubMed

    Zanatta, Melina Borges Teixeira; Nakadi, Flávio Venâncio; da Veiga, Márcia Andreia Mesquita Silva

    2018-03-01

    A new method to determine iodine in drug samples by high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS) has been developed. The method measures the molecular absorption of a diatomic molecule, CaI or SrI (less toxic molecule-forming reagents), at 638.904 or 677.692nm, respectively, and uses a mixture containing 5μg of Pd and 0.5μg of Mg as chemical modifier. The method employs pyrolysis temperatures of 1000 and 800°C and vaporization temperatures of 2300 and 2400°C for CaI and SrI, respectively. The optimized amounts of Ca and Sr as molecule-forming reagents are 100 and 150µg, respectively. On the basis of interference studies, even small chlorine concentrations reduce CaI and SrI absorbance significantly. The developed method was used to analyze different commercial drug samples, namely thyroid hormone pills with three different iodine amounts (15.88, 31.77, and 47.66µg) and one liquid drug with 1% m v -1 active iodine in their compositions. The results agreed with the values informed by the manufacturers (95% confidence level) regardless of whether CaI or SrI was determined. Therefore, the developed method is useful for iodine determination on the basis of CaI or SrI molecular absorption. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Solvent microextraction-flame atomic absorption spectrometry (SME-FAAS) for determination of ultratrace amounts of cadmium in meat and fish samples.

    PubMed

    Goudarzi, Nasser

    2009-02-11

    A simple, low cost and highly sensitive method based on solvent microextraction (SME) for separation/preconcentration and flame atomic absorption spectrometry (FAAS) was proposed for the determination of ultratrace amounts of cadmium in meat and fish samples. The analytical procedure involved the formation of a hydrophobic complex by mixing the analyte solution with an ammonium pyrrolidinedithiocarbamate (APDC) solution. In suitable conditions, the complex of cadmium-APDC entered the micro organic phase, and thus, separation of the analyte from the matrix was achieved. Under optimal chemical and instrumental conditions, a detection limit (3 sigma) of 0.8 ng L(-1) and an enrichment factor of 93 were achieved. The relative standard deviation for the method was found to be 2.2% for Cd. The interference effects of some anions and cations were also investigated. The developed method has been applied to the determination of trace Cd in meat and fish samples.

  13. [Determination of metals in waste bag filter of steel works by microwave digestion-flame atomic absorption spectrometry].

    PubMed

    Ning, Xun-An; Zhou, Yun; Liu, Jing-Yong; Wang, Jiang-Hui; Li, Lei; Ma, Xiao-Guo

    2011-09-01

    A method of microwave digestion technique-flame atomic absorption spectrometry was proposed to determine the total contents of Cu, Zn, Pb, Cd, Cr and Ni in five different kinds of waste bag filters from a steel plant. The digestion effects of the six acid systems on the heavy metals digestion were studied for the first time. The relative standard deviation (RSD) of the method was between 1.02% and 9.35%, and the recovery rates obtained by standard addition method ranged from 87.7% to 105.6%. The results indicated that the proposed method exhibited the advantages of simplicity, speediness, accuracy and repeatability, and it was suitable for determining the metal elements of the waste bag filter. The results also showed that different digestion systems should be used according to different waste bag filters. The waste bag filter samples from different production processes had different metal elements content. The Pb and Zn were the highest in the waste bag filters, while the Cu, Ni, Cd and Cr were relatively lower. These determination results provided the scientific data for further treatment and disposal of the waste bag filter.

  14. Preconcentration of lead using solidification of floating organic drop and its determination by electrothermal atomic absorption spectrometry

    PubMed Central

    Chamsaz, Mahmoud; Akhoundzadeh, Jeiran; Arbab-zavar, Mohammad Hossein

    2012-01-01

    A simple microextraction method based on solidification of a floating organic drop (SFOD) was developed for preconcentration of lead prior to its determination by electrothermal atomic absorption spectrometry (ETAAS). Ammonium pyrolidinedithiocarbamate (APDC) was used as complexing agent, and the formed complex was extracted into a 20 μL of 1-undecanol. The extracted complex was diluted with ethanol and injected into a graphite furnace. An orthogonal array design (OAD) with OA16 (45) matrix was employed to study the effects of different parameters such as pH, APDC concentration, stirring rate, sample solution temperature and the exposure time on the extraction efficiency. Under the optimized experimental conditions the limit of detection (based on 3 s) and the enhancement factor were 0.058 μg L−1 and 113, respectively. The relative standard deviation (RSD) for 8 replicate determinations of 1 μg L−1 of Pb was 8.8%. The developed method was validated by the analysis of certified reference materials and was successfully applied to the determination of lead in water and infant formula base powder samples. PMID:25685441

  15. Use of atomic absorption spectrometry in assessment of biomonitor plants for lead, cadmium and copper pollution.

    PubMed

    Gokce, Kaya; Mehmet, Yaman

    2012-01-01

    Eleven plant species were collected from the vicinity of lead-battery plant in the city of Gaziantep, Turkey. Lead, cadmium and copper concentrations in the soil and leaves of plants were determined by atomic absorption spectrometry. Lead, Cd and Cu concentrations in the soil samples taken from battery area were found to be in the ranges of 304-602, 0.4-0.44 and 31-37 mg x kg(-1), respectively. Significantly increased lead concentration up to 2 750 mg x kg(-1) was found in the leaves of Eleagnus angustifolia L. plant. The lead concentrations in the other plant leaves taken from 50 m around battery factory followed the order Ailanthus altissima > Morus sp. > Juglans regia L. > Ficus carica L. > Cydonia oblonga Miller > Prunus x domestica L. The plants, Populus nigra L. , Eleagnus angustifolia L. and Salix sp. were found useful for Cd, and the plant, Eleagnus angusti folia L. for Pb, to be considered as potential biomonitor. Especially, leaves of trees and plants taken from the distance of 50 m from battery plant have relatively higher Pb concentrations. Therefore, people who and animals which live in this area and benefit from these soil and plants have vital risks.

  16. Detection of silver nanoparticles in parsley by solid sampling high-resolution-continuum source atomic absorption spectrometry.

    PubMed

    Feichtmeier, Nadine S; Leopold, Kerstin

    2014-06-01

    In this work, we present a fast and simple approach for detection of silver nanoparticles (AgNPs) in biological material (parsley) by solid sampling high-resolution-continuum source atomic absorption spectrometry (HR-CS AAS). A novel evaluation strategy was developed in order to distinguish AgNPs from ionic silver and for sizing of AgNPs. For this purpose, atomisation delay was introduced as significant indication of AgNPs, whereas atomisation rates allow distinction of 20-, 60-, and 80-nm AgNPs. Atomisation delays were found to be higher for samples containing silver ions than for samples containing silver nanoparticles. A maximum difference in atomisation delay normalised by the sample weight of 6.27 ± 0.96 s mg(-1) was obtained after optimisation of the furnace program of the AAS. For this purpose, a multivariate experimental design was used varying atomisation temperature, atomisation heating rate and pyrolysis temperature. Atomisation rates were calculated as the slope of the first inflection point of the absorbance signals and correlated with the size of the AgNPs in the biological sample. Hence, solid sampling HR-CS AAS was proved to be a promising tool for identifying and distinguishing silver nanoparticles from ionic silver directly in solid biological samples.

  17. Evaluation of the memory effect on gold-coated silica adsorption tubes used for the analysis of gaseous mercury by cold vapor atomic absorption spectrometry.

    PubMed

    Rahman, Mohammad Mahmudur; Brown, Richard J C; Kim, Ki-Hyun; Yoon, Hye-On; Phan, Nhu-Thuc

    2013-01-01

    In an effort to reduce the experimental bias involved in the analysis of gaseous elemental mercury (Hg(o)), the blank response from gold-coated adsorption tubes has been investigated using cold vapor atomic absorption spectrometry (CVAAS). Our study has been compared with our recent investigation on memory effect in a cold vapour atomic fluorescence spectrometry (CVAFS). The pattern of blank responses was quantified after loading different amounts of mercury and after different time intervals of 1, 14, and 45 days. In case of the one day interval, the result of five to six instant blank heating cycles confirmed successful liberation of mercury following the second and third blank heating cycles. The results of 14 or 45 days generally suggest that liberation of excess mercury is affected by both the initial loading amount and the length of storage time prior to analysis. We have demonstrated a possibly effective way to reduce memory effects. Some similarities of these results with those from CVAFS experiment suggests that the blank response is caused by a combination of mercury absorbed within the bulk gold and micro- and nanoparticles liberated during heating and not from coabsorbing interfering gaseous species.

  18. Evaluation of the Memory Effect on Gold-Coated Silica Adsorption Tubes Used for the Analysis of Gaseous Mercury by Cold Vapor Atomic Absorption Spectrometry

    PubMed Central

    Rahman, Mohammad Mahmudur; Brown, Richard J. C.; Yoon, Hye-On; Phan, Nhu-Thuc

    2013-01-01

    In an effort to reduce the experimental bias involved in the analysis of gaseous elemental mercury (Hgo), the blank response from gold-coated adsorption tubes has been investigated using cold vapor atomic absorption spectrometry (CVAAS). Our study has been compared with our recent investigation on memory effect in a cold vapour atomic fluorescence spectrometry (CVAFS). The pattern of blank responses was quantified after loading different amounts of mercury and after different time intervals of 1, 14, and 45 days. In case of the one day interval, the result of five to six instant blank heating cycles confirmed successful liberation of mercury following the second and third blank heating cycles. The results of 14 or 45 days generally suggest that liberation of excess mercury is affected by both the initial loading amount and the length of storage time prior to analysis. We have demonstrated a possibly effective way to reduce memory effects. Some similarities of these results with those from CVAFS experiment suggests that the blank response is caused by a combination of mercury absorbed within the bulk gold and micro- and nanoparticles liberated during heating and not from coabsorbing interfering gaseous species. PMID:23589708

  19. Determination of mercury distribution inside spent compact fluorescent lamps by atomic absorption spectrometry

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rey-Raap, Natalia; Gallardo, Antonio, E-mail: gallardo@emc.uji.es

    Highlights: Black-Right-Pointing-Pointer New treatments for CFL are required considering the aim of Directive 202/96/CE. Black-Right-Pointing-Pointer It is shown that most of the mercury introduced into a CFL is in the phosphor powder. Black-Right-Pointing-Pointer Experimental conditions for microwave-assisted sample digestion followed by AAS measurements are described. Black-Right-Pointing-Pointer By washing the glass it is possible to reduce the concentration below legal limits. - Abstract: In this study, spent compact fluorescent lamps were characterized to determine the distribution of mercury. The procedure used in this research allowed mercury to be extracted in the vapor phase, from the phosphor powder, and the glass matrix.more » Mercury concentration in the three phases was determined by the method known as cold vapor atomic absorption spectrometry. Median values obtained in the study showed that a compact fluorescent lamp contained 24.52 {+-} 0.4 ppb of mercury in the vapor phase, 204.16 {+-} 8.9 ppb of mercury in the phosphor powder, and 18.74 {+-} 0.5 ppb of mercury in the glass matrix. There are differences in mercury concentration between the lamps since the year of manufacture or the hours of operation affect both mercury content and its distribution. The 85.76% of the mercury introduced into a compact fluorescent lamp becomes a component of the phosphor powder, while more than 13.66% is diffused through the glass matrix. By washing and eliminating all phosphor powder attached to the glass surface it is possible to classified the glass as a non-hazardous waste.« less

  20. Determination of calcium, magnesium and zinc in lubricating oils by flame atomic absorption spectrometry using a three-component solution.

    PubMed

    Zmozinski, Ariane V; de Jesus, Alexandre; Vale, Maria G R; Silva, Márcia M

    2010-12-15

    Lubricating oils are used to decrease wear and friction of movable parts of engines and turbines, being in that way essential for the performance and the increase of that equipment lifespan. The presence of some metals shows the addition of specific additives such as detergents, dispersals and antioxidants that improve the performance of these lubricants. In this work, a method for determination of calcium, magnesium and zinc in lubricating oil by flame atomic absorption spectrometry (F AAS) was developed. The samples were diluted with a small quantity of aviation kerosene (AVK), n-propanol and water to form a three-component solution before its introduction in the F AAS. Aqueous inorganic standards diluted in the same way have been used for calibration. To assess the accuracy of the new method, it was compared with ABNT NBR 14066 standard method, which consists in diluting the sample with AVK and in quantification by F AAS. Two other validating methods have also been used: the acid digestion and the certified reference material NIST (SRM 1084a). The proposed method provides the following advantages in relation to the standard method: significant reduction of the use of AVK, higher stability of the analytes in the medium and application of aqueous inorganic standards for calibration. The limits of detection for calcium, magnesium and zinc were 1.3 μg g(-1), 0.052 μg g(-1) and 0.41 μg g(-1), respectively. Concentrations of calcium, magnesium and zinc in six different samples obtained by the developed method did not differ significantly from the results obtained by the reference methods at the 95% confidence level (Student's t-test and ANOVA). Therefore, the proposed method becomes an efficient alternative for determination of metals in lubricating oil. Copyright © 2010 Elsevier B.V. All rights reserved.

  1. Determination and Uncertainty Analysis of Inorganic Arsenic in Husked Rice by Solid Phase Extraction and Atomic Absorption Spectrometry with Hydride Generation.

    PubMed

    Saxena, Sushil Kumar; Karipalli, Agnes Raju; Krishnan, Anoop A; Rangasamy, Rajesh; Malekadi, Praveen; Singh, Dhirendra P; Vasu, Vimesh; Singh, Vijay K

    2017-05-01

    This study enables the selective determination of inorganic arsenic (iAs) with a low detection limit using an economical instrument [atomic absorption spectrometer with hydride generation (HG)] to meet the regulatory requirements as per European Commission (EC) and Codex guidelines. Dry rice samples (0.5 g) were diluted using 0.1 M HNO3-3% H2O2 and heated in a water bath (90 ± 2°C) for 60 min. Through this process, all the iAs is solubilized and oxidized to arsenate [As(V)]. The centrifuged extract was loaded onto a preconditioned and equilibrated strong anion-exchange SPE column (silica-based Strata SAX 500 mg/6 mL), followed by selective and sequential elution of As(V), enabling the selective quantification of iAs using atomic absorption spectrometry with HG. In-house validation showed a mean recovery of 94% and an LOQ of 0.025 mg/kg. The repeatability (HorRatr) and reproducibility (HorRatR) values were <2, meeting the performance criteria mandated by the EC. The combined standard measurement uncertainty by this method was less than the maximum standard measurement uncertainty; thus, the method can be considered for official control purposes. The method was applied for the determination of iAs in husked rice samples and has potential applications in other food commodities.

  2. Introduction of organic/hydro-organic matrices in inductively coupled plasma optical emission spectrometry and mass spectrometry: a tutorial review. Part I. Theoretical considerations.

    PubMed

    Leclercq, Amélie; Nonell, Anthony; Todolí Torró, José Luis; Bresson, Carole; Vio, Laurent; Vercouter, Thomas; Chartier, Frédéric

    2015-07-23

    Due to their outstanding analytical performances, inductively coupled plasma optical emission spectrometry (ICP-OES) and mass spectrometry (ICP-MS) are widely used for multi-elemental measurements and also for isotopic characterization in the case of ICP-MS. While most studies are carried out in aqueous matrices, applications involving organic/hydro-organic matrices become increasingly widespread. This kind of matrices is introduced in ICP based instruments when classical "matrix removal" approaches such as acid digestion or extraction procedures cannot be implemented. Due to the physico-chemical properties of organic/hydro-organic matrices and their associated effects on instrumentation and analytical performances, their introduction into ICP sources is particularly challenging and has become a full topic. In this framework, numerous theoretical and phenomenological studies of these effects have been performed in the past, mainly by ICP-OES, while recent literature is more focused on applications and associated instrumental developments. This tutorial review, divided in two parts, explores the rich literature related to the introduction of organic/hydro-organic matrices in ICP-OES and ICP-MS. The present Part I, provides theoretical considerations in connection with the physico-chemical properties of organic/hydro-organic matrices, in order to better understand the induced phenomena. This focal point is divided in four chapters highlighting: (i) the impact of organic/hydro-organic matrices from aerosol generation to atomization/excitation/ionization processes; (ii) the production of carbon molecular constituents and their spatial distribution in the plasma with respect to analytes repartition; (iii) the subsequent modifications of plasma fundamental properties; and (iv) the resulting spectroscopic and non spectroscopic interferences. This first part of this tutorial review is addressed either to beginners or to more experienced scientists who are interested in the

  3. Determination of tellurium by hydride generation with in situ trapping flame atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Matusiewicz, Henryk; Krawczyk, Magdalena

    2007-03-01

    The analytical performance of coupled hydride generation — integrated atom trap (HG-IAT) atomizer flame atomic absorption spectrometry (FAAS) system was evaluated for determination of Te in reference material (GBW 07302 Stream Sediment), coal fly ash and garlic. Tellurium, using formation of H 2Te vapors, is atomized in air-acetylene flame-heated IAT. A new design HG-IAT-FAAS hyphenated technique that would exceed the operational capabilities of existing arrangements (a water-cooled single silica tube, double-slotted quartz tube or an "integrated trap") was investigated. An improvement in detection limit was achieved compared with using either of the above atom trapping techniques separately. The concentration detection limit, defined as 3 times the blank standard deviation (3 σ), was 0.9 ng mL - 1 for Te. For a 2 min in situ pre-concentration time (sample volume of 2 mL), sensitivity enhancement compared to flame AAS, was 222 fold, using the hydride generation — atom trapping technique. The sensitivity can be further improved by increasing the collection time. The precision, expressed as RSD, was 7.0% ( n = 6) for Te. The designs studied include slotted tube, single silica tube and integrated atom trap-cooled atom traps. The accuracy of the method was verified using a certified reference material (GBW 07302 Stream Sediment) by aqueous standard calibration curves. The measured Te contents of the reference material was in agreement with the information value. The method was successfully applied to the determination of tellurium in coal fly ash and garlic.

  4. Ligandless dispersive liquid--liquid microextraction of iron in biological and foodstuff samples and its determination by Electrothermal atomic absorption spectrometry.

    PubMed

    Madadizadeh, Mohadeseh; Taher, Mohammad Ali; Ashkenani, Hamid

    2013-01-01

    A new, simple, and efficient method comprising ligandless dispersive liquid-liquid microextraction combined with electrothermal atomic absorption spectrometry is reported for the preconcentration and determination of ultratrace amounts of Fe(III). Carbon tetrachloride and acetone were used as the extraction and disperser solvents, respectively. Some effective parameters of the microextraction such as choice of extraction and disperser solvents, their volume, extraction time and temperature, salt and surfactant effect, and pH were optimized. Under the optimum conditions, the calibration curve was linear in the range of 0.02 to 0.46 microg/L of Fe(III), with LOD and LOQ of 5.2 and 17.4 ng/L, respectively. The RSD for seven replicated determinations of Fe(IIl) ion at 0.1 microg/L concentration level was 5.2%. Operational simplicity, rapidity, low cost, good repeatability, and low consumption of extraction solvent are the main advantages of the proposed method. The method was successfully applied to the determination of iron in biological, food, and certified reference samples.

  5. Copper absorption from foods labelled intrinsically and extrinsically with Cu-65 stable isotope.

    PubMed

    Harvey, L J; Dainty, J R; Beattie, J H; Majsak-Newman, G; Wharf, S G; Reid, M D; Fairweather-Tait, S J

    2005-03-01

    To determine copper absorption from copper containing foods labelled either intrinsically or extrinsically with a highly enriched Cu-65 stable isotope label. A longitudinal cross-over study. The study was conducted at the Institute of Food Research, Human Nutrition Unit, Norwich, UK. Subjects were recruited locally via advertisements placed around the Norwich Research Park. A total of 10 volunteers (nine female, one male) took part in the study, but not all volunteers completed each of the test meals. A highly enriched Cu-65 stable isotope label was administered to volunteers in the form of a reference dose or in breakfast test meals consisting of red wine, soya beans, mushrooms or sunflower seeds. Faecal monitoring and mass spectrometry techniques were used to estimate the relative quantities of copper absorbed from the different test meals. True copper absorption from the reference dose (54%) was similar to extrinsically labelled red wine (49%) and intrinsically labelled sunflower seeds (52%), but significantly higher than extrinsically labelled mushrooms (35%), intrinsically (29%) and extrinsically (15%) labelled soya beans and extrinsically labelled sunflower seed (32%) test meals. The use of Cu-65 extrinsic labels in copper absorption studies requires validation according to the food being examined; intrinsic and extrinsic labelling produced significantly different results for sunflower seeds.

  6. Determination of lead in flour samples directly by solid sampling high resolution continuum source graphite furnace atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Tinas, Hande; Ozbek, Nil; Akman, Suleyman

    2018-02-01

    In this study, lead concentrations in various flour samples were determined by high-resolution continuum source graphite furnace atomic absorption spectrometry with solid sampling. Since samples were analyzed directly, the risks and disadvantages of sample digestion were eliminated. Solid flour samples were dried, weighed on the platforms, Pd was added as a modifier and introduced directly into a graphite tube using a manual solid sampler. Platforms and tubes were coated with Zr. The optimized pyrolysis and atomization temperatures were 800 °C and 2200 °C, respectively. The sensitivities of lead in various flour certified reference materials (CRMs) and aqueous standards were not significantly different. Therefore, aqueous standards were safely used for calibration. The absolute limit of detection and characteristic mass were 7.2 pg and 9.0 pg of lead, respectively. The lead concentrations in different types of flour samples were found in the range of 25-52 μg kg- 1. Finally, homogeneity factors representing the heterogeneity of analyte distribution for lead in flour samples were determined.

  7. Two new advanced forms of spectrometry for space and commercial applications

    NASA Technical Reports Server (NTRS)

    Schlager, Kenneth J.

    1991-01-01

    Reagentless ultraviolet absorption spectrometry (UVAS) and Liquid Atomic Emission Spectrometry (LAES) represent new forms of spectrometry with extensive potential in both space and commercial applications. Originally developed under KSC sponsorship for monitoring nutrient solutions for the Controlled Ecological Life Support System (CELSS), both UVAS and LAES have extensive analytical capabilities for both organic and inorganic chemical compounds. Both forms of instrumentation involve the use of remote fiber optic probes and real-time measurements for on-line process monitoring. Commercial applications exist primarily in environmental analysis and for process control in the chemical, pulp and paper, food processing, metal plating, and water/wastewater treatment industries.

  8. Sequential injection ionic liquid dispersive liquid-liquid microextraction for thallium preconcentration and determination with flame atomic absorption spectrometry.

    PubMed

    Anthemidis, Aristidis N; Ioannou, Kallirroy-Ioanna G

    2012-08-01

    A novel, automatic on-line sequential injection dispersive liquid-liquid microextraction (SI-DLLME) method, based on 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF(6)]) ionic liquid as an extractant solvent was developed and demonstrated for trace thallium determination by flame atomic absorption spectrometry. The ionic liquid was on-line fully dispersed into the aqueous solution in a continuous flow format while the TlBr(4)(-) complex was easily migrated into the fine droplets of the extractant due to the huge contact area of them with the aqueous phase. Furthermore, the extractant was simply retained onto the surface of polyurethane foam packed into a microcolumn. No specific conditions like low temperature are required for extractant isolation. All analytical parameters of the proposed method were investigated and optimized. For 15 mL of sample solution, an enhancement factor of 290, a detection limit of 0.86 μg L(-1) and a precision (RSD) of 2.7% at 20.0 μg L(-1) Tl(I) concentration level, was obtained. The developed method was evaluated by analyzing certified reference materials while good recoveries from environmental and biological samples proved that present method was competitive in practical applications.

  9. Determination of ultra-trace aluminum in human albumin by cloud point extraction and graphite furnace atomic absorption spectrometry.

    PubMed

    Sun, Mei; Wu, Qianghua

    2010-04-15

    A cloud point extraction (CPE) method for the preconcentration of ultra-trace aluminum in human albumin prior to its determination by graphite furnace atomic absorption spectrometry (GFAAS) had been developed in this paper. The CPE method was based on the complex of Al(III) with 1-(2-pyridylazo)-2-naphthol (PAN) and Triton X-114 was used as non-ionic surfactant. The main factors affecting cloud point extraction efficiency, such as pH of solution, concentration and kind of complexing agent, concentration of non-ionic surfactant, equilibration temperature and time, were investigated in detail. An enrichment factor of 34.8 was obtained for the preconcentration of Al(III) with 10 mL solution. Under the optimal conditions, the detection limit of Al(III) was 0.06 ng mL(-1). The relative standard deviation (n=7) of sample was 3.6%, values of recovery of aluminum were changed from 92.3% to 94.7% for three samples. This method is simple, accurate, sensitive and can be applied to the determination of ultra-trace aluminum in human albumin. 2009 Elsevier B.V. All rights reserved.

  10. In-situ suspended aggregate microextraction of gold nanoparticles from water samples and determination by electrothermal atomic absorption spectrometry.

    PubMed

    Choleva, Tatiana G; Kappi, Foteini A; Tsogas, George Z; Vlessidis, Athanasios G; Giokas, Dimosthenis L

    2016-05-01

    This work describes a new method for the extraction and determination of gold nanoparticles in environmental samples by means of in-situ suspended aggregate microextraction and electrothermal atomic absorption spectrometry. The method relies on the in-situ formation of a supramolecular aggregate phase through ion-association between a cationic surfactant and a benzene sulfonic acid derivative. Gold nanoparticles are physically entrapped into the aggregate phase which is separated from the bulk aqueous solution by vacuum filtration on the surface of a cellulose filter in the form of a thin film. The film is removed from the filter surface and is dissociated into an acidified methanolic solution which is used for analysis. Under the optimized experimental conditions, gold nanoparticles can be efficiently extracted from water samples with recovery rates between 81.0-93.3%, precision 5.4-12.0% and detection limits as low as 75femtomolL(-1) using only 20mL of sample volume. The satisfactory analytical features of the method along with the simplicity indicate the efficiency of this new approach to adequately collect and extract gold nanoparticle species from water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Determination of trace nickel in hydrogenated cottonseed oil by electrothermal atomic absorption spectrometry after microwave-assisted digestion.

    PubMed

    Zhang, Gai

    2012-01-01

    Microwave digestion of hydrogenated cottonseed oil prior to trace nickel determination by electrothermal atomic absorption spectrometry (ETAAS) is proposed here for the first time. Currently, the methods outlined in U.S. Pharmacopeia 28 (USP28) or British Pharmacopeia (BP2003) are recommended as the official methods for analyzing nickel in hydrogenated cottonseed oil. With these methods the samples may be pre-treated by a silica or a platinum crucible. However, the samples were easily tarnished during sample pretreatment when using a silica crucible. In contrast, when using a platinum crucible, hydrogenated cottonseed oil acting as a reducing material may react with the platinum and destroy the crucible. The proposed microwave-assisted digestion avoided tarnishing of sample in the process of sample pretreatment and also reduced the cycle of analysis. The programs of microwave digestion and the parameters of ETAAS were optimized. The accuracy of the proposed method was investigated by analyzing real samples. The results were compared with the ones by pressurized-PTFE-bomb acid digestion and ones obtained by the U.S. Pharmacopeia 28 (USP28) method. The new method involves a relatively rapid matrix destruction technique compared with other present methods for the quantification of metals in oil. © 2011 Institute of Food Technologists®

  12. Species selective preconcentration and quantification of gold nanoparticles using cloud point extraction and electrothermal atomic absorption spectrometry.

    PubMed

    Hartmann, Georg; Schuster, Michael

    2013-01-25

    The determination of metallic nanoparticles in environmental samples requires sample pretreatment that ideally combines pre-concentration and species selectivity. With cloud point extraction (CPE) using the surfactant Triton X-114 we present a simple and cost effective separation technique that meets both criteria. Effective separation of ionic gold species and Au nanoparticles (Au-NPs) is achieved by using sodium thiosulphate as a complexing agent. The extraction efficiency for Au-NP ranged from 1.01 ± 0.06 (particle size 2 nm) to 0.52 ± 0.16 (particle size 150 nm). An enrichment factor of 80 and a low limit of detection of 5 ng L(-1) is achieved using electrothermal atomic absorption spectrometry (ET-AAS) for quantification. TEM measurements showed that the particle size is not affected by the CPE process. Natural organic matter (NOM) is tolerated up to a concentration of 10 mg L(-1). The precision of the method expressed as the standard deviation of 12 replicates at an Au-NP concentration of 100 ng L(-1) is 9.5%. A relation between particle concentration and the extraction efficiency was not observed. Spiking experiments showed a recovery higher than 91% for environmental water samples. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. A new concept of efficient therapeutic drug monitoring using the high-resolution continuum source absorption spectrometry and the surface enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Xing, Yanlong; Fuss, Harald; Lademann, Jürgen; Huang, Mao Dong; Becker-Ross, Helmut; Florek, Stefan; Patzelt, Alexa; Meinke, Martina C.; Jung, Sora; Esser, Norbert

    2018-04-01

    In this study, a new therapeutic drug monitoring approach has been tested based on the combination of CaF molecular absorption using high-resolution continuum source absorption spectrometry (HR-CSAS) and surface enhanced Raman spectroscopy (SERS). HR-CSAS with mini graphite tube was successfully tested for clinical therapeutic drug monitoring of the fluorine-containing drug capecitabine in sweat samples of cancer patients: It showed advantageous features of high selectivity (no interference from Cl), high sensitivity (characteristic mass of 0.1 ng at CaF 583.069 nm), low sample consumption (down to 30 nL) and fast measurement (no sample pretreatment and less than 1 min of responding time) in tracing the fluorine signal out of capecitabine. However, this technique has the disadvantage of the total loss of the drug's structure information after burning the sample at very high temperature. Therefore, a new concept of combining HR-CSAS with a non-destructive spectroscopic method (SERS) was proposed for the sensitive sensing and specific identification of capecitabine. We tested and succeed in obtaining the molecular characteristics of the metabolite of capecitabine (named 5-fluorouracil) by the non-destructive SERS technique. With the results shown in this work, it is demonstrated that the combined spectroscopic technique of HR-CSAS and SERS will be very useful in efficient therapeutic drug monitoring in the future.

  14. Human Vitamin B12 Absorption and Metabolism are Measured by Accelerator Mass Spectrometry Using Specifically Labeled 14C-Cobalamin

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Carkeet, C; Dueker, S R; Lango, J

    2006-01-26

    There is need for an improved test of human ability to assimilate dietary vitamin B{sub 12}. Assaying and understanding absorption and uptake of B{sub 12} is important because defects can lead to hematological and neurological complications. Accelerator mass spectrometry (AMS) is uniquely suited for assessing absorption and kinetics of {sup 14}C-labeled substances after oral ingestion because it is more sensitive than decay counting and can measure levels of carbon-14 ({sup 14}C) in microliter volumes of biological samples, with negligible exposure of subjects to radioactivity. The test we describe employs amounts of B{sub 12} in the range of normal dietary intake.more » The B{sub 12} used was quantitatively labeled with {sup 14}C at one particular atom of the DMB moiety by exploiting idiosyncrasies of Salmonellametabolism. In order to grow aerobically on ethanolamine, S. entericamust be provided with either pre-formed B{sub 12} or two of its precursors: cobinamide and dimethylbenzimidazole (DMB). When provided with {sup 14}C-DMB specifically labeled in the C2 position, cells produced {sup 14}C-B{sub 12} of high specific activity (2.1 GBq/mmol, 58 mCi/mmol) and no detectable dilution of label from endogenous DMB synthesis. In a human kinetic study, a physiological dose (1.5 mg, 2.2 KBq/59 nCi) of purified {sup 14}C-B{sub 12} was administered and showed plasma appearance and clearance curves consistent with the predicted behavior of the pure vitamin. This method opens new avenues for study of B{sub 12} assimilation.« less

  15. Phytosterol glycosides reduce cholesterol absorption in humans

    PubMed Central

    Lin, Xiaobo; Ma, Lina; Racette, Susan B.; Anderson Spearie, Catherine L.; Ostlund, Richard E.

    2009-01-01

    Dietary phytosterols inhibit intestinal cholesterol absorption and regulate whole body cholesterol excretion and balance. However, they are biochemically heterogeneous and a portion is glycosylated in some foods with unknown effects on biological activity. We tested the hypothesis that phytosterol glycosides reduce cholesterol absorption in humans. Phytosterol glycosides were extracted and purified from soy lecithin in a novel two-step process. Cholesterol absorption was measured in a series of three single-meal tests given at intervals of 2 wk to each of 11 healthy subjects. In a randomized crossover design, participants received ∼300 mg of added phytosterols in the form of phytosterol glycosides or phytosterol esters, or placebo in a test breakfast also containing 30 mg cholesterol-d7. Cholesterol absorption was estimated by mass spectrometry of plasma cholesterol-d7 enrichment 4–5 days after each test. Compared with the placebo test, phytosterol glycosides reduced cholesterol absorption by 37.6 ± 4.8% (P < 0.0001) and phytosterol esters 30.6 ± 3.9% (P = 0.0001). These results suggest that natural phytosterol glycosides purified from lecithin are bioactive in humans and should be included in methods of phytosterol analysis and tables of food phytosterol content. PMID:19246636

  16. Direct determination of Pb in raw milk by graphite furnace atomic absorption spectrometry (GF AAS) with electrothermal atomization sampling from slurries.

    PubMed

    de Oliveira, Tatiane Milão; Augusto Peres, Jayme; Lurdes Felsner, Maria; Cristiane Justi, Karin

    2017-08-15

    Milk is an important food in the human diet due to its physico-chemical composition; therefore, it is necessary to monitor contamination by toxic metals such as Pb. Milk sample slurries were prepared using Triton X-100 and nitric acid for direct analysis of Pb using graphite furnace atomic absorption spectrometry - GF AAS. After dilution of the slurries, 10.00µl were directly introduced into the pyrolytic graphite tube without use of a chemical modifier, which acts as an advantage considering this type of matrix. The limits of detection and quantification were 0.64 and 2.14µgl -1 , respectively. The figures of merit studied showed that the proposed methodology without pretreatment of the raw milk sample and using external standard calibration is suitable. The methodology was applied in milk samples from the Guarapuava region, in Paraná State (Brazil) and Pb concentrations ranged from 2.12 to 37.36µgl -1 . Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Bicarbonate absorption stimulates active calcium absorption in the rat proximal tubule.

    PubMed Central

    Bomsztyk, K; Calalb, M B

    1988-01-01

    To evaluate the effect of luminal bicarbonate on calcium reabsorption, rat proximal tubules were perfused in vivo. Perfusion solution contained mannitol to reduce water flux to zero. Total Ca concentration was measured by atomic absorption spectrometry, Ca ion concentration in the tubule lumen (CaL2+) and the peritubular capillary (CaP2+), and luminal pH (pHL) with ion-selective microelectrodes and transepithelial voltage (VTE) with conventional microelectrodes. When tubules were perfused with buffer-free Cl-containing solution, net Ca absorption (JCa) averaged 3.33 pmol/min. Even though VTE was 1.64 mV lumen-positive, CaL2+, 1.05 mM, did not fall below the concentration in the capillary blood, 1.07 mM. When 27 mM of Cl was replaced with HCO3, there was luminal fluid acidification. Despite a decrease in VTE and CaL2+, JCa increased to 7.13 pmol/min, indicating that the enhanced JCa could not be accounted for by the reduced electrochemical gradient, delta CCa. When acetazolamide or an analogue of amiloride was added to the HCO3 solution, JCa was not different from the buffer-free solution, suggesting that HCO3-stimulated JCa may be linked to acidification. To further test this hypothesis, we used 27 mM Hepes as the luminal buffer. With Hepes there was luminal fluid acidification and JCa was not different from the buffer-free solution but delta CCa was significantly reduced, indicating enhanced active calcium transport. We conclude from the results of the present study that HCO3 stimulates active Ca absorption, a process that may be linked to acidification-mediated HCO3 absorption. PMID:3366902

  18. Simultaneous determination of Cd and Fe in beans and soil of different regions of Brazil using high-resolution continuum source graphite furnace atomic absorption spectrometry and direct solid sampling.

    PubMed

    dos Santos, Lisia M G; Welz, Bernhard; Araujo, Rennan G O; Jacob, Silvana do C; Vale, Maria Goreti R; Martens, Andreas; Gonzaga Martens, Irland B; Becker-Ross, Helmut

    2009-11-11

    A fast routine screening method for the simultaneous determination of cadmium and iron in bean and soil samples is proposed, using high-resolution continuum source graphite furnace atomic absorption spectrometry and direct solid sampling. The primary absorption line at 228.802 nm has been used for the determination of cadmium, and an adjacent secondary line, at 228.726 nm, for iron. Fourteen bean samples and 10 soil samples from nine states all over Brazil have been analyzed. The limits of detection (3 sigma, n = 10) were 2.0 microg kg(-1) for Cd and 4.5 mg kg(-1) for Fe. The relative standard deviation ranged from 4 to 7% for Cd and from 5 to 28% for Fe, which is usually acceptable for a screening method. The accuracy of the method has been confirmed by the analysis of two certified reference materials; the results were in agreement with the certified values at a 95% confidence interval.

  19. Water dynamics of Ser-His-Glu-Cys-Asn powder and effects of moisture absorption on its chemical properties.

    PubMed

    Lin, Songyi; Xue, Peiyu; Yang, Shuailing; Li, Xingfang; Dong, Xiuping; Chen, Feng

    2017-08-01

    This study has elucidated moisture dynamics in the soybean peptide, Ser-His-Glu-Cys-Asn (SHECN) powder by using dynamic vapor sorption (DVS) and nuclear magnetic resonance (NMR). We also tried to investigate the effects of moisture absorption on the biological activity and chemical properties of SHECN with some effective methods such as mid-infrared (MIR) spectroscopy and gas chromatography-mass spectrometry (GC-MS). DVS results showed that the moisture absorption of SHECN could reach a maximum of 33%, and the SHECN powder after synthesis actually existed in a trihydrate state of SHECN.3H 2 O. Low-field NMR revealed that three water proportions including strong combined water, binding water and bulk water were involved in SHECN moisture absorption and absored water dominantly existed in the form of combined water. Magnetic resonance imaging (MRI) and MIR spectroscopy results indicated that moisture absorption could change the morphology and structure of SHECN. After moisture absorption at 50% and 75% relative humidity, 19 volatiles were identified by GC-MS analysis. Additionally, this study showed that a part of reductive groups in SHECN was oxidized and its antioxidant ability declined significantly (P < 0.05) after moisture absorption. Water absorbed into SHECN powder can significantly change its microstructure and cause its activity to decrease. We must prevent SHECN from absorbing moisture during storage because the water can accelerate the oxidation of samples and promote microbial reactions. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  20. Flow injection for the determination of Se(IV) and Se(VI) by hydride generation atomic absorption spectrometry with microwave oven on-line prereduction of Se(VI) to Se(IV)

    NASA Astrophysics Data System (ADS)

    Burguera, J. L.; Carrero, P.; Burguera, M.; Rondon, C.; Brunetto, M. R.; Gallignani, M.

    1996-12-01

    An on-line flow injection system has been developed for the selective determination of Se(IV) and Se(VI) in citric fruit juices and geothermal waters by hydride generation atomic absorption spectrometry with microwave-aided heating prereduction of Se(VI) to Se(IV). The samples and the prereductant solutions (4 mol l -1 HCl for Se(IV) and 12 mol l -1 HCl for Se(VI)) which circulated in a closed-flow circuit were injected by means of a time-based injector. This mixture was displaced by a carrier solution of 1% v/v of hydrochloric acid through a PTFE coil located inside the focused microwave oven and mixed downstream with a borohydride solution to generate the hydride. The linear ranges were 0-120 and 0-100 μg l -1 of Se(IV) and Se(VI), respectively. The detection limits were 1.0 μg l -1 for Se(IV) and 1.5 μg l -1 for Se(VI). The precision (about 2.0-2.5% RSD) and recoveries (96-98% for Se(IV) and 94-98% for Se(VI)) were good. Total selenium values were also obtained by electrothermal atomic absorption spectrometry which agreed with the content of both selenium species. The sample throughput was about 50 measurements per hour. The main advantage of the method is that the selective determination of Se(IV) and Se(VI) in citric fruit juices and geothermal waters is performed in a closed system with a minimum sample manipulation, exposure to the environment, minimum sample waste and operator attention.

  1. Speciation of Mn(II), Mn(VII) and total manganese in water and food samples by coprecipitation-atomic absorption spectrometry combination.

    PubMed

    Citak, Demirhan; Tuzen, Mustafa; Soylak, Mustafa

    2010-01-15

    A speciation procedure based on the coprecipitation of manganese(II) with zirconium(IV) hydroxide has been developed for the investigation of levels of manganese species. The determination of manganese levels was performed by flame atomic absorption spectrometry (FAAS). Total manganese was determined after the reduction of Mn(VII) to Mn(II) by ascorbic acid. The analytical parameters including pH, amount of zirconium(IV), sample volume, etc., were investigated for the quantitative recoveries of manganese(II). The effects of matrix ions were also examined. The recoveries for manganese(II) were in the range of 95-98%. Preconcentration factor was calculated as 50. The detection limit for the analyte ions based on 3 sigma (n=21) was 0.75 microg L(-1) for Mn(II). The relative standard deviation was found to be lower than 7%. The validation of the presented procedure was performed by analysis of certified reference material having different matrices, NIST SRM 1515 (Apple Leaves) and NIST SRM 1568a (Rice Flour). The procedure was successfully applied to natural waters and food samples.

  2. Differential optical absorption spectrometer for measurement of tropospheric pollutants

    NASA Astrophysics Data System (ADS)

    Evangelisti, F.; Baroncelli, A.; Bonasoni, P.; Giovanelli, G.; Ravegnani, F.

    1995-05-01

    Our institute has recently developed a differential optical absorption spectrometry system called the gas analyzer spectrometer correlating optical absorption differences (GASCOAD), which features as a detector a linear image sensor that uses an artificial light source for long-path tropospheric-pollution monitoring. The GASCOAD, its method of eliminating interference from background sky light, and subsequent spectral analysis are reported and discussed. The spectrometer was used from 7 to 22 February 1993 in Milan, a heavily polluted metropolitan area, to measure the concentrations of SO2, NO2, O3, and HNO2 averaged over a 1.7-km horizontal light path. The findings are reported and briefly discussed.

  3. Data Processing Algorithm for Diagnostics of Combustion Using Diode Laser Absorption Spectrometry.

    PubMed

    Mironenko, Vladimir R; Kuritsyn, Yuril A; Liger, Vladimir V; Bolshov, Mikhail A

    2018-02-01

    A new algorithm for the evaluation of the integral line intensity for inferring the correct value for the temperature of a hot zone in the diagnostic of combustion by absorption spectroscopy with diode lasers is proposed. The algorithm is based not on the fitting of the baseline (BL) but on the expansion of the experimental and simulated spectra in a series of orthogonal polynomials, subtracting of the first three components of the expansion from both the experimental and simulated spectra, and fitting the spectra thus modified. The algorithm is tested in the numerical experiment by the simulation of the absorption spectra using a spectroscopic database, the addition of white noise, and the parabolic BL. Such constructed absorption spectra are treated as experimental in further calculations. The theoretical absorption spectra were simulated with the parameters (temperature, total pressure, concentration of water vapor) close to the parameters used for simulation of the experimental data. Then, spectra were expanded in the series of orthogonal polynomials and first components were subtracted from both spectra. The value of the correct integral line intensities and hence the correct temperature evaluation were obtained by fitting of the thus modified experimental and simulated spectra. The dependence of the mean and standard deviation of the evaluation of the integral line intensity on the linewidth and the number of subtracted components (first two or three) were examined. The proposed algorithm provides a correct estimation of temperature with standard deviation better than 60 K (for T = 1000 K) for the line half-width up to 0.6 cm -1 . The proposed algorithm allows for obtaining the parameters of a hot zone without the fitting of usually unknown BL.

  4. Determination and Quantification of metals in the shells of Crassostrea virginica after the Deepwater Horizon oil spill utilizing Atomic Absorption Spectrometry.

    NASA Astrophysics Data System (ADS)

    Roopnarine, D.; Patel, S.; Roopnarine, P.; Giarikos, D.; Anderson, L. C.

    2017-12-01

    The Deepwater Horizon (DWH) oil rig explosion on April 20, 2010 resulted in the release of 685,000 tons of crude oil into the Gulf of Mexico (GOM) over a period of three months. There were obvious immediate effects, but the long-term ramifications are still being studied. The primary constituent of crude oil is hydrocarbons with other organic compounds containing nitrogen, oxygen and sulfur. There are also a number of trace metals with the most abundant frequently being iron, nickel, copper and vanadium. These do not degrade like organic materials. However, the exact composition varies among the production sites. The oil from the DWH rig was classified as light crude which is moderately volatile. Natural oil seeps occur in the environment, but the DWH spill represented an acute impact. Trace amounts of heavy metals are a normal part of the composition of marine organisms, but can be toxic in high concentrations. Bivalved molluscs bioaccumulate heavy metals in their tissues and shells, and are therefore often useful as monitors of environmental pollution. We thus used the Eastern oyster Crassostrea virginica to determine the impact of the spill by measuring the concentrations of metals in the shells utilizing flame emission atomic absorption spectrometry. We focused on the hypothesis that DWH spill exposure resulted in an increase in metal uptake into the shells. Specimens spanned the years 2010 to 2014 and ranged from Grand Isle, LA to Apalachicola Bay, Fl. Vanadium had the greatest concentration in the shells, and along with copper, cadmium, zinc and iron displayed an upward trend of increase from 2010 to 2013, with a decline in 2014. However there was unexpected variability, as the specimens from Apalachicola Bay, Fl had higher levels of vanadium when compared to those from Grand Isle, LA. Ongoing work includes an increase of sample sizes from the same geographic localities and time period.

  5. Overtone Mobility Spectrometry (Part 2): Theoretical Considerations of Resolving Power

    PubMed Central

    Valentine, Stephen J.; Stokes, Sarah T.; Kurulugama, Ruwan T.; Nachtigall, Fabiane M.; Clemmer, David E.

    2009-01-01

    The transport of ions through multiple drift regions is modeled in order to develop an equation that is useful for an understanding of the resolving power of an overtone mobility spectrometry (OMS) technique. It is found that resolving power is influenced by a number of experimental variables, including those that define ion mobility spectrometry (IMS) resolving power: drift field (E), drift region length (L), and buffer gas temperature (T). However, unlike IMS, the resolving power of OMS is also influenced by the number of drift regions (n), harmonic frequency value (m), and the phase number (ϕ) of the applied drift field. The OMS resolving power dependence upon the new OMS variables (n, m, and ϕ) scales differently than the square root dependence of the E, L, and T variables in IMS. The results provide insight about optimal instrumental design and operation. PMID:19230705

  6. Coupled high performance liquid chromatography-microwave digestion-hydride generation-atomic absorption spectrometry for inorganic and organic arsenic speciation in fish tissue.

    PubMed

    Villa-Lojo, M C; Alonso-Rodríguez, E; López-Mahía, P; Muniategui-Lorenzo, S; Prada-Rodríguez, D

    2002-06-10

    A high performance liquid chromatography-microwave digestion-hydride generation-atomic absorption spectrometry (HPLC-MW-HG-AAS) coupled method is described for As(III), As(V), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenobetaine (AsB) and arsenocholine (AsC) determination. A Hamilton PRP-X100 anion-exchange column is used for carrying out the arsenic species separation. As mobile phase 17 mM phosphate buffer (pH 6.0) is used for As(III), As(V), MMA and DMA separation, and ultrapure water (pH 6.0) for AsB and AsC separation. Prior to injection into the HPLC system AsB and AsC are isolated from the other arsenic species using a Waters Accell Plus QMA cartridge. A microwave digestion with K(2)S(2)O(8) as oxidizing agent is used for enhancing the efficiency of conversion of AsB and AsC into arsenate. Detection limits achieved were between 0.3 and 1.1 ng for all species. The method was applied to arsenic speciation in fish samples.

  7. Solid-phase extraction and separation procedure for trace aluminum in water samples and its determination by high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS).

    PubMed

    Ciftci, Harun; Er, Cigdem

    2013-03-01

    In the present study, a separation/preconcentration procedure for determination of aluminum in water samples has been developed by using a new atomic absorption spectrometer concept with a high-intensity xenon short-arc lamp as continuum radiation source, a high-resolution double-echelle monochromator, and a charge-coupled device array detector. Sample solution pH, sample volume, flow rate of sample solution, volume, and concentration of eluent for solid-phase extraction of Al chelates with 4-[(dicyanomethyl)diazenyl] benzoic acid on polymeric resin (Duolite XAD-761) have been investigated. The adsorbed aluminum on resin was eluted with 5 mL of 2 mol L(-1) HNO(3) and its concentration was determined by high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS). Under the optimal conditions, limit of detection obtained with HR-CS FAAS and Line Source FAAS (LS-FAAS) were 0.49 μg L(-1) and 3.91 μg L(-1), respectively. The accuracy of the procedure was confirmed by analyzing certified materials (NIST SRM 1643e, Trace elements in water) and spiked real samples. The developed procedure was successfully applied to water samples.

  8. Nonlinear absorption of short intense laser pulse in multispecies plasma

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kargarian, A.; Hajisharifi, K.; Mehdian, H.

    In the present paper, the detailed investigation concerning the effect of inclusion of heavy negative ions into the finite background plasma on the laser absorption has been carried out by employing particle-in-cell simulation method. For this purpose, in this configuration, the laser energy absorption relying on the nonlinear phenomena such as phase-mixing, wave-breaking, and scattering has been studied in the Raman-Brillouin regime. It is shown that the inclusion of heavy negative ions suppresses the scattering while increases the phase-mixing time. Moreover, it is illustrated that this inclusion can increase the laser absorption in finite plasma environment, after saturation. The obtainedmore » results are expected to be relevant to the experiments on the mass spectrometry with laser desorption techniques as well as on the laser-plasma interaction with application to particles acceleration.« less

  9. Etalon Array Reconstructive Spectrometry

    NASA Astrophysics Data System (ADS)

    Huang, Eric; Ma, Qian; Liu, Zhaowei

    2017-01-01

    Compact spectrometers are crucial in areas where size and weight may need to be minimized. These types of spectrometers often contain no moving parts, which makes for an instrument that can be highly durable. With the recent proliferation in low-cost and high-resolution cameras, camera-based spectrometry methods have the potential to make portable spectrometers small, ubiquitous, and cheap. Here, we demonstrate a novel method for compact spectrometry that uses an array of etalons to perform spectral encoding, and uses a reconstruction algorithm to recover the incident spectrum. This spectrometer has the unique capability for both high resolution and a large working bandwidth without sacrificing sensitivity, and we anticipate that its simplicity makes it an excellent candidate whenever a compact, robust, and flexible spectrometry solution is needed.

  10. Investigating the variability in brown carbon light-absorption properties

    NASA Astrophysics Data System (ADS)

    Saleh, R.; Cheng, Z.; Atwi, K.

    2017-12-01

    Combustion of biomass fuels contributes a significant portion of brown carbon (BrC), the light-absorbing fraction of organic aerosols. BrC exhibits highly variable light-absorption properties, with imaginary part of the refractive indices (k) reported in the literature varying over two orders of magnitude. This high variability in k is attributed to the chaotic nature of combustion; however, there is a major gap in the fundamental understanding of this variability. To address this gap, we hypothesize that BrC is comprised of black carbon (BC) precursors whose transformation to BC has not seen fruition. Depending on the combustion conditions, these BC precursors exhibit different maturity levels which dictate their light-absorption properties (k). The more mature are the precursors, the more absorptive (or BC-like) they are. Therefore, k of BrC obtained from a certain measurement depends on the specific combustion conditions associated with the measurement, leading to the aforementioned variability in the literature. To test this hypothesis, we performed controlled combustion experiments in which the combustion conditions (temperature and air/fuel ratio) were varied and k was retrieved from real-time multi-wavelength light-absorption measurements at each condition. We used benzene, the inception of which during combustion is the initial critical step leading to BC formation, as a model fuel. By varying the combustion conditions from relatively inefficient (low temperature and/or air/fuel ratio) to relatively efficient (high temperature and/or air/fuel ratio), we isolated BrC components with progressively increasing k, spanning the wide range reported in the literature. We also performed thermodenuder measurements to constrain the volatility of the BrC, as well as laser desorption ionization mass spectrometry analysis to constrain its molecular mass. We found that as the combustion conditions approached the BC-formation threshold, the increase in k was associated

  11. Mercury(II) and methyl mercury determinations in water and fish samples by using solid phase extraction and cold vapour atomic absorption spectrometry combination.

    PubMed

    Tuzen, Mustafa; Karaman, Isa; Citak, Demirhan; Soylak, Mustafa

    2009-07-01

    A method has been developed for mercury(II) and methyl mercury speciation on Staphylococcus aureus loaded Dowex Optipore V-493 micro-column in the presented work, by using cold vapour atomic absorption spectrometry. Selective and sequential elution with 0.1 molL(-1) HCl for methyl mercury and 2 molL(-1) HCl for mercury(II) were performed at the pH range of 2-6. Optimal analytical conditions including pH, amounts of biosorbent, sample volumes were investigated. The detection limits of the analytes were 2.5 ngL(-1) for Hg(II) and 1.7 ngL(-1) for methyl mercury. The capacity of biosorbent for mercury(II) and methyl mercury was 6.5 and 5.4 mgg(-1), respectively. The validation of the presented procedure is performed by the analysis of standard reference material. The speciation procedure established was successfully applied to the speciation of mercury(II) and methyl mercury in natural water and microwave digested fish samples.

  12. Multiwalled carbon nanotubes as a sorbent material for the solid phase extraction of lead from urine and subsequent determination by electrothermal atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Peña Crecente, Rosa M.; Lovera, Carlha Gutiérrez; García, Julia Barciela; Méndez, Jennifer Álvarez; Martín, Sagrario García; Latorre, Carlos Herrero

    2014-11-01

    The determination of lead in urine is a way of monitoring the chemical exposure to this metal. In the present paper, a new method for the Pb determination by electrothermal atomic absorption spectrometry (ETAAS) in urine at low levels has been developed. Lead was separated from the undesirable urine matrix by means of a solid phase extraction (SPE) procedure. Oxidized multiwalled carbon nanotubes have been used as a sorbent material. Lead from urine was retained at pH 4.0 and was quantitatively eluted using a 0.7 M nitric acid solution and was subsequently measured by ETAAS. The effects of parameters that influence the adsorption-elution process (such as pH, eluent volume and concentration, sampling and elution flow rates) and the atomic spectrometry conditions have been studied by means of different factorial design strategies. Under the optimized conditions, the detection and quantification limits obtained were 0.08 and 0.26 μg Pb L- 1, respectively. The results demonstrate the absence of a urine matrix effect and this is the consequence of the SPE process carried out. Therefore, the developed method is useful for the analysis of Pb at low levels in real samples without the influence of other urine components. The proposed method was applied to the determination of lead in urine samples of unexposed healthy people and satisfactory results were obtained (in the range 3.64-22.9 μg Pb L- 1).

  13. [Determination of trace cobalt in human urine by graphite furnace atomic absorption spectrometr].

    PubMed

    Zhong, L X; Ding, B M; Jiang, D; Liu, D Y; Yu, B; Zhu, B L; Ding, L

    2016-05-20

    To establish a method to determine cobalt in human urine by graphite furnace atomic absorption spectrometry. Urine with 2% nitric acid diluted two-fold, to quantify the curve, graphite furnace atomic absorption spectrometric detection. Co was linear within 2.5~40.0 ng/ml with r>0.999. Spike experiment showed that Co received good recovery rate, which was 90.8%~94.8%. Intra-assay precisions were 3.2%~5.1% for Co, inter-assay precisions were 4.4%~5.2% for Co. The method by using graphite furnace atomic absorption spectrometr to determine urine Co was fast, accurate and with low matrix effect. It could meet the requirement in GBZ/T 210.5-2008.

  14. Determination of inorganic arsenic and its organic metabolites in urine by flow-injection hydride generation atomic absorption spectrometry.

    PubMed

    Hanna, C P; Tyson, J F; McIntosh, S

    1993-08-01

    A method has been developed for the determination of inorganic arsenic [As(III) and As(V)] and its organic metabolites (monomethylarsenic and dimethylarsenic) in urine by flow-injection hydride generation atomic absorption spectrometry. The nontoxic seafood-derived arsenobetaine and arsenocholine species were first separated by a solid-phase extraction procedure. The remaining sample was digested with a mixture of nitric and sulfuric acids and potassium dichromate, followed by attack with hydrogen peroxide. The resulting As(V) was reduced to As(III) with potassium iodide in hydrochloric acid before injection into the flow-injection manifold. The percentage analytical recoveries (mean +/- 95% confidence interval) of various arsenic species added to a urine specimen at 250 micrograms/L were 108 +/- 2, 112 +/- 11, 104 +/- 7, and 95 +/- 5 for As(III), As(V), monomethylarsenic, and dimethylarsenic, respectively. For the determination of arsenic in Standard Reference Material 2670 (toxic metals in human urine), results agreed with the certified value (480 +/- 100 micrograms/L). Analyses of samples for the Centre de Toxicologie du Quebec, containing seafood-derived species, demonstrated the viability of the separation procedure. Detection limits were between 0.1 and 0.2 microgram/L in the solution injected into the manifold, and precision at 10 micrograms/L was between 2% and 3% (CV). These preliminary results show that the method might be applicable to determinations of arsenic in a range of clinical urine specimens.

  15. Determining the arsenic, cadmium, lead, copper and chromium contents by atomic absorption spectrometry in Pangasius fillets from Vietnam.

    PubMed

    Molognoni, Luciano; Vitali, Luciano; Ploêncio, Leandro As; Santos, Jacson N; Daguer, Heitor

    2016-07-01

    Pangasius is a fish produced on a large scale in Vietnam and exported to many countries. Since river contamination from human activities can affect the safety of this food, fish consumption can cause exposure to potentially toxic elements for humans. The aim of this study, therefore, was to assess arsenic, cadmium, lead, copper and chromium contents by atomic absorption spectrometry in Pangasius fillet produced in the provinces of Dong Thap and Can Tho (Vietnam) and exported to Brazil. The limits of detection were: arsenic 0.5443 µg kg(-1) , cadmium 0.0040 mg kg(-1) , chromium 0.0004 mg kg(-1) , copper 0.0037 mg kg(-1) and lead 0.0284 mg kg(-1) . Analysis of 20 samples showed results below the limit of detection for arsenic, chromium and lead, while copper average concentration was 0.0234 mg kg(-1) . Cadmium average concentration was 0.0547 mg kg(-1) , with no significant difference between the two regions studied. The samples of Pangasius had no detectable concentrations of arsenic, chromium, copper and lead, and do not represent a hazard to public health. However, cadmium analysis revealed non-compliant samples, demonstrating the importance of monitoring the quality of imported Pangasius fish. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  16. Validation of a hydride generation atomic absorption spectrometry methodology for determination of mercury in fish designed for application in the Brazilian national residue control plan.

    PubMed

    Damin, Isabel C F; Santo, Maria A E; Hennigen, Rosmari; Vargas, Denise M

    2013-01-01

    In the present study, a method for the determination of mercury (Hg) in fish was validated according to ISO/IEC 17025, INMETRO (Brazil), and more recent European recommendations (Commission Decision 2007/333/EC and 2002/657/EC) for implementation in the Brazilian Residue Control Plan (NRCP) in routine applications. The parameters evaluated in the validation were investigated in detail. The results obtained for limit of detection and quantification were respectively, 2.36 and 7.88 μg kg(-1) of Hg. While the recovery varies between 90-96%. The coefficient of variation was of 4.06-8.94% for the repeatability. Furthermore, a comparison using an external proficiency testing scheme was realized. The results of method validated for the determination of the mercury in fish by Hydride generation atomic absorption spectrometry were considered suitable for implementation in routine analysis.

  17. Quantitative determination of flavonoids by column high-performance liquid chromatography with mass spectrometry and ultraviolet absorption detection in Artemisia afra and comparative studies with various species of Artemisia plants.

    PubMed

    Avula, Bharathi; Wang, Yan-Hong; Smillie, Troy J; Mabusela, Wilfred; Vincent, Leszek; Weitz, Frans; Khan, Ikhlas A

    2009-01-01

    A simple and specific analytical method for the quantitative determination of flavonoids from the aerial parts of the Artemisia afra plant samples was developed. By column high-performance liquid chromatography (HPLC) with UV absorption and mass spectrometry (MS) detection, separation was achieved on a reversed-phase octadecylsilyl (C18) column with water, methanol, and acetonitrile, all containing 0.1% acetic acid, as the mobile phase. These methods were used to analyze various species of Artemisia plant samples. The wavelength used for quantification of flavonoids with the diode array detector was 335 nm. The limits of detection (LOD) by HPLC/MS were found to be 7.5, 7.5, 10, 2.0, and 2.0 ng/mL; and by LC-UV the LODs were 500, 500, 500, 300, and 300 ng/mL for apigenin, chrysoeriol, tamarixetin, acacetin, and genkwanin, respectively. The HPLC/MS method was found to be 50-150 times more sensitive than the HPLC-UV method. HPLC/MS coupled with an electrospray ionization interface is described for the identification and quantification of flavonoids in various plant samples. This method involved the use of the [M+H]+ ions of the compounds at mass-to-charge ratio of 1.0606, 301.0712, 317.0661, 285.0763, and 285.0763 (calculated mass), respectively, in the positive ion mode with extractive ion monitoring.

  18. A comparison of simultaneous plasma, atomic absorption, and iron colorimetric determinations of major and trace constituents in acid mine waters

    USGS Publications Warehouse

    Ball, J.W.; Nordstrom, D. Kirk

    1994-01-01

    Sixty-three water samples collected during June to October 1982 from the Leviathan/Bryant Creek drainage basin were originally analyzed by simultaneous multielement direct-current plasma (DCP) atomic-emission spectrometry, flame atomic-absorption spectrometry, graphite-furnace atomic-absorption spectrometry (GFAAS) (thallium only), ultraviolet-visible spectrometry, and hydride-generation atomic-absorption spectrometry.Determinations were made for the following metallic and semi-metallic constituents: AI, As, B, Ba, Be, Bi, Cd, Ca, Cr, Co, Cu, Fe(11), Fe(total), Li, Pb, Mg, Mn, Mo, Ni, K, Sb, Se, Si, Na, Sr, TI, V, and Zn. These samples were re-analyzed later by simultaneous multielement inductively coupled plasma (ICP) atomic-emission spectrometry and Zeeman-corrected GFAAS to determine the concentrations of many of the same constituents with improved accuracy, precision, and sensitivity. The result of this analysis has been the generation of comparative concentration values for a significant subset of the solute constituents. Many of the more recently determined values replace less-than-detection values for the trace metals; others constitute duplicate analyses for the major constituents. The multiple determinations have yielded a more complete, accurate, and precise set of analytical data. They also have resulted in an opportunity to compare the performance of the plasma-emission instruments operated in their respective simultaneous multielement modes. Flame atomic-absorption spectrometry was judged best for Na and K and hydride-generation atomic-absorption spectrometry was judged best for As because of their lower detection limit and relative freedom from interelement spectral effects. Colorimetric determination using ferrozine as the color agent was judged most accurate, precise, and sensitive for Fe. Cadmium, lead, and vanadium concentrations were too low in this set of samples to enable a determination of whether ICP or DCP is a more suitable technique. Of

  19. Analysis of metal-laden water via portable X-ray fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Pearson, Delaina; Weindorf, David C.; Chakraborty, Somsubhra; Li, Bin; Koch, Jaco; Van Deventer, Piet; de Wet, Jandre; Kusi, Nana Yaw

    2018-06-01

    A rapid method for in-situ elemental composition analysis of metal-laden water would be indispensable for studying polluted water. Current analytical lab methods to determine water quality include flame atomic absorption spectrometry (FAAS), atomic absorption spectrophotometry (AAS), electrothermal atomic absorption spectrometry (EAAS), and inductively coupled plasma (ICP) spectroscopy. However only two field methods, colorimetry and absorptiometry, exist for elemental analysis of water. Portable X-ray fluorescence (PXRF) spectrometry is an effective method for elemental analysis of soil, sediment, and other matrices. However, the accuracy of PXRF is known to be affected while scanning moisture-laden soil samples. This study sought to statistically establish PXRF's predictive ability for various elements in water at different concentrations relative to inductively coupled plasma atomic emission spectroscopy (ICP-AES). A total of 390 metal-laden water samples collected from leaching columns of mine tailings in South Africa were analyzed via PXRF and ICP-AES. The PXRF showed differential effectiveness in elemental quantification. For the collected water samples, the best relationships between ICP and PXRF elemental data were obtained for K and Cu (R2 = 0.92). However, when scanning ICP calibration solutions with elements in isolation, PXRF results indicated near perfect agreement; Ca, K, Fe, Cu and Pb produced an R2 of 0.99 while Zn and Mn produced an R2 of 1.00. The utilization of multiple PXRF (stacked) beams produced stronger correlation to ICP relative to the use of a single beam in isolation. The results of this study demonstrated the PXRF's ability to satisfactorily predict the composition of metal-laden water as reported by ICP for several elements. Additionally this study indicated the need for a "Water Mode" calibration for the PXRF and demonstrates the potential of PXRF for future study of polluted or contaminated waters.

  20. Determination of Hg(II) in waters by on-line preconcentration using Cyanex 923 as a sorbent — Cold vapor atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Duan, Taicheng; Song, Xuejie; Xu, Jingwei; Guo, Pengran; Chen, Hangting; Li, Hongfei

    2006-09-01

    Using a solid phase extraction mini-column home-made from a neutral extractant Cyanex 923, inorganic Hg could be on-line preconcentrated and simultaneously separated from methyl mercury. The preconcentrated Hg (II) was then eluted with 10% HNO 3 and subsequently reduced by NaBH 4 to form Hg vapor before determination by cold vapor atomic absorption spectrometry (CVAAS). Optimal conditions for and interferences on the Hg preconcentration and measurement were at 1% HCl, for a 25 mL sample uptake volume and a 10 mL min - 1 sample loading rate. The detection limit was 0.2 ng L - 1 and much lower than that of conventional method (around 15.8 ng L - 1 ). The relative standard deviation (RSD) is 1.8% for measurements of 40 ng L - 1 of Hg and the linear working curve is from 20 to 2000 ng L - 1 (with a correlation coefficient of 0.9996). The method was applied in determination of inorganic Hg in city lake and deep well water (from Changchun, Jilin, China), and recovery test results for both samples were satisfactory.

  1. Direct extraction of lead (II) from untreated human blood serum using restricted access carbon nanotubes and its determination by atomic absorption spectrometry.

    PubMed

    Barbosa, Valéria Maria Pereira; Barbosa, Adriano Francisco; Bettini, Jefferson; Luccas, Pedro Orival; Figueiredo, Eduardo Costa

    2016-01-15

    Oxidized carbon nanotubes were covered with layers of bovine serum albumin to result in so-called restricted-access carbon nanotubes (RACNTs). This material can extract Pb(2+) ions directly from untreated human blood serum while excluding all the serum proteins. The RACNTs have a protein exclusion capacity of almost 100% and a maximum Pb(2+) adsorption capacity of 34.5mg g(-1). High resolution transmission electron microscopy, scanning transmission electron microscopy and energy dispersive spectroscopy were used to confirm the BSA layer and Pb(2+) adsorption sites. A mini-column filled with RACNTs was used in an on-line solid phase extraction system coupled to a thermospray flame furnace atomic absorption spectrometry. At optimized experimental conditions, the method has a detection limit as low as 2.1µg L(-1), an enrichment factor of 5.5, and inter- and intra-day precisions (expressed as relative standard deviation) of <8.1%. Recoveries of the Pb(2+) spiked samples ranged from 89.4% to 107.3% for the extraction from untreated human blood serum. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Accuracy of a method based on atomic absorption spectrometry to determine inorganic arsenic in food: Outcome of the collaborative trial IMEP-41.

    PubMed

    Fiamegkos, I; Cordeiro, F; Robouch, P; Vélez, D; Devesa, V; Raber, G; Sloth, J J; Rasmussen, R R; Llorente-Mirandes, T; Lopez-Sanchez, J F; Rubio, R; Cubadda, F; D'Amato, M; Feldmann, J; Raab, A; Emteborg, H; de la Calle, M B

    2016-12-15

    A collaborative trial was conducted to determine the performance characteristics of an analytical method for the quantification of inorganic arsenic (iAs) in food. The method is based on (i) solubilisation of the protein matrix with concentrated hydrochloric acid to denature proteins and allow the release of all arsenic species into solution, and (ii) subsequent extraction of the inorganic arsenic present in the acid medium using chloroform followed by back-extraction to acidic medium. The final detection and quantification is done by flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS). The seven test items used in this exercise were reference materials covering a broad range of matrices: mussels, cabbage, seaweed (hijiki), fish protein, rice, wheat, mushrooms, with concentrations ranging from 0.074 to 7.55mgkg(-1). The relative standard deviation for repeatability (RSDr) ranged from 4.1 to 10.3%, while the relative standard deviation for reproducibility (RSDR) ranged from 6.1 to 22.8%. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  3. A new cloud point extraction procedure for determination of inorganic antimony species in beverages and biological samples by flame atomic absorption spectrometry.

    PubMed

    Altunay, Nail; Gürkan, Ramazan

    2015-05-15

    A new cloud-point extraction (CPE) for the determination of antimony species in biological and beverages samples has been established with flame atomic absorption spectrometry (FAAS). The method is based on the fact that formation of the competitive ion-pairing complex of Sb(III) and Sb(V) with Victoria Pure Blue BO (VPB(+)) at pH 10. The antimony species were individually detected by FAAS. Under the optimized conditions, the calibration range for Sb(V) is 1-250 μg L(-1) with a detection limit of 0.25 μg L(-1) and sensitive enhancement factor of 76.3 while the calibration range for Sb(III) is 10-400 μg L(-1) with a detection limit of 5.15 μg L(-1) and sensitive enhancement factor of 48.3. The precision as a relative standard deviation is in range of 0.24-2.35%. The method was successfully applied to the speciative determination of antimony species in the samples. The validation was verified by analysis of certified reference materials (CRMs). Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Impurity profiling of liothyronine sodium by means of reversed phase HPLC, high resolution mass spectrometry, on-line H/D exchange and UV/Vis absorption.

    PubMed

    Ruggenthaler, M; Grass, J; Schuh, W; Huber, C G; Reischl, R J

    2017-09-05

    For the first time, a comprehensive investigation of the impurity profile of the synthetic thyroid API (active pharmaceutical ingredient) liothyronine sodium (LT 3 Na) was performed by using reversed phase HPLC and advanced structural elucidation techniques including high resolution tandem mass spectrometry (HRMS/MS) and on-line hydrogen-deuterium (H/D) exchange. Overall, 39 compounds were characterized and 25 of these related substances were previously unknown to literature. The impurity classification system recently developed for the closely related API levothyroxine sodium (LT 4 Na) could be applied to the newly characterized liothyronine sodium impurities resulting in a wholistic thyroid API impurity classification system. Furthermore, the mass-spectrometric CID-fragmentation of specific related substances was discussed and rationalized by detailed fragmentation pathways. Moreover, the UV/Vis absorption characteristics of the API and selected impurities were investigated to corroborate chemical structure assignments derived from MS data. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. An automated flow injection system for metal determination by flame atomic absorption spectrometry involving on-line fabric disk sorptive extraction technique.

    PubMed

    Anthemidis, A; Kazantzi, V; Samanidou, V; Kabir, A; Furton, K G

    2016-08-15

    A novel flow injection-fabric disk sorptive extraction (FI-FDSE) system was developed for automated determination of trace metals. The platform was based on a minicolumn packed with sol-gel coated fabric media in the form of disks, incorporated into an on-line solid-phase extraction system, coupled with flame atomic absorption spectrometry (FAAS). This configuration provides minor backpressure, resulting in high loading flow rates and shorter analytical cycles. The potentials of this technique were demonstrated for trace lead and cadmium determination in environmental water samples. The applicability of different sol-gel coated FPSE media was investigated. The on-line formed complex of metal with ammonium pyrrolidine dithiocarbamate (APDC) was retained onto the fabric surface and methyl isobutyl ketone (MIBK) was used to elute the analytes prior to atomization. For 90s preconcentration time, enrichment factors of 140 and 38 and detection limits (3σ) of 1.8 and 0.4μgL(-1) were achieved for lead and cadmium determination, respectively, with a sampling frequency of 30h(-1). The accuracy of the proposed method was estimated by analyzing standard reference materials and spiked water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Determination of mercury in agroindustrial samples by flow-injection cold vapor atomic absorption spectrometry using ion exchange and reductive elution.

    PubMed

    Gomes Neto, J A; Zara, L F; Rocha, J C; Santos, A; Dakuzaku, C S; Nóbrega, J A

    2000-03-06

    A flow-injection system with a Chelite-S(R) cationic resin packed minicolumn is proposed for the determination of trace levels of mercury in agroindustrial samples by cold vapor atomic absorption spectrometry. Improved sensitivity and selectivity are attained since mercuric ions are on-line concentrated whereas other potential interferents are discarded. With on-line reductive elution procedure, concentrated hydrochloric acid could be replaced by 10% w/v SnCl(2), in 6 M HCl as eluent. The reversed-intermittent stream either carries the atomic mercury to the flow cell in the forward direction or removes the residue from reactor/gas-liquid separator to a discarding flask in the opposite direction. Concentration and volume of reagent, acidity, flow rates, commutation times and potential interfering species were investigated. For 120 s preconcentration time, the proposed system handles about 25 samples h(-1) (50.0-500 ng l(-1)), consuming about 10 ml sample and 5 mg SnCl(2) per determination. The detection limit is 0.8 ng l(-1) and the relative standard deviation (RSD) (n=12) of a 76.7 ng l(-1) sample is about 5%. Results are in agreement with certified value of standard materials at 95% confidence level and good recoveries (97-128%) of spiked samples were found.

  7. Remote laser evaporative molecular absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Hughes, Gary B.; Lubin, Philip; Cohen, Alexander; Madajian, Jonathan; Kulkarni, Neeraj; Zhang, Qicheng; Griswold, Janelle; Brashears, Travis

    2016-09-01

    We describe a novel method for probing bulk molecular and atomic composition of solid targets from a distant vantage. A laser is used to melt and vaporize a spot on the target. With sufficient flux, the spot temperature rises rapidly, and evaporation of surface materials occurs. The melted spot creates a high-temperature blackbody source, and ejected material creates a plume of surface materials in front of the spot. Molecular and atomic absorption occurs as the blackbody radiation passes through the ejected plume. Bulk molecular and atomic composition of the surface material is investigated by using a spectrometer to view the heated spot through the ejected plume. The proposed method is distinct from current stand-off approaches to composition analysis, such as Laser-Induced Breakdown Spectroscopy (LIBS), which atomizes and ionizes target material and observes emission spectra to determine bulk atomic composition. Initial simulations of absorption profiles with laser heating show great promise for Remote Laser-Evaporative Molecular Absorption (R-LEMA) spectroscopy. The method is well-suited for exploration of cold solar system targets—asteroids, comets, planets, moons—such as from a spacecraft orbiting the target. Spatial composition maps could be created by scanning the surface. Applying the beam to a single spot continuously produces a borehole or trench, and shallow subsurface composition profiling is possible. This paper describes system concepts for implementing the proposed method to probe the bulk molecular composition of an asteroid from an orbiting spacecraft, including laser array, photovoltaic power, heating and ablation, plume characteristics, absorption, spectrometry and data management.

  8. Ionic liquid-based extraction followed by graphite-furnace atomic absorption spectrometry for the determination of trace heavy metals in high-purity iron metal.

    PubMed

    Matsumiya, Hiroaki; Kato, Tatsuya; Hiraide, Masataka

    2014-02-01

    The analysis of high-purity materials for trace impurities is an important and challenging task. The present paper describes a facile and sensitive method for the determination of trace heavy metals in high-purity iron metal. Trace heavy metals in an iron sample solution were rapidly and selectively preconcentrated by the extraction into a tiny volume of an ionic liquid [1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide] for the determination by graphite-furnace atomic absorption spectrometry (GFAAS). A nitrogen-donating neutral ligand, 2,4,6-tris(2-pyridyl)-1,3,5-triazine (TPTZ), was found to be effective in the ionic liquid-based selective extraction, allowing the nearly complete (~99.8%) elimination of the iron matrix. The combination with the optimized GFAAS was successful. The detectability reached sub-μg g(-1) levels in iron metal. The novel use of TPTZ in ionic liquid-based extraction followed by GFAAS was successfully applied to the determination of traces of Co, Ni, Cu, Cd, and Pb in certified reference materials for high-purity iron metal. © 2013 Published by Elsevier B.V.

  9. Vortex-assisted switchable liquid-liquid microextraction for the preconcentration of cadmium in environmental samples prior to its determination with flame atomic absorption spectrometry.

    PubMed

    Fırat, Merve; Bodur, Süleyman; Tışlı, Büşra; Özlü, Cansu; Chormey, Dotse Selali; Turak, Fatma; Bakırdere, Sezgin

    2018-06-12

    In this study, a switchable solvent was used to preconcentrate trace amounts of Cd from aqueous solution for its determination by flame atomic absorption spectrometry (FAAS). Protonation of N,N-dimethylbenzylamine by dry ice (solid CO 2 ) made it water soluble, and addition of sodium hydroxide converted it back to its original nonionic state for phase separation and subsequent extraction of Cd. A slotted quartz tube (SQT) was attached to the flame burner head to increase the residence time of Cd atoms in the light path. Under the optimum conditions, limits of detection and quantification were determined as 0.7 and 2.6 μg L -1 , respectively. Low relative standard deviations calculated from seven replicate measurements of the lowest concentration indicated high precision. Accuracy of the developed method was checked by using a standard reference material (SRM 1633c). Spiked recovery tests were also performed on lake water and wastewater samples at different concentrations to check the applicability of the developed method, and the results obtained (90-103%) established high recovery.

  10. Measurements of atmospheric ethene by solar absorption FTIR spectrometry

    NASA Astrophysics Data System (ADS)

    Toon, Geoffrey C.; Blavier, Jean-Francois L.; Sung, Keeyoon

    2018-04-01

    Atmospheric ethene (C2H4; ethylene) amounts have been retrieved from high-resolution solar absorption spectra measured by the Jet Propulsion Laboratory (JPL) MkIV interferometer. Data recorded from 1985 to 2016 from a dozen ground-based sites have been analyzed, mostly between 30 and 67° N. At clean-air sites such as Alaska, Sweden, New Mexico, or the mountains of California, the ethene columns were always less than 1 × 1015 molec cm-2 and therefore undetectable. In urban sites such as JPL, California, ethene was measurable with column amounts of 20 × 1015 molec cm-2 observed in the 1990s. Despite the increasing population and traffic in southern California, a factor 3 decrease in ethene column density is observed over JPL over the past 25 years, accompanied by a decrease in CO. This is likely due to southern California's increasingly stringent vehicle exhaust regulations and tighter enforcement over this period.

  11. Surface tuning laser desorption/ionization mass spectrometry (STLDI-MS) for the analysis of small molecules using quantum dots.

    PubMed

    Abdelhamid, Hani Nasser; Chen, Zhen-Yu; Wu, Hui-Fen

    2017-08-01

    In most applications of quantum dots (QDs) for surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS), one side of QDs is supported by a solid substrate (stainless - steel plate), whereas the other side is in contact with the target analytes. Therefore, the surface capping agent of QDs is a key parameter for laser desorption/ionization mass spectrometry (LDI-MS). Cadmium telluride quantum dots (CdTe QDs) modified with different capping agents are synthesized, characterized, and applied for surface tuning laser desorption/ionization mass spectrometry (STLDI-MS). Data shows that CdTe quantum dot modified cysteine (cys@CdTe QDs) has an absorption that matches with the wavelength of the N 2 laser (337 nm). The synergistic effect of large surface area and absorption of the laser irradiation of cys@CdTe QDs enhances the LDI-MS process for small - molecule analysis, including α-, β-, and γ-cyclodextrin, gramicidin D, perylene, pyrene, and triphenylphosphine. Cys@CdTe QDs are also applied using Al foils as substrates. Aluminum foil combined with cys@CdTe QDs enhances the ionization efficiency and is cheap compared to traditional matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) with a stainless - steel plate.

  12. Determination of arsenic and cadmium in crude oil by direct sampling graphite furnace atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    de Jesus, Alexandre; Zmozinski, Ariane Vanessa; Damin, Isabel Cristina Ferreira; Silva, Márcia Messias; Vale, Maria Goreti Rodrigues

    2012-05-01

    In this work, a direct sampling graphite furnace atomic absorption spectrometry method has been developed for the determination of arsenic and cadmium in crude oil samples. The samples were weighed directly on the solid sampling platforms and introduced into the graphite tube for analysis. The chemical modifier used for both analytes was a mixture of 0.1% Pd + 0.06% Mg + 0.06% Triton X-100. Pyrolysis and atomization curves were obtained for both analytes using standards and samples. Calibration curves with aqueous standards could be used for both analytes. The limits of detection obtained were 5.1 μg kg- 1 for arsenic and 0.2 μg kg- 1 for cadmium, calculated for the maximum amount of sample that can be analyzed (8 mg and 10 mg) for arsenic and cadmium, respectively. Relative standard deviations lower than 20% were obtained. For validation purposes, a calibration curve was constructed with the SRM 1634c and aqueous standards for arsenic and the results obtained for several crude oil samples were in agreement according to paired t-test. The result obtained for the determination of arsenic in the SRM against aqueous standards was also in agreement with the certificate value. As there is no crude oil or similar reference material available with a certified value for cadmium, a digestion in an open vessel under reflux using a "cold finger" was adopted for validation purposes. The use of paired t-test showed that the results obtained by direct sampling and digestion were in agreement at a 95% confidence level. Recovery tests were carried out with inorganic and organic standards and the results were between 88% and 109%. The proposed method is simple, fast and reliable, being appropriated for routine analysis.

  13. Determination of cadmium and lead in table salt by sequential multi-element flame atomic absorption spectrometry.

    PubMed

    Amorim, Fábio A C; Ferreira, Sérgio L C

    2005-02-28

    In the present paper, a simultaneous pre-concentration procedure for the sequential determination of cadmium and lead in table salt samples using flame atomic absorption spectrometry is proposed. This method is based on the liquid-liquid extraction of cadmium(II) and lead(II) ions as dithizone complexes and direct aspiration of the organic phase for the spectrometer. The sequential determination of cadmium and lead is possible using a computer program. The optimization step was performed by a two-level fractional factorial design involving the variables: pH, dithizone mass, shaking time after addition of dithizone and shaking time after addition of solvent. In the studied levels these variables are not significant. The experimental conditions established propose a sample volume of 250mL and the extraction process using 4.0mL of methyl isobutyl ketone. This way, the procedure allows determination of cadmium and lead in table salt samples with a pre-concentration factor higher than 80, and detection limits of 0.3ngg(-1) for cadmium and 4.2ngg(-1) for lead. The precision expressed as relative standard deviation (n = 10) were 5.6 and 2.6% for cadmium concentration of 2 and 20ngg(-1), respectively, and of 3.2 and 1.1% for lead concentration of 20 and 200ngg(-1), respectively. Recoveries of cadmium and lead in several samples, measured by standard addition technique, proved also that this procedure is not affected by the matrix and can be applied satisfactorily for the determination of cadmium and lead in saline samples. The method was applied for the evaluation of the concentration of cadmium and lead in table salt samples consumed in Salvador City, Bahia, Brazil.

  14. Ion Mobility Spectrometry-Hydrogen Deuterium Exchange Mass Spectrometry of Anions: Part 1. Peptides to Proteins

    NASA Astrophysics Data System (ADS)

    Donohoe, Gregory C.; Khakinejad, Mahdiar; Valentine, Stephen J.

    2015-04-01

    Ion mobility spectrometry (IMS) coupled with hydrogen deuterium exchange (HDX)-mass spectrometry (MS) has been used to study the conformations of negatively-charged peptide and protein ions. Results are presented for ion conformers of angiotensin 1, a synthetic peptide (SP), bovine insulin, ubiquitin, and equine cytochrome c. In general, the SP ion conformers demonstrate a greater level of HDX efficiency as a greater proportion of the sites undergo HDX. Additionally, these ions exhibit the fastest rates of exchange. Comparatively, the angiotensin 1 ions exhibit a lower rate of exchange and HDX level presumably because of decreased accessibility of exchange sites by charge sites. The latter are likely confined to the peptide termini. Insulin ions show dramatically reduced HDX levels and exchange rates, which can be attributed to decreased conformational flexibility resulting from the disulfide bonds. For the larger ubiquitin and protein ions, increased HDX is observed for larger ions of higher charge state. For ubiquitin, a conformational transition from compact to more elongated species (from lower to higher charge states) is reflected by an increase in HDX levels. These results can be explained by a combination of interior site protection by compact conformers as well as decreased access by charge sites. The elongated cytochrome c ions provide the largest HDX levels where higher values correlate with charge state. These results are consistent with increased exchange site accessibility by additional charge sites. The data from these enhanced IMS-HDX experiments are described in terms of charge site location, conformer rigidity, and interior site protection.

  15. Determination of free and total sulfur(IV) compounds in coconut water using high-resolution continuum source molecular absorption spectrometry in gas phase.

    PubMed

    Oliveira, Michael L; Brandao, Geovani C; de Andrade, Jailson B; Ferreira, Sergio L C

    2018-03-01

    This work proposes a method for the determination of free and total sulfur(IV) compounds in coconut water samples, using the high-resolution continuum source molecular absorption spectrometry. It is based on the measurement of the absorbance signal of the SO 2 gas generate, which is resultant of the addition of hydrochloric acid solution on the sample containing the sulfating agent. The sulfite bound to the organic compounds is released by the addition of sodium hydroxide solution, before the generation of the SO 2 gas. The optimization step was performed using multivariate methodology involving volume, concentration and flow rate of hydrochloric acid. This method was established by the sum of the absorbances obtained in the three lines of molecular absorption of the SO 2 gas. This strategy allowed a procedure for the determination of sulfite with limits of detection and quantification of 0.36 and 1.21mgL -1 (for a sample volume of 10mL) and precision expressed as relative standard deviation of 5.4% and 6.4% for a coconut water sample containing 38.13 and 54.58mgL -1 of free and total sulfite, respectively. The method was applied for analyzing five coconut water samples from Salvador city, Brazil. The average contents varied from 13.0 to 55.4mgL -1 for free sulfite and from 24.7 to 66.9mgL -1 for total sulfur(IV) compounds. The samples were also analyzed employing the Ripper´s procedure, which is a reference method for the quantification of this additive. A statistical test at 95% confidence level demonstrated that there is no significant difference between the results obtained by the two methods. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Aerosol Angstrom Absorption Coefficient Comparisons during MILAGRO.

    NASA Astrophysics Data System (ADS)

    Marley, N. A.; Marchany-Rivera, A.; Kelley, K. L.; Mangu, A.; Gaffney, J. S.

    2007-12-01

    Measurements of aerosol absorption were obtained as part of the MAX-Mex component of the MILAGRO field campaign at site T0 (Instituto Mexicano de Petroleo in Mexico City) by using a 7-channel aethalometer (Thermo- Anderson) during the month of March, 2006. The absorption measurements obtained in the field at 370, 470, 520, 590, 660, 880, and 950 nm were used to determine the aerosol Angstrom absorption exponents by linear regression. Since, unlike other absorbing aerosol species (e.g. humic like substances, nitrated PAHs), black carbon absorption is relatively constant from the ultraviolet to the infrared with an Angstrom absorption exponent of -1 (1), a comparison of the Angstrom exponents can indicate the presence of aerosol components with an enhanced UV absorption over that expected from BC content alone. The Angstrom exponents determined from the aerosol absorption measurements obtained in the field varied from - 0.7 to - 1.3 during the study and was generally lower in the afternoon than the morning hours, indicating an increase in secondary aerosol formation and photochemically generated UV absorbing species in the afternoon. Twelve-hour integrated samples of fine atmospheric aerosols (<0.1micron) were also collected at site T0 and T1 (Universidad Technologica de Tecamac, State of Mexico) from 5 am to 5 pm (day) and from 5 pm to 5 am (night) during the month of March 2006. Samples were collected on quartz fiber filters with high volume impactor samplers. Continuous absorption spectra of these aerosol samples have been obtained in the laboratory from 280 to 900nm with the use of an integrating sphere coupled to a UV spectrometer (Beckman DU with a Labsphere accessory). The integrating sphere allows the detector to collect and spatially integrate the total radiant flux reflected from the sample and therefore allows for the measurement of absorption on highly reflective or diffusely scattering samples. These continuous spectra have also been used to obtain the

  17. A dispersive liquid--liquid microextraction methodology for copper (II) in environmental samples prior to determination using microsample injection flame atomic absorption spectrometry.

    PubMed

    Alothman, Zeid A; Habila, Mohamed; Yilmaz, Erkan; Soylak, Mustafa

    2013-01-01

    A simple, environmentally friendly, and efficient dispersive liquid-liquid microextraction method combined with microsample injection flame atomic absorption spectrometry was developed for the separation and preconcentration of Cu(II). 2-(5-Bromo-2-pyridylazo)-5-(diethylamino)phenol (5-Br-PADAP) was used to form a hydrophobic complex of Cu(II) ions in the aqueous phase before extraction. To extract the Cu(II)-5-Br-PADAP complex from the aqueous phase to the organic phase, 2.0 mL of acetone as a disperser solvent and 200 microL of chloroform as an extraction solvent were used. The influences of important analytical parameters, such as the pH, types and volumes of the extraction and disperser solvents, amount of chelating agent, sample volume, and matrix effects, on the microextraction procedure were evaluated and optimized. Using the optimal conditions, the LOD, LOQ, preconcentration factor, and RSD were determined to be 1.4 microg/L, 4.7 microg/L, 120, and 6.5%, respectively. The accuracy of the proposed method was investigated using standard addition/recovery tests. The analysis of certified reference materials produced satisfactory analytical results. The developed method was applied for the determination of Cu in real samples.

  18. Solid sampling high-resolution continuum source graphite furnace atomic absorption spectrometry for gold determination in geological samples after preconcentration onto carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Dobrowolski, Ryszard; Mróz, Agnieszka; Dąbrowska, Marzena; Olszański, Piotr

    2017-06-01

    A novelty method for the determination of gold in geological samples by solid sampling high-resolution continuum source graphite furnace atomic absorption spectrometry (SS HR CS GF AAS) after solid-phase extraction onto modified carbon nanotubes (CNT) was described. The methodology developed is based on solid phase extraction of Au(III) ions from digested samples to eliminate strong interference caused by iron compounds and problems related to inhomogeneities of the samples. The use of aqueous or solid standard for calibration was studied and the slope of calibration curve was the same for both of these modes. This statement indicates the possibility to perform the calibration of the method using aqueous standard solutions. Under optimum conditions the absolute detection limit for gold was equal to 2.24 · 10- 6 μg g- 1 while the adsorption capacity of modified carbon nanotubes was 264 mg g- 1. The proposed procedure was validated by the application of certified reference materials (CRMs) with different content of gold and different matrix, the results were in good agreement with certified values. The method was successfully applied for separation and determination of gold ions in complex geological samples, with precision generally better than 8%.

  19. Ultrasound-Assisted Emulsification Microextraction Based on Solidification Floating Organic Drop Trace Amounts of Manganese Prior to Graphite Furnace Atomic Absorption Spectrometry Determination

    PubMed Central

    Mohadesi, Alireza; Falahnejad, Masoumeh

    2012-01-01

    In the present study, an ultrasound-assisted emulsification microextraction based on solidification floating organic drop method is described for preconcentration of trace amounts of Mn (II). 2-(5-Bromo-2-pyridylazo)-5 diethylaminophenol was added to a solution of Mn+2 at ph = 10.0. After this, 1-undecanol was added to the solution as an extraction solvent, and solution was stirred. Several factors influencing the microextraction efficiency, such as pH, the amount of chelating agent, nature and volume of extraction solvent, the volume of sample solution, stirring rate, and extraction time were investigated and optimized. Then sample vial was cooled by inserting into an ice bath, and the solidified was transferred into a suitable vial for immediate melting. Finally the sample was injected into a graphite furnace atomic absorption spectrometry. Under the optimum condition the linear dynamic range was 0.50–10.0 ng mL−1 with a correlation coefficient of 0.9926, and the detection limit of 0.3 ng mL−1 was obtained. The enrichment factor was 160. The proposed method was successfully applied for separation and determination of manganese in sea, rain, tap, and river water samples. PMID:22645504

  20. Absorption dynamics and delay time in complex potentials

    NASA Astrophysics Data System (ADS)

    Villavicencio, Jorge; Romo, Roberto; Hernández-Maldonado, Alberto

    2018-05-01

    The dynamics of absorption is analyzed by using an exactly solvable model that deals with an analytical solution to Schrödinger’s equation for cutoff initial plane waves incident on a complex absorbing potential. A dynamical absorption coefficient which allows us to explore the dynamical loss of particles from the transient to the stationary regime is derived. We find that the absorption process is characterized by the emission of a series of damped periodic pulses in time domain, associated with damped Rabi-type oscillations with a characteristic frequency, ω = (E + ε)/ℏ, where E is the energy of the incident waves and ‑ε is energy of the quasidiscrete state of the system induced by the absorptive part of the Hamiltonian; the width γ of this resonance governs the amplitude of the pulses. The resemblance of the time-dependent absorption coefficient with a real decay process is discussed, in particular the transition from exponential to nonexponential regimes, a well-known feature of quantum decay. We have also analyzed the effect of the absorptive part of the potential on the dynamical delay time, which behaves differently from the one observed in attractive real delta potentials, exhibiting two regimes: time advance and time delay.

  1. Application of l-cystine modified zeolite for preconcentration and determination of ultra-trace levels of cadmium by flame atomic absorption spectrometry.

    PubMed

    Rezvani, Seyyed Ahmad; Soleymanpour, Ahmad

    2016-03-04

    A very convenient, sensitive and precise solid phase extraction (SPE) system was developed for enrichment and determination of ultra-trace of cadmium ion in water and plant samples. This method was based on the retention of cadmium(II) ions by l-cystine adsorbed in Y-zeolite and carry out in a packed mini-column. The retained cadmium ions then were eluted and determined by flame atomic absorption spectrometry. The scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and Fourier Transform Infrared (FT-IR) spectroscopy techniques were applied for the characterization of cystine modified zeolite (CMZ). Some experimental conditions affecting the analytical performance such as pH, eluent type, concentration of sample, eluent flow rate and also the presence of interfering ions were investigated. The calibration graph was linear within the range of 0.1-7.5ngmL(-1) and limit of detection was obtained 0.04ngmL(-1) with the preconcentration factor of 400. The relative standard deviation (RSD) was obtained 1.4%, indicating the excellent reproducibility of this method. The proposed method was successfully applied for the extraction and determination of cadmium(II) ion in black tea, cigarette's tobacco and also various water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Use of slurry sampling for the direct determination of zinc in yogurt by high resolution-continuum source flame atomic absorption spectrometry.

    PubMed

    Brandao, Geovani C; de Jesus, Raildo M; da Silva, Erik G P; Ferreira, Sergio L C

    2010-06-15

    This paper presents an analytical procedure for the direct determination of zinc in yogurt employing sampling slurry and high resolution-continuum source flame atomic absorption spectrometry (HR-CS FAAS). The step optimization established the experimental conditions of: 2.0molL(-1) hydrochloric acid, a sonication time of 20min and a sample mass of 1.0g for a slurry volume of 25mL. This method allows the determination of zinc with a limit of quantification of 0.32microgg(-1). The precision expressed as relative standard deviation (RSD) were 0.82 and 2.08% for yogurt samples containing zinc concentrations of 4.85 and 2.49microgg(-1), respectively. The accuracy was confirmed by the analysis of a certified reference material of non-fat milk powder furnished by the National Institute of Standard and Technology. The proposed method was applied for the determination of zinc in seven yogurt samples. The zinc content was varied from 2.19 to 4.85microgg(-1). These results agreed with those reported in the literature. The samples were also analyzed after acid digestion and zinc determination by FAAS. No statistical difference was observed between the results obtained by both of the procedures performed.

  3. Determination of sulfur in kerosene by combustion and molecular absorption spectrometry in the gas phase

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ruschak, M.L.; Syty, A.

    1982-08-01

    A technique of nonflame molecular adsorption in the gas phase developed for the determination of sulfite trapped in tetrachloromercurate, is described herein for application to the determination of total sulfur in kerosene. The burner head is removed from the atomic absorption spectrometer and replaced with a flow-through absorption cell. A special reaction vessel is used to evolve SO/sub 2/ from the sulfite in a precise and convenient manner. The transient absorbance caused by the SO/sub 2/, as it is carried through the absorption cell, is measured. Both spiked and unspiked samples of kerosene were analyzed, and the reproducibility of themore » repeated runs is evidenced by a relative standard deviation from the mean of 5% for the unspiked kerosene and 4% for the spiked kerosene. If the detection level is defined as that concentration of S which gives a % S twice the standard deviation from the mean yields, the detection limit for the present method is 0.002% S by weight in kerosene.« less

  4. Synthesize of silver-nanoparticles by plant extract and its application for preconcentration of cadmium followed by flame atomic absorption spectrometry.

    PubMed

    Almertaha, Abdul-Hossein; Eftekhari, Mohammad; Chamsaz, Mahmoud; Gheibi, Mohammad

    2018-02-02

    In this paper, Mentha pulegium leaves extract was used as a green reducing agent for the synthesis of silver-nanoparticles. The synthesized silver-nanoparticles were characterized by UV-VIS spectrophotometry, transmission electron microscopy, X-ray spectroscopy and used as an adsorbent for preconcentration of trace levels of cadmium (ІІ). After the desorption of cadmium (ІІ) in 5 mol L -1 formic acid, the desorbent solution was aspirated into the flame atomic absorption spectrometry for the determination of cadmium. In order to optimize the experimental condition, a response surface methodology based on central composite design was used. The optimum conditions are: pH: 8.6, amounts of adsorbent: 30 mg, 10 min extraction time and desorption time of 2 min. Under the optimum condition, the calibration curve was linear in the range of 5-200 μg L -1 cadmium (ІІ) ion with a correlation coefficient of 0.9995. The limit of detection was 1.1 μg L -1 and the relative standard deviation for 25 μg L -1 cadmium (ІІ) ion was 3.0% (n = 5). In order to check the applicability of the proposed method, different real samples were analyzed. Also, the accuracy of this method was successfully checked by the analysis of certified reference material and spike tests.

  5. Evaluation of ammonia as diluent for serum sample preparation and determination of selenium by graphite furnace atomic absorption spectrometry*1

    NASA Astrophysics Data System (ADS)

    Hernández-Caraballo, Edwin A.; Burguera, Marcela; Burguera, José L.

    2002-12-01

    A method for the determination of total selenium in serum samples by graphite furnace atomic absorption spectrometry was evaluated. The method involved direct introduction of 1:5 diluted serum samples (1% v/v NH 4OH+0.05% w/v Triton X-100 ®) into transversely heated graphite tubes, and the use of 10 μg Pd+3 μg Mg(NO 3) 2 as chemical modifier. Optimization of the modifier mass and the atomization temperature was conducted by simultaneously varying such parameters and evaluating both the integrated absorbance and the peak height/peak area ratio. The latter allowed the selection of compromise conditions rendering good sensitivity and adequate analyte peak profiles. A characteristic mass of 49 pg and a detection limit (3s) of 6 μg 1 -1 Se, corresponding to 30 μg l -1 Se in the serum sample, were obtained. The analyte addition technique was used for calibration. The accuracy was assessed by the determination of total selenium in Seronorm™ Trace Elements Serum Batch 116 (Nycomed Pharma AS). The method was applied for the determination of total selenium in ten serum samples taken from individuals with no known physical affection. The selenium concentration ranged between 79 and 147 μg l -1, with a mean value of 114±22 μg l -1.

  6. Determination of metals in lubricating oils by flame atomic absorption spectrometry using a single-bore high-pressure pneumatic nebulizer.

    PubMed

    Mora, J; Todolí, J L; Sempere, F J; Canals, A; Hernandis, V

    2000-12-01

    The behaviour of a single-bore high-pressure pneumatic nebulizer (SBHPPN) as a tool for the analysis of lubricating oils by flame atomic absorption spectrometry (FAAS) was investigated. The effects of the sample oil content [from 10% to 100% (w/w) oil in 4-methylpentan-2-one, IBMK] and the carrier nature (IBMK and methanol) on the characteristics of the aerosols generated, on the analyte transport efficiency and on the analytical figures of merit in FAAS were studied. A pneumatic concentric nebulizer (PCN) was used for comparison. Increasing the oil content increases the viscosity of the sample. With the PCN this gives rise to coarser aerosols, making it impossible to nebulize samples with an oil content higher than 70% (w/w). Using the SBHPPN, the viscosity of the sample scarcely affects the characteristics of the primary aerosols. Hence, the SBHPPN is able, by using the appropriate carrier, to nebulize pure lubricating oils. Among the carriers tested, IBMK is the most advisable because it is fully miscible with all the oil samples. The SBHPPN provides higher sensitivities and lower limits of detection than the PCN. Compared with a method based on organic dilution, the use of the SBHPPN for the direct analysis of lubricating oils by FAAS makes it possible, in addition to increasing the analysis throughput, to detect elements at lower concentrations. Moreover, the SBHPPN provides similar results to those obtained using a previous acid digestion step.

  7. Trace mercury determination in drinking and natural water samples by room temperature ionic liquid based-preconcentration and flow injection-cold vapor atomic absorption spectrometry.

    PubMed

    Martinis, Estefanía M; Bertón, Paula; Olsina, Roberto A; Altamirano, Jorgelina C; Wuilloud, Rodolfo G

    2009-08-15

    A liquid-liquid extraction procedure (L-L) based on room temperature ionic liquid (RTIL) was developed for the preconcentration and determination of mercury in different water samples. The analyte was quantitatively extracted with 1-butyl-3-methylimidazolium hexafluorophosphate ([C(4)mim][PF(6)]) under the form of Hg-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (Hg-5-Br-PADAP) complex. A volume of 500 microl of 9.0 mol L(-1) hydrochloric acid was used to back-extract the analyte from the RTIL phase into an aqueous media prior to its analysis by flow injection-cold vapor atomic absorption spectrometry (FI-CV-AAS). A preconcentration factor of 36 was achieved upon preconcentration of 20 mL of sample. The limit of detection (LOD) obtained under the optimal conditions was 2.3ngL(-1) and the relative standard deviation (RSD) for 10 replicates at 1 microg L(-1) Hg(2+) was 2.8%, calculated with peaks height. The method was successfully applied to the determination of mercury in river, sea, mineral and tap water samples and a certified reference material (CRM).

  8. Simultaneous determination of iron, cadmium, zinc, copper, nickel, lead, and uranium in seawater by stable isotope dilution spark source mass spectrometry

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mykytiuk, A.P.; Russell, D.S.; Sturgeon, R.E.

    Trace concentrations (ng/mL) of Fe, Cd, Zn, Cu, Ni, Pb, U, and Co have been determined in seawater by stable isotope dilution spark source mass spectrometry. The seawater samples were preconcentrated on the ion exchanger Chelex-100 and the concentrate was evaporated on a graphite or silver electrode. The results are compared with those obtained by graphite furnace atomic absorption spectrometry and inductively coupled plasma emission spectrometry. The technique avoids the use of calibration standards and is capable of producing results in cases where the analyte is only partially recovered. 2 tables.

  9. Gunshot residue testing in suicides: Part II: Analysis by inductive coupled plasma-atomic emission spectrometry.

    PubMed

    Molina, D Kimberley; Castorena, Joe L; Martinez, Michael; Garcia, James; DiMaio, Vincent J M

    2007-09-01

    Several different methods can be employed to test for gunshot residue (GSR) on a decedent's hands, including scanning electron microscopy with energy dispersive x-ray (SEM/EDX) and inductive coupled plasma-atomic emission spectrometry (ICP-AES). In part I of this 2-part series, GSR results performed by SEM/EDX in undisputed cases of suicidal handgun wounds were studied. In part II, the same population was studied, deceased persons with undisputed suicidal handgun wounds, but GSR testing was performed using ICP-AES. A total of 102 cases were studied and analyzed for caliber of weapon, proximity of wound, and the results of the GSR testing. This study found that 50% of cases where the deceased was known to have fired a handgun immediately prior to death had positive GSR results by ICP/AES, which did not differ from the results of GSR testing by SEM/EDX. Since only 50% of cases where the person is known to have fired a weapon were positive for GSR by either method, this test should not be relied upon to determine whether someone has discharged a firearm and is not useful as a determining factor of whether or not a wound is self-inflicted or non-self-inflicted. While a positive GSR result may be of use, a negative result is not helpful in the medical examiner setting as a negative result indicates that either a person fired a weapon prior to death or a person did not fire a weapon prior to death.

  10. Mass Spectrometry Analyses of Multicellular Tumor Spheroids.

    PubMed

    Acland, Mitchell; Mittal, Parul; Lokman, Noor A; Klingler-Hoffmann, Manuela; Oehler, Martin K; Hoffmann, Peter

    2018-05-01

    Multicellular tumor spheroids (MCTS) are a powerful biological in vitro model, which closely mimics the 3D structure of primary avascularized tumors. Mass spectrometry (MS) has established itself as a powerful analytical tool, not only to better understand and describe the complex structure of MCTS, but also to monitor their response to cancer therapeutics. The first part of this review focuses on traditional mass spectrometry approaches with an emphasis on elucidating the molecular characteristics of these structures. Then the mass spectrometry imaging (MSI) approaches used to obtain spatially defined information from MCTS is described. Finally the analysis of primary spheroids, such as those present in ovarian cancer, and the great potential that mass spectrometry analysis of these structures has for improved understanding of cancer progression and for personalized in vitro therapeutic testing is discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Determination of total arsenic and arsenic(III) in phosphate fertilizers by hydride generation atomic absorption spectrometry after ultrasound-assisted extraction based on a control acid media.

    PubMed

    Rezende, Helen Cristine; Coelho, Nivia Maria Melo

    2014-01-01

    An ultrasound-assisted extraction procedure was developed for determination of inorganic arsenic (As) in phosphate fertilizer by hydride generation atomic absorption spectrometry. The variables that affect the hydride generation step were optimized, including the reducer, acid, sample flow rate, and concentrations of the acid and reducer. The determination of As(lll) was performed through the simple control of solution pH with a 0.5 M citric acid-sodium citrate buffer solution at pH 4.5, and total As was determined after a pre-reduction reaction with 1.0% (w/v) thiourea. Ultrasound-assisted acid extraction was performed, and the parameters sonication time and acid and Triton X-114 concentrations were optimized using a 23 factorial design and central composite design. LODs for As(lll) and total As were 0.029 and 0.022 microg/L, respectively. The accuracy of the method was confirmed with certified reference materials. The method was successfully applied in the determination of inorganic As in phosphate fertilizer samples.

  12. Changes in UV absorption of sunscreens after UV irradiation

    NASA Astrophysics Data System (ADS)

    Tarras-Wahlberg, N.; Stenhagen, G.; Larkö, O.; Rosén, A.; Wennberg, A.-M.; Wennerström, O.

    2000-03-01

    In the present investigation we have studied the change in the absorption spectrum of some photoactive organic species in sunscreens after UVA and UVB irradiation in a dose normally encountered during a full day in the sun. The absorbance of 2-ethylhexyl 4-methoxycinnamate was reduced significantly, while 3-(4-methylbenzyliden)camphor seemed to be rather stable. The benzophenones studied seemed to be relatively stable. In the case of 4-tert.butyl-4´-methoxy-dibenzoylmethane there was a rapid decrease in the UVA absorption leading to unsatisfactory protection in the UVA region. 4-Isopropyl-dibenzoylmethane also lost most of its UV protective capacity after irradiation with UVA. UVB seemed to have a minor effect on all the samples. The present study including gas chromatography and mass spectrometry analysis indicates that some of the photoactive organic species commonly used today in sunscreens are unstable following UV irradiation.

  13. Dissociative absorption: An empirically unique, clinically relevant, dissociative factor.

    PubMed

    Soffer-Dudek, Nirit; Lassri, Dana; Soffer-Dudek, Nir; Shahar, Golan

    2015-11-01

    Research of dissociative absorption has raised two questions: (a) Is absorption a unique dissociative factor within a three-factor structure, or a part of one general dissociative factor? Even when three factors are found, the specificity of the absorption factor is questionable. (b) Is absorption implicated in psychopathology? Although commonly viewed as "non-clinical" dissociation, absorption was recently hypothesized to be specifically associated with obsessive-compulsive symptoms. To address these questions, we conducted exploratory and confirmatory factor analyses on 679 undergraduates. Analyses supported the three-factor model, and a "purified" absorption scale was extracted from the original inclusive absorption factor. The purified scale predicted several psychopathology scales. As hypothesized, absorption was a stronger predictor of obsessive-compulsive symptoms than of general psychopathology. In addition, absorption was the only dissociative scale that longitudinally predicted obsessive-compulsive symptoms. We conclude that absorption is a unique and clinically relevant dissociative tendency that is particularly meaningful to obsessive-compulsive symptoms. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Incorporating Biological Mass Spectrometry into Undergraduate Teaching Labs, Part 2: Peptide Identification via Molecular Mass Determination

    ERIC Educational Resources Information Center

    Arnquist, Isaac J.; Beussman, Douglas J.

    2009-01-01

    Mass spectrometry has become a routine analytical tool in the undergraduate curriculum in the form of GC-MS. While relatively few undergraduate programs have incorporated biological mass spectrometry into their programs, the importance of these techniques, as demonstrated by their recognition with the 2002 Nobel Prize, will hopefully lead to…

  15. Triple-band metamaterial absorption utilizing single rectangular hole

    NASA Astrophysics Data System (ADS)

    Kim, Seung Jik; Yoo, Young Joon; Kim, Young Ju; Lee, YoungPak

    2017-01-01

    In the general metamaterial absorber, the single absorption band is made by the single meta-pattern. Here, we introduce the triple-band metamaterial absorber only utilizing single rectangular hole. We also demonstrate the absorption mechanism of the triple absorption. The first absorption peak was caused by the fundamental magnetic resonance in the metallic part between rectangular holes. The second absorption was generated by induced tornado magnetic field. The process of realizing the second band is also presented. The third absorption was induced by the third-harmonic magnetic resonance in the metallic region between rectangular holes. In addition, the visible-range triple-band absorber was also realized by using similar but smaller single rectangular-hole structure. These results render the simple metamaterials for high frequency in large scale, which can be useful in the fabrication of metamaterials operating in the optical range.

  16. MALDI (matrix assisted laser desorption ionization) Imaging Mass Spectrometry (IMS) of skin: Aspects of sample preparation.

    PubMed

    de Macedo, Cristiana Santos; Anderson, David M; Schey, Kevin L

    2017-11-01

    MALDI (matrix assisted laser desorption ionization) Imaging Mass Spectrometry (IMS) allows molecular analysis of biological materials making possible the identification and localization of molecules in tissues, and has been applied to address many questions on skin pathophysiology, as well as on studies about drug absorption and metabolism. Sample preparation for MALDI IMS is the most important part of the workflow, comprising specimen collection and preservation, tissue embedding, cryosectioning, washing, and matrix application. These steps must be carefully optimized for specific analytes of interest (lipids, proteins, drugs, etc.), representing a challenge for skin analysis. In this review, critical parameters for MALDI IMS sample preparation of skin samples will be described. In addition, specific applications of MALDI IMS of skin samples will be presented including wound healing, neoplasia, and infection. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Overcoming Matrix Effects in a Complex Sample: Analysis of Multiple Elements in Multivitamins by Atomic Absorption Spectroscopy

    ERIC Educational Resources Information Center

    Arnold, Randy J.; Arndt, Brett; Blaser, Emilia; Blosser, Chris; Caulton, Dana; Chung, Won Sog; Fiorenza, Garrett; Heath, Wyatt; Jacobs, Alex; Kahng, Eunice; Koh, Eun; Le, Thao; Mandla, Kyle; McCory, Chelsey; Newman, Laura; Pithadia, Amit; Reckelhoff, Anna; Rheinhardt, Joseph; Skljarevski, Sonja; Stuart, Jordyn; Taylor, Cassie; Thomas, Scott; Tse, Kyle; Wall, Rachel; Warkentien, Chad

    2011-01-01

    A multivitamin tablet and liquid are analyzed for the elements calcium, magnesium, iron, zinc, copper, and manganese using atomic absorption spectrometry. Linear calibration and standard addition are used for all elements except calcium, allowing for an estimate of the matrix effects encountered for this complex sample. Sample preparation using…

  18. Copper-65-absorption by men fed intrinsically and extrinsically labeled whole wheat bread

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Johnson, P.E.; Lykken, G.I.

    Six men were fed a diet composed of conventional foods with all bread as whole wheat bread. Intrinsically labeled /sup 65/Cu bread (containing 6.5 ppm Cu and 48 atom % /sup 65/Cu) was substituted for unlabeled bread for 3 days, and stools were collected for 24 days. Extrinsically labeled bread was then substituted for 3 days and another 24-day stool collection made. /sup 65/Cu excretion was measured by mass spectrometry. Mean Cu intake was 1.10 mg of Cu/day. Average Cu balance was /minus/0.06 /+-/ 0.08 mg/day. Average absorption of the intrinsic copper was 72.2 /+-/ 9.3% and of extrinsic Cumore » 64.2 /+-/ 5.8%. The ratio of extrinsic to intrinsic absorption was 0.906 /+-/ 0.164. Absorption of intrinsic and extrinsic tracers did not differ significantly (p > 0.05) by a paired t-test, and the ratio (E/I) was not significantly different from 1. Use of extrinsic Cu tracers to assess Cu absorption is supported by these results.« less

  19. Part 2: Forensic attribution profiling of Russian VX in food using liquid chromatography-mass spectrometry.

    PubMed

    Jansson, Daniel; Lindström, Susanne Wiklund; Norlin, Rikard; Hok, Saphon; Valdez, Carlos A; Williams, Audrey M; Alcaraz, Armando; Nilsson, Calle; Åstot, Crister

    2018-08-15

    This work is part two of a three-part series in this issue of a Sweden-United States collaborative effort towards the understanding of the chemical attribution signatures of Russian VX (VR) in synthesized samples and complex food matrices. In this study, we describe the sourcing of VR present in food based on chemical analysis of attribution signatures by liquid chromatography-tandem mass spectrometry (LC-MS/MS) combined with multivariate data analysis. Analytical data was acquired from seven different foods spiked with VR batches that were synthesized via six different routes in two separate laboratories. The synthesis products were spiked at a lethal dose into seven food matrices: water, orange juice, apple purée, baby food, pea purée, liquid eggs and hot dog. After acetonitrile sample extraction, the samples were analyzed by LC-MS/MS operated in MRM mode. A multivariate statistical calibration model was built on the chemical attribution profiles from 118 VR spiked food samples. Using the model, an external test-set of the six synthesis routes employed for VR production was correctly identified with no observable major impact of the food matrices to the classification. The overall performance of the statistical models was found to be exceptional (94%) for the test set samples retrospectively classified to their synthesis routes. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. A simple heat-pipe cell for X-ray absorption spectrometry of potassium vapor

    NASA Astrophysics Data System (ADS)

    Pres̆eren, R.; Kodre, A.; Arc̆on, I.; Padez̆nik Gomils̆ek, J.; Hribar, M.

    1999-01-01

    The construction and operation of a simple high-temperature X-ray absorption cell for potassium vapor is described. The principle of "spectroscopic heat pipe" is exploited to separate kapton windows, indispensable for good transmission in the low-energy region, from the hot and aggressive vapor. High-resolution spectrum of the K-edge region of atomic potassium reveals fingerprints of multielectron photoexcitations.

  1. Green Preconcentration of Trace Amounts of Copper from Water and Food Samples onto Novel Organo-Nanoclay Prior to Flame Atomic Absorption Spectrometry.

    PubMed

    Beyki, Mostafa Hossein; Shemirani, Farzaneh; Khani, Rouhollah

    2014-01-01

    In this work, the nanoclay was intercalated with acyclovir (9-[(2-hydroxyethoxy) methyl] guanine), the toxicity of which to mammalian cells is very low. We used no organic solvents for preparation of modified clay and desorption of Cu ions from the sorbent. Batch and column methods were used, and sorption of Cu was quantitative (>98%) in the pH range of 7.5 to 10.0. Quantitative desorption occurred with 5.0 mL of 3.0 M HCl, and the amount of Cu(II) was measured by using flame atomic absorption spectrometry. In the initial solution the linear dynamic range and the LOD were 3.0-1000.0 and 0.58 μg/L, respectively. With 500.0 mL of sample, an enrichment factor of 100 was obtained. The RSD was 2.0% (n = 8, concentration = 0.5 mg/L), and the maximum capacity of the sorbent was 45.0 mg/g. The influence of experimental parameters including sample pH, ionic strength, type and volume of the eluent, and interference of some ions on the recoveries of Cu was investigated. The proposed method using a new and easier prepared solid sorbent was applied to the determination of Cu in different real samples with satisfactory results.

  2. Analysis of soils - Part II: Determination of oligosaccharides in soils by MALDI-time-of-flight mass spectrometry

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schuerch, S.; Howald, M.; Schlunegger, U.P.

    1995-12-31

    Polysaccharides are the most abundant organic compounds in nature. Decomposition of plant and animal residues leads to a high polysaccharide content in soils. The decomposition of carbohydrates and subsequent mineralization of the products are part of the cycle of life on earth. In extracts of soils collected in the Valle Onsernone (Ticino, Switzerland), oligosaccharides of different size and structure have been identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The selected soils show identical climatic parameters and pedological factors, whereas the age of fallow land is the only varying factor. Identification and structure elucidation of the oligosaccharides is performedmore » by substrate-specific enzymatic hydrolysis. Moreover the appearance and the distribution of the oligosaccharides is correlated to soil genesis.« less

  3. A model predicting the evolution of ice particle size spectra and radiative properties of cirrus clouds. Part 2: Dependence of absorption and extinction on ice crystal morphology

    NASA Technical Reports Server (NTRS)

    Mitchell, David L.; Arnott, W. Patrick

    1994-01-01

    This study builds upon the microphysical modeling described in Part 1 by deriving formulations for the extinction and absorption coefficients in terms of the size distribution parameters predicted from the micro-physical model. The optical depth and single scatter albedo of a cirrus cloud can then be determined, which, along with the asymmetry parameter, are the input parameters needed by cloud radiation models. Through the use of anomalous diffraction theory, analytical expressions were developed describing the absorption and extinction coefficients and the single scatter albedo as functions of size distribution parameters, ice crystal shapes (or habits), wavelength, and refractive index. The extinction coefficient was formulated in terms of the projected area of the size distribution, while the absorption coefficient was formulated in terms of both the projected area and mass of the size distribution. These properties were formulated as explicit functions of ice crystal geometry and were not based on an 'effective radius.' Based on simulations of the second cirrus case study described in Part 1, absorption coefficients predicted in the near infrared for hexagonal columns and rosettes were up to 47% and 71% lower, respectively, than absorption coefficients predicted by using equivalent area spheres. This resulted in single scatter albedos in the near-infrared that were considerably greater than those predicted by the equivalent area sphere method. Reflectances in this region should therefore be underestimated using the equivalent area sphere approach. Cloud optical depth was found to depend on ice crystal habit. When the simulated cirrus cloud contained only bullet rosettes, the optical depth was 142% greater than when the cloud contained only hexagonal columns. This increase produced a doubling in cloud albedo. In the near-infrared (IR), the single scatter albedo also exhibited a significant dependence on ice crystal habit. More research is needed on the

  4. [Sample preparation and bioanalysis in mass spectrometry].

    PubMed

    Bourgogne, Emmanuel; Wagner, Michel

    2015-01-01

    The quantitative analysis of compounds of clinical interest of low molecular weight (<1000 Da) in biological fluids is currently in most cases performed by liquid chromatography-mass spectrometry (LC-MS). Analysis of these compounds in biological fluids (plasma, urine, saliva, hair...) is a difficult task requiring a sample preparation. Sample preparation is a crucial part of chemical/biological analysis and in a sense is considered the bottleneck of the whole analytical process. The main objectives of sample preparation are the removal of potential interferences, analyte preconcentration, and converting (if needed) the analyte into a more suitable form for detection or separation. Without chromatographic separation, endogenous compounds, co-eluted products may affect a quantitative method in mass spectrometry performance. This work focuses on three distinct parts. First, quantitative bioanalysis will be defined, different matrices and sample preparation techniques currently used in bioanalysis by mass spectrometry of/for small molecules of clinical interest in biological fluids. In a second step the goals of sample preparation will be described. Finally, in a third step, sample preparation strategies will be made either directly ("dilute and shoot") or after precipitation.

  5. Dispersive liquid-liquid microextraction based on solidification of floating organic drop for preconcentration and determination of trace amounts of copper by flame atomic absorption spectrometry.

    PubMed

    Karadaş, Cennet; Kara, Derya

    2017-04-01

    A novel, simple, rapid, sensitive, inexpensive and environmentally friendly dispersive liquid-liquid microextraction method based on the solidification of a floating organic drop (DLLME-SFO) was developed for the determination of copper by flame atomic absorption spectrometry (FAAS). N-o-Vanillidine-2-amino-p-cresol was used as a chelating ligand and 1-undecanol was selected as an extraction solvent. The main parameters affecting the performance of DLLME-SFO, such as sample pH, volume of extraction solvent, extraction time, concentration of the chelating ligand, salt effect, centrifugation time and sample volume were investigated and optimized. The effect of interfering ions on the recovery of copper was also examined. Under the optimum conditions, the detection limit (3σ) was 0.93μgL -1 for Cu using a sample volume of 20mL, yielding a preconcentration factor of 20. The proposed method was successfully applied to the determination of Cu in tap, river and seawater, rice flour and black tea samples as well as certified reference materials. Copyright © 2016. Published by Elsevier Ltd.

  6. Separation/preconcentration and determination of vanadium with dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO) and electrothermal atomic absorption spectrometry.

    PubMed

    Asadollahi, Tahereh; Dadfarnia, Shayessteh; Shabani, Ali Mohammad Haji

    2010-06-30

    A novel dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO) for separation/preconcentration of ultra trace amount of vanadium and its determination with the electrothermal atomic absorption spectrometry (ETAAS) was developed. The DLLME-SFO behavior of vanadium (V) using N-benzoyl-N-phenylhydroxylamine (BPHA) as complexing agent was systematically investigated. The factors influencing the complex formation and extraction by DLLME-SFO method were optimized. Under the optimized conditions: 100 microL, 200 microL and 25 mL of extraction solvent (1-undecanol), disperser solvent (acetone) and sample volume, respectively, an enrichment factor of 184, a detection limit (based on 3S(b)/m) of 7 ng L(-1) and a relative standard deviation of 4.6% (at 500 ng L(-1)) were obtained. The calibration graph using the preconcentration system for vanadium was linear from 20 to 1000 ng L(-1) with a correlation coefficient of 0.9996. The method was successfully applied for the determination of vanadium in water and parsley. Copyright 2010 Elsevier B.V. All rights reserved.

  7. Aerosol Absorption Measurements in MILAGRO.

    NASA Astrophysics Data System (ADS)

    Gaffney, J. S.; Marley, N. A.; Arnott, W. P.; Paredes-Miranda, L.; Barnard, J. C.

    2007-12-01

    During the month of March 2006, a number of instruments were used to determine the absorption characteristics of aerosols found in the Mexico City Megacity and nearby Valley of Mexico. These measurements were taken as part of the Department of Energy's Megacity Aerosol Experiment - Mexico City (MAX-Mex) that was carried out in collaboration with the Megacity Interactions: Local and Global Research Observations (MILAGRO) campaign. MILAGRO was a joint effort between the DOE, NSF, NASA, and Mexican agencies aimed at understanding the impacts of a megacity on the urban and regional scale. A super-site was operated at the Instituto Mexicano de Petroleo in Mexico City (designated T-0) and at the Universidad Technologica de Tecamac (designated T-1) that was located about 35 km to the north east of the T-0 site in the State of Mexico. A third site was located at a private rancho in the State of Hidalgo approximately another 35 km to the northeast (designated T-2). Aerosol absorption measurements were taken in real time using a number of instruments at the T-0 and T-1 sites. These included a seven wavelength aethalometer, a multi-angle absorption photometer (MAAP), and a photo-acoustic spectrometer. Aerosol absorption was also derived from spectral radiometers including a multi-filter rotating band spectral radiometer (MFRSR). The results clearly indicate that there is significant aerosol absorption by the aerosols in the Mexico City megacity region. The absorption can lead to single scattering albedo reduction leading to values below 0.5 under some circumstances. The absorption is also found to deviate from that expected for a "well-behaved" soot anticipated from diesel engine emissions, i.e. from a simple 1/lambda wavelength dependence for absorption. Indeed, enhanced absorption is seen in the region of 300-450 nm in many cases, particularly in the afternoon periods indicating that secondary organic aerosols are contributing to the aerosol absorption. This is likely due

  8. Development of a simple method for the determination of lead in lipstick using alkaline solubilization and graphite furnace atomic absorption spectrometry.

    PubMed

    Soares, Aline Rodrigues; Nascentes, Clésia Cristina

    2013-02-15

    A simple method was developed for determining the total lead content in lipstick samples by graphite furnace atomic absorption spectrometry (GFAAS) after treatment with tetramethylammonium hydroxide (TMAH). Multivariate optimization was used to establish the optimal conditions of sample preparation. The graphite furnace heating program was optimized through pyrolysis and atomization curves. An aliquot containing approximately 50mg of the sample was mixed with TMAH and heated in a water bath at 60°C for 60 min. Using Nb as the permanent modifier and Pd as the chemical modifier, the optimal temperatures were 900°C and 1800°C for pyrolysis and atomization, respectively. Under optimum conditions, the working range was from 1.73 to 50.0 μg L(-1), with detection and quantification limits of 0.20 and 0.34 μg g(-1), respectively. The precision was evaluated under conditions of repeatability and intermediate precision and showed standard deviations of 2.37%-4.61% and 4.93%-9.75%, respectively. The % recovery ranged from 96.2% to 109%, and no significant differences were found between the results obtained using the proposed method and the microwave decomposition method for real samples. Lead was detected in 21 tested lipstick samples; the lead content in these samples ranged from 0.27 to 4.54 μg g(-1). Copyright © 2012 Elsevier B.V. All rights reserved.

  9. An Inexpensive Optical Absorption Experiment

    NASA Astrophysics Data System (ADS)

    Greenslade, Thomas B.

    2006-09-01

    This optical absorption experiment can be put together in only a few minutes with materials found in most secondary or undergraduate stockrooms. The absorption material is the partly transparent flexible anti-static plastic material used to package solid-state devices. The detector is a hand-held photographic exposure meter of the type that was in common use before the advent of point-and-shoot cameras. A graph of the intensity of the transmitted light as a function of the number of sheets of the material is a decreasing exponential. The emphasis of the experiment is on the mathematical form.

  10. Tellurium speciation analysis using hydride generation in situ trapping electrothermal atomic absorption spectrometry and ruthenium or palladium modified graphite tubes.

    PubMed

    Yildirim, Emrah; Akay, Pınar; Arslan, Yasin; Bakirdere, Sezgin; Ataman, O Yavuz

    2012-12-15

    Speciation of tellurium can be achieved by making use of different kinetic behaviors of Te(IV) and Te(VI) upon their reaction with sodium borohydride using hydride generation. While Te(IV) can form H(2)Te, Te(VI) will not form any volatile species during the course of hydride formation and measurement by atomic absorption spectrometry. Quantitative reduction of Te(VI) was achieved through application of a microwave assisted prereduction of Te(VI) in 6.0 mol/L HCl solution. Enhanced sensitivity was achieved by in situ trapping of the generated H(2)Te species in a previously heated graphite furnace whose surface was modified using Pd or Ru. Overall efficiency for in situ trapping in pyrolytically coated graphite tube surface was found to be 15% when volatile analyte species are trapped for 60s at 300°C. LOD and LOQ values were calculated as 0.086 ng/mL and 0.29 ng/mL, respectively. Efficiency was increased to 46% and 36% when Pd and Ru surface modifiers were used, respectively. With Ru modified graphite tube 173-fold enhancement was obtained over 180 s trapping period with respect to ETAAS; the tubes could be used for 250 cycles. LOD values were 0.0064 and 0.0022 ng/mL for Pd and Ru treated ETAAS systems, respectively, for 180 s collection of 9.6 mL sample solution. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Application of high-resolution continuum source flame atomic absorption spectrometry to reveal, evaluate and overcome certain spectral effects in Pb determination of unleaded gasoline

    NASA Astrophysics Data System (ADS)

    Kowalewska, Zofia; Laskowska, Hanna; Gzylewski, Michał

    2017-06-01

    High-resolution continuum source and line source flame atomic absorption spectrometry (HR-CS FAAS and LS FAAS, respectively) were applied for Pb determination in unleaded aviation or automotive gasoline that was dissolved in methyl-isobutyl ketone. When using HR-CS FAAS, a structured background (BG) was registered in the vicinity of both the 217.001 nm and 283.306 nm Pb lines. In the first case, the BG, which could be attributed to absorption by the OH molecule, directly overlaps with the 217 nm line, but it is of relatively low intensity. For the 283 nm line, the structured BG occurs due to uncompensated absorption by OH molecules present in the flame. BG lines of relatively high intensity are situated at a large distance from the 283 nm line, which enables accurate analysis, not only when using simple variants of HR-CS FAAS but also for LS FAAS with a bandpass of 0.1 nm. The lines of the structured spectrum at 283 nm can have ;absorption; (maxima) or ;emission; (minima) character. The intensity of the OH spectra can significantly depend on the flame character and composition of the investigated organic solution. The best detection limit for the analytical procedure, which was 0.01 mg L- 1 for Pb in the investigated solution, could be achieved using HR-CS FAAS with the 283 nm Pb line, 5 pixels for the analyte line measurement and iterative background correction (IBC). In this case, least squares background correction (LSBC) is not recommended. However, LSBC (available as the ;permanent structures; option) would be recommended when using the 217 nm Pb line. In LS FAAS, an additional phenomenon related to the nature of the organic matrix (for example, isooctane or toluene) can play an important role. The effect is of continuous character and probably due to the simultaneous efficient correction of the continuous background (IBC) it is not observed in HR-CS FAAS. The fact that the effect does not depend on the flame character indicates that it is not radiation

  12. Identification of carbohydrates by matrix-free material-enhanced laser desorption/ionisation mass spectrometry.

    PubMed

    Hashir, Muhammad Ahsan; Stecher, Guenther; Bakry, Rania; Kasemsook, Saowapak; Blassnig, Bernhard; Feuerstein, Isabel; Abel, Gudrun; Popp, Michael; Bobleter, Ortwin; Bonn, Guenther K

    2007-01-01

    Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) is a sensitive mass spectrometric technique which utilises acidic materials as matrices for laser energy absorption, desorption and ionisation of analytes. These matrix materials produce background signals particularly in the low-mass range and make the detection and identification of small molecules difficult and nearly impossible. To overcome this problem this paper introduces matrix-free material-enhanced laser desorption/ionisation mass spectrometry (mf-MELDI-MS) for the screening and analysis of small molecules such as carbohydrates. For this purpose, 4,4'-azo-dianiline was immobilised on silica gel enabling the absorption of laser energy sufficient for successful desorption and ionisation of low molecular weight compounds. The particle and pore sizes, the solvent system for suspension and the sample preparation procedures have been optimised. The newly synthesised MELDI material delivered excellent spectra with regard to signal-to-noise ratio and detection sensitivity. Finally, wheat straw degradation products and Salix alba L. plant extracts were analysed proving the high performance and excellent behaviour of the introduced material. Copyright (c) 2007 John Wiley & Sons, Ltd.

  13. Sum of the Parts: Mass Spectrometry-Based Metabolomics

    PubMed Central

    Milne, Stephen B.; Mathews, Thomas P.; Myers, David S.; Ivanova, Pavlina T.; Brown, H. Alex

    2013-01-01

    Metabolomics is a rapidly growing field of research used in the identification and quantification of the small molecule metabolites within an organism, thereby providing insights into cell metabolism and bioenergetics as well as processes important in clinical medicine, such as disposition of pharmaceutical compounds. It offers comprehensive information on thousands of low molecular weight compounds (<1500 Da) that represent a wide range of pathways and intermediary metabolism. Due to its vast expansion in the last two decades mass spectrometry has become an indispensable tool in “omic” analyses. The use of different ionization techniques such as the more traditional electrospray (ESI) and matrix-assisted laser desorption (MALDI), as well as recently popular desorption electrospray ionization (DESI), has allowed the analysis of a wide range of biomolecules (e.g. peptides, proteins, lipids and sugars), and their imaging and analysis in the original sample environment in a workup free fashion. An overview of the current state of the methodology is given, as well as examples of application. PMID:23442130

  14. Absorption of 5-aminosalicylic acid from colon and rectum.

    PubMed Central

    Bondesen, S; Schou, J B; Pedersen, V; Rafiolsadat, Z; Hansen, S H; Hvidberg, E F

    1988-01-01

    In order to clarify the characteristics of absorption of 5-aminosalicylic acid (5-ASA) from the colon, a neutral solution was instilled into the right part of the colon and the rectum, respectively, in six volunteers. A laxative (bisacodyl) and liquid meals were given prior to each instillation. No significant difference could be demonstrated between the two parts of the large bowel, but the absorption was considerably restricted compared with previous results obtained from the jejunum. The results confirm in a direct manner earlier observations on 5-ASA released from sulphasalazine. PMID:3358890

  15. Absorption Spectra of Gold Nanoparticle Suspensions

    NASA Astrophysics Data System (ADS)

    Anan'eva, M. V.; Nurmukhametov, D. R.; Zverev, A. S.; Nelyubina, N. V.; Zvekov, A. A.; Russakov, D. M.; Kalenskii, A. V.; Eremenko, A. N.

    2018-02-01

    Three gold nanoparticle suspensions are obtained, and mean radii in distributions - (6.1 ± 0.2), (11.9 ± 0.3), and (17.3 ± 0.7) nm - are determined by the transmission electron microscopy method. The optical absorption spectra of suspensions are obtained and studied. Calculation of spectral dependences of the absorption index of suspensions at values of the gold complex refractive index taken from the literature showed a significant deviation of experimental and calculated data in the region of 450-800 nm. Spectral dependences of the absorption of suspensions are simulated within the framework of the Mie-Drude theory taking into account the interband absorption in the form of an additional term in the imaginary part of the dielectric permittivity of the Gaussian type. It is shown that to quantify the spectral dependences in the region of the plasmon absorption band of nanoparticles, correction of the parameters of the interband absorption is necessary in addition to the increase of the relaxation parameter of the Drude theory. Spectral dependences of the dielectric permittivity of gold in nanodimensional state are refined from the solution of the inverse problem. The results of the present work are important for predicting the special features of operation of photonic devices and optical detonators based on gold nanoparticles.

  16. Determination of lead at trace levels in mussel and sea water samples using vortex assisted dispersive liquid-liquid microextraction-slotted quartz tube-flame atomic absorption spectrometry.

    PubMed

    Erarpat, Sezin; Özzeybek, Gözde; Chormey, Dotse Selali; Bakırdere, Sezgin

    2017-12-01

    In this study, dispersive liquid-liquid microextraction (DLLME) and slotted quartz tube (SQT) were coupled to flame atomic absorption spectrometry (FAAS) to increase the sensitivity of lead. Conditions such as the formation of the lead-dithizone complex, efficiency of the DLLME method and the output of the SQT were systematically optimized to improve the detection limit for the analyte. The conventional FAAS system was improved upon by about 3.0 times with SQT-FAAS, 32 times with DLLME-FAAS and 142 times with DLLME-SQT-FAAS. The method was applicable over a wide linear range (10-500 μg L -1 ). The limit of detection (LOD) determined by DLLME-SQT-FAAS for seawater and mussel were 2.7 μg L -1 and 270 μg kg -1 , respectively. The percent recoveries obtained for mussel and seawater samples (spiked at 20 and 50 μg L -1 ) were 95-96% and 98-110%, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Mass spectrometry.

    NASA Technical Reports Server (NTRS)

    Burlingame, A. L.; Johanson, G. A.

    1972-01-01

    Review of the current state of mass spectrometry, indicating its unique importance for advanced scientific research. Mass spectrometry applications in computer techniques, gas chromatography, ion cyclotron resonance, molecular fragmentation and ionization, and isotope labeling are covered. Details are given on mass spectrometry applications in bio-organic chemistry and biomedical research. As the subjects of these applications are indicated alkaloids, carbohydrates, lipids, terpenes, quinones, nucleic acid components, peptides, antibiotics, and human and animal metabolisms. Particular attention is given to the mass spectra of organo-inorganic compounds, inorganic mass spectrometry, surface phenomena such as secondary ion and electron emission, and elemental and isotope analysis. Further topics include mass spectrometry in organic geochemistry, applications in geochronology and cosmochemistry, and organic mass spectrometry.

  18. One-step displacement dispersive liquid-liquid microextraction coupled with graphite furnace atomic absorption spectrometry for the selective determination of methylmercury in environmental samples.

    PubMed

    Liang, Pei; Kang, Caiyan; Mo, Yajun

    2016-01-01

    A novel method for the selective determination of methylmercury (MeHg) was developed by one-step displacement dispersive liquid-liquid microextraction (D-DLLME) coupled with graphite furnace atomic absorption spectrometry. In the proposed method, Cu(II) reacted with diethyldithiocarbamate (DDTC) to form Cu-DDTC complex, which was used as the chelating agent instead of DDTC for the dispersive liquid-liquid microextraction (DLLME) of MeHg. Because the stability of MeHg-DDTC is higher than that of Cu-DDTC, MeHg can displace Cu from the Cu-DDTC complex and be preconcentrated in a single DLLME procedure. MeHg could be extracted into the extraction solvent phase at pH 6 while Hg(II) remained in the sample solution. Potential interference from co-existing metal ions with lower DDTC complex stability was largely eliminated without the need of any masking reagent. Under the optimal conditions, the limit of detection of this method was 13.6ngL(-1) (as Hg), and an enhancement factor of 81 was achieved with a sample volume of 5.0mL. The proposed method was successfully applied for the determination of trace MeHg in some environmental samples with satisfactory results. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Investigation of chemical modifiers for the direct determination of arsenic in fish oil using high-resolution continuum source graphite furnace atomic absorption spectrometry.

    PubMed

    Pereira, Éderson R; de Almeida, Tarcísio S; Borges, Daniel L G; Carasek, Eduardo; Welz, Bernhard; Feldmann, Jörg; Campo Menoyo, Javier Del

    2016-04-01

    High-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) has been applied for the development of a method for the determination of total As in fish oil samples using direct analysis. The method does not use any sample pretreatment, besides dilution with 1-propanole, in order to decrease the oil viscosity. The stability and sensitivity of As were evaluated using ruthenium and iridium as permanent chemical modifiers and palladium added in solution over the sample. The best results were obtained with ruthenium as the permanent modifier and palladium in solution added to samples and standard solutions. Under these conditions, aqueous standard solutions could be used for calibration for the fish oil samples diluted with 1-propanole. The pyrolysis and atomization temperatures were 1400 °C and 2300 °C, respectively, and the limit of detection and characteristic mass were 30 pg and 43 pg, respectively. Accuracy and precision of the method have been evaluated using microwave-assisted acid digestion of the samples with subsequent determination by HR-CS GF AAS and ICP-MS; the results were in agreement (95% confidence level) with those of the proposed method. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Differential determination of chromium(VI) and total chromium in natural waters using flow injection on-line separation and preconcentration electrothermal atomic absorption spectrometry.

    PubMed

    Sperling, M; Yin, X; Welz, B

    1992-03-01

    A rapid, sensitive and selective method for the differential determination of CrIII and CrVI in natural waters is described. Chromium(vi) can be determined directly by flow injection on-line sorbent extraction preconcentration coupled with electrothermal atomic absorption spectrometry using sodium diethyldithiocarbamate as the complexing agent and C18 bonded silica reversed-phase sorbent as the column material. Total Cr can be determined after oxidation of CrIII to CrVI by potassium peroxydisulfate. Chromium(III) can be calculated by difference. The optimum conditions for sorbent extraction of CrVI and oxidation of CrIII to CrVI are evaluated. A 12-fold enhancement in sensitivity compared with direct introduction of 40 microliters samples was achieved after preconcentration for 60 s, giving detection limits of 16 ng l-1 for CrVI and 18 ng l-1 for total Cr (based on 3 sigma). Results obtained for sea-water and river water reference materials were all within the certified range for total Cr with a precision of better than 10% relative standard deviation in the range 100-200 ng l-1. The selectivity of the determination of CrVI was evaluated by analysing spiked reference materials in the presence of CrIII, resulting in quantitative recovery of CrVI.

  1. Unbiased and targeted mass spectrometry for the HDL proteome.

    PubMed

    Singh, Sasha A; Aikawa, Masanori

    2017-02-01

    Mass spectrometry is an ever evolving technology that is equipped with a variety of tools for protein research. Some lipoprotein studies, especially those pertaining to HDL biology, have been exploiting the versatility of mass spectrometry to understand HDL function through its proteome. Despite the role of mass spectrometry in advancing research as a whole, however, the technology remains obscure to those without hands on experience, but still wishing to understand it. In this review, we walk the reader through the coevolution of common mass spectrometry workflows and HDL research, starting from the basic unbiased mass spectrometry methods used to profile the HDL proteome to the most recent targeted methods that have enabled an unprecedented view of HDL metabolism. Unbiased global proteomics have demonstrated that the HDL proteome is organized into subgroups across the HDL size fractions providing further evidence that HDL functional heterogeneity is in part governed by its varying protein constituents. Parallel reaction monitoring, a novel targeted mass spectrometry method, was used to monitor the metabolism of HDL apolipoproteins in humans and revealed that apolipoproteins contained within the same HDL size fraction exhibit diverse metabolic properties. Mass spectrometry provides a variety of tools and strategies to facilitate understanding, through its proteins, the complex biology of HDL.

  2. Time-resolved photoion imaging spectroscopy: Determining energy distribution in multiphoton absorption experiments

    NASA Astrophysics Data System (ADS)

    Qian, D. B.; Shi, F. D.; Chen, L.; Martin, S.; Bernard, J.; Yang, J.; Zhang, S. F.; Chen, Z. Q.; Zhu, X. L.; Ma, X.

    2018-04-01

    We propose an approach to determine the excitation energy distribution due to multiphoton absorption in the case of excited systems following decays to produce different ion species. This approach is based on the measurement of the time-resolved photoion position spectrum by using velocity map imaging spectrometry and an unfocused laser beam with a low fluence and homogeneous profile. Such a measurement allows us to identify the species and the origin of each ion detected and to depict the energy distribution using a pure Poisson's equation involving only one variable which is proportional to the absolute photon absorption cross section. A cascade decay model is used to build direct connections between the energy distribution and the probability to detect each ionic species. Comparison between experiments and simulations permits the energy distribution and accordingly the absolute photon absorption cross section to be determined. This approach is illustrated using C60 as an example. It may therefore be extended to a wide variety of molecules and clusters having decay mechanisms similar to those of fullerene molecules.

  3. Selenium analysis by an integrated microwave digestion-needle trap device with hydride sorption on carbon nanotubes and electrothermal atomic absorption spectrometry determination

    NASA Astrophysics Data System (ADS)

    Maratta Martínez, Ariel; Vázquez, Sandra; Lara, Rodolfo; Martínez, Luis Dante; Pacheco, Pablo

    2018-02-01

    An integrated microwave assisted digestion (MW-AD) - needle trap device (NTD) for selenium determination in grape pomace samples is presented. The NTD was filled with oxidized multiwall carbon nanotubes (oxMWCNTS) where Se hydrides were preconcentrated. Determination was carried out by flow injection-electrothermal atomic absorption spectrometry (FI-ETAAS). The variables affecting the system were established by a multivariate design (Plackett Burman), indicating that the following variables significantly affect the system: sample amount, HNO3 digestion solution concentration, NaBH4 volume and elution volume. A Box-Behnken design was implemented to determine the optimized values of these variables. The system improved Se atomization in the graphite furnace, since only trapped hydrides reached the graphite furnace, and the pyrolysis stage was eliminated according to the aqueous matrix of the eluate. Under optimized conditions the system reached a limit of quantification of 0.11 μg kg- 1, a detection limit of 0.032 μg kg- 1, a relative standard deviation of 4% and a preconcentration factor (PF) of 100, reaching a throughput sample of 5 samples per hour. Sample analysis show Se concentrations between 0.34 ± 0.03 μg kg- 1 to 0.48 ± 0.03 μg kg- 1 in grape pomace. This system provides minimal reagents and sample consumption, eliminates discontinuous stages between samples processing reaching a simpler and faster Se analysis.

  4. Development of a flow system for the determination of cadmium in fuel alcohol using vermicompost as biosorbent and flame atomic absorption spectrometry.

    PubMed

    Bianchin, Joyce Nunes; Martendal, Edmar; Mior, Renata; Alves, Vanessa Nunes; Araújo, Cleide Sandra Tavares; Coelho, Nívia Maria Melo; Carasek, Eduardo

    2009-04-30

    In this study a method for the determination of cadmium in fuel alcohol using solid-phase extraction with a flow injection analysis system and detection by flame atomic absorption spectrometry was developed. The sorbent material used was a vermicompost commonly used as a garden fertilizer. The chemical and flow variables of the on-line preconcentration system were optimized by means of a full factorial design. The selected factors were: sorbent mass, sample pH, buffer concentration and sample flow rate. The optimum extraction conditions were obtained using sample pH in the range of 7.3-8.3 buffered with tris(hydroxymethyl)aminomethane at 50 mmol L(-1), a sample flow rate of 4.5 mL min(-1) and 160 mg of sorbent mass. With the optimized conditions, the preconcentration factor, limit of detection and sample throughput were estimated as 32 (for preconcentration of 10 mL sample), 1.7 microg L(-1) and 20 samples per hour, respectively. The analytical curve was linear from 5 up to at least 50 microg L(-1), with a correlation coefficient of 0.998 and a relative standard deviation of 2.4% (35 microg L(-1), n=7). The developed method was successfully applied to spiked fuel alcohol, and accuracy was assessed through recovery tests, with recovery ranging from 94% to 100%.

  5. A reduced-scale railway noise barrier's insertion loss and absorption coefficients: comparison of field measurements and predictions

    NASA Astrophysics Data System (ADS)

    Busch, T. A.; Nugent, R. E.

    2003-10-01

    In situ testing determined the insertion loss ( IL) and absorption coefficients of a candidate absorptive noise barrier (soundwall) to abate railway noise for residents of Anaheim, CA. A 4000 m barrier is proposed south of the tracks, but residential areas to the north have expressed concerns that barrier reflections will increase their noise exposure. To address these concerns, a 3.66 m high by 14.6 m long demonstration barrier was built in the parking lot of Edison Field, Anaheim, as part of a public open house, thereby allowing for acoustical measurements. Insertion loss ( IL) was measured in third-octave bands assuming 1/2-scale construction. The IL for three, scaled railway noise sub-sources (rail/wheel interface, locomotive, and train horn) was measured at six, scaled distances. The highest total, A-weighted IL, after corrections for finite-barrier and point-source speaker effects was 22 dB(A) for rail/wheel noise, 18 dB(A) for locomotive noise, and 20 dB(A) for train horn noise. These results can be compared favourably to IL predictions made using algorithms from the US Federal Rail Administration (FRA) noise assessment guidelines. For the actual barrier installation, shielded residential receivers located south of the project are expected to see their future noise exposures reduced from an unmitigated 78 CNEL to 65 CNEL. Absorption coefficients were measured using time delay spectrometry. At lower frequencies, measured absorption coefficients were notably less than the reverberation room results advertised in the manufacturer's literature, but generally conformed with impedance tube results. At higher frequencies the correspondence between measured absorption coefficients and reverberation room results was much improved. For the actual barrier installation, unshielded residential receivers to the north are expected to experience noise exposure increases of less than 1 dB(A). This factor of increase is consistent with a finding of no impact when assessed

  6. Fast arsenic speciation in water by on-site solid phase extraction and high-resolution continuum source graphite furnace atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Mihucz, Victor G.; Bencs, László; Koncz, Kornél; Tatár, Enikő; Weiszburg, Tamás; Záray, Gyula

    2017-02-01

    A method of high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS-GFAAS), combined with on-site separation/solid phase extraction (SPE) has been developed for the speciation of inorganic As (iAs) in geothermal and drinking water samples. The HR-CS-GFAAS calibration curves were linear up to 200 μg/L As, but using second order polynomial fitting, accurate calibration could be performed up to 500 μg/L. It has been demonstrated that sample pH should not be higher than 8 for an accurate speciation of As(V) with a recovery of ≈ 95%. Geothermal water had fairly high salt content (≈ 2200 mg/L) due to the presence of chlorides and sulfates at mg/L levels. Therefore, a two-fold dilution of these types of samples before SPE is recommended, especially, for total As determinations, when the As concentration is as high as 400 μg/L. For drinking water, sampled from public wells with records of As concentrations higher than the 10 μg/L in the past, the reduction of As contamination below the WHO's health limit value could be observed. However, the electrical conductivity was close to 2500 μS/cm, i.e., the guideline limit for drinking water, which was due to their higher chloride content. The proposed fit-for-purpose SPE-HR-CS-GFAAS method could be a candidate for screening drinking water quality.

  7. Identification and Characterization of Visible Absorption Components in Aqueous Methylglyoxal-Ammonium Sulfate Mixtures

    NASA Astrophysics Data System (ADS)

    McGivern, W. S.; Allison, T. C.; Radney, J. G.; Zangmeister, C. D.

    2014-12-01

    The aqueous reaction of methylglyoxal (MG) with ammonium sulfate has been suggested as a source of atmospheric ``brown carbon.'' We have utilized high-performance liquid chromatography coupled to ultraviolet-visible spectroscopy and tandem mass spectrometry to study the products of this reaction at high concentrations. The overall product spectrum shows a large number of distinct components; however, the visible absorption from this mixture is derived a very small number of components. The largest contributor is an imine-substituted (C=N-H) product of aldol condensation/facile dehydration reaction between the parent MG and a hydrated product of the MG + ammonia reaction. The asymmetric nature of this compound relative to the aldol condensation of two MG results in a sufficiently large redshift of the UV absorption spectrum that absorption of visible radiation can occur in the long-wavelength tail. The simplicity of the imine products is a result of a strong bias toward ketimine products due to the extensive hydration of the aldehydic moiety in the parent in aqueous solution. In addition, a strong pH dependence of the absorption cross section was observed with significantly greater absorption under more basic conditions. We have performed time-dependent density functional theory calculations to evaluate the absorption spectra of all of the possible condensation products and their respective ions, and the results are consistent with the experimental observations. We have also observed smaller concentrations of other condensation products of the imine-substituted parent species that do not contribute significantly to the visible absorption but have not been previously discussed.

  8. Extraction method based on emulsion breaking for the determination of Cu, Fe and Pb in Brazilian automotive gasoline samples by high-resolution continuum source flame atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Leite, Clarice C.; de Jesus, Alexandre; Kolling, Leandro; Ferrão, Marco F.; Samios, Dimitrios; Silva, Márcia M.

    2018-04-01

    This work reports a new method for extraction of Cu, Fe and Pb from Brazilian automotive gasoline and their determination by high-resolution continuous source flame atomic absorption spectrometry (HR-CS FAAS). The method was based on the formation of water-in-oil emulsion by mixing 2.0 mL of extraction solution constituted by 12% (w/v) Triton X-100 and 5% (v/v) HNO3 with 10 mL of sample. After heating at 90 °C for 10 min, two well-defined phases were formed. The bottom phase (approximately 3.5 mL), composed of acidified water and part of the ethanol originally present in the gasoline sample, containing the extracted analytes was analyzed. The surfactant and HNO3 concentrations and the heating temperature employed in the process were optimized by Doehlert design, using a Brazilian gasoline sample spiked with Cu, Fe and Pb (organometallic compounds). The efficiency of extraction was investigated and it ranged from 80 to 89%. The calibration was accomplished by using matrix matching method. For this, the standards were obtained performing the same extraction procedure used for the sample, using emulsions obtained with a gasoline sample free of analytes and the addition of inorganic standards. Limits of detection obtained were 3.0, 5.0 and 14.0 μg L-1 for Cu, Fe and Pb, respectively. These limits were estimated for the original sample taking into account the preconcentration factor obtained. The accuracy of the proposed method was assured by recovery tests spiking the samples with organometallic standards and the obtained values ranged from 98 to 105%. Ten gasoline samples were analyzed and Fe was found in four samples (0.04-0.35 mg L-1) while Cu (0.28 mg L-1) and Pb (0.60 mg L-1) was found in just one sample.

  9. Transmission ultrasonography. [time delay spectrometry for soft tissue transmission imaging

    NASA Technical Reports Server (NTRS)

    Heyser, R. C.; Le Croissette, D. H.

    1973-01-01

    Review of the results of the application of an advanced signal-processing technique, called time delay spectrometry, in obtaining soft tissue transmission images by transmission ultrasonography, both in vivo and in vitro. The presented results include amplitude ultrasound pictures and phase ultrasound pictures obtained by this technique. While amplitude ultrasonographs of tissue are closely analogous to X-ray pictures in that differential absorption is imaged, phase ultrasonographs represent an entirely new source of information based on differential time of propagation. Thus, a new source of information is made available for detailed analysis.

  10. Microwave absorption in substances that form hydration layers with water

    NASA Astrophysics Data System (ADS)

    Garner, H. R.; Ohkawa, T.; Tuason, O.; Lee, R. L.

    1990-12-01

    The microwave absorption of certain water soluble polymers (polyethylene glycol, polyvinyl pyrrolidone, proteins, and DNA) in solution is composed of three parts: absorption in the free water, absorption in the substance, and absorption in the hydration layer. Ethanol, sucrose, glycerol, and sodium acetate, which form weak hydrogen bonds or have an ionic nature in aqueous solutions, also have microwave absorption signatures similar to polymers that form hydration layers. The frequency-dependent absorption of the free water and of the hydration layer water is described by a simple Debye relaxation model. The absorption per unit sample volume attributable to the hydration layer is solute concentration dependent, and a simple model is used to describe the dependence. The hydration-layer relaxation time was found to vary from substance to substance and with solute concentration. The relaxation time was also found to be independent of solute length.

  11. Mass spectrometry in grape and wine chemistry. Part I: polyphenols.

    PubMed

    Flamini, Riccardo

    2003-01-01

    Mass spectrometry, had and still has, a very important role for research and quality control in the viticulture and enology field, and its analytical power is relevant for structural studies on aroma and polyphenolic compounds. Polyphenols are responsible for the taste and color of wine, and confer astringency and structure to the beverage. The knowledge of the anthocyanic structure is very important to predict the aging attitude of wine, and to attempt to resolve problems about color stability. Moreover, polyphenols are the main compounds related to the benefits of wine consumption in the diet, because of their properties in the treatment of circulatory disorders such as capillary fragility, peripheral chronic venous insufficiency, and microangiopathy of the retina. Liquid Chromatography-Mass Spectrometry (LC-MS) techniques are nowadays the best analytical approach to study polyphenols in grape extracts and wine, and are the most effective tool in the study of the structure of anthocyanins. The MS/MS approach is a very powerful tool that permits anthocyanin aglycone and sugar moiety characterization. LC-MS allows the characterization of complex structures of grape polyphenols, such as procyanidins, proanthocyanidins, prodelphinidins, and tannins, and provides experimental evidence for structures that were previously only hypothesized. The matrix-assisted-laser-desorption-ionization-time-of-flight (MALDI-TOF) technique is suitable to determine the presence of molecules of higher molecular weight with high accuracy, and it has been applied with success to study procyanidin oligomers up to heptamers in the reflectron mode, and up to nonamers in the linear mode. The levels of resveratrol in wine, an important polyphenol well-known for its beneficial effects, have been determined by SPME and LC-MS, and the former approach led to the best results in terms of sensitivity. Copyright 2003 Wiley Periodicals, Inc.

  12. Energy absorption in composite materials for crashworthy structures

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.

    1987-01-01

    Crash energy-absorption processes in composite materials have been studied as part of a research program aimed at the development of energy absorbing subfloor beams for crashworthy military helicopters. Based on extensive tests on glass/epoxy, graphite/epoxy, and Kevlar/epoxy composites, it is shown that the energy-absorption characteristics and crushing modes of composite beams are similar to those exhibited by tubular specimens of similar material and architecture. The crushing mechanisms have been determined and related to the mechanical properties of the constituent materials and specimen architecture. A simple and accurate method for predicting the energy-absorption capability of composite beams has been developed.

  13. 40 CFR 1065.1010 - Reference materials.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... § 1065.1010—Institute of Petroleum Materials Document No. and name Part 1065 reference IP-470... atomic absorption spectrometry 1065.705 IP-500, Determination of the phosphorus content of residual fuels by ultra-violet spectrometry 1065.705 IP-501, Determination of aluminum, silicon, vanadium, nickel...

  14. Combustion chemistry and flame structure of furan group biofuels using molecular-beam mass spectrometry and gas chromatography - Part II: 2-Methylfuran.

    PubMed

    Tran, Luc-Sy; Togbé, Casimir; Liu, Dong; Felsmann, Daniel; Oßwald, Patrick; Glaude, Pierre-Alexandre; Fournet, René; Sirjean, Baptiste; Battin-Leclerc, Frédérique; Kohse-Höinghaus, Katharina

    2014-03-01

    This is Part II of a series of three papers which jointly address the combustion chemistry of furan and its alkylated derivatives 2-methylfuran (MF) and 2,5-dimethylfuran (DMF) under premixed low-pressure flame conditions. Some of them are considered to be promising biofuels. With furan as a common basis studied in Part I of this series, the present paper addresses two laminar premixed low-pressure (20 and 40 mbar) flat argon-diluted (50%) flames of MF which were studied with electron-ionization molecular-beam mass spectrometry (EI-MBMS) and gas chromatography (GC) for equivalence ratios φ=1.0 and 1.7, identical conditions to those for the previously reported furan flames. Mole fractions of reactants, products as well as stable and reactive intermediates were measured as a function of the distance above the burner. Kinetic modeling was performed using a comprehensive reaction mechanism for all three fuels given in Part I and described in the three parts of this series. A comparison of the experimental results and the simulation shows reasonable agreement, as also seen for the furan flames in Part I before. This set of experiments is thus considered to be a valuable additional basis for the validation of the model. The main reaction pathways of MF consumption have been derived from reaction flow analyses, and differences to furan combustion chemistry under the same conditions are discussed.

  15. Controlling enhanced absorption in graphene metamaterial

    NASA Astrophysics Data System (ADS)

    Zhou, Qihui; Liu, Peiguo; Bian, Li-an; Liu, Hanqing; Liu, Chenxi; Chen, Genghui

    2018-04-01

    In this paper, a controllable terahertz (THz) metamaterial absorber (MA) is designed with the circuit analog method. Taking advantage of the patterned graphene on SiO2/doped Si/polyimide substrates with a gold reflector, the controllable MA achieves perfect absorption at 0.75 THz. The chemical potential of graphene is regulated by controlling the voltage between graphene and doped Si layers. As the chemical potential varies from 0 eV to 0.5 eV, the MA is changed from reflection (<0.37) to absorption (>0.99). The distributions of surface current and electric field are illustrated to analyze the resonant characteristic of patterned graphene. According to the resonant characteristic, we introduce patterned graphene elements with different dimension in a unit cell, which effectively extends the effective absorption bandwidth (absorption > 0 . 9) from 0.67-0.93 THz to 0.52-0.95 THz. Moreover, replacing part of the graphene structure with gold, the switchable MA is turned into a frequency tunable MA. The absorption peak moves from 0.62 THz to 0.92 THz as the chemical potential increases from 0.1 eV to 0.5 eV. These designs overcome limitation of traditional absorbers and exhibit great potentials in many practical applications.

  16. Matrix Optical Absorption in UV-MALDI MS.

    PubMed

    Robinson, Kenneth N; Steven, Rory T; Bunch, Josephine

    2018-03-01

    In ultraviolet matrix-assisted laser desorption/ionization mass spectrometry (UV-MALDI MS) matrix compound optical absorption governs the uptake of laser energy, which in turn has a strong influence on experimental results. Despite this, quantitative absorption measurements are lacking for most matrix compounds. Furthermore, despite the use of UV-MALDI MS to detect a vast range of compounds, investigations into the effects of laser energy have been primarily restricted to single classes of analytes. We report the absolute solid state absorption spectra of the matrix compounds α-cyano-4-hydroxycinnamic acid (CHCA), para-nitroaniline (PNA), 2-mercaptobenzothiazole (MBT), 2,5-dihydroxybenzoic acid (2,5-DHB), and 2,4,6-trihydroxyacetophenone (THAP). The desorption/ionization characteristics of these matrix compounds with respect to laser fluence was investigated using mixed systems of matrix with either angiotensin II, PC(34:1) lipid standard, or haloperidol, acting as representatives for typical classes of analyte encountered in UV-MALDI MS. The first absolute solid phase spectra for PNA, MBT, and THAP are reported; additionally, inconsistencies between previously published spectra for CHCA are resolved. In light of these findings, suggestions are made for experimental optimization with regards to matrix and laser wavelength selection. The relationship between matrix optical cross-section and wavelength-dependant threshold fluence, fluence of maximum ion yield, and R, a new descriptor for the change in ion intensity with fluence, are described. A matrix cross-section of 1.3 × 10 -17 cm -2 was identified as a potential minimum for desorption/ionization of analytes. Graphical Abstract ᅟ.

  17. Matrix Optical Absorption in UV-MALDI MS

    NASA Astrophysics Data System (ADS)

    Robinson, Kenneth N.; Steven, Rory T.; Bunch, Josephine

    2018-03-01

    In ultraviolet matrix-assisted laser desorption/ionization mass spectrometry (UV-MALDI MS) matrix compound optical absorption governs the uptake of laser energy, which in turn has a strong influence on experimental results. Despite this, quantitative absorption measurements are lacking for most matrix compounds. Furthermore, despite the use of UV-MALDI MS to detect a vast range of compounds, investigations into the effects of laser energy have been primarily restricted to single classes of analytes. We report the absolute solid state absorption spectra of the matrix compounds α-cyano-4-hydroxycinnamic acid (CHCA), para-nitroaniline (PNA), 2-mercaptobenzothiazole (MBT), 2,5-dihydroxybenzoic acid (2,5-DHB), and 2,4,6-trihydroxyacetophenone (THAP). The desorption/ionization characteristics of these matrix compounds with respect to laser fluence was investigated using mixed systems of matrix with either angiotensin II, PC(34:1) lipid standard, or haloperidol, acting as representatives for typical classes of analyte encountered in UV-MALDI MS. The first absolute solid phase spectra for PNA, MBT, and THAP are reported; additionally, inconsistencies between previously published spectra for CHCA are resolved. In light of these findings, suggestions are made for experimental optimization with regards to matrix and laser wavelength selection. The relationship between matrix optical cross-section and wavelength-dependant threshold fluence, fluence of maximum ion yield, and R, a new descriptor for the change in ion intensity with fluence, are described. A matrix cross-section of 1.3 × 10-17 cm-2 was identified as a potential minimum for desorption/ionization of analytes.

  18. Trace Element Analysis of Biological Samples.

    ERIC Educational Resources Information Center

    Veillon, Claude

    1986-01-01

    Reviews background of atomic absorption spectrometry techniques. Discusses problems encountered and precautions to be taken in determining trace elements in the parts-per-billion concentration range and below. Concentrates on determining chromium in biological samples by graphite furnace atomic absorption. Considers other elements, matrices, and…

  19. Determination of sulphur in various vegetables by solid sampling high-resolution electrothermal molecular absorption spectrometry.

    PubMed

    Gunduz, Sema; Akman, Suleyman

    2015-04-01

    Sulphur was determined in various vegetables via molecular absorption of carbon monosulphide (CS) at 258.056 nm using a solid sampling high resolution continuum source electrothermal atomic absorption spectrometer (SS HR-CS ETAAS). Samples were dried, ground and directly introduced into the ruthenium coated graphite furnace as 0.05 to 0.50mg. All determinations were performed using palladium+citric acid modifier and applying a pyrolysis temperature of 1000 °C and a volatilisation temperature of 2400 °C. The results were in good agreement with certified sulphur concentrations of various vegetal CRM samples applying linear calibration technique prepared from thioacetamide. The limit of detection and characteristic mass of the method were 7.5 and 8.7 ng of S, respectively. The concentrations of S in various spinach, leek, lettuce, radish, Brussels sprouts, zucchini and chard samples were determined. It was showed that distribution of sulphur in CRM and grinded food samples were homogeneous even in micro-scale. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Magnetic stirrer induced dispersive ionic-liquid microextraction for the determination of vanadium in water and food samples prior to graphite furnace atomic absorption spectrometry.

    PubMed

    Naeemullah; Kazi, Tasneem Gul; Tuzen, Mustafa

    2015-04-01

    A new dispersive liquid-liquid microextraction, magnetic stirrer induced dispersive ionic-liquid microextraction (MS-IL-DLLME) was developed to quantify the trace level of vanadium in real water and food samples by graphite furnace atomic absorption spectrometry (GFAAS). In this extraction method magnetic stirrer was applied to obtained a dispersive medium of 1-butyl-3-methylimidazolium hexafluorophosphate [C4MIM][PF6] in aqueous solution of (real water samples and digested food samples) to increase phase transfer ratio, which significantly enhance the recovery of vanadium - 4-(2-pyridylazo) resorcinol (PAR) chelate. Variables having vital role on desired microextraction methods were optimised to obtain the maximum recovery of study analyte. Under the optimised experimental variables, enhancement factor (EF) and limit of detection (LOD) were achieved to be 125 and 18 ng L(-1), respectively. Validity and accuracy of the desired method was checked by analysis of certified reference materials (SLRS-4 Riverine water and NIST SRM 1515 Apple leaves). The relative standard deviation (RSD) for 10 replicate determinations at 0.5 μg L(-1) of vanadium level was found to be <5.0%. This method was successfully applied to real water and acid digested food samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Ion Mobility Spectrometry-Hydrogen Deuterium Exchange Mass Spectrometry of Anions: Part 2. Assessing Charge Site Location and Isotope Scrambling

    NASA Astrophysics Data System (ADS)

    Khakinejad, Mahdiar; Ghassabi Kondalaji, Samaneh; Donohoe, Gregory C.; Valentine, Stephen J.

    2016-03-01

    Ion mobility spectrometry (IMS) coupled with gas-phase hydrogen deuterium exchange (HDX)-mass spectrometry (MS) and molecular dynamic simulations (MDS) has been used for structural investigation of anions produced by electrospraying a sample containing a synthetic peptide having the sequence KKDDDDDIIKIIK. In these experiments the potential of the analytical method for locating charge sites on ions as well as for utilizing collision-induced dissociation (CID) to reveal the degree of deuterium uptake within specific amino acid residues has been assessed. For diffuse (i.e., more elongated) [M - 2H]2- ions, decreased deuterium content along with MDS data suggest that the D4 and D6 residues are charge sites, whereas for the more diffuse [M - 3H]3- ions, the data suggest that the D4, D7, and the C-terminus are deprotonated. Fragmentation of mobility-selected, diffuse [M - 2H]2- ions to determine deuterium uptake at individual amino acid residues reveals a degree of deuterium retention at incorporation sites. Although the diffuse [M - 3H]3- ions may show more HD scrambling, it is not possible to clearly distinguish HD scrambling from the expected deuterium uptake based on a hydrogen accessibility model. The capability of the IMS-HDX-MS/MS approach to provide relevant details about ion structure is discussed. Additionally, the ability to extend the approach for locating protonation sites on positively-charged ions is presented.

  2. New in situ Aerosol Spectral Optical Measurements over 300-700 nm, Extinction and Total Absorption, Paired with Absorption from Water- and Methanol-soluble Aerosol Extracts

    NASA Astrophysics Data System (ADS)

    Jordan, C. E.; Stauffer, R. M.; Lamb, B.; Novak, M. G.; Mannino, A.; Hudgins, C.; Thornhill, K. L., II; Crosbie, E.; Winstead, E.; Anderson, B.; Martin, R.; Shook, M.; Ziemba, L. D.; Beyersdorf, A. J.; Corr, C.

    2017-12-01

    A new in situ spectral aerosol extinction instrument (custom built, SpEx) built to cover the 300-700 nm range at 1 nm spectral resolution and temporal resolution of 4 minutes was deployed on the top deck ( 10 m above the water surface) of the R/V Onnuri during the KORUS-OC research cruise around South Korea in spring 2016. This new instrument was one component of a suite of in situ aerosol optical measurements that included 3-visible-wavelength scattering (Airphoton IN101 Nephelometer, at 450, 532, & 632 nm) and absorption (Brechtel Tricolor Absorption Photometer Model 2901, at 467, 528, & 652 nm) with sub-minute temporal resolution; two sets of filters (Teflon and glass fiber, both collected over 3 hour daytime and 12 hour overnight intervals) to provide aerosol absorption spectra over the same wavelength range as SpEx. The glass fiber filters were placed in the center of an integrating sphere (Labsphere DRA-CA-30) attached to a dual beam spectrophotometer (Cary 100 Bio UV-Visible Spectrophotometer) to measure total aerosol absorption spectra via an established method used by the ocean color community to obtain absorption spectra from particles suspended in sea water. Adapting this methodology for atmospheric aerosol measurements provides a new avenue to obtain spectral total aerosol absorption, particularly useful for expanding in situ measurement capabilities into the UV range. The Teflon filters were cut in half with one half extracted in deionized water and the other half extracted in methanol. The solutions were filtered and injected into a liquid waveguide capillary cell (World Precision Instruments LWCC-3100, 100 cm pathlength) to measure the absorption spectra for each solution. In addition, the water extracts were measured via ion chromatography (Dionex ICS-3000 Ion Chromatography System) to obtain water-soluble inorganic ion concentrations, as well as via aerosol mass spectrometry (Aerodyne Research, Inc. HR-ToF High Resolution Aerosol Mass Spectrometer

  3. Chemical investigation of saponins in different parts of Panax notoginseng by pressurized liquid extraction and liquid chromatography-electrospray ionization-tandem mass spectrometry.

    PubMed

    Wan, Jian-Bo; Zhang, Qing-Wen; Hong, Si-Jia; Li, Peng; Li, Shao-Ping; Wang, Yi-Tao

    2012-05-16

    A pressurized liquid extraction (PLE) and high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) method was developed for the qualitative determination of saponins in different parts of P. notoginseng, including rhizome, root, fibre root, seed, stem, leaf and flower. The samples were extracted using PLE. The analysis was achieved on a Zorbax SB-C18 column with gradient elution of acetonitrile and 8 mM aqueous ammonium acetate as mobile phase. The mass spectrometer was operated in the negative ion mode using the electrospray ionization, and a collision induced dissociation (CID) experiment was also carried out to aid the identification of compounds. Forty one saponins were identified in different parts of P. notoginseng according to the fragmentation patterns and literature reports, among them, 21 saponins were confirmed by comparing the retention time and ESI-MS data with those of standard compounds. The results showed that the chemical characteristics were obviously diverse in different parts of P. notoginseng, which is helpful for pharmacological evaluation and quality control of P. notoginseng.

  4. Determination of fluorine in herbs and water samples by molecular absorption spectrometry after preconcentration on nano-TiO2 using ultrasound-assisted dispersive micro solid phase extraction.

    PubMed

    Krawczyk-Coda, Magdalena; Stanisz, Ewa

    2017-11-01

    This work presents ultrasound-assisted dispersive micro solid phase extraction (USA DMSPE) for preconcentration of fluorine (F) in water and herb samples. TiO 2 nanoparticles (NPs) were used as an adsorbent. The determination with slurry sampling was performed via molecular absorption of calcium monofluoride (CaF) at 606.440 nm using a high-resolution continuum source electrothermal absorption spectrometry (HR-CS ET MAS). Several factors influencing the efficiency of the preconcentration technique, such as the amount of TiO 2 , pH of sample solution, ultrasonication and centrifugation time and TiO 2 slurry solution preparation before injection to HR-CS ET MAS, were investigated in detail. The conditions of detection step (wavelength, calcium amount, pyrolysis and molecule-forming temperatures) were also studied. After extraction, adsorbent with the analyte was mixed with 200 μL of H 2 O to prepare a slurry solution. The concentration limit of detection was 0.13 ng mL -1 . The achieved preconcentration factor was 7. The relative standard deviations (RSDs, %) for F in real samples were 3-15%. The accuracy of this method was evaluated by analyses of certified reference materials after spiking: INCT-MPH-2 (Mixed Polish Herbs), INCT-SBF-4 (Soya Bean Flour), ERM-CAO11b (Hard Drinking Water) and TMDA-54.5 (Lake Ontario Water). The measured F contents in reference materials were in satisfactory agreement with the added amounts, and the recoveries were found to be 97-109%. Under the developed extraction conditions, the proposed method has been successfully applied for the determination of F in real water samples (lake, sea, tap water) and herbs.

  5. A Quantitative Review and Meta-Models of the Variability and Factors Affecting Oral Drug Absorption-Part I: Gastrointestinal pH.

    PubMed

    Abuhelwa, Ahmad Y; Foster, David J R; Upton, Richard N

    2016-09-01

    This study aimed to conduct a quantitative meta-analysis for the values of, and variability in, gastrointestinal (GI) pH in the different GI segments; characterize the effect of food on the values and variability in these parameters; and present quantitative meta-models of distributions of GI pH to help inform models of oral drug absorption. The literature was systemically reviewed for the values of, and the variability in, GI pH under fed and fasted conditions. The GI tract was categorized into the following 10 distinct regions: stomach (proximal, mid-distal), duodenum (proximal, mid-distal), jejunum and ileum (proximal, mid, and distal small intestine), and colon (ascending, transverse, and descending colon). Meta-analysis used the "metafor" package of the R language. The time course of postprandial stomach pH was modeled using NONMEM. Food significantly influenced the estimated meta-mean stomach and duodenal pH but had no significant influence on small intestinal and colonic pH. The time course of postprandial pH was described using an exponential model. Increased meal caloric content increased the extent and duration of postprandial gastric pH buffering. The different parts of the small intestine had significantly different pH. Colonic pH was significantly different for descending but not for ascending and transverse colon. Knowledge of GI pH is important for the formulation design of the pH-dependent dosage forms and in understanding the dissolution and absorption of orally administered drugs. The meta-models of GI pH may also be used as part of semi-physiological pharmacokinetic models to characterize the effect of GI pH on the in vivo drug release and pharmacokinetics.

  6. Determination of silicon and aluminum in silicon carbide nanocrystals by high-resolution continuum source graphite furnace atomic absorption spectrometry.

    PubMed

    Dravecz, Gabriella; Bencs, László; Beke, Dávid; Gali, Adam

    2016-01-15

    The determination of Al contaminant and the main component Si in silicon carbide (SiC) nanocrystals with the size-distribution of 1-8nm dispersed in an aqueous solution was developed using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS-GFAAS). The vaporization/atomization processes were investigated in a transversally heated graphite atomizer by evaporating solution samples of Al and Si preserved in various media (HCl, HNO3). For Si, the best results were obtained by applying a mixture of 5µg Pd plus 5µg Mg, whereas for Al, 10µg Mg (each as nitrate solution) was dispensed with the samples, but the results obtained without modifier were found to be better. This way a maximum pyrolysis temperature of 1200°C for Si and 1300°C for Al could be used, and the optimum (compromise) atomization temperature was 2400°C for both analytes. The Si and Al contents of different sized SiC nanocrystals, dispersed in aqueous solutions, were determined against aqueous (external) calibration standards. The correlation coefficients (R values) of the calibrations were found to be 0.9963 for Si and 0.9991 for Al. The upper limit of the linear calibration range was 2mg/l Si and 0.25mg/l Al. The limit of detection was 3µg/l for Si and 0.5µg/l for Al. The characteristic mass (m0) was calculated to be 389pg Si and 6.4pg Al. The Si and Al content in the solution samples were found to be in the range of 1.0-1.7mg/l and 0.1-0.25mg/l, respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Lead and cadmium in human placentas and maternal and neonatal blood (in a heavily polluted area) measured by graphite furnace atomic absorption spectrometry.

    PubMed Central

    Baranowska, I

    1995-01-01

    OBJECTIVE--To measure the concentrations of the trace elements lead and cadmium in human placenta and in maternal and neonatal (cord) blood. To assess the influence of the strongly polluted environment on the content of metals in tissues and on the permeability of placenta to cadmium and lead. Various methods of mineralisation were tested before analysis. METHODS--Graphite furnace atomic absorption spectrometry was used for the determination of lead and cadmium. The samples for analysis were prepared by mineralisation under pressure in a Teflon bomb (HNO3, 110 degrees C), by wet ashing under normal pressure (HNO3 + H2O2 for 12 hours), and by microwave digestion in concentrated nitric acid. RESULTS--In analysed samples the following mean concentrations of cadmium and lead were found: in venous blood Pb = 72.50 ng/ml, Cd = 4.90 ng/ml; in placenta Pb = 0.50 microgram/g, Cd = 0.11 microgram/g; in cord blood Pb = 38.31 ng/ml, Cd = 1.13 ng/ml. CONCLUSION--High concentrations of lead and cadmium were found in placentas and in maternal blood whereas in neonatal blood there was an increased concentration of lead and only traces of cadmium. It is concluded that the placenta is a better barrier for cadmium than for lead. Among the examined methods of mineralisation, microwave digestion was the best. PMID:7795737

  8. Discovery of Hα Absorption in the Unusual Broad Absorption Line Quasar SDSS J083942.11+380526.3

    NASA Astrophysics Data System (ADS)

    Aoki, Kentaro; Iwata, Ikuru; Ohta, Kouji; Ando, Masataka; Akiyama, Masayuki; Tamura, Naoyuki

    2006-11-01

    We discovered Hα absorption in the broad Hα emission line of an unusual broad absorption line quasar, SDSS J083942.11+380526.3, at z=2.318, through near-infrared spectroscopy with the Cooled Infrared Spectrograph and Camera for OHS (CISCO) on the Subaru telescope. The presence of nonstellar Hα absorption is known only in the Seyfert galaxy NGC 4151 to date; thus, our discovery is the first case for quasars. The Hα absorption line is blueshifted by 520 km s-1 relative to the Hα emission line, and its redshift almost coincides with those of UV low-ionization metal absorption lines. The width of the Hα absorption (~340 km s-1) is similar to those of the UV low-ionization absorption lines. These facts suggest that the Hα and low-ionization metal absorption lines are produced by the same low-ionization gas, which has a substantial amount of neutral gas. The column density of the neutral hydrogen is estimated to be ~1018 cm-2 by assuming a gas temperature of 10,000 K from the analysis of the curve of growth. The continuum spectrum is reproduced by a reddened [E(B-V)~0.15 mag for the SMC-like reddening law] composite quasar spectrum. Furthermore, the UV spectrum of SDSS J083942.11+380526.3 shows a remarkable similarity to that of NGC 4151 in its low state, suggesting that the physical condition of the absorber in SDSS J083942.11+380526.3 is similar to that of NGC 4151 in the low state. As proposed for NGC 4151, SDSS J083942.11+380526.3 may also be seen through the edge of the obscuring torus. Based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

  9. Isolated human and animal stratum corneum as a partial model for the 15 steps of percutaneous absorption: emphasizing decontamination, part II.

    PubMed

    Hui, Xiaoying; Lamel, Sonia; Qiao, Peter; Maibach, Howard I

    2013-03-01

    Cutaneously directed chemical warfare agents can elicit significant morbidity and mortality. The optimization of prophylactic and therapeutic interventions counteracting these agents is crucial, and the development of decontamination protocols and methodology of post dermal exposure risk assessments would be additionally applicable to common industrial and consumer dermatotoxicants. Percutaneous (PC) penetration is often considered a simple one-step diffusion process but presently consists of at least 15 steps. The systemic exposure to an agent depends on multiple factors and the second part of this review covers absorption and excretion kinetics, wash and rub effects, skin substantivity and transfer, among others. Importantly, the partitioning behavior and diffusion through the stratum corneum (SC) of a wide physicochemical array of compounds shows that many compounds have approximately the same diffusion coefficient which determines their percutaneous absorption in vivo. After accounting for anatomical variation of the SC, the penetration flux value of a substance depends mainly on its SC/vehicle partition coefficient. Additionally, the SC acts as a 'reservoir' for topically applied molecules, and tape stripping methodology can quantify the remaining chemical in the SC which can predict the total molecular penetration in vivo. The determination of ideal decontamination protocols is of utmost importance to reduce morbidity and mortality. However, even expeditious standard washing procedures post dermal chemical exposure often fails to remove chemicals. The second part of this overview continues to review percutaneous penetration extending insights into the complexities of penetration, decontamination and potential newer assays that may be of practical importance. Copyright © 2012 John Wiley & Sons, Ltd.

  10. Supercritical fluid extraction and direct fluid injection mass spectrometry for the determination of trichothecene mycotoxins in wheat samples

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kalinoski, H.T.; Udseth, H.R.; Wright, B.W.

    1986-10-01

    The application of on-line supercritical fluid extraction with chemical ionization mass spectrometry and collision induced dissociation tandem mass spectrometry for the rapid identification of parts-per-million levels of several trichothecene mycotoxins is demonstrated. Supercritical carbon dioxide is shown to allow identification of mycotoxins with minimum sample handling in complex natural matrices (e.g., wheat). Tandem mass spectrometry techniques are employed for unambiguous identification of compounds of varying polarity, and false positives from isobaric compounds are avoided. Capillary column supercritical fluid chromatography-mass spectrometry of a supercritical fluid extract of the same sample was also performed and detection limits in the parts-per-billion range appearmore » feasible.« less

  11. AERONET derived (BC) aerosol absorption

    NASA Astrophysics Data System (ADS)

    Kinne, S.

    2015-12-01

    AERONET is a ground-based sun-/sky-photometer network with good annual statistics at more than 400 sites worldwide. Inversion methods applied to these data define all relevant column aerosol optical properties and reveal even microphysical detail. The extracted data include estimates for aerosol size-distributions and for aerosol refractive indices at four different solar wavelengths. Hereby, the imaginary parts of the refractive indices define the aerosol column absorption. For regional and global averages and radiative impact assessment with off-line radiative transfer, these local data have been extended with distribution patterns offered by AeroCom modeling experiments. Annual and seasonal absorption distributions for total aerosol and estimates for component contributions (such as BC) are presented and associated direct forcing impacts are quantified.

  12. Ethylene hydrogenation catalysis on Pt(111) single-crystal surfaces studied by using mass spectrometry and in situ infrared absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Tillekaratne, Aashani; Simonovis, Juan Pablo; Zaera, Francisco

    2016-10-01

    The catalytic hydrogenation of ethylene promoted by a Pt(111) single crystal was studied by using a ultrahigh-vacuum surface-science instrument equipped with a so-called high-pressure cell. Kinetic data were acquired continuously during the catalytic conversion of atmospheric-pressure mixtures of ethylene and hydrogen by using mass spectrometry while simultaneously characterizing the surface species in operando mode by reflection-absorption infrared spectroscopy (RAIRS). Many observations reported in previous studies of this system were corroborated, including the presence of adsorbed alkylidyne intermediates during the reaction and the zero-order dependence of the rate of hydrogenation on the pressure of ethylene. In addition, the high quality of the kinetic data, which could be recorded continuously versus time and processed to calculate time-dependent turnover frequencies (TOFs), afforded a more detailed analysis of the mechanism. Specifically, deuterium labeling could be used to estimate the extent of isotope scrambling reached with mixed-isotope-substituted reactants (C2H4 + D2 and C2D4 + H2). Perhaps the most important new observation from this work is that, although extensive H-D exchange takes place on ethylene before being fully converted to ethane, the average stoichiometry of the final product retains the expected stoichiometry of the gas mixture, that is, four regular hydrogen atoms and two deuteriums per ethane molecule in the case of the experiments with C2H4 + D2. This means that no hydrogen atoms are removed from the surface via their inter-recombination to produce X2 (X = H or D). It is concluded that, under catalytic conditions, hydrogen surface recombination is much slower than ethylene hydrogenation and H-D exchange.

  13. Cloud point extraction-flame atomic absorption spectrometry for pre-concentration and determination of trace amounts of silver ions in water samples.

    PubMed

    Yang, Xiupei; Jia, Zhihui; Yang, Xiaocui; Li, Gu; Liao, Xiangjun

    2017-03-01

    A cloud point extraction (CPE) method was used as a pre-concentration strategy prior to the determination of trace levels of silver in water by flame atomic absorption spectrometry (FAAS) The pre-concentration is based on the clouding phenomena of non-ionic surfactant, triton X-114, with Ag (I)/diethyldithiocarbamate (DDTC) complexes in which the latter is soluble in a micellar phase composed by the former. When the temperature increases above its cloud point, the Ag (I)/DDTC complexes are extracted into the surfactant-rich phase. The factors affecting the extraction efficiency including pH of the aqueous solution, concentration of the DDTC, amount of the surfactant, incubation temperature and time were investigated and optimized. Under the optimal experimental conditions, no interference was observed for the determination of 100 ng·mL -1 Ag + in the presence of various cations below their maximum concentrations allowed in this method, for instance, 50 μg·mL -1 for both Zn 2+ and Cu 2+ , 80 μg·mL -1 for Pb 2+ , 1000 μg·mL -1 for Mn 2+ , and 100 μg·mL -1 for both Cd 2+ and Ni 2+ . The calibration curve was linear in the range of 1-500 ng·mL -1 with a limit of detection (LOD) at 0.3 ng·mL -1 . The developed method was successfully applied for the determination of trace levels of silver in water samples such as river water and tap water.

  14. Five-Photon Absorption and Selective Enhancement of Multiphoton Absorption Processes

    PubMed Central

    2015-01-01

    We study one-, two-, three-, four-, and five-photon absorption of three centrosymmetric molecules using density functional theory. These calculations are the first ab initio calculations of five-photon absorption. Even- and odd-order absorption processes show different trends in the absorption cross sections. The behavior of all even- and odd-photon absorption properties shows a semiquantitative similarity, which can be explained using few-state models. This analysis shows that odd-photon absorption processes are largely determined by the one-photon absorption strength, whereas all even-photon absorption strengths are largely dominated by the two-photon absorption strength, in both cases modulated by powers of the polarizability of the final excited state. We demonstrate how to selectively enhance a specific multiphoton absorption process. PMID:26120588

  15. Five-Photon Absorption and Selective Enhancement of Multiphoton Absorption Processes.

    PubMed

    Friese, Daniel H; Bast, Radovan; Ruud, Kenneth

    2015-05-20

    We study one-, two-, three-, four-, and five-photon absorption of three centrosymmetric molecules using density functional theory. These calculations are the first ab initio calculations of five-photon absorption. Even- and odd-order absorption processes show different trends in the absorption cross sections. The behavior of all even- and odd-photon absorption properties shows a semiquantitative similarity, which can be explained using few-state models. This analysis shows that odd-photon absorption processes are largely determined by the one-photon absorption strength, whereas all even-photon absorption strengths are largely dominated by the two-photon absorption strength, in both cases modulated by powers of the polarizability of the final excited state. We demonstrate how to selectively enhance a specific multiphoton absorption process.

  16. Molecular dynamics simulations of collision-induced absorption: Implementation in LAMMPS

    NASA Astrophysics Data System (ADS)

    Fakhardji, W.; Gustafsson, M.

    2017-02-01

    We pursue simulations of collision-induced absorption in a mixture of argon and xenon gas at room temperature by means of classical molecular dynamics. The established theoretical approach (Hartmann et al. 2011 J. Chem. Phys. 134 094316) is implemented with the molecular dynamics package LAMMPS. The bound state features in the absorption spectrum are well reproduced with the molecular dynamics simulation in comparison with a laboratory measurement. The magnitude of the computed absorption, however, is underestimated in a large part of the spectrum. We suggest some aspects of the simulation that could be improved.

  17. Simultaneous multielement atomic absorption spectrometry with graphite furnace atomization

    NASA Astrophysics Data System (ADS)

    Harnly, James M.; Miller-Ihli, Nancy J.; O'Haver, Thomas C.

    The extended analytical range capability of a simultaneous multielement atomic absorption continuum source spectrometer (SIMAAC) was tested for furnace atomization with respect to the signal measurement mode (peak height and area), the atomization mode (from the wall or from a platform), and the temperature program mode (stepped or ramped atomization). These parameters were evaluated with respect to the shapes of the analytical curves, the detection limits, carry-over contamination and accuracy. Peak area measurements gave more linear calibration curves. Methods for slowing the atomization step heating rate, the use of a ramped temperature program or a platform, produced similar calibration curves and longer linear ranges than atomization with a stepped temperature program. Peak height detection limits were best using stepped atomization from the wall. Peak area detection limits for all atomization modes were similar. Carry-over contamination was worse for peak area than peak height, worse for ramped atomization than stepped atomization, and worse for atomization from a platform than from the wall. Accurate determinations (100 ± 12% for Ca, Cu, Fe, Mn, and Zn in National Bureau of Standards' Standard Reference Materials Bovine Liver 1577 and Rice Flour 1568 were obtained using peak area measurements with ramped atomization from the wall and stepped atomization from a platform. Only stepped atomization from a platform gave accurate recoveries for K. Accurate recoveries, 100 ± 10%, with precisions ranging from 1 to 36 % (standard deviation), were obtained for the determination of Al, Co, Cr, Fe, Mn, Mo, Ni. Pb, V and Zn in Acidified Waters (NBS SRM 1643 and 1643a) using stepped atomization from a platform.

  18. Synthesis, characterization and application of a new chelating resin for solid phase extraction, preconcentration and determination of trace metals in some dairy samples by flame atomic absorption spectrometry.

    PubMed

    Daşbaşı, Teslima; Saçmacı, Şerife; Çankaya, Nevin; Soykan, Cengiz

    2016-11-15

    In this study, a simple and rapid solid phase extraction/preconcentration procedure was developed for determination of Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Mn(II), Pb(II), and Zn(II) trace metals by flame atomic absorption spectrometry (FAAS). A new chelating resin, poly(N-cyclohexylacrylamide-co-divinylbenzene-co-2-acrylamido-2-methyl-1-propanesulfonic acid) (NCA-co-DVB-co-AMPS) (hereafter CDAP) was synthesized and characterized. The influences of the analytical parameters such as pH of the sample solution, type and concentration of eluent, flow rates of the sample and eluent, volume of the sample and eluent, amount of chelating resin, and interference of ions were examined. The limit of detection (LOD) of analytes were found (3s) to be in the range of 0.65-1.90μgL(-1). Preconcentration factor (PF) of 200 and the relative standard deviation (RSD) of ⩽2% were achieved (n=11). The developed method was applied for determination of analytes in some dairy samples and certified reference materials. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Monitoring spacecraft atmosphere contaminants by laser absorption spectroscopy

    NASA Technical Reports Server (NTRS)

    Steinfeld, J. I.

    1976-01-01

    Laser-based spectrophotometric methods which have been proposed for the detection of trace concentrations of gaseous contaminants include Raman backscattering (LIDAR) and passive radiometry (LOPAIR). Remote sensing techniques using laser spectrometry are presented and in particular a simple long-path laser absorption method (LOLA), which is capable of resolving complex mixtures of closely related trace contaminants at ppm levels is discussed. A number of species were selected for study which are representative of those most likely to accumulate in closed environments, such as submarines or long-duration manned space flights. Computer programs were developed which will permit a real-time analysis of the monitored atmosphere. Estimates of the dynamic range of this monitoring technique for various system configurations, and comparison with other methods of analysis, are given.

  20. Paracetamol absorption from different sites in the human small intestine.

    PubMed Central

    Gramatté, T; Richter, K

    1994-01-01

    Site-specificity in the small intestinal absorption of paracetamol was investigated using a segmental intestinal steady state perfusion technique (triple-lumen tubing system) combined with simultaneous measurements of serum drug concentrations. Dissolved paracetamol was perfused over 160 min into different parts of the small intestine (65-210 cm beyond the teeth). Each of the four healthy subjects was studied twice with a proximal and a more distal site of perfusion. Serum drug concentrations were similar after proximal and distal perfusions. Mean drug absorption rates calculated from intestinal aspirate concentrations were similar in both parts of the intestine--proximal: 869 micrograms 30 cm-1 min-1 (95% CI: 659-1079) vs distal: 941 micrograms 30 cm-1 min-1 (794-1088). The absorption rate was related directly to the amount of paracetamol perfused per unit time as well as to the rate of transmucosal water fluxes. PMID:7917782

  1. [Study on lead absorption in pumpkin by atomic absorption spectrophotometry].

    PubMed

    Li, Zhen-Xia; Sun, Yong-Dong; Chen, Bi-Hua; Li, Xin-Zheng

    2008-07-01

    A study was carried out on the characteristic of lead absorption in pumpkin via atomic absorption spectrophotometer. The results showed that lead absorption amount in pumpkin increased with time, but the absorption rate decreased with time; And the lead absorption amount reached the peak in pH 7. Lead and cadmium have similar characteristic of absorption in pumpkin.

  2. Combustion chemistry and flame structure of furan group biofuels using molecular-beam mass spectrometry and gas chromatography - Part III: 2,5-Dimethylfuran.

    PubMed

    Togbé, Casimir; Tran, Luc-Sy; Liu, Dong; Felsmann, Daniel; Oßwald, Patrick; Glaude, Pierre-Alexandre; Sirjean, Baptiste; Fournet, René; Battin-Leclerc, Frédérique; Kohse-Höinghaus, Katharina

    2014-03-01

    This work is the third part of a study focusing on the combustion chemistry and flame structure of furan and selected alkylated derivatives, i.e. furan in Part I, 2-methylfuran (MF) in Part II, and 2,5-dimethylfuran (DMF) in the present work. Two premixed low-pressure (20 and 40 mbar) flat argon-diluted (50%) flames of DMF were studied with electron-ionization molecular-beam mass spectrometry (EI-MBMS) and gas chromatography (GC) under two equivalence ratios (φ=1.0 and 1.7). Mole fractions of reactants, products, and stable and radical intermediates were measured as a function of the distance to the burner. Kinetic modeling was performed using a reaction mechanism that was further developed in the present series, including Part I and Part II. A reasonable agreement between the present experimental results and the simulation is observed. The main reaction pathways of DMF consumption were derived from a reaction flow analysis. Also, a comparison of the key features for the three flames is presented, as well as a comparison between these flames of furanic compounds and those of other fuels. An a priori surprising ability of DMF to form soot precursors (e.g. 1,3-cyclopentadiene or benzene) compared to less substituted furans and to other fuels has been experimentally observed and is well explained in the model.

  3. Remote sensing of soot carbon - Part 2: Understanding the absorption Ångström exponent

    NASA Astrophysics Data System (ADS)

    Schuster, G. L.; Dubovik, O.; Arola, A.; Eck, T. F.; Holben, B. N.

    2016-02-01

    Recently, some authors have suggested that the absorption Ångström exponent (AAE) can be used to deduce the component aerosol absorption optical depths (AAODs) of carbonaceous aerosols in the AERONET database. This AAE approach presumes that AAE ≪ 1 for soot carbon, which contrasts the traditional small particle limit of AAE = 1 for soot carbon. Thus, we provide an overview of the AERONET retrieval, and we investigate how the microphysics of carbonaceous aerosols can be interpreted in the AERONET AAE product. We find that AAE ≪ 1 in the AERONET database requires large coarse mode fractions and/or imaginary refractive indices that increase with wavelength. Neither of these characteristics are consistent with the current definition of soot carbon, so we explore other possibilities for the cause of AAE ≪ 1. AAE is related to particle size, and coarse mode particles have a smaller AAE than fine mode particles for a given aerosol mixture of species. We also note that the mineral goethite has an imaginary refractive index that increases with wavelength, is very common in dust regions, and can easily contribute to AAE ≪ 1. We find that AAE ≪ 1 can not be caused by soot carbon, unless soot carbon has an imaginary refractive index that increases with wavelength throughout the visible and near-infrared spectrums. Finally, AAE is not a robust parameter for separating carbonaceous absorption from dust aerosol absorption in the AERONET database.

  4. Atmospheric absorption of terahertz radiation and water vapor continuum effects

    NASA Astrophysics Data System (ADS)

    Slocum, David M.; Slingerland, Elizabeth J.; Giles, Robert H.; Goyette, Thomas M.

    2013-09-01

    The water vapor continuum absorption spectrum was investigated using Fourier Transform Spectroscopy. The transmission of broadband terahertz radiation from 0.300 to 1.500 THz was recorded for multiple path lengths and relative humidity levels. The absorption coefficient as a function of frequency was determined and compared with theoretical predictions and available water vapor absorption data. The prediction code is able to separately model the different parts of atmospheric absorption for a range of experimental conditions. A variety of conditions were accurately modeled using this code including both self and foreign gas broadening for low and high water vapor pressures for many different measurement techniques. The intensity and location of the observed absorption lines were also in good agreement with spectral databases. However, there was a discrepancy between the resonant line spectrum simulation and the observed absorption spectrum in the atmospheric transmission windows caused by the continuum absorption. A small discrepancy remained even after using the best available data from the literature to account for the continuum absorption. From the experimental and resonant line simulation spectra the air-broadening continuum parameter was calculated and compared with values available in the literature.

  5. EFFECTS OF LASER RADIATION ON MATTER: Photoinduced absorption in chalcogenide glasses

    NASA Astrophysics Data System (ADS)

    Ponomar', V. V.

    1990-08-01

    A dependence of the absorption coefficient on the optical radiation intensity in the range 10 - 5 - 1 W/cm2 was observed for chalcogenide glasses at a photon energy less than the band gap of the material. The absorption coefficient depended on the irradiation time. In the case of arsenic sulfide in the range 1.6-1.7 eV an absorption peak was observed at intensities of the order of 10 - 3 W/cm2. In this part of the spectrum the absorption probably involved metastable As-As, S-Se, and Se-Se "defect" bonds and was similar to the photoinduced degradation of hydrogenated amorphous silicon.

  6. Determination of silicon in biomass and products of pyrolysis process via high-resolution continuum source atomic absorption spectrometry.

    PubMed

    Nakadi, Flávio V; Prodanov, Caroline; Boschetti, Wiliam; Vale, Maria Goreti R; Welz, Bernhard; de Andrade, Jailson B

    2018-03-01

    Thermochemical processes can convert the biomass into fuels, such as bio-oil. The biomass submitted to pyrolysis process, such as fibers, are generally rich in silicon, an element that can lead to damages in an engine when there is high concentration in a fuel. High-resolution continuum source atomic absorption spectrometry (HR-CS AAS) is an interesting alternative for Si determination in the products and byproducts of the pyrolysis process because, besides the flame (F) and graphite furnace (GF) atomizers, it has enhanced the application of direct analysis of solid samples (SS) within GF. This study aimed the development of methods to determine Si in biomass samples, their products and byproducts using HR-CS AAS. A high-resolution continuum source atomic absorption spectrometer contrAA 700 equipped with F and GF atomizers was used throughout the study. HR-CS F AAS (λ = 251.611nm, 1 detection pixel, N 2 O/C 2 H 2 flame) was used to evaluate Si content in biomass and ash, after a microwave-assisted acid digestion with HNO 3 and HF. HR-CS GF AAS (T pyr = 1400°C, T atom = 2650°C) has evaluated Si in pyrolysis water and bio-oil at 251.611nm, and in peach pit biomass and ash at 221.174nm using SS, both wavelengths with 1 detection pixel. Rhodium (300μg) was applied as permanent modifier and 10μgPd + 6μg Mg were pipetted onto the standards/samples at each analysis. Three different biomass samples were studied: palm tree fiber, coconut fiber and peach pit, and three certified reference materials (CRM) were used to verify the accuracy of the methods. The figures of merit were LOD 0.09-20mgkg -1 , and LOQ 0.3-20mgkg -1 , considering all the methods. There were no significant differences between the CRM certified values and the determined ones, using a Student t-test with a confidence interval of 95% (n = 5). Si concentration ranged from 0.11-0.92% mm -1 , 1.1-1.7mgkg -1 , 3.3-13mgkg -1 , and 0.41-1.4%mm -1 , in biomass, bio-oil, pyrolysis water and ash, respectively

  7. Fructo-oligosaccharides and calcium absorption and retention in adolescent girls.

    PubMed

    Martin, Berdine R; Braun, Michelle M; Wigertz, Karin; Bryant, Rebecca; Zhao, Yongdong; Lee, WangHee; Kempa-Steczko, Ania; Weaver, Connie M

    2010-08-01

    Several studies have shown a positive effect of fructo-oligosaccharides on calcium absorption and retention in animals and humans. Effects of levels of these pre-biotics that can be functionally incorporated into manufactured foods, have not been studied in controlled feeding studies. This study was designed to evaluate the effect of 9 g/d of fructo-oligosaccharides as part of a controlled diet on calcium absorption and retention in adolescent girls. Fourteen healthy adolescent girls aged 11-13 y were studied in a metabolic setting for two 3-week periods separated by a 2-week washout period. In a randomized, double-blinded, crossover design, the teens received a diet containing either 9 g/d oligofructose-enriched inulin in a calcium-fortified cereal or the control cereal with no inulin. Both diets contained ~1500 mg calcium daily. Calcium retention was determined on the third week of each period. On day 14 of the diet period, fractional calcium absorption was determined from the enrichment of (44)Ca in 4-day urine collections. Calcium absorption (67 ± 3 vs. 66 ± 3%) and retention (409 ± 394 vs. 464 ± 241 mg/d) were not significantly different when diets contained 9 g/d oligofructose-enriched inulin or not in a calcium-fortified cereal. Daily consumption of cereal containing a combination of short- and long-chain fructo-oligosaccharides as part of a controlled diet did not benefit calcium absorption or retention in adolescent girls. Lack of response to the prebiotic in this cohort may relate to their already high calcium absorption efficiency.

  8. Determination of trace amounts of tin in geological materials by atomic absorption spectrometry

    USGS Publications Warehouse

    Welsch, E.P.; Chao, T.T.

    1976-01-01

    An atomic absorption method is described for the determination of traces of tin in rocks, soils, and stream sediments. A dried mixture of the sample and ammonium iodide is heated to volatilize tin tetraiodide -which is then dissolved in 5 % hydrochloric acid, extracted into TOPO-MIBK, and aspirated into a nitrous oxide-acetylene flame. The limit of determination is 2 p.p.m. tin and the relative standard deviation ranges from 2 to 14 %. Up to 20 % iron and 1000 p.p.m. Cu, Pb, Zn, Mn, Hg, Mo, V, or W in the sample do not interfere. As many as 50 samples can be easily analyzed per man-day. ?? 1976.

  9. Counting Molecules by Desorption Ionization and Mass Spectrometry/Mass Spectrometry.

    ERIC Educational Resources Information Center

    Cooks, R. G.; Busch, K. L.

    1982-01-01

    Discusses two newer methods in mass spectrometry and shows how they can increase signal and signal-to-noise ratios, respectively. The first method, desorption ionization (DI), increases sensitivity while the second method, mass spectrometry/mass spectrometry (MS/MS), increases specificity. Together, the two methods offer improved analytical…

  10. Multivariate two-part statistics for analysis of correlated mass spectrometry data from multiple biological specimens.

    PubMed

    Taylor, Sandra L; Ruhaak, L Renee; Weiss, Robert H; Kelly, Karen; Kim, Kyoungmi

    2017-01-01

    High through-put mass spectrometry (MS) is now being used to profile small molecular compounds across multiple biological sample types from the same subjects with the goal of leveraging information across biospecimens. Multivariate statistical methods that combine information from all biospecimens could be more powerful than the usual univariate analyses. However, missing values are common in MS data and imputation can impact between-biospecimen correlation and multivariate analysis results. We propose two multivariate two-part statistics that accommodate missing values and combine data from all biospecimens to identify differentially regulated compounds. Statistical significance is determined using a multivariate permutation null distribution. Relative to univariate tests, the multivariate procedures detected more significant compounds in three biological datasets. In a simulation study, we showed that multi-biospecimen testing procedures were more powerful than single-biospecimen methods when compounds are differentially regulated in multiple biospecimens but univariate methods can be more powerful if compounds are differentially regulated in only one biospecimen. We provide R functions to implement and illustrate our method as supplementary information CONTACT: sltaylor@ucdavis.eduSupplementary information: Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  11. On-line separation and preconcentration of lead(II) by solid-phase extraction using activated carbon loaded with xylenol orange and its determination by flame atomic absorption spectrometry.

    PubMed

    Ensafi, Ali A; Shiraz, A Zendegi

    2008-02-11

    Activated carbon loaded with xylenol orange in a mini-column was used for the highly selective separation and preconcentration of Pb(II) ions. An on-line system for enrichment and the determination of Pb(II) was carried out on flame atomic absorption spectrometry. The conditions of preconcentration and quantitative recovery of Pb(II) from diluted solution, such as pH of aqueous phase, amount of the sorbent, volume of the solutions and flow variables were studied as well as effect of potential interfering ions. Under the optimum conditions, Pb(II) in an aqueous sample was concentrated about 200-fold and the detection limit was 0.4 ng mL(-1) Pb(II). The adsorption capacity of the solid phase was 0.20mg of lead per one gram of the modified activated carbon. The modified activated carbon is stable for several treatments of sample solutions without the need for using any chemical reagent. The recovery of lead(II) from river water, waste water, tap water, and in the following reference materials: SRM 2711 Montana soil and GBW-07605 tea were obtained in the range of 97-104% by the proposed method.

  12. Optical Measurement of Radiocarbon below Unity Fraction Modern by Linear Absorption Spectroscopy.

    PubMed

    Fleisher, Adam J; Long, David A; Liu, Qingnan; Gameson, Lyn; Hodges, Joseph T

    2017-09-21

    High-precision measurements of radiocarbon ( 14 C) near or below a fraction modern 14 C of 1 (F 14 C ≤ 1) are challenging and costly. An accurate, ultrasensitive linear absorption approach to detecting 14 C would provide a simple and robust benchtop alternative to off-site accelerator mass spectrometry facilities. Here we report the quantitative measurement of 14 C in gas-phase samples of CO 2 with F 14 C < 1 using cavity ring-down spectroscopy in the linear absorption regime. Repeated analysis of CO 2 derived from the combustion of either biogenic or petrogenic sources revealed a robust ability to differentiate samples with F 14 C < 1. With a combined uncertainty of 14 C/ 12 C = 130 fmol/mol (F 14 C = 0.11), initial performance of the calibration-free instrument is sufficient to investigate a variety of applications in radiocarbon measurement science including the study of biofuels and bioplastics, illicitly traded specimens, bomb dating, and atmospheric transport.

  13. Mass spectrometry with accelerators.

    PubMed

    Litherland, A E; Zhao, X-L; Kieser, W E

    2011-01-01

    As one in a series of articles on Canadian contributions to mass spectrometry, this review begins with an outline of the history of accelerator mass spectrometry (AMS), noting roles played by researchers at three Canadian AMS laboratories. After a description of the unique features of AMS, three examples, (14)C, (10)Be, and (129)I are given to illustrate the methods. The capabilities of mass spectrometry have been extended by the addition of atomic isobar selection, molecular isobar attenuation, further ion acceleration, followed by ion detection and ion identification at essentially zero dark current or ion flux. This has been accomplished by exploiting the techniques and accelerators of atomic and nuclear physics. In 1939, the first principles of AMS were established using a cyclotron. In 1977 the selection of isobars in the ion source was established when it was shown that the (14)N(-) ion was very unstable, or extremely difficult to create, making a tandem electrostatic accelerator highly suitable for assisting the mass spectrometric measurement of the rare long-lived radioactive isotope (14)C in the environment. This observation, together with the large attenuation of the molecular isobars (13)CH(-) and (12)CH 2(-) during tandem acceleration and the observed very low background contamination from the ion source, was found to facilitate the mass spectrometry of (14)C to at least a level of (14)C/C ~ 6 × 10(-16), the equivalent of a radiocarbon age of 60,000 years. Tandem Accelerator Mass Spectrometry, or AMS, has now made possible the accurate radiocarbon dating of milligram-sized carbon samples by ion counting as well as dating and tracing with many other long-lived radioactive isotopes such as (10)Be, (26)Al, (36)Cl, and (129)I. The difficulty of obtaining large anion currents with low electron affinities and the difficulties of isobar separation, especially for the heavier mass ions, has prompted the use of molecular anions and the search for alternative

  14. MULTIMAGNON ABSORPTION IN MNF2-OPTICAL ABSORPTION SPECTRUM.

    DTIC Science & Technology

    The absorption spectrum of MnF2 at 4.2K in the 3900A region was measured in zero external fields and in high fields. Exciton lines with magnon ...sidebands are observed, accompanied by a large number of weak satellite lines. Results on the exciton and magnon absorptions are similar to those of...McClure et al. The satellite lines are interpreted as being multi- magnon absorptions, and it is possible to fit the energy of all the absorptions with

  15. Iron species determination by task-specific ionic liquid-based in situ solvent formation dispersive liquid-liquid microextraction combined with flame atomic absorption spectrometry.

    PubMed

    Sadeghi, Susan; Ashoori, Vahid

    2017-10-01

    The task-specific ionic liquid (TSIL) of 1-ethyl-3-methylimidazolium bromide functionalized with 8-hydroxyquinoline was used as a chelating agent and extracting solvent for dispersive liquid-liquid microextraction and subsequent determination of Fe(III) by flame atomic absorption spectrometry. The in situ solvent formation of TSIL using KPF 6 provided the desired water-immiscible ionic liquid. The total Fe concentration could be determined after pre-oxidation of Fe(II) to Fe(III). Various factors affecting the proposed extraction procedure were optimized. The proposed analytical conditions were: sample pH 5, TSIL amount 0.3% (w/v), KPF 6 amount 0.15% (w/v), anti-sticking 0.1% (w/v) and salt concentration 5% (w/v). Under optimal conditions, the linear dynamic ranges for Fe(III) and total Fe were 20-80 and 20-110 ng mL -1 , respectively, with a detection limit of 6.9 ng mL -1 for Fe(III) and relative standard deviation of 2.2%. The proposed method was successfully applied to the determination of trace Fe(III) in water (underground, tap, refined water and artificial sea water) and beverage (apple, tomato, and tea) samples. The developed method offers advantages such as simplicity, ease of operation, and extraction of Fe(III) from aqueous solutions without the use of organic solvent. It was successfully applied for iron speciation in different real samples. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  16. Novel ion imprinted magnetic mesoporous silica for selective magnetic solid phase extraction of trace Cd followed by graphite furnace atomic absorption spectrometry detection

    NASA Astrophysics Data System (ADS)

    Zhao, Bingshan; He, Man; Chen, Beibei; Hu, Bin

    2015-05-01

    Determination of trace Cd in environmental, biological and food samples is of great significance to toxicological research and environmental pollution monitoring. While the direct determination of Cd in real-world samples is difficult due to its low concentration and the complex matrix. Herein, a novel Cd(II)-ion imprinted magnetic mesoporous silica (Cd(II)-II-MMS) was prepared and was employed as a selective magnetic solid-phase extraction (MSPE) material for extraction of trace Cd in real-world samples followed by graphite furnace atomic absorption spectrometry (GFAAS) detection. Under the optimized conditions, the detection limit of the proposed method was 6.1 ng L- 1 for Cd with the relative standard deviation (RSD) of 4.0% (c = 50 ng L- 1, n = 7), and the enrichment factor was 50-fold. To validate the proposed method, Certified Reference Materials of GSBZ 50009-88 environmental water, ZK018-1 lyophilized human urine and NIES10-b rice flour were analyzed and the determined values were in a good agreement with the certified values. The proposed method exhibited a robust anti-interference ability due to the good selectivity of Cd(II)-II-MMS toward Cd(II). It was successfully employed for the determination of trace Cd(II) in environmental water, human urine and rice samples with recoveries of 89.3-116%, demonstrating that the proposed method has good application potential in real world samples with complex matrix.

  17. Determination of macro and trace elements in multivitamin dietary supplements by high-resolution continuum source graphite furnace atomic absorption spectrometry with slurry sampling.

    PubMed

    Krawczyk, Magdalena

    2014-01-01

    In this research, three different commercially available multivitamin dietary supplements were analyzed by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS) with slurry sampling. The concentrations of Cr, Cu, Fe, Mn, and Se were determined and compared to the amounts stated by producers. The safety of multivitamin dietary supplements depends on various factors including the manufacturing process and the purity and origins of the raw ingredients. For this reason, this research determined concentrations of several toxic elements (As, Cd, and Pb). Microwave-assisted high pressure Teflon bomb digestion was used to determine total amounts of elements in samples. Samples were prepared as slurries at a concentration of 0.1% (m/v) for macro elements (Cr, Cu, Fe, Mn, and Se) and at a concentration of % (m/v) for trace elements (As, Cd, and Pb) in acidic media (3M HNO3). The influence of acid concentration, Triton X-100 addition, sonication time, and sonication power on absorbance was investigated. The accuracy of this method was validated by analyses of NRCC LUTS-1 (Lobster hepatopancreas), NRCC DORM-1 (Dogfish Muscle), NRCC DOLT-2 (Dogfish Liver), NBS SRM 1570 (Spinach Leaves) and NBS SRM 1573 (Tomato Leaves) certified reference materials. The measured elements contents in these reference materials (except NRCC DOLT-2) were in satisfactory agreement with the certified values according to the t-test for a 95% confidence level. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. MASS SPECTROMETRY OF FATTY ALDEHYDES

    PubMed Central

    Berdyshev, Evgeny V.

    2011-01-01

    Fatty aldehydes are important components of the cellular lipidome. Significant interest has been developed towards the analysis of the short chain α,β-unsaturated and hydroxylated aldehydes formed as a result of oxidation of polyunsaturated fatty acids. Multiple gas chromatography-mass spectrometry (GC/MS) and subsequently liquid chromatography-mass spectrometry (LC/MS) approaches have been developed to identify and quantify short-chain as well as long-chain fatty aldehydes. Due to the ability to non-enzymaticaly form Schiff bases with amino groups of proteins, lipids, and with DNA guanidine, free aldehydes are viewed as a marker or metric of fatty acid oxidation and not the part of intracellular signaling pathways which has significantly limited the overall attention this group of molecules have received. This review provides an overview of current GC/MS and LC/MS approaches of fatty aldehyde analysis as well as discusses technical challenges standing in the way of free fatty aldehyde quantitation. PMID:21930240

  19. [Determination of the content of sulfur of coal by the infrared absorption method with high acccuracy].

    PubMed

    Wang, Hai-Feng; Lu, Hai; Li, Jia; Sun, Guo-Hua; Wang, Jun; Dai, Xin-Hua

    2014-02-01

    The present paper reported the differential scanning calorimetry-thermogravimetry curves and the infrared (IR) absorption spectrometry under the temperature program analyzed by the combined simultaneous thermal analysis-IR spectrometer. The gas products of coal were identified by the IR spectrometry. This paper emphasized on the combustion at high temperature-IR absorption method, a convenient and accurate method, which measures the content of sulfur in coal indirectly through the determination of the content of sulfur dioxide in the mixed gas products by IR absorption. It was demonstrated, when the instrument was calibrated by varied pure compounds containing sulfur and certified reference materials (CRMs) for coal, that there was a large deviation in the measured sulfur contents. It indicates that the difference in chemical speciations of sulfur between CRMs and the analyte results in a systematic error. The time-IR absorption curve was utilized to analyze the composition of sulfur at low temperatures and high temperatures and then the sulfur content of coal sample was determined by using a CRM for coal with a close composition of sulfur. Therefore, the systematic error due to the difference in chemical speciations of sulfur between the CRM and analyte was eliminated. On the other hand, in this combustion at high temperature-IR absorption method, the mass of CRM and analyte were adjusted to assure the sulfur mass equal and then the CRM and the analyte were measured alternately. This single-point calibration method reduced the effect of the drift of the IR detector and improved the repeatability of results, compared with the conventional multi-point calibration method using the calibration curves of signal intensity vs sulfur mass. The sulfur content results and their standard deviations of an anthracite coal and a bituminous coal with a low sulfur content determined by this modified method were 0.345% (0.004%) and 0.372% (0.008%), respectively. The uncertainty (U

  20. Soft X-ray Absorption Edges in LMXBs

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The XMM observation of LMC X-2 is part of our program to study X-ray absorption in the interstellar medium (ISM). This program includes a variety of bright X-ray binaries in the Galaxy as well as the Magellanic Clouds (LMC and SMC). LMC X-2 is located near the heart of the LMC. Its very soft X-ray spectrum is used to determine abundance and ionization fractions of neutral and lowly ionized oxygen of the ISM in the LMC. The RGS spectrum so far allowed us to determine the O-edge value to be for atomic O, the EW of O-I in the ls-2p resonance absorption line, and the same for O-II. The current study is still ongoing in conjunction with other low absorption sources like Sco X-1 and the recently observed X-ray binary 4U 1957+11.

  1. Through a Glass Darkly: Glimpses into the Future of Mass Spectrometry

    PubMed Central

    Cooks, R. Graham; Mueller, Thomas

    2013-01-01

    The paper has three parts, (i) a brief overview of the main achievements made using mass spectrometry across all the fields of science, (ii) a survey of some of the topics currently being pursued most activity, including both applications and fundamental studies, and (iii) some hints as to what the future of mass spectrometry might hold with particular emphasis on revolutionary changes in the subject. Emphasis is given to ambient methods of ionization and their use in disease diagnosis and to their use in combination with miniature mass spectrometers for in-situ measurements. Special attention goes to the chemical aspects of mass spectrometry, including its emerging role as a preparative method based on accelerated bimolecular reaction rates in solution and on ion soft landing as a means of surface tailoring. In summary, the paper covers the proud history, vibrant present and expansive future of mass spectrometry. PMID:24349920

  2. Major roles for minor bacterial lipids identified by mass spectrometry.

    PubMed

    Garrett, Teresa A

    2017-11-01

    Mass spectrometry of lipids, especially those isolated from bacteria, has ballooned over the past two decades, affirming in the process the complexity of the lipidome. With this has come the identification of new and interesting lipid structures. Here is an overview of several novel lipids, from both Gram-negative and Gram-positive bacteria with roles in health and disease, whose structural identification was facilitated using mass spectrometry. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Combustion chemistry and flame structure of furan group biofuels using molecular-beam mass spectrometry and gas chromatography – Part II: 2-Methylfuran

    PubMed Central

    Tran, Luc-Sy; Togbé, Casimir; Liu, Dong; Felsmann, Daniel; Oßwald, Patrick; Glaude, Pierre-Alexandre; Fournet, René; Sirjean, Baptiste; Battin-Leclerc, Frédérique; Kohse-Höinghaus, Katharina

    2013-01-01

    This is Part II of a series of three papers which jointly address the combustion chemistry of furan and its alkylated derivatives 2-methylfuran (MF) and 2,5-dimethylfuran (DMF) under premixed low-pressure flame conditions. Some of them are considered to be promising biofuels. With furan as a common basis studied in Part I of this series, the present paper addresses two laminar premixed low-pressure (20 and 40 mbar) flat argon-diluted (50%) flames of MF which were studied with electron-ionization molecular-beam mass spectrometry (EI-MBMS) and gas chromatography (GC) for equivalence ratios φ=1.0 and 1.7, identical conditions to those for the previously reported furan flames. Mole fractions of reactants, products as well as stable and reactive intermediates were measured as a function of the distance above the burner. Kinetic modeling was performed using a comprehensive reaction mechanism for all three fuels given in Part I and described in the three parts of this series. A comparison of the experimental results and the simulation shows reasonable agreement, as also seen for the furan flames in Part I before. This set of experiments is thus considered to be a valuable additional basis for the validation of the model. The main reaction pathways of MF consumption have been derived from reaction flow analyses, and differences to furan combustion chemistry under the same conditions are discussed. PMID:24518895

  4. Diamond nanowires for highly sensitive matrix-free mass spectrometry analysis of small molecules.

    PubMed

    Coffinier, Yannick; Szunerits, Sabine; Drobecq, Hervé; Melnyk, Oleg; Boukherroub, Rabah

    2012-01-07

    This paper reports on the use of boron-doped diamond nanowires (BDD NWs) as an inorganic substrate for matrix-free laser desorption/ionization mass spectrometry (LDI-MS) analysis of small molecules. The diamond nanowires are prepared by reactive ion etching (RIE) with oxygen plasma of highly boron-doped (the boron level is 10(19) B cm(-3)) or undoped nanocrystalline diamond substrates. The resulting diamond nanowires are coated with a thin silicon oxide layer that confers a superhydrophilic character to the surface. To minimize droplet spreading, the nanowires were chemically functionalized with octadecyltrichlorosilane (OTS) and then UV/ozone treated to reach a final water contact angle of 120°. The sub-bandgap absorption under UV laser irradiation and the heat confinement inside the nanowires allowed desorption/ionization, most likely via a thermal mechanism, and mass spectrometry analysis of small molecules. A detection limit of 200 zeptomole for verapamil was demonstrated.

  5. Combustion chemistry and flame structure of furan group biofuels using molecular-beam mass spectrometry and gas chromatography – Part III: 2,5-Dimethylfuran

    PubMed Central

    Togbé, Casimir; Tran, Luc-Sy; Liu, Dong; Felsmann, Daniel; Oßwald, Patrick; Glaude, Pierre-Alexandre; Sirjean, Baptiste; Fournet, René; Battin-Leclerc, Frédérique; Kohse-Höinghaus, Katharina

    2013-01-01

    This work is the third part of a study focusing on the combustion chemistry and flame structure of furan and selected alkylated derivatives, i.e. furan in Part I, 2-methylfuran (MF) in Part II, and 2,5-dimethylfuran (DMF) in the present work. Two premixed low-pressure (20 and 40 mbar) flat argon-diluted (50%) flames of DMF were studied with electron-ionization molecular-beam mass spectrometry (EI-MBMS) and gas chromatography (GC) under two equivalence ratios (φ=1.0 and 1.7). Mole fractions of reactants, products, and stable and radical intermediates were measured as a function of the distance to the burner. Kinetic modeling was performed using a reaction mechanism that was further developed in the present series, including Part I and Part II. A reasonable agreement between the present experimental results and the simulation is observed. The main reaction pathways of DMF consumption were derived from a reaction flow analysis. Also, a comparison of the key features for the three flames is presented, as well as a comparison between these flames of furanic compounds and those of other fuels. An a priori surprising ability of DMF to form soot precursors (e.g. 1,3-cyclopentadiene or benzene) compared to less substituted furans and to other fuels has been experimentally observed and is well explained in the model. PMID:24518851

  6. Coal thickness gauge using RRAS techniques, part 1. [radiofrequency resonance absorption

    NASA Technical Reports Server (NTRS)

    Rollwitz, W. L.; King, J. D.

    1978-01-01

    A noncontacting sensor having a measurement range of 0 to 6 in or more, and with an accuracy of 0.5 in or better is needed to control the machinery used in modern coal mining so that the thickness of the coal layer remaining over the rock is maintained within selected bounds. The feasibility of using the radiofrequency resonance absorption (RRAS) techniques of electron magnetic resonance (EMR) and nuclear magnetic resonance (NMR) as the basis of a coal thickness gauge is discussed. The EMR technique was found, by analysis and experiments, to be well suited for this application.

  7. Isolated human/animal stratum corneum as a partial model for 15 steps in percutaneous absorption: emphasizing decontamination, Part I.

    PubMed

    Hui, Xiaoying; Lamel, Sonia; Qiao, Peter; Maibach, Howard I

    2013-03-01

    Since the advent of World War II, governments and laboratories have made a concerted effort to improve prophylactic and therapeutic interventions counteracting cutaneously directed chemical warfare agents (CWA), and by inference, common industrial and consumer dermatotoxicants. In vitro percutaneous penetration assays, first utilized by Tregear in the 1940s and presently in various modifications, have been fundamental to this effort. Percutaneous penetration, often considered a simple one-step diffusion process, consists of at least 15 steps. The first part of this review covers the initial steps related to absorption and excretion kinetics, vehicle characteristics, and tissue disposition. Importantly, the partitioning behavior and stratum corneum (SC) diffusion by a wide physicochemical array of compounds shows that many compounds have similar diffusion coefficients determining their percutaneous absorption in vivo. After accounting for anatomical SC variation, the penetration flux value of a substance depends mainly on its SC/vehicle partition coefficient. Additionally, the SC acts as a 'reservoir' for topically applied molecules and application of tape stripping has been found to quantify the chemical remaining in the SC which can predict total molecular penetration in vivo. Decontamination is of particular concern and even expediting standard washing procedures after dermal chemical exposure often fails to remove chemicals. This overview summarizes knowledge of percutaneous penetration extending insights into the complexities of penetration, decontamination and potential newer assays that may be of practical importance. Copyright © 2012 John Wiley & Sons, Ltd.

  8. The Role of Naturally Occurring Stable Isotopes in Mass Spectrometry, Part II: The Instrumentation

    PubMed Central

    Bluck, Les; Volmer, Dietrich A.

    2013-01-01

    In the second instalment of this tutorial, the authors explain the instrumentation for measuring naturally occurring stable isotopes, specifically the magnetic sector mass spectrometer. This type of instrument remains unrivalled in its performance for isotope ratio mass spectrometry (IRMS) and the reader is reminded of its operation and its technical advantages for isotope measurements. PMID:23772101

  9. Quantitative aspects of inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Bulska, Ewa; Wagner, Barbara

    2016-10-01

    Accurate determination of elements in various kinds of samples is essential for many areas, including environmental science, medicine, as well as industry. Inductively coupled plasma mass spectrometry (ICP-MS) is a powerful tool enabling multi-elemental analysis of numerous matrices with high sensitivity and good precision. Various calibration approaches can be used to perform accurate quantitative measurements by ICP-MS. They include the use of pure standards, matrix-matched standards, or relevant certified reference materials, assuring traceability of the reported results. This review critically evaluates the advantages and limitations of different calibration approaches, which are used in quantitative analyses by ICP-MS. Examples of such analyses are provided. This article is part of the themed issue 'Quantitative mass spectrometry'.

  10. A green and efficient procedure for the preconcentration and determination of cadmium, nickel and zinc from freshwater, hemodialysis solutions and tuna fish samples by cloud point extraction and flame atomic absorption spectrometry.

    PubMed

    Galbeiro, Rafaela; Garcia, Samara; Gaubeur, Ivanise

    2014-04-01

    Cloud point extraction (CPE) was used to simultaneously preconcentrate trace-level cadmium, nickel and zinc for determination by flame atomic absorption spectrometry (FAAS). 1-(2-Pyridilazo)-2-naphthol (PAN) was used as a complexing agent, and the metal complexes were extracted from the aqueous phase by the surfactant Triton X-114 ((1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol). Under optimized complexation and extraction conditions, the limits of detection were 0.37μgL(-1) (Cd), 2.6μgL(-1) (Ni) and 2.3μgL(-1) (Zn). This extraction was quantitative with a preconcentration factor of 30 and enrichment factor estimated to be 42, 40 and 43, respectively. The method was applied to different complex samples, and the accuracy was evaluated by analyzing a water standard reference material (NIST SRM 1643e), yielding results in agreement with the certified values. Copyright © 2013 Elsevier GmbH. All rights reserved.

  11. Separation and Enrichment of Gold in Water, Geological and Environmental Samples by Solid Phase Extraction on Multiwalled Carbon Nanotubes Prior to its Determination by Flame Atomic Absorption Spectrometry.

    PubMed

    Duran, Ali; Tuzen, Mustafa; Soylak, Mustafa

    2015-01-01

    This study proposes the application of multi-walled carbon nanotubes as a solid sorbent for the preconcentration of gold prior to its flame atomic absorption spectrometry determination. Extraction was achieved by using a glass column (15.0 cm in length and 1.0 cm in diameter). Quantitative recoveries were obtained in the pH range of 2.5-4.0; the elution step was carried out with 5.0 ml of 1.0 mol/L HNO3 in acetone. In the ligand-free study, variables such as pH, eluent type, sample volume, flow rates, and matrix effect were examined for the optimum recovery of gold ions. The gold ions were able to be pre-concentrated by a factor of 150 and their LOD was determined to be 1.71 μg/L. In order to evaluate the accuracy of the developed method, addition-recovery tests were applied for the tap water, mineral water, and sea water samples. Gold recovery studies were implemented using a wet digestion technique for mine and soil samples taken from various media, and this method was also applied for anodic slime samples taken from the factories located in the Kayseri Industrial Zone of Turkey.

  12. Preparation of modified magnetic nanoparticles as a sorbent for the preconcentration and determination of cadmium ions in food and environmental water samples prior to flame atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Mirabi, Ali; Dalirandeh, Zeinab; Rad, Ali Shokuhi

    2015-05-01

    A new method has been developed for the separation/preconcentration of trace level cadmium ions using diphenyl carbazone/sodium dodecyl sulfate immobilized on magnetic nanoparticle Fe3O4 as a new sorbent SPE and their determination by flame atomic absorption spectrometry (FAAS). Synthesized nanoparticle was characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM). Various influencing parameters on the separation and preconcentration of trace level cadmium ions such as, pH value, amount of nanoparticles, amount of diphenyl carbazone, condition of eluting solution, the effects of matrix ions were examined. The cadmium ions can be eluted from the modified magnetic nanoparticle using 1 mol L-1 HCl as a desorption reagent. The detection limit of this method for cadmium was 3.71 ng ml-1 and the R.S.D. was 0.503% (n=6). The advantages of this new method include rapidity, easy preparation of sorbents and a high concentration factor. The proposed method has been applied to the determination of Cd ions at trace levels in real samples such as, green tea, rice, tobacco, carrot, lettuce, ginseng, spice, tap water, river water, sea water with satisfactory results.

  13. Restricted access carbon nanotubes for direct extraction of cadmium from human serum samples followed by atomic absorption spectrometry analysis.

    PubMed

    Barbosa, Adriano F; Barbosa, Valéria M P; Bettini, Jefferson; Luccas, Pedro O; Figueiredo, Eduardo C

    2015-01-01

    In this paper, we propose a new sorbent that is able to extract metal ions directly from untreated biological fluids, simultaneously excluding all proteins from these samples. The sorbent was obtained through the modification of carbon nanotubes (CNTs) with an external bovine serum albumin (BSA) layer, resulting in restricted access carbon nanotubes (RACNTs). The BSA layer was fixed through the interconnection between the amine groups of the BSA using glutaraldehyde as cross-linker. When a protein sample is percolated through a cartridge containing RACNTs and the sample pH is higher than the isoelectric point of the proteins, both proteins from the sample and the BSA layer are negatively ionized. Thus, an electrostatic repulsion prevents the interaction between the proteins from the sample on the RACNTs surface. At the same time, metal ions are adsorbed in the CNTs (core) after their passage through the chains of proteins. The Cd(2+) ion was selected for a proof-of-principle case to test the suitability of the RACNTs due to its toxicological relevance. RACNTs were able to extract Cd(2+) and exclude almost 100% of the proteins from the human serum samples in an online solid-phase extraction system coupled with thermospray flame furnace atomic absorption spectrometry. The limits of detection and quantification were 0.24 and 0.80 μg L(-1), respectively. The sampling frequency was 8.6h(-1), and the intra- and inter-day precisions at the 0.80, 15.0, and 30.0 μg L(-1) Cd(2+) levels were all lower than 10.1% (RSD). The recoveries obtained for human blood serum samples fortified with Cd(2+) ranged from 85.0% to 112.0%. The method was successfully applied to analyze Cd(2+) directly from six human blood serum samples without any pretreatment, and the observed concentrations ranged from

  14. Determination of Ultra-trace Rhodium in Water Samples by Graphite Furnace Atomic Absorption Spectrometry after Cloud Point Extraction Using 2-(5-Iodo-2-Pyridylazo)-5-Dimethylaminoaniline as a Chelating Agent.

    PubMed

    Han, Quan; Huo, Yanyan; Wu, Jiangyan; He, Yaping; Yang, Xiaohui; Yang, Longhu

    2017-03-24

    A highly sensitive method based on cloud point extraction (CPE) separation/preconcentration and graphite furnace atomic absorption spectrometry (GFAAS) detection has been developed for the determination of ultra-trace amounts of rhodium in water samples. A new reagent, 2-(5-iodo-2-pyridylazo)-5-dimethylaminoaniline (5-I-PADMA), was used as the chelating agent and the nonionic surfactant TritonX-114 was chosen as extractant. In a HAc-NaAc buffer solution at pH 5.5, Rh(III) reacts with 5-I-PADMA to form a stable chelate by heating in a boiling water bath for 10 min. Subsequently, the chelate is extracted into the surfactant phase and separated from bulk water. The factors affecting CPE were investigated. Under the optimized conditions, the calibration graph was linear in the range of 0.1-6.0 ng/mL, the detection limit was 0.023 ng/mL for rhodium and relative standard deviation was 3.67% ( c = 1.0 ng/mL, n = 11).The method has been applied to the determination of trace rhodium in water samples with satisfactory results.

  15. In situ flow cell for combined X-ray absorption spectroscopy, X-ray diffraction, and mass spectrometry at high photon energies under solar thermochemical looping conditions

    NASA Astrophysics Data System (ADS)

    Rothensteiner, Matthäus; Jenni, Joel; Emerich, Hermann; Bonk, Alexander; Vogt, Ulrich F.; van Bokhoven, Jeroen A.

    2017-08-01

    An in situ/operando flow cell for transmission mode X-ray absorption spectroscopy (XAS), X-ray diffraction (XRD), and combined XAS/XRD measurements in a single experiment under the extreme conditions of two-step solar thermochemical looping for the dissociation of water and/or carbon dioxide was developed. The apparatus exposes materials to relevant conditions of both the auto-reduction and the oxidation sub-steps of the thermochemical cycle at ambient temperature up to 1773 K and enables determination of the composition of the effluent gases by online quadrupole mass spectrometry. The cell is based on a tube-in-tube design and is heated by means of a focusing infrared furnace. It was tested successfully for carbon dioxide splitting. In combined XAS/XRD experiments with an unfocused beam, XAS measurements were performed at the Ce K edge (40.4 keV) and XRD measurements at 64.8 keV and 55.9 keV. Furthermore, XRD measurements with a focused beam at 41.5 keV were carried out. Equimolar ceria-hafnia was auto-reduced in a flow of argon and chemically reduced in a flow of hydrogen/helium. Under reducing conditions, all cerium(iv) was converted to cerium(iii) and a cation-ordered pyrochlore-type structure was formed, which was not stable upon oxidation in a flow of carbon dioxide.

  16. In situ flow cell for combined X-ray absorption spectroscopy, X-ray diffraction, and mass spectrometry at high photon energies under solar thermochemical looping conditions.

    PubMed

    Rothensteiner, Matthäus; Jenni, Joel; Emerich, Hermann; Bonk, Alexander; Vogt, Ulrich F; van Bokhoven, Jeroen A

    2017-08-01

    An in situ/operando flow cell for transmission mode X-ray absorption spectroscopy (XAS), X-ray diffraction (XRD), and combined XAS/XRD measurements in a single experiment under the extreme conditions of two-step solar thermochemical looping for the dissociation of water and/or carbon dioxide was developed. The apparatus exposes materials to relevant conditions of both the auto-reduction and the oxidation sub-steps of the thermochemical cycle at ambient temperature up to 1773 K and enables determination of the composition of the effluent gases by online quadrupole mass spectrometry. The cell is based on a tube-in-tube design and is heated by means of a focusing infrared furnace. It was tested successfully for carbon dioxide splitting. In combined XAS/XRD experiments with an unfocused beam, XAS measurements were performed at the Ce K edge (40.4 keV) and XRD measurements at 64.8 keV and 55.9 keV. Furthermore, XRD measurements with a focused beam at 41.5 keV were carried out. Equimolar ceria-hafnia was auto-reduced in a flow of argon and chemically reduced in a flow of hydrogen/helium. Under reducing conditions, all cerium(iv) was converted to cerium(iii) and a cation-ordered pyrochlore-type structure was formed, which was not stable upon oxidation in a flow of carbon dioxide.

  17. Pressure Measurements Using an Airborne Differential Absorption Lidar. Part 1; Analysis of the Systematic Error Sources

    NASA Technical Reports Server (NTRS)

    Flamant, Cyrille N.; Schwemmer, Geary K.; Korb, C. Laurence; Evans, Keith D.; Palm, Stephen P.

    1999-01-01

    Remote airborne measurements of the vertical and horizontal structure of the atmospheric pressure field in the lower troposphere are made with an oxygen differential absorption lidar (DIAL). A detailed analysis of this measurement technique is provided which includes corrections for imprecise knowledge of the detector background level, the oxygen absorption fine parameters, and variations in the laser output energy. In addition, we analyze other possible sources of systematic errors including spectral effects related to aerosol and molecular scattering interference by rotational Raman scattering and interference by isotopic oxygen fines.

  18. Part-body and multibody effects on absorption of radio-frequency electromagnetic energy by animals and by models of man

    NASA Technical Reports Server (NTRS)

    Gandhi, O. P.; Hagmann, M. J.; Dandrea, J. A.

    1979-01-01

    Fine structure in the whole-body resonant curve for radio-frequency energy deposition in man can be attributed to part-body resonances. As for head resonance, which occurs near 350 MHz in man, the absorptive cross section is nearly three times the physical cross section of the head. The arm has a prominent resonance at 150 MHz. Numerical solutions, antenna theory, and experimental results on animals have shown that whole-body energy deposition may be increased by 50 percent or more because of multiple bodies that are strategically located in the field. Empirical equations for SARs are also presented along with test data for several species of laboratory animals. Barbiturate anesthesia is sufficiently disruptive of thermoregulation that delta Ts of colonic temperature yield energy dose values in several mammals that compare quite favorably with those based on whole-body calorimetry.

  19. Absence of food effect on the extent of alprazolam absorption from an orally disintegrating tablet.

    PubMed

    Erdman, Keith; Stypinski, Daria; Combs, Michelle; Witt, Patricia; Stiles, Mark; Pollock, Steve

    2007-08-01

    To evaluate the effect of a standardized meal on the bioavailability of alprazolam formulated as an immediate-release orally disintegrating tablet (ODT) in healthy volunteers. Single-dose, randomized, open-label, two-period crossover study. Contract research organization clinic. Sixteen healthy volunteers (seven men, nine women), aged 20-50 years. Intervention. Subjects were administered a single dose of alprazolam ODT 1.0 mg during two treatment periods-under fasting conditions and after a standard high-fat breakfast-separated by a 7-day washout period, Blood samples for determination of alprazolam pharmacokinetics were collected by venipuncture up to 72 hours after dosing. A validated liquid chromatography with tandem mass spectrometry detection method was used to quantify the alprazolam plasma concentration. The overall extent of alprazolam absorption from the ODT formulation, as measured by area under the concentration-time curve, was unaffected during fed conditions. However, the rate of alprazolam absorption was slower after administration during fed relative to fasted conditions. The mean maximum observed plasma concentration (Cmax) decreased approximately 25%, and time to Cmax (Tmax) was delayed approximately 1.5 hours when food was administered before dosing. Coadministration of food was shown to have no effect on extent of absorption of immediate-release alprazolam ODT 1.0 mg when compared with drug administration in the fasted condition; however, the rate of drug absorption was decreased. The clinical significance of the difference in rate of alprazolam absorption is unknown but thought to be minimal.

  20. Deciphering Dorin M glycosylation by mass spectrometry.

    PubMed

    Man, Petr; Kovár, Vojtech; Sterba, Ján; Strohalm, Martin; Kavan, Daniel; Kopácek, Petr; Grubhoffer, Libor; Havlícek, Vladimír

    2008-01-01

    The soft tick, Ornithodoros moubata, is a vector of several bacterial and viral pathogens including Borrelia duttoni, a causative agent of relapsing fever and African swine fever virus. Previously, a sialic acid-specific lectin Dorin M was isolated from its hemolymph. Here, we report on the complete characterization of the primary sequence of Dorin M. Using liquid chromatography coupled to mass spectrometry, we identified three different glycopeptides in the tryptic digest of Dorin M. The peptide, as well as the glycan part of all glycopeptides, were further fully sequenced by means of tandem mass spectrometry (MS2) and multiple-stage mass spectrometry (MS3). Two classical N-glycosylation sites were modified by high-mannose-type glycans containing up to nine mannose residues. The third site bore a glycan with four to five mannose residues and a deoxyhexose (fucose) attached to the proximal N-acetylglycosamine. The microheterogeneity at each site was estimated based on chromatographic behavior of different glycoforms. The fourth, a non-classical N-glycosylation site (Asn-Asn-Cys), was not glycosylated, probably due to the involvement of the cysteine residue in a disulfide bridge.

  1. Enhanced broadband absorption in nanowire arrays with integrated Bragg reflectors

    NASA Astrophysics Data System (ADS)

    Aghaeipour, Mahtab; Pettersson, Håkan

    2018-05-01

    A near-unity unselective absorption spectrum is desirable for high-performance photovoltaics. Nanowire (NW) arrays are promising candidates for efficient solar cells due to nanophotonic absorption resonances in the solar spectrum. The absorption spectra, however, display undesired dips between the resonance peaks. To achieve improved unselective broadband absorption, we propose to enclose distributed Bragg reflectors (DBRs) in the bottom and top parts of indium phosphide (InP) NWs, respectively. We theoretically show that by enclosing only two periods of In0.56Ga0.44As/InP DBRs, an unselective 78% absorption efficiency (72% for NWs without DBRs) is obtained at normal incidence in the spectral range from 300 nm to 920 nm. Under oblique light incidence, the absorption efficiency is enhanced up to about 85% at an incidence angle of 50°. By increasing the number of DBR periods from two to five, the absorption efficiency is further enhanced up to 95% at normal incidence. In this work, we calculated optical spectra for InP NWs, but the results are expected to be valid for other direct band gap III-V semiconductor materials. We believe that our proposed idea of integrating DBRs in NWs offers great potential for high-performance photovoltaic applications.

  2. Use of radiation sources with mercury isotopes for real-time highly sensitive and selective benzene determination in air and natural gas by differential absorption spectrometry with the direct Zeeman effect.

    PubMed

    Revalde, Gita; Sholupov, Sergey; Ganeev, Alexander; Pogarev, Sergey; Ryzhov, Vladimir; Skudra, Atis

    2015-08-05

    A new analytical portable system is proposed for the direct determination of benzene vapor in the ambient air and natural gas, using differential absorption spectrometry with the direct Zeeman effect and innovative radiation sources: capillary mercury lamps with different isotopic compositions ((196)Hg, (198)Hg, (202)Hg, (204)Hg, and natural isotopic mixture). Resonance emission of mercury at a wavelength of 254 nm is used as probing radiation. The differential cross section of benzene absorption in dependence on wavelength is determined by scanning of magnetic field. It is found that the sensitivity of benzene detection is enhanced three times using lamp with the mercury isotope (204)Hg in comparison with lamp, filled with the natural isotopic mixture. It is experimentally demonstrated that, when benzene content is measured at the Occupational Exposure Limit (3.2 mg/m(3) for benzene) level, the interference from SO2, NO2, O3, H2S and toluene can be neglected if concentration of these gases does not exceed corresponding Occupational Exposure Limits. To exclude the mercury effect, filters that absorb mercury and let benzene pass in the gas duct are proposed. Basing on the results of our study, a portable spectrometer is designed with a multipath cell of 960 cm total path length and detection limit 0.5 mg/m(3) at 1 s averaging and 0.1 mg/m(3) at 30 s averaging. The applications of the designed spectrometer to measuring the benzene concentration in the atmospheric air from a moving vehicle and in natural gas are exemplified. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Trends in tungsten coil atomic spectrometry

    NASA Astrophysics Data System (ADS)

    Donati, George L.

    Renewed interest in electrothermal atomic spectrometric methods based on tungsten coil atomizers is a consequence of a world wide increasing demand for fast, inexpensive, sensitive, and portable analytical methods for trace analysis. In this work, tungsten coil atomic absorption spectrometry (WCAAS) and tungsten coil atomic emission spectrometry (WCAES) are used to determine several different metals and even a non-metal at low levels in different samples. Improvements in instrumentation and new strategies to reduce matrix effects and background signals are presented. Investigation of the main factors affecting both WCAAS and WCAES analytical signals points to the importance of a reducing, high temperature gas phase in the processes leading to atomic cloud generation. Some more refractory elements such as V and Ti were determined for the first time by double tungsten coil atomic emission spectrometry (DWCAES). The higher temperatures provided by two atomizers in DWCAES also allowed the detection of Ag, Cu and Sn emission signals for the first time. Simultaneous determination of several elements by WCAES in relatively complex sample matrices was possible after a simple acid extraction. The results show the potential of this method as an alternative to more traditional, expensive methods for fast, more effective analyses and applications in the field. The development of a new metallic atomization cell is also presented. Lower limits of detection in both WCAAS and WCAES determinations were obtained due to factors such as better control of background signal, smaller, more isothermal system, with atomic cloud concentration at the optical path for a longer period of time. Tungsten coil-based methods are especially well suited to applications requiring low sample volume, low cost, sensitivity and portability. Both WCAAS and WCAES have great commercial potential in fields as diverse as archeology and industrial quality control. They are simple, inexpensive, effective

  4. Mineral and Lithology Mapping of Drill Core Pulps Using Visible and Infrared Spectrometry

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Taylor, G. R., E-mail: G.Taylor@unsw.edu.au

    2000-12-15

    A novel approach for using field spectrometry for determining both the mineralogy and the lithology of drill core pulps (powders) is developed and evaluated. The methodology is developed using material from a single drillhole through a mineralized sequence of rocks from central New South Wales. Mineral library spectra are used in linear unmixing routines to determine the mineral abundances in drill core pulps that represent between 1 m and 3 m of core. Comparison with X-Ray Diffraction (XRD) analyses shows that for most major constituents, spectrometry provides an estimate of quantitative mineralogy that is as reliable as that provided bymore » XRD. Confusion between the absorption features of calcite and those of chlorite causes the calcite contents determined by spectrometry to be unreliable. Convex geometry is used to recognize the spectra of those samples that are extreme and are representative of unique lithologies. Linear unmixing is used to determine the abundance of these lithologies in each drillhole sample and these abundances are used to interpret the geology of the drillhole. The interpreted geology agrees well with conventional drillhole logs of the visible geology and photographs of the split core. The methods developed provide a quick and cost-effective way of determining the lithology and alteration mineralogy of drill core pulps.« less

  5. A preconcentration method for indirect determination of acrylamide from chips, crackers and cereal-based baby foods using flame atomic absorption spectrometry.

    PubMed

    Altunay, Nail; Gürkan, Ramazan; Orhan, Ulaş

    2016-12-01

    Acrylamide is a toxic species for human health, and is a Maillard reaction product which forms spontaneously in heat treatment process of foods. Therefore, a simple, fast and cost-effective method was developed for the indirect determination of acrylamide in processed foods particularly consumed by children. The method is based on ion-pairing of acrylamide with fluorescein (F 2- ) in presence of Ni(II) ions at pH 9.0, and then extraction of the formed ternary complex into micellar phase of poly(ethyleneglycol-mono-p-nonylphenylether) (PONPE 7.5) before analysis by flame atomic absorption spectrometry (FAAS). The ultrasonic-assisted cloud point extraction (UA-CPE) has been used for the preconcentration of acrylamide in the samples prior to its FAAS detection. The matrix matched calibration curve is linear in range of 0.3-150µgkg -1 under optimal reagent conditions (1.75mL of 0.1molL -1 ammonia buffer at pH 9.0, 2.2mgL -1 Ni(II), 4.0×10 -4 molL -1 F 2- , 0.4% (w/v) NH 4 Cl and 0.7% (v/v) PONPE 7.5) with sensitivity enhancement of 160-fold. The proposed method has been validated by assessment of the following parameters; the limits of detection (LOD) and quantification (LOQ) (0.08µgkg -1 and 0.28µgkg -1 , respectively) with a relative standard deviation (RSD%) lower than 6.3%, and extractive recovery higher than 95% for acrylamide spiked at levels of 5 and 25µgkg -1 . The method was successfully applied to the indirect determination of acrylamide in the processed foods and two CRMs with satisfactory results. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Combination of dispersive liquid-liquid microextraction with flame atomic absorption spectrometry using microsample introduction for determination of lead in water samples.

    PubMed

    Naseri, Mohammad Taghi; Hemmatkhah, Payam; Hosseini, Mohammad Reza Milani; Assadi, Yaghoub

    2008-03-03

    The dispersive liquid-liquid microextraction (DLLME) was combined with the flame atomic absorption spectrometry (FAAS) for determination of lead in the water samples. Diethyldithiophosphoric acid (DDTP), carbon tetrachloride and methanol were used as chelating agent, extraction solvent and disperser solvent, respectively. A new FAAS sample introduction system was employed for the microvolume nebulization of the non-flammable chlorinated organic extracts. Injection of 20 microL volumes of the organic extract into an air-acetylene flame provided very sensitive spike-like and reproducible signals. Some effective parameters on the microextraction and the complex formation were selected and optimized. These parameters include extraction and disperser solvent type as well as their volume, extraction time, salt effect, pH and amount of the chelating agent. Under the optimized conditions, the enrichment factor of 450 was obtained from a sample volume of 25.0 mL. The enhancement factor, calculated as the ratio of the slopes of the calibration graphs with and without preconcentration, which was about 1000. The calibration graph was linear in the range of 1-70 microgL(-1) with a detection limit of 0.5 microgL(-1). The relative standard deviation (R.S.D.) for seven replicate measurements of 5.0 and 50 microgL(-1) of lead were 3.8 and 2.0%, respectively. The relative recoveries of lead in tap, well, river and seawater samples at the spiking level of 20 microgL(-1) ranged from 93.8 to 106.2%. The characteristics of the proposed method were compared with those of the liquid-liquid extraction (LLE), cloud point extraction (CPE), on-line and off-line solid-phase extraction (SPE) as well as co-precipitation, based on bibliographic data. Operation simplicity, rapidity, low cost, high enrichment factor, good repeatability, and low consumption of the extraction solvent at a microliter level are the main advantages of the proposed method.

  7. Constraining the Intergalactic and Circumgalactic Media with Lyman-Alpha Absorption

    NASA Astrophysics Data System (ADS)

    Sorini, Daniele; Onorbe, Jose; Hennawi, Joseph F.; Lukic, Zarija

    2018-01-01

    Lyman-alpha (Ly-a) absorption features detected in quasar spectra in the redshift range 0part of my thesis, I overcome numerical challenges posed by cosmological hydrodynamic simulations by developing a novel semi-analytic technique to predict various statistics of Ly-a absorption in the IGM with large N-body cosmological simulations. The technique developed is more accurate than previous attempts in the literature, and can be applied to Gpc-scale N-body simulations, allowing an accurate investigation of the Ly-a absorption on unprecedentedly large scales. In the second part of my thesis, I compare predictions of state-of-the-art hydrodynamic cosmological simulations with observations of the mean Ly-a absorption around foreground quasars, damped Ly-a absorbers, and Lyman-break galaxies, at different transverse distances (~20kpc-20Mpc) from background quasars. Far from galaxies >2Mpc, the simulations asymptotically match the observations, because the ΛCDM model successfully describes the ambient IGM. This represents a critical advantage of studying the mean absorption profile. However, significant differences between the simulations, and between simulations and observations are present on scales 20kpc-2Mpc, illustrating the challenges of accurately modeling and resolving galaxy formation physics. It is noteworthy that these differences are observed as far out as ~2Mpc, indicating that the `sphere-of-influence' of galaxies could extend to approximately ~20 times the halo virial radius (~100kpc). Current observations are very precise on these scales and can thus strongly discriminate between different galaxy formation models. I demonstrate that the Ly-a absorption profile is primarily sensitive to the underlying temperature-density relationship of diffuse gas around galaxies, and argue that it

  8. Three-wave mixing in conjugated polymer solutions: Two-photon absorption in polydiacetylenes

    NASA Astrophysics Data System (ADS)

    Chance, R. R.; Shand, M. L.; Hogg, C.; Silbey, R.

    1980-10-01

    Three-wave-mixing spectroscopy is used to determine the dispersive and absorptive parts of a strongly allowed two-photon transition in a series of polydiacetylene solutions. The data analysis yields the energy, width, symmetry assignment, and oscillator strength for the two-photon transition. The data conclusively demonstrate that strong two-photon absorption is a fundamental property of the polydiacetylene backbone. The remarkably large two-photon absorption coefficients are explained by large oscillator strengths for both transitions involved in the two-photon absorption combined with strong one-photon resonance effects. The experimental results are shown to be consistent with a simple theoretical model for the energies and oscillator strengths of the one- and two-photon-allowed transitions.

  9. Effect of nonlinear absorption on self focusing of short laser pulse in a plasma

    NASA Astrophysics Data System (ADS)

    Kumar, Ashok

    2012-06-01

    Paraxial theory of self focusing of short pulse laser in a plasma under transient and saturating effects of nonlinearity and nonlinear absorption is developed. The absorption is averaged over the cross-section of the beam and is different for different time segments of the pulse. The electron temperature includes cumulative effect of previous history of temporal profile of pulse intensity, however, the ambipolar diffusion is taken to be faster than the heating time. The relaxation effect causes self-distortion of the pulse temporal profile where as the nonlinear absorption weakens self focusing. For the pulses of duration comparable to the electron ion collision time, the front part of the pulse gets defocused where as the latter part undergoes periodic self focusing.

  10. Separation and preconcentration of Ag(I) in aqueous samples by flotation as an ion-associate using iodide and ferroin followed the determination by flame atomic absorption spectrometry.

    PubMed

    Hosseini, Mohammad Saeid; Hashemi-Moghaddam, Hamid; Kardan-Moghaddam, Gholamreza

    2007-01-01

    A simple method for separation/preconcentration and determination of Ag(I) in aqueous samples is described. The method is based on formation of an ion-associate between Ag(I)-iodide complex and ferroin, which can be floated at the interface of the aqueous/n-heptane phases. The flotation process was carried out using 500-ml aliquot of the aqueous solution and the floated layer was dissolved in 5 ml of 1 M HNO3 containing methanol (50% v/v) as the solvent. The Ag(I) content was then determined by flame atomic absorption spectrometry (FAAS). The method so could be considered as an enrichment process, was achieved to a quantitative feature, when the pH of the solution was adjusted to 4 and the concentrations of iodide and ferroin were about 3.2 x 10(-4) M and 6.25 x 10(-5) M, respectively. The LOD and RSD (n = 7) were obtained 1.0 x 10(-8) M and 2.4%, respectively. It was found that a large number of cations and anions even at high considerably foreign ion/Ag(I) ratios were not interfered. The method was applied satisfactorily to recovery of Ag(I) from different aqueous samples.

  11. Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of arsenic and selenium in water and sediment by graphite furnace atomic absorption spectrometry

    USGS Publications Warehouse

    Jones, Sandra R.; Garbarino, John R.

    1999-01-01

    Graphite furnace-atomic absorption spectrometry (GF-AAS) is a sensitive, precise, and accurate technique that can be used to determine arsenic and selenium in samples of water and sediment. The GF-AAS method has been developed to replace the hydride generation-atomic absorption spectrometry (HG-AAS) methods because the method detection limits are similar, bias and variability are comparable, and interferences are minimal. Advantages of the GF-AAS method include shorter sample preparation time, increased sample throughput from simultaneous multielement analysis, reduced amount of chemical waste, reduced sample volume requirements, increased linear concentration range, and the use of a more accurate digestion procedure. The linear concentration range for arsenic and selenium is 1 to 50 micrograms per liter in solution; the current method detection limit for arsenic in solution is 0.9 microgram per liter; the method detection limit for selenium in solution is 1 microgram per liter. This report describes results that were obtained using stop-flow and low-flow conditions during atomization. The bias and variability of the simultaneous determination of arsenic and selenium by GF-AAS under both conditions are supported with results from standard reference materials--water and sediment, real water samples, and spike recovery measurements. Arsenic and selenium results for all Standard Reference Water Samples analyzed were within one standard deviation of the most probable values. Long-term spike recoveries at 6.25, 25.0, 37.5 micrograms per liter in reagent-, ground-, and surface-water samples for arsenic averaged 103 plus or minus 2 percent using low-flow conditions and 104 plus or minus 4 percent using stop-flow conditions. Corresponding recoveries for selenium were 98 plus or minus 13 percent using low-flow conditions and 87 plus or minus 24 percent using stop-flow conditions. Spike recoveries at 25 micrograms per liter in 120 water samples ranged from 97 to 99 percent

  12. The allure of mass spectrometry: From an earlyday chemist's perspective.

    PubMed

    Tőkés, László

    2017-07-01

    sensitivity TCDD analyses and other projects. Reflecting on my services for the mass spectrometry society, involvements with the co-founding and 12 year chairing of the Asilomar Conference on Mass Spectrometry and founding of the Bay Area Mass Spectrometry regional MS discussion group, as part of my services for the mass spectrometry community, are presented in some detail. © 2016 Wiley Periodicals, Inc. Mass Spec Rev 36:520-542, 2017. © 2016 The Authors. Mass Spectrometry Reviews Published by Wiley Periodicals, Inc.

  13. Sound absorption of microperforated panels inside compact acoustic enclosures

    NASA Astrophysics Data System (ADS)

    Yang, Cheng; Cheng, Li

    2016-01-01

    This paper investigates the sound absorption effect of microperforated panels (MPPs) in small-scale enclosures, an effort stemming from the recent interests in using MPPs for noise control in compact mechanical systems. Two typical MPP backing cavity configurations (an empty backing cavity and a honeycomb backing structure) are studied. Although both configurations provide basically the same sound absorption curves from standard impedance tube measurements, their in situ sound absorption properties, when placed inside a small enclosure, are drastically different. This phenomenon is explained using a simple system model based on modal analyses. It is shown that the accurate prediction of the in situ sound absorption of the MPPs inside compact acoustic enclosures requires meticulous consideration of the configuration of the backing cavity and its coupling with the enclosure in front. The MPP structure should be treated as part of the entire system, rather than an absorption boundary characterized by the surface impedance, calculated or measured in simple acoustic environment. Considering the spatial matching between the acoustic fields across the MPP, the possibility of attenuating particular enclosure resonances by partially covering the enclosure wall with a properly designed MPP structure is also demonstrated.

  14. Evolution of a detailed physiological model to simulate the gastrointestinal transit and absorption process in humans, part II: extension to describe performance of solid dosage forms.

    PubMed

    Thelen, Kirstin; Coboeken, Katrin; Willmann, Stefan; Dressman, Jennifer B; Lippert, Jörg

    2012-03-01

    The physiological absorption model presented in part I of this work is now extended to account for dosage-form-dependent gastrointestinal (GI) transit as well as disintegration and dissolution processes of various immediate-release and modified-release dosage forms. Empirical functions of the Weibull type were fitted to experimental in vitro dissolution profiles of solid dosage forms for eight test compounds (aciclovir, caffeine, cimetidine, diclofenac, furosemide, paracetamol, phenobarbital, and theophylline). The Weibull functions were then implemented into the model to predict mean plasma concentration-time profiles of the various dosage forms. On the basis of these dissolution functions, pharmacokinetics (PK) of six model drugs was predicted well. In the case of diclofenac, deviations between predicted and observed plasma concentrations were attributable to the large variability in gastric emptying time of the enteric-coated tablets. Likewise, oral PK of furosemide was found to be predominantly governed by the gastric emptying patterns. It is concluded that the revised model for GI transit and absorption was successfully integrated with dissolution functions of the Weibull type, enabling prediction of in vivo PK profiles from in vitro dissolution data. It facilitates a comparative analysis of the parameters contributing to oral drug absorption and is thus a powerful tool for formulation design. Copyright © 2011 Wiley Periodicals, Inc.

  15. Slurry sampling high-resolution continuum source electrothermal atomic absorption spectrometry for direct beryllium determination in soil and sediment samples after elimination of SiO interference by least-squares background correction.

    PubMed

    Husáková, Lenka; Urbanová, Iva; Šafránková, Michaela; Šídová, Tereza

    2017-12-01

    In this work a simple, efficient, and environmentally-friendly method is proposed for determination of Be in soil and sediment samples employing slurry sampling and high-resolution continuum source electrothermal atomic absorption spectrometry (HR-CS-ETAAS). The spectral effects originating from SiO species were identified and successfully corrected by means of a mathematical correction algorithm. Fractional factorial design has been employed to assess the parameters affecting the analytical results and especially to help in the development of the slurry preparation and optimization of measuring conditions. The effects of seven analytical variables including particle size, concentration of glycerol and HNO 3 for stabilization and analyte extraction, respectively, the effect of ultrasonic agitation for slurry homogenization, concentration of chemical modifier, pyrolysis and atomization temperature were investigated by a 2 7-3 replicate (n = 3) design. Using the optimized experimental conditions, the proposed method allowed the determination of Be with a detection limit being 0.016mgkg -1 and characteristic mass 1.3pg. Optimum results were obtained after preparing the slurries by weighing 100mg of a sample with particle size < 54µm and adding 25mL of 20% w/w glycerol. The use of 1μg Rh and 50μg citric acid was found satisfactory for the analyte stabilization. Accurate data were obtained with the use of matrix-free calibration. The accuracy of the method was confirmed by analysis of two certified reference materials (NIST SRM 2702 Inorganics in Marine Sediment and IGI BIL-1 Baikal Bottom Silt) and by comparison of the results obtained for ten real samples by slurry sampling with those determined after microwave-assisted extraction by inductively coupled plasma time of flight mass spectrometry (TOF-ICP-MS). The reported method has a precision better than 7%. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Laser Ablation-Aerosol Mass Spectrometry-Chemical Ionization Mass Spectrometry for Ambient Surface Imaging

    DOE PAGES

    Berry, Jennifer L.; Day, Douglas A.; Elseberg, Tim; ...

    2018-02-20

    Mass spectrometry imaging is becoming an increasingly common analytical technique due to its ability to provide spatially resolved chemical information. In this paper, we report a novel imaging approach combining laser ablation with two mass spectrometric techniques, aerosol mass spectrometry and chemical ionization mass spectrometry, separately and in parallel. Both mass spectrometric methods provide the fast response, rapid data acquisition, low detection limits, and high-resolution peak separation desirable for imaging complex samples. Additionally, the two techniques provide complementary information with aerosol mass spectrometry providing near universal detection of all aerosol molecules and chemical ionization mass spectrometry with a heated inletmore » providing molecular-level detail of both gases and aerosols. The two techniques operate with atmospheric pressure interfaces and require no matrix addition for ionization, allowing for samples to be investigated in their native state under ambient pressure conditions. We demonstrate the ability of laser ablation-aerosol mass spectrometry-chemical ionization mass spectrometry (LA-AMS-CIMS) to create 2D images of both standard compounds and complex mixtures. Finally, the results suggest that LA-AMS-CIMS, particularly when combined with advanced data analysis methods, could have broad applications in mass spectrometry imaging applications.« less

  17. Laser Ablation-Aerosol Mass Spectrometry-Chemical Ionization Mass Spectrometry for Ambient Surface Imaging

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Berry, Jennifer L.; Day, Douglas A.; Elseberg, Tim

    Mass spectrometry imaging is becoming an increasingly common analytical technique due to its ability to provide spatially resolved chemical information. In this paper, we report a novel imaging approach combining laser ablation with two mass spectrometric techniques, aerosol mass spectrometry and chemical ionization mass spectrometry, separately and in parallel. Both mass spectrometric methods provide the fast response, rapid data acquisition, low detection limits, and high-resolution peak separation desirable for imaging complex samples. Additionally, the two techniques provide complementary information with aerosol mass spectrometry providing near universal detection of all aerosol molecules and chemical ionization mass spectrometry with a heated inletmore » providing molecular-level detail of both gases and aerosols. The two techniques operate with atmospheric pressure interfaces and require no matrix addition for ionization, allowing for samples to be investigated in their native state under ambient pressure conditions. We demonstrate the ability of laser ablation-aerosol mass spectrometry-chemical ionization mass spectrometry (LA-AMS-CIMS) to create 2D images of both standard compounds and complex mixtures. Finally, the results suggest that LA-AMS-CIMS, particularly when combined with advanced data analysis methods, could have broad applications in mass spectrometry imaging applications.« less

  18. Synthesis and application of a nanoporous ion-imprinted polymer for the separation and preconcentration of trace amounts of vanadium from food samples before determination by electrothermal atomic absorption spectrometry.

    PubMed

    Dadfarnia, Shayessteh; Haji Shabani, Ali Mohammad; Dehghanpoor Frashah, Shahab

    2016-04-01

    A vanadium ion-imprinted polymer was synthesized in the presence of V(V) and N-benzoyl-N-phenyl hydroxyl amine using 4-vinyl pyridine as the monomer, ethylene glycol dimethacrylate as the cross linker and 2,2'-azobis(isobutyronitrile) as the initiator. The imprinted V(V) ions were completely removed by leaching the polymer with 5 mol/L nitric acid, and the polymer structure was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The ion-imprinted polymer was used as the sorbent in the development of the solid-phase extraction method for V(V) prior to its determination by electrothermal atomic absorption spectrometry. The maximum sorption capacity for V(V) ions was 26.7 mg/g at pH 4.0. Under the optimum conditions, for a sample volume of 150.0 mL, an enrichment factor of 289.0 and a detection limit of 6.4 ng/L were obtained. The developed method was successfully applied to the determination of vanadium in parsley, zucchini, black tea, rice, and water samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Absorption Voltages and Insulation Resistance in Ceramic Capacitors with Cracks

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2016-01-01

    Time dependence of absorption voltages (Vabs) in different types of low-voltage X5R and X7R ceramic capacitors was monitored for a maximum duration of hundred hours after polarization. To evaluate the effect of mechanical defects on Vabs, cracks in the dielectric were introduced either mechanically or by thermal shock. The maximum absorption voltage, time to roll-off, and the rate of voltage decrease are shown to depend on the crack-related leakage currents and insulation resistance in the parts. A simple model that is based on the Dow equivalent circuit for capacitors with absorption has been developed to assess the insulation resistance of capacitors. Standard measurements of the insulation resistance, contrary to the measurements based on Vabs, are not sensitive to the presence of mechanical defects and fail to reveal capacitors with cracks. Index Terms: Ceramic capacitor, insulation resistance, dielectric absorption, cracking.

  20. Ionic liquid-assisted multiwalled carbon nanotube-dispersive micro-solid phase extraction for sensitive determination of inorganic As species in garlic samples by electrothermal atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Grijalba, Alexander Castro; Escudero, Leticia B.; Wuilloud, Rodolfo G.

    2015-08-01

    A highly sensitive dispersive micro-solid phase extraction (D-μ-SPE) method combining an ionic liquid (IL) and multi-walled carbon nanotubes (MWCNTs) for inorganic As species (As(III) and As(V)) species separation and determination in garlic samples by electrothermal atomic absorption spectrometry (ETAAS) was developed. Trihexyl(tetradecil)phosphonium chloride IL was used to form an ion pair with the arsenomolybdate complex obtained by reaction of As(V) with molybdate ion. Afterwards, 1.0 mg of MWCNTs was dispersed for As(V) extraction and the supernatant was separated by centrifugation. MWCNTs were re-dispersed with tetradecyltrimethylammonium bromide surfactant and ultrasound followed by direct injection into the graphite furnace of ETAAS for As determination. Pyrolysis and atomization conditions were carefully studied for complete decomposition of MWCNTs and IL matrices. Under optimum conditions, an extraction efficiency of 100% and a preconcentration factor of 70 were obtained with 5 mL of garlic extract. The detection limit was 7.1 ng L- 1 and the relative standard deviations (RSDs) for six replicate measurements at 5 μg L- 1 of As were 5.4% and 4.8% for As(III) and As(V), respectively. The proposed D-μ-SPE method allowed the efficient separation and determination of inorganic As species in a complex matrix such as garlic extract.

  1. Seven-effect absorption refrigeration

    DOEpatents

    DeVault, Robert C.; Biermann, Wendell J.

    1989-01-01

    A seven-effect absorption refrigeration cycle is disclosed utilizing three absorption circuits. In addition, a heat exchanger is used for heating the generator of the low absorption circuit with heat rejected from the condenser and absorber of the medium absorption circuit. A heat exchanger is also provided for heating the generator of the medium absorption circuit with heat rejected from the condenser and absorber of the high absorption circuit. If desired, another heat exchanger can also be provided for heating the evaporator of the high absorption circuit with rejected heat from either the condenser or absorber of the low absorption circuit.

  2. Seven-effect absorption refrigeration

    DOEpatents

    DeVault, R.C.; Biermann, W.J.

    1989-05-09

    A seven-effect absorption refrigeration cycle is disclosed utilizing three absorption circuits. In addition, a heat exchanger is used for heating the generator of the low absorption circuit with heat rejected from the condenser and absorber of the medium absorption circuit. A heat exchanger is also provided for heating the generator of the medium absorption circuit with heat rejected from the condenser and absorber of the high absorption circuit. If desired, another heat exchanger can also be provided for heating the evaporator of the high absorption circuit with rejected heat from either the condenser or absorber of the low absorption circuit. 1 fig.

  3. Translational value of liquid chromatography coupled with tandem mass spectrometry-based quantitative proteomics for in vitro-in vivo extrapolation of drug metabolism and transport and considerations in selecting appropriate techniques.

    PubMed

    Al Feteisi, Hajar; Achour, Brahim; Rostami-Hodjegan, Amin; Barber, Jill

    2015-01-01

    Drug-metabolizing enzymes and transporters play an important role in drug absorption, distribution, metabolism and excretion and, consequently, they influence drug efficacy and toxicity. Quantification of drug-metabolizing enzymes and transporters in various tissues is therefore essential for comprehensive elucidation of drug absorption, distribution, metabolism and excretion. Recent advances in liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) have improved the quantification of pharmacologically relevant proteins. This report presents an overview of mass spectrometry-based methods currently used for the quantification of drug-metabolizing enzymes and drug transporters, mainly focusing on applications and cost associated with various quantitative strategies based on stable isotope-labeled standards (absolute quantification peptide standards, quantification concatemers, protein standards for absolute quantification) and label-free analysis. In mass spectrometry, there is no simple relationship between signal intensity and analyte concentration. Proteomic strategies are therefore complex and several factors need to be considered when selecting the most appropriate method for an intended application, including the number of proteins and samples. Quantitative strategies require appropriate mass spectrometry platforms, yet choice is often limited by the availability of appropriate instrumentation. Quantitative proteomics research requires specialist practical skills and there is a pressing need to dedicate more effort and investment to training personnel in this area. Large-scale multicenter collaborations are also needed to standardize quantitative strategies in order to improve physiologically based pharmacokinetic models.

  4. Influence of ascorbic acid on iron absorption from an iron-fortified, chocolate-flavored milk drink in Jamaican children.

    PubMed

    Davidsson, L; Walczyk, T; Morris, A; Hurrell, R F

    1998-05-01

    The influence of ascorbic acid on iron absorption from an iron-fortified, chocolate-flavored milk drink (6.3 mg total Fe per serving) was evaluated with a stable-isotope technique in 20 6-7-y-old Jamaican children. Each child received two test meals labeled with 5.6 mg 57Fe and 3.0 mg 58Fe as ferrous sulfate on 2 consecutive days. Three different doses of ascorbic acid (0, 25, and 50 mg per 25-g serving) were evaluated in two separate studies by using a crossover design. Iron isotope ratios were measured by negative thermal ionization mass spectrometry. In the first study, iron absorption was significantly greater (P < 0.0001) after the addition of 25 mg ascorbic acid: geometric mean iron absorption was 1.6% (range: 0.9-4.2%) and 5.1% (2.2-17.3%) for the test meals containing 0 and 25 mg ascorbic acid, respectively. In the second study, a significant difference (P < 0.05) in iron absorption was observed when the ascorbic acid content was increased from 25 to 50 mg: geometric mean iron absorption was 5.4% (range: 2.7-10.8%) compared with 7.7% (range: 4.7-16.5%), respectively. The chocolate drink contained relatively high amounts of polyphenolic compounds, phytic acid, and calcium, all well-known inhibitors of iron absorption. The low iron absorption without added ascorbic acid shows that chocolate milk is a poor vehicle for iron fortification unless sufficient amounts of an iron-absorption enhancer are added. Regular consumption of iron-fortified chocolate milk drinks containing added ascorbic acid could have a positive effect on iron nutrition in population groups vulnerable to iron deficiency.

  5. Imaging Mass Spectrometry on the Nanoscale with Cluster Ion Beams

    PubMed Central

    2015-01-01

    Imaging with cluster secondary ion mass spectrometry (SIMS) is reaching a mature level of development. Using a variety of molecular ion projectiles to stimulate desorption, 3-dimensional imaging with the selectivity of mass spectrometry can now be achieved with submicrometer spatial resolution and <10 nm depth resolution. In this Perspective, stock is taken regarding what it will require to routinely achieve these remarkable properties. Issues include the chemical nature of the projectile, topography formation, differential erosion rates, and perhaps most importantly, ionization efficiency. Shortcomings of existing instrumentation are also noted. Speculation about how to successfully resolve these issues is a key part of the discussion. PMID:25458665

  6. The allure of mass spectrometry: From an earlyday chemist's perspective

    PubMed Central

    2016-01-01

    containers, high sensitivity TCDD analyses and other projects. Reflecting on my services for the mass spectrometry society, involvements with the co‐founding and 12 year chairing of the Asilomar Conference on Mass Spectrometry and founding of the Bay Area Mass Spectrometry regional MS discussion group, as part of my services for the mass spectrometry community, are presented in some detail. © 2016 Wiley Periodicals, Inc. Mass Spec Rev 36:520–542, 2017 PMID:26999732

  7. Varied absorption peaks of dual-band metamaterial absorber analysis by using reflection theory

    NASA Astrophysics Data System (ADS)

    Xiong, Han; Yu, Yan-Tao; Tang, Ming-Chun; Chen, Shi-Yong; Liu, Dan-Ping; Ou, Xiang; Zeng, Hao

    2016-03-01

    Cross-resonator metamaterial absorbers (MMA) have been widely investigated from microwave to optical frequencies. However, only part of the factors influencing the absorption properties were analyzed in previous works at the same time. In order to completely understand how the spacer thickness, dielectric parameter and incidence angle affect the absorption properties of the dual-band MMA, two sets of simulation were performed. It was found that with increasing incident angles, the low-frequency absorption peak showed a blue shift, while the high-frequency absorption peaks showed a red shift. However, with the increase in spacer thickness, both of the absorption peaks showed a red shift. By using the reflection theory expressions, the physical mechanism of the cross-resonator MMA was well explained. This method provides an effective way to analyze multi-band absorber in technology.

  8. Ligandless surfactant mediated solid phase extraction combined with Fe₃O₄ nano-particle for the preconcentration and determination of cadmium and lead in water and soil samples followed by flame atomic absorption spectrometry: multivariate strategy.

    PubMed

    Jalbani, N; Soylak, M

    2014-04-01

    In the present study, a microextraction technique combining Fe3O4 nano-particle with surfactant mediated solid phase extraction ((SM-SPE)) was successfully developed for the preconcentration/separation of Cd(II) and Pb(II) in water and soil samples. The analytes were determined by flame atomic absorption spectrometry (FAAS). The effective variables such as the amount of adsorbent (NPs), the pH, concentration of non-ionic (TX-114) and centrifugation time (min) were investigated by Plackett-Burman (PBD) design. The important variables were further optimized by central composite design (CCD). Under the optimized conditions, the detection limits (LODs) of Cd(II) and Pb(II) were 0.15 and 0.74 µg/L, respectively. The validation of the proposed procedure was checked by the analysis of certified reference materials of TMDA 53.3 fortified water and GBW07425 soil. The method was successfully applied for the determination of Cd(II) and Pb(II) in water and soil samples. Copyright © 2014 Elsevier Inc. All rights reserved.

  9. Direct determination of chromium in infant formulas employing high-resolution continuum source electrothermal atomic absorption spectrometry and solid sample analysis.

    PubMed

    Silva, Arlene S; Brandao, Geovani C; Matos, Geraldo D; Ferreira, Sergio L C

    2015-11-01

    The present work proposed an analytical method for the direct determination of chromium in infant formulas employing the high-resolution continuum source electrothermal atomic absorption spectrometry combined with the solid sample analysis (SS-HR-CS ET AAS). Sample masses up to 2.0mg were directly weighted on a solid sampling platform and introduced into the graphite tube. In order to minimize the formation of carbonaceous residues and to improve the contact of the modifier solution with the solid sample, a volume of 10 µL of a solution containing 6% (v/v) H2O2, 20% (v/v) ethanol and 1% (v/v) HNO3 was added. The pyrolysis and atomization temperatures established were 1600 and 2400 °C, respectively, using magnesium as chemical modifier. The calibration technique was evaluated by comparing the slopes of calibration curves established using aqueous and solid standards. This test revealed that chromium can be determined employing the external calibration technique using aqueous standards. Under these conditions, the method developed allows the direct determination of chromium with limit of quantification of 11.5 ng g(-1), precision expressed as relative standard deviation (RSD) in the range of 4.0-17.9% (n=3) and a characteristic mass of 1.2 pg of chromium. The accuracy was confirmed by analysis of a certified reference material of tomato leaves furnished by National Institute of Standards and Technology. The method proposed was applied for the determination of chromium in five different infant formula samples. The chromium content found varied in the range of 33.9-58.1 ng g(-1) (n=3). These samples were also analyzed employing ICP-MS. A statistical test demonstrated that there is no significant difference between the results found by two methods. The chromium concentrations achieved are lower than the maximum limit permissible for chromium in foods by Brazilian Legislation. Copyright © 2015. Published by Elsevier B.V.

  10. Primary gas thermometry by means of laser-absorption spectroscopy: determination of the Boltzmann constant.

    PubMed

    Casa, G; Castrillo, A; Galzerano, G; Wehr, R; Merlone, A; Di Serafino, D; Laporta, P; Gianfrani, L

    2008-05-23

    We report on a new optical implementation of primary gas thermometry based on laser-absorption spectrometry in the near infrared. The method consists in retrieving the Doppler broadening from highly accurate observations of the line shape of the R(12) nu1+2nu2(0)+nu3 transition in CO2 gas at thermodynamic equilibrium. Doppler width measurements as a function of gas temperature, ranging between the triple point of water and the gallium melting point, allowed for a spectroscopic determination of the Boltzmann constant with a relative accuracy of approximately 1.6 x 10(-4).

  11. Primary Gas Thermometry by Means of Laser-Absorption Spectroscopy: Determination of the Boltzmann Constant

    NASA Astrophysics Data System (ADS)

    Casa, G.; Castrillo, A.; Galzerano, G.; Wehr, R.; Merlone, A.; di Serafino, D.; Laporta, P.; Gianfrani, L.

    2008-05-01

    We report on a new optical implementation of primary gas thermometry based on laser-absorption spectrometry in the near infrared. The method consists in retrieving the Doppler broadening from highly accurate observations of the line shape of the R(12) ν1+2ν20+ν3 transition in CO2 gas at thermodynamic equilibrium. Doppler width measurements as a function of gas temperature, ranging between the triple point of water and the gallium melting point, allowed for a spectroscopic determination of the Boltzmann constant with a relative accuracy of ˜1.6×10-4.

  12. Sulfur determination in coal using molecular absorption in graphite filter vaporizer.

    PubMed

    Jim, Gibson; Katskov, Dmitri; Tittarelli, Paolo

    2011-02-15

    The vaporization of sulfur containing samples in graphite vaporizers for atomic absorption spectrometry is accompanied by modification of sulfur by carbon and, respectively, appearance at high temperature of structured molecular absorption in 200-210 nm wavelength range. It has been proposed to employ the spectrum for direct determination of sulfur in coal; soundness of the suggestion is evaluated by analysis of coal slurry using low resolution CCD spectrometer with continuum light source coupled to platform or filter furnace vaporizers. For coal in platform furnace losses of the analyte at low temperature and strong spectral background from the coal matrix hinder the determination. Both negative effects are significantly reduced in filter furnace, in which sample vapor efficiently interacts with carbon when transferred through the heated graphite filter. The method is verified by analysis of coals with sulfur content within 0.13-1.5% (m/m) range. The use of coal certified reference material for sulfur analyte addition to coal slurry permitted determination with random error 5-12%. Absolute and relative detection limits for sulfur in coal are 0.16 μg and 0.02 mass%, respectively. Copyright © 2010 Elsevier B.V. All rights reserved.

  13. Ultratrace determination of arsenic in water samples by electrothermal atomic absorption spectrometry after pre-concentration with Mg-Al-Fe ternary layered double hydroxide nano-sorbent.

    PubMed

    Abdolmohammad-Zadeh, Hossein; Jouyban, Abolghasem; Amini, Roghayeh

    2013-11-15

    A selective solid phase extraction method, based on nano-structured Mg-Al-Fe(NO3(-)) ternary layered double hydroxide as a sorbent, is developed for the pre-concentration of ultra-trace levels of arsenic (As) prior to determination by electrothermal atomic absorption spectrometry. It is found that both As(III) and As(V) could be quantitatively retained on the sorbent within a wide pH range of 4-12. Accordingly, the presented method is applied to determination of total inorganic As in aqueous solutions. Maximum analytical signal of As is achieved when the pyrolysis and atomization temperatures are close to 900 °C and 2300 °C, respectively. Several variables affecting the extraction efficiency including pH, sample flow rate, amount of nano-sorbent, elution conditions and sample volume are optimized. Under the optimized conditions, the limit of detection (3Sb/m) and the relative standard deviation are 4.6 pg mL(-1) and 3.9%, respectively. The calibration graph is linear in the range of 15.0-650 pg mL(-1) with a correlation coefficient of 0.9979, sorption capacity and pre-concentration factor are 8.68 mg g(-1) and 300, respectively. The developed method is validated by the analysis of a standard reference material (SRM 1643e) and is successfully applied to the determination of ultra-trace amounts of As in different water samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Mapping of lead, magnesium and copper accumulation in plant tissues by laser-induced breakdown spectroscopy and laser-ablation inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Kaiser, J.; Galiová, M.; Novotný, K.; Červenka, R.; Reale, L.; Novotný, J.; Liška, M.; Samek, O.; Kanický, V.; Hrdlička, A.; Stejskal, K.; Adam, V.; Kizek, R.

    2009-01-01

    Laser-Induced Breakdown Spectroscopy (LIBS) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) were utilized for mapping the accumulation of Pb, Mg and Cu with a resolution up to 200 μm in a up to cm × cm area of sunflower ( Helianthus annuus L.) leaves. The results obtained by LIBS and LA-ICP-MS are compared with the outcomes from Atomic Absorption Spectrometry (AAS) and Thin-Layer Chromatography (TLC). It is shown that laser-ablation based analytical methods can substitute or supplement these techniques mainly in the cases when a fast multi-elemental mapping of a large sample area is needed.

  15. Development of new portable miniaturize solid phase microextraction of silver-APDC complex using micropipette tip in-syringe system couple with electrothermal atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Naeemullah; Kazi, Tasneem Gul; Afridi, Hassan Imran; Shah, Faheem; Arain, Sadaf Sadia; Arain, Salma Aslam; Panhwar, Abdul Haleem; Arain, Mariam Shahzadi; Samoon, Muhammad Kashif

    2016-02-01

    An innovative and simple miniaturized solid phase microextraction (M-SPME) method, was developed for preconcentration and determination of silver(I) in the fresh and waste water samples. For M-SPME, a micropipette tip packed with activated carbon cloth (ACC) as sorbent, in a syringe system. The size, morphology and elemental composition of ACC before and after adsorption of analyte have been characterized by scanning electron microscopy and energy dispersive spectroscopy. The sample solution treated with a complexing reagent, ammonium pyrrolidine dithiocarbamate (APDC), was drawn into the syringe filled with ACC and dispensed manually for 2 to 10 aspirating/dispensing cycle. Then the Ag- complex sorbed on the ACC in micropipette was quantitatively eluted by drawing and dispensing of different concentrations of acids for 2 to 5 aspirating/dispensing cycles. The extracted Ag ions with modifier were injected directly into the electrothermal atomic absorption spectrometry for analysis. The influence of different variables on the extraction efficiency, including the concentration of ligand, pH, sample volume, eluent type, concentration and volume was investigated. Validity and accuracy of the developed method was checked by the standard addition method. Reliability of the proposed methodology was checked by the relative standard deviation (%RSD), which was found to be < 5%. Under the optimized experimental variables, the limits of detection (LOD) and enhancement factors (EF), were obtained to be 0.86 ng L- 1 and 120, respectively. The proposed method was successfully applied for the determination of trace levels of silver ions in fresh and waste water samples.

  16. Development of new portable miniaturize solid phase microextraction of silver-APDC complex using micropipette tip in-syringe system couple with electrothermal atomic absorption spectrometry.

    PubMed

    Naeemullah; Kazi, Tasneem Gul; Afridi, Hassan Imran; Shah, Faheem; Arain, Sadaf Sadia; Arain, Salma Aslam; Panhwar, Abdul Haleem; Arain, Mariam Shahzadi; Samoon, Muhammad Kashif

    2016-02-05

    An innovative and simple miniaturized solid phase microextraction (M-SPME) method, was developed for preconcentration and determination of silver(I) in the fresh and waste water samples. For M-SPME, a micropipette tip packed with activated carbon cloth (ACC) as sorbent, in a syringe system. The size, morphology and elemental composition of ACC before and after adsorption of analyte have been characterized by scanning electron microscopy and energy dispersive spectroscopy. The sample solution treated with a complexing reagent, ammonium pyrrolidine dithiocarbamate (APDC), was drawn into the syringe filled with ACC and dispensed manually for 2 to 10 aspirating/dispensing cycle. Then the Ag- complex sorbed on the ACC in micropipette was quantitatively eluted by drawing and dispensing of different concentrations of acids for 2 to 5 aspirating/dispensing cycles. The extracted Ag ions with modifier were injected directly into the electrothermal atomic absorption spectrometry for analysis. The influence of different variables on the extraction efficiency, including the concentration of ligand, pH, sample volume, eluent type, concentration and volume was investigated. Validity and accuracy of the developed method was checked by the standard addition method. Reliability of the proposed methodology was checked by the relative standard deviation (%RSD), which was found to be <5%. Under the optimized experimental variables, the limits of detection (LOD) and enhancement factors (EF), were obtained to be 0.86 ng L(-1) and 120, respectively. The proposed method was successfully applied for the determination of trace levels of silver ions in fresh and waste water samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Quasar Absorption Studies

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard (Technical Monitor); Elvis, Martin

    2004-01-01

    The aim of the proposal is to investigate the absorption properties of a sample of inter-mediate redshift quasars. The main goals of the project are: Measure the redshift and the column density of the X-ray absorbers; test the correlation between absorption and redshift suggested by ROSAT and ASCA data; constrain the absorber ionization status and metallicity; constrain the absorber dust content and composition through the comparison between the amount of X-ray absorption and optical dust extinction. Unanticipated low energy cut-offs where discovered in ROSAT spectra of quasars and confirmed by ASCA, BeppoSAX and Chandra. In most cases it was not possible to constrain adequately the redshift of the absorber from the X-ray data alone. Two possibilities remain open: a) absorption at the quasar redshift; and b) intervening absorption. The evidences in favour of intrinsic absorption are all indirect. Sensitive XMM observations can discriminate between these different scenarios. If the absorption is at the quasar redshift we can study whether the quasar environment evolves with the Cosmic time.

  18. Electrochemical Dissolution of Iridium and Iridium Oxide Particles in Acidic Media: Transmission Electron Microscopy, Electrochemical Flow Cell Coupled to Inductively Coupled Plasma Mass Spectrometry, and X-ray Absorption Spectroscopy Study.

    PubMed

    Jovanovič, Primož; Hodnik, Nejc; Ruiz-Zepeda, Francisco; Arčon, Iztok; Jozinović, Barbara; Zorko, Milena; Bele, Marjan; Šala, Martin; Šelih, Vid Simon; Hočevar, Samo; Gaberšček, Miran

    2017-09-13

    Iridium-based particles, regarded as the most promising proton exchange membrane electrolyzer electrocatalysts, were investigated by transmission electron microscopy and by coupling of an electrochemical flow cell (EFC) with online inductively coupled plasma mass spectrometry. Additionally, studies using a thin-film rotating disc electrode, identical location transmission and scanning electron microscopy, as well as X-ray absorption spectroscopy have been performed. Extremely sensitive online time-and potential-resolved electrochemical dissolution profiles revealed that Ir particles dissolve well below oxygen evolution reaction (OER) potentials, presumably induced by Ir surface oxidation and reduction processes, also referred to as transient dissolution. Overall, thermally prepared rutile-type IrO 2 particles are substantially more stable and less active in comparison to as-prepared metallic and electrochemically pretreated (E-Ir) analogues. Interestingly, under OER-relevant conditions, E-Ir particles exhibit superior stability and activity owing to the altered corrosion mechanism, where the formation of unstable Ir(>IV) species is hindered. Due to the enhanced and lasting OER performance, electrochemically pre-oxidized E-Ir particles may be considered as the electrocatalyst of choice for an improved low-temperature electrochemical hydrogen production device, namely a proton exchange membrane electrolyzer.

  19. RADIOACTIVE IRON ABSORPTION BY GASTRO-INTESTINAL TRACT

    PubMed Central

    Hahn, P. F.; Bale, W. F.; Ross, J. F.; Balfour, W. M.; Whipple, G. H.

    1943-01-01

    Iron absorption is a function of the gastro-intestinal mucosal epithelium. The normal non-anemic dog absorbs little iron but chronic anemia due to blood loss brings about considerable absorption—perhaps 5 to 15 times normal. In general the same differences are observed in man (1). Sudden change from normal to severe anemia within 24 hours does not significantly increase iron absorption. As the days pass new hemoglobin is formed. The body iron stores are depleted and within 7 days iron absorption is active, even when the red cell hematocrit is rising. Anoxemia of 50 per cent normal oxygen concentration for 48 hours does not significantly enhance iron absorption. In this respect it resembles acute anemia. Ordinary doses of iron given 1 to 6 hours before radio-iron will cause some "mucosa block"—that is an intake of radio-iron less than anticipated. Many variables which modify peristalsis come into this reaction. Iron given by vein some days before the dose of radio-iron does not appear to inhibit iron absorption. Plasma radio-iron absorption curves vary greatly. The curves may show sharp peaks in 1 to 2 hours when the iron is given in an empty stomach but after 6 hours when the radio-iron is given with food. Duration time of curves also varies widely, the plasma iron returning to normal in 6 to 12 hours. Gastric, duodenal, or jejunal pouches all show very active absorption of iron. The plasma concentration peak may reach a maximum before the solution of iron is removed from the gastric pouch—another example of "mucosa block." Absorption and distribution of radio-iron in the body of growing pups give very suggestive experimental data. The spleen, heart, upper gastro-intestinal tract, marrow, and pancreas show more radio-iron than was expected. The term "physiological saturation" with iron may be applied to the gastro-intestinal mucosal epithelium and explain one phase of acceptance or refusal of ingested iron. Desaturation is a matter of days not hours, whereas

  20. Quality assessment of trace Cd and Pb contaminants in Thai herbal medicines using ultrasound-assisted digestion prior to flame atomic absorption spectrometry.

    PubMed

    Siriangkhawut, Watsaka; Sittichan, Patcharee; Ponhong, Kraingkrai; Chantiratikul, Piyanete

    2017-10-01

    A simple, efficient, and reliable ultrasound-assisted digestion (UAD) procedure was used for sample preparation prior to quantitative determination of trace Cd and Pb contaminants in herbal medicines using flame atomic absorption spectrometry. The parameters influencing UAD such as the solvent system, sample mass, presonication time, sonication time, and digestion temperature were evaluated. The efficiency of the proposed UAD procedure was evaluated by comparing with conventional acid digestion (CAD) procedure. Under the optimum conditions, linear calibration graphs in a range of 2-250 μg/L for Cd, and 50-1000 μg/L for Pb were obtained with detection limits of 0.56 μg/L and 10.7 μg/L for Cd and Pb, respectively. The limit of quantification for Cd and Pb were 1.87 μg/L and 40.3 μg/L, respectively. The repeatability for analysis of 10 μg/L for Cd and 100 μg/L for Pb was 2.3% and 2.6%, respectively. The accuracy of the proposed method was evaluated by rice flour certified reference materials. The proposed method was successfully applied for analysis of trace Cd and Pb in samples of various types of medicinal plant and traditional medicine consumed in Thailand. Most herbal medicine samples were not contaminated with Cd or Pb. The contaminant levels for both metals were still lower than the maximum permissible levels of elements in medicinal plant materials and finished herbal products sets by the Ministry of Public Health of Thailand. The exception was the high level of Cd contamination found in two samples of processed medicinal plants. Copyright © 2017. Published by Elsevier B.V.

  1. Speciation analysis of arsenic in biological matrices by automated hydride generation-cryotrapping-atomic absorption spectrometry with multiple microflame quartz tube atomizer (multiatomizer)

    PubMed Central

    Hernández-Zavala, Araceli; Matoušek, Tomáš; Drobná, Zuzana; Paul, David S.; Walton, Felecia; Adair, Blakely M.; Jiří, Dědina; Thomas, David J.

    2008-01-01

    Analyses of arsenic (As) species in tissues and body fluids of individuals chronically exposed to inorganic arsenic (iAs) provide essential information about the exposure level and pattern of iAs metabolism. We have previously described an oxidation state-specific analysis of As species in biological matrices by hydride-generation atomic absorption spectrometry (HG-AAS), using cryotrapping (CT) for preconcentration and separation of arsines. To improve performance and detection limits of the method, HG and CT steps are automated and a conventional flame-in-tube atomizer replaced with a recently developed multiple microflame quartz tube atomizer (multiatomizer). In this system, arsines from AsIII-species are generated in a mixture of Tris-HCl (pH 6) and sodium borohydride. For generation of arsines from both AsIII- and AsV-species, samples are pretreated with L-cysteine. Under these conditions, dimethylthioarsinic acid, a newly described metabolite of iAs, does not interfere significantly with detection and quantification of methylated trivalent arsenicals. Analytical performance of the automated HG-CT-AAS was characterized by analyses of cultured cells and mouse tissues that contained mono- and dimethylated metabolites of iAs. The capacity to detect methylated AsIII- and AsV-species was verified, using an in vitro methylation system containing recombinant rat arsenic (+3 oxidation state) methyltransferase and cultured rat hepatocytes treated with iAs. Compared with the previous HG-CT-AAS design, detection limits for iAs and its metabolites have improved significantly with the current system, ranging from 8 to 20 pg. Recoveries of As were between 78 and 117%. The precision of the method was better than 5% for all biological matrices examined. Thus, the automated HG-CT-AAS system provides an effective and sensitive tool for analysis of all major human metabolites of iAs in complex biological matrices. PMID:18677417

  2. Method validation for control determination of mercury in fresh fish and shrimp samples by solid sampling thermal decomposition/amalgamation atomic absorption spectrometry.

    PubMed

    Torres, Daiane Placido; Martins-Teixeira, Maristela Braga; Cadore, Solange; Queiroz, Helena Müller

    2015-01-01

    A method for the determination of total mercury in fresh fish and shrimp samples by solid sampling thermal decomposition/amalgamation atomic absorption spectrometry (TDA AAS) has been validated following international foodstuff protocols in order to fulfill the Brazilian National Residue Control Plan. The experimental parameters have been previously studied and optimized according to specific legislation on validation and inorganic contaminants in foodstuff. Linearity, sensitivity, specificity, detection and quantification limits, precision (repeatability and within-laboratory reproducibility), robustness as well as accuracy of the method have been evaluated. Linearity of response was satisfactory for the two range concentrations available on the TDA AAS equipment, between approximately 25.0 and 200.0 μg kg(-1) (square regression) and 250.0 and 2000.0 μg kg(-1) (linear regression) of mercury. The residues for both ranges were homoscedastic and independent, with normal distribution. Correlation coefficients obtained for these ranges were higher than 0.995. Limits of quantification (LOQ) and of detection of the method (LDM), based on signal standard deviation (SD) for a low-in-mercury sample, were 3.0 and 1.0 μg kg(-1), respectively. Repeatability of the method was better than 4%. Within-laboratory reproducibility achieved a relative SD better than 6%. Robustness of the current method was evaluated and pointed sample mass as a significant factor. Accuracy (assessed as the analyte recovery) was calculated on basis of the repeatability, and ranged from 89% to 99%. The obtained results showed the suitability of the present method for direct mercury measurement in fresh fish and shrimp samples and the importance of monitoring the analysis conditions for food control purposes. Additionally, the competence of this method was recognized by accreditation under the standard ISO/IEC 17025.

  3. Magnetic solid-phase extraction combined with graphite furnace atomic absorption spectrometry for speciation of Cr(III) and Cr(VI) in environmental waters.

    PubMed

    Jiang, Hong-mei; Yang, Ting; Wang, Yan-hong; Lian, Hong-zhen; Hu, Xin

    2013-11-15

    A new approach of magnetic solid phase extraction (MSPE) coupled with graphite furnace atomic absorption spectrometry (GFAAS) has been developed for the speciation of Cr(III) and Cr(VI) using zincon-immobilized silica-coated magnetic Fe3O4 nanoparticles (Zincon-Si-MNPs) as the MSPE absorbent. Cr(III) was quantitatively reserved on the absorbent at pH 9.1 while total Cr was reserved at pH 6.5. The absorbed Cr species were eluted by using 2 mol/L HCl and detected by GFAAS. The concentration of Cr(VI) could be calculated by subtracting Cr(III) from total Cr. All the parameters affecting the separation and extraction efficiency of Cr species such as pH, extraction time, concentration and volume of eluent, sample volume and influence of co-existing ions were systematically examined and the optimized conditions were established accordingly. The detection limit (LOD) of the method was 0.016 and 0.011 ng mL(-1) for Cr(III) and Cr(VI), respectively, with the enrichment factor of 100 and 150. The precisions of this method (Relative standard deviation, RSD, n=7) for Cr(III) and Cr(VI) at 0.1 ng mL(-1) were 6.0% and 6.2%, respectively. In order to validate the proposed method, a certified reference material of environmental water was analyzed, and the result of Cr speciation was in good agreement with the certified value. This MSPE-GFAAS method has been successfully applied for the speciation of Cr(III) and Cr(VI) in lake and tap waters with the recoveries of 88-109% for the spiked samples. Moreover, the MSPE separation mechanism of Cr(III) and Cr(VI) based on their adsorption-desorption on Zincon-Si-MNPs has been explained through various spectroscopic characterization. © 2013 Elsevier B.V. All rights reserved.

  4. Determination of lead and nickel in environmental samples by flame atomic absorption spectrometry after column solid-phase extraction on Ambersorb-572 with EDTA.

    PubMed

    Baytak, Sitki; Türker, A Rehber

    2006-02-28

    Lead and nickel were preconcentrated as their ethylenediaminetetraacedic acid (EDTA) complexes from aqueous sample solutions using a column containing Ambersorb-572 and determined by flame atomic absorption spectrometry (FAAS). pH values, amount of solid phase, elution solution and flow rate of sample solution have been optimized in order to obtain quantitative recovery of the analytes. The effect of interfering ions on the recovery of the analytes has also been investigated. The recoveries of Pb and Ni under the optimum conditions were 99 +/- 2 and 97 +/- 3%, respectively, at 95% confidence level. Seventy-five-fold (using 750 mL of sample solution and 10 mL of eluent) and 50-fold (using 500 mL of sample solution and 10 mL of eluent) preconcentration was obtained for Pb and Ni, respectively. Time of analysis is about 4.5 h (for obtaining enrichment factor of 75). By applying these enrichment factors, the analytical detection limits of Pb and Ni were found as 3.65 and 1.42 ng mL(-1), respectively. The capacity of the sorbent was found as 0.17 and 0.21 mmol g(-1) for Pb and Ni, respectively. The interferences of some cations, such as Mn2+, Co2+, Fe3+, Al3+, Zn2+, Cd2+, Ca2+, Mg2+, K+ and Na+ usually present in water samples were also studied. This procedure was applied to the determination of lead and nickel in parsley, green onion, sea water and waste water samples. The accuracy of the procedure was checked by determining Pb and Ni in standard reference tea leaves sample (GBW-07605). The results demonstrated good agreement with the certified values.

  5. Conversion electron spectrometry of Pu isotopes with a silicon drift detector.

    PubMed

    Pommé, S; Paepen, J; Peräjärvi, K; Turunen, J; Pöllänen, R

    2016-03-01

    An electron spectrometry set-up was built at IRMM consisting of a vacuum chamber with a moveable source holder and windowless Peltier-cooled silicon drift detector (SDD). The SDD is well suited for measuring low-energy x rays and electrons emitted from thin radioactive sources with low self-absorption. The attainable energy resolution is better than 0.5keV for electrons of 30keV. It has been used to measure the conversion electron spectra of three plutonium isotopes, i.e. (238)Pu, (239)Pu, (240)Pu, as well as (241)Am (being a decay product of (241)Pu). The obtained mixed x-ray and electron spectra are compared with spectra obtained with a close-geometry set-up using another SDD in STUK and spectra measured with a Si(Li) detector at IRMM. The potential of conversion electron spectrometry for isotopic analysis of mixed plutonium samples is investigated. With respect to the (240)Pu/(239)Pu isotopic ratio, the conversion electron peaks of both isotopes are more clearly separated than their largely overlapping peaks in alpha spectra. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  6. Determination of ultratrace elements in natural waters by solid-phase extraction and atomic spectrometry methods.

    PubMed

    Grotti, Marco; Abelmoschi, Maria Luisa; Soggia, Francesco; Frache, Roberto

    2003-01-01

    A study was carried out on the preconcentration of ultratrace amounts of cadmium, lead, manganese, copper and iron from high-salinity aqueous samples and determination by atomic spectrometry methods. Sample volume, amount of resin, loading flow rate, and elution volume were optimized in order to obtain the simultaneous preconcentration of all the analytes. Quantitative recoveries were obtained by using 200 mg of iminodiacetic resin with a loading flow rate of 2 mL min(-1), elution volume of 3 mL and sample volume of 50-450 mL. Only copper in seawater samples was not completely retained by the resin (60-70% recovery), due to unfavorable competition of iminodiacetic-active groups with organically bound metal.To quantify the metals in the eluates, two atomic spectrometry techniques were compared: electrothermal atomization atomic absorption spectrometry (ETAAS) and inductively coupled plasma-optical emission spectrometry (ICP-OES) with simultaneous CCD detection system. Both techniques are suitable for sample analysis with detection limits of 1.0, 4.7, 3.3, 6.8, and 53 ng L(-1) using ETAAS and 12, 122, 3.4, 17, and 21 ng L(-1) using ICP-OES for Cd, Pb, Mn, Cu, and Fe, respectively. Relative standard deviations of the procedures ranged from 1.7 to 14% at the sub-microg L(-1) concentration level. The accuracy of both methods was verified by analyzing various certified reference materials (river water, estuarine water, coastal and off-shore seawater).

  7. Dynamics of Water Absorption and Evaporation During Methanol Droplet Combustion in Microgravity

    NASA Technical Reports Server (NTRS)

    Hicks, Michael C.; Dietrich, Daniel L.; Nayagam, Vedha; Williams, Forman A.

    2012-01-01

    The combustion of methanol droplets is profoundly influenced by the absorption and evaporation of water, generated in the gas phase as a part of the combustion products. Initially there is a water-absorption period of combustion during which the latent heat of condensation of water vapor, released into the droplet, enhances its burning rate, whereas later there is a water-evaporation period, during which the water vapor reduces the flame temperature suffciently to extinguish the flame. Recent methanol droplet-combustion experiments in ambient environments diluted with carbon dioxide, conducted in the Combustion Integrated Rack on the International Space Station (ISS), as a part of the FLEX project, provided a method to delineate the water-absorption period from the water-evaporation period using video images of flame intensity. These were obtained using an ultra-violet camera that captures the OH* radical emission at 310 nm wavelength and a color camera that captures visible flame emission. These results are compared with results of ground-based tests in the Zero Gravity Facility at the NASA Glenn Research Center which employed smaller droplets in argon-diluted environments. A simplified theoretical model developed earlier correlates the transition time at which water absorption ends and evaporation starts. The model results are shown to agree reasonably well with experiment.

  8. Fat-soluble vitamin intestinal absorption: absorption sites in the intestine and interactions for absorption.

    PubMed

    Goncalves, Aurélie; Roi, Stéphanie; Nowicki, Marion; Dhaussy, Amélie; Huertas, Alain; Amiot, Marie-Josèphe; Reboul, Emmanuelle

    2015-04-01

    The interactions occurring at the intestinal level between the fat-soluble vitamins A, D, E and K (FSVs) are poorly documented. We first determined each FSV absorption profile along the duodenal-colonic axis of mouse intestine to clarify their respective absorption sites. We then investigated the interactions between FSVs during their uptake by Caco-2 cells. Our data show that vitamin A was mostly absorbed in the mouse proximal intestine, while vitamin D was absorbed in the median intestine, and vitamin E and K in the distal intestine. Significant competitive interactions for uptake were then elucidated among vitamin D, E and K, supporting the hypothesis of common absorption pathways. Vitamin A also significantly decreased the uptake of the other FSVs but, conversely, its uptake was not impaired by vitamins D and K and even promoted by vitamin E. These results should be taken into account, especially for supplement formulation, to optimise FSV absorption. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Spectral Interferences Manganese (Mn) - Europium (Eu) Lines in X-Ray Fluorescence Spectrometry Spectrum

    NASA Astrophysics Data System (ADS)

    Tanc, Beril; Kaya, Mustafa; Gumus, Lokman; Kumral, Mustafa

    2016-04-01

    X-ray fluorescence (XRF) spectrometry is widely used for quantitative and semi quantitative analysis of many major, minor and trace elements in geological samples. Some advantages of the XRF method are; non-destructive sample preparation, applicability for powder, solid, paste and liquid samples and simple spectrum that are independent from chemical state. On the other hand, there are some disadvantages of the XRF methods such as poor sensitivity for low atomic number elements, matrix effect (physical matrix effects, such as fine versus course grain materials, may impact XRF performance) and interference effect (the spectral lines of elements may overlap distorting results for one or more elements). Especially, spectral interferences are very significant factors for accurate results. In this study, semi-quantitative analyzed manganese (II) oxide (MnO, 99.99%) was examined. Samples were pelleted and analyzed with XRF spectrometry (Bruker S8 Tiger). Unexpected peaks were obtained at the side of the major Mn peaks. Although sample does not contain Eu element, in results 0,3% Eu2O3 was observed. These result can occur high concentration of MnO and proximity of Mn and Eu lines. It can be eliminated by using correction equation or Mn concentration can confirm with other methods (such as Atomic absorption spectroscopy). Keywords: Spectral Interferences; Manganese (Mn); Europium (Eu); X-Ray Fluorescence Spectrometry Spectrum.

  10. INFRARED SPECTRUM OF POTASSIUM-CATIONIZED TRIETHYLPHOSPHATE GENERATED USING TANDEM MASS SPECTROMETRY AND INFRARED MULTIPLE PHOTON DISSOCIATION

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gary S. Groenewold; Christopher M. Leavitt; Ryan P. Dain

    2009-09-01

    Tandem mass spectrometry and wavelength selective infrared photodissociation was used to generate an infrared spectrum of gas-phase triethylphosphate cationized by attachment of K+. Prominent absorptions were observed in the region of 900 to 1300 cm-1 that are characteristic of phosphate P=O and P-O-R stretches. The relative positions and intensities of the IR absorptions were reproduced well by density functional theory (DFT) calculations performed using the B3LYP functional and the 6-31+g(d), 6-311+g(d,p) and 6-311++G(3df,2pd) basis sets. Because of good correspondence between experiment and theory for the cation, DFT was then used to generate a theoretical spectrum for neutral triethylphosphate, which inmore » turn accurately reproduces the IR spectrum of the neat liquid when solvent effects are included in the calculations.« less

  11. Electrically tunable coherent optical absorption in graphene with ion gel.

    PubMed

    Thareja, Vrinda; Kang, Ju-Hyung; Yuan, Hongtao; Milaninia, Kaveh M; Hwang, Harold Y; Cui, Yi; Kik, Pieter G; Brongersma, Mark L

    2015-03-11

    We demonstrate electrical control over coherent optical absorption in a graphene-based Salisbury screen consisting of a single layer of graphene placed in close proximity to a gold back reflector. The screen was designed to enhance light absorption at a target wavelength of 3.2 μm by using a 600 nm-thick, nonabsorbing silica spacer layer. An ionic gel layer placed on top of the screen was used to electrically gate the charge density in the graphene layer. Spectroscopic reflectance measurements were performed in situ as a function of gate bias. The changes in the reflectance spectra were analyzed using a Fresnel based transfer matrix model in which graphene was treated as an infinitesimally thin sheet with a conductivity given by the Kubo formula. The analysis reveals that a careful choice of the ionic gel layer thickness can lead to optical absorption enhancements of up to 5.5 times for the Salisbury screen compared to a suspended sheet of graphene. In addition to these absorption enhancements, we demonstrate very large electrically induced changes in the optical absorption of graphene of ∼3.3% per volt, the highest attained so far in a device that features an atomically thick active layer. This is attributable in part to the more effective gating achieved with the ion gel over the conventional dielectric back gates and partially by achieving a desirable coherent absorption effect linked to the presence of the thin ion gel that boosts the absorption by 40%.

  12. Determination of dietary cadmium-induced metallothioneins in rabbit kidneys and cadmium in metallothioneins by anion-exchange high-performance liquid chromatography coupled with graphite furnace atomic absorption spectrometry.

    PubMed

    Peng, S; Shan, X Q; Zheng, Y; Jin, L Z; Xu, W B

    1991-12-06

    A rapid method is described for the determination of dietary cadmium-induced metallothioneins (MTs) in rabbit kidneys by anion-exchange high-performance liquid chromatography. Rabbit kidney MT-I and MT-II were eluted at ca. 15.0 and 18.8 min, respectively, from a DEAE-5PW anion-exchange column with a Tris-HCl buffer (0.01-0.25 M, pH 8.6) and detected by ultraviolet absorbance at 254 nm. A standard calibration curve was constructed using purified standard MT isoforms, which demonstrated an excellent linear correlation between UV absorbance peak heights and the amounts of MT isoforms. Feeding a dose of cadmium for some days resulted in an increase in MT concentrations in rabbit kidneys, but not in the livers. The cadmium concentrations in MT-I and MT-II elutions were determined by graphite furnace atomic absorption spectrometry. MT-I and MT-II showed some differences associated with the oral intake of cadmium. Dietary cadmium also caused zinc to accumulate in kidneys to some extent. The effects of dietary oleic acid on the synthesis of MTs were also studied. Based on the method of standard additions, the recovery of MTs exceeded 93% and replicated injection of samples yielded a relative standard deviation of 2.4% at an MT level of 280 micrograms/g.

  13. Quantitative mass spectrometry: an overview

    NASA Astrophysics Data System (ADS)

    Urban, Pawel L.

    2016-10-01

    Mass spectrometry (MS) is a mainstream chemical analysis technique in the twenty-first century. It has contributed to numerous discoveries in chemistry, physics and biochemistry. Hundreds of research laboratories scattered all over the world use MS every day to investigate fundamental phenomena on the molecular level. MS is also widely used by industry-especially in drug discovery, quality control and food safety protocols. In some cases, mass spectrometers are indispensable and irreplaceable by any other metrological tools. The uniqueness of MS is due to the fact that it enables direct identification of molecules based on the mass-to-charge ratios as well as fragmentation patterns. Thus, for several decades now, MS has been used in qualitative chemical analysis. To address the pressing need for quantitative molecular measurements, a number of laboratories focused on technological and methodological improvements that could render MS a fully quantitative metrological platform. In this theme issue, the experts working for some of those laboratories share their knowledge and enthusiasm about quantitative MS. I hope this theme issue will benefit readers, and foster fundamental and applied research based on quantitative MS measurements. This article is part of the themed issue 'Quantitative mass spectrometry'.

  14. Detector absorptivity measuring method and apparatus

    NASA Technical Reports Server (NTRS)

    Sheets, R. E. (Inventor)

    1976-01-01

    A method and apparatus for measuring the absorptivity of a radiation detector by making the detector an integral part of a cavity radiometer are described. By substituting the detector for the surface of the cavity upon which the radiation first impinges a comparison is made between the quantity of radiation incident upon the detector and the quantity reflected from the detector. The difference between the two is a measurement of the amount of radiation absorbed by the detector.

  15. Imaging Mass Spectrometry on the Nanoscale with Cluster Ion Beams

    DOE PAGES

    Winograd, Nicholas

    2014-12-02

    Imaging with cluster secondary ion mass spectrometry (SIMS) is reaching a mature level of development. When, using a variety of molecular ion projectiles to stimulate desorption, 3-dimensional imaging with the selectivity of mass spectrometry can now be achieved with submicrometer spatial resolution and <10 nm depth resolution. In this Perspective, stock is taken regarding what it will require to routinely achieve these remarkable properties. Some issues include the chemical nature of the projectile, topography formation, differential erosion rates, and perhaps most importantly, ionization efficiency. Shortcomings of existing instrumentation are also noted. One key part of this discussion involves speculation onmore » how best to resolve these issues.« less

  16. Imaging Mass Spectrometry on the Nanoscale with Cluster Ion Beams

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Winograd, Nicholas

    Imaging with cluster secondary ion mass spectrometry (SIMS) is reaching a mature level of development. When, using a variety of molecular ion projectiles to stimulate desorption, 3-dimensional imaging with the selectivity of mass spectrometry can now be achieved with submicrometer spatial resolution and <10 nm depth resolution. In this Perspective, stock is taken regarding what it will require to routinely achieve these remarkable properties. Some issues include the chemical nature of the projectile, topography formation, differential erosion rates, and perhaps most importantly, ionization efficiency. Shortcomings of existing instrumentation are also noted. One key part of this discussion involves speculation onmore » how best to resolve these issues.« less

  17. Enhancement of the grafting performance and of the water absorption of cassava starch graft copolymer by gamma radiation

    NASA Astrophysics Data System (ADS)

    Kiatkamjornwong, Suda; Meechai, Nispa

    1997-06-01

    Enhancement of the gamma radiation grafting of acrylonitrile onto gelatinized cassava starch was investigated. Infrared spectrometry was used to follow the chemical changes in the grafting reaction and from saponification. The saponified starch- g-PAN (HSPAN) was then characterized in terms of grafting parameters to provide a guide for the optimum total dose (kGy) and the appropriate ratio of starch/acrylonitrile for a fixed dose rate of 2.5 × 10 -1 kGy/min. Other dose rates were also carried out to obtain the appropriate result of grafting copolymerization and of water absorption. A thin aluminium foil, covering the inner wall of the reaction vessel, was found to be far more effective than any other metal films in the enhancement of the grafting reaction and the water absorption as well. Nitric acid in the medium increases the grafting yield and the water absorption. Methyl ether hydroquinone inhibitor was evaluated for its ability to increase homopolymerization and decrease graft reaction. When styrene was used as a comonomer, it hampered the grafting of acrylonitrile onto starch backbone. The water absorption capacity was improved by freeze-drying the HSPAN. The treatment of the HSPAN with aluminium trichloride hexahydrate was found to enhance the degree of wicking, but to decrease the water absorbency.

  18. Comparative absorption, distribution, and excretion of titanium dioxide and zinc oxide nanoparticles after repeated oral administration.

    PubMed

    Cho, Wan-Seob; Kang, Byeong-Cheol; Lee, Jong Kwon; Jeong, Jayoung; Che, Jeong-Hwan; Seok, Seung Hyeok

    2013-03-26

    The in vivo kinetics of nanoparticles is an essential to understand the hazard of nanoparticles. Here, the absorption, distribution, and excretion patterns of titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles following oral administration were evaluated. Nanoparticles were orally administered to rats for 13 weeks (7 days/week). Samples of blood, tissues (liver, kidneys, spleen, and brain), urine, and feces were obtained at necropsy. The level of Ti or Zn in each sample was measured using inductively coupled plasma-mass spectrometry. TiO₂ nanoparticles had extremely low absorption, while ZnO nanoparticles had higher absorption and a clear dose-response curve. Tissue distribution data showed that TiO₂ nanoparticles were not significantly increased in sampled organs, even in the group receiving the highest dose (1041.5 mg/kg body weight). In contrast, Zn concentrations in the liver and kidney were significantly increased compared with the vehicle control. ZnO nanoparticles in the spleen and brain were minimally increased. Ti concentrations were not significantly increased in the urine, while Zn levels were significantly increased in the urine, again with a clear dose-response curve. Very high concentrations of Ti were detected in the feces, while much less Zn was detected in the feces. Compared with TiO₂ nanoparticles, ZnO nanoparticles demonstrated higher absorption and more extensive organ distribution when administered orally. The higher absorption of ZnO than TiO₂ nanoparticles might be due to the higher dissolution rate in acidic gastric fluid, although more thorough studies are needed.

  19. Optical absorption in disordered monolayer molybdenum disulfide

    NASA Astrophysics Data System (ADS)

    Ekuma, C. E.; Gunlycke, D.

    2018-05-01

    We explore the combined impact of sulfur vacancies and electronic interactions on the optical properties of monolayer MoS2. First, we present a generalized Anderson-Hubbard Hamiltonian that accounts for both randomly distributed sulfur vacancies and the presence of dielectric screening within the material. Second, we parametrize this energy-dependent Hamiltonian from first-principles calculations based on density functional theory and the Green's function and screened Coulomb (GW) method. Third, we apply a first-principles-based many-body typical medium method to determine the single-particle electronic structure. Fourth, we solve the Bethe-Salpeter equation to obtain the charge susceptibility χ with its imaginary part being related to the absorbance A . Our results show that an increased vacancy concentration leads to decreased absorption both in the band continuum and from exciton states within the band gap. We also observe increased absorption below the band-gap threshold and present an expression, which describes Lifshitz tails, in excellent qualitative agreement with our numerical calculations. This latter increased absorption in the 1.0 -2.5 eV range makes defect engineering of potential interest for solar cell applications.

  20. Determination of BROMATE AT PARTS-PER-TRILLION LEVELS BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY WITH NEGATIVE CHEMICAL IONIZATION

    EPA Science Inventory

    The ozonation of bromide-containing source waters produces bromate as a class 2B carcinogenic disinfection by-product. The present work describes the determination of bromate by gas chromatography-negative chemical ionization mass spectrometry (GC-NCIMS) following a bromate react...

  1. Determination of lead, cadmium and mercury in blood for assessment of environmental exposure: A comparison between inductively coupled plasma mass spectrometry and atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Palmer, Christopher D.; Lewis, Miles E.; Geraghty, Ciaran M.; Barbosa, Fernando; Parsons, Patrick J.

    2006-08-01

    A biomonitoring method for the determination of Pb, Cd, and Hg at background levels in whole blood by inductively coupled plasma-mass spectrometry is described. While this method was optimized for assessing Pb, Cd and Hg at environmental levels, it also proved suitable for assessing concentrations associated with occupational exposure. The method requires as little as 200 μl of blood that is diluted 1 + 49 for direct analysis in the inductively coupled plasma-mass spectrometer. Method performance is compared to well-established AAS methods. Initial method validation was accomplished using National Institute of Standards and Technology (NIST) Standard Reference Material 966, Toxic Metals in Bovine Blood. Method detection limits (3s) are 0.05 μg dl - 1 for Pb, 0.09 μg l - 1 for Cd; and 0.17 μg l - 1 for Hg. Repeatability ranged from 1.4% to 2.8% for Pb; 3% to 10% for Cd; and 2.6% to 8.8% for Hg. In contrast, AAS method detection limits were 1 μg dl - 1 , 0.54 μg l - 1 , and 0.6 μg l - 1 , for Pb, Cd, and Hg, respectively. Further performance assessments were conducted over a 2-year period via participation in four international External Quality Assessment Schemes (EQAS) operated specifically for toxic metals in blood. This includes schemes operated by (a) the New York State Department of Health's Wadsworth Center, Albany, NY, USA (b) L'Institut National de Santé Publique du Québec, Centre de Toxicologie du Québec, Canada, (c) Friedrich-Alexander University, Erlangen, Germany, and (d) the University of Surrey, Guildford, UK Trace Elements scheme. The EQAS data reflect analytical performance for blind samples analyzed independently by both inductively coupled plasma-mass spectrometry and AAS methods.

  2. Intercalation of IR absorber into layered double hydroxides: Preparation, thermal stability and selective IR absorption

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhu, Haifeng; Tang, Pinggui; Feng, Yongjun, E-mail: yjfeng@mail.buct.edu.cn

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer PMIDA anions were intercalated into Mg{sub 2}Al-NO{sub 3} LDH by anion-exchange method. Black-Right-Pointing-Pointer The prepared material has highly selective IR absorption property in 9-11 {mu}m. Black-Right-Pointing-Pointer The obtained material has practical applications as heat-retaining additive. -- Abstract: N-phosphonomethyl aminodiacetic acid (PMIDA) was intercalated into the interlayer spacing of layered double hydroxides (LDH) by an anion-exchange method. The intercalated LDHs were characterized by various techniques such as powder X-ray diffraction (XRD), FT-IR spectroscopy, elemental analysis and simultaneous thermogravimetric and mass spectrometry (TG-MS) in details. The results show the formation of Mg{sub 2}Al-PMIDA LDH based on the expansion of d-spacingmore » from 0.89 nm to 1.22 nm and the disappearance of the characteristic IR absorption band at 1384 cm{sup -1} for NO{sub 3}{sup -} anions. The incorporation of Mg{sub 2}Al-PMIDA LDH into the low density polyethylene (LDPE) as an additive enhances the selectivity of IR absorption in the main wavelength region 9-11 {mu}m for radiant heat loss at night. Mg{sub 2}Al-PMIDA LDH as a heat-retaining additive has practical application in agricultural plastic films.« less

  3. Cluster secondary ion mass spectrometry microscope mode mass spectrometry imaging.

    PubMed

    Kiss, András; Smith, Donald F; Jungmann, Julia H; Heeren, Ron M A

    2013-12-30

    Microscope mode imaging for secondary ion mass spectrometry is a technique with the promise of simultaneous high spatial resolution and high-speed imaging of biomolecules from complex surfaces. Technological developments such as new position-sensitive detectors, in combination with polyatomic primary ion sources, are required to exploit the full potential of microscope mode mass spectrometry imaging, i.e. to efficiently push the limits of ultra-high spatial resolution, sample throughput and sensitivity. In this work, a C60 primary source was combined with a commercial mass microscope for microscope mode secondary ion mass spectrometry imaging. The detector setup is a pixelated detector from the Medipix/Timepix family with high-voltage post-acceleration capabilities. The system's mass spectral and imaging performance is tested with various benchmark samples and thin tissue sections. The high secondary ion yield (with respect to 'traditional' monatomic primary ion sources) of the C60 primary ion source and the increased sensitivity of the high voltage detector setup improve microscope mode secondary ion mass spectrometry imaging. The analysis time and the signal-to-noise ratio are improved compared with other microscope mode imaging systems, all at high spatial resolution. We have demonstrated the unique capabilities of a C60 ion microscope with a Timepix detector for high spatial resolution microscope mode secondary ion mass spectrometry imaging. Copyright © 2013 John Wiley & Sons, Ltd.

  4. Displacement-dispersive liquid-liquid microextraction based on solidification of floating organic drop of trace amounts of palladium in water and road dust samples prior to graphite furnace atomic absorption spectrometry determination.

    PubMed

    Ghanbarian, Maryam; Afzali, Daryoush; Mostafavi, Ali; Fathirad, Fariba

    2013-01-01

    A new displacement-dispersive liquid-liquid microextraction method based on the solidification of floating organic drop was developed for separation and preconcentration of Pd(ll) in road dust and aqueous samples. This method involves two steps of dispersive liquid-liquid microextraction based on solidification. In Step 1, Cu ions react with diethyldithiocarbamate (DDTC) to form Cu-DDTC complex, which is extracted by dispersive liquid-liquid microextraction based on a solidification procedure using 1-undecanol (extraction solvent) and ethanol (dispersive solvent). In Step 2, the extracted complex is first dispersed using ethanol in a sample solution containing Pd ions, then a dispersive liquid-liquid microextraction based on a solidification procedure is performed creating an organic drop. In this step, Pd(ll) replaces Cu(ll) from the pre-extracted Cu-DDTC complex and goes into the extraction solvent phase. Finally, the Pd(ll)-containing drop is introduced into a graphite furnace using a microsyringe, and Pd(ll) is determined using atomic absorption spectrometry. Several factors that influence the extraction efficiency of Pd and its subsequent determination, such as extraction and dispersive solvent type and volume, pH of sample solution, centrifugation time, and concentration of DDTC, are optimized.

  5. The Mysterious 6565 Å Absorption Feature of the Galactic Halo

    NASA Astrophysics Data System (ADS)

    Sethi, Shiv K.; Shchekinov, Yuri; Nath, Biman B.

    2017-12-01

    We consider various possible scenarios to explain the recent observation of what has been called a broad Hα absorption in our Galactic halo, with peak optical depth τ ≃ 0.01 and equivalent width W≃ 0.17 \\mathringA . We show that the absorbed feature cannot arise from the circumgalactic and ISM Hα absorption. As the observed absorption feature is quite broad ({{Δ }}λ ≃ 30 \\mathringA ), we also consider CNO lines that lie close to Hα as possible alternatives to explain the feature. We show that such lines could also not account for the observed feature. Instead, we suggest that it could arise from diffuse interstellar bands (DIBs) carriers or polyaromatic hydrocarbons (PAHs) absorption. While we identify several such lines close to the Hα transition, we are unable to determine the molecule responsible for the observed feature, partly because of selection effects that prevent us from identifying DIBs/PAHs features close to Hα using local observations. Deep integration of a few extragalactic sources with high spectral resolution might allow us to distinguish between different possible explanations.

  6. Intestinal absorption of strontium chloride in healthy volunteers: pharmacokinetics and reproducibility

    PubMed Central

    SIPS, A. J. A. M.; van der VIJGH, W. J. F.; BARTO, R.; NETELENBOS, J. C.

    1996-01-01

    1The absorption kinetics of orally administered strontium chloride and its reproducibility were investigated in healthy volunteers after administering strontium either under fasting conditions (study I, n=8) or in combination with a standardized meal (study II, n=8). Each subject received strontium orally at day 0, 14, and 28 and intravenously at day 42. The study was performed as part of a project in which a simple clinical test for measuring intestinal calcium absorption is being developed, based on the use of stable strontium as a marker. 2Plasma strontium concentration–time curves were analysed by noncompartment analysis and a four compartment disposition model. Within a volunteer each oral curve was fitted simultaneously with the intravenous curve, by which means a two segment model for absorption was revealed. 3Mean absolute bioavailability of strontium was 25% without a meal and 19% with a meal, whereas the intraindividual variation was 24% and 20%, respectively. 4Various limited sampling absorption parameters were determined in order to select a potential test parameter for measuring intestinal calcium absorption using strontium as a marker. Fractional absorption at 4 h (Fc240), obtained after co-ingestion of strontium with a meal, appeared to be the best test parameter, because it represented bioavailability well (r=0.90). PMID:8799520

  7. The absorption budget of fresh biomass burning aerosol from realistic laboratory fires

    NASA Astrophysics Data System (ADS)

    Wagner, N. L.; Adler, G. A.; Franchin, A.; Lamb, K.; Manfred, K.; Middlebrook, A. M.; Selimovic, V.; Schwarz, J. P.; Washenfelder, R. A.; Womack, C.; Yokelson, R. J.

    2017-12-01

    Wildfires are expected to increase globally due to climate change. The smoke from these wildfires has a highly uncertain radiative effect, largely due to the lack of detailed understanding of its optical properties. As part of the NOAA FIREX project, we have measured the optical properties of smoke primarily from laboratory burning of North American fuels at the Missoula Fire Sciences Laboratory. Here, we present a budget of the aerosol absorption from a portion of the laboratory fires. The total aerosol absorption was measured with photoacoustic spectrometers (PAS) at four wavelengths (405 nm, 532 nm, 660 nm, 870 nm) spanning the visible spectral region. The aerosol absorption is attributed to black carbon which absorbs broadly across the visible and ultraviolet (UV) spectral region and brown carbon (BrC) which absorbs in the blue and UV spectral regions. Then aerosol absorption measurements are compared with measurements of refractory black carbon (rBC) concentration by laser induced incandescence (SP2) and measurements of BrC concentration from a particle-into-liquid sampler coupled to a liquid absorption cell (BrC-PILS). Periodically, a thermodenuder was inserted upstream of all of the instruments to constrain the relationship between aerosol volatility and absorption. We synthesize these measurements to constrain the various contributors to total absorption including effects of lensing on rBC absorption, and of BrC that is not volatilized in the thermodenuder.

  8. Modeling of Plutonium Ionization Probabilities for Use in Nuclear Forensic Analysis by Resonance Ionization Mass Spectrometry

    DTIC Science & Technology

    2016-12-01

    masses collide, they form a supercritical mass . Criticality refers to the neutron population within the system. A critical system is one that can...Spectrometry, no. 242, pp. 161–168, 2005. [9] S. Raeder, “Trace analysis of actinides in the environment by means of resonance ionization mass ...first ionization potential of actinide elements by resonance ionization mass spectrometry.” Spectrochimica Acta part B: Atomic Spectroscopy. vol. 52

  9. Absorption Voltages and Insulation Resistance in Ceramic Capacitors with Cracks

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2014-01-01

    Time dependence of absorption voltages (V(sub abs)) in different types of low-voltage X5R and X7R ceramic capacitors was monitored for a maximum duration of hundred hours after polarization. To evaluate the effect of mechanical defects on V(sub abs)), cracks in the dielectric were introduced either mechanically or by thermal shock. The maximum absorption voltage, time to roll-off, and the rate of voltage decrease are shown to depend on the crack-related leakage currents and insulation resistance in the parts. A simple model that is based on the Dow equivalent circuit for capacitors with absorption has been developed to assess the insulation resistance of capacitors. Standard measurements of the insulation resistance, contrary to the measurements based on V(sub abs)), are not sensitive to the presence of mechanical defects and fail to reveal capacitors with cracks.

  10. The facilitated component of intestinal glucose absorption

    PubMed Central

    Kellett, George L

    2001-01-01

    Over the last decade, a debate has developed about the mechanism of the passive or ‘diffusive’ component of intestinal glucose absorption and, indeed, whether it even exists. Pappenheimer and colleagues have proposed that paracellular solvent drag contributes a passive component, which, at high concentrations of sugars similar to those in the jejunal lumen immediately after a meal, is severalfold greater than the active component mediated by the Na+-glucose cotransporter SGLT1. On the other hand, Ferraris & Diamond maintain that the kinetics of glucose absorption can be explained solely in terms of SGLT1 and that a passive or paracellular component plays little, if any, part. Recently, we have provided new evidence that the passive component of glucose absorption exists, but is in fact facilitated since it is mediated by the rapid, glucose-dependent activation and recruitment of the facilitative glucose transporter GLUT2 to the brush-border membrane; regulation involves a protein kinase C (PKC)-dependent pathway activated by glucose transport through SGLT1 and also involves mitogen-activated protein kinase (MAP kinase) signalling pathways. This topical review seeks to highlight the significant points of the debate, to show how our proposals on GLUT2 impact on different aspects of the debate and to look at the regulatory events that are likely to be involved in the short-term regulation of sugar absorption during the assimilation of a meal. PMID:11251042

  11. Forensic Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Hoffmann, William D.; Jackson, Glen P.

    2015-07-01

    Developments in forensic mass spectrometry tend to follow, rather than lead, the developments in other disciplines. Examples of techniques having forensic potential born independently of forensic applications include ambient ionization, imaging mass spectrometry, isotope ratio mass spectrometry, portable mass spectrometers, and hyphenated chromatography-mass spectrometry instruments, to name a few. Forensic science has the potential to benefit enormously from developments that are funded by other means, if only the infrastructure and personnel existed to adopt, validate, and implement the new technologies into casework. Perhaps one unique area in which forensic science is at the cutting edge is in the area of chemometrics and the determination of likelihood ratios for the evaluation of the weight of evidence. Such statistical techniques have been developed most extensively for ignitable-liquid residue analyses and isotope ratio analysis. This review attempts to capture the trends, motivating forces, and likely impact of developing areas of forensic mass spectrometry, with the caveat that none of this research is likely to have any real impact in the forensic community unless: (a) The instruments developed are turned into robust black boxes with red and green lights for positives and negatives, respectively, or (b) there are PhD graduates in the workforce who can help adopt these sophisticated techniques.

  12. Regression Model for Light Weight and Crashworthiness Enhancement Design of Automotive Parts in Frontal CAR Crash

    NASA Astrophysics Data System (ADS)

    Bae, Gihyun; Huh, Hoon; Park, Sungho

    This paper deals with a regression model for light weight and crashworthiness enhancement design of automotive parts in frontal car crash. The ULSAB-AVC model is employed for the crash analysis and effective parts are selected based on the amount of energy absorption during the crash behavior. Finite element analyses are carried out for designated design cases in order to investigate the crashworthiness and weight according to the material and thickness of main energy absorption parts. Based on simulations results, a regression analysis is performed to construct a regression model utilized for light weight and crashworthiness enhancement design of automotive parts. An example for weight reduction of main energy absorption parts demonstrates the validity of a regression model constructed.

  13. Scattered light and accuracy of the cross-section measurements of weak absorptions: Gas and liquid phase UV absorption cross sections of CH3CFCl2

    NASA Technical Reports Server (NTRS)

    Fahr, A.; Braun, W.; Kurylo, M. J.

    1993-01-01

    Ultraviolet absorption cross sections of CH3CFCl2(HCFC-141b) were determined in the gas phase (190-260 nm) and liquid phase (230-260 mm) at 298 K. The liquid phase absorption cross sections were then converted into accurate gas phase values using a previously described procedure. It has been demonstrated that scattered light from the shorter-wavelength region (as little as several parts per thousand) can seriously compromise the absorption cross-section measurement, particularly at longer wavelengths where cross sections are low, and can be a source of discrepancies in the cross sections of weakly absorbing halocarbons reported in the literature. A modeling procedure was developed to assess the effect of scattered light on the measured absorption cross section in our experiments, thereby permitting appropriate corrections to be made on the experimental values. Modeled and experimental results were found to be in good agreement. Experimental results from this study were compared with other available determinations and provide accurate input for calculating the atmospheric lifetime of HCFC-141b.

  14. Dendrimer pre-treatment enhances the skin permeation of chlorhexidine digluconate: Characterisation by in vitro percutaneous absorption studies and Time-of-Flight Secondary Ion Mass Spectrometry.

    PubMed

    Holmes, Amy M; Scurr, David J; Heylings, Jon R; Wan, Ka-Wai; Moss, Gary P

    2017-06-15

    Skin penetration and localisation of chlorhexidine digluconate (CHG) within the skin have been investigated in order to better understand and optimise the delivery using a nano polymeric delivery system of this topically-applied antimicrobial drug. Franz-type diffusion cell studies using in vitro porcine skin and tape stripping procedures were coupled with Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) to visualise the skin during various treatments with CHG and polyamidoamine dendrimers (PAMAM). Pre-treatment of the skin with PAMAM dendrimers significantly increased the amount and depth of permeation of CHG into the skin in vitro. The effect observed was not concentration dependant in the range 0.5-10mM PAMAM. This could be important in terms of the efficiency of treatment of bacterial infection in the skin. It appears that the mechanism of enhancement is due to the PAMAM dendrimer disrupting skin barrier lipid conformation or by occluding the skin surface. Franz-type diffusion cell experiments are complimented by the detailed visualisation offered by the semi-quantitative ToF-SIMS method which provides excellent benefits in terms of sensitivity and fragment ion specificity. This allows a more accurate depth profile of chlorhexidine permeation within the skin to be obtained and potentially affords the opportunity to map the co-localisation of permeants with skin structures, thus providing a greater ability to characterise skin absorption and to understand the mechanism of permeation, providing opportunities for new and more effective therapies. Copyright © 2017. Published by Elsevier B.V.

  15. Statistical modelling coupled with LC-MS analysis to predict human upper intestinal absorption of phytochemical mixtures.

    PubMed

    Selby-Pham, Sophie N B; Howell, Kate S; Dunshea, Frank R; Ludbey, Joel; Lutz, Adrian; Bennett, Louise

    2018-04-15

    A diet rich in phytochemicals confers benefits for health by reducing the risk of chronic diseases via regulation of oxidative stress and inflammation (OSI). For optimal protective bio-efficacy, the time required for phytochemicals and their metabolites to reach maximal plasma concentrations (T max ) should be synchronised with the time of increased OSI. A statistical model has been reported to predict T max of individual phytochemicals based on molecular mass and lipophilicity. We report the application of the model for predicting the absorption profile of an uncharacterised phytochemical mixture, herein referred to as the 'functional fingerprint'. First, chemical profiles of phytochemical extracts were acquired using liquid chromatography mass spectrometry (LC-MS), then the molecular features for respective components were used to predict their plasma absorption maximum, based on molecular mass and lipophilicity. This method of 'functional fingerprinting' of plant extracts represents a novel tool for understanding and optimising the health efficacy of plant extracts. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Application of chitosan and its N-heterocyclic derivatives for preconcentration of noble metal ions and their determination using atomic absorption spectrometry.

    PubMed

    Azarova, Yu A; Pestov, A V; Ustinov, A Yu; Bratskaya, S Yu

    2015-12-10

    Chitosan and its N-heterocyclic derivatives N-2-(2-pyridyl)ethylchitosan (2-PEC), N-2-(4-pyridyl) ethylchitosan (4-PEC), and N-(5-methyl-4-imidazolyl) methylchitosan (IMC) have been applied in group preconcentration of gold, platinum, and palladium for subsequent determination by atomic absorption spectroscopy (AAS) in solutions with high background concentrations of iron and sodium ions. It has been shown that the sorption mechanism, which was elucidated by XPS, significantly influences the sorption capacity of materials, the efficiency of metal ions elution after preconcentration, and, as a result, the accuracy of metal determination by AAS. We have shown that native chitosan was not suitable for preconcentration of Au(III), if the elution step was used as a part of the analysis scheme. The group preconcentration of Au(III), Pd(II), and Pt(IV) with subsequent quantitative elution using 0.1M HCl/1M thiourea solution was possible only on IMC and 4-PEC. Application of IMC for analysis of the national standard quartz ore sample proved that gold could be accurately determined after preconcentration/elution with the recovery above 80%. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. X-ray Spectrometry.

    ERIC Educational Resources Information Center

    Markowicz, Andrzej A.; Van Grieken, Rene E.

    1984-01-01

    Provided is a selective literature survey of X-ray spectrometry from late 1981 to late 1983. Literature examined focuses on: excitation (photon and electron excitation and particle-induced X-ray emission; detection (wavelength-dispersive and energy-dispersive spectrometry); instrumentation and techniques; and on such quantitative analytical…

  18. Absorption of Solar Radiation by the Cloudy Atmosphere Interpretations of Collocated Aircraft Measurements

    NASA Technical Reports Server (NTRS)

    Valero, Francisco P. J.; Cess, Robert D.; Zhang, Minghua; Pope, Shelly K.; Bucholtz, Anthony; Bush, Brett; Vitko, John, Jr.

    1997-01-01

    As part of the Atmospheric Radiation Measurement (ARM) Enhanced Shortwave Experiment (ARESE), we have obtained and analyzed measurements made from collocated aircraft of the absorption of solar radiation within the atmospheric column between the two aircraft. The measurements were taken during October 1995 at the ARM site in Oklahoma. Relative to a theoretical radiative transfer model, we find no evidence for excess solar absorption in the clear atmosphere and significant evidence for its existence in the cloudy atmosphere. This excess cloud solar absorption appears to occur in both visible (0.224-0.68 microns) and near-infrared (0.68-3.30 microns) spectral regions, although not at 0.5 microns for the visible contribution, and it is shown to be true absorption rather than an artifact of sampling errors caused by measuring three-dimensional clouds.

  19. Characterization of dissolved organic matter in Dongjianghu Lake by UV-visible absorption spectroscopy with multivariate analysis.

    PubMed

    Zhu, Yanzhong; Song, Yonghui; Yu, Huibin; Liu, Ruixia; Liu, Lusan; Lv, Chunjian

    2017-08-08

    UV-visible absorption spectroscopy coupled with principal component analysis (PCA) and hierarchical cluster analysis (HCA) was applied to characterize spectroscopic components, detect latent factors, and investigate spatial variations of dissolved organic matter (DOM) in a large-scale lake. Twelve surface water samples were collected from Dongjianghu Lake in China. DOM contained lignin and quinine moieties, carboxylic acid, microbial products, and aromatic and alkyl groups, which in the northern part of the lake was largely different from the southern part. Fifteen spectroscopic indices were deduced from the absorption spectra to indicate molecular weight or humification degree of DOM. The northern part of the lake presented the smaller molecular weight or the lower humification degree of DOM than the southern part. E 2/4 , E 3/4 , E 2/3 , and S 2 were latent factors of characterizing the molecular weight of DOM, while E 2/5 , E 3/5 , E 2/6 , E 4/5 , E 3/6 , and A 2/1 were latent factors of evaluating the humification degree of DOM. The UV-visible absorption spectroscopy combined with PCA and HCA may not only characterize DOM fractions of lakes, but may be transferred to other types of waterscape.

  20. Simple hollow fiber renewal liquid membrane extraction method for pre-concentration of Cd(II) in environmental samples and detection by flame atomic absorption spectrometry.

    PubMed

    Carletto, Jeferson Schneider; Luciano, Raquel Medeiros; Bedendo, Gizelle Cristina; Carasek, Eduardo

    2009-04-06

    A hollow fiber renewal liquid membrane (HFRLM) extraction method to determine cadmium (II) in water samples using Flame Atomic Absorption Spectrometry (FAAS) was developed. Ammonium O,O-diethyl dithiophosphate (DDTP) was used to complex cadmium (II) in an acid medium to obtain a neutral hydrophobic complex (ML(2)). The organic solvent introduced to the sample extracts this complex from the aqueous solution and carries it over the poly(dimethylsiloxane) (PDMS) membrane, that had their walls previously filled with the same organic solvent. The organic solvent is solubilized inside the PDMS membrane, leading to a homogeneous phase. The complex strips the lumen of the membrane where, at higher pH, the complex Cd-DDTP is broken down and cadmium (II) is released into the stripping phase. EDTA was used to complex the cadmium (II), helping to trap the analyte in the stripping phase. A multivariate procedure was used to optimize the studied variables. The optimized variables were: sample (donor phase) pH 3.25, DDTP concentration 0.05% (m/v), stripping (acceptor phase) pH 8.75, EDTA concentration 1.5x10(-2) mol L(-1), extraction temperature 40 degrees C, extraction time 40 min, a solvent mixture N-butyl acetate and hexane (60/40%, v/v) with a volume of 100 microL, and addition of ammonium sulfate to saturate the sample. The sample volume used was 20 mL and the stripping volume was 165 microL. The analyte enrichment factor was 120, limit of detection (LOD) 1.3 microg L(-1), relative standard deviation (RSD) 5.5% and the working linear range 2-30 microg L(-1).

  1. History of mass spectrometry at the Olympic Games.

    PubMed

    Hemmersbach, Peter

    2008-07-01

    Mass spectrometry has played a decisive role in doping analysis and doping control in human sport for almost 40 years. The standard of qualitative and quantitative determinations in body fluids has always attracted maximum attention from scientists. With its unique sensitivity and selectivity properties, mass spectrometry provides state-of-the-art technology in analytical chemistry. Both anti-doping organizations and the athletes concerned expect the utmost endeavours to prevent false-positive and false-negative results of the analytical evidence. The Olympic Games play an important role in international sport today and are milestones for technical development in doping analysis. This review of the part played by mass spectrometry in doping control from Munich 1972 to Beijing 2008 Olympics gives an overview of how doping analysis has developed and where we are today. In recognizing the achievements made towards effective doping control, it is of the utmost importance to applaud the joint endeavours of the World Anti-Doping Agency, the International Olympic Committee, the international federations and national anti-doping agencies to combat doping. Advances against the misuse of prohibited substances and methods, which are performance-enhancing, dangerous to health and violate the spirit of sport, can be achieved only if all the stakeholders work together. Copyright 2008 John Wiley & Sons, Ltd.

  2. Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations for solvent-based carbon capture. Part 2: Chemical absorption across a wetted wall column: Original Research Article: Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Chao; Xu, Zhijie; Lai, Kevin

    The first part of this paper (Part 1) presents a numerical model for non-reactive physical mass transfer across a wetted wall column (WWC). In Part 2, we improved the existing computational fluid dynamics (CFD) model to simulate chemical absorption occurring in a WWC as a bench-scale study of solvent-based carbon dioxide (CO2) capture. To generate data for WWC model validation, CO2 mass transfer across a monoethanolamine (MEA) solvent was first measured on a WWC experimental apparatus. The numerical model developed in this work has the ability to account for both chemical absorption and desorption of CO2 in MEA. In addition,more » the overall mass transfer coefficient predicted using traditional/empirical correlations is conducted and compared with CFD prediction results for both steady and wavy falling films. A Bayesian statistical calibration algorithm is adopted to calibrate the reaction rate constants in chemical absorption/desorption of CO2 across a falling film of MEA. The posterior distributions of the two transport properties, i.e., Henry’s constant and gas diffusivity in the non-reacting nitrous oxide (N2O)/MEA system obtained from Part 1 of this study, serves as priors for the calibration of CO2 reaction rate constants after using the N2O/CO2 analogy method. The calibrated model can be used to predict the CO2 mass transfer in a WWC for a wider range of operating conditions.« less

  3. Simultaneous determination of V, Ni and Fe in fuel fly ash using solid sampling high resolution continuum source graphite furnace atomic absorption spectrometry.

    PubMed

    Cárdenas Valdivia, A; Vereda Alonso, E; López Guerrero, M M; Gonzalez-Rodriguez, J; Cano Pavón, J M; García de Torres, A

    2018-03-01

    A green and simple method has been proposed in this work for the simultaneous determination of V, Ni and Fe in fuel ash samples by solid sampling high resolution continuum source graphite furnace atomic absorption spectrometry (SS HR CS GFAAS). The application of fast programs in combination with direct solid sampling allows eliminating pretreatment steps, involving minimal manipulation of sample. Iridium treated platforms were applied throughout the present study, enabling the use of aqueous standards for calibration. Correlation coefficients for the calibration curves were typically better than 0.9931. The concentrations found in the fuel ash samples analysed ranged from 0.66% to 4.2% for V, 0.23-0.7% for Ni and 0.10-0.60% for Fe. Precision (%RSD) were 5.2%, 10.0% and 9.8% for V, Ni and Fe, respectively, obtained as the average of the %RSD of six replicates of each fuel ash sample. The optimum conditions established were applied to the determination of the target analytes in fuel ash samples. In order to test the accuracy and applicability of the proposed method in the analysis of samples, five ash samples from the combustion of fuel in power stations, were analysed. The method accuracy was evaluated by comparing the results obtained using the proposed method with the results obtained by ICP OES previous acid digestion. The results showed good agreement between them. The goal of this work has been to develop a fast and simple methodology that permits the use of aqueous standards for straightforward calibration and the simultaneous determination of V, Ni and Fe in fuel ash samples by direct SS HR CS GFAAS. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Determination of copper and mercury in phosphate fertilizers employing direct solid sampling analysis and high resolution continuum source graphite furnace atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    de Oliveira Souza, Sidnei; François, Luciane Luiza; Borges, Aline Rocha; Vale, Maria Goreti Rodrigues; Araujo, Rennan Geovanny Oliveira

    2015-12-01

    The present study proposes the determination of copper and mercury in phosphate fertilizers by direct solid sampling analysis (SS) employing high resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). For Cu determination, two analytical lines were used: 327.3960 nm and 249.2146 nm. Hg determination was carried out on the line 253.6521 nm and 100 μg KMnO4 was used as chemical modifier. The optimal pyrolysis temperature for Cu determination was 1300 °C. Atomization temperatures for Cu and Hg were 2400 and 1100 °C, respectively. External calibration with aqueous standard solutions was adopted for both elements. The limits of quantification (LoQs) and characteristic mass (m0) obtained for Cu determination were 0.4 μg g- 1 and 1.12 ng, respectively, on line 249.2146 nm, and 64 μg g- 1 and 25 pg on 327.3960 nm. For mercury, LoQ and m0 were 4.8 ng g- 1 and 39 pg, respectively. The accuracy of the proposed methods was confirmed by the analysis of standard reference material (SRM) of Trace Elements in Multi-Nutrient Fertilizer (SRM NIST 695). The precision expressed as relative standard deviation (RSD), was better than 8.2% for Hg and 7.7% for the Cu (n = 5), considered satisfactory for microanalysis in solid sample. Four fertilizer samples acquired in commercial establishments in the city of Salvador, Bahia, Brazil, were analyzed. The optimized analytical methods were simple, fast, accurate, precise and free of spectral interferences for the determination of Cu and Hg in phosphate fertilizer samples by SS-HR-CS GF AAS, avoiding the dissolution of the sample, the use of harmful reagents and the generation of residues.

  5. Ion Imprinted Polymer for Preconcentration and Determination of Ultra-Trace Cadmium, Employing Flow Injection Analysis with Thermo Spray Flame Furnace Atomic Absorption Spectrometry.

    PubMed

    do Lago, Ayla Campos; Marchioni, Camila; Mendes, Tássia Venga; Wisniewski, Célio; Fadini, Pedro Sergio; Luccas, Pedro Orival

    2016-11-01

    This work proposes a preconcentration method using an ion imprinted polymer (IIP) for determination of cadmium, in several samples, employing a mini-column filled with the polymer coupled into a flow injection analysis system with detection by thermospray flame furnace atomic absorption spectrometry (FIA-TS-FF-AAS). The polymer was synthesized via bulk using methacrylic acid and vinylimidazole as a functional monomer. For the FIA system initial assessment, the variables: pH, eluent concentration and buffer concentration were studied, employing a 23 full factorial design. To obtain the optimum values for each significant variable, a Doehlert matrix was employed. After the optimization conditions as: pH 5.8, eluent (HNO3) concentration of 0.48 mol L -1 and buffer concentration of 0.01 mol L -1 , were adopted. The proposed method showed a linear response in the range of 0.081-10.0 μg L -1 , limits detection and quantification of 0.024 and 0.081 μg L -1 , respectively; preconcentration factor of 165, consumptive index of 0.06 mL, concentration efficiency 132 min -1 , and frequency of readings equal to 26 readings h -1 The accuracy was checked by analysis of certified reference materials for trace metals and recovery tests. The obtained results were in agreement with 95% confidence level (t-test). The method was adequate to apply in samples of: jewelry (earrings) (2.38 ± 0.28 μg kg -1 ), black tea (1.09 ± 0.15 μg kg -1 ), green tea (3.85 ± 0.13 μg kg -1 ), cigarette tobacco (38.27 ± 0.22 μg kg -1 ), and hair (0.35 ± 0.02 μg kg -1 ). © The Author(s) 2016.

  6. Measurements of Soot Mass Absorption Coefficients from 300 to 660 nm

    NASA Astrophysics Data System (ADS)

    Renbaum-Wolff, Lindsay; Fisher, Al; Helgestad, Taylor; Lambe, Andrew; Sedlacek, Arthur; Smith, Geoffrey; Cappa, Christopher; Davidovits, Paul; Onasch, Timothy; Freedman, Andrew

    2016-04-01

    Soot, a product of incomplete combustion, plays an important role in the earth's climate system through the absorption and scattering of solar radiation. In particular, the assumed mass absorption coefficient (MAC) of soot and its variation with wavelength presents a significant uncertainty in the calculation of radiative forcing in global climate change models. As part of the fourth Boston College/Aerodyne soot properties measurement campaign, we have measured the mass absorption coefficient of soot produced by an inverted methane diffusion flame over a spectral range of 300-660 nm using a variety of optical absorption techniques. Extinction and absorption were measured using a dual cavity ringdown photoacoustic spectrometer (CRD-PAS, UC Davis) at 405 nm and 532 nm. Scattering and extinction were measured using a CAPS PMssa single scattering albedo monitor (Aerodyne) at 630 nm; the absorption coefficient was determined by subtraction. In addition, the absorption coefficients in 8 wavelength bands from 300 to 660 nm were measured using a new broadband photoacoustic absorption monitor (UGA). Soot particle mass was quantified using a centrifugal particle mass analyzer (CPMA, Cambustion), mobility size with a scanning mobility particle sizer (SMPS, TSI) and soot concentration with a CPC (Brechtel). The contribution of doubly charged particles to the sample mass was determined using a Single Particle Soot Photometer (DMT). Over a mass range of 1-8 fg, corresponding to differential mobility diameters of ~150 nm to 550 nm, the value of the soot MAC proved to be independent of mass for all wavelengths. The wavelength dependence of the MAC was best fit to a power law with an Absorption Ångstrom Coefficient slightly greater than 1.

  7. 69. INTERIOR VIEW OF THE ABSORPTION TOWER BUILDING, ABSORPTION TOWER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    69. INTERIOR VIEW OF THE ABSORPTION TOWER BUILDING, ABSORPTION TOWER UNDER CONSTRUCTION. (DATE UNKNOWN). - United States Nitrate Plant No. 2, Reservation Road, Muscle Shoals, Muscle Shoals, Colbert County, AL

  8. MASS SPECTROMETRY IN ENVIRONMENTAL SCIENCES

    EPA Science Inventory

    This review covers applications of mass spectrometry to the environmental sciences. From the early applications of mass spectrometry to environmental research in the 1960s and 1970s, mass spectrometry has played an important role in aiding our understanding of environmental poll...

  9. Complex Resonance Absorption Structure in the X-Ray Spectrum of IRAS 13349+2438

    NASA Technical Reports Server (NTRS)

    Sako, M.; Kahn, S. M.; Behar, E.; Kaastra, J. S.; Brinkman, A. C.; Boller, Th.; Puchnarewicz, E. M.; Starling, R.; Liedahl, D. A.; Clavel, J.

    2000-01-01

    The luminous infrared-loud quasar IRAS 13349+2438 was observed with the XMM - Newton Observatory as part of the Performance Verification program. The spectrum obtained by the Reflection Grating Spectrometer (RGS) exhibits broad (FWHM - 1400 km/s) absorption lines from highly ionized elements including hydrogen- and helium-like carbon, nitrogen, oxygen, and neon, and several iron L - shell ions (Fe XVII - XX). Also shown in the spectrum is the first astrophysical detection of a broad absorption feature around lambda = 16 - 17 A identified as an unresolved transition array (UTA) of 2p - 3d inner-shell absorption by iron M-shell ions in a much cooler medium; a feature that might be misidentified as an O VII edge when observed with moderate resolution spectrometers. No absorption edges are clearly detected in the spectrum. We demonstrate that the RGS spectrum of IRAS 13349+2438 exhibits absorption lines from two distinct regions, one of which is tentatively associated with the medium that produces the optical/UV reddening.

  10. In silico predictions of gastrointestinal drug absorption in pharmaceutical product development: application of the mechanistic absorption model GI-Sim.

    PubMed

    Sjögren, Erik; Westergren, Jan; Grant, Iain; Hanisch, Gunilla; Lindfors, Lennart; Lennernäs, Hans; Abrahamsson, Bertil; Tannergren, Christer

    2013-07-16

    Oral drug delivery is the predominant administration route for a major part of the pharmaceutical products used worldwide. Further understanding and improvement of gastrointestinal drug absorption predictions is currently a highly prioritized area of research within the pharmaceutical industry. The fraction absorbed (fabs) of an oral dose after administration of a solid dosage form is a key parameter in the estimation of the in vivo performance of an orally administrated drug formulation. This study discloses an evaluation of the predictive performance of the mechanistic physiologically based absorption model GI-Sim. GI-Sim deploys a compartmental gastrointestinal absorption and transit model as well as algorithms describing permeability, dissolution rate, salt effects, partitioning into micelles, particle and micelle drifting in the aqueous boundary layer, particle growth and amorphous or crystalline precipitation. Twelve APIs with reported or expected absorption limitations in humans, due to permeability, dissolution and/or solubility, were investigated. Predictions of the intestinal absorption for different doses and formulations were performed based on physicochemical and biopharmaceutical properties, such as solubility in buffer and simulated intestinal fluid, molecular weight, pK(a), diffusivity and molecule density, measured or estimated human effective permeability and particle size distribution. The performance of GI-Sim was evaluated by comparing predicted plasma concentration-time profiles along with oral pharmacokinetic parameters originating from clinical studies in healthy individuals. The capability of GI-Sim to correctly predict impact of dose and particle size as well as the in vivo performance of nanoformulations was also investigated. The overall predictive performance of GI-Sim was good as >95% of the predicted pharmacokinetic parameters (C(max) and AUC) were within a 2-fold deviation from the clinical observations and the predicted plasma AUC

  11. In vivo percutaneous absorption of boron as boric acid, borax, and disodium octaborate tetrahydrate in humans: a summary.

    PubMed

    Wester, R C; Hui, X; Maibach, H I; Bell, K; Schell, M J; Northington, D J; Strong, P; Culver, B D

    1998-01-01

    Literature from the first half of this century reports concern for toxicity from topical use of boric acid, but assessment of percutaneous absorption has been impaired by lack of analytical sensitivity. Analytical methods in this study included inductively coupled plasma-mass spectrometry, which now allows quantitation of percutaneous absorption of 10B in 10B-enriched boric acid, borax, and disodium octaborate tetrahydrate (DOT) in biological matrices. This made it possible, in the presence of comparatively large natural dietary boron intakes for the in vivo segment of this study, to quantify the boron passing through skin. Human volunteers were dosed with 10B-enriched boric acid, 5.0%, borax, 5.0%, or disodium octaborate tetrahydrate, 10% in aqueous solutions. Urinalysis, for boron and changes in boron isotope ratios, was used to measure absorption. Boric acid in vivo percutaneous absorption was 0.226 (SD = 0.125) mean percent dose, with flux and permeability constant (Kp) calculated at 0.009 microg/cm2/h and 1.9 x 10(-7) cm/h, respectively. Borax absorption was 0.210 (SD = 0.194) mean percent dose, with flux and Kp calculated at 0.009 microg/cm2/h and 1.8 x 10(-7) cm/h, respectively. DOT absorption was 0.122 (SD = 0.108) mean percent, with flux and Kp calculated at 0.01 microg/cm2/h and 1.0 x 10(-7) cm/h, respectively. Pretreatment with the potential skin irritant 2% sodium lauryl sulfate had no effect on boron skin absorption. These in vivo results show that percutaneous absorption of boron, as boric acid, borax, and disodium octaborate tetrahydrate, through intact human skin is low and is significantly less than the average daily dietary intake. This very low boron skin absorption makes it apparent that, for the borates tested, the use of gloves to prevent systemic uptake is unnecessary. These findings do not apply to abraded or otherwise damaged skin.

  12. Imaging mass spectrometry statistical analysis.

    PubMed

    Jones, Emrys A; Deininger, Sören-Oliver; Hogendoorn, Pancras C W; Deelder, André M; McDonnell, Liam A

    2012-08-30

    Imaging mass spectrometry is increasingly used to identify new candidate biomarkers. This clinical application of imaging mass spectrometry is highly multidisciplinary: expertise in mass spectrometry is necessary to acquire high quality data, histology is required to accurately label the origin of each pixel's mass spectrum, disease biology is necessary to understand the potential meaning of the imaging mass spectrometry results, and statistics to assess the confidence of any findings. Imaging mass spectrometry data analysis is further complicated because of the unique nature of the data (within the mass spectrometry field); several of the assumptions implicit in the analysis of LC-MS/profiling datasets are not applicable to imaging. The very large size of imaging datasets and the reporting of many data analysis routines, combined with inadequate training and accessible reviews, have exacerbated this problem. In this paper we provide an accessible review of the nature of imaging data and the different strategies by which the data may be analyzed. Particular attention is paid to the assumptions of the data analysis routines to ensure that the reader is apprised of their correct usage in imaging mass spectrometry research. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. X-ray absorption spectroscopy: EXAFS (Extended X-ray Absorption Fine Structure) and XANES (X-ray Absorption Near Edge Structure)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Alp, E.E.; Mini, S.M.; Ramanathan, M.

    1990-04-01

    The x-ray absorption spectroscopy (XAS) had been an essential tool to gather spectroscopic information about atomic energy level structure in the early decades of this century. It has also played an important role in the discovery and systematization of rare-earth elements. The discovery of synchrotron radiation in 1952, and later the availability of broadly tunable synchrotron based x-ray sources have revitalized this technique since the 1970's. The correct interpretation of the oscillatory structure in the x-ray absorption cross-section above the absorption edge by Sayers et. al. has transformed XAS from a spectroscopic tool to a structural technique. EXAFS (Extended X-raymore » Absorption Fine Structure) yields information about the interatomic distances, near neighbor coordination numbers, and lattice dynamics. An excellent description of the principles and data analysis techniques of EXAFS is given by Teo. XANES (X-ray Absorption Near Edge Structure), on the other hand, gives information about the valence state, energy bandwidth and bond angles. Today, there are about 50 experimental stations in various synchrotrons around the world dedicated to collecting x-ray absorption data from the bulk and surfaces of solids and liquids. In this chapter, we will give the basic principles of XAS, explain the information content of essentially two different aspects of the absorption process leading to EXAFS and XANES, and discuss the source and samples limitations.« less

  14. Experimental analysis of energy absorption behaviour of Al-tube filled with pumice lightweight concrete under axial loading condition

    NASA Astrophysics Data System (ADS)

    Rajak, D. K.; Deshpande, P. G.; Kumaraswamidhas, L. A.

    2017-08-01

    This Paper aimed at experimental investigation of compressive behaviour of square tube filled with pumice lightweight concrete (PLC). Square section of 20×20×30 mm is investigated, which is the backbone structure. The compression deformation result shows the better folding mechanism, displacement value, and energy absorption. PLC concrete filled with aluminium thin-wall tubes has been revealed superior energy absorption capacity (EAC) under low strain rate at room temperature. Superior EAC resulted as a result of mutual deformation benefit between aluminium section and PLC is also analysed. PLC was characterised by Fourier Transform Infrared (FTIR) and Field Emission Scanning Electron Microscopy (FESEM), and Energy Dispersive X-ray Spectrometry (EDX) analysis for better understanding of material behaviour. Individual and comparative load bearing graphs is logged for better prospective of analysing. Novel approach aimed at validation of porous lightweight concrete for better lightweight EA filler material.

  15. Gas-Phase Dopant-Induced Conformational Changes Monitored with Transversal Modulation Ion Mobility Spectrometry.

    PubMed

    Meyer, Nicole Andrea; Root, Katharina; Zenobi, Renato; Vidal-de-Miguel, Guillermo

    2016-02-16

    The potential of a Transversal Modulation Ion Mobility Spectrometry (TMIMS) instrument for protein analysis applications has been evaluated. The Collision Cross Section (CCS) of cytochrome c measured with the TMIMS is in agreement with values reported in the literature. Additionally, it enables tandem IMS-IMS prefiltration in dry gas and in vapor doped gas. The chemical specificity of the different dopants enables interesting studies on the structure of proteins as CCS changed strongly depending on the specific dopant. Hexane produced an unexpectedly high CCS shift, which can be utilized to evaluate the exposure of hydrophobic parts of the protein. Alcohols produced higher shifts with a dual behavior: an increase in CCS due to vapor uptake at specific absorption sites, followed by a linear shift typical for unspecific and unstable vapor uptake. The molten globule +8 shows a very specific transition. Initially, its CCS follows the trend of the compact folded states, and then it rapidly increases to the levels of the unfolded states. This strong variation suggests that the +8 charge state undergoes a dopant-induced conformational change. Interestingly, more sterically demanding alcohols seem to unfold the protein more effectively also in the gas phase. This study shows the capabilities of the TMIMS device for protein analysis and how tandem IMS-IMS with dopants could provide better understanding of the conformational changes of proteins.

  16. Absorption heat pump for space applications

    NASA Technical Reports Server (NTRS)

    Nguyen, Tuan; Simon, William E.; Warrier, Gopinath R.; Woramontri, Woranun

    1993-01-01

    In the first part, the performance of the Absorption Heat Pump (AHP) with water-sulfuric acid and water-magnesium chloride as two new refrigerant-absorbent fluid pairs was investigated. A model was proposed for the analysis of the new working pairs in a heat pump system, subject to different temperature lifts. Computer codes were developed to calculate the Coefficient of Performance (COP) of the system with the thermodynamic properties of the working fluids obtained from the literature. The study shows the potential of water-sulfuric acid as a satisfactory replacement for water-lithium bromide in the targeted temperature range. The performance of the AHP using water-magnesium chloride as refrigerant-absorbent pair does not compare well with those obtained using water-lithium bromide. The second part concentrated on the design and testing of a simple ElectroHydrodynamic (EHD) Pump. A theoretical design model based on continuum electromechanics was analyzed to predict the performance characteristics of the EHD pump to circulate the fluid in the absorption heat pump. A numerical method of solving the governing equations was established to predict the velocity profile, pressure - flow rate relationship and efficiency of the pump. The predicted operational characteristics of the EHD pump is comparable to that of turbomachinery hardware; however, the overall efficiency of the electromagnetic pump is much lower. An experimental investigation to verify the numerical results was conducted. The pressure - flow rate performance characteristics and overall efficiency of the pump obtained experimentally agree well with the theoretical model.

  17. Determination of serum aluminum by electrothermal atomic absorption spectrometry: A comparison between Zeeman and continuum background correction systems

    NASA Astrophysics Data System (ADS)

    Kruger, Pamela C.; Parsons, Patrick J.

    2007-03-01

    Excessive exposure to aluminum (Al) can produce serious health consequences in people with impaired renal function, especially those undergoing hemodialysis. Al can accumulate in the brain and in bone, causing dialysis-related encephalopathy and renal osteodystrophy. Thus, dialysis patients are routinely monitored for Al overload, through measurement of their serum Al. Electrothermal atomic absorption spectrometry (ETAAS) is widely used for serum Al determination. Here, we assess the analytical performances of three ETAAS instruments, equipped with different background correction systems and heating arrangements, for the determination of serum Al. Specifically, we compare (1) a Perkin Elmer (PE) Model 3110 AAS, equipped with a longitudinally (end) heated graphite atomizer (HGA) and continuum-source (deuterium) background correction, with (2) a PE Model 4100ZL AAS equipped with a transversely heated graphite atomizer (THGA) and longitudinal Zeeman background correction, and (3) a PE Model Z5100 AAS equipped with a HGA and transverse Zeeman background correction. We were able to transfer the method for serum Al previously established for the Z5100 and 4100ZL instruments to the 3110, with only minor modifications. As with the Zeeman instruments, matrix-matched calibration was not required for the 3110 and, thus, aqueous calibration standards were used. However, the 309.3-nm line was chosen for analysis on the 3110 due to failure of the continuum background correction system at the 396.2-nm line. A small, seemingly insignificant overcorrection error was observed in the background channel on the 3110 instrument at the 309.3-nm line. On the 4100ZL, signal oscillation was observed in the atomization profile. The sensitivity, or characteristic mass ( m0), for Al at the 309.3-nm line on the 3110 AAS was found to be 12.1 ± 0.6 pg, compared to 16.1 ± 0.7 pg for the Z5100, and 23.3 ± 1.3 pg for the 4100ZL at the 396.2-nm line. However, the instrumental detection limits (3

  18. Charge-transfer optical absorption mechanism of DNA:Ag-nanocluster complexes

    NASA Astrophysics Data System (ADS)

    Longuinhos, R.; Lúcio, A. D.; Chacham, H.; Alexandre, S. S.

    2016-05-01

    Optical properties of DNA:Ag-nanoclusters complexes have been successfully applied experimentally in Chemistry, Physics, and Biology. Nevertheless, the mechanisms behind their optical activity remain unresolved. In this work, we present a time-dependent density functional study of optical absorption in DNA:Ag4. In all 23 different complexes investigated, we obtain new absorption peaks in the visible region that are not found in either the isolated Ag4 or isolated DNA base pairs. Absorption from red to green are predominantly of charge-transfer character, from the Ag4 to the DNA fragment, while absorption in the blue-violet range are mostly associated to electronic transitions of a mixed character, involving either DNA-Ag4 hybrid orbitals or intracluster orbitals. We also investigate the role of exchange-correlation functionals in the calculated optical spectra. Significant differences are observed between the calculations using the PBE functional (without exact exchange) and the CAM-B3LYP functional (which partly includes exact exchange). Specifically, we observe a tendency of charge-transfer excitations to involve purines bases, and the PBE spectra error is more pronounced in the complexes where the Ag cluster is bound to the purines. Finally, our results also highlight the importance of adding both the complementary base pair and the sugar-phosphate backbone in order to properly characterize the absorption spectrum of DNA:Ag complexes.

  19. Charge-transfer optical absorption mechanism of DNA:Ag-nanocluster complexes.

    PubMed

    Longuinhos, R; Lúcio, A D; Chacham, H; Alexandre, S S

    2016-05-01

    Optical properties of DNA:Ag-nanoclusters complexes have been successfully applied experimentally in Chemistry, Physics, and Biology. Nevertheless, the mechanisms behind their optical activity remain unresolved. In this work, we present a time-dependent density functional study of optical absorption in DNA:Ag_{4}. In all 23 different complexes investigated, we obtain new absorption peaks in the visible region that are not found in either the isolated Ag_{4} or isolated DNA base pairs. Absorption from red to green are predominantly of charge-transfer character, from the Ag_{4} to the DNA fragment, while absorption in the blue-violet range are mostly associated to electronic transitions of a mixed character, involving either DNA-Ag_{4} hybrid orbitals or intracluster orbitals. We also investigate the role of exchange-correlation functionals in the calculated optical spectra. Significant differences are observed between the calculations using the PBE functional (without exact exchange) and the CAM-B3LYP functional (which partly includes exact exchange). Specifically, we observe a tendency of charge-transfer excitations to involve purines bases, and the PBE spectra error is more pronounced in the complexes where the Ag cluster is bound to the purines. Finally, our results also highlight the importance of adding both the complementary base pair and the sugar-phosphate backbone in order to properly characterize the absorption spectrum of DNA:Ag complexes.

  20. Consistency of ARESE II Cloud Absorption Estimates and Sampling Issues

    NASA Technical Reports Server (NTRS)

    Oreopoulos, L.; Marshak, A.; Cahalan, R. F.; Lau, William K. M. (Technical Monitor)

    2002-01-01

    Data from three cloudy days (March 3, 21, 29, 2000) of the ARM Enhanced Shortwave Experiment II (ARESE II) were analyzed. Grand averages of broadband absorptance among three sets of instruments were compared. Fractional solar absorptances were approx. 0.21-0.22 with the exception of March 3 when two sets of instruments gave values smaller by approx. 0.03-0.04. The robustness of these values was investigated by looking into possible sampling problems with the aid of 500 nm spectral fluxes. Grand averages of 500 nm apparent absorptance cover a wide range of values for these three days, namely from a large positive (approx. 0.011) average for March 3, to a small negative (approximately -0.03) for March 21, to near zero (approx. 0.01) for March 29. We present evidence suggesting that a large part of the discrepancies among the three days is due to the different nature of clouds and their non-uniform sampling. Hence, corrections to the grand average broadband absorptance values may be necessary. However, application of the known correction techniques may be precarious due to the sparsity of collocated flux measurements above and below the clouds. Our analysis leads to the conclusion that only March 29 fulfills all requirements for reliable estimates of cloud absorption, that is, the presence of thick, overcast, homogeneous clouds.

  1. Diode Lasers and Practical Trace Analysis.

    ERIC Educational Resources Information Center

    Imasaka, Totaro; Nobuhiko, Ishibashi

    1990-01-01

    Applications of lasers to molecular absorption spectrometry, molecular fluorescence spectrometry, visible semiconductor fluorometry, atomic absorption spectrometry, and atomic fluorescence spectrometry are discussed. Details of the use of the frequency-doubled diode laser are provided. (CW)

  2. Continuous Flow Atmospheric Pressure Laser Desorption/Ionization Using a 6–7-µm-Band Mid-Infrared Tunable Laser for Biomolecular Mass Spectrometry

    PubMed Central

    Hiraguchi, Ryuji; Hazama, Hisanao; Senoo, Kenichirou; Yahata, Yukinori; Masuda, Katsuyoshi; Awazu, Kunio

    2014-01-01

    A continuous flow atmospheric pressure laser desorption/ionization technique using a porous stainless steel probe and a 6–7-µm-band mid-infrared tunable laser was developed. This ion source is capable of direct ionization from a continuous flow with a high temporal stability. The 6–7-µm wavelength region corresponds to the characteristic absorption bands of various molecular vibration modes, including O–H, C=O, CH3 and C–N bonds. Consequently, many organic compounds and solvents, including water, have characteristic absorption peaks in this region. This ion source requires no additional matrix, and utilizes water or acetonitrile as the solvent matrix at several absorption peak wavelengths (6.05 and 7.27 µm, respectively). The distribution of multiply-charged peptide ions is extremely sensitive to the temperature of the heated capillary, which is the inlet of the mass spectrometer. This ionization technique has potential for the interface of liquid chromatography/mass spectrometry (LC/MS). PMID:24937686

  3. Determination of Chromium(III), Chromium(VI), and Chromium(III) acetylacetonate in water by ion-exchange disk extraction/metal furnace atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Kamakura, Nao; Inui, Tetsuo; Kitano, Masaru; Nakamura, Toshihiro

    A new method for the separate determination of Chromium(III) (Cr(III)), Chromium(VI) (Cr(VI)), and Cr(III) acetylacetonate (Cr(acac)3) in water was developed using a cation-exchange extraction disk (CED) and an anion-exchange extraction disk (AED) combined with metal furnace atomic absorption spectrometry (MFAAS). A 100-mL water sample was adjusted to pH 5.6 and passed through the CED placed on the AED. Cr(acac)3 and Cr(III) were adsorbed on the CED, and Cr(VI) was adsorbed on the AED. The adsorbed Cr(acac)3 was eluted with 50 mL of carbon tetrachloride, followed by the elution of Cr(III) with 50 mL of 3 mol L- 1 nitric acid. Cr(VI) was eluted with 50 mL of 3 mol L- 1 nitric acid. The chemical species of Cr eluted from the CED with carbon tetrachloride was identified as Cr(acac)3 using infrared spectroscopy. The eluate of Cr(acac)3 was diluted to 100 mL with carbon tetrachloride, and those of Cr(III) and Cr(VI) were diluted to 100 mL with deionized water. All of the solutions were subsequently analyzed by MFAAS. The calibration curve for the Cr(acac)3 aqueous solutions exhibited good linearity in the range of 0.1 to 1 ng. The detection limit of Cr, which corresponded to three times the standard deviation (n = 10) of the blank values, was 20 pg. The recovery test for Cr(III), Cr(VI), and Cr(acac)3 exhibited desirable results (96.0%-107%) when 5 μg of each species (50 μg L- 1) was added to 100 mL water samples (i.e., tap water, rainwater, and bottled drinking water). In a humic acid solution, Cr(acac)3 was quantitatively recovered (103%), but Cr(III) and Cr(VI) exhibited poor recoveries (i.e., 84.8% and 78.4%, respectively).

  4. Viable, lyophilized lactobacilli do not increase iron absorption from a lactic acid-fermented meal in healthy young women, and no iron absorption occurs in the distal intestine.

    PubMed

    Bering, Stine; Sjøltov, Laila; Wrisberg, Seema S; Berggren, Anna; Alenfall, Jan; Jensen, Mikael; Højgaard, Liselotte; Tetens, Inge; Bukhave, Klaus

    2007-11-01

    Lactic acid-fermented foods have been shown to increase Fe absorption in human subjects, possibly by lowering pH, activation of phytases, production of organic acids, or by the viable lactic acid bacteria. In this study the effect of a heat-inactivated lactic acid-fermented oat gruel with and without added viable, lyophilized Lactobacillus plantarum 299v on non-haem Fe absorption was investigated. Furthermore, Fe absorption in the distal intestine was determined. In a randomized, double-blinded crossover trial eighteen healthy young women aged 22 (SD 3) years with low Fe status (serum ferritin < 30 microg/l) were served the two test gruels, extrinsically labelled with 59Fe and served with two enterocoated capsules (containing 55Fe(II) and 55Fe(III), respectively) designed to disintegrate in the ileum. The meals were consumed on two consecutive days, e.g. in the order AA followed by BB in a second period. Non-haem Fe absorption was determined from 59Fe whole-body retention and isotope activities in blood samples. The concentrations of Fe, lactate, phytate, and polyphenols, and the pH were similar in the heat-inactivated lactic acid-fermented oat gruels with and without added L. plantarum 299v, and no difference in Fe absorption was observed between the test gruels (1.4 and 1.3%, respectively). Furthermore, no absorption of Fe in the distal intestine was observed. In conclusion, addition of viable, lyophilized lactobacillus to a heat-inactivated lactic acid-fermented oat gruel does not affect Fe absorption, and no absorption seems to occur in the distal part of the intestine from low Fe bioavailability meals in these women.

  5. Energy-Dispersive Spectrometry from Then until Now: A Chronology of Innovation

    NASA Astrophysics Data System (ADS)

    Friel, John J.; Mott, Richard B.

    1998-11-01

    : As part of the Microbeam Analysis Society (MAS) symposium marking 30 years of energy-dispersive spectrometry (EDS), this article reviews many innovations in the field over those years. Innovations that added a capability previously not available to the microanalyst are chosen for further description. Included are innovations in both X-ray microanalysis and digital imaging using the EDS analyzer.

  6. Water Vapor Remote Sensing Techniques: Radiometry and Solar Spectrometry

    NASA Astrophysics Data System (ADS)

    Somieski, A.; Buerki, B.; Cocard, M.; Geiger, A.; Kahle, H.-G.

    The high variability of atmospheric water vapor content plays an important role in space geodesy, climatology and meteorology. Water vapor has a strong influence on transatmospheric satellite signals, the Earth's climate and thus the weather forecasting. Several remote sensing techniques have been developed for the determination of inte- grated precipitable water vapor (IPWV). The Geodesy and Geodynamics Lab (GGL) utilizes the methods of Water Vapor Radiometry and Solar Spectrometry to quantify the amount of tropospheric water vapor and its temporal variations. The Water Vapor Radiometer (WVR) measures the radiation intensity of the atmosphere in a frequency band ranging from 20 to 32 GHz. The Solar Atmospheric MOnitoring Spectrome- ter (SAMOS) of GGL is designed for high-resolution measurements of water vapor absorption lines using solar radiation. In the framework of the ESCOMPTE (ExpÊrience sur Site pour COntraindre les Mod- Éles de Pollution atmosphÊrique et de Transport d'Emissions) field campaign these instruments have been operated near Marseille in 2001. They have aquired a long time series of integrated precipitable water vapor content (IPWV). The accuracy of IPWV measured by WVR and SAMOS is 1 kg/m2. Furthermore meteorological data from radiosondes were used to calculate the IPWV in order to provide comparisons with the results of WVR and SAMOS. The methods of Water Vapor Radiometry and So- lar Spectrometry will be discussed and first preliminary results retrieved from WVR, SAMOS and radiosondes during the ESCOMPTE field campaign will be presented.

  7. Optimisation of flame parameters for simultaneous multi-element atomic absorption spectrometric determination of trace elements in rocks

    USGS Publications Warehouse

    Kane, J.S.

    1988-01-01

    A study is described that identifies the optimum operating conditions for the accurate determination of Co, Cu, Mn, Ni, Pb, Zn, Ag, Bi and Cd using simultaneous multi-element atomic absorption spectrometry. Accuracy was measured in terms of the percentage recoveries of the analytes based on certified values in nine standard reference materials. In addition to identifying optimum operating conditions for accurate analysis, conditions resulting in serious matrix interferences and the magnitude of the interferences were determined. The listed elements can be measured with acceptable accuracy in a lean to stoicheiometric flame at measurement heights ???5-10 mm above the burner.

  8. Measurement of Scattering and Absorption Cross Sections of Dyed Microspheres

    PubMed Central

    Gaigalas, Adolfas K; Choquette, Steven; Zhang, Yu-Zhong

    2013-01-01

    Measurements of absorbance and fluorescence emission were carried out on aqueous suspensions of polystyrene (PS) microspheres with a diameter of 2.5 µm using a spectrophotometer with an integrating sphere detector. The apparatus and the principles of measurements were described in our earlier publications. Microspheres with and without green BODIPY@ dye were measured. Placing the suspension inside an integrating sphere (IS) detector of the spectrophotometer yielded (after a correction for fluorescence emission) the absorbance (called A in the text) due to absorption by BODIPY@ dye inside the microsphere. An estimate of the absorbance due to scattering alone was obtained by subtracting the corrected BODIPY@ dye absorbance (A) from the measured absorbance of a suspension placed outside the IS detector (called A1 in the text). The absorption of the BODIPY@ dye inside the microsphere was analyzed using an imaginary index of refraction parameterized with three Gaussian-Lorentz functions. The Kramer-Kronig relation was used to estimate the contribution of the BODIPY@ dye to the real part of the microsphere index of refraction. The complex index of refraction, obtained from the analysis of A, was used to analyze the absorbance due to scattering ((A1- A) in the text). In practice, the analysis of the scattering absorbance, A1-A, and the absorbance, A, was carried out in an iterative manner. It was assumed that A depended primarily on the imaginary part of the microsphere index of refraction with the other parameters playing a secondary role. Therefore A was first analyzed using values of the other parameters obtained from a fit to the absorbance due to scattering, A1-A, with the imaginary part neglected. The imaginary part obtained from the analysis of A was then used to reanalyze A1-A, and obtain better estimates of the other parameters. After a few iterations, consistent estimates were obtained of the scattering and absorption cross sections in the wavelength region 300

  9. Fast determination of trace elements in organic fertilizers using a cup-horn reactor for ultrasound-assisted extraction and fast sequential flame atomic absorption spectrometry.

    PubMed

    Teixeira, Leonel Silva; Vieira, Heulla Pereira; Windmöller, Cláudia Carvalhinho; Nascentes, Clésia Cristina

    2014-02-01

    A fast and accurate method based on ultrasound-assisted extraction in a cup-horn sonoreactor was developed to determine the total content of Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn in organic fertilizers by fast sequential flame atomic absorption spectrometry (FS FAAS). Multivariate optimization was used to establish the optimal conditions for the extraction procedure. An aliquot containing approximately 120 mg of the sample was added to a 500 µL volume of an acid mixture (HNO3/HCl/HF, 5:3:3, v/v/v). After a few minutes, 500 µL of deionized water was added and eight samples were simultaneously sonicated for 10 min at 50% amplitude, allowing a sample throughput of 32 extractions per hour. The performance of the method was evaluated with a certified reference material of sewage sludge (CRM 029). The precision, expressed as the relative standard deviation, ranged from 0.58% to 5.6%. The recoveries of analytes were found to 100%, 109%, 96%, 92%, 101%, 104% and 102% for Cd, Cr, Cu, Mn, Ni, Pb and Zn, respectively. The linearity, limit of detection and limit of quantification were calculated and the values obtained were adequate for the quality control of organic fertilizers. The method was applied to the analysis of several commercial organic fertilizers and organic wastes used as fertilizers, and the results were compared with those obtained using the microwave digestion procedure. A good agreement was found between the results obtained by microwave and ultrasound procedures with recoveries ranging from 80.4% to 117%. Two organic waste samples were not in accordance with the Brazilian legislation regarding the acceptable levels of contaminants. © 2013 Published by Elsevier B.V.

  10. Speciation and determination of ultra trace amounts of inorganic tellurium in environmental water samples by dispersive liquid-liquid microextraction and electrothermal atomic absorption spectrometry.

    PubMed

    Najafi, Nahid Mashkouri; Tavakoli, Hamed; Alizadeh, Reza; Seidi, Shahram

    2010-06-18

    A simple and powerful method has been developed for the rapid and selective determination of Te(IV) and Te(VI), employing dispersive liquid-liquid microextraction combined with electrothermal atomic absorption spectrometry using palladium as permanent modifier. Under acidic conditions pH 1, only Te(IV) can form a complex with ammonium pyrrolidine dithiocarbamate (APDC) and therefore be extracted into fine droplets of carbon tetrachloride (extraction solvent) which are dispersed with ethanol into the water sample solution. After centrifugation, Te(IV) was determined in the sedimented organic phase while Te(VI) remained in the aqueous phase. Total inorganic tellurium was determined after the reduction of the Te(VI) to Te(IV). Te(VI) was calculated as the difference between the measured total inorganic tellurium and Te(IV) content. The effective parameters for improving the efficiency of microextraction process were investigated by using experimental and central composite designs. Under optimal conditions the enrichment factor was 125 and the calibration graph was linear in the range of 0.015-1 ng mL(-1) with detection limit and characteristic mass of 0.004 ng mL(-1) and 0.033 pg, respectively. The relative standard deviation for 0.5 ng mL(-1) of tellurium measurement was 3.6% (n=6) at ash and atomization temperature, 900 and 2600 degrees C, respectively. The recoveries of spiked Te(IV) and Te(VI) to the environmental water samples were 89.6-101.3% and 96.6-99.1%, respectively. The accuracy is also evaluated by applying the proposed method to certified reference material (NIST SRM 1643e), for which the result was in a good agreement with the certified values reported for this CRM (95% confidence level). 2010 Elsevier B.V. All rights reserved.

  11. The in vivo pharmacokinetics, tissue distribution and excretion investigation of mesaconine in rats and its in vitro intestinal absorption study using UPLC-MS/MS.

    PubMed

    Liu, Xiuxiu; Tang, Minghai; Liu, Taohong; Wang, Chunyan; Tang, Qiaoxin; Xiao, Yaxin; Yang, Ruixin; Chao, Ruobing

    2017-12-27

    1. Mesaconine, an ingredient from Aconitum carmichaelii Debx., has been proven to have cardiac effect. For further development and better pharmacological elucidation, the in vivo process and intestinal absorptive behavior of mesaconine should be investigated comprehensively. 2. An ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the quantitation of mesaconine in rat plasma, tissue homogenates, urine and feces to investigate the in vivo pharmacokinetic profiles, tissue distribution and excretion. The intestinal absorptive behavior of mesaconine was investigated using in vitro everted rat gut sac model. 3. Mesaconine was well distributed in tissues and a mass of unchanged form was detected in feces. It was difficultly absorbed into blood circulatory system after oral administration. The insufficient oral bioavailability of mesaconine may be mainly attributed to its low intestinal permeability due to a lack of lipophilicity. The absorption of mesaconine in rat's intestine is a first-order process with the passive diffusion mechanism.

  12. In vivo percutaneous absorption of boric acid, borax, and disodium octaborate tetrahydrate in humans compared to in vitro absorption in human skin from infinite and finite doses.

    PubMed

    Wester, R C; Hui, X; Hartway, T; Maibach, H I; Bell, K; Schell, M J; Northington, D J; Strong, P; Culver, B D

    1998-09-01

    Literature from the first half of this century report concern for toxicity from topical use of boric acid, but assessment of percutaneous absorption has been impaired by lack of analytical sensitivity. Analytical methods in this study included inductively coupled plasma-mass spectrometry which now allows quantitation of percutaneous absorption of 10B in 10B-enriched boric acid, borax, and disodium octaborate tetrahydrate (DOT) in biological matrices. This made it possible, in the presence of comparatively large natural dietary boron intakes for the in vivo segment of this study, to quantify the boron passing through skin. Human volunteers were dosed with 10B-enriched boric acid, 5.0%, borax, 5.0%, or disodium octaborate tetrahydrate, 10%, in aqueous solutions. Urinalysis, for boron and changes in boron isotope ratios, was used to measure absorption. Boric acid in vivo percutaneous absorption was 0.226 (SD = 0.125) mean percentage dose, with flux and permeability constant (Kp) calculated at 0.009 microgram/cm2/h and 1.9 x 10(-7) cm/h, respectively. Borax absorption was 0.210 (SD = 0.194) mean percentage of dose, with flux and Kp calculated at 0.009 microgram/cm2/h and 1.8 x 10(-7) cm/h, respectively. DOT absorption was 0.122 (SD = 0.108) mean percentage, with flux and Kp calculated at 0.01 microgram/cm2/h and 1.0 x 10(-7) cm/h, respectively. Pretreatment with the potential skin irritant 2% sodium lauryl sulfate had no effect on boron skin absorption. In vitro human skin percentage of doses of boric acid absorbed were 1.2 for a 0.05% solution, 0.28 for a 0.5% solution, and 0.70 for a 5.0% solution. These absorption amounts translated into flux values of, respectively, 0.25, 0.58, and 14.58 micrograms/cm2/h and permeability constants (Kp) of 5.0 x 10(-4), 1.2 x 10(-4), and 2.9 x 10(-4) cm/h for the 0.05, 0.5, and 5.0% solutions. The above in vitro doses were at infinite, 1000 microliters/cm2 volume. At 2 microliters/cm2 (the in vivo dosing volume), flux decreased some

  13. Can sample treatments based on advanced oxidation processes assisted by high-intensity focused ultrasound be used for toxic arsenic determination in human urine by flow-injection hydride-generation atomic absorption spectrometry?

    PubMed

    Correia, A; Galesio, M; Santos, H; Rial-Otero, R; Lodeiro, C; Oehmen, A; Conceição, Antonio C L; Capelo, J L

    2007-05-15

    Two advanced oxidation processes (AOPs), based on high-intensity focused ultrasound (HIFU), namely, KMnO(4)/HCl/HIFU and H(2)O(2)/HCl/HIFU are studied and compared for the determination of toxic arsenic in human urine [As(III)+As(V)+MMA+DMA] by flow-injection hydride-generation atomic absorption spectrometry (FI-HG-AAS). The KMnO(4)/HCl/HIFU procedure was found to be adequate for organic matter degradation in human urine. l-cysteine (letra minuscula) was used for As reduction to the trivalent state. The new procedure was assessed with seven urines certified in different As species. Results revealed that with KMnO(4)/HCl/HIFU plus l-cysteine the toxic arsenic can be accurately measured in human urine whilst the H(2)O(2)/HCl/HIFU procedure underestimates toxic As. DMA and MMA degradation in urine were observed, due to the effects of the ultrasonic field. Recoveries for As(III), As(V), MMA and DMA were within the certified ranges. Arsenobetaine was not degraded by the AOPs. The new procedure adheres well to the principles of analytical minimalism: (i) low reagent consumption, (ii) low reagent concentration, (iii) low waste production and (iv) low amount of time required for sample preparation and analysis.

  14. Femtosecond time-domain observation of atmospheric absorption in the near-infrared spectrum

    NASA Astrophysics Data System (ADS)

    Hammond, T. J.; Monchocé, Sylvain; Zhang, Chunmei; Brown, Graham G.; Corkum, P. B.; Villeneuve, D. M.

    2016-12-01

    As light propagates through a medium, absorption caused by electronic or rovibrational transitions is evident in the transmitted spectrum. The incident electromagnetic field polarizes the medium and the absorption is due to the imaginary part of the linear susceptibility. In the time domain, the field establishes a coherence in the medium that radiates out of phase with the initial field. This coherence can persist for tens of picoseconds in atmospheric molecules such as H2O . We propagate a few-cycle laser pulse centered at 1.8 μ m through the atmosphere and measure the long-lasting molecular coherence in the time domain by high-order harmonic cross correlation. The measured optical free-induction decay of the pulse is compared with a calculation based on the calculated rovibrational spectrum of H2O absorption.

  15. Glucose Absorption by the Bacillary Band of Trichuris muris

    PubMed Central

    Hansen, Michael; Nejsum, Peter; Mejer, Helena; Denwood, Matthew; Thamsborg, Stig M.

    2016-01-01

    Background A common characteristic of Trichuris spp. infections in humans and animals is the variable but low efficacy of single-dose benzimidazoles currently used in mass drug administration programmes against human trichuriasis. The bacillary band, a specialised morphological structure of Trichuris spp., as well as the unique partly intracellular habitat of adult Trichuris spp. may affect drug absorption and perhaps contribute to the low drug accumulation in the worm. However, the exact function of the bacillary band is still unknown. Methodology We studied the dependency of adult Trichuris muris on glucose and/or amino acids for survival in vitro and the absorptive function of the bacillary band. The viability of the worms was evaluated using a motility scale from 0 to 3, and the colorimetric assay Alamar Blue was utilised to measure the metabolic activity. The absorptive function of the bacillary band in living worms was explored using a fluorescent glucose analogue (6-NBDG) and confocal microscopy. To study the absorptive function of the bacillary band in relation to 6-NBDG, the oral uptake was minimised or excluded by sealing the oral cavity with glue and agarose. Principal Findings Glucose had a positive effect on both the motility (p < 0.001) and metabolic activity (p < 0.001) of T. muris in vitro, whereas this was not the case for amino acids. The 6-NBDG was observed in the pores of the bacillary band and within the stichocytes of the living worms, independent of oral sealing. Conclusions/Significance Trichuris muris is dependent on glucose for viability in vitro, and the bacillary band has an absorptive function in relation to 6-NBDG, which accumulates within the stichocytes. The absorptive function of the bacillary band calls for an exploration of its possible role in the uptake of anthelmintics, and as a potential anthelmintic target relevant for future drug development. PMID:27588682

  16. Glucose Absorption by the Bacillary Band of Trichuris muris.

    PubMed

    Hansen, Tina V A; Hansen, Michael; Nejsum, Peter; Mejer, Helena; Denwood, Matthew; Thamsborg, Stig M

    2016-09-01

    A common characteristic of Trichuris spp. infections in humans and animals is the variable but low efficacy of single-dose benzimidazoles currently used in mass drug administration programmes against human trichuriasis. The bacillary band, a specialised morphological structure of Trichuris spp., as well as the unique partly intracellular habitat of adult Trichuris spp. may affect drug absorption and perhaps contribute to the low drug accumulation in the worm. However, the exact function of the bacillary band is still unknown. We studied the dependency of adult Trichuris muris on glucose and/or amino acids for survival in vitro and the absorptive function of the bacillary band. The viability of the worms was evaluated using a motility scale from 0 to 3, and the colorimetric assay Alamar Blue was utilised to measure the metabolic activity. The absorptive function of the bacillary band in living worms was explored using a fluorescent glucose analogue (6-NBDG) and confocal microscopy. To study the absorptive function of the bacillary band in relation to 6-NBDG, the oral uptake was minimised or excluded by sealing the oral cavity with glue and agarose. Glucose had a positive effect on both the motility (p < 0.001) and metabolic activity (p < 0.001) of T. muris in vitro, whereas this was not the case for amino acids. The 6-NBDG was observed in the pores of the bacillary band and within the stichocytes of the living worms, independent of oral sealing. Trichuris muris is dependent on glucose for viability in vitro, and the bacillary band has an absorptive function in relation to 6-NBDG, which accumulates within the stichocytes. The absorptive function of the bacillary band calls for an exploration of its possible role in the uptake of anthelmintics, and as a potential anthelmintic target relevant for future drug development.

  17. Optical absorption, electron spin resonance, and electron spin echo studies of the photoionization of tetramethylbenzidine in cationic and anionic synthetic vesicles: comparison with analogous micellar systems

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, A.S.W.; Kevan, L.

    1983-09-07

    The photoionization of N,N,N',N'-tetramethylbenzidine (TMB) in dihexadecylphosphate anionic vesicles and in dioctadecyldimethylammonium chloride cationic vesicles has been studied by optical absorption and electron spin resonance in liquid and frozen solutions. The TMB cation has been observed to be stabilized in both types of vesicles. The photoionization efficiency is about twofold greater in the cationic vesicles compared to the anionic vesicles. Shifts in the optical absorption maximum between micellar and vesicle solutions indicate that TMB is in a less polar environment in the vesicle systems. Electron spin echo modulation spectrometry has been used to detect TMB cation-water interactions that are foundmore » to be weaker than in previously studied micellar solutions. This is consistent with the optical absorption results and with an asymmetric solubilization site for TMB and TMB/sup +/ within the vesicular structure. A new absorption in the photoionized vesicles is assigned to a nonparamagnetic diamine-diimine charge-transfer complex between two TMB cations in the same vesicle. This complex is not formed in micellar systems. 5 figures.« less

  18. Comparative analysis of sixteen flavonoids from different parts of Sophora flavescens Ait. by ultra high-performance liquid chromatography-tandem mass spectrometry.

    PubMed

    Weng, Zebin; Zeng, Fei; Zhu, Zhenhua; Qian, Dawei; Guo, Sheng; Wang, Hanqing; Duan, Jin-Ao

    2018-07-15

    The root of Sophora flavescens Ait. has long been used as a crude drug in China and other Asian countries for thousands of years. The quinolizidine alkaloids and flavonoids are considered as the main bioactive components in this plant. To determine the distribution and content of the flavonoids in different organs of this plant, a rapid, sensitive and reproducible method was established using ultra-high-performance liquid chromatography coupled with a triple quadrupole electrospray tandem mass spectrometry. A total of sixteen flavonoids including five different types (isoflavones, pterocarpans, flavones, flavonols and prenylflavonoids) were simultaneously determined in 10 min. The established method was fully validated in terms of linearity, sensitivity, precision, repeatability as well as recovery and successfully applied in the methanolic extracts of S. flavescens parts (root, stem, leaf, pod and seed). The analysis results indicated that the distribution and contents of different type of flavonoids showed remarkable differences among the five organs of S. flavescens. This study might be useful for the rational utilization of S. flavescens resource. Copyright © 2018 Elsevier B.V. All rights reserved.

  19. VB12-coated Gel-Core-SLN containing insulin: Another way to improve oral absorption.

    PubMed

    He, Haibing; Wang, Puxiu; Cai, Cuifang; Yang, Rui; Tang, Xing

    2015-09-30

    To improve the oral absorption of insulin, a novel carrier of Vitamin B12 (VB12) gel core solid lipid nanopaticles (Gel-Core-SLN, GCSLN) was designed with a gel core, lipid matrix and VB12-coated surface. VB12-stearate was synthesized and characterized by infrared spectroscopy (IR), nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS). Sol-gel conversion following ultrasonic heating and double emulsion technology were combined to implant the insulin-containing gel into solid lipid nanoparticles (SLN). The influence of the mode of administration, food, the amount of VB12-stearate and the particle size on the oral absorption of insulin incorporated in the VB12-GCSLN was investigated. The determined partition coefficient (LogP) of VB12-stearate in a dichloromethane (DCM)-water system was 3.4. This new structure of VB12-GCSLN had higher insulin encapsulation efficiency (EE) of 55.9%, a lower burst release of less than 10% in the first 2h. In vivo studies demonstrated that stronger absorption of insulin with a relative pharmacological availability (PA) of 9.31% compared with the normal insulin-loaded SLN and GCSLN and fairly stable blood glucose levels up to 12h were maintained without any sharp fluctuations. This study suggests that VB12-GCSLN containing insulin appears to be a promising nano carrier for oral delivery of biomacromolecules with relatively high pharmacological availability. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Microwave absorption in powders of small conducting particles for heating applications.

    PubMed

    Porch, Adrian; Slocombe, Daniel; Edwards, Peter P

    2013-02-28

    In microwave chemistry there is a common misconception that small, highly conducting particles heat profusely when placed in a large microwave electric field. However, this is not the case; with the simple physical explanation that the electric field (which drives the heating) within a highly conducting particle is highly screened. Instead, it is the magnetic absorption associated with induction that accounts for the large experimental heating rates observed for small metal particles. We present simple principles for the effective heating of particles in microwave fields from calculations of electric and magnetic dipole absorptions for a range of practical values of particle size and conductivity. For highly conducting particles, magnetic absorption dominates electric absorption over a wide range of particle radii, with an optimum absorption set by the ratio of mean particle radius a to the skin depth δ (specifically, by the condition a = 2.41δ). This means that for particles of any conductivity, optimized magnetic absorption (and hence microwave heating by magnetic induction) can be achieved by simple selection of the mean particle size. For weakly conducting samples, electric dipole absorption dominates, and is maximized when the conductivity is approximately σ ≈ 3ωε(0) ≈ 0.4 S m(-1), independent of particle radius. Therefore, although electric dipole heating can be as effective as magnetic dipole heating for a powder sample of the same volume, it is harder to obtain optimized conditions at a fixed frequency of microwave field. The absorption of sub-micron particles is ineffective in both magnetic and electric fields. However, if the particles are magnetic, with a lossy part to their complex permeability, then magnetic dipole losses are dramatically enhanced compared to their values for non-magnetic particles. An interesting application of this is the use of very small magnetic particles for the selective microwave heating of biological samples.

  1. Interference-free determination of trace copper in freshly ripened honeys by flame atomic absorption spectrometry following a preconcentration by solid-phase extraction and a two-step elution process.

    PubMed

    Pohl, Pawel; Stecka, Helena; Jamroz, Piotr

    2014-02-01

    A fast and straightforward procedure aimed at separating copper (Cu) ions from monosacharides and preconcentrating their traces before flame atomic absorption spectrometry (FAAS) measurements was developed, and its suitability was evaluated by the analysis of freshly ripened honeys on the content of this environmentally and physiologically relevant element. This procedure included the passage (at 20 mL/min) of 10 % (m/v) solutions of honeys (100 mL) through resin beds of Dowex 50 W × 8-400 to retain Cu by solid-phase extraction (SPE) and separate it from the glucose and fructose matrix. In turn, SPE columns were rinsed at 20 mL/min with 20 mL of water and subsequently washed with 20 mL of a 0.5 mol/L HNO3 solution (at 2.0 mL/min) to elute potassium and sodium. Preconcentrated Cu was stripped (at 2.0 mL/min) with 5.0 mL of a 2.0 mol/L HCl solution and determined by FAAS. The proposed procedure was used for the analysis of six ripened monoflower and multiflower honeys, enabling the measurement of Cu within the range of 0.17-0.42 μg/g and with a precision of 3-10%. Recoveries of Cu added to respective honey solutions were within 94-102%, proving the good accuracy of this procedure. The detection limit of Cu achieved with this SPE preconcentration/separation procedure and FAAS detection was 3.6 ng/g.

  2. Optical Absorption in Liquid Semiconductors

    NASA Astrophysics Data System (ADS)

    Bell, Florian Gene

    An infrared absorption cell has been developed which is suitable for high temperature liquids which have absorptions in the range .1-10('3) cm('-1). The cell is constructed by clamping a gasket between two flat optical windows. This unique design allows the use of any optical windows chemically compatible with the liquid. The long -wavelength limit of the measurements is therefore limited only by the choice of the optical windows. The thickness of the cell can easily be set during assembly, and can be varied from 50 (mu)m to .5 cm. Measurements of the optical absorption edge were performed on the liquid alloy Se(,1-x)Tl(,x) for x = 0, .001, .002, .003, .005, .007, and .009, from the melting point up to 475(DEGREES)C. The absorption was found to be exponential in the photon energy over the experimental range from 0.3 eV to 1.2 eV. The absorption increased linearly with concentration according to the empirical relation (alpha)(,T)(h(nu)) = (alpha)(,1) + (alpha)(,2)x, and the absorption (alpha)(,1) was interpreted as the absorption in the absence of T1. (alpha)(,1) also agreed with the measured absorption in 100% Se at corresponding temperatures and energies. The excess absorption defined by (DELTA)(alpha) = (alpha)(,T)(h(nu))-(alpha)(,1) was interpreted as the absorption associated with Tl and was found to be thermally activated with an activation energy E(,t) = 0.5 eV. The exponential edge is explained as absorption on atoms immersed in strong electric fields surrounding ions. The strong fields give rise to an absorption tail similar to the Franz-Keldysh effect. A simple calculation is performed which is based on the Dow-Redfield theory of absorption in an electric field with excitonic effects included. The excess absorption at low photon energies is proportional to the square of the concentration of ions, which are proposed to exist in the liquid according to the relation C(,i) (PROPORTIONAL) x(' 1/2)(.)e('-E)t('/kT), which is the origin of the thermal activation

  3. Band gap of corundumlike α -Ga2O3 determined by absorption and ellipsometry

    NASA Astrophysics Data System (ADS)

    Segura, A.; Artús, L.; Cuscó, R.; Goldhahn, R.; Feneberg, M.

    2017-07-01

    The electronic structure near the band gap of the corundumlike α phase of Ga2O3 has been investigated by means of optical absorption and spectroscopic ellipsometry measurements in the ultraviolet (UV) range (400-190 nm). The absorption coefficient in the UV region and the imaginary part of the dielectric function exhibit two prominent absorption thresholds with wide but well-defined structures at 5.6 and 6.3 eV which have been ascribed to allowed direct transitions from crystal-field split valence bands to the conduction band. Excitonic effects with large Gaussian broadening are taken into account through the Elliott-Toyozawa model, which yields an exciton binding energy of 110 meV and direct band gaps of 5.61 and 6.44 eV. The large broadening of the absorption onset is related to the slightly indirect character of the material.

  4. Mass spectrometry and tandem mass spectrometry of citrus limonoids.

    PubMed

    Tian, Qingguo; Schwartz, Steven J

    2003-10-15

    Methods for atmospheric pressure chemical ionization tandem mass spectrometry (APCI-MS/MS) of citrus limonoid aglycones and electrospray ionization tandem mass spectrometry (ESI-MS/MS) of limonoid glucosides are reported. The fragmentation patterns of four citrus limonoid aglycones (limonin, nomilin, obacunone, and deacetylnomilin) and six limonoid glucosides, that is, limonin 17-beta-D-glucopyranoside (LG), nomilin 17-beta-D-glucopyranoside (NG), nomilinic acid 17-beta-D-glucopyranoside (NAG), deacetyl nomilinic acid 17-beta-D-glucopyranoside (DNAG), obacunone 17-beta-D-glucopyranoside (OG), and obacunoic acid 17-beta-D-glucopyranoside (OAG) were investigated using a quadruple mass spectrometer in low-energy collisionally activated dissociation (CAD). The four limonoid aglycones and four limonoid glucosides (LG, OG, NAG, and DNAG) were purified from citrus seeds; the other two limonoid glucosides (NG and OAG) were tentatively identified in the crude extract of grapefruit seeds by ESI mass spectrometry in both positive and negative ion analysis. Ammonium hydroxide or acetic acid was added to the mobile phase to facilitate ionization. During positive ion APCI analysis of limonoid aglycones, protonated molecular ion, [M + H]+, or adduct ion, [M + NH3 + H]-, was formed as base peaks when ammonium hydroxide was added to the mobile phase. Molecular anions or adduct ions with acetic acid ([M + HOAc - H] and [M + HOAc]-) or a deprotonated molecular ion were produced during negative ion APCI analysis of limonoid aglycones, depending on the mobile-phase modifier used. Positive ion ESI-MS of limonoid glucosides produced adduct ions of [M + H + NH3]+, [M + Na]+, and [M + K]+ when ammonium hydroxide was added to the mobile phase. After collisionally activated dissociation (CAD) of the limonoid aglycone molecular ions in negative ion APCI analysis, fragment ions indicated structural information of the precursor ions, showing the presence of methyl, carboxyl, and oxygenated ring

  5. Advances in explosives analysis—part II: photon and neutron methods

    DOE PAGES

    Brown, Kathryn E.; Greenfield, Margo T.; McGrane, Shawn D.; ...

    2015-10-07

    The number and capability of explosives detection and analysis methods have increased dramatically since publication of the Analytical and Bioanalytical Chemistry special issue devoted to Explosives Analysis [Moore DS, Goodpaster JV, Anal Bioanal Chem 395:245–246, 2009]. Here we review and critically evaluate the latest (the past five years) important advances in explosives detection, with details of the improvements over previous methods, and suggest possible avenues towards further advances in, e.g., stand-off distance, detection limit, selectivity, and penetration through camouflage or packaging. Our review consists of two parts. Part I discussed methods based on animals, chemicals (including colorimetry, molecularly imprinted polymers,more » electrochemistry, and immunochemistry), ions (both ion-mobility spectrometry and mass spectrometry), and mechanical devices. In Part II, we review methods based on photons, from very energetic photons including X-rays and gamma rays down to the terahertz range, and neutrons.« less

  6. Field ion spectrometry: a new technology for cocaine and heroin detection

    NASA Astrophysics Data System (ADS)

    Carnahan, Byron L.; Day, Stephen; Kouznetsov, Viktor; Tarassov, Alexandre

    1997-02-01

    Field ion spectrometry, also known as transverse field compensation ion mobility spectrometry, is a new technique for trace gas analysis that can be applied to the detection of cocaine and heroin. Its principle is based on filtering ion species according to the functional dependence of their mobilities with electric field strength. Field ion spectrometry eliminates the gating electrodes needed in conventional IMS to pulse ions into the spectrometer; instead, ions are injected in to the spectrometer and reach the detector continuously, resulting in improved sensitivity. The technique enables analyses that are difficult with conventional constant field strength ion mobility spectrometers. We have shown that a filed ion spectrometer can selectively detect the vapors from cocaine and heroin emitted from both their base and hydrochloride forms. The estimated volumetric limits of detection are in the low pptv range, based on testing with standardized drug vapor generation systems. The spectrometer can detect cocaine base in the vapor phase, at concentrations well below its estimated 100 pptv vapor pressure equivalent at 20 degrees C. This paper describes the underlying principles of field ion spectrometry in relation to narcotic drug detection, and recent results obtained for cocaine and heroin. The work has been sponsored in part by the United States Advanced Research Projects Agency under contract DAAB10-95C-0004, for the DOD Counterdrug Technology Development Program.

  7. Lead determination at ng/mL level by flame atomic absorption spectrometry using a tantalum coated slotted quartz tube atom trap.

    PubMed

    Demirtaş, İlknur; Bakırdere, Sezgin; Ataman, O Yavuz

    2015-06-01

    Flame atomic absorption spectrometry (FAAS) still keeps its importance despite the relatively low sensitivity; because it is a simple and economical technique for determination of metals. In recent years, atom traps have been developed to increase the sensitivity of FAAS. Although the detection limit of FAAS is only at the level of µg/mL, with the use of atom traps it can reach to ng/mL. Slotted quartz tube (SQT) is one of the atom traps used to improve sensitivity. In atom trapping mode of SQT, analyte is trapped on-line in SQT for few minutes using ordinary sample aspiration, followed by the introduction of a small volume of organic solvent to effect the revolatilization and atomization of analyte species resulting in a transient signal. This system is economical, commercially available and easy to use. In this study, a sensitive analytical method was developed for the determination of lead with the help of SQT atom trapping flame atomization (SQT-AT-FAAS). 574 Fold sensitivity enhancement was obtained at a sample suction rate of 3.9 mL/min for 5.0 min trapping period with respect to FAAS. Organic solvent was selected as 40 µL of methyl isobutyl ketone (MIBK). To obtain a further sensitivity enhancement inner surface of SQT was coated with several transition metals. The best sensitivity enhancement, 1650 fold enhancement, was obtained by the Ta-coated SQT-AT-FAAS. In addition, chemical nature of Pb species trapped on quartz and Ta surface, and the chemical nature of Ta on quartz surface were investigated by X-ray photoelectron spectroscopy (XPS) and Raman Spectroscopy. Raman spectrometric results indicate that tantalum is coated on SQT surface in the form of Ta2O5. XPS studies revealed that the oxidation state of Pb in species trapped on both bare and Ta coated SQT surfaces is +2. For the accuracy check, the analyses of standard reference material were performed by use of SCP SCIENCE EnviroMAT Low (EU-L-2) and results for Pb were to be in good agreement with

  8. Rutherford Backscattering Spectrometry studies of 100 keV nitrogen ion implanted polypropylene polymer

    NASA Astrophysics Data System (ADS)

    Chawla, Mahak; Aggarwal, Sanjeev; Sharma, Annu

    2017-09-01

    The effect of nitrogen ion implantation on the structure and composition in polypropylene (PP) polymer has been studied. Implantation was carried out using 100 keV N+ ions at different fluences of 1 × 1015, 1 × 1016 and 1 × 1017 ions cm-2 with beam current density of ∼0.65 μA cm-2. Surface morphological changes in the pre- and post-implanted PP specimens have been studied using Rutherford Backscattering Spectrometry (RBS) and UV-Visible Spectroscopy. The spatial distribution of implantation induced modification in the form of carbonization and dehydrogenation in the near surface region of PP matrix, the projected range, retained dose of implanted nitrogen, the various elements present in the implanted layers and their differential cross-sections have been analyzed using RBS spectra. RUMP simulation yielded an increase in the concentration of carbon near the surface from 33 at.% (virgin) to 42 at.% at fluence of 1 × 1017 N+ cm-2. Further, optical absorption has been found to increase with a shift in the absorption edge from UV towards visible region with increasing fluence. UV-Vis absorption spectra also indicate a drastic decrease in optical energy gap from 4.12 eV (virgin) to 0.25 eV (1 × 1017 N+ cm-2) indicating towards the formation of carbonaceous network in the implanted region. All these changes observed using UV-Visible have been further correlated with the outcomes of the RBS characterization.

  9. Detection of radioactive particles offshore by γ-ray spectrometry Part I: Monte Carlo assessment of detection depth limits

    NASA Astrophysics Data System (ADS)

    Maučec, M.; de Meijer, R. J.; Rigollet, C.; Hendriks, P. H. G. M.; Jones, D. G.

    2004-06-01

    A joint research project between the British Geological Survey and Nuclear Geophysics Division of the Kernfysisch Versneller Instituut, Groningen, the Netherlands, was commissioned by the United Kingdom Atomic Energy Authority to establish the efficiency of a towed seabed γ-ray spectrometer for the detection of 137Cs-containing radioactive particles offshore Dounreay, Scotland. Using the MCNP code, a comprehensive Monte Carlo feasibility study was carried out to model various combinations of geological matrices, particle burial depth and lateral displacement, source activity and detector material. To validate the sampling and absolute normalisation procedures of MCNP for geometries including multiple (natural and induced) heterogeneous sources in environmental monitoring, a benchmark experiment was conducted. The study demonstrates the ability of seabed γ-ray spectrometry to locate radioactive particles offshore and to distinguish between γ count rate increases due to particles from those due to enhanced natural radioactivity. The information presented in this study will be beneficial for estimation of the inventory of 137Cs particles and their activity distribution and for the recovery of particles from the sea floor. In this paper, the Monte Carlo assessment of the detection limits is presented. The estimation of the required towing speed and acquisition times and their application to radioactive particle detection and discrimination offshore formed a supplementary part of this study.

  10. Influence of multiple scattering and absorption on the full scattering profile and the isobaric point in tissue

    NASA Astrophysics Data System (ADS)

    Duadi, Hamootal; Fixler, Dror

    2015-05-01

    Light reflectance and transmission from soft tissue has been utilized in noninvasive clinical measurement devices such as the photoplethysmograph (PPG) and reflectance pulse oximeter. Incident light on the skin travels into the underlying layers and is in part reflected back to the surface, in part transferred and in part absorbed. Most methods of near infrared (NIR) spectroscopy focus on the volume reflectance from a semi-infinite sample, while very few measure transmission. We have previously shown that examining the full scattering profile (angular distribution of exiting photons) provides more comprehensive information when measuring from a cylindrical tissue. Furthermore, an isobaric point was found which is not dependent on changes in the reduced scattering coefficient. The angle corresponding to this isobaric point depends on the tissue diameter. We investigated the role of multiple scattering and absorption on the full scattering profile of a cylindrical tissue. First, we define the range in which multiple scattering occurs for different tissue diameters. Next, we examine the role of the absorption coefficient in the attenuation of the full scattering profile. We demonstrate that the absorption linearly influences the intensity at each angle of the full scattering profile and, more importantly, the absorption does not change the position of the isobaric point. The findings of this work demonstrate a realistic model for optical tissue measurements such as NIR spectroscopy, PPG, and pulse oximetery.

  11. Iron-59 absorption from soy hulls: intrinsic vs extrinsic labeling

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lykken, G.I.; Mahalko, J.R.; Nielsen, E.J.

    As part of an evaluation of the validity of the extrinsic labeling technique for measuring iron absorption, absorption from soy hulls extrinsically labeled (/sup 59/Fe added to bread dough) was compared with that from soy hulls intrinsically labeled (/sup 59/Fe incorporated into the soy plant during growth). Century soybeans were grown in a greenhouse. After pods had formed and were filling, each plant was stem injected twice, at 3 day intervals, with 22 ..mu..Ci /sup 59/Fe as FeCl/sub 2/ in 25 ..mu..l of 0.5 M HCl solution. After the plants had senesced, the soybeans were harvested, dried, shelled and themore » hulls removed. Standard meals containing 3.5 mg Fe/meal and up to 0.06 ..mu..Ci /sup 59/Fe in a soy hull bun were fed on 2 consecutive days to free-living volunteers in a crossover design. Absorption of /sup 59/Fe was greater from intrinsically labeled soy hulls than from extrinsically labeled soy hulls, 20 +/- 20% vs 15 +/- 11% (n=14, p > 0.05 by paired t-test). Apparent absorption ranged from 1.3% to 77% from intrinsically labeled soy hulls and .5% to 29% from extrinsically labeled soy hulls with the highest absorption occurring in persons with low serum ferritin (S.F. < 8 ng/ml). These findings provide additional evidence that the extrinsic labeling method is a valid measure of iron bioavailability to humans.« less

  12. Methylmercury determination in seafood by photochemical vapor generation capacitively coupled plasma microtorch optical emission spectrometry.

    PubMed

    Covaci, Eniko; Senila, Marin; Ponta, Michaela; Darvasi, Eugen; Petreus, Dorin; Frentiu, Maria; Frentiu, Tiberiu

    2017-08-01

    A non-chromatographic method based on double liquid-liquid extraction and measurements by UV photochemical vapor generation capacitively coupled plasma microtorch optical emission spectrometry was developed and characterized for methylmercury determination in seafood. Samples were prepared following the procedure recommended in JRC Technical Report of European Commission formerly proposed for the determination of methylmercury in seafood by thermal decomposition atomic absorption spectrometry, namely confinement of Hg species in 47% HBr solution, extraction of CH 3 Hg + in toluene and back-extraction in 1% l-cysteine aqueous solution. Mercury cold vapor was generated by flow injection UV photo-reduction from CH 3 Hg + in 0.6molL -1 HCOOH, while quantification was performed against external Hg 2+ aqueous standards and measuring Hg 253.652nm emission using a low power/Ar consumption plasma microtorch (15W, 100mLmin -1 ) and a low resolution microspectrometer (Ocean Optics). The figures of merit and analytical capability were assessed by analyzing certified reference materials and test samples of fish fillet and discussed in relation with requirements for Hg determination in seafood in European legislation (Decisions 2007/333/EC and 2002/657/EC) as well as compared to performances achieved in thermal decomposition atomic absorption spectrometry. The limit of detection and quantification of 2µgkg -1 and 6µgkg -1 respectively, precision of 2.7-9.4% and accuracy of 99±8% of the proposed method for the determination of CH 3 Hg + fulfill the demands of European legislation for Hg quantification. The limit of detection and quantification were better than those in the used reference method or other non-/chromatographic methods taken for comparison. The analysis of certified reference materials and the Bland and Altman test performed on 12 test samples confirmed trueness of the proposed method and its reliability for the determination of traces of CH 3 Hg + with 95

  13. Arsenic Speciation of Waters from the Aegean Region, Turkey by Hydride Generation: Atomic Absorption Spectrometry.

    PubMed

    Çiftçi, Tülin Deniz; Henden, Emur

    2016-08-01

    Arsenic in drinking water is a serious problem for human health. Since the toxicity of arsenic species As(III) and As(V) is different, it is important to determine the concentrations separately. Therefore, it is necessary to develop an accurate and sensitive method for the speciation of arsenic. It was intended with this work to determine the concentrations of arsenic species in water samples collected from Izmir, Manisa and nearby areas. A batch type hydride generation atomic absorption spectrometer was used. As(V) gave no signal under the optimal measurement conditions of As(III). A certified reference drinking water was analyzed by the method and the results showed excellent agreement with the reported values. The procedure was applied to 34 water samples. Eleven tap water, two spring water, 19 artesian well water and two thermal water samples were analyzed under the optimal conditions.

  14. Prediction of sound absorption in rigid porous media with the lattice Boltzmann method

    NASA Astrophysics Data System (ADS)

    da Silva, Andrey Ricardo; Mareze, Paulo; Brandão, Eric

    2016-02-01

    In this work, sound absorption phenomena associated with the viscous shear stress within rigid porous media is investigated with a simple isothermal lattice Boltzmann BGK model. Simulations are conducted for different macroscopic material properties such as sample thickness and porosity and the results are compared with the exact analytical solution for materials with slit-like structure in terms of acoustic impedance and sound absorption coefficient. The numerical results agree very well with the exact solution, particularly for the sound absorption coefficient. The small deviations found in the low frequency limit for the real part of the acoustic impedance are attributed to the ratio between the thicknesses of the slit and the viscous boundary layer. The results suggest that the lattice Boltzmann method can be a very compelling numerical tool for simulating viscous sound absorption phenomena in the time domain, particularly due to its computational simplicity when compared to traditional continuum based techniques.

  15. Identification of Unknown Contaminants in Water Samples from ISS Employing Liquid Chromatography/Mass Spectrometry/Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Rutz, Jeffrey A.; Schultz, John R.

    2008-01-01

    Mass Spectrometry/Mass Spectrometry (MS/MS) is a powerful technique for identifying unknown organic compounds. For non-volatile or thermally unstable unknowns dissolved in liquids, liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS) is often the variety of MS/MS used for the identification. One type of LC/MS/MS that is rapidly becoming popular is time-of-flight (TOF) mass spectrometry. This technique is now in use at the Johnson Space Center for identification of unknown nonvolatile organics in water samples from the space program. An example of the successful identification of one unknown is reviewed in detail in this paper. The advantages of time-of-flight instrumentation are demonstrated through this example as well as the strategy employed in using time-of-flight data to identify unknowns.

  16. Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations for solvent-based carbon capture. Part 2: Chemical absorption across a wetted wall column: Original Research Article: Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations

    DOE PAGES

    Wang, Chao; Xu, Zhijie; Lai, Kevin; ...

    2017-10-24

    Part 1 of this paper presents a numerical model for non-reactive physical mass transfer across a wetted wall column (WWC). In Part 2, we improved the existing computational fluid dynamics (CFD) model to simulate chemical absorption occurring in a WWC as a bench-scale study of solvent-based carbon dioxide (CO 2) capture. In this study, to generate data for WWC model validation, CO 2 mass transfer across a monoethanolamine (MEA) solvent was first measured on a WWC experimental apparatus. The numerical model developed in this work can account for both chemical absorption and desorption of CO 2 in MEA. In addition,more » the overall mass transfer coefficient predicted using traditional/empirical correlations is conducted and compared with CFD prediction results for both steady and wavy falling films. A Bayesian statistical calibration algorithm is adopted to calibrate the reaction rate constants in chemical absorption/desorption of CO 2 across a falling film of MEA. The posterior distributions of the two transport properties, i.e., Henry's constant and gas diffusivity in the non-reacting nitrous oxide (N 2O)/MEA system obtained from Part 1 of this study, serves as priors for the calibration of CO 2 reaction rate constants after using the N 2O/CO 2 analogy method. Finally, the calibrated model can be used to predict the CO 2 mass transfer in a WWC for a wider range of operating conditions.« less

  17. Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations for solvent-based carbon capture. Part 2: Chemical absorption across a wetted wall column: Original Research Article: Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Chao; Xu, Zhijie; Lai, Kevin

    Part 1 of this paper presents a numerical model for non-reactive physical mass transfer across a wetted wall column (WWC). In Part 2, we improved the existing computational fluid dynamics (CFD) model to simulate chemical absorption occurring in a WWC as a bench-scale study of solvent-based carbon dioxide (CO 2) capture. In this study, to generate data for WWC model validation, CO 2 mass transfer across a monoethanolamine (MEA) solvent was first measured on a WWC experimental apparatus. The numerical model developed in this work can account for both chemical absorption and desorption of CO 2 in MEA. In addition,more » the overall mass transfer coefficient predicted using traditional/empirical correlations is conducted and compared with CFD prediction results for both steady and wavy falling films. A Bayesian statistical calibration algorithm is adopted to calibrate the reaction rate constants in chemical absorption/desorption of CO 2 across a falling film of MEA. The posterior distributions of the two transport properties, i.e., Henry's constant and gas diffusivity in the non-reacting nitrous oxide (N 2O)/MEA system obtained from Part 1 of this study, serves as priors for the calibration of CO 2 reaction rate constants after using the N 2O/CO 2 analogy method. Finally, the calibrated model can be used to predict the CO 2 mass transfer in a WWC for a wider range of operating conditions.« less

  18. Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations for solvent-based carbon capture. Part 2: Chemical absorption across a wetted wall column: Original Research Article: Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Chao; Xu, Zhijie; Lai, Kevin

    Part 1 of this paper presents a numerical model for non-reactive physical mass transfer across a wetted wall column (WWC). In Part 2, we improved the existing computational fluid dynamics (CFD) model to simulate chemical absorption occurring in a WWC as a bench-scale study of solvent-based carbon dioxide (CO2) capture. To generate data for WWC model validation, CO2 mass transfer across a monoethanolamine (MEA) solvent was first measured on a WWC experimental apparatus. The numerical model developed in this work can account for both chemical absorption and desorption of CO2 in MEA. In addition, the overall mass transfer coefficient predictedmore » using traditional/empirical correlations is conducted and compared with CFD prediction results for both steady and wavy falling films. A Bayesian statistical calibration algorithm is adopted to calibrate the reaction rate constants in chemical absorption/desorption of CO2 across a falling film of MEA. The posterior distributions of the two transport properties, i.e., Henry's constant and gas diffusivity in the non-reacting nitrous oxide (N2O)/MEA system obtained from Part 1 of this study, serves as priors for the calibration of CO2 reaction rate constants after using the N2O/CO2 analogy method. The calibrated model can be used to predict the CO2 mass transfer in a WWC for a wider range of operating conditions.« less

  19. Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations for solvent-based carbon capture. Part 2: Chemical absorption across a wetted wall column: Original Research Article: Hierarchical calibration and validation framework of bench-scale computational fluid dynamics simulations

    DOE PAGES

    Wang, Chao; Xu, Zhijie; Lai, Kevin; ...

    2017-10-24

    Part 1 of this paper presents a numerical model for non-reactive physical mass transfer across a wetted wall column (WWC). In Part 2, we improved the existing computational fluid dynamics (CFD) model to simulate chemical absorption occurring in a WWC as a bench-scale study of solvent-based carbon dioxide (CO2) capture. To generate data for WWC model validation, CO2 mass transfer across a monoethanolamine (MEA) solvent was first measured on a WWC experimental apparatus. The numerical model developed in this work can account for both chemical absorption and desorption of CO2 in MEA. In addition, the overall mass transfer coefficient predictedmore » using traditional/empirical correlations is conducted and compared with CFD prediction results for both steady and wavy falling films. A Bayesian statistical calibration algorithm is adopted to calibrate the reaction rate constants in chemical absorption/desorption of CO2 across a falling film of MEA. The posterior distributions of the two transport properties, i.e., Henry's constant and gas diffusivity in the non-reacting nitrous oxide (N2O)/MEA system obtained from Part 1 of this study, serves as priors for the calibration of CO2 reaction rate constants after using the N2O/CO2 analogy method. The calibrated model can be used to predict the CO2 mass transfer in a WWC for a wider range of operating conditions.« less

  20. Plasma sterol evidence for decreased absorption and increased synthesis of cholesterol in insulin resistance and obesity.

    PubMed

    Paramsothy, Pathmaja; Knopp, Robert H; Kahn, Steven E; Retzlaff, Barbara M; Fish, Brian; Ma, Lina; Ostlund, Richard E

    2011-11-01

    The rise in LDL with egg feeding in lean insulin-sensitive (LIS) participants is 2- and 3-fold greater than in lean insulin-resistant (LIR) and obese insulin-resistant (OIR) participants, respectively. We determined whether differences in cholesterol absorption, synthesis, or both could be responsible for these differences by measuring plasma sterols as indexes of cholesterol absorption and endogenous synthesis. Plasma sterols were measured by gas chromatography-mass spectrometry in a random subset of 34 LIS, 37 LIR, and 37 OIR participants defined by the insulin sensitivity index (S(I)) and by BMI criteria selected from a parent group of 197 participants. Cholestanol and plant sterols provide a measure of cholesterol absorption, and lathosterol provides a measure of cholesterol synthesis. The mean (±SD) ratio of plasma total absorption biomarker sterols to cholesterol was 4.48 ± 1.74 in LIS, 3.25 ± 1.06 in LIR, and 2.82 ± 1.08 in OIR participants. After adjustment for age and sex, the relations of the absorption sterol-cholesterol ratios were as follows: LIS > OIR (P < 0.001), LIS > LIR (P < 0.001), and LIR > OIR (P = 0.11). Lathosterol-cholesterol ratios were 0.71 ± 0.32 in the LIS participants, 0.95 ± 0.47 in the LIR participants, and 1.29 ± 0.55 in the OIR participants. After adjustment for age and sex, the relations of lathosterol-cholesterol ratios were as follows: LIS < OIR (P < 0.001), LIS < LIR (P = 0.03), and LIR < OIR (P = 0.002). Total sterol concentrations were positively associated with S(I) and negatively associated with obesity, whereas lathosterol correlations were the opposite. Cholesterol absorption was highest in the LIS participants, whereas cholesterol synthesis was highest in the LIR and OIR participants. Therapeutic diets for hyperlipidemia should emphasize low-cholesterol diets in LIS persons and weight loss to improve S(I) and to decrease cholesterol overproduction in LIR and OIR persons.

  1. Temporal intracavity detection of parasitic infrared absorption in Ti:Sapphire lasers

    NASA Astrophysics Data System (ADS)

    Deleva, A. D.; Peshev, Z. Y.; Aneva, Z. I.

    1993-12-01

    An intracavity technique with temporal sensitivity to optical losses is used to detect parasitic infrared absorption (PIRA) in Ti:sapphire crystals with high active-center concentrations. By means of comparative analysis, re-emission is established of part of the parasitically absorbed energy back into the laser action channel. A method is proposed for approximate quantitative determination of the relative part of re-emitting PIRA-centers with respect to their total number; for the highly-doped crystal described, it is estimated at about 11%.

  2. A new supramolecular based liquid solid microextraction method for preconcentration and determination of trace bismuth in human blood serum and hair samples by electrothermal atomic absorption spectrometry.

    PubMed

    Kahe, Hadi; Chamsaz, Mahmoud

    2016-11-01

    A simple and reliable supramolecule-aggregated liquid solid microextraction method is described for preconcentration and determination of trace amounts of bismuth in water as well as human blood serum and hair samples. Catanionic microstructures of cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) surfactants, dissolved in deionized water/propanol, are used as a green solvent to extract bismuth (III)-diethyldithiocarbamate complexes by dispersive microextraction methodology. The extracted solid phase is easily removed and dissolved in 50 μL propanol for subsequent measurement by electrothermal atomic absorption spectrometry (ET-AAS). The procedure benefits the merits of supramolecule aggregates' properties and dispersive microextraction technique using water as the main component of disperser solvent, leading to direct interaction with analyte. Phase separation behavior of extraction solvent and different parameters influencing the extraction efficiency of bismuth ion such as salt concentration, pH, centrifugation time, amount of chelating agent, SDS:CTAB mole ratio, and solvent amounts were thoroughly optimized. Under the optimal experimental conditions, the calibration curve was linear in the range of 0.3-6 μg L -1 Bi (III) with a limit of detection (LOD) of 0.16 μg L -1 (S/N = 3). The relative standard deviations (RSD) of determination were obtained to be 5.1 and 6.2 % for 1 and 3 μg L -1 of Bi (III), respectively. The developed method was successfully applied as a sensitive and accurate technique for determination of bismuth ion in human blood serum, hair samples, and a certified reference material.

  3. High-Resolution Fast-Neutron Spectrometry for Arms Control and Treaty Verification

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    David L. Chichester; James T. Johnson; Edward H. Seabury

    2012-07-01

    Many nondestructive nuclear analysis techniques have been developed to support the measurement needs of arms control and treaty verification, including gross photon and neutron counting, low- and high-resolution gamma spectrometry, time-correlated neutron measurements, and photon and neutron imaging. One notable measurement technique that has not been extensively studied to date for these applications is high-resolution fast-neutron spectrometry (HRFNS). Applied for arms control and treaty verification, HRFNS has the potential to serve as a complimentary measurement approach to these other techniques by providing a means to either qualitatively or quantitatively determine the composition and thickness of non-nuclear materials surrounding neutron-emitting materials.more » The technique uses the normally-occurring neutrons present in arms control and treaty verification objects of interest as an internal source of neutrons for performing active-interrogation transmission measurements. Most low-Z nuclei of interest for arms control and treaty verification, including 9Be, 12C, 14N, and 16O, possess fast-neutron resonance features in their absorption cross sections in the 0.5- to 5-MeV energy range. Measuring the selective removal of source neutrons over this energy range, assuming for example a fission-spectrum starting distribution, may be used to estimate the stoichiometric composition of intervening materials between the neutron source and detector. At a simpler level, determination of the emitted fast-neutron spectrum may be used for fingerprinting 'known' assemblies for later use in template-matching tests. As with photon spectrometry, automated analysis of fast-neutron spectra may be performed to support decision making and reporting systems protected behind information barriers. This paper will report recent work at Idaho National Laboratory to explore the feasibility of using HRFNS for arms control and treaty verification applications, including simulations

  4. Combustion chemistry and flame structure of furan group biofuels using molecular-beam mass spectrometry and gas chromatography - Part I: Furan.

    PubMed

    Liu, Dong; Togbé, Casimir; Tran, Luc-Sy; Felsmann, Daniel; Oßwald, Patrick; Nau, Patrick; Koppmann, Julia; Lackner, Alexander; Glaude, Pierre-Alexandre; Sirjean, Baptiste; Fournet, René; Battin-Leclerc, Frédérique; Kohse-Höinghaus, Katharina

    2014-03-01

    Fuels of the furan family, i.e. furan itself, 2-methylfuran (MF), and 2,5-dimethylfuran (DMF) are being proposed as alternatives to hydrocarbon fuels and are potentially accessible from cellulosic biomass. While some experiments and modeling results are becoming available for each of these fuels, a comprehensive experimental and modeling analysis of the three fuels under the same conditions, simulated using the same chemical reaction model, has - to the best of our knowledge - not been attempted before. The present series of three papers, detailing the results obtained in flat flames for each of the three fuels separately, reports experimental data and explores their combustion chemistry using kinetic modeling. The first part of this series focuses on the chemistry of low-pressure furan flames. Two laminar premixed low-pressure (20 and 40 mbar) flat argon-diluted (50%) flames of furan were studied at two equivalence ratios (φ=1.0 and 1.7) using an analytical combination of high-resolution electron-ionization molecular-beam mass spectrometry (EI-MBMS) in Bielefeld and gas chromatography (GC) in Nancy. The time-of-flight MBMS with its high mass resolution enables the detection of both stable and reactive species, while the gas chromatograph permits the separation of isomers. Mole fractions of reactants, products, and stable and radical intermediates were measured as a function of the distance to the burner. A single kinetic model was used to predict the flame structure of the three fuels: furan (in this paper), 2-methylfuran (in Part II), and 2,5-dimethylfuran (in Part III). A refined sub-mechanism for furan combustion, based on the work of Tian et al. [Combustion and Flame 158 (2011) 756-773] was developed which was then compared to the present experimental results. Overall, the agreement is encouraging. The main reaction pathways involved in furan combustion were delineated computing the rates of formation and consumption of all species. It is seen that the

  5. ANALYSIS OF ANIONIC METALLIZED AZO AND FORMAZAN DYES BY CAPILLARY ELECTROPHORESIS/MASS SPECTROMETRY

    EPA Science Inventory

    Capillary electrophoresis-mass spectrometry was applied to the separation of several anionic dyes containing copper(II), chromium(III), or cobalt(III) as part of the dye molecule. The dyes were separated using a 110 cmX50 mu m uncoated fused-silica capillary and a 5 mM ammonium a...

  6. Electromagnetic absorption properties of spacecraft and space debris

    NASA Astrophysics Data System (ADS)

    Micheli, D.; Santoni, F.; Giusti, A.; Delfini, A.; Pastore, R.; Vricella, A.; Albano, M.; Arena, L.; Piergentili, F.; Marchetti, M.

    2017-04-01

    Aim of the work is to present a method to evaluate the electromagnetic absorption properties of spacecraft and space debris. For these objects, the radar detection ability depends mainly on volume, shape, materials type and other electromagnetic reflecting behaviour of spacecraft surface components, such as antennas or thermal blankets, and of metallic components in space debris. The higher the electromagnetic reflection coefficient of such parts, the greater the radar detection possibility. In this research an electromagnetic reverberation chamber is used to measure the absorption cross section (ACS) of four objects which may represent space structure operating components as well as examples of space debris: a small satellite, a composite antenna dish, a Thermal Protection System (TPS) tile and a carbon-based composite missile shell. The ACS mainly depends on geometrical characteristics like apertures, face numbers and bulk porosity, as well as on the type of the material itself. The ACS, which is an electromagnetic measurement, is expressed in squared meters and thus can be compared with the objects geometrical cross section. A small ACS means a quite electromagnetic reflective tendency, which is beneficial for radar observations; on the contrary, high values of ACS indicate a strong absorption of the electromagnetic field, which in turn can result a critical hindering of radar tracking.

  7. Cobalt internal standard for Ni to assist the simultaneous determination of Mo and Ni in plant materials by high-resolution continuum source graphite furnace atomic absorption spectrometry employing direct solid sample analysis.

    PubMed

    de Babos, Diego Victor; Bechlin, Marcos André; Barros, Ariane Isis; Ferreira, Edilene Cristina; Gomes Neto, José Anchieta; de Oliveira, Silvana Ruella

    2016-05-15

    A new method is proposed for the simultaneous determination of Mo and Ni in plant materials by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS), employing direct solid sample analysis (DSS) and internal standardization (IS). Cobalt was used as internal standard to minimize matrix effects during Ni determinations, enabling the use of aqueous standards for calibration. Correlation coefficients for the calibration curves were typically better than 0.9937. The performance of the method was checked by analysis of six plant certified reference materials, and the results for Mo and Ni were in agreement with the certified values (95% confidence level, t-test). Analysis was made of different types of plant materials used as renewable sources of energy, including sugarcane leaves, banana tree fiber, soybean straw, coffee pods, orange bagasse, peanut hulls, and sugarcane bagasse. The concentrations found for Mo and Ni ranged from 0.08 to 0.63 ng mg(-1) and from 0.41 to 6.92 ng mg(-1), respectively. Precision (RSD) varied from 2.1% to 11% for Mo and from 3.7% to 10% for Ni. Limits of quantification of 0.055 and 0.074 ng were obtained for Mo and Ni, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Halloysite nanotubes as a solid sorbent in ultrasound-assisted dispersive micro solid-phase extraction for the determination of bismuth in water samples using high-resolution continuum source graphite-furnace atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Krawczyk-Coda, Magdalena

    2017-03-01

    In this research, a simple, accurate, and inexpensive preconcentration procedure was developed for the determination of bismuth in water samples, using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR CS GFAAS). During the preconcentration step, halloysite nanotubes (HNTs) were used as a solid sorbent in ultrasound-assisted dispersive micro solid-phase extraction (USA DMSPE). The influence of the pH of the sample solution, amount of HNTs, and extraction time, as well as of the main parameters of HR CS GFAAS, on absorbance was investigated. The limit of detection was 0.005 μg L- 1. The preconcentration factor achieved for bismuth was 32. The relative standard deviation (RSD) was 4%. The accuracy of this method was validated by analyses of NIST SRM 1643e (Trace elements in water) and TMDA-54.5 (A high level fortified sample for trace elements) certified reference materials. The measured bismuth contents in these certified reference materials were in satisfactory agreement with the certified values according to the t-test for a 95% confidence level. The proposed method has been successfully applied to the determination of bismuth in five different real water samples (seawater, lake water, river water, stream water and rain water).

  9. Gastrointestinal citrate absorption in nephrolithiasis

    NASA Technical Reports Server (NTRS)

    Fegan, J.; Khan, R.; Poindexter, J.; Pak, C. Y.

    1992-01-01

    Gastrointestinal absorption of citrate was measured in stone patients with idiopathic hypocitraturia to determine if citrate malabsorption could account for low urinary citrate. Citrate absorption was measured directly from recovery of orally administered potassium citrate (40 mEq.) in the intestinal lavage fluid, using an intestinal washout technique. In 7 stone patients citrate absorption, serum citrate levels, peak citrate concentration in serum and area under the curve were not significantly different from those of 7 normal subjects. Citrate absorption was rapid and efficient in both groups, with 96 to 98% absorbed within 3 hours. The absorption of citrate was less efficient from a tablet preparation of potassium citrate than from a liquid preparation, probably due to a delayed release of citrate from wax matrix. However, citrate absorption from solid potassium citrate was still high at 91%, compared to 98% for a liquid preparation. Thus, hypocitraturia is unlikely to be due to an impaired gastrointestinal absorption of citrate in stone patients without overt bowel disease.

  10. An improved methodology of asymmetric flow field flow fractionation hyphenated with inductively coupled mass spectrometry for the determination of size distribution of gold nanoparticles in dietary supplements.

    PubMed

    Mudalige, Thilak K; Qu, Haiou; Linder, Sean W

    2015-11-13

    Engineered nanoparticles are available in large numbers of commercial products claiming various health benefits. Nanoparticle absorption, distribution, metabolism, excretion, and toxicity in a biological system are dependent on particle size, thus the determination of size and size distribution is essential for full characterization. Number based average size and size distribution is a major parameter for full characterization of the nanoparticle. In the case of polydispersed samples, large numbers of particles are needed to obtain accurate size distribution data. Herein, we report a rapid methodology, demonstrating improved nanoparticle recovery and excellent size resolution, for the characterization of gold nanoparticles in dietary supplements using asymmetric flow field flow fractionation coupled with visible absorption spectrometry and inductively coupled plasma mass spectrometry. A linear relationship between gold nanoparticle size and retention times was observed, and used for characterization of unknown samples. The particle size results from unknown samples were compared to results from traditional size analysis by transmission electron microscopy, and found to have less than a 5% deviation in size for unknown product over the size range from 7 to 30 nm. Published by Elsevier B.V.

  11. Subgap Absorption in Conjugated Polymers

    DOE R&D Accomplishments Database

    Sinclair, M.; Seager, C. H.; McBranch, D.; Heeger, A. J; Baker, G. L.

    1991-01-01

    Along with X{sup (3)}, the magnitude of the optical absorption in the transparent window below the principal absorption edge is an important parameter which will ultimately determine the utility of conjugated polymers in active integrated optical devices. With an absorptance sensitivity of < 10{sup {minus}5}, Photothermal Deflection Spectroscopy (PDS) is ideal for determining the absorption coefficients of thin films of transparent'' materials. We have used PDS to measure the optical absorption spectra of the conjugated polymers poly(1,4-phenylene-vinylene) (and derivitives) and polydiacetylene-4BCMU in the spectral region from 0.55 eV to 3 eV. Our spectra show that the shape of the absorption edge varies considerably from polymer to polymer, with polydiacetylene-4BCMU having the steepest absorption edge. The minimum absorption coefficients measured varied somewhat with sample age and quality, but were typically in the range 1 cm{sup {minus}1} to 10 cm{sup {minus}1}. In the region below 1 eV, overtones of C-H stretching modes were observed, indicating that further improvements in transparency in this spectral region might be achieved via deuteration of fluorination.

  12. Absorption of acoustic waves by sunspots. II - Resonance absorption in axisymmetric fibril models

    NASA Technical Reports Server (NTRS)

    Rosenthal, C. S.

    1992-01-01

    Analytical calculations of acoustic waves scattered by sunspots which concentrate on the absorption at the magnetohydrodynamic Alfven resonance are extended to the case of a flux-tube embedded in a uniform atmosphere. The model is based on a flux-tubes of varying radius that are highly structured, translationally invariant, and axisymmetric. The absorbed fractional energy is determined for different flux-densities and subphotospheric locations with attention given to the effects of twist. When the flux is highly concentrated into annuli efficient absorption is possible even when the mean magnetic flux density is low. The model demonstrates low absorption at low azimuthal orders even in the presence of twist which generally increases the range of wave numbers over which efficient absorption can occur. Resonance absorption is concluded to be an efficient mechanism in monolithic sunspots, fibril sunspots, and plage fields.

  13. Absorption and quasiguided mode analysis of organic solar cells with photonic crystal photoactive layers.

    PubMed

    Tumbleston, John R; Ko, Doo-Hyun; Samulski, Edward T; Lopez, Rene

    2009-04-27

    We analyze optical absorption enhancements and quasiguided mode properties of organic solar cells with highly ordered nanostructured photoactive layers comprised of the bulk heterojunction blend, poly-3-hexylthiophene/[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) and a low index of refraction conducting material (LICM). This photonic crystal geometry is capable of enhancing spectral absorption by approximately 17% in part due to the excitation of quasiguided modes near the band edge of P3HT:PCBM. A nanostructure thickness between 200 nm and 300 nm is determined to be optimal, while the LICM must have an index of refraction approximately 0.3 lower than P3HT:PCBM to produce absorption enhancements. Quasiguided modes that differ in lifetime by an order of magnitude are also identified and yield absorption that is concentrated in the P3HT:PCBM flash layer.

  14. Development of a High-Resolution Laser Absorption Spectroscopy Method with Application to the Determination of Absolute Concentration of Gaseous Elemental Mercury in Air.

    PubMed

    Srivastava, Abneesh; Hodges, Joseph T

    2018-06-05

    Isotope dilution-cold-vapor-inductively coupled plasma mass spectrometry (ID-CV-ICPMS) has become the primary standard for measurement of gaseous elemental mercury (GEM) mass concentration. However, quantitative mass spectrometry is challenging for several reasons including (1) the need for isotopic spiking with a standard reference material, (2) the requirement for bias-free passive sampling protocols, (3) the need for stable mass spectrometry interface design, and (4) the time and cost involved for gas sampling, sample processing, and instrument calibration. Here, we introduce a high-resolution laser absorption spectroscopy method that eliminates the need for sample-specific calibration standards or detailed analysis of sample treatment losses. This technique involves a tunable, single-frequency laser absorption spectrometer that measures isotopically resolved spectra of elemental mercury (Hg) spectra of 6 1 S 0 ← 6 3 P 1 intercombination transition near λ = 253.7 nm. Measured spectra are accurately modeled from first-principles using the Beer-Lambert law and Voigt line profiles combined with literature values for line positions, line shape parameters, and the spontaneous emission Einstein coefficient to obtain GEM mass concentration values. We present application of this method for the measurement of the equilibrium concentration of mercury vapor near room temperature. Three closed systems are considered: two-phase mixtures of liquid Hg and its vapor and binary two-phase mixtures of Hg-air and Hg-N 2 near atmospheric pressure. Within the experimental relative standard uncertainty, 0.9-1.5% congruent values of the equilibrium Hg vapor concentration are obtained for the Hg-only, Hg-air, Hg-N 2 systems, in confirmation with thermodynamic predictions. We also discuss detection limits and the potential of the present technique to serve as an absolute primary standard for measurements of gas-phase mercury concentration and isotopic composition.

  15. Petawatt laser absorption bounded

    PubMed Central

    Levy, Matthew C.; Wilks, Scott C.; Tabak, Max; Libby, Stephen B.; Baring, Matthew G.

    2014-01-01

    The interaction of petawatt (1015 W) lasers with solid matter forms the basis for advanced scientific applications such as table-top particle accelerators, ultrafast imaging systems and laser fusion. Key metrics for these applications relate to absorption, yet conditions in this regime are so nonlinear that it is often impossible to know the fraction of absorbed light f, and even the range of f is unknown. Here using a relativistic Rankine-Hugoniot-like analysis, we show for the first time that f exhibits a theoretical maximum and minimum. These bounds constrain nonlinear absorption mechanisms across the petawatt regime, forbidding high absorption values at low laser power and low absorption values at high laser power. For applications needing to circumvent the absorption bounds, these results will accelerate a shift from solid targets, towards structured and multilayer targets, and lead the development of new materials. PMID:24938656

  16. [The study of CO2 cavity enhanced absorption and highly sensitive absorption spectroscopy].

    PubMed

    Pei, Shi-Xin; Gao, Xiao-Ming; Cui, Fen-Ping; Huang, Wei; Shao, Jie; Fan, Hong; Zhang, Wei-Jun

    2005-12-01

    Cavity enhanced absorption spectroscopy (CEAS) is a new spectral technology that is based on the cavity ring down absorption spectroscopy. In the present paper, a DFB encapsulation narrow line width tunable diode laser (TDL) was used as the light source. At the center output, the TDL radiation wavelength was 1.573 microm, and an optical cavity, which consisted of two high reflectivity mirrors (near 1.573 microm, the mirror reflectivity was about 0.994%), was used as a sample cell. A wavemeter was used to record the accurate frequency of the laser radiation. In the experiment, the method of scanning the optical cavity to change the cavity mode was used, when the laser frequency was coincident with one of the cavity mode; the laser radiation was coupled into the optical cavity and the detector could receive the light signals that escaped the optical cavity. As a result, the absorption spectrum of carbon dioxide weak absorption at low pressure was obtained with an absorption intensity of 1.816 x 10(-23) cm(-1) x (molecule x cm(-2)(-1) in a sample cell with a length of only 33.5 cm. An absorption sensitivity of about 3.62 x 10(-7) cm(-1) has been achieved. The experiment result indicated that the cavity enhanced absorption spectroscopy has the advantage of high sensivity, simple experimental setup, and easy operation.

  17. Au-rich filamentary behavior and associated subband gap optical absorption in hyperdoped Si

    NASA Astrophysics Data System (ADS)

    Yang, W.; Akey, A. J.; Smillie, L. A.; Mailoa, J. P.; Johnson, B. C.; McCallum, J. C.; Macdonald, D.; Buonassisi, T.; Aziz, M. J.; Williams, J. S.

    2017-12-01

    Au-hyperdoped Si, synthesized by ion implantation and pulsed laser melting, is known to exhibit a strong sub-band gap photoresponse that scales monotonically with the Au concentration. However, there is thought to be a limit to this behavior since ultrahigh Au concentrations (>1 ×1020c m-3 ) are expected to induce cellular breakdown during the rapid resolidification of Si, a process that is associated with significant lateral impurity precipitation. This work shows that the cellular morphology observed in Au-hyperdoped Si differs from that in conventional, steady-state cellular breakdown. In particular, Rutherford backscattering spectrometry combined with channeling and transmission electron microscopy revealed an inhomogeneous Au distribution and a subsurface network of Au-rich filaments, within which the Au impurities largely reside on substitutional positions in the crystalline Si lattice, at concentrations as high as ˜3 at. %. The measured substitutional Au dose, regardless of the presence of Au-rich filaments, correlates strongly with the sub-band gap optical absorptance. Upon subsequent thermal treatment, the supersaturated Au forms precipitates, while the Au substitutionality and the sub-band gap optical absorption both decrease. These results offer insight into a metastable filamentary regime in Au-hyperdoped Si that has important implications for Si-based infrared optoelectronics.

  18. Graphene oxide-TiO2 composite solid phase extraction combined with graphite furnace atomic absorption spectrometry for the speciation of inorganic selenium in water samples.

    PubMed

    Zhang, Yanan; Chen, Beibei; Wu, Shaowei; He, Man; Hu, Bin

    2016-07-01

    In this paper, a method of graphene oxide (GO)-TiO2 composite solid phase extraction followed by graphite furnace atomic absorption spectrometry (GFAAS) detection was proposed for the speciation of inorganic selenium in environmental waters. The adsorption behavior of inorganic Se(IV) and Se(VI) on the GO-TiO2(1:1) composite was investigated. It was found that Se(IV) was quantitatively retained on the GO-TiO2 composites within a wide pH range of 0.5-10, while Se(VI) was quantitatively adsorbed on GO-TiO2(1:1) composite at pH 0.5-2, and no obvious adsorption of Se(VI) within the pH range of 4-10 was found. By selecting pH 6.0, Se(IV) could be easily determined. After reduction of Se(VI), total Se was determined by the proposed method, and Se(VI) was calculated as the difference between the total Se and Se(IV). The factors affecting the separation/preconcentration of Se(IV) and Se(VI) were studied. Under the optimum conditions, the isothermal adsorption of Se(IV) on the GO-TiO2(1:1) composite fitted Langmuir model; a linear range over 0.1-12ngmL(-1) was obtained. The limit of detection (LOD) and precision of the method for Se(IV) was 0.04ngmL(-1) and 9.4% (cSe(IV)=0.5ngmL(-1), n=7), respectively. In order to verify the accuracy of the method, a standard water sample (GSBZ50031-94) was analyzed, and the determined value was in a good agreement to the certified value. The established method was applied to inorganic Se speciation in environmental water samples and the recovery of 87.4-102% was obtained for the spiked samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Preconcentration and determination of vanadium and molybdenum in milk, vegetables and foodstuffs by ultrasonic-thermostatic-assisted cloud point extraction coupled to flame atomic absorption spectrometry.

    PubMed

    Gürkan, Ramazan; Korkmaz, Sema; Altunay, Nail

    2016-08-01

    A new ultrasonic-thermostatic-assisted cloud point extraction procedure (UTA-CPE) was developed for preconcentration at the trace levels of vanadium (V) and molybdenum (Mo) in milk, vegetables and foodstuffs prior to determination via flame atomic absorption spectrometry (FAAS). The method is based on the ion-association of stable anionic oxalate complexes of V(V) and Mo(VI) with [9-(diethylamino)benzo[a]phenoxazin-5-ylidene]azanium; sulfate (Nile blue A) at pH 4.5, and then extraction of the formed ion-association complexes into micellar phase of polyoxyethylene(7.5)nonylphenyl ether (PONPE 7.5). The UTA-CPE is greatly simplified and accelerated compared to traditional cloud point extraction (CPE). The analytical parameters optimized are solution pH, the concentrations of complexing reagents (oxalate and Nile blue A), the PONPE 7.5 concentration, electrolyte concentration, sample volume, temperature and ultrasonic power. Under the optimum conditions, the calibration curves for Mo(VI) and V(V) are obtained in the concentration range of 3-340µgL(-1) and 5-250µgL(-1) with high sensitivity enhancement factors (EFs) of 145 and 115, respectively. The limits of detection (LODs) for Mo(VI) and V(V) are 0.86 and 1.55µgL(-1), respectively. The proposed method demonstrated good performances such as relative standard deviations (as RSD %) (≤3.5%) and spiked recoveries (95.7-102.3%). The accuracy of the method was assessed by analysis of two standard reference materials (SRMs) and recoveries of spiked solutions. The method was successfully applied into the determination of trace amounts of Mo(VI) and V(V) in milk, vegetables and foodstuffs with satisfactory results. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Determination of sub-ng g-1 levels of total inorganic arsenic and selenium in foods by hydride-generation atomic absorption spectrometry after pre-concentration.

    PubMed

    Altunay, Nail; Gürkan, Ramazan

    2017-03-01

    A new and simple ultrasonic-assisted extraction (UAE) procedure was developed for the determination of inorganic arsenic and selenium in foods by hydride-generation atomic absorption spectrometry (HG-AAS). The various analytical variables affecting complex formation and extraction efficiency were investigated and optimised. The method is based on selective complex formation of As(III) and Se(IV) in the presence of excess As(V) and Se(VI) with toluidine red in the presence of tartaric acid at pH 4.5, and then extraction of the resulting condensation products into the micellar phase of non-ionic surfactant, polyethylene glycol dodecyl ether, Brij 35. Under optimised conditions, good linear relationships were obtained in the ranges of 4-225 and 12-400 ng l - 1 with limits of detection of 1.1 and 3.5 ng l - 1 for As(III) and Se(IV), respectively. The repeatability was better than 3.9% for both analytes (n = 10, 25 ng l - 1 ) while reproducibility ranged from 4.2% to 4.8%. The recoveries of As(III) and Se(IV) spiked at 25-100 ng l - 1 were in the range of 94.2-104.8%. After pre-concentration of a 5.0 ml sample, the sensitivity enhancement factors for As(III) and Se(IV) were 185 and 140, respectively. Accuracy was assessed by analysis of two standard reference materials (SRMs) and spiked recovery experiments. The method was successfully applied to the accurate and reliable determination of total As and total Se by HG-AAS after pre-reduction with a mixture of L-cysteine and tartaric acid. Finally, the method was shown to be rapid and sensitive, with good results for extraction, pre-concentration and determination of total As and Se contents (as As(III) and Se(IV)) from food samples.

  1. Determination of fluorine by total reflection X-ray fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Tarsoly, G.; Óvári, M.; Záray, Gy.

    2010-04-01

    There is a growing interest in determination of low Z elements, i.e. carbon to phosphorus, in various samples. Total reflection X-ray fluorescence spectrometry (TXRF) has been already established as a suitable trace element analytical method with low sample demand and quite good quantification limits. Recently, the determinable element range was extended towards Z = 6 (carbon). In this study, the analytical performance of the total reflection X-ray fluorescence spectrometry for determination of fluorine was investigated applying a spectrometer equipped with Cr-anode X-ray tube, multilayer monochromator, vacuum chamber, and a silicon drift detector (SDD) with ultra thin window was used. The detection limit for fluorine was found to be 5 mg L - 1 (equivalent to 10 ng absolute) in aqueous matrix. The linear range of the fluorine determination is between 15 and 500 mg L - 1 , within this range the precision is below 10%. The matrix effects of the other halogens (chlorine, bromine and iodine), and sulfate were also investigated. It has been established that the upper allowed concentration limit of the above interfering elements is 100, 200, 50 and 100 mg L - 1 for Cl, Br, I and sulfate, respectively. Moreover, the role of the pre-siliconization of the quartz carrier plate was investigated. It was found, that the presence of the silicone results in poorer analytical performance, which can be explained by the thicker sample residue and stronger self-absorption of the fluorescent radiation.

  2. In vivo measurement of human skin absorption of topically applied substances by a photoacoustic technique.

    PubMed

    Gutiérrez-Juárez, G; Vargas-Luna, M; Córdova, T; Varela, J B; Bernal-Alvarado, J J; Sosa, M

    2002-08-01

    A photoacoustic technique is used for studying topically applied substance absorption in human skin. The proposed method utilizes a double-chamber PA cell. The absorption determination was obtained through the measurement of the thermal effusivity of the binary system substance-skin. The theoretical model assumes that the effective thermal effusivity of the binary system corresponds to that of a two-phase system. Experimental applications of the method employed different substances of topical application in different parts of the body of a volunteer. The method is demonstrated to be an easily used non-invasive technique for dermatology research. The relative concentrations as a function of time of substances such as ketoconazol and sunscreen were determined by fitting a sigmoidal function to the data, while an exponential function corresponds to the best fit for the set of data for nitrofurazona, vaseline and vaporub. The time constants associated with the rates of absorption, were found to vary in the range between 10 and 58 min, depending on the substance and the part of the body.

  3. Characterization of low-molecular weight iodine-terminated polyethylenes by gas chromatography/mass spectrometry and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with the use of derivatization.

    PubMed

    Zaikin, Vladimir G; Borisov, Roman S; Polovkov, Nikolai Yu; Zhilyaev, Dmitry I; Vinogradov, Aleksei A; Ivanyuk, Aleksei V

    2013-01-01

    Gas chromatography/mass spectrometry (GC/MS) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-ToF) mass spectrometry, in conjunction with various derivatization approaches, have been applied to structure determination of individual oligomers and molecular-mass distributions (MMD) in low-molecular mass polyethylene having an iodine terminus. Direct GC/MS analysis has shown that the samples under investigation composed of polyethyelene-iodides (major components) and n-alkanes. Exchange reaction with methanol in the presence of NaOH gave rise to methoxy-derivatives and n-alkenes. Electron ionization mass spectra have shown that the former contained terminal methoxy groups indicating the terminal position of the iodine atom in the initial oligomers. MMD parameters have been determined with the aid of MALDI mass spectrometry followed by preliminary derivatization-formation of covalently bonded charge through the reaction of iodides with triphenylphosphine, trialkylamines, pyridine or quinoline. The mass spectra revealed well-resolved peaks for cationic parts of derivatized oligomers allowing the determination of MMD. The latter values have been compared with those calculated from GC/MS data.

  4. Selective and sensitive speciation analysis of Cr(VI) and Cr(III), at sub-μgL-1 levels in water samples by electrothermal atomic absorption spectrometry after electromembrane extraction.

    PubMed

    Tahmasebi, Zeinab; Davarani, Saied Saeed Hosseiny

    2016-12-01

    In this work, electromembrane extraction in combination with electrothermal atomic absorption spectrometry (ET-AAS) was investigated for speciation, preconcentration and quantification of Cr(VI) and Cr(III) in water samples through the selective complexation of Cr(VI) with 1,5-diphenylcarbazide (DPC) as a complexing agent. DPC reduces Cr(VI) to Cr(III) ions and then Cr(III) species are extracted based on electrokinetic migration of their cationic complex (Cr(III)-DPC) toward the negative electrode placed in the hollow fiber. Also, once oxidized to Cr(VI), Cr(III) ions in initial sample were determined by this procedure. The influence of extraction parameters such as pH, type of organic solvent, chelating agent concentration, stirring rate, extraction time and applied voltage were evaluated following a one-at-a-time optimization approach. Under optimized conditions, the extracted analyte was quantified by ETAAS, with an acceptable linearity in the range of 0.05-5ngmL -1 (R 2 value=0.996), and a repeatability (%RSD) between 3.7% and 12.2% (n=4) for 5.0 and 1.0ngmL -1 of Cr(VI), respectively. Also, we obtained an enrichment factor of 110 that corresponded to the recovery of 66%. The detection limit (S/N ratio of 3:1) was 0.02ngmL -1 . Finally, this new method was successfully employed to determine Cr(III) and Cr(VI) species in real water samples. Copyright © 2016. Published by Elsevier B.V.

  5. Advances in explosives analysis—part I. animal, chemical, ion, and mechanical methods

    DOE PAGES

    Brown, Kathryn E.; Greenfield, Margo T.; McGrane, Shawn D.; ...

    2015-10-13

    The number and capability of explosives detection and analysis methods have increased substantially since the publication of the Analytical and Bioanalytical Chemistry special issue devoted to Explosives Analysis (Moore and Goodpaster, Anal Bioanal Chem 395(2):245–246, 2009). We review and critically evaluate the latest (the past five years) important advances in explosives detection, with details of the improvements over previous methods, and suggest possible avenues towards further advances in, e.g., stand-off distance, detection limit, selectivity, and penetration through camouflage or packaging. The review consists of two parts. Moreover, Part I, reviews methods based on animals, chemicals (including colorimetry, molecularly imprinted polymers,more » electrochemistry, and immunochemistry), ions (both ion-mobility spectrometry and mass spectrometry), and mechanical devices. Part II will review methods based on photons, from very energetic photons including X-rays and gamma rays down to the terahertz range, and neutrons.« less

  6. Guidelines for reporting quantitative mass spectrometry based experiments in proteomics.

    PubMed

    Martínez-Bartolomé, Salvador; Deutsch, Eric W; Binz, Pierre-Alain; Jones, Andrew R; Eisenacher, Martin; Mayer, Gerhard; Campos, Alex; Canals, Francesc; Bech-Serra, Joan-Josep; Carrascal, Montserrat; Gay, Marina; Paradela, Alberto; Navajas, Rosana; Marcilla, Miguel; Hernáez, María Luisa; Gutiérrez-Blázquez, María Dolores; Velarde, Luis Felipe Clemente; Aloria, Kerman; Beaskoetxea, Jabier; Medina-Aunon, J Alberto; Albar, Juan P

    2013-12-16

    Mass spectrometry is already a well-established protein identification tool and recent methodological and technological developments have also made possible the extraction of quantitative data of protein abundance in large-scale studies. Several strategies for absolute and relative quantitative proteomics and the statistical assessment of quantifications are possible, each having specific measurements and therefore, different data analysis workflows. The guidelines for Mass Spectrometry Quantification allow the description of a wide range of quantitative approaches, including labeled and label-free techniques and also targeted approaches such as Selected Reaction Monitoring (SRM). The HUPO Proteomics Standards Initiative (HUPO-PSI) has invested considerable efforts to improve the standardization of proteomics data handling, representation and sharing through the development of data standards, reporting guidelines, controlled vocabularies and tooling. In this manuscript, we describe a key output from the HUPO-PSI-namely the MIAPE Quant guidelines, which have developed in parallel with the corresponding data exchange format mzQuantML [1]. The MIAPE Quant guidelines describe the HUPO-PSI proposal concerning the minimum information to be reported when a quantitative data set, derived from mass spectrometry (MS), is submitted to a database or as supplementary information to a journal. The guidelines have been developed with input from a broad spectrum of stakeholders in the proteomics field to represent a true consensus view of the most important data types and metadata, required for a quantitative experiment to be analyzed critically or a data analysis pipeline to be reproduced. It is anticipated that they will influence or be directly adopted as part of journal guidelines for publication and by public proteomics databases and thus may have an impact on proteomics laboratories across the world. This article is part of a Special Issue entitled: Standardization and

  7. Reactivity of Chromium(III) Nutritional Supplements in Biological Media: An X-Ray Absorption Spectroscopic Study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nguyen, A.; Mulyani, I.; Levina, A.

    2009-05-22

    Chromium(III) nutritional supplements are widely used due to their purported ability to enhance glucose metabolism, despite growing evidence on low activity and the potential genotoxicity of these compounds. Reactivities of Cr(III) complexes used in nutritional formulations, including [Cr3O(OCOEt)6(OH2)3]+ (A), [Cr(pic)3] (pic) = 2-pyridinecarboxylato(-) (B), and trans-[CrCl2(OH2)4]+ (CrCl3 {center_dot} 6H2O; C), in a range of natural and simulated biological media (artificial digestion systems, blood and its components, cell culture media, and intact L6 rat skeletal muscle cells) were studied by X-ray absorption near-edge structure (XANES) spectroscopy. The XANES spectroscopic data were processed by multiple linear-regression analyses with the use of amore » library of model Cr(III) compounds, and the results were corroborated by the results of X-ray absorption fine structure spectroscopy and electrospray mass spectrometry. Complexes A and B underwent extensive ligand-exchange reactions under conditions of combined gastric and intestinal digestion (in the presence of a semisynthetic meal, 3 h at 310 K), as well as in blood serum and in a cell culture medium (1-24 h at 310 K), with the formation of Cr(III) complexes with hydroxo and amino acid/protein ligands. Reactions of compounds A-C with cultured muscle cells led to similar ligand-exchange products, with at least part of Cr(III) bound to the surface of the cells. The reactions of B with serum greatly enhanced its propensity to be converted to Cr(VI) by biological oxidants (H2O2 or glucose oxidase system), which is proposed to be a major cause of both the insulin-enhancing activity and toxicity of Cr(III) compounds (Mulyani, I.; Levina, A.; Lay, P. A. Angew. Chem. Int. Ed. 2004, 43, 4504-4507). This finding enhances the current concern over the safety of consumption of large doses of Cr(III) supplements, particularly [Cr(pic)3].« less

  8. Arsenic in marine tissues — The challenging problems to electrothermal and hydride generation atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Karadjova, Irina B.; Petrov, Panayot K.; Serafimovski, Ivan; Stafilov, Trajče; Tsalev, Dimiter L.

    2007-03-01

    Analytical problems in determination of arsenic in marine tissues are addressed. Procedures for the determination of total As in solubilized or extracted tissues with tetramethylammonium hydroxide and methanol have been elaborated. Several typical lyophilized tissues were used: NIST SRM 1566a 'Oyster Tissue', BCR-60 CRM 'Trace Elements in an Aquatic Plant ( Lagarosiphon major)', BCR-627 'Forms of As in Tuna Fish Tissue', IAEA-140/TM 'Sea Plant Homogenate', NRCC DOLT-1 'Dogfish Liver' and two representatives of the Black Sea biota, Mediterranean mussel ( Mytilus galloprovincialis) and Brown algae ( Cystoseira barbata). Tissues (nominal 0.3 g) were extracted in tetramethylammonium hydroxide (TMAH) 1 ml of 25% m/v TMAH and 2 ml of water) or 5 ml of aqueous 80% v/v methanol (MeOH) in closed vessels in a microwave oven at 50 °C for 30 min. Arsenic in solubilized or extracted tissues was determined by electrothermal atomic absorption spectrometry (ETAAS) after appropriate dilution (nominally to 25 ml, with further dilution as required) under optimal instrumental parameters (pyrolysis temperature 900 °C and atomization temperature 2100 °C) with 1.5 μg Pd as modifier on Zr-Ir treated platform. Platforms have been pre-treated with 2.7 μmol of zirconium and then with 0.10 μmol of iridium which served as a permanent chemical modifier in direct ETAAS measurements and as an efficient hydride sequestration medium in flow injection hydride generation (FI-HG)-ETAAS. TMAH and methanol extract 96-108% and 51-100% of As from CRMs. Various calibration approaches have been considered and critically evaluated. The effect of species-dependent slope of calibration graph or standard additions plot for total As determination in a sample comprising of several individual As species with different ETAAS behavior has been considered as a kind of 'intrinsic element speciation interference' that cannot be completely overcome by standard additions technique. Calibration by means of CRMs has

  9. Identification of Microalgae by Laser Desorption/Ionization Mass Spectrometry Coupled with Multiple Nanomatrices.

    PubMed

    Peng, Lung-Hsiang; Unnikrishnan, Binesh; Shih, Chi-Yu; Hsiung, Tung-Ming; Chang, Jeng; Hsu, Pang-Hung; Chiu, Tai-Chia; Huang, Chih-Ching

    2016-04-01

    In this study, we demonstrate a simple method to identify microalgae by surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) using three different substrates: HgSe, HgTe, and HgTeSe nanostructures. The fragmentation/ionization processes of complex molecules in algae varied according to the heat absorption and transfer efficiency of the nanostructured matrices (NMs). Therefore, the mass spectra obtained for microalgae showed different patterns of m/z values for different NMs. The spectra contained both significant and nonsignificant peaks. Constructing a Venn diagram with the significant peaks obtained for algae when using HgSe, HgTe, and HgTeSe NMs in m/z ratio range 100-1000, a unique relationship among the three sets of values was obtained. This unique relationship of sets is different for each species of microalgae. Therefore, by observing the particular relationship of sets, we successfully identified different algae such as Isochrysis galbana, Emiliania huxleyi, Thalassiosira weissflogii, Nannochloris sp., Skeletonema cf. costatum, and Tetraselmis chui. This simple and cost-effective SALDI-MS analysis method coupled with multi-nanomaterials as substrates may be extended to identify other microalgae and microorganisms in real samples. Graphical Abstract Identification of microalgae by surface-assisted laser desorption/ionization mass spectrometry coupled with three different mercury-based nanosubstrates.

  10. Plasma sterol evidence for decreased absorption and increased synthesis of cholesterol in insulin resistance and obesity1234

    PubMed Central

    Knopp, Robert H; Kahn, Steven E; Retzlaff, Barbara M; Fish, Brian; Ma, Lina; Ostlund, Richard E

    2011-01-01

    Background: The rise in LDL with egg feeding in lean insulin-sensitive (LIS) participants is 2- and 3-fold greater than in lean insulin-resistant (LIR) and obese insulin-resistant (OIR) participants, respectively. Objective: We determined whether differences in cholesterol absorption, synthesis, or both could be responsible for these differences by measuring plasma sterols as indexes of cholesterol absorption and endogenous synthesis. Design: Plasma sterols were measured by gas chromatography–mass spectrometry in a random subset of 34 LIS, 37 LIR, and 37 OIR participants defined by the insulin sensitivity index (SI) and by BMI criteria selected from a parent group of 197 participants. Cholestanol and plant sterols provide a measure of cholesterol absorption, and lathosterol provides a measure of cholesterol synthesis. Results: The mean (±SD) ratio of plasma total absorption biomarker sterols to cholesterol was 4.48 ± 1.74 in LIS, 3.25 ± 1.06 in LIR, and 2.82 ± 1.08 in OIR participants. After adjustment for age and sex, the relations of the absorption sterol–cholesterol ratios were as follows: LIS > OIR (P < 0.001), LIS > LIR (P < 0.001), and LIR > OIR (P = 0.11). Lathosterol-cholesterol ratios were 0.71 ± 0.32 in the LIS participants, 0.95 ± 0.47 in the LIR participants, and 1.29 ± 0.55 in the OIR participants. After adjustment for age and sex, the relations of lathosterol-cholesterol ratios were as follows: LIS < OIR (P < 0.001), LIS < LIR (P = 0.03), and LIR < OIR (P = 0.002). Total sterol concentrations were positively associated with SI and negatively associated with obesity, whereas lathosterol correlations were the opposite. Conclusions: Cholesterol absorption was highest in the LIS participants, whereas cholesterol synthesis was highest in the LIR and OIR participants. Therapeutic diets for hyperlipidemia should emphasize low-cholesterol diets in LIS persons and weight loss to improve SI and to decrease cholesterol overproduction in LIR and OIR

  11. Terahertz absorption in graphite nanoplatelets/polylactic acid composites

    NASA Astrophysics Data System (ADS)

    Bychanok, D.; Angelova, P.; Paddubskaya, A.; Meisak, D.; Shashkova, L.; Demidenko, M.; Plyushch, A.; Ivanov, E.; Krastev, R.; Kotsilkova, R.; Ogrin, F. Y.; Kuzhir, P.

    2018-04-01

    The electromagnetic properties of composite materials based on poly(lactic) acid (PLA) filled with graphite nanoplatelets (GNP) were investigated in the microwave (26–37 GHz) and terahertz (0.2–1 THz) frequency ranges. The maximum of the imaginary part of the dielectric permittivity was observed close to 0.6 THz for composites with 1.5 and 3 wt.% of GNP. The experimental data of complex dielectric permittivity of GNP/PLA composites was modelled using the Maxwell-Garnett theory. The effects of fine dispersion, agglomeration, and percolation in GNP-based composites on its electromagnetic constitutive parameters, presence, and position of THz absorption peak are discussed on the basis of the modeling results and experimental data. The unique combination of conductive and geometrical parameters of GNP embedded into the PLA matrix below the percolation threshold allow us to obtain the THz-absorptive material, which may be effectively used as a 3D-printing filament.

  12. Metal powder absorptivity: Modeling and experiment

    DOE PAGES

    Boley, C. D.; Mitchell, S. C.; Rubenchik, A. M.; ...

    2016-08-10

    Here, we present results of numerical modeling and direct calorimetric measurements of the powder absorptivity for a number of metals. The modeling results generally correlate well with experiment. We show that the powder absorptivity is determined, to a great extent, by the absorptivity of a flat surface at normal incidence. Our results allow the prediction of the powder absorptivity from normal flat-surface absorptivity measurements.

  13. Metal powder absorptivity: Modeling and experiment

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Boley, C. D.; Mitchell, S. C.; Rubenchik, A. M.

    Here, we present results of numerical modeling and direct calorimetric measurements of the powder absorptivity for a number of metals. The modeling results generally correlate well with experiment. We show that the powder absorptivity is determined, to a great extent, by the absorptivity of a flat surface at normal incidence. Our results allow the prediction of the powder absorptivity from normal flat-surface absorptivity measurements.

  14. Characterizing the lipid and metabolite changes associated with placental function and pregnancy complications using ion mobility spectrometry-mass spectrometry and mass spectrometry imaging

    DOE PAGES

    Burnum-Johnson, Kristin E.; Baker, Erin S.; Metz, Thomas O.

    2017-03-29

    A successful pregnancy is dependent upon discrete biological events, which include embryo implantation, decidualization, and placentation. Furthermore, problems associated with each of these events can cause infertility or conditions such as preeclampsia. A greater understanding of the molecular changes associated with these complex processes is necessary to aid in identifying treatments for each condition. Previous nuclear magnetic resonance spectroscopy and mass spectrometry studies have been used to identify metabolites and lipids associated with pregnancy-related complications. However, due to limitations associated with conventional implementations of both techniques, novel technology developments are needed to more fully understand the initiation and development ofmore » pregnancy related problems at the molecular level. Here, we describe current analytical techniques for metabolomic and lipidomic characterization of pregnancy complications and discuss the potential for new technologies such as ion mobility spectrometry-mass spectrometry and mass spectrometry imaging to contribute to a better understanding of the molecular changes that affect the placenta and pregnancy outcomes.« less

  15. Characterizing the lipid and metabolite changes associated with placental function and pregnancy complications using ion mobility spectrometry-mass spectrometry and mass spectrometry imaging

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Burnum-Johnson, Kristin E.; Baker, Erin S.; Metz, Thomas O.

    Successful pregnancy is dependent upon discrete biological events, which include embryo implantation, decidualization, and placentation. Problems associated with each of these events can cause infertility or conditions such as preeclampsia. A greater understanding of the molecular changes associated with these complex processes is necessary to aid in identifying treatments for each condition. Previous nuclear magnetic resonance spectroscopy and mass spectrometry studies have been used to identify metabolites and lipids associated with pregnancy-related complications. However, due to limitations associated with conventional implementations of both techniques, novel technology developments are needed to more fully understand the initiation and development of pregnancy relatedmore » problems at the molecular level. In this perspective, we describe current analytical techniques for metabolomic and lipidomic characterization of pregnancy complications and discuss the potential for new technologies such as ion mobility spectrometry-mass spectrometry and mass spectrometry imaging to contribute to a better understanding of the molecular changes that affect the placenta and pregnancy outcomes.« less

  16. Characterizing the lipid and metabolite changes associated with placental function and pregnancy complications using ion mobility spectrometry-mass spectrometry and mass spectrometry imaging

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Burnum-Johnson, Kristin E.; Baker, Erin S.; Metz, Thomas O.

    A successful pregnancy is dependent upon discrete biological events, which include embryo implantation, decidualization, and placentation. Furthermore, problems associated with each of these events can cause infertility or conditions such as preeclampsia. A greater understanding of the molecular changes associated with these complex processes is necessary to aid in identifying treatments for each condition. Previous nuclear magnetic resonance spectroscopy and mass spectrometry studies have been used to identify metabolites and lipids associated with pregnancy-related complications. However, due to limitations associated with conventional implementations of both techniques, novel technology developments are needed to more fully understand the initiation and development ofmore » pregnancy related problems at the molecular level. Here, we describe current analytical techniques for metabolomic and lipidomic characterization of pregnancy complications and discuss the potential for new technologies such as ion mobility spectrometry-mass spectrometry and mass spectrometry imaging to contribute to a better understanding of the molecular changes that affect the placenta and pregnancy outcomes.« less

  17. A highly selective and sensitive ultrasonic assisted dispersive liquid phase microextraction based on deep eutectic solvent for determination of cadmium in food and water samples prior to electrothermal atomic absorption spectrometry.

    PubMed

    Zounr, Rizwan Ali; Tuzen, Mustafa; Deligonul, Nihal; Khuhawar, Muhammad Yar

    2018-07-01

    A simple, fast, green, sensitive and selective ultrasonic assisted deep eutectic solvent liquid-phase microextraction technique was used for preconcentration and extraction of cadmium (Cd) in water and food samples by electrothermal atomic absorption spectrometry (ETAAS). In this technique, a synthesized reagent (Z)-N-(3,5-diphenyl-1H-pyrrol-2-yl)-3,5-diphenyl-2H-pyrrol-2-imine (Azo) was used as a complexing agent for Cd. The main factors effecting the pre-concentration and extraction of Cd such as effect of pH, type and composition of deep eutectic solvent (DES), volume of DES, volume of complexing agent, volume of tetrahydrofuran (THF) and ultrasonication time have been examined in detail. At optimum conditions the value of pH and molar ratio of DES were found to be 6.0 and 1:4 (ChCl:Ph), respectively. The detection limit (LOD), limit of quantification (LOQ), relative standard deviation (RSD) and preconcentration factor (PF) were observed as 0.023 ng L -1 , 0.161 ng L -1 , 3.1% and 100, correspondingly. Validation of the developed technique was observed by extraction of Cd in certified reference materials (CRMs) and observed results were successfully compared with certified values. The developed procedure was practiced to various food, beverage and water samples. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. Time-dependent oral absorption models

    NASA Technical Reports Server (NTRS)

    Higaki, K.; Yamashita, S.; Amidon, G. L.

    2001-01-01

    The plasma concentration-time profiles following oral administration of drugs are often irregular and cannot be interpreted easily with conventional models based on first- or zero-order absorption kinetics and lag time. Six new models were developed using a time-dependent absorption rate coefficient, ka(t), wherein the time dependency was varied to account for the dynamic processes such as changes in fluid absorption or secretion, in absorption surface area, and in motility with time, in the gastrointestinal tract. In the present study, the plasma concentration profiles of propranolol obtained in human subjects following oral dosing were analyzed using the newly derived models based on mass balance and compared with the conventional models. Nonlinear regression analysis indicated that the conventional compartment model including lag time (CLAG model) could not predict the rapid initial increase in plasma concentration after dosing and the predicted Cmax values were much lower than that observed. On the other hand, all models with the time-dependent absorption rate coefficient, ka(t), were superior to the CLAG model in predicting plasma concentration profiles. Based on Akaike's Information Criterion (AIC), the fluid absorption model without lag time (FA model) exhibited the best overall fit to the data. The two-phase model including lag time, TPLAG model was also found to be a good model judging from the values of sum of squares. This model also described the irregular profiles of plasma concentration with time and frequently predicted Cmax values satisfactorily. A comparison of the absorption rate profiles also suggested that the TPLAG model is better at prediction of irregular absorption kinetics than the FA model. In conclusion, the incorporation of a time-dependent absorption rate coefficient ka(t) allows the prediction of nonlinear absorption characteristics in a more reliable manner.

  19. Intestinal Water Absorption Varies with Expected Dietary Water Load among Bats but Does Not Drive Paracellular Nutrient Absorption.

    PubMed

    Price, Edwin R; Brun, Antonio; Gontero-Fourcade, Manuel; Fernández-Marinone, Guido; Cruz-Neto, Ariovaldo P; Karasov, William H; Caviedes-Vidal, Enrique

    2015-01-01

    Rapid absorption and elimination of dietary water should be particularly important to flying species and were predicted to vary with the water content of the natural diet. Additionally, high water absorption capacity was predicted to be associated with high paracellular nutrient absorption due to solvent drag. We compared the water absorption rates of sanguivorous, nectarivorous, frugivorous, and insectivorous bats in intestinal luminal perfusions. High water absorption rates were associated with high expected dietary water load but were not highly correlated with previously measured rates of (paracellular) arabinose clearance. In conjunction with these tests, we measured water absorption and the paracellular absorption of nutrients in the intestine and stomach of vampire bats using luminal perfusions to test the hypothesis that the unique elongated vampire stomach is a critical site of water absorption. Vampire bats' gastric water absorption was high compared to mice but not compared to their intestines. We therefore conclude that (1) dietary water content has influenced the evolution of intestinal water absorption capacity in bats, (2) solvent drag is not the only driver of paracellular nutrient absorption, and (3) the vampire stomach is a capable but not critical location for water absorption.

  20. Inorganic trace analysis by mass spectrometry

    NASA Astrophysics Data System (ADS)

    Becker, Johanna Sabine; Dietze, Hans-Joachim

    1998-10-01

    Mass spectrometric methods for the trace analysis of inorganic materials with their ability to provide a very sensitive multielemental analysis have been established for the determination of trace and ultratrace elements in high-purity materials (metals, semiconductors and insulators), in different technical samples (e.g. alloys, pure chemicals, ceramics, thin films, ion-implanted semiconductors), in environmental samples (waters, soils, biological and medical materials) and geological samples. Whereas such techniques as spark source mass spectrometry (SSMS), laser ionization mass spectrometry (LIMS), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), glow discharge mass spectrometry (GDMS), secondary ion mass spectrometry (SIMS) and inductively coupled plasma mass spectrometry (ICP-MS) have multielemental capability, other methods such as thermal ionization mass spectrometry (TIMS), accelerator mass spectrometry (AMS) and resonance ionization mass spectrometry (RIMS) have been used for sensitive mono- or oligoelemental ultratrace analysis (and precise determination of isotopic ratios) in solid samples. The limits of detection for chemical elements using these mass spectrometric techniques are in the low ng g -1 concentration range. The quantification of the analytical results of mass spectrometric methods is sometimes difficult due to a lack of matrix-fitted multielement standard reference materials (SRMs) for many solid samples. Therefore, owing to the simple quantification procedure of the aqueous solution, inductively coupled plasma mass spectrometry (ICP-MS) is being increasingly used for the characterization of solid samples after sample dissolution. ICP-MS is often combined with special sample introduction equipment (e.g. flow injection, hydride generation, high performance liquid chromatography (HPLC) or electrothermal vaporization) or an off-line matrix separation and enrichment of trace impurities (especially for characterization of