Sample records for absorption spectrometry measurements

  1. 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.

  2. 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)…

  3. 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.

  4. 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

  5. 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

  6. 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

  7. 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...

  8. 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…

  9. 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

  10. 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).

  11. 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.

  12. 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.

  13. 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,…

  14. [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.

  15. 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.

  16. 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

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. [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.

  3. 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.

  4. 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...

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. [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.

  15. [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.

  16. 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.

  17. 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.

  18. 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

  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. 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%.

  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. 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)

  3. 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).

  4. 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.

  5. 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

  6. 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.

  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. Models of filter-based particle light absorption measurements

    NASA Astrophysics Data System (ADS)

    Hamasha, Khadeejeh M.

    Light absorption by aerosol is very important in the visible, near UN, and near I.R region of the electromagnetic spectrum. Aerosol particles in the atmosphere have a great influence on the flux of solar energy, and also impact health in a negative sense when they are breathed into lungs. Aerosol absorption measurements are usually performed by filter-based methods that are derived from the change in light transmission through a filter where particles have been deposited. These methods suffer from interference between light-absorbing and light-scattering aerosol components. The Aethalometer is the most commonly used filter-based instrument for aerosol light absorption measurement. This dissertation describes new understanding of aerosol light absorption obtained by the filter method. The theory uses a multiple scattering model for the combination of filter and particle optics. The theory is evaluated using Aethalometer data from laboratory and ambient measurements in comparison with photoacoustic measurements of aerosol light absorption. Two models were developed to calculate aerosol light absorption coefficients from the Aethalometer data, and were compared to the in-situ aerosol light absorption coefficients. The first is an approximate model and the second is a "full" model. In the approximate model two extreme cases of aerosol optics were used to develop a model-based calibration scheme for the 7-wavelength Aethalometer. These cases include those of very strong scattering aerosols (Ammonium sulfate sample) and very absorbing aerosols (kerosene soot sample). The exponential behavior of light absorption in the strong multiple scattering limit is shown to be the square root of the total absorption optical depth rather than linear with optical depth as is commonly assumed with Beer's law. 2-stream radiative transfer theory was used to develop the full model to calculate the aerosol light absorption coefficients from the Aethalometer data. This comprehensive model

  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. High temperature measurement of water vapor absorption

    NASA Technical Reports Server (NTRS)

    Keefer, Dennis; Lewis, J. W. L.; Eskridge, Richard

    1985-01-01

    An investigation was undertaken to measure the absorption coefficient, at a wavelength of 10.6 microns, for mixtures of water vapor and a diluent gas at high temperature and pressure. The experimental concept was to create the desired conditions of temperature and pressure in a laser absorption wave, similar to that which would be created in a laser propulsion system. A simplified numerical model was developed to predict the characteristics of the absorption wave and to estimate the laser intensity threshold for initiation. A non-intrusive method for temperature measurement utilizing optical laser-beam deflection (OLD) and optical spark breakdown produced by an excimer laser, was thoroughly investigated and found suitable for the non-equilibrium conditions expected in the wave. Experiments were performed to verify the temperature measurement technique, to screen possible materials for surface initiation of the laser absorption wave and to attempt to initiate an absorption wave using the 1.5 kW carbon dioxide laser. The OLD technique was proven for air and for argon, but spark breakdown could not be produced in helium. It was not possible to initiate a laser absorption wave in mixtures of water and helium or water and argon using the 1.5 kW laser, a result which was consistent with the model prediction.

  12. 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.

  13. 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.

  14. Examination of the Measurement of Absorption Using the Reverberant Room Method for Highly Absorptive Acoustic Foam

    NASA Technical Reports Server (NTRS)

    Hughes, William O.; McNelis, Anne M.; Chris Nottoli; Eric Wolfram

    2015-01-01

    The absorption coefficient for material specimens are needed to quantify the expected acoustic performance of that material in its actual usage and environment. The ASTM C423-09a standard, "Standard Test Method for Sound Absorption and Sound Absorption Coefficients by the Reverberant Room Method" is often used to measure the absorption coefficient of material test specimens. This method has its basics in the Sabine formula. Although widely used, the interpretation of these measurements are a topic of interest. For example, in certain cases the measured Sabine absorption coefficients are greater than 1.0 for highly absorptive materials. This is often attributed to the diffraction edge effect phenomenon. An investigative test program to measure the absorption properties of highly absorbent melamine foam has been performed at the Riverbank Acoustical Laboratories. This paper will present and discuss the test results relating to the effect of the test materials' surface area, thickness and edge sealing conditions. A follow-on paper is envisioned that will present and discuss the results relating to the spacing between multiple piece specimens, and the mounting condition of the test specimen.

  15. 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...

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. Techniques For Measuring Absorption Coefficients In Crystalline Materials

    NASA Astrophysics Data System (ADS)

    Klein, Philipp H.

    1981-10-01

    Absorption coefficients smaller than 0.001 cm-1 can, with more or less difficulty, be measured by several techniques. With diligence, all methods can be refined to permit measurement of absorption coefficients as small as 0.00001 cm-1. Spectral data are most readily obtained by transmission (spectrophotometric) methods, using multiple internal reflection to increase effective sample length. Emissivity measurements, requiring extreme care in the elimination of detector noise and stray light, nevertheless afford the most accessible spectral data in the 0.0001 to 0.00001 cm-1 range. Single-wavelength informa-tion is most readily obtained with modifications of laser calorimetry. Thermo-couple detection of energy absorbed from a laser beam is convenient, but involves dc amplification techniques and is susceptible to stray-light problems. Photoacoustic detection, using ac methods, tends to diminish errors of these types, but at some expense in experimental complexity. Laser calorimetry has been used for measurements of absorption coefficients as small as 0.000003 cm-1. Both transmission and calorimetric data, taken as functions of intensity, have been used for measurement of nonlinear absorption coefficients.

  2. 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.

  3. 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).

  4. 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

  5. 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.

  6. Photothermal measurement of optical surface absorption using strain transducers

    NASA Astrophysics Data System (ADS)

    Leslie, D. H.; Trusty, G. L.

    1981-09-01

    We discuss the measurement of small optical surface absorption coefficients. A demonstration experiment was performed using a metallurgical strain gauge to measure 488 nm absorption on the surface of a glass plate. A strain of 10 to the minus 8th power resulted from absorption of 0.3 watts. The results are interpreted and the sensitivity of a proposed fiber optic strain gauge is discussed.

  7. [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.

  8. 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.

  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. 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

  11. 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

  12. 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.

  13. 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.

  14. Low-frequency sound absorption measurements in air

    NASA Technical Reports Server (NTRS)

    Zuckerwar, A. J.; Meredith, R. W.

    1984-01-01

    Thirty sets of sound absorption measurements in air at a pressure of 1 atmosphere are presented at temperatures from 10 C to 50 C, relative humidities from 0 to 100 percent, and frequencies from 10 to 2500 Hz. The measurements were conducted by the method of free decay in a resonant tube having a length of 18.261 m and bore diameter of 0.152 m. Background measurements in a gas consisting of 89.5 percent N2 and 10.5 percent Ar, a mixture which has the same sound velocity as air, permitted the wall and structural losses of the tube to be separated from the constituent absorption, consisting of classical rotational and vibrational absorption, in the air samples. The data were used to evaluate the vibrational relaxation frequencies of N2 and/or O2 for each of the 30 sets of meteorological parameters. Over the full range of humidity, the measured relaxation frequencies of N2 in air lie between those specified by ANSI Standard S1.26-1978 and those measured earlier in binary N2H2O mixtures. The measured relaxation frequencies could be determined only at very low values of humidity, reveal a significant trend away from the ANSI standard, in agreement with a prior investigation.

  15. 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.

  16. Measurements of the Absorption by Auditorium SEATING—A Model Study

    NASA Astrophysics Data System (ADS)

    BARRON, M.; COLEMAN, S.

    2001-01-01

    One of several problems with seat absorption is that only small numbers of seats can be tested in standard reverberation chambers. One method proposed for reverberation chamber measurements involves extrapolation when the absorption coefficient results are applied to actual auditoria. Model seat measurements in an effectively large model reverberation chamber have allowed the validity of this extrapolation to be checked. The alternative barrier method for reverberation chamber measurements was also tested and the two methods were compared. The effect on the absorption of row-row spacing as well as absorption by small numbers of seating rows was also investigated with model seats.

  17. Single-shot measurement of nonlinear absorption and nonlinear refraction.

    PubMed

    Jayabalan, J; Singh, Asha; Oak, Shrikant M

    2006-06-01

    A single-shot method for measurement of nonlinear optical absorption and refraction is described and analyzed. A spatial intensity variation of an elliptical Gaussian beam in conjugation with an array detector is the key element of this method. The advantages of this single-shot technique were demonstrated by measuring the two-photon absorption and free-carrier absorption in GaAs as well as the nonlinear refractive index of CS2 using a modified optical Kerr setup.

  18. Pavement sound absorption measurements in the U.S.

    DOT National Transportation Integrated Search

    2012-08-19

    In the U.S., the topic of pavement sound absorption in regard to tire-pavement noise has shown increased interest and research over the last several years. Four types of pavement sound absorption measurements with various applications are discussed: ...

  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. 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.

  1. Measurement of HCl absorption coefficients with a DF laser

    NASA Technical Reports Server (NTRS)

    Bair, C. H.; Allario, F.

    1977-01-01

    Absorption coefficients in the fundamental P-branch of HCl at several DF laser transitions from 2439.02/cm to 2862.87/cm have been measured experimentally. The 2-1 P(3) DF laser transition has been shown to overlap the P(6) HCl-37 absorption line within the halfwidth of an atmospherically broadened line. The absorption coefficient k was measured to be 5.64 plus or minus 0.28/(atm-cm) for a 0.27% mixture of HCl in N2 at a total pressure of 760 torr. A theoretical and experimental comparison of the pressure dependence of k showed that the 2-1 P(3) DF transition lies 1.32 plus or minus 0.15 GHz from the center of the P(6) HCl absorption line. Applications of these results to differential absorption lidar and to heterodyne detection are discussed.

  2. Aerosol Absorption Measurements from LANDSAT and CIMEL

    NASA Technical Reports Server (NTRS)

    Kaufman, Y. J.; Tanre, D.; Karnieli, A.; Remer, L.; Holben, B.

    1999-01-01

    Spectral remote observations of dust properties from space and from the ground create a powerful tool for determination of dust absorption of solar radiation with an unprecedented accuracy. Absorption is a key component in understanding dust impact on climate. We use Landsat space-borne measurements at 0.47 to 2.2 micrometer over Senegal with ground-based sunphotometers to find that Saharan dust absorption of solar radiation is two to four times smaller than in models. Though dust absorbs in the blue, almost no absorption was found for wavelengths greater than 0.6 micrometer. The new finding increases by 50% recent estimated solar radiative forcing by dust and decreases the estimated dust heating of the lower troposphere. Dust transported from Asia shows slightly higher absorption probably due to the presence of black carbon from populated regions. Large-scale application of this method to satellite data from the Earth Observing System can reduce significantly the uncertainty in the dust radiative effects.

  3. 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.

  4. Improved determination of particulate absorption from combined filter pad and PSICAM measurements.

    PubMed

    Lefering, Ina; Röttgers, Rüdiger; Weeks, Rebecca; Connor, Derek; Utschig, Christian; Heymann, Kerstin; McKee, David

    2016-10-31

    Filter pad light absorption measurements are subject to two major sources of experimental uncertainty: the so-called pathlength amplification factor, β, and scattering offsets, o, for which previous null-correction approaches are limited by recent observations of non-zero absorption in the near infrared (NIR). A new filter pad absorption correction method is presented here which uses linear regression against point-source integrating cavity absorption meter (PSICAM) absorption data to simultaneously resolve both β and the scattering offset. The PSICAM has previously been shown to provide accurate absorption data, even in highly scattering waters. Comparisons of PSICAM and filter pad particulate absorption data reveal linear relationships that vary on a sample by sample basis. This regression approach provides significantly improved agreement with PSICAM data (3.2% RMS%E) than previously published filter pad absorption corrections. Results show that direct transmittance (T-method) filter pad absorption measurements perform effectively at the same level as more complex geometrical configurations based on integrating cavity measurements (IS-method and QFT-ICAM) because the linear regression correction compensates for the sensitivity to scattering errors in the T-method. This approach produces accurate filter pad particulate absorption data for wavelengths in the blue/UV and in the NIR where sensitivity issues with PSICAM measurements limit performance. The combination of the filter pad absorption and PSICAM is therefore recommended for generating full spectral, best quality particulate absorption data as it enables correction of multiple errors sources across both measurements.

  5. Picosecond absorption relaxation measured with nanosecond laser photoacoustics

    PubMed Central

    Danielli, Amos; Favazza, Christopher P.; Maslov, Konstantin; Wang, Lihong V.

    2010-01-01

    Picosecond absorption relaxation—central to many disciplines—is typically measured by ultrafast (femtosecond or picosecond) pump-probe techniques, which however are restricted to optically thin and weakly scattering materials or require artificial sample preparation. Here, we developed a reflection-mode relaxation photoacoustic microscope based on a nanosecond laser and measured picosecond absorption relaxation times. The relaxation times of oxygenated and deoxygenated hemoglobin molecules, both possessing extremely low fluorescence quantum yields, were measured at 576 nm. The added advantages in dispersion susceptibility, laser-wavelength availability, reflection sensing, and expense foster the study of natural—including strongly scattering and nonfluorescent—materials. PMID:21079726

  6. Picosecond absorption relaxation measured with nanosecond laser photoacoustics.

    PubMed

    Danielli, Amos; Favazza, Christopher P; Maslov, Konstantin; Wang, Lihong V

    2010-10-18

    Picosecond absorption relaxation-central to many disciplines-is typically measured by ultrafast (femtosecond or picosecond) pump-probe techniques, which however are restricted to optically thin and weakly scattering materials or require artificial sample preparation. Here, we developed a reflection-mode relaxation photoacoustic microscope based on a nanosecond laser and measured picosecond absorption relaxation times. The relaxation times of oxygenated and deoxygenated hemoglobin molecules, both possessing extremely low fluorescence quantum yields, were measured at 576 nm. The added advantages in dispersion susceptibility, laser-wavelength availability, reflection sensing, and expense foster the study of natural-including strongly scattering and nonfluorescent-materials.

  7. Analytical Validation of Accelerator Mass Spectrometry for Pharmaceutical Development: the Measurement of Carbon-14 Isotope Ratio.

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

    Keck, B D; Ognibene, T; Vogel, J S

    2010-02-05

    Accelerator mass spectrometry (AMS) is an isotope based measurement technology that utilizes carbon-14 labeled compounds in the pharmaceutical development process to measure compounds at very low concentrations, empowers microdosing as an investigational tool, and extends the utility of {sup 14}C labeled compounds to dramatically lower levels. It is a form of isotope ratio mass spectrometry that can provide either measurements of total compound equivalents or, when coupled to separation technology such as chromatography, quantitation of specific compounds. The properties of AMS as a measurement technique are investigated here, and the parameters of method validation are shown. AMS, independent of anymore » separation technique to which it may be coupled, is shown to be accurate, linear, precise, and robust. As the sensitivity and universality of AMS is constantly being explored and expanded, this work underpins many areas of pharmaceutical development including drug metabolism as well as absorption, distribution and excretion of pharmaceutical compounds as a fundamental step in drug development. The validation parameters for pharmaceutical analyses were examined for the accelerator mass spectrometry measurement of {sup 14}C/C ratio, independent of chemical separation procedures. The isotope ratio measurement was specific (owing to the {sup 14}C label), stable across samples storage conditions for at least one year, linear over 4 orders of magnitude with an analytical range from one tenth Modern to at least 2000 Modern (instrument specific). Further, accuracy was excellent between 1 and 3 percent while precision expressed as coefficient of variation is between 1 and 6% determined primarily by radiocarbon content and the time spent analyzing a sample. Sensitivity, expressed as LOD and LLOQ was 1 and 10 attomoles of carbon-14 (which can be expressed as compound equivalents) and for a typical small molecule labeled at 10% incorporated with {sup 14}C corresponds to 30

  8. Differential absorption lidar measurements of atmospheric temperature and pressure profiles

    NASA Technical Reports Server (NTRS)

    Korb, C. L.

    1981-01-01

    The theory and methodology of using differential absorption lidar techniques for the remote measurement of atmospheric pressure profiles, surface pressure, and temperature profiles from ground, air, and space-based platforms are presented. Pressure measurements are effected by means of high resolution measurement of absorption at the edges of the oxygen A band lines where absorption is pressure dependent due to collisional line broadening. Temperature is assessed using measurements of the absorption at the center of the oxygen A band line originating from a quantum state with high ground state energy. The population of the state is temperature dependent, allowing determination of the temperature through the Boltzmann term. The results of simulations of the techniques using Voigt profile and variational analysis are reported for ground-based, airborne, and Shuttle-based systems. Accuracies in the 0.5-1.0 K and 0.1-0.3% range are projected.

  9. 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.

  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. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. High sensitivity background absorption measurements in semiconductors

    NASA Astrophysics Data System (ADS)

    Giannini, Nathan; Silva, Junior R.; Wang, Chengao; Albrecht, Alexander R.; Melgaard, Seth D.; Sheik-Bahae, Mansoor

    2015-03-01

    Laser cooling in InGaP|GaAs double heterostructures (DHS) has been a sought after goal. Even though very high external quantum efficiency (EQE) has been achieved, background absorption has remained a bottleneck in achieving net cooling. The purpose of this study is to gain more insight into the source of the background absorption for InGaP|GaAs DHS as well as GaAs|AlGaAs DBRs by employing an excite-probe thermal Z-scan measurement.

  17. 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.

  18. 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.

  19. Advances in Methane Isotope Measurements via Direct Absorption Spectroscopy with Applications to Oil and Gas Source Characterization

    NASA Astrophysics Data System (ADS)

    Yacovitch, T. I.; Herndon, S. C.; Roscioli, J. R.; Petron, G.; Shorter, J. H.; Jervis, D.; McManus, J. B.; Nelson, D. D.; Zahniser, M. S.; Kolb, C. E., Jr.

    2015-12-01

    Instrumental developments in the measurement of multiple isotopes of methane (12CH4, 13CH4 and 12CH3D) are presented. A first generation 8-micron instrument quantifies 12CH4 and 13CH4 at a 1-second rate via tunable infrared direct absorption spectroscopy (TILDAS). A second generation instrument uses two 3-micron intraband cascade lasers in an Aerodyne dual laser chassis for simultaneous measurement of 12CH4, 13CH4 and 12CH3D. Sensitivity and noise performance improvements are examined. The isotopic signature of methane provides valuable information for emission source identification of this greenhouse gas. A first generation spectrometer has been deployed in the field on a mobile laboratory along with a sophisticated 4-tank calibration system. Calibrations are done on an agressive schedule, allowing for the correction of measured isotope ratios to an absolute isotope scale. Distinct isotopic signatures are found for a number of emission sources in the Denver-Julesburg Basin: oil and gas gathering stations, compressor stations and processing plants; a municipal landfill, and dairy/cattle operations. The isotopic signatures are compared with measured ethane/methane ratios. These direct absorption measurements have larger uncertainties than samples measured via gas chromatography-mass spectrometry, but have several advantages over canister sampling methods: individual sources of short duration are easier to isolate; calibrated isotope ratio results are available immediately; replicate measurements on a single source are easily performed; and the number of sources sampled is not limited by canister availability and processing time.

  20. Measurement of the absorption coefficient using the sound-intensity technique

    NASA Technical Reports Server (NTRS)

    Atwal, M.; Bernhard, R.

    1984-01-01

    The possibility of using the sound intensity technique to measure the absorption coefficient of a material is investigated. This technique measures the absorption coefficient by measuring the intensity incident on the sample and the net intensity reflected by the sample. Results obtained by this technique are compared with the standard techniques of measuring the change in the reverberation time and the standing wave ratio in a tube, thereby, calculating the random incident and the normal incident adsorption coefficient.

  1. Laser-based measurements of δ13 C and δ2 H methane isotope signatures: precisions competitive with mass spectrometry methods

    NASA Astrophysics Data System (ADS)

    Yacovitch, Tara; Shorter, Joanne; Nelson, David; Herndon, Scott; Agnese, Mike; McManus, Barry; Zahniser, Mark

    2017-04-01

    In order to understand how and why methane (CH4 ) concentrations change over time, it is necessary to understand their sources and sinks. Stable isotope measurements of 13 CH4 :12 CH4 and CH3 D:12 CH4 ratios constrain the inventory of these sinks and sources. Current measurements often depend on Isotope Ratio Mass Spectrometry (IRMS), which requires extensive sample preparation including cryogenic separation of methane from air and subsequent conversion to either CO2 or H2 . Here, we detail improvements to a direct-absorption laser spectrometer that enable fast and precise measurements of methane isotope ratios (δ13 C and δ2 H ) of ambient air samples, without such sample preparation. The measurement system consists of a laser-based direct absorption spectrometer configured with a sample manifold for measurement of discrete samples (as opposed to flow-through measurements). Samples are trapped in the instrument using a rapid sample switching technique that compares each flask sample against a monitor tank sample. This approach reduces instrument drift and results in excellent precision. Precisions of 0.054 o/oo for δ13 C and 1.4 o/oo for δ2 H have been achieved (Allan-Werle deviations). These results are obtained in 20 minutes using 4 replicate comparisons to a monitor tank.

  2. Continuous and unattended measurements of the site preference of nitrous oxide emitted from an agricultural soil using quantum cascade laser spectrometry with intercomparison with isotope ratio mass spectrometry.

    PubMed

    Yamamoto, Akinori; Uchida, Yoshitaka; Akiyama, Hiroko; Nakajima, Yasuhiro

    2014-07-15

    The difference between the (15)N natural abundance of (14)N-(15)N-O and (15)N-(14)N-O (site preference; SP) is used to understand the mechanisms underlying N2O emissions from soils. We investigated the use of quantum cascade laser (QCL) absorption spectrometry for continuous and precise analysis of the SP of N2O emitted from a field soil at atmospheric mixing ratios. A QCL-based spectrometer was used to determine the SP of soil-emitted N2O accumulated in a closed chamber system without preconcentration. N2O standards (<2500 ppbv) were used to evaluate the precision of the QCL spectrometry (QCLS) system. CO2 and H2O were removed from the gas samples. Intercomparison measurements of QCLS and isotope ratio mass spectrometry (IRMS) were performed on N2O calibration gases at different mixing ratios. The observed dependency of the QCLS result on the N2O mixing ratio was corrected. Measurement of SP of N2O emitted from the field suggested that the SP of N2O varied from 0 to 40‰ over a period of 1 month. The precisions of the SP measurements (300-2500 ppbv) were <1.9‰ for δ(15)N(α) values, <2.6‰ for δ(15)N(β) values, <2.1‰ for δ(15)N(bulk) values, and <2.1‰ for the SP (1 min averaging time) obtained on a once-an-hour calibrated QCLS system, with a cell temperature control precision of ±0.01 K. Continuous and unattended measurements of the SP of N2O emitted from soils were achieved at low N2O mixing ratios. The accuracy of the QCLS measurements for the SP of N2O was significantly improved by precisely controlling the temperature of the system and by correcting for the concentration dependency of the raw data through an intercomparison with IRMS measurements. Copyright © 2014 John Wiley & Sons, Ltd.

  3. 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.

  4. Microwave Resonator Measurements of Atmospheric Absorption Coefficients: A Preliminary Design Study

    NASA Technical Reports Server (NTRS)

    Walter, Steven J.; Spilker, Thomas R.

    1995-01-01

    A preliminary design study examined the feasibility of using microwave resonator measurements to improve the accuracy of atmospheric absorption coefficients and refractivity between 18 and 35 GHz. Increased accuracies would improve the capability of water vapor radiometers to correct for radio signal delays caused by Earth's atmosphere. Calibration of delays incurred by radio signals traversing the atmosphere has applications to both deep space tracking and planetary radio science experiments. Currently, the Cassini gravity wave search requires 0.8-1.0% absorption coefficient accuracy. This study examined current atmospheric absorption models and estimated that current model accuracy ranges from 5% to 7%. The refractivity of water vapor is known to 1% accuracy, while the refractivity of many dry gases (oxygen, nitrogen, etc.) are known to better than 0.1%. Improvements to the current generation of models will require that both the functional form and absolute absorption of the water vapor spectrum be calibrated and validated. Several laboratory techniques for measuring atmospheric absorption and refractivity were investigated, including absorption cells, single and multimode rectangular cavity resonators, and Fabry-Perot resonators. Semi-confocal Fabry-Perot resonators were shown to provide the most cost-effective and accurate method of measuring atmospheric gas refractivity. The need for accurate environmental measurement and control was also addressed. A preliminary design for the environmental control and measurement system was developed to aid in identifying significant design issues. The analysis indicated that overall measurement accuracy will be limited by measurement errors and imprecise control of the gas sample's thermodynamic state, thermal expansion and vibration- induced deformation of the resonator structure, and electronic measurement error. The central problem is to identify systematic errors because random errors can be reduced by averaging

  5. Food Iron Absorption Measured by an Extrinsic Tag

    PubMed Central

    Cook, J. D.; Layrisse, M.; Martinez-Torres, C.; Walker, R.; Monsen, E.; Finch, C. A.

    1972-01-01

    The paper describes the use of an extrinsic tag of inorganic radioiron to determine the total absorption of nonheme iron from a complete meal. The method was developed by measuring the iron absorbed from vegetable foods containing biosynthetically incorporated 55Fe (intrinsic tag) and from 59Fe added as a small dose of inorganic iron to the same meal (extrinsic tag). In studies with maize, black bean, and wheat, a consistent extrinsic: intrinsic radioiron absorption ratio averaging 1.10 was observed. Similar results were obtained with either ferrous or ferric iron as the extrinsic tag, and with doses of the latter ranging from 0.001 to 0.5 mg iron added to a test meal containing 2-4 mg of food iron. Adding the radioiron at different stages in preparation of the test meal also had little effect. Separate administration of the extrinsic tag was less satisfactory when small portions of a single food were employed, but with a complete meal, the separate dose was preferable. The extrinsic tag provided a valid measure of absorption despite marked differences in the iron status of the subject, and with wide changes in absorption imposed by adding desferrioxamine or ascorbic acid to the test meal. These findings indicate that there is a common pool of nonheme iron, the absorption of which is influenced by various blocking or enhancing substances present in the meal. PMID:5062612

  6. Pseudopotential calculations and photothermal lensing measurements of two-photon absorption in solids

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

    White, W.T. III

    1985-11-04

    We have studied two-photon absorption in solids theoretically and experimentally. We have shown that it is possible to use accurate band structure techniques to compute two-photon absorption spectra within 15% of measured values in a wide band-gap material, ZnS. The empirical pseudopotential technique that we used is significantly more accurate than previous models of two-photon absorption in zinc blende materials, including present tunneling theories (which are essentially parabolic-band results in disguise) and the nonparabolic-band formalism of Pidgeon et al. and Weiler. The agreement between our predictions and previous measurements allowed us to use ZnS as a reference material in ordermore » to validate a technique for measuring two-photon absorption that was previously untried in solids, pulsed dual-beam thermal lensing. With the validated technique, we examined nonlinear absorption in one other crystal (rutile) and in several glasses, including silicates, borosilicates, and one phosphate glass. Initially, we believed that the absorption edges of all the materials were comparable; however, subsequent evidence suggested that the effective band-gap energies of the glasses were above the energy of two photons in our measurement. Therefore, we attribute the nonlinear absorption that we observed in glasses to impurities or defects. The measured nonlinear absorption coefficients were of the order of a few cm/TW in the glasses and of the order of 10 cm/GW in the crystals, four orders of magnitude higher than in glasses. 292 refs.« less

  7. 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.

  8. 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%.

  9. [Gas Concentration Measurement Based on the Integral Value of Absorptance Spectrum].

    PubMed

    Liu, Hui-jun; Tao, Shao-hua; Yang, Bing-chu; Deng, Hong-gui

    2015-12-01

    The absorptance spectrum of a gas is the basis for the qualitative and quantitative analysis of the gas by the law of the Lambert-Beer. The integral value of the absorptance spectrum is an important parameter to describe the characteristics of the gas absorption. Based on the measured absorptance spectrum of a gas, we collected the required data from the database of HIT-RAN, and chose one of the spectral lines and calculated the integral value of the absorptance spectrum in the frequency domain, and then substituted the integral value into Lambert-Beer's law to obtain the concentration of the detected gas. By calculating the integral value of the absorptance spectrum we can avoid the more complicated calculation of the spectral line function and a series of standard gases for calibration, so the gas concentration measurement will be simpler and faster. We studied the changing trends of the integral values of the absorptance spectrums versus temperature. Since temperature variation would cause the corresponding variation in pressure, we studied the changing trends of the integral values of the absorptance spectrums versus both the pressure not changed with temperature and changed with the temperature variation. Based on the two cases, we found that the integral values of the absorptance spectrums both would firstly increase, then decrease, and finally stabilize with temperature increasing, but the ranges of specific changing trend were different in the two cases. In the experiments, we found that the relative errors of the integrated values of the absorptance spectrum were much higher than 1% and still increased with temperature when we only considered the change of temperature and completely ignored the pressure affected by the temperature variation, and the relative errors of the integrated values of the absorptance spectrum were almost constant at about only 1% when we considered that the pressure were affected by the temperature variation. As the integral value

  10. Multi-wavelength differential absorption measurements of chemical species

    NASA Astrophysics Data System (ADS)

    Brown, David M.

    The probability of accurate detection and quantification of airborne species is enhanced when several optical wavelengths are used to measure the differential absorption of molecular spectral features. Characterization of minor atmospheric constituents, biological hazards, and chemical plumes containing multiple species is difficult when using current approaches because of weak signatures and the use of a limited number of wavelengths used for identification. Current broadband systems such as Differential Optical Absorption Spectroscopy (DOAS) have either limitations for long-range propagation, or require transmitter power levels that are unsafe for operation in urban environments. Passive hyperspectral imaging systems that utilize absorption of solar scatter at visible and infrared wavelengths, or use absorption of background thermal emission, have been employed routinely for detection of airborne chemical species. Passive approaches have operational limitations at various ranges, or under adverse atmospheric conditions because the source intensity and spectrum is often an unknown variable. The work presented here describes a measurement approach that uses a known source of a low transmitted power level for an active system, while retaining the benefits of broadband and extremely long-path absorption operations. An optimized passive imaging system also is described that operates in the 3 to 4 mum window of the mid-infrared. Such active and passive instruments can be configured to optimize the detection of several hydrocarbon gases, as well as many other species of interest. Measurements have provided the incentive to develop algorithms for the calculations of atmospheric species concentrations using multiple wavelengths. These algorithms are used to prepare simulations and make comparisons with experimental results from absorption data of a supercontinuum laser source. The MODTRAN model is used in preparing the simulations, and also in developing additional

  11. 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.

  12. 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.

  13. Pulsed Airborne Lidar Measurements of C02 Column Absorption

    NASA Technical Reports Server (NTRS)

    Abshire, James B.; Riris, Haris; Allan, Graham R.; Weaver, Clark J.; Mao, Jianping; Sun, Xiaoli; Hasselbrack, William E.; Rodriquez, Michael; Browell, Edward V.

    2011-01-01

    We report on airborne lidar measurements of atmospheric CO2 column density for an approach being developed as a candidate for NASA's ASCENDS mission. It uses a pulsed dual-wavelength lidar measurement based on the integrated path differential absorption (IPDA) technique. We demonstrated the approach using the CO2 measurement from aircraft in July and August 2009 over four locations. The results show clear CO2 line shape and absorption signals, which follow the expected changes with aircraft altitude from 3 to 13 km. The 2009 measurements have been analyzed in detail and the results show approx.1 ppm random errors for 8-10 km altitudes and approx.30 sec averaging times. Airborne measurements were also made in 2010 with stronger signals and initial analysis shows approx. 0.3 ppm random errors for 80 sec averaging times for measurements at altitudes> 6 km.

  14. 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.

  15. 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.

  16. 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.

  17. Measurement of Absorption Coefficient of Paraformaldehyde and Metaldehyde with Terahertz Spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Xia, T.; Chen, Q.; Sun, Q.; Deng, Y.; Wang, C.

    2018-03-01

    The characteristic absorption spectra of paraformaldehyde and metaldehyde in the terahertz frequency region are obtained by terahertz time-domain spectroscopy (THz-TDS). In order to reduce the absorption of terahertz (THz) wave by water vapor in the air and the background noise, the measurement system was filled with dry air and the measurements were conducted at the temperature of 24°C. Meanwhile, the humidity was controlled within 10% RH. The THz frequency domain spectra of samples and their references from 0 to 2.5 THz were analyzed via Fourier transform. The refractive index and absorption coefficients of the two aldehydes were calculated by the model formulas. From 0.1 to 2.5 THz, there appear two weak absorption peaks at 1.20 and 1.66 THz in the absorption spectra of paraformaldehyde. Only one distinct absorption peak emerges at 1.83 THz for metaldehyde. There are significant differences between the terahertz absorption coefficients of paraformaldehyde and metaldehyde, which can be used as "fingerprints" to identify these substances. Furthermore, the relationship between the average absorption coefficients and mass concentrations was investigated and the average absorption coefficient-mass concentration diagrams of paraformaldehyde and metaldehyde were shown. For paraformaldehyde, there is a linear relationship between the average absorption coefficient and the natural logarithm of mass concentration. For metaldehyde, there exists a simpler linear relationship between the average absorption coefficient and the mass concentration. Because of the characteristics of THz absorption of paraformaldehyde and metaldehyde, the THz-TDS can be applied to the qualitative and quantitative detection of the two aldehydes to reduce the unpredictable hazards due to these substances.

  18. Determining the Uncertainty of X-Ray Absorption Measurements

    PubMed Central

    Wojcik, Gary S.

    2004-01-01

    X-ray absorption (or more properly, x-ray attenuation) techniques have been applied to study the moisture movement in and moisture content of materials like cement paste, mortar, and wood. An increase in the number of x-ray counts with time at a location in a specimen may indicate a decrease in moisture content. The uncertainty of measurements from an x-ray absorption system, which must be known to properly interpret the data, is often assumed to be the square root of the number of counts, as in a Poisson process. No detailed studies have heretofore been conducted to determine the uncertainty of x-ray absorption measurements or the effect of averaging data on the uncertainty. In this study, the Poisson estimate was found to adequately approximate normalized root mean square errors (a measure of uncertainty) of counts for point measurements and profile measurements of water specimens. The Poisson estimate, however, was not reliable in approximating the magnitude of the uncertainty when averaging data from paste and mortar specimens. Changes in uncertainty from differing averaging procedures were well-approximated by a Poisson process. The normalized root mean square errors decreased when the x-ray source intensity, integration time, collimator size, and number of scanning repetitions increased. Uncertainties in mean paste and mortar count profiles were kept below 2 % by averaging vertical profiles at horizontal spacings of 1 mm or larger with counts per point above 4000. Maximum normalized root mean square errors did not exceed 10 % in any of the tests conducted. PMID:27366627

  19. 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.

  20. 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

  1. 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.

  2. 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

  3. [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.

  4. 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.

  5. 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.

  6. 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.

  7. Towards higher stability of resonant absorption measurements in pulsed plasmas.

    PubMed

    Britun, Nikolay; Michiels, Matthieu; Snyders, Rony

    2015-12-01

    Possible ways to increase the reliability of time-resolved particle density measurements in pulsed gaseous discharges using resonant absorption spectroscopy are proposed. A special synchronization, called "dynamic source triggering," between a gated detector and two pulsed discharges, one representing the discharge of interest and another being used as a reference source, is developed. An internal digital delay generator in the intensified charge coupled device camera, used at the same time as a detector, is utilized for this purpose. According to the proposed scheme, the light pulses from the reference source follow the gates of detector, passing through the discharge of interest only when necessary. This allows for the utilization of short-pulse plasmas as reference sources, which is critical for time-resolved absorption analysis of strongly emitting pulsed discharges. In addition to dynamic source triggering, the reliability of absorption measurements can be further increased using simultaneous detection of spectra relevant for absorption method, which is also demonstrated in this work. The proposed methods are illustrated by the time-resolved measurements of the metal atom density in a high-power impulse magnetron sputtering (HiPIMS) discharge, using either a hollow cathode lamp or another HiPIMS discharge as a pulsed reference source.

  8. Vacuum Ultraviolet Absorption Measurements of Atomic Oxygen in a Shock Tube

    NASA Technical Reports Server (NTRS)

    Meyer, Scott Andrew

    1995-01-01

    The absorption of vacuum ultraviolet light by atomic oxygen has been measured in the Electric Arc-driven Shock Tube (EAST) Facility at NASA-Ames Research Center. This investigation demonstrates the instrumentation required to determine atomic oxygen concentrations from absorption measurements in impulse facilities. A shock wave dissociates molecular oxygen, producing a high temperature sample of atomic oxygen in the shock tube. A probe beam is generated with a Raman-shifted ArF excimer laser. By suitable tuning of the laser, absorption is measured over a range of wavelengths in the region of the atomic line at 130.49 nm. The line shape function is determined from measurements at atomic oxygen densities of 3 x 10(exp 17) and 9 x 10(exp 17)/cu cm. The broadening coefficient for resonance interactions is deduced from this data, and this value is in accord with available theoretical models.

  9. Vacuum Ultraviolet Absorption Measurements of Atomic Oxygen in a Shock Tube

    NASA Technical Reports Server (NTRS)

    Meyer, Scott Andrew

    1995-01-01

    The absorption of vacuum ultraviolet light by atomic oxygen has been measured in the Electric Arc-driven Shock Tube (EAST) Facility at NASA-Ames Research Center. This investigation demonstrates the instrumentation required to determine atomic oxygen concentrations from absorption measurements in impulse facilities. A shock wave dissociates molecular oxygen, producing a high temperature sample of atomic oxygen in the shock tube. A probe beam is generated with a Raman-shifted ArF excimer laser. By suitable tuning of the laser, absorption is measured over a range of wavelengths in the region of the atomic line at 130.49 nm. The line shape function is determined from measurements at atomic oxygen densities of 3x10(exp 17) and 9x10(exp 17) cm(exp -3). The broadening coefficient for resonance interactions is deduced from this data, and this value is in accord with available theoretical models.

  10. Vacuum Ultraviolet Absorption Measurements of Atomic Oxygen in a Shock Tube

    NASA Technical Reports Server (NTRS)

    Meyer, Scott Andrew

    1995-01-01

    The absorption of vacuum ultraviolet light by atomic oxygen has been measured in the Electric Arc-driven Shock Tube (EAST) Facility at NASA-Ames Research Center. This investigation demonstrates the instrumentation required to determine atomic oxygen concentrations from absorption measurements in impulse facilities. A shock wave dissociates molecular oxygen, producing a high temperature sample of atomic oxygen in the shock tube. A probe beam is generated with a Raman-shifted ArF excimer laser. By suitable tuning of the laser, absorption is measured over a range of wavelengths in the region of the atomic line at 130.49 nm. The line shape function is determined from measurements at atomic oxygen densities of 3 x 10(exp 17) and 9 x 10(exp 17) cm(exp -3). The broadening coefficient for resonance interactions is deduced from this data, and this value is in accord with available theoretical models.

  11. Accelerator mass spectrometry for measurement of long-lived radioisotopes.

    PubMed

    Elmore, D; Phillips, F M

    1987-05-01

    Particle accelerators, such as those built for research in nuclear physics, can also be used together with magnetic and electrostatic mass analyzers to measure rare isotopes at very low abundance ratios. All molecular ions can be eliminated when accelerated to energies of millions of electron volts. Some atomic isobars can be eliminated with the use of negative ions; others can be separated at high energies by measuring their rate of energy loss in a detector. The long-lived radioisotopes (10)Be, (14)C,(26)A1, 36Cl, and (129)1 can now be measured in small natural samples having isotopic abundances in the range 10(-12) to 10(- 5) and as few as 10(5) atoms. In the past few years, research applications of accelerator mass spectrometry have been concentrated in the earth sciences (climatology, cosmochemistry, environmental chemistry, geochronology, glaciology, hydrology, igneous petrogenesis, minerals exploration, sedimentology, and volcanology), in anthropology and archeology (radiocarbon dating), and in physics (searches for exotic particles and measurement of halflives). In addition, accelerator mass spectrometry may become an important tool for the materials and biological sciences.

  12. Accelerator Mass Spectrometry for Measurement of Long-Lived Radioisotopes

    NASA Astrophysics Data System (ADS)

    Elmore, David; Phillips, Fred M.

    1987-05-01

    Particle accelerators, such as those built for research in nuclear physics, can also be used together with magnetic and electrostatic mass analyzers to measure rare isotopes at very low abundance ratios. All molecular ions can be eliminated when accelerated to energies of millions of electron volts. Some atomic isobars can be eliminated with the use of negative ions; others can be separated at high energies by measuring their rate of energy loss in a detector. The long-lived radioisotopes 10Be, 14C, 26Al, 36Cl, and 129I can now be measured in small natural samples having isotopic abundances in the range 10-12 to 10-15 and as few as 105 atoms. In the past few years, research applications of accelerator mass spectrometry have been concentrated in the earth sciences (climatology, cosmochemistry, environmental chemistry, geochronology, glaciology, hydrology, igneous petrogenesis, minerals exploration, sedimentology, and volcanology), in anthropology and archeology (radiocarbon dating), and in physics (searches for exotic particles and measurement of half-lives). In addition, accelerator mass spectrometry may become an important tool for the materials and biological sciences.

  13. Direct measurements of nonlinear absorption and refraction in solutions of phthalocyanines

    NASA Technical Reports Server (NTRS)

    Wei, T. H.; Hagan, D. J.; Sence, M. J.; Van Stryland, E. W.; Perry, J. W.; Coulter, D. R.

    1992-01-01

    Direct measurements are reported of the excited singlet-state absorption cross section and the associated nonlinear refractive cross section using picosecond pulses at 532 nm in solutions of phthalocyanine and naphthalocyanine dyes. By monitoring the transmittance and far-field spatial beam distortion for different pulsewidths in the picosecond regime, it is shown that both the nonlinear absorption and refraction are fluence (energy-per-unit-area) rather than irradiance dependent. Thus, excited-state absorption is the dominant nonlinear absorption process, and the observed nonlinear refraction is also due to real population excitation.

  14. Noninvasive photoacoustic measurement of absorption coefficient using internal light irradiation of cylindrical diffusing fiber

    NASA Astrophysics Data System (ADS)

    Peng, Dong-qing; Zhu, Li-li; Li, Zhi-fang; Li, Hui

    2017-09-01

    Absorption coefficient of biological tissue is an important parameter in biomedicine, but its determination remains a challenge. In this paper, we propose a method using focusing photoacoustic imaging technique and internal light irradiation of cylindrical diffusing fiber (CDF) to quantify the target optical absorption coefficient. Absorption coefficients for ink absorbers are firstly determined through photoacoustic and spectrophotometric measurements at the same excitation, which demonstrates the feasibility of this method. Also, the optical absorption coefficients of ink absorbers with several concentrations are measured. Finally, the two-dimensional scanning photoacoustic image is obtained. Optical absorption coefficient measurement and simultaneous photoacoustic imaging of absorber non-invasively are the typical characteristics of the method. This method can play a significant role for non-invasive determination of blood oxygen saturation, the absorption-based imaging and therapy.

  15. Integrating ion mobility spectrometry into mass spectrometry-based exposome measurements: what can it add and how far can it go?

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

    Metz, Thomas O.; Baker, Erin S.; Schymanski, Emma L.

    Here, measuring the exposome remains a challenge due to the range and number of anthropogenic molecules that are encountered in our daily lives, as well as the complex systemic responses to these exposures. One option for improving the coverage, dynamic range and throughput of measurements is to incorporate ion mobility spectrometry (IMS) into current mass spectrometry (MS)-based analytical methods. In this perspective, we briefly review the state-of-the-art in measuring the exposome, and discuss the potential use for IMS-MS and the physico-chemical property of collisional cross section in both exposure assessment and molecular identification.

  16. Integrating ion mobility spectrometry into mass spectrometry-based exposome measurements: what can it add and how far can it go?

    DOE PAGES

    Metz, Thomas O.; Baker, Erin S.; Schymanski, Emma L.; ...

    2016-12-06

    Here, measuring the exposome remains a challenge due to the range and number of anthropogenic molecules that are encountered in our daily lives, as well as the complex systemic responses to these exposures. One option for improving the coverage, dynamic range and throughput of measurements is to incorporate ion mobility spectrometry (IMS) into current mass spectrometry (MS)-based analytical methods. In this perspective, we briefly review the state-of-the-art in measuring the exposome, and discuss the potential use for IMS-MS and the physico-chemical property of collisional cross section in both exposure assessment and molecular identification.

  17. 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.

  18. 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.

  19. 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.

  20. Measurement of temperature profiles in flames by emission-absorption spectroscopy

    NASA Technical Reports Server (NTRS)

    Simmons, F. S.; Arnold, C. B.; Lindquist, G. H.

    1972-01-01

    An investigation was conducted to explore the use of infrared and ultraviolet emission-absorption spectroscopy for determination of temperature profiles in flames. Spectral radiances and absorptances were measured in the 2.7-micron H2O band and the 3064-A OH band in H2/O2 flames for several temperature profiles which were directly measured by a sodium line-reversal technique. The temperature profiles, determined by inversion of the infrared and ultraviolet spectra, showed an average disagreement with line-reversal measurements of 50 K for the infrared and 200 K for the ultraviolet at a temperature of 2600 K. The reasons for these discrepancies are discussed in some detail.

  1. X-Ray Absorption Measured in the Resonant Auger Scattering Mode

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

    Hikosaka, Y.; Shigemasa, E.; Kaneyasu, T.

    2008-08-15

    We report both experimental and theoretical studies on x-ray absorption measured in the resonant Auger scattering mode of gas phase carbon monoxide near the O1s{yields}2{pi} region. Both experiment and theory display a crucial difference between the x-ray absorption profiles obtained in the conventional and resonant scattering modes. Lifetime vibrational interference is the main source of the difference. It is demonstrated that such interference, which arises from a coherent excitation to overlapping intermediate levels, ruins the idea for obtaining x-ray absorption spectra in a lifetime broadening free regime.

  2. Uncertainty budgets for liquid waveguide CDOM absorption measurements.

    PubMed

    Lefering, Ina; Röttgers, Rüdiger; Utschig, Christian; McKee, David

    2017-08-01

    Long path length liquid waveguide capillary cell (LWCC) systems using simple spectrometers to determine the spectral absorption by colored dissolved organic matter (CDOM) have previously been shown to have better measurement sensitivity compared to high-end spectrophotometers using 10 cm cuvettes. Information on the magnitude of measurement uncertainties for LWCC systems, however, has remained scarce. Cross-comparison of three different LWCC systems with three different path lengths (50, 100, and 250 cm) and two different cladding materials enabled quantification of measurement precision and accuracy, revealing strong wavelength dependency in both parameters. Stable pumping of the sample through the capillary cell was found to improve measurement precision over measurements made with the sample kept stationary. Results from the 50 and 100 cm LWCC systems, with higher refractive index cladding, showed systematic artifacts including small but unphysical negative offsets and high-frequency spectral perturbations due to limited performance of the salinity correction. In comparison, the newer 250 cm LWCC with lower refractive index cladding returned small positive offsets that may be physically correct. After null correction of measurements at 700 nm, overall agreement of CDOM absorption data at 440 nm was found to be within 5% root mean square percentage error.

  3. 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

  4. Resonance Ionization Mass Spectrometry System for Measurement of Environmental Samples

    NASA Astrophysics Data System (ADS)

    Pibida, L.; McMahon, C. A.; Nörtershäuser, W.; Bushaw, B. A.

    2002-10-01

    A resonance ionization mass spectrometry (RIMS) system has been developed at the National Institute of Standards and Technology (NIST) for sensitive and selective determination of radio-cesium in the environment. The overall efficiency was determined to be 4×10-7 with a combined (laser and mass spectrometer) selectivity of 108 for both 135Cs and 137Cs with respect to 133Cs. RIMS isotopic ratio measurements of 135Cs/ 137Cs were performed on a nuclear fuel burn-up sample and compared to measurements on a similar system at Pacific Northwest National Laboratory (PNNL) and to conventional thermal ionization mass spectrometry (TIMS). Results of preliminary RIMS investigations on a freshwater lake sediment sample are also discussed.

  5. Airborne Measurements of CO2 Column Absorption and Range Using a Pulsed Direct-Detection Integrated Path Differential Absorption Lidar

    NASA Technical Reports Server (NTRS)

    Abshire, James B.; Riris, Haris; Weaver, Clark J.; Mao, Jianping; Allan, Graham R.; Hasselbrack, William E.; Browell, Edward V.

    2013-01-01

    We report on airborne CO2 column absorption measurements made in 2009 with a pulsed direct-detection lidar operating at 1572.33 nm and utilizing the integrated path differential absorption technique. We demonstrated these at different altitudes from an aircraft in July and August in flights over four locations in the central and eastern United States. The results show clear CO2 line shape and absorption signals, which follow the expected changes with aircraft altitude from 3 to 13 km. The lidar measurement statistics were also calculated for each flight as a function of altitude. The optical depth varied nearly linearly with altitude, consistent with calculations based on atmospheric models. The scatter in the optical depth measurements varied with aircraft altitude as expected, and the median measurement precisions for the column varied from 0.9 to 1.2 ppm. The altitude range with the lowest scatter was 810 km, and the majority of measurements for the column within it had precisions between 0.2 and 0.9 ppm.

  6. Two-photon absorption measurements of deep UV transmissible materials at 213 nm

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

    Patankar, S.; Yang, S. T.; Moody, J. D.

    We report on two photon absorption measurements at 213nm of deep UV transmissible media including LiF, MgF 2, CaF 2, BaF 2, Sapphire (Al 2O 3) and high purity grades of fused-silica (SiO 2). A high stability 24ps Nd:YAG laser operating at the 5th harmonic (213nm) was used to generate a high intensity, long Rayleigh length Gaussian focus inside the samples. The measurements of the Fluoride crystals and Sapphire indicate two photon absorption coefficients between 0.004 and 0.82 cm/GW. We find that different grades of fused silica performed near identically for two photon absorption, however, there are differences in linearmore » losses associated with purity. A low two photon absorption cross section is measured for MgF 2 making it an ideal material for the propagation of high intensity deep UV lasers.« less

  7. Two-photon absorption measurements of deep UV transmissible materials at 213 nm

    DOE PAGES

    Patankar, S.; Yang, S. T.; Moody, J. D.; ...

    2017-09-19

    We report on two photon absorption measurements at 213nm of deep UV transmissible media including LiF, MgF 2, CaF 2, BaF 2, Sapphire (Al 2O 3) and high purity grades of fused-silica (SiO 2). A high stability 24ps Nd:YAG laser operating at the 5th harmonic (213nm) was used to generate a high intensity, long Rayleigh length Gaussian focus inside the samples. The measurements of the Fluoride crystals and Sapphire indicate two photon absorption coefficients between 0.004 and 0.82 cm/GW. We find that different grades of fused silica performed near identically for two photon absorption, however, there are differences in linearmore » losses associated with purity. A low two photon absorption cross section is measured for MgF 2 making it an ideal material for the propagation of high intensity deep UV lasers.« less

  8. Measurement of the aerosol absorption coefficient with the nonequilibrium process

    NASA Astrophysics Data System (ADS)

    Li, Liang; Li, Jingxuan; Bai, Hailong; Li, Baosheng; Liu, Shanlin; Zhang, Yang

    2018-02-01

    On the basis of the conventional Jamin interferometer,the improved measuring method is proposed that using a polarization type reentrant Jamin interferometer measures atmospheric aerosol absorption coefficient under the photothermal effect.The paper studies the relationship between the absorption coefficient of atmospheric aerosol particles and the refractive index change of the atmosphere.In Matlab environment, the variation curves of the output voltage of the interferometer with different concentration aerosol samples under stimulated laser irradiation were plotted.Besides, the paper also studies the relationship between aerosol concentration and the time required for the photothermal effect to reach equilibrium.When using the photothermal interferometry the results show that the time required for the photothermal effect to reach equilibrium is also increasing with the increasing concentration of aerosol particles,the absorption coefficient and time of aerosol in the process of nonequilibrium are exponentially changing.

  9. 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.

  10. 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.

  11. Agnostic stacking of intergalactic doublet absorption: measuring the Ne VIII population

    NASA Astrophysics Data System (ADS)

    Frank, Stephan; Pieri, Matthew M.; Mathur, Smita; Danforth, Charles W.; Shull, J. Michael

    2018-05-01

    We present a blind search for doublet intergalactic metal absorption with a method dubbed `agnostic stacking'. Using a forward-modelling framework, we combine this with direct detections in the literature to measure the overall metal population. We apply this novel approach to the search for Ne VIII absorption in a set of 26 high-quality COS spectra. We probe to an unprecedented low limit of log N>12.3 at 0.47≤z ≤1.34 over a path-length Δz = 7.36. This method selects apparent absorption without requiring knowledge of its source. Stacking this mixed population dilutes doublet features in composite spectra in a deterministic manner, allowing us to measure the proportion corresponding to Ne VIII absorption. We stack potential Ne VIII absorption in two regimes: absorption too weak to be significant in direct line studies (12.3 < log N < 13.7), and strong absorbers (log N > 13.7). We do not detect Ne VIII absorption in either regime. Combining our measurements with direct detections, we find that the Ne VIII population is reproduced with a power-law column density distribution function with slope β = -1.86 ^{+0.18 }_{ -0.26} and normalization log f_{13.7} = -13.99 ^{+0.20 }_{ -0.23}, leading to an incidence rate of strong Ne VIII absorbers dn/dz =1.38 ^{+0.97 }_{ -0.82}. We infer a cosmic mass density for Ne VIII gas with 12.3 < log N < 15.0 of Ω _{{{Ne {VIII}}}} = 2.2 ^{+1.6 }_{ _-1.2} × 10^{-8}, a value significantly lower that than predicted by recent simulations. We translate this density into an estimate of the baryon density Ωb ≈ 1.8 × 10-3, constituting 4 per cent of the total baryonic mass.

  12. Technical note: Aerosol light absorption measurements with a carbon analyser - Calibration and precision estimates

    NASA Astrophysics Data System (ADS)

    Ammerlaan, B. A. J.; Holzinger, R.; Jedynska, A. D.; Henzing, J. S.

    2017-09-01

    Equivalent Black Carbon (EBC) and Elemental Carbon (EC) are different mass metrics to quantify the amount of combustion aerosol. Both metrics have their own measurement technique. In state-of-the-art carbon analysers, optical measurements are used to correct for organic carbon that is not evolving because of pyrolysis. These optical measurements are sometimes used to apply the technique of absorption photometers. Here, we use the transmission measurements of our carbon analyser for simultaneous determination of the elemental carbon concentration and the absorption coefficient. We use MAAP data from the CESAR observatory, the Netherlands, to correct for aerosol-filter interactions by linking the attenuation coefficient from the carbon analyser to the absorption coefficient measured by the MAAP. Application of the calibration to an independent data set of MAAP and OC/EC observations for the same location shows that the calibration is applicable to other observation periods. Because of simultaneous measurements of light absorption properties of the aerosol and elemental carbon, variation in the mass absorption efficiency (MAE) can be studied. We further show that the absorption coefficients and MAE in this set-up are determined within a precision of 10% and 12%, respectively. The precisions could be improved to 4% and 8% when the light transmission signal in the carbon analyser is very stable.

  13. Measurements of near-IR water vapor absorption at high pressure and temperature

    NASA Astrophysics Data System (ADS)

    Rieker, G. B.; Liu, X.; Li, H.; Jeffries, J. B.; Hanson, R. K.

    2007-03-01

    Tunable diode lasers (TDLs) are used to measure high resolution (0.1 cm-1), near-infrared (NIR) water vapor absorption spectra at 700 K and pressures up to 30 atm within a high-pressure and -temperature optical cell in a high-uniformity tube furnace. Both direct absorption and wavelength modulation with second harmonic detection (WMS-2f) spectra are obtained for 6 cm-1 regions near 7204 cm-1 and 7435 cm-1. Direct absorption measurements at 700 K and 10 atm are compared with simulations using spectral parameters from HITRAN and a hybrid database combining HITRAN with measured spectral constants for transitions in the two target spectral regions. The hybrid database reduces RMS error between the simulation and the measurements by 45% for the 7204 cm-1 region and 28% for the 7435 cm-1 region. At pressures above 10 atm, the breakdown of the impact approximation inherent to the Lorentzian line shape model becomes apparent in the direct absorption spectra, and measured results are in agreement with model results and trends at elevated temperatures reported in the literature. The wavelength-modulation spectra are shown to be less affected by the breakdown of the impact approximation and measurements agree well with the hybrid database predictions to higher pressures (30 atm).

  14. Measuring high spectral resolution specific absorption coefficients for use with hyperspectral imagery

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

    Keller, M.; Bostater, C.

    1997-06-01

    A portable, long path length (50 cm), flow through, absorption tube system is utilized to obtain in-situ specific absorption coefficients from various water environments consisting of both clear and turbid water conditions from an underway ship or vessel. The high spectral resolution absorption signatures can be obtained and correlated with measured water quality parameters along a ship track. The long path cuvette system is capable of measuring important water quality parameters such as chlorophyll-a, seston or total suspended matter, tannins, humics, fulvic acids, or dissolved organic matter (dissolved organic carbon, DOC). The various concentrations of these substances can be determinedmore » and correlated with laboratory measurements using the double inflection ratio (DIR) of the spectra based upon derivative spectroscopy. The DIR is determined for all of the possible combinations of the bands ranging from 362-1115 nm using 252 channels, as described previously by Bostater. The information gathered from this system can be utilized in conjunction with hyperspectral imagery that allows one to relate reflectance and absorption to water quality of a particular environment. A comparison is made between absorption signatures and reflectance obtained from the Banana River, Florida.« less

  15. Multi-wavelength aerosol light absorption measurements in the Amazon rainforest

    NASA Astrophysics Data System (ADS)

    Saturno, Jorge; Chi, Xuguang; Pöhlker, Christopher; Morán, Daniel; Ditas, Florian; Massabò, Dario; Prati, Paolo; Rizzo, Luciana; Artaxo, Paulo; Andreae, Meinrat

    2015-04-01

    The most important light-absorbing aerosol is black carbon (BC), which is emitted by incomplete combustion of fossil fuels and biomass. BC is considered the second anthropogenic contributor to global warming. Beyond BC, other aerosols like some organics, dust, and primary biological aerosol particles are able to absorb radiation. In contrast to BC, the light absorption coefficient of these aerosols is wavelength dependent. Therefore, multi-wavelength measurements become important in environments where BC is not the predominant light-absorbing aerosol like in the Amazon. The Amazon Tall Tower Observatory (ATTO) site is located in the remote Amazon rainforest, one of the most pristine continental sites in the world during the wet season. In the dry season, winds coming from the southern hemisphere are loaded with biomass burning aerosol particles originated by farming-related deforestation. BC and aerosol number concentration data from the last two years indicate this is the most polluted period. Two different techniques have been implemented to measure the light absorption at different wavelengths; one of them is the 7-wavelengths Aethalometer, model AE30, an instrument that measures the light attenuation on a filter substrate and requires multiple scattering and filter-loading corrections to retrieve the light absorption coefficient. The other method is an offline technique, the Multi-Wavelength Absorbance Analysis (MWAA), which is able to measure reflectance and absorbance by aerosols collected on a filter and, by means of a radiative model, can retrieve the light absorption coefficient. Filters collected during May-September 2014, comprehending wet-to-dry transition and most of the dry season, were analyzed. The results indicate that the Absorption Ångström Exponent (AAE), a parameter that is directly proportional to the wavelength dependence of the aerosol light absorption, is close to 1.0 during the transition period and slightly decreases in the beginning of

  16. Tunable diode-laser absorption measurements of methane at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Nagali, V.; Chou, S. I.; Baer, D. S.; Hanson, R. K.; Segall, J.

    1996-07-01

    A diode-laser sensor system based on absorption spectroscopy techniques has been developed to monitor CH4 nonintrusively in high-temperature environments. Fundamental spectroscopic parameters, including the line strengths of the transitions in the R(6) manifold of the 2 nu 3 band near 1.646 mu m, have been determined from high-resolution absorption measurements in a heated static cell. In addition, a corrected expression for the CH 4 partition function has been validated experimentally over the temperature range from 400 to 915 K. Potential applications of the diode-laser sensor system include process control, combustion measurements, and atmospheric monitoring.

  17. Cryogenic Thermal Absorptance Measurements on Small-Diameter Stainless Steel Tubing

    NASA Technical Reports Server (NTRS)

    Tuttle, James; Jahromi, Amir; Canavan, Edgar; DiPirro, Michael

    2015-01-01

    The Mid Infrared Instrument (MIRI) on the James Webb Space Telescope includes a mechanical cryocooler which cools its detectors to their 6 Kelvin operating temperature. The coolant gas flows through several meters of small-diameter stainless steel tubing, which is exposed to thermal radiation from its environment. Over much of its length this tubing is gold-plated to minimize the absorption of this radiant heat. In order to confirm that the cryocooler will meet MIRI's requirements, the thermal absorptance of this tubing was measured as a function of its environment temperature. We describe the measurement technique and present the results.

  18. Method for measuring changes in light absorption of highly scattering media

    DOEpatents

    Bigio, Irving J.; Johnson, Tamara M.; Mourant, Judith R.

    2002-01-01

    The noninvasive measurement of variations in absorption that are due to changes in concentrations of biochemically relevant compounds in tissue is important in many clinical settings. One problem with such measurements is that the pathlength traveled by the collected light through the tissue depends on the scattering properties of the tissue. It is demonstrated, using both Monte Carlo simulations and experimental measurements, that for an appropriate separation between light-delivery and light-collection fibers, the pathlength of the collected photons is insensitive to scattering parameters for the range of parameters typically found in tissue. This is important for developing rapid, noninvasive, inexpensive, and accurate methods for measuring absorption changes in tissue.

  19. Shock tube measurements of the optical absorption of triatomic carbon, C3

    NASA Technical Reports Server (NTRS)

    Jones, J. J.

    1977-01-01

    The spectral absorption of C3 has been measured in a shock tube using a test gas mixture of acetylene diluted with argon. The absorption of a pulsed xenon light source was measured by means of eight photomultiplier channels to a spectrograph and an accompanying drum camera. The postshock test gas temperature and pressure were varied over the range 3300-4300 K and 0.36 to 2.13 atmospheres, respectively. The results showed appreciable absorption from C3 for the wavelength range 300 to 540 nanometers. The computed electronic oscillator strength varied from 0.12 to 0.06 as a function of temperature.

  20. [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.

  1. 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).

  2. The temperature measurement research for high-speed flow based on tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Di, Yue; Jin, Yi; Jiang, Hong-liang; Zhai, Chao

    2013-09-01

    Due to the particularity of the high-speed flow, in order to accurately obtain its' temperature, the measurement system should has some characteristics of not interfereing with the flow, non-contact measurement and high time resolution. The traditional measurement method cannot meet the above requirements, however the measurement method based on tunable diode laser absorption spectroscopy (TDLAS) technology can meet the requirements for high-speed flow temperature measurement. When the near-infared light of a specific frequency is through the media to be measured, it will be absorbed by the water vapor molecules and then the transmission light intensity is detected by the detector. The temperature of the water vapor which is also the high-speed flow temperature, can be accurately obtained by the Beer-Lambert law. This paper focused on the research of absorption spectrum method for high speed flow temperature measurement with the scope of 250K-500K. Firstly, spectral line selection method for low temperature measurement of high-speed flow is discussed. Selected absorption lines should be isolated and have a high peak absorption within the range of 250-500K, at the same time the interference of the other lines should be avoided, so that a high measurement accuracy can be obtained. According to the near-infrared absorption spectra characteristics of water vapor, four absorption lines at the near 1395 nm and 1409 nm are selected. Secondly, a system for the temperature measurement of the water vapor in the high-speed flow is established. Room temperature are measured through two methods, direct absorption spectroscopy (DAS) and wavelength modulation spectroscopy (WMS) ,the results show that this system can realize on-line measurement of the temperature and the measurement error is about 3%. Finally, the system will be used for temperature measurement of the high-speed flow in the shock tunnel, its feasibility of measurement is analyzed.

  3. Measurements of the absorption coefficient of stratospheric aerosols

    NASA Technical Reports Server (NTRS)

    Ogren, J. A.; Ahlquist, N. C.; Clarke, A. D.; Charlson, R. J.

    1981-01-01

    The absorption coefficients of stratospheric aerosols are measured using a variation on the integrating plate method. The technique is based on the decrease in the transparency of a substrate when an absorbing aerosol is deposited on it. A Lambert scatterer is placed behind the substrate to integrate forward scattered light and minimize the effect of scattering on the measurement. The low pressure in the stratosphere is used for the direct impaction of particles onto a narrow strip of opal glass. The eight samples collected had a median value of 4 x 10 to the -9th m with an uncertainty of + or - 5 x 10 to the -9th m. If this absorption is due to graphitic carbon, then its concentration is estimated at about 0.4 ng/cu m, or about 0.25% of the total aerosol mass concentration. Estimates of the aerosol scattering coefficients based on satellite extinction inversions result in an aerosol single-scattering albedo in the range of 0.96-1.0.

  4. 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.

  5. 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

  6. 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.

  7. [Measurements of the concentration of atmospheric CO2 based on OP/FTIR method and infrared reflecting scanning Fourier transform spectrometry].

    PubMed

    Wei, Ru-Yi; Zhou, Jin-Song; Zhang, Xue-Min; Yu, Tao; Gao, Xiao-Hui; Ren, Xiao-Qiang

    2014-11-01

    The present paper describes the observations and measurements of the infrared absorption spectra of CO2 on the Earth's surface with OP/FTIR method by employing a mid-infrared reflecting scanning Fourier transform spectrometry, which are the first results produced by the first prototype in China developed by the team of authors. This reflecting scanning Fourier transform spectrometry works in the spectral range 2 100-3 150 cm(-1) with a spectral resolution of 2 cm(-1). Method to measure the atmospheric molecules was described and mathematical proof and quantitative algorithms to retrieve molecular concentration were established. The related models were performed both by a direct method based on the Beer-Lambert Law and by a simulating-fitting method based on HITRAN database and the instrument functions. Concentrations of CO2 were retrieved by the two models. The results of observation and modeling analyses indicate that the concentrations have a distribution of 300-370 ppm, and show tendency that going with the variation of the environment they first decrease slowly and then increase rapidly during the observation period, and reached low points in the afternoon and during the sunset. The concentrations with measuring times retrieved by the direct method and by the simulating-fitting method agree with each other very well, with the correlation of all the data is up to 99.79%, and the relative error is no more than 2.00%. The precision for retrieving is relatively high. The results of this paper demonstrate that, in the field of detecting atmospheric compositions, OP/FTIR method performed by the Infrared reflecting scanning Fourier transform spectrometry is a feasible and effective technical approach, and either the direct method or the simulating-fitting method is capable of retrieving concentrations with high precision.

  8. Clinical review: improving the measurement of serum thyroglobulin with mass spectrometry.

    PubMed

    Hoofnagle, Andrew N; Roth, Mara Y

    2013-04-01

    Serum thyroglobulin (Tg) measurements are central to the management of patients treated for differentiated thyroid carcinoma. For decades, Tg measurements have relied on methods that are subject to interference by commonly found substances in human serum and plasma, such as Tg autoantibodies. As a result, many patients need additional imaging studies to rule out cancer persistence or recurrence that could be avoided with more sensitive and specific testing methods. The aims of this review are to: 1) briefly review the interferences common to Tg immunoassays; 2) introduce readers to liquid chromatography-tandem mass spectrometry as a method for quantifying proteins in human serum/plasma; and 3) discuss the potential benefits and limitations of the method in the quantification of serum Tg. Mass spectrometric methods have traditionally lacked the sensitivity, robustness, and throughput to be useful clinical assays. These methods failed to meet the necessary clinical benchmarks due to the nature of the mass spectrometry workflow and instrumentation. Over the past few years, there have been major advances in reagents, automation, and instrumentation for the quantification of proteins using mass spectrometry. More recently, methods using mass spectrometry to detect and quantify Tg have been developed and are of sufficient quality to be used in the management of patients. Novel serum Tg assays that use mass spectrometry may avoid the issue of autoantibody interference and other problems with currently available immunoassays for Tg. Prospective studies are needed to fully understand the potential benefits of novel Tg assays to patients and care providers.

  9. 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

  10. Midinfrared absorption measured at a lambda/400 resolution with an atomic force microscope.

    PubMed

    Houel, Julien; Homeyer, Estelle; Sauvage, Sébastien; Boucaud, Philippe; Dazzi, Alexandre; Prazeres, Rui; Ortéga, Jean-Michel

    2009-06-22

    Midinfrared absorption can be locally measured using a detection combining an atomic force microscope and a pulsed excitation. This is illustrated for the midinfrared bulk GaAs phonon absorption and for the midinfrared absorption of thin SiO(2) microdisks. We show that the signal given by the cantilever oscillation amplitude of the atomic force microscope follows the spectral dependence of the bulk material absorption. The absorption spatial resolution achieved with microdisks is around 50 nanometer for an optical excitation around 22 micrometer wavelength.

  11. Tunable, high-sensitive measurement of inter-dot transition via tunneling induced absorption

    NASA Astrophysics Data System (ADS)

    Peng, Yandong; Yang, Aihong; Chen, Bing; Li, Lei; Liu, Shande; Guo, Hongju

    2016-10-01

    A tunable, narrow absorption spectrum induced by resonant tunneling is demonstrated and proposed for measuring interdot tunneling. Tunneling-induced absorption (TIA) arises from constructive interference between different transition paths, and the large nonlinear TIA significantly enhances the total absorption. The narrow nonlinear TIA spectrum is sensitive to inter-dot tunneling, and its sensor characteristics, including sensitivity and bandwidth, are investigated in weak-coupling and strong-coupling regimes, respectively.

  12. Optical measurements of absorption changes in two-layered diffusive media

    NASA Astrophysics Data System (ADS)

    Fabbri, Francesco; Sassaroli, Angelo; Henry, Michael E.; Fantini, Sergio

    2004-04-01

    We have used Monte Carlo simulations for a two-layered diffusive medium to investigate the effect of a superficial layer on the measurement of absorption variations from optical diffuse reflectance data processed by using: (a) a multidistance, frequency-domain method based on diffusion theory for a semi-infinite homogeneous medium; (b) a differential-pathlength-factor method based on a modified Lambert-Beer law for a homogeneous medium and (c) a two-distance, partial-pathlength method based on a modified Lambert-Beer law for a two-layered medium. Methods (a) and (b) lead to a single value for the absorption variation, whereas method (c) yields absorption variations for each layer. In the simulations, the optical coefficients of the medium were representative of those of biological tissue in the near-infrared. The thickness of the first layer was in the range 0.3-1.4 cm, and the source-detector distances were in the range 1-5 cm, which is typical of near-infrared diffuse reflectance measurements in tissue. The simulations have shown that (1) method (a) is mostly sensitive to absorption changes in the underlying layer, provided that the thickness of the superficial layer is ~0.6 cm or less; (2) method (b) is significantly affected by absorption changes in the superficial layer and (3) method (c) yields the absorption changes for both layers with a relatively good accuracy of ~4% for the superficial layer and ~10% for the underlying layer (provided that the absorption changes are less than 20-30% of the baseline value). We have applied all three methods of data analysis to near-infrared data collected on the forehead of a human subject during electroconvulsive therapy. Our results suggest that the multidistance method (a) and the two-distance partial-pathlength method (c) may better decouple the contributions to the optical signals that originate in deeper tissue (brain) from those that originate in more superficial tissue layers.

  13. Measurements and Modeling of Aerosol Absorption and Single Scattering Albedo at Ambient Relative Hum

    NASA Technical Reports Server (NTRS)

    Redemann, J.; Russell, P. B.; Hamill, P.

    2000-01-01

    Uncertainties in the aerosol single scattering albedo have been identified to be an important source of errors in current large-scale model estimates of the direct aerosol radiative forcing of climate. A number of investigators have obtained estimates of the single scattering albedo from a variety of remote sensing and in situ measurements during aerosol field experiments. During the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX, 1996) for example, estimates of the aerosol single scattering albedo were obtained (1) as a best-fit parameter in comparing radiative flux changes measured by airborne pyranometer to those computed from independently measured aerosol properties; (2) from estimates of the aerosol complex index of refraction derived using a combination of airborne sunphotometer, lidar backscatter and in situ size distribution measurements; and (3) from airborne measurements of aerosol scattering and absorption using nephelometers and absorption photometers. In this paper, we briefly compare the results of the latter two methods for two TARFOX case studies, since those techniques provide height-resolved information about the aerosol single scattering albedo. Estimates of the aerosol single scattering albedo from nephelometer and absorption photometer measurements require knowledge of the scattering and absorption humidification (i.e., the increase in these properties in response to an increase in ambient relative humidity), since both measurements are usually carried out at a relative humidity different from the ambient atmosphere. In principle, the scattering humidification factor can be measured, but there is currently no technique widely available to measure the absorption of an aerosol sample as a function of relative humidity. Frequently, for lack of better knowledge, the absorption humidification is assumed to be unity (meaning that there is no change in aerosol absorption due to an increase in ambient relative humidity). This

  14. Impurity measurements in semiconductor materials using trace element accelerator mass spectrometry

    NASA Astrophysics Data System (ADS)

    McDaniel, F. D.; Datar, S. A.; Nigam, M.; Ravi Prasad, G. V.

    2002-05-01

    Accelerator mass spectrometry (AMS) is commonly used to determine the abundance ratios of long-lived isotopes such as 10B, 14C, 36Cl, 129I, etc. to their stable counterparts at levels as low as 10 -16. Secondary ion mass spectrometry (SIMS) is routinely used to determine impurity levels in materials by depth profiling techniques. Trace-element accelerator mass spectrometry (TEAMS) is a combination of AMS and SIMS, presently being used at the University of North Texas, for high-sensitivity (ppb) impurity analyses of stable isotopes in semiconductor materials. The molecular break-up characteristics of AMS are used with TEAMS to remove the molecular interferences present in SIMS. Measurements made with different substrate/impurity combinations demonstrate that TEAMS has higher sensitivity for many elements than other techniques such as SIMS and can assist with materials characterization issues. For example, measurements of implanted As in the presence of Ge in Ge xSi 1- x/Si is difficult with SIMS because of molecular interferences from 74GeH, 29Si 30Si 16O, etc. With TEAMS, the molecular interferences are removed and higher sensitivities are obtained. Measured substrates include Si, SiGe, CoSi 2, GaAs and GaN. Measured impurities include B, N, F, Mg, P, Cl, Cr, Fe, Ni, Co, Cu, Zn, Ge, As, Se, Mo, Sn and Sb. A number of measurements will be presented to illustrate the range and power of TEAMS.

  15. Quantifying uncertainty in the measurement of arsenic in suspended particulate matter by Atomic Absorption Spectrometry with hydride generator

    PubMed Central

    2011-01-01

    Arsenic is the toxic element, which creates several problems in human being specially when inhaled through air. So the accurate and precise measurement of arsenic in suspended particulate matter (SPM) is of prime importance as it gives information about the level of toxicity in the environment, and preventive measures could be taken in the effective areas. Quality assurance is equally important in the measurement of arsenic in SPM samples before making any decision. The quality and reliability of the data of such volatile elements depends upon the measurement of uncertainty of each step involved from sampling to analysis. The analytical results quantifying uncertainty gives a measure of the confidence level of the concerned laboratory. So the main objective of this study was to determine arsenic content in SPM samples with uncertainty budget and to find out various potential sources of uncertainty, which affects the results. Keeping these facts, we have selected seven diverse sites of Delhi (National Capital of India) for quantification of arsenic content in SPM samples with uncertainty budget following sampling by HVS to analysis by Atomic Absorption Spectrometer-Hydride Generator (AAS-HG). In the measurement of arsenic in SPM samples so many steps are involved from sampling to final result and we have considered various potential sources of uncertainties. The calculation of uncertainty is based on ISO/IEC17025: 2005 document and EURACHEM guideline. It has been found that the final results mostly depend on the uncertainty in measurement mainly due to repeatability, final volume prepared for analysis, weighing balance and sampling by HVS. After the analysis of data of seven diverse sites of Delhi, it has been concluded that during the period from 31st Jan. 2008 to 7th Feb. 2008 the arsenic concentration varies from 1.44 ± 0.25 to 5.58 ± 0.55 ng/m3 with 95% confidence level (k = 2). PMID:21466671

  16. Development of optical coatings for 157-nm lithography. II. Reflectance, absorption, and scatter measurement

    NASA Astrophysics Data System (ADS)

    Otani, Minoru; Biro, Ryuji; Ouchi, Chidane; Hasegawa, Masanobu; Suzuki, Yasuyuki; Sone, Kazuho; Niisaka, Shunsuke; Saito, Tadahiko; Saito, Jun; Tanaka, Akira

    2002-06-01

    The total loss that can be suffered by an antireflection (AR) coating consists of reflectance loss, absorption loss, and scatter loss. To separate these losses we developed a calorimetric absorption measurement apparatus and an ellipsoidal Coblentz hemisphere based scatterometer for 157-nm optics. Reflectance, absorption, and scatter of AR coatings were measured with these apparatuses. The AR coating samples were supplied by Japanese vendors. Each AR coating as supplied was coated with the vendor's coating design by that vendor's coating process. Our measurement apparatuses, methods, and results for these AR coatings are presented here.

  17. 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.

  18. Cavity ring-down spectroscopy (CRDS) system for measuring atmospheric mercury using differential absorption

    NASA Astrophysics Data System (ADS)

    Pierce, A.; Obrist, D.; Moosmuller, H.; Moore, C.

    2012-04-01

    Atmospheric elemental mercury (Hg0) is a globally pervasive element that can be transported and deposited to remote ecosystems where it poses — particularly in its methylated form — harm to many organisms including humans. Current techniques for measurement of atmospheric Hg0 require several liters of sample air and several minutes for each analysis. Fast-response (i.e., 1 second or faster) measurements would improve our ability to understand and track chemical cycling of mercury in the atmosphere, including high frequency Hg0 fluctuations, sources and sinks, and chemical transformation processes. We present theory, design, challenges, and current results of our new prototype sensor based on cavity ring-down spectroscopy (CRDS) for fast-response measurement of Hg0 mass concentrations. CRDS is a direct absorption technique that implements path-lengths of multiple kilometers in a compact absorption cell using high-reflectivity mirrors, thereby improving sensitivity and reducing sample volume compared to conventional absorption spectroscopy. Our sensor includes a frequency-doubled, dye-laser emitting laser pulses tunable from 215 to 280 nm, pumped by a Q-switched, frequency tripled Nd:YAG laser with a pulse repetition rate of 50 Hz. We present how we successfully perform automated wavelength locking and stabilization of the laser to the peak Hg0 absorption line at 253.65 nm using an external isotopically-enriched mercury (202Hg0) cell. An emphasis of this presentation will be on the implementation of differential absorption measurement whereby measurements are alternated between the peak Hg0 absorption wavelength and a nearby wavelength "off" the absorption line. This can be achieved using a piezo electric tuning element that allows for pulse-by-pulse tuning and detuning of the laser "online" and "offline" of the Hg absorption line, and thereby allows for continuous correction of baseline extinction losses. Unexpected challenges with this approach included

  19. [Study of high temperature water vapor concentration measurement method based on absorption spectroscopy].

    PubMed

    Chen, Jiu-ying; Liu, Jian-guo; He, Jun-feng; He, Ya-bai; Zhang, Guang-le; Xu, Zhen-yu; Gang, Qiang; Wang, Liao; Yao, Lu; Yuan, Song; Ruan, Jun; Dai, Yun-hai; Kan, Rui-feng

    2014-12-01

    Tunable diode laser absorption spectroscopy (TDLAS) has been developed to realize the real-time and dynamic measurement of the combustion temperature, gas component concentration, velocity and other flow parameters, owing to its high sensitivity, fast time response, non-invasive character and robust nature. In order to obtain accurate water vapor concentration at high temperature, several absorption spectra of water vapor near 1.39 μm from 773 to 1273 K under ordinary pressure were recorded in a high temperature experiment setup using a narrow band diode laser. The absorbance of high temperature absorption spectra was calculated by combined multi-line nonlinear least squares fitting method. Two water vapor absorption lines near 7154.35 and 7157.73 cm(-1) were selected for measurement of water vapor at high temperature. A model method for high temperature water vapor concentration was first proposed. Water vapor concentration from the model method at high temperature is in accordance with theoretical reasoning, concentration measurement standard error is less than 0.2%, and the relative error is less than 6%. The feasibility of this measuring method is verified by experiment.

  20. A benchmarking method to measure dietary absorption efficiency of chemicals by fish.

    PubMed

    Xiao, Ruiyang; Adolfsson-Erici, Margaretha; Åkerman, Gun; McLachlan, Michael S; MacLeod, Matthew

    2013-12-01

    Understanding the dietary absorption efficiency of chemicals in the gastrointestinal tract of fish is important from both a scientific and a regulatory point of view. However, reported fish absorption efficiencies for well-studied chemicals are highly variable. In the present study, the authors developed and exploited an internal chemical benchmarking method that has the potential to reduce uncertainty and variability and, thus, to improve the precision of measurements of fish absorption efficiency. The authors applied the benchmarking method to measure the gross absorption efficiency for 15 chemicals with a wide range of physicochemical properties and structures. They selected 2,2',5,6'-tetrachlorobiphenyl (PCB53) and decabromodiphenyl ethane as absorbable and nonabsorbable benchmarks, respectively. Quantities of chemicals determined in fish were benchmarked to the fraction of PCB53 recovered in fish, and quantities of chemicals determined in feces were benchmarked to the fraction of decabromodiphenyl ethane recovered in feces. The performance of the benchmarking procedure was evaluated based on the recovery of the test chemicals and precision of absorption efficiency from repeated tests. Benchmarking did not improve the precision of the measurements; after benchmarking, however, the median recovery for 15 chemicals was 106%, and variability of recoveries was reduced compared with before benchmarking, suggesting that benchmarking could account for incomplete extraction of chemical in fish and incomplete collection of feces from different tests. © 2013 SETAC.

  1. Direct measurements of temperature-dependent laser absorptivity of metal powders

    DOE PAGES

    Rubenchik, A.; Wu, S.; Mitchell, S.; ...

    2015-08-12

    Here, a compact system is developed to measure laser absorptivity for a variety of powder materials (metals, ceramics, etc.) with different powder size distributions and thicknesses. The measured results for several metal powders are presented. The results are consistent with those from ray tracing calculations.

  2. Direct measurements of temperature-dependent laser absorptivity of metal powders

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

    Rubenchik, A.; Wu, S.; Mitchell, S.

    Here, a compact system is developed to measure laser absorptivity for a variety of powder materials (metals, ceramics, etc.) with different powder size distributions and thicknesses. The measured results for several metal powders are presented. The results are consistent with those from ray tracing calculations.

  3. Temperature measurement using ultraviolet laser absorption of carbon dioxide behind shock waves.

    PubMed

    Oehlschlaeger, Matthew A; Davidson, David F; Jeffries, Jay B

    2005-11-01

    A diagnostic for microsecond time-resolved temperature measurements behind shock waves, using ultraviolet laser absorption of vibrationally hot carbon dioxide, is demonstrated. Continuous-wave laser radiation at 244 and 266 nm was employed to probe the spectrally smooth CO2 ultraviolet absorption, and an absorbance ratio technique was used to determine temperature. Measurements behind shock waves in both nonreacting and reacting (ignition) systems were made, and comparisons with isentropic and constant-volume calculations are reported.

  4. 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.

  5. 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

  6. Water vapour foreign-continuum absorption in near-infrared windows from laboratory measurements.

    PubMed

    Ptashnik, Igor V; McPheat, Robert A; Shine, Keith P; Smith, Kevin M; Williams, R Gary

    2012-06-13

    For a long time, it has been believed that atmospheric absorption of radiation within wavelength regions of relatively high infrared transmittance (so-called 'windows') was dominated by the water vapour self-continuum, that is, spectrally smooth absorption caused by H(2)O--H(2)O pair interaction. Absorption due to the foreign continuum (i.e. caused mostly by H(2)O--N(2) bimolecular absorption in the Earth's atmosphere) was considered to be negligible in the windows. We report new retrievals of the water vapour foreign continuum from high-resolution laboratory measurements at temperatures between 350 and 430 K in four near-infrared windows between 1.1 and 5 μm (9000-2000 cm(-1)). Our results indicate that the foreign continuum in these windows has a very weak temperature dependence and is typically between one and two orders of magnitude stronger than that given in representations of the continuum currently used in many climate and weather prediction models. This indicates that absorption owing to the foreign continuum may be comparable to the self-continuum under atmospheric conditions in the investigated windows. The calculated global-average clear-sky atmospheric absorption of solar radiation is increased by approximately 0.46 W m(-2) (or 0.6% of the total clear-sky absorption) by using these new measurements when compared with calculations applying the widely used MTCKD (Mlawer-Tobin-Clough-Kneizys-Davies) foreign-continuum model.

  7. The Importance of Optical Pathlength Control for Plasma Absorption Measurements

    NASA Technical Reports Server (NTRS)

    Cruden, Brett A.; Rao, M. V. V. S.; Sharma, Surendra P.; Meyyappan, M.; Partridge, Harry (Technical Monitor)

    2001-01-01

    An inductively coupled GEC Cell with modified viewing ports has been used to measure in-situ absorption in CF4 plasmas via Fourier Transform Infrared Spectroscopy, and the results compared to those obtained in a standard viewport configuration. The viewing ports were modified so that the window boundary is inside, rather than outside, of the GEC cell. Because the absorption obtained is a spatially integrated absorption, measurements made represent an averaging of absorbing species inside and outside of the plasma. This modification is made to reduce this spatial averaging and thus allow a more accurate estimation of neutral species concentrations and temperatures within the plasmas. By reducing this pathlength, we find that the apparent CF4 consumption increases from 65% to 95% and the apparent vibrational temperature of CF4 rises by 50-75 K. The apparent fraction of etch product SiF4 decreases from 4% to 2%. The data suggests that these density changes may be due to significant temperature gradients between the plasma and chamber viewports.

  8. Measurement of transient gas flow parameters by diode laser absorption spectroscopy

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

    Bolshov, M A; Kuritsyn, Yu A; Liger, V V

    2015-04-30

    An absorption spectrometer based on diode lasers is developed for measuring two-dimension maps of temperature and water vapour concentration distributions in the combustion zones of two mixing supersonic flows of fuel and oxidiser in the single run regime. The method of measuring parameters of hot combustion zones is based on detection of transient spectra of water vapour absorption. The design of the spectrometer considerably reduces the influence of water vapour absorption along the path of a sensing laser beam outside the burning chamber. The optical scheme is developed, capable of matching measurement results in different runs of mixture burning. Amore » new algorithm is suggested for obtaining information about the mixture temperature by constructing the correlation functions of the experimental spectrum with those simulated from databases. A two-dimensional map of temperature distribution in a test chamber is obtained for the first time under the conditions of plasma-induced combusion of the ethylene – air mixture. (laser applications and other topics in quantum electronics)« less

  9. O absorption measurements in an engineering-scale high-pressure coal gasifier

    NASA Astrophysics Data System (ADS)

    Sun, Kai; Sur, Ritobrata; Jeffries, Jay B.; Hanson, Ronald K.; Clark, Tommy; Anthony, Justin; Machovec, Scott; Northington, John

    2014-10-01

    A real-time, in situ water vapor (H2O) sensor using a tunable diode laser near 1,352 nm was developed to continuously monitor water vapor in the synthesis gas of an engineering-scale high-pressure coal gasifier. Wavelength-scanned wavelength-modulation spectroscopy with second harmonic detection (WMS-2 f) was used to determine the absorption magnitude. The 1 f-normalized, WMS-2 f signal (WMS-2 f/1 f) was insensitive to non-absorption transmission losses including beam steering and light scattering by the particulate in the synthesis gas. A fitting strategy was used to simultaneously determine the water vapor mole fraction and the collisional-broadening width of the transition from the scanned 1 f-normalized WMS-2 f waveform at pressures up to 15 atm, which can be used for large absorbance values. This strategy is analogous to the fitting strategy for wavelength-scanned direct absorption measurements. In a test campaign at the US National Carbon Capture Center, the sensor demonstrated a water vapor detection limit of ~800 ppm (25 Hz bandwidth) at conditions with more than 99.99 % non-absorption transmission losses. Successful unattended monitoring was demonstrated over a 435 h period. Strong correlations between the sensor measurements and transient gasifier operation conditions were observed, demonstrating the capability of laser absorption to monitor the gasification process.

  10. Sound absorption by suspensions of nonspherical particles: Measurements compared with predictions using various particle sizing techniques

    NASA Astrophysics Data System (ADS)

    Richards, Simon D.; Leighton, Timothy G.; Brown, Niven R.

    2003-10-01

    Knowledge of the particle size distribution is required in order to predict ultrasonic absorption in polydisperse particulate suspensions. This paper shows that the method used to measure the particle size distribution can lead to important differences in the predicted absorption. A reverberation technique developed for measuring ultrasonic absorption by suspended particles is used to measure the absorption in suspensions of nonspherical particles. Two types of particulates are studied: (i) kaolin (china clay) particles which are platelike in form; and (ii) calcium carbonate particles which are more granular. Results are compared to theoretical predictions of visco-inertial absorption by suspensions of spherical particles. The particle size distributions, which are required for these predictions, are measured by laser diffraction, gravitational sedimentation and centrifugal sedimentation, all of which assume spherical particles. For a given sample, each sizing technique yields a different size distribution, leading to differences in the predicted absorption. The particle size distributions obtained by gravitational and centrifugal sedimentation are reinterpreted to yield a representative size distribution of oblate spheroids, and predictions for absorption by these spheroids are compared with the measurements. Good agreement between theory and measurement for the flat kaolin particles is obtained, demonstrating that these particles can be adequately represented by oblate spheroids.

  11. Isolation and Puification of Uranium Isotopes for Measurement by Mass-Spectrometry (233, 234, 235, 236, 238U) and Alpha Spectrometry (232U)

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

    Marinelli, R; Hamilton, T; Brown, T

    2006-05-30

    This report describes a standardized methodology used by researchers from the Center for Accelerator Mass Spectrometry (CAMS) (Energy and Environment Directorate) and the Environmental Radiochemistry Group (Chemistry and Materials Science Directorate) at the Lawrence Livermore National Laboratory (LLNL) for the full isotopic analysis of uranium from solution. The methodology has largely been developed for use in characterizing the uranium composition of selected nuclear materials but may also be applicable to environmental studies and assessments of public, military or occupational exposures to uranium using in-vitro bioassay monitoring techniques. Uranium isotope concentrations and isotopic ratios are measured using a combination of Multimore » Collector Inductively Coupled Plasma Mass Spectrometry (MC ICP-MS), Accelerator Mass Spectrometry (AMS) and Alpha Spectrometry.« less

  12. Microwave measurements of the absolute values of absorption by water vapour in the atmosphere.

    PubMed

    Hogg, D C; Guiraud, F O

    1979-05-31

    MEASUREMENT of the absolute value of absorption by water vapour at microwave frequencies is difficult because the effect is so small. Far in the wings of the absorption lines, in the so-called 'windows' of the spectrum, it is especially difficult to achieve high accuracy in the free atmosphere. But it is in these windows that the behaviour of the absorption is important from both applied and scientific points of view. Satellite communications, remote sensing of the atmosphere, and radioastronomy, are all influenced by this behaviour. Measurements on an Earth-space path are reported here; the results indicate a nonlinear relationship between absorption and water-vapour content.

  13. Simple test of intestinal calcium absorption measured by stable strontium.

    PubMed Central

    Milsom, S; Ibbertson, K; Hannan, S; Shaw, D; Pybus, J

    1987-01-01

    A clinical test of intestinal calcium absorption has been developed using non-radioactive stable strontium as a calcium tracer. In nine elderly subjects there was a close correlation between the fractional absorption of strontium and radioactive calcium (45Ca) during a five hour period after the simultaneous oral administration of the two tracers. Comparable precision was achieved with each tracer in six subjects in whom the test was repeated after two weeks. The effect of food on strontium absorption was examined in a further 33 normal subjects (age 21-60 years), and the administration of the strontium with a standard breakfast was shown to reduce the variance at individual time points. A simplified test in which serum strontium concentration was measured four hours after the oral dose given with a standard breakfast was adopted as the routine procedure. The normal range (mean (2 SD], established over 97 tests in 53 patients, was 7.0-18.0% of the dose in the extracellular fluid. A further 30 patients with possible disorders of calcium absorption (10 with primary hyperparathyroidism and 20 with coeliac disease) were studied by this standard test. In both groups of patients the mean four hour strontium values were significantly different from normal. This standard strontium absorption test allows assessment of calcium absorption with sufficient sensitivity and precision to have a wide application in clinical practice. PMID:3115389

  14. Tunable diode laser measurements of HO2NO2 absorption coefficients near 12.5 microns

    NASA Technical Reports Server (NTRS)

    May, R. D.; Molina, L. T.; Webster, C. R.

    1988-01-01

    A tunable diode laser spectrometer has been used to measure absorption coefficients of peroxynitric acid (HO2NO2) near the 803/cm Q branch. HO2NO2 concentrations in a low-pressure flowing gas mixture were determined from chemical titration procedures and UV absorption spectroscopy. The diode laser measured absorption coefficients, at a spectral resolution of better than 0.001/cm, are about 10 percent larger than previous Fourier transform infrared measurements made at a spectral resolution of 0.06/cm.

  15. Measurements of zinc absorption: application and interpretation in research designed to improve human zinc nutriture.

    PubMed

    Hambidge, K Michael; Miller, Leland V; Tran, Cuong D; Krebs, Nancy F

    2005-11-01

    The focus of this paper is on the application of measurements of zinc absorption in human research, especially studies designed to assess the efficacy of intervention strategies to prevent and manage zinc deficiency in populations. Emphasis is given to the measurement of quantities of zinc absorbed rather than restricting investigations to measurements of fractional absorption of zinc. This is especially important when determining absorption of zinc from the diet, whether it be the habitual diet or an intervention diet under evaluation. Moreover, measurements should encompass all meals for a minimum of one day with the exception of some pilot studies. Zinc absorption is primarily via an active saturable transport process into the enterocytes of the proximal small intestine. The relationship between quantity of zinc absorbed and the quantity ingested is best characterized by saturable binding models. When applied to human studies that have sufficient data to examine dose-response relationships, efficiency of absorption is high until approximately 50-60% maximal absorption is achieved, even with moderate phytate intakes. This also coincides approximately with the quantity of absorbed zinc necessary to meet physiologic requirements. Efficiency of absorption with intakes that exceed this level is low or very low. These observations have important practical implications for the design and interpretation of intervention studies to prevent zinc deficiency. They also suggest the potential utility of measurements of the quantity of zinc absorbed when evaluating the zinc status of populations.

  16. The effect of ISM absorption on stellar activity measurements and its relevance for exoplanet studies

    NASA Astrophysics Data System (ADS)

    Fossati, L.; Marcelja, S. E.; Staab, D.; Cubillos, P. E.; France, K.; Haswell, C. A.; Ingrassia, S.; Jenkins, J. S.; Koskinen, T.; Lanza, A. F.; Redfield, S.; Youngblood, A.; Pelzmann, G.

    2017-05-01

    Past ultraviolet and optical observations of stars hosting close-in Jupiter-mass planets have shown that some of these stars present an anomalously low chromospheric activity, significantly below the basal level. For the hot Jupiter planet host WASP-13, observations have shown that the apparent lack of activity is possibly caused by absorption from the intervening interstellar medium (ISM). Inspired by this result, we study the effect of ISM absorption on activity measurements (S and log R 'HK indices) for main-sequence late-type stars. To this end, we employ synthetic stellar photospheric spectra combined with varying amounts of chromospheric emission and ISM absorption. We present the effect of ISM absorption on activity measurements by varying several instrumental (spectral resolution), stellar (projected rotational velocity, effective temperature, and chromospheric emission flux), and ISM parameters (relative velocity between stellar and ISM Ca II lines, broadening b-parameter, and Ca II column density). We find that for relative velocities between the stellar and ISM lines smaller than 30-40 km s-1 and for ISM Ca II column densities log NCaII ⪆ 12, the ISM absorption has a significant influence on activity measurements. Direct measurements and three dimensional maps of the Galactic ISM absorption indicate that an ISM Ca II column density of log NCaII = 12 is typically reached by a distance of about 100 pc along most sight lines. In particular, for a Sun-like star lying at a distance greater than 100 pc, we expect a depression (bias) in the log R'HK value larger than 0.05-0.1 dex, about the same size as the typical measurement and calibration uncertainties on this parameter. This work shows that the bias introduced by ISM absorption must always be considered when measuring activity for stars lying beyond 100 pc. We also consider the effect of multiple ISM absorption components. We discuss the relevance of this result for exoplanet studies and revise the

  17. [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.

  18. Airborne differential absorption lidar system for measurements of atmospheric water vapor and aerosols

    NASA Technical Reports Server (NTRS)

    Carter, Arlen F.; Allen, Robert J.; Mayo, M. Neale; Butler, Carolyn F.; Grossman, Benoist E.; Ismail, Syed; Grant, William B.; Browell, Edward V.; Higdon, Noah S.; Mayor, Shane D.; hide

    1994-01-01

    An airborne differential absorption lidar (DIAL) system has been developed at the NASA Langley Research Center for remote measurements of atmospheric water vapor (H2O) and aerosols. A solid-state alexandrite laser with a 1-pm linewidth and greater than 99.85% spectral purity was used as the on-line transmitter. Solid-state avalanche photodiode detector technology has replaced photomultiplier tubes in the receiver system, providing an average increase by a factor of 1.5-2.5 in the signal-to-noise ratio of the H2O measurement. By incorporating advanced diagnostic and data-acquisition instrumentation into other subsystems, we achieved additional improvements in system operational reliability and measurement accuracy. Laboratory spectroscopic measurements of H2O absorption-line parameters were performed to reduce the uncertainties in our knowledge of the absorption cross sections. Line-center H2O absorption cross sections were determined, with errors of 3-6%, for more than 120 lines in the 720-nm region. Flight tests of the system were conducted during 1989-1991 on the NASA Wallops Flight Facility Electra aircraft, and extensive intercomparison measurements were performed with dew-point hygrometers and H2O radiosondes. The H2O distributions measured with the DIAL system differed by less than 10% from the profiles determined with the in situ probes in a variety of atmospheric conditions.

  19. 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.

  20. 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).

  1. Absorption/Transmission Measurements of PSAP Particle-Laden Filters from the Biomass Burning Observation Project (BBOP) Field Campaign

    PubMed Central

    Presser, Cary; Nazarian, Ashot; Conny, Joseph M.; Chand, Duli; Sedlacek, Arthur; Hubbe, John M.

    2017-01-01

    Absorptivity measurements with a laser-heating approach, referred to as the laser-driven thermal reactor (LDTR), were carried out in the infrared and applied at ambient (laboratory) non-reacting conditions to particle-laden filters from a three-wavelength (visible) particle/soot absorption photometer (PSAP). The particles were obtained during the Biomass Burning Observation Project (BBOP) field campaign. The focus of this study was to determine the particle absorption coefficient from field-campaign filter samples using the LDTR approach, and compare results with other commercially available instrumentation (in this case with the PSAP, which has been compared with numerous other optical techniques). Advantages of the LDTR approach include 1) direct estimation of material absorption from temperature measurements (as opposed to resolving the difference between the measured reflection/scattering and transmission), 2) information on the filter optical properties, and 3) identification of the filter material effects on particle absorption (e.g., leading to particle absorption enhancement or shadowing). For measurements carried out under ambient conditions, the particle absorptivity is obtained with a thermocouple placed flush with the filter back surface and the laser probe beam impinging normal to the filter particle-laden surface. Thus, in principle one can employ a simple experimental arrangement to measure simultaneously both the transmissivity and absorptivity (at different discrete wavelengths) and ascertain the particle absorption coefficient. For this investigation, LDTR measurements were carried out with PSAP filters (pairs with both blank and exposed filters) from eight different days during the campaign, having relatively light but different particle loadings. The observed particles coating the filters were found to be carbonaceous (having broadband absorption characteristics). The LDTR absorption coefficient compared well with results from the PSAP. The

  2. Absorption/Transmission Measurements of PSAP Particle-Laden Filters from the Biomass Burning Observation Project (BBOP) Field Campaign.

    PubMed

    Presser, Cary; Nazarian, Ashot; Conny, Joseph M; Chand, Duli; Sedlacek, Arthur; Hubbe, John M

    2017-01-01

    Absorptivity measurements with a laser-heating approach, referred to as the laser-driven thermal reactor (LDTR), were carried out in the infrared and applied at ambient (laboratory) non-reacting conditions to particle-laden filters from a three-wavelength (visible) particle/soot absorption photometer (PSAP). The particles were obtained during the Biomass Burning Observation Project (BBOP) field campaign. The focus of this study was to determine the particle absorption coefficient from field-campaign filter samples using the LDTR approach, and compare results with other commercially available instrumentation (in this case with the PSAP, which has been compared with numerous other optical techniques). Advantages of the LDTR approach include 1) direct estimation of material absorption from temperature measurements (as opposed to resolving the difference between the measured reflection/scattering and transmission), 2) information on the filter optical properties, and 3) identification of the filter material effects on particle absorption (e.g., leading to particle absorption enhancement or shadowing). For measurements carried out under ambient conditions, the particle absorptivity is obtained with a thermocouple placed flush with the filter back surface and the laser probe beam impinging normal to the filter particle-laden surface. Thus, in principle one can employ a simple experimental arrangement to measure simultaneously both the transmissivity and absorptivity (at different discrete wavelengths) and ascertain the particle absorption coefficient. For this investigation, LDTR measurements were carried out with PSAP filters (pairs with both blank and exposed filters) from eight different days during the campaign, having relatively light but different particle loadings. The observed particles coating the filters were found to be carbonaceous (having broadband absorption characteristics). The LDTR absorption coefficient compared well with results from the PSAP. The

  3. 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.

  4. Quantitative filter technique measurements of spectral light absorption by aquatic particles using a portable integrating cavity absorption meter (QFT-ICAM).

    PubMed

    Röttgers, Rüdiger; Doxaran, David; Dupouy, Cecile

    2016-01-25

    The accurate determination of light absorption coefficients of particles in water, especially in very oligotrophic oceanic areas, is still a challenging task. Concentrating aquatic particles on a glass fiber filter and using the Quantitative Filter Technique (QFT) is a common practice. Its routine application is limited by the necessary use of high performance spectrophotometers, distinct problems induced by the strong scattering of the filters and artifacts induced by freezing and storing samples. Measurements of the sample inside a large integrating sphere reduce scattering effects and direct field measurements avoid artifacts due to sample preservation. A small, portable, Integrating Cavity Absorption Meter setup (QFT-ICAM) is presented, that allows rapid measurements of a sample filter. The measurement technique takes into account artifacts due to chlorophyll-a fluorescence. The QFT-ICAM is shown to be highly comparable to similar measurements in laboratory spectrophotometers, in terms of accuracy, precision, and path length amplification effects. No spectral artifacts were observed when compared to measurement of samples in suspension, whereas freezing and storing of sample filters induced small losses of water-soluble pigments (probably phycoerythrins). Remaining problems in determining the particulate absorption coefficient with the QFT-ICAM are strong sample-to-sample variations of the path length amplification, as well as fluorescence by pigments that is emitted in a different spectral region than that of chlorophyll-a.

  5. 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.

  6. Two-photon absorption measurements of deep UV transmissible materials at 213  nm.

    PubMed

    Patankar, S; Yang, S T; Moody, J D; Swadling, G F; Erlandson, A C; Bayramian, A J; Barker, D; Datte, P; Acree, R L; Pepmeier, B; Madden, R E; Borden, M R; Ross, J S

    2017-10-20

    We report on two-photon absorption measurements at 213 nm of deep UV transmissible media, including LiF, MgF 2 , CaF 2 , BaF 2 , sapphire (Al 2 O 3 ), and high-purity grades of fused-silica (SiO 2 ). A high-stability 24 ps Nd:YAG laser operating at the 5th harmonic (213 nm) was used to generate a high-intensity, long-Rayleigh-length Gaussian focus inside the samples. The measurements of the fluoride crystals and sapphire indicate two-photon absorption coefficients between 0.004 and 0.82 cm/GW. We find that different grades of fused silica performed near identically for two-photon absorption; however, there are differences in linear losses associated with purity. A low two-photon absorption cross section is measured for MgF 2 , making it an ideal material for the propagation of high-intensity deep UV lasers.

  7. Computed tomography measurement of gaseous fuel concentration by infrared laser light absorption

    NASA Astrophysics Data System (ADS)

    Kawazoe, Hiromitsu; Inagaki, Kazuhisa; Emi, Y.; Yoshino, Fumio

    1997-11-01

    A system to measure gaseous hydrocarbon distributions was devised, which is based on IR light absorption by C-H stretch mode of vibration and computed tomography method. It is called IR-CT method in the paper. Affection of laser light power fluctuation was diminished by monitoring source light intensity by the second IR light detector. Calibration test for methane fuel was carried out to convert spatial data of line absorption coefficient into quantitative methane concentration. This system was applied to three flow fields. The first is methane flow with lifted flame which is generated by a gourd-shaped fuel nozzle. Feasibility of the IR-CT method was confirmed through the measurement. The second application is combustion field with diffusion flame. Calibration to determine absorptivity was undertaken, and measured line absorption coefficient was converted spatial fuel concentration using corresponding temperature data. The last case is modeled in cylinder gas flow of internal combustion engine, where gaseous methane was led to the intake valve in steady flow state. The fuel gas flow simulates behavior of gaseous gasoline which is evaporated at intake valve tulip. Computed tomography measurement of inner flow is essentially difficult because of existence of surrounding wall. In this experiment, IR laser beam was led to planed portion by IR light fiber. It is found that fuel convection by airflow takes great part in air-fuel mixture formation and the developed IR-CT system to measure fuel concentration is useful to analyze air-fuel mixture formation process and to develop new combustors.

  8. 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.

  9. 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.

  10. High-temperature measurements of methane and acetylene using quantum cascade laser absorption near 8 μm

    NASA Astrophysics Data System (ADS)

    Sajid, M. B.; Javed, T.; Farooq, A.

    2015-04-01

    The mid-infrared wavelength region near 8 μm contains absorption bands of several molecules such as water vapor, hydrogen peroxide, nitrous oxide, methane and acetylene. A new laser absorption sensor based on the ν4 band of methane and the ν4+ν5 band of acetylene is reported for interference-free, time-resolved measurements under combustion-relevant conditions. A detailed line-selection procedure was used to identify optimum transitions. Methane and acetylene were measured at the line centers of Q12 (1303.5 cm-1) and P23 (1275.5 cm-1) transitions, respectively. High-temperature absorption cross sections of methane and acetylene were measured at peaks (on-line) and valleys (off-line) of the selected absorption transitions. The differential absorption strategy was employed to eliminate interference absorption from large hydrocarbons. Experiments were performed behind reflected shock waves over a temperature range of 1200-2200 K, between pressures of 1-4 atm. The diagnostics were then applied to measure the respective species time-history profiles during the shock-heated pyrolysis of n-pentane.

  11. 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.

  12. Differential Absorption Lidar (DIAL) Measurements from Air and Space

    NASA Technical Reports Server (NTRS)

    Browell, E. V.; Ismail, S.; Grant, W. B.

    1998-01-01

    Differential absorption lidar (DIAL) systems have been used for the measurement of ozone, water vapor, and aerosols from aircraft platforms for over 18 years, yielding new insights into atmospheric chemistry, composition, and dynamics in large-scale field experiments conducted all over the world. The successful deployment of the lidar in-space technology experiment (LITE) in September 1994 demonstrated that space-based lidars can also collect valuable information on the global atmosphere. This paper reviews some of the contributions of the NASA Langley Research Center's airborne ozone and water vapor DIAL systems and space-based LITE system to the understanding of the atmosphere and discusses the feasibility and advantages of putting DIAL systems in space for routine atmospheric measurements of ozone and/or water vapor and aerosols and clouds. The technology and applications of the differential absorption lidar (DIAL) technique have progressed significantly since the first DIAL measurements of Schotland, and airborne DIAL measurements of ozone and water vapor are frequently being made in a wide range of field experiments. In addition, plans are underway to develop DIAL systems for use on satellites for continuous global measurements. This paper will highlight the history of airborne lidar and DIAL systems, summarize the major accomplishments of the NASA Langley DIAL program, and discuss specifications and goals for DIAL systems in space.

  13. Portable Instrument to Measure CDOM Light Absorption in Aquatic Systems: WPI Success Story

    NASA Technical Reports Server (NTRS)

    2001-01-01

    World Precision Instruments, Inc. (WPI), of Sarasota, FL, in collaboration with NASA's John C. Stennis Space Center, has developed an innovative instrument to accurately measure Colored Dissolved Organic Matter (CDOM) absorption in the field. This successful collaboration has culminated in an exciting new device, called the UltraPath, now commercially available through WPI. Traditional methods of measuring absorption of dissolved materials require special handling and storage prior to measurement. Use of laboratory spectrophotometers as the measuring devices have proven time consuming, cumbersome, and delicate to handle. The UltraPath provides a low-cost, highly sensitive, rugged, portable system that is capable of high sensitivity measurements in widely divergent waters.

  14. 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.

  15. Deriving brown carbon from multiwavelength absorption measurements: Method and application to AERONET and Aethalometer observations

    DOE PAGES

    Wang, X.; Heald, C. L.; Sedlacek, A.; ...

    2016-10-13

    The radiative impact of organic aerosols (OA) is a large source of uncertainty in estimating the global direct radiative effect (DRE) of aerosols. This radiative impact includes not only light scattering but also light absorption from a subclass of OA referred to as brown carbon (BrC). However the absorption properties of BrC are poorly understood leading to large uncertainties in modelling studies. To obtain observational constraints from measurements, a simple Absorption Ångström Exponent (AAE) method is often used to separate the contribution of BrC absorption from that of black carbon (BC). However, this attribution method is based on assumptions regardingmore » the spectral dependence of BC that are often violated in the ambient atmosphere. Here we develop a new method that decreases the uncertainties associated with estimating BrC absorption. By applying this method to multi-wavelength absorption aerosol optical depth (AAOD) measurements at AERONET sites worldwide and surface aerosol absorption measurements at multiple ambient sites, we estimate that BrC globally contributes 6-40% of the absorption at 440nm. We find that the mass absorption coefficient of OA (OA-MAC) is positively correlated with BC/OA mass ratio. Based on the variability of BC properties and BC/OA emission ratio, we estimate a range of 0.05-1.2 m 2/g for OA-MAC at 440nm. Using the combination of AERONET and OMI UV absorption observations we estimate that the AAE 388/440nm for BrC is generally ~4 world-wide, with a smaller value in Europe (< 2). Our analyses of two surface sites (Cape Cod, to the southeast of Boston, and the GoAmazon2014/5 T3 site, to the west of Manaus, Brazil) reveal no significant relationship between BrC absorptivity and photochemical aging in typical urban influenced conditions. However, the absorption of BrC measured during the biomass burning season near Manaus is found to decrease with photochemical aging with a lifetime of ~1 day. This lifetime is comparable to

  16. [Reliability study on the infrared spectrometry for measuring the delta over baseline for breath 13C].

    PubMed

    Wang, Min; Wang, Zhiling; Gou, Lingyan; Zhang, Yuhui; Yang, Xiaoguang; Sha, Lei; Li, Min

    2013-03-01

    To assess the validity and reliability of the infrared spectrometry for measuring the delta over baseline for breath 13C. Twenty-four healthy adults were selected, including twelve males and twelve females. 13C-Leucine was used as tracer in stable isotope metabolic experiments. One baseline breath was collected before the tracer protocol began. Other breath samples were collected at 60, 120, 180, 195, 210, 225, 240, 255, 270 and 300 min post-tracer challenge. The delta over baseline for breath 13C was measured by the infrared spectrometry and Heliview 13C breath analyzer. No significant differences were found between the infrared spectrometry and Heliview 13C breath analyzer in measuring the delta over baseline for breath 13C. The F value and p value of two-way ANOVA were 0.29 and 0.5874 respectively. The t and p value of consistency test were 0.48 and 0.6346 respectively. The 13C infrared spectrometry can reliably measure the delta over baseline for breath 13C.

  17. 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.

  18. Application of the laser induced deflection (LID) technique for low absorption measurements in bulk materials and coatings

    NASA Astrophysics Data System (ADS)

    Triebel, W.; Mühlig, C.; Kufert, S.

    2005-10-01

    Precise absorption measurements of bulk materials and coatings upon pulsed ArF laser irradiation are presented using a compact experimental setup based on the laser induced deflection technique (LID). For absorption measurements of bulk materials the influence of pure bulk and pure surface absorption on the temperature and refractive index profile and thus for the probe beam deflection is analyzed in detail. The separation of bulk and surface absorption via the commonly used variation of the sample thickness is carried out for fused silica and calcium fluoride. The experimental results show that for the given surface polishing quality the bulk absorption coefficient of fused silica can be obtained by investigating only one sample. To avoid the drawback of different bulk and surface properties amongst a thickness series, we propose a strategy based on the LID technique to generally obtain surface and bulk absorption separately by investigating only one sample. Apart from measuring bulk absorption coefficients the LID technique is applied to determine the absorption of highly reflecting (HR) coatings on CaF2 substrates. Beside the measuring strategy the experimental results of a AlF3/LaF3 based HR coating are presented. In order to investigate a larger variety of coatings, including high transmitting coatings, a general measuring strategy based on the LID technique is proposed.

  19. In situ absorptivity measurements of metallic powders during laser powder-bed fusion additive manufacturing

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

    Trapp, Johannes; Rubenchik, Alexander M.; Guss, Gabe

    Here, the effective absorptivity of continuous wave 1070 nm laser light has been studied for bare and metal powder-coated discs of 316L stainless steel as well as for aluminum alloy 1100 and tungsten by use of direct calorimetric measurements. After carefully validating the applicability of the method, the effective absorptivity is plotted as a function of incident laser power from 30 up to ≈540 W for scanning speeds of 100, 500 and 1500 mm s –1. The effective absorptivity versus power curves of the bulk materials typically show a slight change in effective absorptivity from 30 W until the onsetmore » of the formation of a recoil pressure-induced surface depression. As observed using high-speed video, this change in surface morphology leads to an increase in absorption of the laser light. At the higher powers beyond the keyhole transition, a saturation value is reached for both bare discs and powder-coated disks. For ≈100 μm thick powder layers, the measured absorptivity was found to be two times that of the bare polished discs for low-laser power. There is a sharp decrease when full melting of the powder tracks is achieved, followed by a keyhole-driven increase at higher powers, similar to the bare disc case. It is shown that, under conditions associated with laser powder-bed fusion additive manufacturing, absorptivity values can vary greatly, and differ from both powder-layer measurements and liquid metal estimates from the literature.« less

  20. In situ absorptivity measurements of metallic powders during laser powder-bed fusion additive manufacturing

    DOE PAGES

    Trapp, Johannes; Rubenchik, Alexander M.; Guss, Gabe; ...

    2017-09-17

    Here, the effective absorptivity of continuous wave 1070 nm laser light has been studied for bare and metal powder-coated discs of 316L stainless steel as well as for aluminum alloy 1100 and tungsten by use of direct calorimetric measurements. After carefully validating the applicability of the method, the effective absorptivity is plotted as a function of incident laser power from 30 up to ≈540 W for scanning speeds of 100, 500 and 1500 mm s –1. The effective absorptivity versus power curves of the bulk materials typically show a slight change in effective absorptivity from 30 W until the onsetmore » of the formation of a recoil pressure-induced surface depression. As observed using high-speed video, this change in surface morphology leads to an increase in absorption of the laser light. At the higher powers beyond the keyhole transition, a saturation value is reached for both bare discs and powder-coated disks. For ≈100 μm thick powder layers, the measured absorptivity was found to be two times that of the bare polished discs for low-laser power. There is a sharp decrease when full melting of the powder tracks is achieved, followed by a keyhole-driven increase at higher powers, similar to the bare disc case. It is shown that, under conditions associated with laser powder-bed fusion additive manufacturing, absorptivity values can vary greatly, and differ from both powder-layer measurements and liquid metal estimates from the literature.« less

  1. Interpreting measurements obtained with the cloud absorption radiometer

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The software developed for the analysis of data from the Cloud Absorption Radiometer (CAR) is discussed. The CAR is a multichannel radiometer designed to measure the radiation field in the middle of an optically thick cloud (the diffusion domain). It can also measure the surface albedo and escape function. The instrument currently flies on a C-131A aircraft operated by the University of Washington. Most of this data was collected during the First International satellite cloud climatology project Regional Experiment (FIRE) Marine Stratocumulus Intensive Field Observation program off San Diego during July 1987. Earlier flights of the CAR have also been studied.

  2. Re-Evaluation of Dust Radiative Forcing Using Remote Measurements of Dust Absorption

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram J.; Tanre, Didier; Karnieli, Arnon; Remer, Lorraine A.

    1998-01-01

    Spectral remote observations of dust properties from space and from the ground creates a powerful tool for determination of dust absorption of solar radiation with an unprecedented accuracy. Absorption is a key component in understanding dust impact on climate. We use Landsat spaceborne measurements at 0.47 to 2.2 microns over Senegal with ground based sunphotometers to find that Saharan dust absorption of solar radiation is two to four times smaller than in models. Though dust absorbs in the blue, almost no absorption was found for wavelengths greater 0.6 microns. The new finding increases by 50% recent estimated solar radiative forcing by dust and decreases the estimated dust heating of the lower troposphere. Dust transported from Asia shows slightly higher absorption probably due to the presence of black carbon from populated regions. Large scale application of this method to satellite data from the Earth Observing System can reduce significantly the uncertainty in the dust radiative effects.

  3. Supersonic Mass Flux Measurements via Tunable Diode Laser Absorption and Non-Uniform Flow Modeling

    NASA Technical Reports Server (NTRS)

    Chang, Leyen S.; Strand, Christopher L.; Jeffries, Jay B.; Hanson, Ronald K.; Diskin, Glenn S.; Gaffney, Richard L.; Capriotti, Diego P.

    2011-01-01

    Measurements of mass flux are obtained in a vitiated supersonic ground test facility using a sensor based on line-of-sight (LOS) diode laser absorption of water vapor. Mass flux is determined from the product of measured velocity and density. The relative Doppler shift of an absorption transition for beams directed upstream and downstream in the flow is used to measure velocity. Temperature is determined from the ratio of absorption signals of two transitions (lambda(sub 1)=1349 nm and lambda(sub 2)=1341.5 nm) and is coupled with a facility pressure measurement to obtain density. The sensor exploits wavelength-modulation spectroscopy with second-harmonic detection (WMS-2f) for large signal-to-noise ratios and normalization with the 1f signal for rejection of non-absorption related transmission fluctuations. The sensor line-of-sight is translated both vertically and horizontally across the test section for spatially-resolved measurements. Time-resolved measurements of mass flux are used to assess the stability of flow conditions produced by the facility. Measurements of mass flux are within 1.5% of the value obtained using a facility predictive code. The distortion of the WMS lineshape caused by boundary layers along the laser line-of-sight is examined and the subsequent effect on the measured velocity is discussed. A method for correcting measured velocities for flow non-uniformities is introduced and application of this correction brings measured velocities within 4 m/s of the predicted value in a 1630 m/s flow.

  4. ABSORPTION MEASURE DISTRIBUTION IN Mrk 509

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

    Adhikari, T. P.; Różańska, A.; Sobolewska, M.

    2015-12-20

    In this paper we model the observed absorption measure distribution (AMD) in Mrk 509, which spans three orders of magnitude in ionization level with a single-zone absorber in pressure equilibrium. AMD is usually constructed from observations of narrow absorption lines in radio-quiet active galaxies with warm absorbers. We study the properties of the warm absorber in Mrk 509 using recently published broadband spectral energy distribution observed with different instruments. This spectrum is an input in radiative transfer computations with full photoionization treatment using the titan code. We show that the simplest way to fully reproduce the shape of AMD is tomore » assume that the warm absorber is a single zone under constant total pressure. With this assumption, we found theoretical AMD that matches the observed AMD determined on the basis of the 600 ks reflection grating spectrometer XMM-Newton spectrum of Mrk 509. The softness of the source spectrum and the important role of the free–free emission breaks the usual degeneracy in the ionization state calculations, and the explicit dependence of the depths of AMD dips on density open a new path to the density diagnostic for the warm absorber. In Mrk 509, the implied density is of the order of 10{sup 8} cm{sup −3}.« less

  5. A photophonic instrument concept to measure atmospheric aerosol absorption. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Engle, C. D.

    1982-01-01

    A laboratory model of an instrument to measure the absorption of atmospheric aerosols was designed, built, and tested. The design was based on the photophonic phenomenon discovered by Bell and an acoustic resonator developed by Helmholtz. Experiments were done to show ways the signal amplitude could be improved and the noise reduced and to confirm the instrument was sensitive enough to be practical. The research was undertaken to develop concepts which show promise of being improvements on the instruments that are presently used to measure the absorption of the Sun's radiation by the Earth's atmospheric aerosols.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Acetylene measurement in flames by chirp-based quantum cascade laser spectrometry.

    PubMed

    Quine, Zachary R; McNesby, Kevin L

    2009-06-01

    We have designed and characterized a mid-IR spectrometer built around a pulsed distributed-feedback quantum cascade laser using the characteristic frequency down-chirp to scan through the spectral region 6.5 cm(-1) spectral region. The behavior of this chirp is extensively measured. The accuracy and detection limits of the system as an absorption spectrometer are demonstrated first by measuring spectra of acetylene through a single pass 16 cm absorption cell in real time at low concentrations and atmospheric pressure. The smallest detectable peak is measured to be approximately 1.5 x 10(-4) absorbance units, yielding a minimum detectable concentration length product of 2.4 parts per million meter at standard temperature and pressure. This system is then used to detect acetylene within an ethylene-air opposed flow flame. Measurements of acetylene content as a function of height above the fuel source are presented, as well as measurements of acetylene produced in fuel breakdown as a function of preinjection fuel temperature.

  18. 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.

  19. Thermodynamic Activity Measurements with Knudsen Cell Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Copland, Evan H.; Jacobson, Nathan S.

    2001-01-01

    Coupling the Knudsen effusion method with mass spectrometry has proven to be one of the most useful experimental techniques for studying the equilibrium between condensed phases and complex vapors. The Knudsen effusion method involves placing a condensed sample in a Knudsen cell, a small "enclosure", that is uniformly heated and held until equilibrium is attained between the condensed and vapor phases. The vapor is continuously sampled by effusion through a small orifice in the cell. A molecular beam is formed from the effusing vapor and directed into a mass spectrometer for identification and pressure measurement of the species in the vapor phase. Knudsen cell mass spectrometry (KCMS) has been used for nearly fifty years now and continues to be a leading technique for obtaining thermodynamic data. Indeed, much of the well-established vapor specie data in the JANAF tables has been obtained from this technique. This is due to the extreme versatility of the technique. All classes of materials can be studied and all constituents of the vapor phase can be measured over a wide range of pressures (approximately 10(exp -4) to 10(exp -11) bar) and temperatures (500-2800 K). The ability to selectively measure different vapor species makes KCMS a very powerful tool for the measurement of component activities in metallic and ceramic solutions. Today several groups are applying KCMS to measure thermodynamic functions in multicomponent metallic and ceramic systems. Thermodynamic functions, especially component activities, are extremely important in the development of CALPHAD (Calculation of Phase Diagrams) type thermodynamic descriptions. These descriptions, in turn, are useful for modeling materials processing and predicting reactions such as oxide formation and fiber/matrix interactions. The leading experimental methods for measuring activities are the Galvanic cell or electro-motive force (EMF) technique and the KCMS technique. Each has specific advantages, depending on

  20. Optimal measurement counting time and statistics in gamma spectrometry analysis: The time balance

    NASA Astrophysics Data System (ADS)

    Joel, Guembou Shouop Cebastien; Penabei, Samafou; Maurice, Ndontchueng Moyo; Gregoire, Chene; Jilbert, Nguelem Mekontso Eric; Didier, Takoukam Serge; Werner, Volker; David, Strivay

    2017-01-01

    The optimal measurement counting time for gamma-ray spectrometry analysis using HPGe detectors was determined in our laboratory by comparing twelve hours measurement counting time at day and twelve hours measurement counting time at night. The day spectrum does not fully cover the night spectrum for the same sample. It is observed that the perturbation come to the sun-light. After several investigations became clearer: to remove all effects of radiation from outside (earth, the sun, and universe) our system, it is necessary to measure the background for 24, 48 or 72 hours. In the same way, the samples have to be measured for 24, 48 or 72 hours to be safe to be purified the measurement (equality of day and night measurement). It is also possible to not use the background of the winter in summer. Depend on to the energy of radionuclide we seek, it is clear that the most important steps of a gamma spectrometry measurement are the preparation of the sample and the calibration of the detector.

  1. Error Reduction Methods for Integrated-path Differential-absorption Lidar Measurements

    NASA Technical Reports Server (NTRS)

    Chen, Jeffrey R.; Numata, Kenji; Wu, Stewart T.

    2012-01-01

    We report new modeling and error reduction methods for differential-absorption optical-depth (DAOD) measurements of atmospheric constituents using direct-detection integrated-path differential-absorption lidars. Errors from laser frequency noise are quantified in terms of the line center fluctuation and spectral line shape of the laser pulses, revealing relationships verified experimentally. A significant DAOD bias is removed by introducing a correction factor. Errors from surface height and reflectance variations can be reduced to tolerable levels by incorporating altimetry knowledge and "log after averaging", or by pointing the laser and receiver to a fixed surface spot during each wavelength cycle to shorten the time of "averaging before log".

  2. 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.

  3. Measurement of beta-plus emitters by gamma-ray spectrometry.

    PubMed

    Lépy, Marie-Christine; Cassette, Philippe; Ferreux, Laurent

    2010-01-01

    The activity measurement of beta-plus emitters by gamma-ray spectrometry is studied. Experimental measurements are performed with (22)Na, (65)Zn and (64)Cu with sources included in a lead container. For these nuclides, the activity can be derived both from one photon emission peak and from the 511 keV annihilation peak, including annihilation in-flight correction and geometry correction computed by Monte Carlo simulation. The activity values obtained using the two types of peaks show satisfying agreement. The extension of the method to volume sources is discussed. Copyright 2009 Elsevier Ltd. All rights reserved.

  4. 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.

  5. Measurement of glyoxal using an incoherent broadband cavity enhanced absorption spectrometer

    NASA Astrophysics Data System (ADS)

    Washenfelder, R. A.; Langford, A. O.; Fuchs, H.; Brown, S. S.

    2008-08-01

    We describe an instrument for simultaneous measurements of glyoxal (CHOCHO) and nitrogen dioxide (NO2) using cavity enhanced absorption spectroscopy with a broadband light source. The output of a Xenon arc lamp is coupled into a 1 m optical cavity, and the spectrum of light exiting the cavity is recorded by a grating spectrometer with a charge-coupled device (CCD) array detector. The mirror reflectivity and effective path lengths are determined from the known Rayleigh scattering of He and dry zero air (N2+O2). Least-squares fitting, using published reference spectra, allow the simultaneous retrieval of CHOCHO, NO2, O4, and H2O in the 441 to 469 nm spectral range. For a 1-min sampling time, the minimum detectable absorption is 4×10-10 cm-1, and the precision (±1σ) on signal for measurements of CHOCHO and NO2 is 29 pptv and 20 pptv, respectively. We directly compare the incoherent broadband cavity enhanced absorption spectrometer to 404 and 532 nm cavity ringdown instruments for CHOCHO and NO2 detection, and find linear agreement over a wide range of concentrations. The instrument has been tested in the laboratory with both synthetic and real air samples, and the demonstrated sensitivity and specificity suggest a strong potential for field measurements of both CHOCHO and NO2.

  6. Synchrotron Photoionization Mass Spectrometry Measurements of Kinetics and Product Formation in the Allyl Radical (H2CCHCH2)Self Reaction

    NASA Technical Reports Server (NTRS)

    Selby, Talitha M.; Melini, giovanni; Goulay, Fabien; Leone, Stephen R.; Fahr, Askar; Taatjes, Craig A.; Osborn, David L.

    2008-01-01

    Product channels for the self-reaction of the resonance-stabilized allyl radical, C3H5 + C3H5, have been studied with isomeric specificity at temperatures from 300-600 K and pressures from 1-6 Torr using time-resolved multiplexed photoionization mass spectrometry. Under these conditions 1,5-hexadiene was the only C6H10 product isomer detected. The lack of isomerization of the C6H10 product is in marked contrast to the C6H6 product in the related C3H3 + C3H3 reaction, and is due to the more saturated electronic structure of the C6H10 system. The disproportionation product channel, yielding allene + propene, was also detected, with an upper limit on the branching fraction relative to recombination of 0.03. Analysis of the allyl radical decay at 298 K yielded a total rate coefficient of (2.7 +/- 0.8) x 10(exp -11) cu cm/molecule/s, in good agreement with pre.vious experimental measurements using ultraviolet kinetic absorption spectroscopy and a recent theoretical determination using variable reaction coordinate transition state theory. This result provides independent indirect support for the literature value of the allyl radical ultraviolet absorption cross-section near 223 nm.

  7. 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).

  8. 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.

  9. Nitrogen dioxide and kerosene-flame soot calibration of photoacoustic instruments for measurement of light absorption by aerosols

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

    Arnott, W. Patrick; Moosmu''ller, Hans; Walker, John W.

    2000-12-01

    A nitrogen dioxide calibration method is developed to evaluate the theoretical calibration for a photoacoustic instrument used to measure light absorption by atmospheric aerosols at a laser wavelength of 532.0 nm. This method uses high concentrations of nitrogen dioxide so that both a simple extinction and the photoacoustically obtained absorption measurement may be performed simultaneously. Since Rayleigh scattering is much less than absorption for the gas, the agreement between the extinction and absorption coefficients can be used to evaluate the theoretical calibration, so that the laser gas spectra are not needed. Photoacoustic theory is developed to account for strong absorptionmore » of the laser beam power in passage through the resonator. Findings are that the photoacoustic absorption based on heat-balance theory for the instrument compares well with absorption inferred from the extinction measurement, and that both are well within values represented by published spectra of nitrogen dioxide. Photodissociation of nitrogen dioxide limits the calibration method to wavelengths longer than 398 nm. Extinction and absorption at 532 and 1047 nm were measured for kerosene-flame soot to evaluate the calibration method, and the single scattering albedo was found to be 0.31 and 0.20 at these wavelengths, respectively.« less

  10. Measurement of the D/H, 18O/16O, and 17O/16O Isotope Ratios in Water by Laser Absorption Spectroscopy at 2.73 μm

    PubMed Central

    Wu, Tao; Chen, Weidong; Fertein, Eric; Masselin, Pascal; Gao, Xiaoming; Zhang, Weijun; Wang, Yingjian; Koeth, Johannes; Brückner, Daniela; He, Xingdao

    2014-01-01

    A compact isotope ratio laser spectrometry (IRLS) instrument was developed for simultaneous measurements of the D/H, 18O/16O and 17O/16O isotope ratios in water by laser absorption spectroscopy at 2.73 μm. Special attention is paid to the spectral data processing and implementation of a Kalman adaptive filtering to improve the measurement precision. Reduction of up to 3-fold in standard deviation in isotope ratio determination was obtained by the use of a Fourier filtering to remove undulation structure from spectrum baseline. Application of Kalman filtering enables isotope ratio measurement at 1 s time intervals with a precision (<1‰) better than that obtained by conventional 30 s averaging, while maintaining a fast system response. The implementation of the filter is described in detail and its effects on the accuracy and the precision of the isotope ratio measurements are investigated. PMID:24854363

  11. Differential Absorption Lidar (DIAL) Measurements of Landfill Methane Emissions

    NASA Astrophysics Data System (ADS)

    Innocenti, Fabrizio; Robinson, Rod; Gardiner, Tom; Finlayson, Andrew; Connor, Andy

    2017-04-01

    DIFFERENTIAL ABSORPTION LIDAR (DIAL) MEASURMENTS OF LANDFILL METHANE EMISSIONS F. INNOCENTI *, R.A. ROBINSON *, T.D. GARDINER, A. FINLAYSON *, A. CONNOR* * National Physical Laboratory (NPL), Hampton Road, Teddington, Middlesex, TW11 0LW, United Kingdom Methane is one of the most important gaseous hydrocarbon species for both industrial and environmental reasons. Understanding and quantifying methane emissions to atmosphere is an important element of climate change research. Range-resolved infrared Differential Absorption Lidar (DIAL) measurements provide the means to map and quantify a wide range of different methane sources. DIAL is a powerful technique that can be used to track and quantify plumes emitted from area emission sources such as landfill sites, waste water treatment plants and petrochemical plants. By using lidar (light detection and ranging), the DIAL technique is able to make remote range-resolved single-ended measurements of the actual distribution of target gases in the atmosphere, with no disruption to normal site operational activities. DIAL provides 3D mapping of emission concentrations and quantification of emission rates for a wide range of target gases such as methane. The NPL DIAL laser source is operated alternately at two similar wavelengths. One of these, termed the "on-resonant wavelength", is chosen to be at a wavelength which is absorbed by the target species. The other, the "off-resonant wavelength", is chosen to be at a nearby wavelength which is not absorbed significantly by the target species. The two wavelengths are chosen to be close, so that the atmospheric scattering properties are the same for both wavelengths. They are also chosen so that any differential absorption due to other atmospheric species are minimised. Any measured difference in the returned signals is therefore due to absorption by the target gas. In the typical DIAL measurement configuration the mobile DIAL facility is positioned downwind of the area being

  12. 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

  13. Simultaneous measurements of absorption spectrum and refractive index in a microfluidic system.

    PubMed

    Helseth, Lars Egil

    2012-02-13

    The characterization of dyes in various solvents requires determination of the absorption spectrum of the dye as well as the refractive index of the solvent. Typically, the refractive index of the solvent and the absorption spectrum of the solute are measured using separate experimental setups where significant liquid volumes are required. In this work the first optical measurement system that is able to do simultaneous measurements of the refractive index of the solvent and the spectral properties of the solute in a microscopic volume is presented. The laser dye Rhodamine 6G in glycerol is investigated, and the refractive index of the solution is monitored using the interference pattern of the light scattered off the channel, while its spectral properties is found by monitoring reflected light from the channel.

  14. 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.

  15. 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.

  16. Measurement of absorption and dispersion from check shot surveys

    NASA Astrophysics Data System (ADS)

    Ganley, D. C.; Kanasewich, E. R.

    1980-10-01

    The spectral ratio method for measuring absorption and also dispersion from seismic data has been examined. Corrections for frequency-dependent losses due to reflections and transmissions have been shown to be an important step in the method. Synthetic examples have been used to illustrate the method, and the method has been applied to one real data case from a sedimentary basin in the Beaufort Sea. Measured Q values were 43±2 for a depth interval of 549-1193 m and 67±6 for a depth interval of 945-1311 m. Dispersion was also measured in the data and is consistent with Futterman's model.

  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. Developments in Methods for Measuring the Intestinal Absorption of Nanoparticle-Bound Drugs

    PubMed Central

    Liu, Wei; Pan, Hao; Zhang, Caiyun; Zhao, Liling; Zhao, Ruixia; Zhu, Yongtao; Pan, Weisan

    2016-01-01

    With the rapid development of nanotechnology, novel drug delivery systems comprising orally administered nanoparticles (NPs) have been paid increasing attention in recent years. The bioavailability of orally administered drugs has significant influence on drug efficacy and therapeutic dosage, and it is therefore imperative that the intestinal absorption of oral NPs be investigated. This review examines the various literature on the oral absorption of polymeric NPs, and provides an overview of the intestinal absorption models that have been developed for the study of oral nanoparticles. Three major categories of models including a total of eight measurement methods are described in detail (in vitro: dialysis bag, rat gut sac, Ussing chamber, cell culture model; in situ: intestinal perfusion, intestinal loops, intestinal vascular cannulation; in vivo: the blood/urine drug concentration method), and the advantages and disadvantages of each method are contrasted and elucidated. In general, in vitro and in situ methods are relatively convenient but lack accuracy, while the in vivo method is troublesome but can provide a true reflection of drug absorption in vivo. This review summarizes the development of intestinal absorption experiments in recent years and provides a reference for the systematic study of the intestinal absorption of nanoparticle-bound drugs. PMID:27455239

  1. Weak absorptions in high density planetary atmospheres measured by the cavity ring down technique.

    NASA Astrophysics Data System (ADS)

    Snels, M.; Stefani, S.; Piccioni, G.

    2014-04-01

    High density planetary atmospheres are characterized by a high opacity due to the strong absorbers. Howevere usually several transparency windows exist which allow to study the lower part of the atmosphere as well as the surface emission. The weak absorptions occurring in these transparency windows are mostly due to trace species and to continuum absorption of the major absorber(s). A good example is the atmosphere of Venus, where carbondioxide causes a high opacity throughout most of the infrared wavelengths, but also has some transparency spectral windows in the near infrared, allowing the study of low lying clouds , trace species such as water vapor and in some cases the surface emission. The cavity ring down (CRD) technique has shown to be a good tool for studying weak absorptions. Here we present a CRD apparatus which can be operated at high pressures (up to 40 bar) with a sensitivity which allows to measure attenuations up to 2x10-8 cm-1. This instrument has been used to measure the carbon dioxide absorption at pressures up to 40 bar and has been also used to measure attenuation due to Rayleigh scattering at 1.18 μm.

  2. 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.

  3. Retrieval of Black Carbon Absorption from Proposed Satellite Measurements Over the Ocean Glint

    NASA Technical Reports Server (NTRS)

    Kaufman, Y. J.; Matins, J. V.; Remer, L. A.; Schoeberl, M. R.; Yamasoe, M. A.; Lau, William K. M. (Technical Monitor)

    2001-01-01

    Haze and air pollution includes many chemicals that together form small particles suspended in the air called aerosols. One of the main ingredients found to affect climate and human health is Black Carbon. Black particles emitted from engines that do not burn the fuel completely, e.g. old trucks. Black carbon absorption of sunlight emerges as one of the key components of man-made forcing of climate. However, global characterization of black carbon emissions, distribution and pathways in which it can affect the amount of solar radiation absorbed by the atmosphere is very uncertain. A new method is proposed to measure sunlight absorption by fine aerosol particles containing black carbon over the ocean glint from a satellite mission designed for this purpose. The satellite will scan the same spot over the ocean in the glint plane and a plane 40 degrees off-glint a minute apart, collecting measurements of the reflected light across the solar spectrum. First the dark ocean off the glint is used to derive aerosol properties. Then the black carbon absorption is derived prop the attenuation of the bright glint by the aerosol layer. Such measurements if realized in a proposed future mission - COBRA are expected to produce global monthly climatology of black carbon absorption with high accuracy (110 to 15%) that can show their effect on climate.

  4. 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.

  5. 236U measurement with accelerator mass spectrometry at CIAE

    NASA Astrophysics Data System (ADS)

    Wang, Xianggao; Jiang, Shan; He, Ming; Dong, Kejun; Wang, Wei; Li, Chaoli; He, Guozhu; Li, Shizhuo; Gong, Jie; Lu, Liyuan; Wu, Shaoyong

    2010-07-01

    236U is a long-lived radioactive isotope which is produced principally by thermal neutron capture on 235U. 236U may be potentially applied in geological research and nuclear safeguards. Accelerator mass spectrometry is presently the most sensitive technique for the measurement of 236U and a measurement method for long-lived heavy ion 236U has been developed. The set-up uses a dedicated injector and the newly proposed 208Pb 16O2- molecular ions for the simulation of 236U ion transport. A sensitivity of lower than 10 -10 has been achieved for the isotopic ratio 236U/ 238U in present work.

  6. Measurement and calculation of the sound absorption coefficient of pine wood charcoal

    NASA Astrophysics Data System (ADS)

    Suh, Jae Gap; Baik, Kyung min; Kim, Yong Tae; Jung, Sung Soo

    2013-10-01

    Although charcoal has been widely utilized for physical therapy and as a deodorant, water purifier, etc. due to its porous features, research on its role as a sound-absorbing material is rarely found. Thus, the sound absorption coefficients of pine wood charcoal were measured using an impedance tube and were compared with the theoretical predictions in the frequency range of 500˜ 5000 Hz. The theory developed in the current study only considers the lowest possible mode propagating along the air channels of the charcoal and shows good agreements with the measurements. As the frequency is increased, the sound absorption coefficients of pine wood charcoals also increase, but are lower than those of other commonly-used sound-absorbing materials.

  7. Aerosol absorption measurements and retrievals in shadow2 campaign

    NASA Astrophysics Data System (ADS)

    Hu, Qiaoyun; Goloub, Philippe; Podvin, Thierry; Veselovskiy, Igor; Lopatin, Anton; Dubovik, Oleg; Torres, Benjamìn; Revilini, Laura; Crumeyrolle, Suzanne; Lapionak, Tatsiana; Deroo, Christine

    2018-04-01

    Dust, maritime and dust-smoke mixture events observed during SHADOW2 (SaHAran Dust Over West Africa) field campaign are selected and analyzed by using Raman and GARRLiC retrievals. The derived aerosol optical and microphysical properties will be shown. Dust absorption profile and on ground level are derived from GARRLiC retrievals and Aethalometer measurements, respectively. Our results provide a closer insight about dust absorbing properties.

  8. The visible absorption spectrum of NO3 measured by high-resolution Fourier transform spectroscopy

    NASA Astrophysics Data System (ADS)

    Orphal, J.; Fellows, C. E.; Flaud, P.-M.

    2003-02-01

    The visible absorption spectrum of the nitrate radical NO3 has been measured using high-resolution Fourier transform spectroscopy. The spectrum was recorded at 294 K using a resolution of 0.6 cm-1 (corresponding to 0.026 nm at 662 nm) and covers the 12600-21500 cm-1 region (465-794 nm). Compared to absorption spectra of NO3 recorded previously, the new data show improvements concerning absolute wavelength calibration (uncertainty 0.02 cm-1), and spectral resolution. A new interpretation and model of the temperature dependence of the strong (0-0) band around 662 nm are proposed. The results are important for long-path tropospheric absorption measurements of NO3 and optical remote sensing of the Earth's atmosphere from space.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Evanescent Wave Absorption Based Fiber Sensor for Measuring Glucose Solution Concentration

    NASA Astrophysics Data System (ADS)

    Marzuki, Ahmad; Candra Pratiwi, Arni; Suryanti, Venty

    2018-03-01

    An optical fiber sensor based on evanescent wave absorption designed for measuring glucose solution consentration was proposed. The sensor was made to detect absorbance of various wavelength in the glucose solution. The sensing element was fabricated by side polishing of multimode polymer optical fiber to form a D-shape. The sensing element was immersed in different concentration of glucoce solution. As light propagated through the optical fiber, the evanescent wave interacted with the glucose solution. Light was absorbed by the glucose solution. The larger concentration the glucose solution has, the more the evanescent wave was absorbed in particular wavelenght. Here in this paper, light absorbtion as function of glucose concentration was measured as function of wavelength (the color of LED). We have shown that the proposed sensor can demonstrated an increase of light absorption as function of glucose concentration.

  14. Quantifying uncertainty in measurement of mercury in suspended particulate matter by cold vapor technique using atomic absorption spectrometry with hydride generator.

    PubMed

    Singh, Nahar; Ahuja, Tarushee; Ojha, Vijay Narain; Soni, Daya; Tripathy, S Swarupa; Leito, Ivo

    2013-01-01

    As a result of rapid industrialization several chemical forms of organic and inorganic mercury are constantly introduced to the environment and affect humans and animals directly. All forms of mercury have toxic effects; therefore accurate measurement of mercury is of prime importance especially in suspended particulate matter (SPM) collected through high volume sampler (HVS). In the quantification of mercury in SPM samples several steps are involved from sampling to final result. The quality, reliability and confidence level of the analyzed data depends upon the measurement uncertainty of the whole process. Evaluation of measurement uncertainty of results is one of the requirements of the standard ISO/IEC 17025:2005 (European Standard EN IS/ISO/IEC 17025:2005, issue1:1-28, 2006). In the presented study the uncertainty estimation in mercury determination in suspended particulate matter (SPM) has been carried out using cold vapor Atomic Absorption Spectrometer-Hydride Generator (AAS-HG) technique followed by wet chemical digestion process. For the calculation of uncertainty, we have considered many general potential sources of uncertainty. After the analysis of data of seven diverse sites of Delhi, it has been concluded that the mercury concentration varies from 1.59 ± 0.37 to 14.5 ± 2.9 ng/m(3) with 95% confidence level (k = 2).

  15. Method and apparatus of measuring unburned carbon in fly ash

    DOEpatents

    Brown, Robert C.

    1991-12-03

    A method and apparatus are shown to measure unburned carbon particles in the exhaust of a combustor. Photoacoustic absorption spectrometry is employed to measure the presence of the unburned carbon. Especially helpful in these measurements is a vertically elongated photoacoustic cell in which high flow velocities are maintained to prevent particles from settling. These measurements are useful in determining the efficiency of coal-fired combustors.

  16. 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.

  17. 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%.

  18. Continuous high-frequency dissolved O2/Ar measurements by equilibrator inlet mass spectrometry.

    PubMed

    Cassar, Nicolas; Barnett, Bruce A; Bender, Michael L; Kaiser, Jan; Hamme, Roberta C; Tilbrook, Bronte

    2009-03-01

    The oxygen (O(2)) concentration in the surface ocean is influenced by biological and physical processes. With concurrent measurements of argon (Ar), which has similar solubility properties as oxygen, we can remove the physical contribution to O(2) supersaturation and determine the biological oxygen supersaturation. Biological O(2) supersaturation in the surface ocean reflects the net metabolic balance between photosynthesis and respiration, i.e., the net community productivity (NCP). We present a new method for continuous shipboard measurements of O(2)/Ar by equilibrator inlet mass spectrometry (EIMS). From these measurements and an appropriate gas exchange parametrization, NCP can be estimated at high spatial and temporal resolution. In the EIMS configuration, seawater from the ship's continuous intake flows through a cartridge enclosing a gas-permeable microporous membrane contactor. Gases in the headspace of the cartridge equilibrate with dissolved gases in the flowing seawater. A fused-silica capillary continuously samples headspace gases, and the O(2)/Ar ratio is measured by mass spectrometry. The ion current measurements on the mass spectrometer reflect the partial pressures of dissolved gases in the water flowing through the equilibrator. Calibration of the O(2)/Ar ion current ratio (32/40) is performed automatically every 2 h by sampling ambient air through a second capillary. A conceptual model demonstrates that the ratio of gases reaching the mass spectrometer is dependent on several parameters, such as the differences in molecular diffusivities and solubilities of the gases. Laboratory experiments and field observations performed by EIMS are discussed. We also present preliminary evidence that other gas measurements, such as N(2)/Ar and pCO(2) measurements, may potentially be performed with EIMS. Finally, we compare the characteristics of the EIMS with the previously described membrane inlet mass spectrometry (MIMS) approach.

  19. 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.

  20. Absorption of Solar Radiation by the Cloudy Atmosphere: Further Interpretations of Collocated Aircraft Measurements

    NASA Technical Reports Server (NTRS)

    Cess, R. D.; Zhang, Minghua; Valero, Francisco P. J.; Pope, Shelly K.; Bucholtz, Anthony; Bush, Brett; Zender, Charles S.

    1998-01-01

    We have extended the interpretations made in two prior studies of the aircraft shortwave radiation measurements that were obtained as part of the Atmospheric Radiation Measurements (ARM) Enhanced Shortwave Experiments (ARESE). These extended interpretations use the 500 nm (10 nm bandwidth) measurements to minimize sampling errors in the broadband measurements. It is indicated that the clouds present during this experiment absorb more shortwave radiation than predicted by clear skies and thus by theoretical models, that at least some (less than or equal to 20%) of this enhanced cloud absorption occurs at wavelengths less than 680 nm, and that the observed cloud absorption does not appear to be an artifact of sampling errors nor of instrument calibration errors.

  1. Measurements of K shell absorption jump factors and jump ratios using EDXRF technique

    NASA Astrophysics Data System (ADS)

    Kacal, Mustafa Recep; Han, İbrahim; Akman, Ferdi

    2015-04-01

    In the present work, the K-shell absorption jump factors and jump ratios for 30 elements between Ti ( Z = 22) and Er ( Z = 68) were measured by energy dispersive X-ray fluorescence (EDXRF) technique. The jump factors and jump ratios for these elements were determined by measuring the K shell fluorescence parameters such as the Kα X-ray production cross-sections, K shell fluorescence yields, Kβ-to- Kα X-rays intensity ratios, total atomic absorption cross sections and mass attenuation coefficients. The measurements were performed using an Am-241 radioactive point source and a Si (Li) detector in direct excitation and transmission experimental geometry. The results for jump factors and jump ratios were compared with theoretically calculated and the ones available in the literature.

  2. 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

  3. Measuring Thermodynamic Properties of Metals and Alloys With Knudsen Effusion Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Copland, Evan H.; Jacobson, Nathan S.

    2010-01-01

    This report reviews Knudsen effusion mass spectrometry (KEMS) as it relates to thermodynamic measurements of metals and alloys. First, general aspects are reviewed, with emphasis on the Knudsen-cell vapor source and molecular beam formation, and mass spectrometry issues germane to this type of instrument are discussed briefly. The relationship between the vapor pressure inside the effusion cell and the measured ion intensity is the key to KEMS and is derived in detail. Then common methods used to determine thermodynamic quantities with KEMS are discussed. Enthalpies of vaporization, the fundamental measurement, are determined from the variation of relative partial pressure with temperature using the second-law method or by calculating a free energy of formation and subtracting the entropy contribution using the third-law method. For single-cell KEMS instruments, measurements can be used to determine the partial Gibbs free energy if the sensitivity factor remains constant over multiple experiments. The ion-current ratio method and dimer-monomer method are also viable in some systems. For a multiple-cell KEMS instrument, activities are obtained by direct comparison with a suitable component reference state or a secondary standard. Internal checks for correct instrument operation and general procedural guidelines also are discussed. Finally, general comments are made about future directions in measuring alloy thermodynamics with KEMS.

  4. Cavity-enhanced measurements of hydrogen peroxide absorption cross sections from 353 to 410 nm.

    PubMed

    Kahan, Tara F; Washenfelder, Rebecca A; Vaida, Veronica; Brown, Steven S

    2012-06-21

    We report near-ultraviolet and visible absorption cross sections of hydrogen peroxide (H(2)O(2)) using incoherent broad-band cavity-enhanced absorption spectroscopy (IBBCEAS), a recently developed, high-sensitivity technique. The measurements reported here span the range of 353-410 nm and extend published electronic absorption cross sections by 60 nm to absorption cross sections below 1 × 10(-23) cm(2) molecule(-1). We have calculated photolysis rate constants for H(2)O(2) in the lower troposphere at a range of solar zenith angles by combining the new measurements with previously reported data at wavelengths shorter than 350 nm. We predict that photolysis at wavelengths longer than those included in the current JPL recommendation may account for up to 28% of the total hydroxyl radical (OH) production from H(2)O(2) photolysis under some conditions. Loss of H(2)O(2) via photolysis may be of the same order of magnitude as reaction with OH and dry deposition in the lower atmosphere; these processes have very different impacts on HO(x) loss and regeneration.

  5. Simultaneous measurement of displacement current and absorption spectra of Langmuir film

    NASA Astrophysics Data System (ADS)

    Xu, Xiaobin; Kubota, Tohru; Iwamoto, Mitsumasa

    1995-07-01

    A Maxwell-displacement-current measuring system coupled with the system used for the measurement of absorption spectra of monolayers on a water surface has been developed. Using this system, the displacement current and the absorbance across monolayers of squarylium dye at the air/water surface were detected. It was found that the change in J aggregate in the monolayers with monolayer compression was detectable using the system.

  6. Measurement of He neutral temperature in detached plasmas using laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Aramaki, M.; Tsujihara, T.; Kajita, S.; Tanaka, H.; Ohno, N.

    2018-01-01

    The reduction of the heat load onto plasma-facing components by plasma detachment is an inevitable scheme in future nuclear fusion reactors. Since the control of the plasma and neutral temperatures is a key issue to the detached plasma generation, we have developed a laser absorption spectroscopy system for the metastable helium temperature measurements and used together with a previously developed laser Thomson scattering system for the electron temperature and density measurements. The thermal relaxation process between the neutral and the electron in the detached plasma generated in the linear plasma device, NAGDIS-II was studied. It is shown that the electron temperature gets close to the neutral temperature by increasing the electron density. On the other hand, the pressure dependence of electron and neutral temperatures shows the cooling effect by the neutrals. The possibility of the plasma fluctuation measurement using the fluctuation in the absorption signal is also shown.

  7. Thermal neutron macroscopic absorption cross section measurement (theory, experiment and results) for small environmental samples

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

    Czubek, J.A.; Drozdowicz, K.; Gabanska, B.

    Czubek`s method of measurement of the thermal neutron macroscopic absorption cross section of small samples has been developed at the Henryk Niewodniczanski Institute of Nuclear Physics in Krakow, Poland. Theoretical principles of the method have been elaborated in the one-velocity diffusion approach in which the thermal neutron parameters used have been averaged over a modified Maxwellian. In consecutive measurements the investigated sample is enveloped in shells of a known moderator of varying thickness and irradiated with a pulsed beam of fast neutrons. The neutrons are slowed-down in the system and a die-away rate of escaping thermal neutrons is measured. Themore » decay constant vs. thickness of the moderator creates the experimental curve. The absorption cross section of the unknown sample is found from the intersection of this curve with the theoretical one. The theoretical curve is calculated for the case when the dynamic material buckling of the inner sample is zero. The method does not use any reference absorption standard and is independent of the transport cross section of the measured sample. The volume of the sample is form of fluid or crushed material is about 170 cm{sup 3}. The standard deviation for the measured mass absorption cross section of rock samples is in the range of 4 divided by 20% of the measured value and for brines is of the order of 0.5%.« less

  8. Twin Knudsen Cell Configuration for Activity Measurements by Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Jacobson, N. S.

    1996-01-01

    A twin Knudsen cell apparatus for alloy activity measurements by mass spectrometry is described. Two Knudsen cells - one containing an alloy and one containing a pure component - are mounted on a single flange and translated into the sampling region via a motorized x-y table. Mixing of the molecular beams from the cells is minimized by a novel system of shutters. Activity measurements were taken on two well-characterized alloys to verify the operation of the system. Silver activity measurements are reported for Ag-Cu alloys and aluminum activity measurements are reported for Fe-Al alloys. The temperature dependence of activity for a 0.474 mol fraction Al-Fe alloy gives a partial molar heat of aluminum. Measurements taken with the twin cell show good agreement with literature values for these alloys.

  9. Absorption spectroscopy of microalgae, cyanobacteria, and dissolved organic matter: Measurements in an integrating sphere cavity

    NASA Astrophysics Data System (ADS)

    Pogosyan, S. I.; Durgaryan, A. M.; Konyukhov, I. V.; Chivkunova, O. B.; Merzlyak, M. N.

    2009-12-01

    A device for integrating cavity absorption measurements (ICAM) with an internal diameter of 80 mm suitable for field research is described. The spectral features of the light absorption by some cyanobacteria, green algae, and diatoms in the integrating sphere were studied and the dependences of the absorption on the cell concentration were determined in comparison with the conventional measurements in a 1-cm cuvette. The sensitivity of the chlorophyll estimation with the ICAM reached 0.2-0.5 mg m-3. The results of the ICAM application for the direct analysis of the natural phytoplankton and dissolved organic (“yellow“) matter in the Black Sea and the Sea of Japan are described.

  10. Atmospheric Measurements by Cavity Enhanced Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Yi, Hongming; Wu, Tao; Coeur-Tourneur, Cécile; Fertein, Eric; Gao, Xiaoming; Zhao, Weixiong; Zhang, Weijun; Chen, Weidong

    2015-04-01

    Since the last decade, atmospheric environmental monitoring has benefited from the development of novel spectroscopic measurement techniques owing to the significant breakthroughs in photonic technology from the UV to the infrared spectral domain [1]. In this presentation, we will overview our recent development and applications of cavity enhanced absorption spectroscopy techniques for in situ optical monitoring of chemically reactive atmospheric species (such as HONO, NO3, NO2, N2O5) in intensive campaigns [2] and/or in smog chamber studies [3]. These field deployments demonstrated that modern photonic technologies (newly emergent light sources combined with high sensitivity spectroscopic techniques) can provide a useful tool to improve our understanding of tropospheric chemical processes which affect climate, air quality, and the spread of pollution. Experimental detail and preliminary results will be presented. Acknowledgements. The financial support from the French Agence Nationale de la Recherche (ANR) under the NexCILAS (ANR-11-NS09-0002) and the CaPPA (ANR-10-LABX-005) contracts is acknowledged. References [1] X. Cui, C. Lengignon, T. Wu, W. Zhao, G. Wysocki, E. Fertein, C. Coeur, A. Cassez,L. Croisé, W. Chen, et al., "Photonic Sensing of the Atmosphere by absorption spectroscopy", J. Quant. Spectrosc. Rad. Transfer 113 (2012) 1300-1316 [2] T. Wu, Q. Zha, W. Chen, Z. XU, T. Wang, X. He, "Development and deployment of a cavity enhanced UV-LED spectrometer for measurements of atmospheric HONO and NO2 in Hong Kong", Atmos. Environ. 95 (2014) 544-551 [3] T. Wu, C. Coeur-Tourneur, G. Dhont,A. Cassez, E. Fertein, X. He, W. Chen,"Application of IBBCEAS to kinetic study of NO3 radical formation from O3 + NO2 reaction in an atmospheric simulation chamber", J. Quant. Spectrosc. Rad. Transfer 133 (2014)199-205

  11. A Near-Infrared Spectrometer to Measure Zodiacal Light Absorption Spectrum

    NASA Technical Reports Server (NTRS)

    Kutyrev, A. S.; Arendt, R.; Dwek, E.; Kimble, R.; Moseley, S. H.; Rapchun, D.; Silverberg, R. F.

    2010-01-01

    We have developed a high throughput infrared spectrometer for zodiacal light fraunhofer lines measurements. The instrument is based on a cryogenic dual silicon Fabry-Perot etalon which is designed to achieve high signal to noise Fraunhofer line profile measurements. Very large aperture silicon Fabry-Perot etalons and fast camera optics make these measurements possible. The results of the absorption line profile measurements will provide a model free measure of the zodiacal Light intensity in the near infrared. The knowledge of the zodiacal light brightness is crucial for accurate subtraction of zodiacal light foreground for accurate measure of the extragalactic background light after the subtraction of zodiacal light foreground. We present the final design of the instrument and the first results of its performance.

  12. Temperature sensitivity of differential absorption lidar measurements of water vapor in the 720-nm region

    NASA Technical Reports Server (NTRS)

    Browell, Edward V.; Ismail, Syed; Grossmann, Benoist E.

    1991-01-01

    Recently measured properties of water vapor (H2O) absorption lines have been used in calculations to evalute the temperature sensitivity of differential absorption lidar (Dial) H2O measurements. This paper estimates the temperature sensitivity of H2O lines in the 717-733-nm region for both H2O mixing ratio and number density measurements, and discusses the influence of the H2O line ground state energies E-double-prime, the H2O absorption linewidths, the linewidth temperature dependence parameter, and the atmospheric temperature and pressure variations with altitude and location on the temperature sensitivity calculations. Line parameters and temperature sensitivity calculations for 67 H2O lines in the 720-nm band are given which can be directly used in field experiments. Water vapor lines with E-double-prime values in the 100-300/cm range were found to be optimum for Dial measurements of H2O number densities, while E-double-prime values in the 250-500/cm range were found to be optimum for H2O mixing ratio measurements.

  13. 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.

  14. Measurement of total-body cobalt-57 vitamin B12 absorption with a gamma camera.

    PubMed

    Cardarelli, J A; Slingerland, D W; Burrows, B A; Miller, A

    1985-08-01

    Previously described techniques for the measurement of the absorption of [57Co]vitamin B12 by total-body counting have required an iron room equipped with scanning or multiple detectors. The present study uses simplifying modifications which make the technique more available and include the use of static geometry, the measurement of body thickness to correct for attenuation, a simple formula to convert the capsule-in-air count to a 100% absorption count, and finally the use of an adequately shielded gamma camera obviating the need of an iron room.

  15. 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.

  16. 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

  17. 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

  18. [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.

  19. 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

  20. 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.

  1. 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.

  2. Measuring the radium quartet (228Ra, 226Ra, 224Ra, 223Ra) in seawater samples using gamma spectrometry.

    PubMed

    van Beek, P; Souhaut, M; Reyss, J-L

    2010-07-01

    Radium isotopes are widely used in marine studies (eg. to trace water masses, to quantify mixing processes or to study submarine groundwater discharge). While 228Ra and 226Ra are usually measured using gamma spectrometry, short-lived Ra isotopes (224Ra and 223Ra) are usually measured using a Radium Delayed Coincidence Counter (RaDeCC). Here we show that the four radium isotopes can be analyzed using gamma spectrometry. We report 226Ra, 228Ra, 224Ra, 223Ra activities measured using low-background gamma spectrometry in standard samples, in water samples collected in the vicinity of our laboratory (La Palme and Vaccarès lagoons, France) but also in seawater samples collected in the plume of the Amazon river, off French Guyana (AMANDES project). The 223Ra and 224Ra activities determined in these samples using gamma spectrometry were compared to the activities determined using RaDeCC. Activities determined using the two techniques are in good agreement. Uncertainties associated with the 224Ra activities are similar for the two techniques. RaDeCC is more sensitive for the detection of low 223Ra activities. Gamma spectrometry thus constitutes an alternate method for the determination of short-lived Ra isotopes. 2009 Elsevier Ltd. All rights reserved.

  3. 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.

  4. 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

  5. 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.

  6. Method and apparatus for measuring butterfat and protein content using microwave absorption techniques

    DOEpatents

    Fryer, Michael O.; Hills, Andrea J.; Morrison, John L.

    2000-01-01

    A self calibrating method and apparatus for measuring butterfat and protein content based on measuring the microwave absorption of a sample of milk at several microwave frequencies. A microwave energy source injects microwave energy into the resonant cavity for absorption and reflection by the sample undergoing evaluation. A sample tube is centrally located in the resonant cavity passing therethrough and exposing the sample to the microwave energy. A portion of the energy is absorbed by the sample while another portion of the microwave energy is reflected back to an evaluation device such as a network analyzer. The frequency at which the reflected radiation is at a minimum within the cavity is combined with the scatter coefficient S.sub.11 as well as a phase change to calculate the butterfat content in the sample. The protein located within the sample may also be calculated in a likewise manner using the frequency, S.sub.11 and phase variables. A differential technique using a second resonant cavity containing a reference standard as a sample will normalize the measurements from the unknown sample and thus be self-calibrating. A shuttered mechanism will switch the microwave excitation between the unknown and the reference cavities. An integrated apparatus for measuring the butterfat content in milk using microwave absorption techniques is also presented.

  7. Staying Alive: Measuring Intact Viable Microbes with Electrospray Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Forsberg, Erica; Fang, Mingliang; Siuzdak, Gary

    2017-01-01

    Mass spectrometry has traditionally been the technology of choice for small molecule analysis, making significant inroads into metabolism, clinical diagnostics, and pharmacodynamics since the 1960s. In the mid-1980s, with the discovery of electrospray ionization (ESI) for biomolecule analysis, a new door opened for applications beyond small molecules. Initially, proteins were widely examined, followed by oligonucleotides and other nonvolatile molecules. Then in 1991, three intriguing studies reported using mass spectrometry to examine noncovalent protein complexes, results that have been expanded on for the last 25 years. Those experiments also raised the questions: How soft is ESI, and can it be used to examine even more complex interactions? Our lab addressed these questions with the analyses of viruses, which were initially tested for viability following electrospray ionization and their passage through a quadrupole mass analyzer by placing them on an active medium that would allow them to propagate. This observation has been replicated on multiple different systems, including experiments on an even bigger microbe, a spore. The question of analysis was also addressed in the early 2000s with charge detection mass spectrometry. This unique technology could simultaneously measure mass-to-charge and charge, allowing for the direct determination of the mass of a virus. More recent experiments on spores and enveloped viruses have given us insight into the range of mass spectrometry's capabilities (reaching 100 trillion Da), beginning to answer fundamental questions regarding the complexity of these organisms beyond proteins and genes, and how small molecules are integral to these supramolecular living structures.

  8. 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.

  9. Photoacoustic and filter measurements related to aerosol light absorption during the Northern Front Range Air Quality Study (Colorado 1996/1997)

    NASA Astrophysics Data System (ADS)

    Moosmüller, H.; Arnott, W. P.; Rogers, C. F.; Chow, J. C.; Frazier, C. A.; Sherman, L. E.; Dietrich, D. L.

    1998-11-01

    A new photoacoustic instrument for the measurement of aerosol light absorption was collocated with conventional aerosol instrumentation during the 1996-1997 winter intensive monitoring period of the Northern Front Range Air Quality Study. Measurements of the light absorption efficiency for black carbon were 5 m2/g at 685 nm and 10 m2/g at 532 nm, and for elemental carbon, they were 3.6 m2/g at 685 nm. We show that these values together with previous photoacoustic measurements of aerosol light absorption shed some light on the wavelength dependence of absorption efficiency for carbonaceous aerosol in the visible and near-visible region. Integrating plate type filter measurements of aerosol light absorption result in far larger values than those measured with the photoacoustic instrument. We demonstrate that a recently published correction technique [Horvath, 1997] can yield improved agreement.

  10. [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

  11. Atmospheric absorption measurements in the region of 1 mm wavelength.

    NASA Technical Reports Server (NTRS)

    Emery, R.

    1972-01-01

    A Froome-type plasma-metal-junction device (1962) was used in high-resolution radiation transmission measurements in the atmosphere at wavelengths from 0.5 to 3.0 mm. The experimental and theoretical results for water vapor absorption lines in two submillimeter wavelength windows were compared, showing that this technique provided a much higher wavelength accuracy than more conventional optical-type spectroscopy.

  12. A pilot study: subclinical hypothyroidism and free thyroid hormone measurement by immunoassay and mass spectrometry.

    PubMed

    Gounden, Verena; Jonklaas, Jacqueline; Soldin, Steven J

    2014-03-20

    The diagnosis of subclinical hypothyroidism is defined as the presence of an elevated thyroid stimulating hormone (TSH) with a normal free thyroxine (FT4) level. The commonly used direct analogue immunoassays for the measurement of FT4 have been shown to have poor performance at the upper and lower limits of the FT4 reference interval. The purpose of this pilot study was to investigate the percentage of individuals classified as having subclinical hypothyroidism with a standard immunoassay, that actually have low free thyroid hormone levels by mass spectrometry measurements. Outpatient samples with elevated TSH values and normal FT4 concentrations as per standard immunoassay methods were collected. FT4 and free triiodothyronine (FT3) analyses were performed on these samples using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Sixty five percent (n=26) of patients (n=40) had (LC-MS/MS) FT4 or FT3 or both FT4 and FT3 values below mass spectrometry reference limits. Our findings indicate that the direct analogue immunoassay method for FT4 measurement results in a significant proportion of patients being misclassified as having subclinical hypothyroidism. Published by Elsevier B.V.

  13. Optoacoustic measurements of water vapor absorption at selected CO laser wavelengths in the 5-micron region

    NASA Technical Reports Server (NTRS)

    Menzies, R. T.; Shumate, M. S.

    1976-01-01

    Measurements of water vapor absorption were taken with a resonant optoacoustical detector (cylindrical pyrex detector, two BaF2 windows fitted into end plates at slight tilt to suppress Fabry-Perot resonances), for lack of confidence in existing spectral tabular data for the 5-7 micron region, as line shapes in the wing regions of water vapor lines are difficult to characterize. The measurements are required for air pollution studies using a CO laser, to find the differential absorption at the wavelengths in question due to atmospheric constituents other than water vapor. The design and performance of the optoacoustical detector are presented. Effects of absorption by ambient NO are considered, and the fixed-frequency discretely tunable CO laser is found suitable for monitoring urban NO concentrations in a fairly dry climate, using the water vapor absorption data obtained in the study.

  14. 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.

  15. Density Measurement for MORB Melts by X-ray Absorption Method

    NASA Astrophysics Data System (ADS)

    Sakamaki, T.; Urakawa, S.; Suzuki, A.; Ohtani, E.; Katayama, Y.

    2006-12-01

    Density of silicate melts at high pressure is one of the most important properties to understand magma migration in the planetary interior and the differentiation of the terrestrial planets. The density measurements of silicate melts have been carried out by several methods (shock compression experiments and sink-float method in static experiments, etc.). However, since these methods have difficulties in acquisition of data at a desired pressure and temperature, the density of the silicate melt have been measured under only a few conditions. Recently a new density measurement was developed by the X-ray absorption method. Advantage of this method is to measure density of liquids at a desired pressure and temperature. In the present study we measured the density of MORB melt by X-ray absorption method. Experiments were carried out at the BL22XU beamline at SPring-8. A DIA-type cubic anvil apparatus was used for generation of high pressure and temperature. We used tungsten carbide anvils with the top anvil sizes of 6 mm and 4 mm. The energy of monochromateized X-ray beam was 23 keV. The intensities of incident and transmitted X-ray were measured by ion chambers. The density of the melt was calculated on the basis of Beer-Lambert law. The starting material was a glass with the MORB composition. Experiments were made from 1 atm to 5 GPa, from 300 to 2000 K. We compared the density of MORB melt with the compression curve of the melt in previous works. The density measured by this study is lower than that expected from the compression curve determined at higher pressures by the sink-float method. Structural change of the MORB melt with increasing pressure might be attributed to this discrepancy.

  16. Density Measurement for MORB Melts by X-ray Absorption Method

    NASA Astrophysics Data System (ADS)

    Sakamaki, T.; Urakawa, S.; Ohtani, E.; Suzuki, A.; Katayama, Y.

    2005-12-01

    Density of silicate melts at high pressure is one of the most important properties to understand magma migration in the planetary interior and the differentiation of the terrestrial planets. The density measurements of silicate melts have been carried out by several methods (shock compression experiments and sink-float method in static experiments, etc.). However, since these methods have difficulties in acquisition of data at a desired pressure and temperature, the density of the silicate melt have been measured under only a few conditions. Recently a new density measurement was developed by the X-ray absorption method. Advantage of this method is to measure density of liquids at a desired pressure and temperature. In the present study we measured the density of MORB melt by X-ray absorption method. Experiments were carried out at the BL22XU beamline at SPring-8. A DIA-type cubic anvil apparatus was used for generation of high pressure and temperature. We used tungsten carbide anvils with the edge-length of 6 mm. The energy of monochromateized X-ray beam was 23 keV. The intensities of incident and transmitted X-ray were measured by ion chambers. The density of the melt was calculated on the basis of Beer-Lambert law. The starting material was a glass with the MORB composition. Experiments were made from 1 atm to 4 GPa, from 300 to 2200 K. We compared the density of MORB melt with the compression curve of the melt in previous works. The density measured by this study is lower than that expected from the compression curve determined at higher pressures by the sink-float method. Structural change of the MORB melt with increasing pressure might be attributed to this discrepancy.

  17. MULTI-POLLUTANT CONCENTRATION MEASUREMENTS AROUND A CONCENTRATED SWINE PRODUCTION FACILITY USING OPEN-PATH FTIR SPECTROMETRY

    EPA Science Inventory

    Open-path Fourier transform infrared (OP/FTIR) spectrometry was used to measure the concentrations of ammonia, methane, and other atmospheric gasses around an integrated industrial swine production facility in eastern North Carolina. Several single-path measurements were made ove...

  18. Quantitative Measurement of Local Infrared Absorption and Dielectric Function with Tip-Enhanced Near-Field Microscopy.

    PubMed

    Govyadinov, Alexander A; Amenabar, Iban; Huth, Florian; Carney, P Scott; Hillenbrand, Rainer

    2013-05-02

    Scattering-type scanning near-field optical microscopy (s-SNOM) and Fourier transform infrared nanospectroscopy (nano-FTIR) are emerging tools for nanoscale chemical material identification. Here, we push s-SNOM and nano-FTIR one important step further by enabling them to quantitatively measure local dielectric constants and infrared absorption. Our technique is based on an analytical model, which allows for a simple inversion of the near-field scattering problem. It yields the dielectric permittivity and absorption of samples with 2 orders of magnitude improved spatial resolution compared to far-field measurements and is applicable to a large class of samples including polymers and biological matter. We verify the capabilities by determining the local dielectric permittivity of a PMMA film from nano-FTIR measurements, which is in excellent agreement with far-field ellipsometric data. We further obtain local infrared absorption spectra with unprecedented accuracy in peak position and shape, which is the key to quantitative chemometrics on the nanometer scale.

  19. NO2 trace measurements by optical-feedback cavity-enhanced absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Ventrillard-Courtillot, I.; Foldes, T.; Romanini, D.

    2009-04-01

    In order to reach the sub-ppb NO2 detection level required for environmental applications in remote areas, we are developing a spectrometer that exploits a technique that we introduced several years ago, named Optical-Feedback Cavity-Enhanced Absorption Spectroscopy (OF-CEAS) [1]. It allows very sensitive and selective measurements, together with the realization of compact and robust set-ups as was subsequently demonstrated during measurements campaigns in harsh environments [2,3]. OF-CEAS benefits from the optical feedback (OF) to efficiently inject a cw-laser in a high finesse cavity (typically F >10 000). Absorption spectra are acquired on a small spectral region (~1 cm-1) that enables selective and quantitative measurements at a fast acquisition rate (~10 Hz) with a detection limit of several 10-10 cm-1 as reported in this paper. Spectra are obtained with high spectral resolution (~150 MHz) and are self calibrated by cavity rind-down measurements regularly performed (typically every second). Therefore, OF-CEAS appears very attractive for NO2 trace detection. This work is performed in the blue spectral region where NO2 has intense electronic transitions. Our setup involves a commercial extended cavity diode laser (ECDL) working at room temperature around 411nm. A first setup was developed [4] to demonstrate that OF sensitivity of ECDL is fully consistent with this technique, initially introduced with distributed feedback diode lasers in the near infrared region. In this paper we will report on a new set-up developed for in-situ measurements with proper mechanical, acoustic and thermal insulation. Additionally, new data processing was implemented allowing real time concentration measurements. It is based on a reference spectra recorded under controlled conditions by OF-CEAS and used later to fit the observed spectra. We will present measurements performed with calibrated NO2 reference samples demonstrating a good linearity of the apparatus. The minimum detectable

  20. 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.

  1. Absorption of Solar Radiation by Clouds: A Second Look at Irradiance Measurements

    NASA Technical Reports Server (NTRS)

    Tsay, Si-Chee; King, Michael D.; Cahalan, Robert F.; Lau, William K.-M. (Technical Monitor)

    2001-01-01

    A decade ago, Stephens and Tsay provided an overview of the subject of absorption of solar radiation by clouds in the earth's atmosphere. They summarized the available evidence that pointed to disagreements between theoretical and observed values of cloud absorption (and reflection). At that time, a theoretician's approach (assuming perfect flux measurements) was adopted to test the model uncertainty under various hypotheses, such as the omitted large drops, excess absorbing aerosols, enhanced water vapor continuum absorption, and cloud inhomogeneity. Since then, several advances in theoretical work have been made, but a satisfactory answer for the discrepancy is still lacking. Now, we offer an experimentalist's approach (focusing on field, not laboratory) to examine the observational uncertainty under numerous field factors, such as the temperature dependence, attitude control, and sampling strategy in the spatial and spectral domain. Examples from recent field campaigns have pointed out that these sources of error may be responsible for the unacceptable level of uncertainty (e.g., as large as 20 W/square m). We give examples of each, discuss their contribution to overall uncertainty in shortwave absorption, and suggest a coordinated approach to their solution.

  2. Measurement of diffusion coefficients important in modeling the absorption rate of carbon dioxide into aqueous N-methyldiethanolamine

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

    Rowley, R.L.; Adams, M.E.; Marshall, T.L.

    1997-03-01

    Natural gas processors use amine treating processes to remove the acid gases H{sub 2}S and CO{sub 2} from gas streams. Absorption rates of gaseous CO{sub 2} into aqueous N-methyldiethanolamine (MDEA) solutions were measured in a quiescent, inverted-tube diffusiometer by monitoring the rate of pressure drop. The absorption rate was found to be insensitive to the diffusion coefficient of CO{sub 2} in solution but very sensitive to the diffusion rate of bicarbonate and protonated MDEA ions. Evidence also suggested that chemical reaction equilibrium is rapid relative to diffusion. A numerical model was developed on the basis of these observations. The modelmore » was used to regress diffusion coefficients of bicarbonate and protonated amine, which must be equivalent by electroneutrality arguments, from measured absorption rates. Complete modeling of the absorption process also required data for the diffusion coefficient of MDEA in water. These were measured using a Taylor dispersion apparatus. CO{sub 2} absorption rates and diffusion coefficients of bicarbonate and protonated MDEA were obtained at 298.2 K and 318.2 K in solutions containing 20, 35, and 50 mass % MDEA in water.« less

  3. Measurements of 59Ni in meteorites by accelerator mass spectrometry

    NASA Astrophysics Data System (ADS)

    Paul, M.; Fifield, L. K.; Fink, D.; Albrecht, A.; Allan, G. L.; Herzog, G.; Tuniz, C.

    1993-10-01

    Isotopic abundances of the radionuclide 59Ni (T1/2 = 76000 yr) were measured by accelerator mass spectrometry with the 14UD Pelletron tandem accelerator at the Australian National University and a detection system solely based on a multianode ionization chamber. The sensitivity limit in the measurement of 59Ni isotopic abundances is 5 × 10-13, as determined by residual interferences from isobaric 59Co and isotopic 58Ni ions. Cosmogenic 59Ni abundances 59Ni/Ni = (8-20) × 10-12 were measured in four samples prepared from the metal phase of two meteorites (mesosiderites). The ratio of the 59Ni abundances to those measured for 41Ca in the silicate phase of the same samples, is in fair agreement with the ratio of the production rates via thermal-neutron capture on 58Ni and 40Ca.

  4. Measurement of glyoxal using an incoherent broadband cavity enhanced absorption spectrometer

    NASA Astrophysics Data System (ADS)

    Washenfelder, R. A.; Langford, A. O.; Fuchs, H.; Brown, S. S.

    2008-12-01

    We describe an instrument for simultaneous measurements of glyoxal (CHOCHO) and nitrogen dioxide (NO2) using cavity enhanced absorption spectroscopy with a broadband light source. The output of a Xenon arc lamp is coupled into a 1 m optical cavity, and the spectrum of light exiting the cavity is recorded by a grating spectrometer with a charge-coupled device (CCD) array detector. The mirror reflectivity and effective path lengths are determined from the known Rayleigh scattering of He and dry zero air (N2+O2). Least-squares fitting, using published reference spectra, allow the simultaneous retrieval of CHOCHO, NO2, O4, and H2O in the 441 to 469 nm spectral range. For a 1-min sampling time, the precision (±1σ) on signal for measurements of CHOCHO and NO2 is 29 pptv and 20 pptv, respectively. We directly compare measurements made with the incoherent broadband cavity enhanced absorption spectrometer with those from cavity ringdown instruments detecting CHOCHO and NO2 at 404 and 532 nm, respectively, and find linear agreement over a wide range of concentrations. The instrument has been tested in the laboratory with both synthetic and real air samples, and the demonstrated sensitivity and specificity suggest a strong potential for field measurements of both CHOCHO and NO2.

  5. Transient Infrared Measurement of Laser Absorption Properties of Porous Materials

    NASA Astrophysics Data System (ADS)

    Marynowicz, Andrzej

    2016-06-01

    The infrared thermography measurements of porous building materials have become more frequent in recent years. Many accompanying techniques for the thermal field generation have been developed, including one based on laser radiation. This work presents a simple optimization technique for estimation of the laser beam absorption for selected porous building materials, namely clinker brick and cement mortar. The transient temperature measurements were performed with the use of infrared camera during laser-induced heating-up of the samples' surfaces. As the results, the absorbed fractions of the incident laser beam together with its shape parameter are reported.

  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. 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

  8. Design And Construction of an Impedance Tube for Measuring Sound Absorptivity and Transmissibility of Materials Using Transfer Function Method

    NASA Astrophysics Data System (ADS)

    Gowda, Haarish Kapaninaikappa

    Noise is defined as unwanted sound, when perceived in excess can cause many harmful effects such as annoyance, interference with speech, and hearing loss, hence there is a need to control noise in practical situations. Noise can be controlled actively and/or passively, here we discuss the passive noise control techniques. Passive noise control involves using energy dissipating or reflecting materials such as absorbers or barriers respectively. Damping and isolating materials are also used in eliminating structure-borne noise. These materials exhibit properties such as reflection, absorption and transmission loss when incidence is by a sound source. Thus, there is a need to characterize the acoustical properties of these materials for practical use. The theoretical background of the random incident sound absorption with reverberation room and normal incident sound absorption using impedance tube are well documented. The Transfer Matrix method for measuring transmission loss and absorption coefficient using impedance tube is very attractive since it is rather inexpensive and fast. In this research, a low-cost Impedance Tube is constructed using transfer function method to measure both absorption and transmissibility of materials. Equipment and measurement instruments available in the laboratory were used in the construction of the tube, adhering to cost-effectiveness. Care has been taken for precise construction of tube to ensure better measurement results. Further various samples varying from hard non-porous to soft porous materials were tested for absorption and sound transmission loss. Absorption values were also compared with reverberation room method with the available samples further ensuring the reliability of the newly constructed tube for future measurements.

  9. Frequency-domain method for measuring spectral properties in multiple-scattering media: methemoglobin absorption spectrum in a tissuelike phantom

    NASA Astrophysics Data System (ADS)

    Fishkin, Joshua B.; So, Peter T. C.; Cerussi, Albert E.; Gratton, Enrico; Fantini, Sergio; Franceschini, Maria Angela

    1995-03-01

    We have measured the optical absorption and scattering coefficient spectra of a multiple-scattering medium (i.e., a biological tissue-simulating phantom comprising a lipid colloid) containing methemoglobin by using frequency-domain techniques. The methemoglobin absorption spectrum determined in the multiple-scattering medium is in excellent agreement with a corrected methemoglobin absorption spectrum obtained from a steady-state spectrophotometer measurement of the optical density of a minimally scattering medium. The determination of the corrected methemoglobin absorption spectrum takes into account the scattering from impurities in the methemoglobin solution containing no lipid colloid. Frequency-domain techniques allow for the separation of the absorbing from the scattering properties of multiple-scattering media, and these techniques thus provide an absolute

  10. Retrieval of profile information from airborne multiaxis UV-visible skylight absorption measurements.

    PubMed

    Bruns, Marco; Buehler, Stefan A; Burrows, John P; Heue, Klaus-Peter; Platt, Ulrich; Pundt, Irene; Richter, Andreas; Rozanov, Alexej; Wagner, Thomas; Wang, Ping

    2004-08-01

    A recent development in ground-based remote sensing of atmospheric constituents by UV-visible absorption measurements of scattered light is the simultaneous use of several horizon viewing directions in addition to the traditional zenith-sky pointing. The different light paths through the atmosphere enable the vertical distribution of some atmospheric absorbers, such as NO2, BrO, or O3, to be retrieved. This approach has recently been implemented on an airborne platform. This novel instrument, the airborne multiaxis differential optical absorption spectrometer (AMAXDOAS), has been flown for the first time. In this study, the amount of profile information that can be retrieved from such measurements is investigated for the trace gas NO2. Sensitivity studies on synthetic data are performed for a variety of representative measurement conditions including two wavelengths, one in the UV and one in the visible, two different surface spectral reflectances, various lines of sight (LOSs), and for two different flight altitudes. The results demonstrate that the AMAXDOAS measurements contain useful profile information, mainly at flight altitude and below the aircraft. Depending on wavelength and LOS used, the vertical resolution of the retrieved profiles is as good as 2 km near flight altitude. Above 14 km the profile information content of AMAXDOAS measurements is sparse. Airborne multiaxis measurements are thus a promising tool for atmospheric studies in the troposphere and the upper troposphere and lower stratosphere region.

  11. Differential Optical Absorption Spectroscopy (DOAS) using Targets: SO2 and NO2 Measurements in Montevideo City

    NASA Astrophysics Data System (ADS)

    Louban, Ilia; Píriz, Gustavo; Platt, Ulrich; Frins, Erna

    2008-04-01

    SO2 and NO2 were remotely measured in a main street of Montevideo city using Multiaxis-Differential Optical Absorption Spectroscopy (MAX-DOAS) combined with on-field selected targets. Target-based measurements are the basis of a new experimental procedure called Topographic Target Light scattering-DOAS (TOTAL-DOAS) that provides a well define absorption path to measure the near surface distribution of trace gases in the boundary layer. It combines the measurement principles of the long-path DOAS and zenith-scattered sunlight DOAS, within the near UV and VIS spectral range. We give a general description of the procedure and present first results of the 2006 campaign at Montevideo.

  12. 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.

  13. 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.

  14. 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.

  15. 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®

  16. An instrumented pendulum system for measuring energy absorption during fracture insult to large animal joints in vivo.

    PubMed

    Diestelmeier, B W; Rudert, M J; Tochigi, Y; Baer, T E; Fredericks, D C; Brown, T D

    2014-06-01

    For systematic laboratory studies of bone fractures in general and intra-articular fractures in particular, it is often necessary to control for injury severity. Quantitatively, a parameter of primary interest in that regard is the energy absorbed during the injury event. For this purpose, a novel technique has been developed to measure energy absorption in experimental impaction. The specific application is for fracture insult to porcine hock (tibiotalar) joints in vivo, for which illustrative intra-operative data are reported. The instrumentation allowed for the measurement of the delivered kinetic energy and of the energy passed through the specimen during impaction. The energy absorbed by the specimen was calculated as the difference between those two values. A foam specimen validation study was first performed to compare the energy absorption measurements from the pendulum instrumentation versus the work of indentation performed by an MTS machine. Following validation, the pendulum apparatus was used to measure the energy absorbed during intra-articular fractures created in 14 minipig hock joints in vivo. The foam validation study showed close correspondence between the pendulum-measured energy absorption and MTS-performed work of indentation. In the survival animal series, the energy delivered ranged from 31.5 to 48.3 Js (41.3±4.0, mean±s.d.) and the proportion of energy absorbed to energy delivered ranged from 44.2% to 64.7% (53.6%±4.5%). The foam validation results support the reliability of the energy absorption measure provided by the instrumented pendulum system. Given that a very substantial proportion of delivered energy passed--unabsorbed--through the specimens, the energy absorption measure provided by this novel technique arguably provides better characterization of injury severity than is provided simply by energy delivery.

  17. Laser-based measurements of pressure broadening and pressure shift coefficients of combustion-relevant absorption lines in the near-infrared region

    NASA Astrophysics Data System (ADS)

    Bürkle, Sebastian; Walter, Nicole; Wagner, Steven

    2018-06-01

    A set of high-resolution absorption spectrometers based on TDLAS was used to determine the impact of combustion-relevant gases on the pressure shift and broadening of H2O, CO2, C2H2 and CH4 absorption lines in the near-infrared spectral region. In particular, self- and foreign-broadening coefficients induced by CO2, N2, O2, air, C2H2 and CH4 were measured. The absorption lines under investigation are suitable to measure the respective species in typical combustion environments via laser absorption spectroscopy. Additionally, species-dependent self- and foreign-induced pressure shift coefficients were measured and compared to the literature. The experiments were performed in two specifically designed absorption cells over a wide pressure range from 5 to 180 kPa. Different sources of uncertainty were identified and quantified to achieve relative measurement uncertainties of 0.7-1.5% for broadening coefficients and 0.6-1.6% for pressure shift coefficients.

  18. Raman gain and nonlinear optical absorption measurements in a low-loss silicon waveguide

    NASA Astrophysics Data System (ADS)

    Rong, Haisheng; Liu, Ansheng; Nicolaescu, Remus; Paniccia, Mario; Cohen, Oded; Hak, Dani

    2004-09-01

    We fabricated a low-loss (˜0.22dB/cm) rib waveguide (WG) in silicon-on-insulator with a small effective core area of ˜1.57μm2 and measured the stimulated Raman scattering gain in the WG. We obtained 2.3dB Raman gain in a 4.8-cm-long S-shaped WG using a 1455nm pump laser with a cw power of 0.9W measured before the WG. In addition, we observed nonlinear dependence of Raman gain and optical propagation loss as a function of the pump power. Our study shows that this mainly is due to two-photon absorption (TPA) induced free carrier absorption in the silicon WG. We experimentally determined the TPA induced free carrier lifetime of 25ns, which agrees well with our modeling.

  19. Measurement of laser absorptivity for operating parameters characteristic of laser drilling regime

    NASA Astrophysics Data System (ADS)

    Schneider, M.; Berthe, L.; Fabbro, R.; Muller, M.

    2008-08-01

    Laser drilling in the percussion regime is commonly used in the aircraft industry to drill sub-millimetre holes in metallic targets. Characteristic laser intensities in the range of 10 MW cm-2 are typically employed for drilling metallic targets. With these intensities the temperature of the irradiated matter is above the vaporization temperature and the drilling process is led by hydrodynamic effects. Although the main physical processes involved are identified, this process is not correctly understood or completely controlled. A major characteristic coefficient of laser-matter interaction for this regime, which is the absorptivity of the laser on the irradiated surface, is still unknown, because of the perturbing effects due to laser beam geometrical trapping inside the drilled hole. So, by using time resolved experiments, this study deals with the direct measurement of the variation of the intrinsic absorption of aluminium, nickel and steel materials, as a function of the incident laser intensity up to 20 MW cm-2. We observe that for this incident intensity, the absorptivity can reach up to 80%. This very high and unexpected value is discussed by considering the microscopic behaviour of the heated matter near the vapour-liquid interface that undergoes possible Rayleigh-Taylor instability or volume absorption.

  20. Quantification of sauter mean diameter in diesel sprays using scattering-absorption extinction measurements

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

    Martinez, Gabrielle L; Magnotti, Gina M; Knox, Benjamin W

    Quantitative measurements of the primary breakup process in diesel sprays are lacking due to a range of experimental and diagnostic challenges, including: high droplet number density environments, very small characteristic drop size scales (~1-10 μm), and high characteristic velocities in the primary breakup region (~600 m/s). Due to these challenges, existing measurement techniques have failed to resolve a sufficient range of the temporal and spatial scales involved and much remains unknown about the primary atomization process in practical diesel sprays. To gain a better insight into this process, we have developed a joint visible and x-ray extinction measurement technique tomore » quantify axial and radial distributions of the path-integrated Sauter Mean Diameter (SMD) and Liquid Volume Fraction (LVF) for diesel-like sprays. This technique enables measurement of the SMD in regions of moderate droplet number density, enabling construction of the temporal history of drop size development within practical diesel sprays. The experimental campaign was conducted jointly at the Georgia Institute of Technology and Argonne National Laboratory using the Engine Combustion Network “Spray D” injector. X-ray radiography liquid absorption measurements, conducted at the Advanced Photon Source at Argonne, quantify the liquid-fuel mass and volume distribution in the spray. Diffused back-illumination liquid scattering measurements were conducted at Georgia Tech to quantify the optical thickness throughout the spray. By application of Mie-scatter equations, the ratio of the absorption and scattering extinction measurements is demonstrated to yield solutions for the SMD. This work introduces the newly developed scattering-absorption measurement technique and highlights the important considerations that must be taken into account when jointly processing these measurements to extract the SMD. These considerations include co-alignment of measurements taken at different

  1. Calibration-free self-absorption model for measuring nitric oxide concentration in a pulsed corona discharge.

    PubMed

    Du, Yanjun; Ding, Yanjun; Liu, Yufeng; Lan, Lijuan; Peng, Zhimin

    2014-08-01

    The effect of self-absorption on emission intensity distributions can be used for species concentration measurements. A calculation model is developed based on the Beer-Lambert law to quantify this effect. And then, a calibration-free measurement method is proposed on the basis of this model by establishing the relationship between gas concentration and absorption strength. The effect of collision parameters and rotational temperature on the method is also discussed. The proposed method is verified by investigating the nitric oxide emission bands (A²Σ⁺→X²∏) that are generated by a pulsed corona discharge at various gas concentrations. Experiment results coincide well with the expectations, thus confirming the precision and accuracy of the proposed measurement method.

  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. WVR-GPS comparison measurements and calibration of the 20-32 GHz tropospheric water vapor absorption model.

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

    Keihm, S. J.; Bar-Server, Y.; Liljegren, J. C.

    2002-06-01

    Collocated measurements of opacity (from water vapor radiometer brightness temperatures) and wet path delay (from ground-based tracking of global positioning satellites) are used to constrain the model of atmospheric water vapor absorption in the 20-32 GHz band. A differential approach is presented in which the slope of opacity-versus-wet delay data is used as the absorption model constraint. This technique minimizes the effects of radiometric calibration errors and oxygen model uncertainties in the derivation of a best-fit vapor absorption model. A total of approximately five months of data was obtained from two experiment sites. At the Cloud and Radiation Testbed (CART)more » site near Lamont, Oklahoma, three independent water vapor radiometers (WVRs) provided near-continuous opacity measurements over the interval July-September 1998. At the NASA/Goldstone tracking station in the California desert two WVRs; obtained opacity data over the September-October 1997 interval. At both sites a Global Positioning Satellite (GPS) receiver and surface barometer obtained the data required for deriving the zenith wet delays over the same time frames. Measured values of the opacity-versus-wet delay slope parameter were obtained at four WVR frequencies (20.7, 22.2, 23.8, and 31.4 GHz) and compared with predictions of four candidate absorption models referenced in the literature. With one exception, all three models provide agreement within 5% of the opacity-versus-wet delay slope measurements at all WVR frequencies at both sites. One model provides agreement for all channels at both sites to the 2-3% level. This absorption model accuracy level represents a significant improvement over that attainable using radiosondes.« less

  4. Z-Scan Measurement of the Nonlinear Absorption of a Thin Gold Film

    NASA Technical Reports Server (NTRS)

    Smith, David D.; Yoon, Youngkwon; Boyd, Robert W.; Campbell, Joseph K.; Baker, Lane A.; Crooks, Richard M.; George, Michael

    1999-01-01

    We have used the z-scan technique at a wavelength (532 nm) near the transmission window of bulk gold to measure the nonlinear absorption coefficient of continuous approximately 50-Angstrom-thick gold films, deposited onto surface-modified quartz substrates. For highly absorbing media such as metals, we demonstrate that determination of either the real or imaginary part of the third-order susceptibility requires a measurement of both nonlinear absorption and nonlinear refraction, i.e. both open- and closed-aperture z-scans must be performed. Closed-aperture z-scans did not yield a sufficient signal for the determination of the nonlinear refraction. However, open-aperture z-scans yielded values ranging from Beta = 1.9 x 10(exp -3) to 5.3 x 10(exp -3) cm/W in good agreement with predictions which ascribe the nonlinear response to a Fermi smearing mechanism. We note that the sign of the nonlinearity is reversed from that of gold nanoparticle composites, in accordance with the predictions of mean field theories.

  5. Differential absorption lidar measurements of atmospheric water vapor using a pseudonoise code modulated AlGaAs laser. Thesis

    NASA Technical Reports Server (NTRS)

    Rall, Jonathan A. R.

    1994-01-01

    Lidar measurements using pseudonoise code modulated AlGaAs lasers are reported. Horizontal path lidar measurements were made at night to terrestrial targets at ranges of 5 and 13 km with 35 mW of average power and integration times of one second. Cloud and aerosol lidar measurements were made to thin cirrus clouds at 13 km altitude with Rayleigh (molecular) backscatter evident up to 9 km. Average transmitter power was 35 mW and measurement integration time was 20 minutes. An AlGaAs laser was used to characterize spectral properties of water vapor absorption lines at 811.617, 816.024, and 815.769 nm in a multipass absorption cell using derivative spectroscopy techniques. Frequency locking of an AlGaAs laser to a water vapor absorption line was achieved with a laser center frequency stability measured to better than one-fifth of the water vapor Doppler linewidth over several minutes. Differential absorption lidar measurements of atmospheric water vapor were made in both integrated path and range-resolved modes using an externally modulated AlGaAs laser. Mean water vapor number density was estimated from both integrated path and range-resolved DIAL measurements and agreed with measured humidity values to within 6.5 percent and 20 percent, respectively. Error sources were identified and their effects on estimates of water vapor number density calculated.

  6. Accuracy of delta 18O isotope ratio measurements on the same sample by continuous-flow isotope-ratio mass spectrometry

    USDA-ARS?s Scientific Manuscript database

    The doubly labeled water method is considered the reference method to measure energy expenditure. Conventional mass spectrometry requires a separate aliquot of the same sample to be prepared and analyzed separately. With continuous-flow isotope-ratio mass spectrometry, the same sample could be analy...

  7. 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.

  8. Simple system for measuring tritium Ad/absorption using a 2. pi. counter and thermal desorption spectrometer

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

    Miyake, H.; Matsuyama, M.; Watanabe, K.

    1992-03-01

    In this paper, the authors develop a simple system using tritium tracer and thermal desorption techniques to measure the tritium adsorption and/or absorption on/in a material having typical surface conditions: namely, not cleaned surface. The tritium counting devices used were a 2{pi} counter and conventional proportional counter. With this system, the amounts of ad/absorption could be measured without exposing the samples to air after exposing them to tritium gas. The overall efficiency (F) of the 2{pi} counter was described at F = exp({minus}2.64h), where h is the distance from the sample to the detector. Ad/absorption measurements were carried out formore » several materials used for fabricating conventional vacuum systems. The results were, in the order of decreasing amounts of ad/absorption, as (fiber reinforced plastics(FRP)) {gt} (nickel(Ni), molybdenum disulfide(MoS{sub 2})) {gt} (stainless steel (SS304), iron(Fe), aluminum alloy(A2219)) {gt} (boron nitride(h-BN), silicon carbide (SiC), SS304 passivated by anodic oxidation layers(ASS) and that by boron nitride segregation layers (BSS)). The relative amounts were abut 100 for Ni and 0.1 for ASS and BSS, being normalized to Fe = 1.« less

  9. Calibration system for radon EEC measurements.

    PubMed

    Mostafa, Y A M; Vasyanovich, M; Zhukovsky, M; Zaitceva, N

    2015-06-01

    The measurement of radon equivalent equilibrium concentration (EECRn) is very simple and quick technique for the estimation of radon progeny level in dwellings or working places. The most typical methods of EECRn measurements are alpha radiometry or alpha spectrometry. In such technique, the influence of alpha particle absorption in filters and filter effectiveness should be taken into account. In the authors' work, it is demonstrated that more precise and less complicated calibration of EECRn-measuring equipment can be conducted by the use of the gamma spectrometer as a reference measuring device. It was demonstrated that for this calibration technique systematic error does not exceed 3 %. The random error of (214)Bi activity measurements is in the range 3-6 %. In general, both these errors can be decreased. The measurements of EECRn by gamma spectrometry and improved alpha radiometry are in good agreement, but the systematic shift between average values can be observed. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  10. Measurement of absorption rates of HFC single and blended refrigerants in POE oils

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

    Leung, M.; Jotshi, C.K.; Goswami, D.Y.

    1999-07-01

    Thermophysical properties of refrigerant/lubricant mixtures play an important role in refrigeration and air-conditioning system design. Therefore it is important to have a good understanding of the mixture composition in each system component such as the compressor or evaporator. Because the system operation is dynamic the rates of absorption and desorption become significant parameters. In this paper measured absorption rates of alternative refrigerants in polyolester (POE) oils are reported. An effective online mass gain method was designed and constructed to measure the absorption rates and solubility of refrigerants in lubricants. HFC single refrigerants (R-32, R-125, R-134a, and R-143a), and blended refrigerantsmore » (R-404A, R-407C, and R-410A) were tested with POE ISO 68 lubricant under various conditions. The experimental results showed that, at room temperature, R-134a is the most soluble in POE ISO 68 oil among all the refrigerants tested at pressures of 239 kPa (20 psig) to 446 kPa (70 psig). Among the blended refrigerants tested, R-407C was found to be the most soluble at room temperature and pressures of 239 kPa and 446 kPa. Experimental solubility data from this new measurement method were compared with data available in the literature. Good agreement between the two indicates the feasibility of the new method employed in this investigation.« less

  11. 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.

  12. 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.

  13. 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.

  14. Laboratory measurement of the absorption coefficient of riboflavin for ultraviolet light (365 nm).

    PubMed

    Iseli, Hans Peter; Popp, Max; Seiler, Theo; Spoerl, Eberhard; Mrochen, Michael

    2011-03-01

    Corneal cross-linking (CXL) is an increasingly used treatment technique for stabilizing the cornea in keratoconus. Cross-linking (polymerization) between collagen fibrils is induced by riboflavin (vitamin B2) and ultraviolet light (365 nm). Although reported to reach a constant value at higher riboflavin concentrations, the Lambert-Beer law predicts a linear increase in the absorption coefficient. This work was carried out to determine absorption behavior at different riboflavin concentrations and to further investigate the purported plateau absorption coefficient value of riboflavin and to identify possible bleaching effects. The Lambert-Beer law was used to calculate the absorption coefficient at various riboflavin concentrations. The following investigated concentrations of riboflavin solutions were prepared using a mixture of 0.5% riboflavin and 20% Dextran T500 dissolved in 0.9% sodium chloride solution: 0%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.08%, 0.1%, 0.2%, 0.3%, 0.4%, and 0.5%, and were investigated with and without aperture plate implementation. An additional test series measured the transmitted power at selected riboflavin concentrations over time. In diluted solutions, a linear correlation exists between the absorption coefficient and riboflavin concentration. The absorption coefficient reaches a plateau, but this occurs at a higher riboflavin concentration (0.1%) than previously reported (just above 0.04%). Transmitted light power increases over time, indicating a bleaching effect of riboflavin. The riboflavin concentration can be effectively varied as a treatment parameter in a considerably broader range than previously thought. Copyright 2011, SLACK Incorporated.

  15. Non-uniform temperature and species concentration measurements in a laminar flame using multi-band infrared absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Ma, Liu Hao; Lau, Lok Yin; Ren, Wei

    2017-03-01

    We report in situ measurements of non-uniform temperature, H2O and CO2 concentration distributions in a premixed methane-air laminar flame using tunable diode laser absorption spectroscopy (TDLAS). A mid-infrared, continuous-wave, room-temperature interband cascade laser (ICL) at 4183 nm was used for the sensitive detection of CO2 at high temperature.The H2O absorption lines were exploited by one distributed feedback (DFB) diode laser at 1343 nm and one ICL at 2482 nm to achieve multi-band absorption measurements with high species concentration sensitivity, high temperature sensitivity, and immunity to variations in ambient conditions. A novel profile-fitting function was proposed to characterize the non-uniform temperature and species concentrations along the line-of-sight in the flame by detecting six absorption lines of CO2 and H2O simultaneously. The flame temperature distribution was measured at different heights above the burner (5-20 mm), and compared with the thermocouple measurement with heat-transfer correction. Our TDLAS measured temperature of the central flame was in excellent agreement (<1.5% difference) with the thermocouple data.The TDLAS results were also compared with the CFD simulations using a detailed chemical kinetics mechanism (GRI 3.0) and considering the heat loss to the surroundings.The current CFD simulation overpredicted the flame temperature in the gradient region, but was in excellent agreement with the measured temperature and species concentration in the core of the flame.

  16. 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.

  17. Measurement of gluconeogenesis using glucose fragments and mass spectrometry after ingestion of deuterium oxide.

    USDA-ARS?s Scientific Manuscript database

    We report a new method to measure the fraction of glucose derived from gluconeogenesis using gas chromatography-mass spectrometry and positive chemical ionization. After ingestion of deuterium oxide by subjects, glucose derived from gluconeogenesis is labeled with deuterium. Our calculations of gluc...

  18. 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.

  19. 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.

  20. Measurement of water absorption capacity in wheat flour by a headspace gas chromatographic technique.

    PubMed

    Xie, Wei-Qi; Yu, Kong-Xian; Gong, Yi-Xian

    2018-04-17

    The purpose of this work is to introduce a new method for quantitatively analyzing water absorption capacity in wheat flour by a headspace gas chromatographic technique. This headspace gas chromatographic technique was based on measuring the water vapor released from a series of wheat flour samples with different contents of water addition. According to the different trends between the vapor and wheat flour phase before and after the water absorption capacity in wheat flour, a turning point (corresponding to water absorption capacity in wheat flour) can be obtained by fitting the data of the water gas chromatography peak area from different wheat flour samples. The data showed that the phase equilibrium in the vial can be achieved in 25 min at desired temperature (35°C). The relative standard deviation of the reaction headspace gas chromatographic technique in water absorption capacity determination was within 3.48%, the relative differences has been determined by comparing the water absorption capacity obtained from this new analytical technique with the data from the reference technique (i.e., the filtration method), which are less than 8.92%. The new headspace gas chromatographic method is automated, accurate and be a reliable tool for quantifying water absorption capacity in wheat flour in both laboratory research and mill applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Nanowire dopant measurement using secondary ion mass spectrometry

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

    Chia, A. C. E.; Boulanger, J. P.; Wood, B. A.

    2015-09-21

    A method is presented to improve the quantitative determination of dopant concentration in semiconductor nanowire (NW) arrays using secondary ion mass spectrometry (SIMS). SIMS measurements were used to determine Be dopant concentrations in a Be-doped GaAs thin film and NW arrays of various pitches that were dry-etched from the same film. A comparison of these measurements revealed a factor of 3 to 12 difference, depending on the NW array pitch, between the secondary Be ion yields of the film and the NW arrays, despite being identically doped. This was due to matrix effects and ion beam mixing of Be frommore » the NWs into the surrounding benzocyclobutene that was used to fill the space between the NWs. This indicates the need for etched NWs to be used as doping standards instead of 2D films when evaluating NWs of unknown doping by SIMS. Using the etched NWs as doping standards, NW arrays of various pitches grown by the vapour-liquid-solid mechanism were characterized by SIMS to yield valuable insights into doping mechanisms.« less

  2. Airborne Carbon Dioxide Laser Absorption Spectrometer for IPDA Measurements of Tropospheric CO2: Recent Results

    NASA Technical Reports Server (NTRS)

    Spiers, Gary D.; Menzies, Robert T.

    2008-01-01

    The National Research Council's decadal survey on Earth Science and Applications from Space[1] recommended the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission for launch in 2013-2016 as a logical follow-on to the Orbiting Carbon Observatory (OCO) which is scheduled for launch in late 2008 [2]. The use of a laser absorption measurement technique provides the required ability to make day and night measurements of CO2 over all latitudes and seasons. As a demonstrator for an approach to meeting the instrument needs for the ASCENDS mission we have developed the airborne Carbon Dioxide Laser Absorption Spectrometer (CO2LAS) which uses the Integrated Path Differential Absorption (IPDA) Spectrometer [3] technique operating in the 2 micron wavelength region.. During 2006 a short engineering checkout flight of the CO2LAS was conducted and the results presented previously [4]. Several short flight campaigns were conducted during 2007 and we report results from these campaigns.

  3. 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).

  4. 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.

  5. 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.

  6. High-resolution optical measurements of atmospheric winds from space. I - Lower atmosphere molecular absorption

    NASA Technical Reports Server (NTRS)

    Hays, P. B.

    1982-01-01

    A high-resolution spectroscopic technique, analogous to that used in the thermosphere to measure the vector wind fields in the upper troposphere and stratosphere, is described which uses narrow features in the spectrum of light scattered from the earth's lower atmosphere to provide Doppler information on atmospheric scattering and absorption. It is demonstrated that vector winds can be measured from a satellite throughout the lower atmosphere, using a multiple-etalon Fabry-Perot interferometer of modest aperture. It is found that molecular oxygen and water vapor absorption lines in the spectrum of sunlight scattered by the atmosphere are Doppler-shifted by the line of sight wind, so that they may be used to monitor the global wind systems in the upper troposphere and stratosphere.

  7. 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.

  8. Photothermal measurement of absorption and scattering losses in thin films excited by surface plasmons.

    PubMed

    Domené, Esteban A; Balzarotti, Francisco; Bragas, Andrea V; Martínez, Oscar E

    2009-12-15

    We present a novel noncontact, photothermal technique, based on the focus error signal of a commercial CD pickup head that allows direct determination of absorption in thin films. Combined with extinction methods, this technique yields the scattering contribution to the losses. Surface plasmon polaritons are excited using the Kretschmann configuration in thin Au films of varying thickness. By measuring the extinction and absorption simultaneously, it is shown that dielectric constants and thickness retrieval leads to inconsistencies if the model does not account for scattering.

  9. Resonant tube for measurement of sound absorption in gases at low frequency/pressure ratios

    NASA Technical Reports Server (NTRS)

    Zuckerwar, A. J.; Griffin, W. A.

    1980-01-01

    The paper describes a resonant tube for measuring sound absorption in gases, with specific emphasis on the vibrational relaxation peak of N2, over a range of frequency/pressure ratios from 0.1 to 2500 Hz/atm. The experimental background losses measured in argon agree with the theoretical wall losses except at few isolated frequencies. Rigid cavity terminations, external excitation, and a differential technique of background evaluation were used to minimize spurious contributions to the background losses. Room temperature measurements of sound absorption in binary mixtures of N2-CO2 in which both components are excitable resulted in the maximum frequency/pressure ratio in Hz/atm of 0.063 + 123m for the N2 vibrational relaxation peak, where m is mole percent of added CO2; the maximum ratio for the CO2 peak was 34,500 268m where m is mole percent of added N2.

  10. In Situ Density Measurement of Basaltic Melts at High Pressure by X-ray Absorption Method

    NASA Astrophysics Data System (ADS)

    Ando, R.; Ohtani, E.; Suzuki, A.; Urakawa, S.; Katayama, Y.

    2004-12-01

    Density of silicate melt at high pressure is one of the most important properties to understand magma migration in the planetary interior. However, because of experimental difficulties, the density of magma at high pressure is poorly known. Katayama et al. (1996) recently developed a new in situ density measurement method for metallic melts, based on the density dependency of X-ray absorption in the sample. In this study, we tried to measure the density of basaltic melt by this absorption method. When X-ray is transmitted to the sample, the intensity of the transmitted X-ray beam (I) is expressed as follows; I=I0exp(-μ ρ t), where I0 is the intensity of incident X-ray beam, μ is the mass absorption coefficient, ρ is the density of the sample, and t is the thickness of the sample. If t and μ are known, we can determine the density of the sample by measuring I and I0. This is the principle of the absorption method for density measurement. In this study, in order to determine t, we used a single crystalline diamond cylinder as a sample capsule, diamond is less compressive and less deformable so that even at high pressure t (thickness of the sample at the point x) is expressed as follows; t = 2*(R02-x2)1/2, R0 is the inner radius of cylinder at the ambient condition, and x is distance from a center of the capsule. And diamond also shows less absorption so that this make it possible to measure the density of silicate melt with smaller absorption coefficient than metallic melts. In order to know the μ of the sample, we measured both densities (ρ ) and absorptions (I/I0) for some glasses and crystals with same composition of the sample at the ambient condition, and calculated as fallows; μ =ln(I/I0)/ρ . Experiments were made at the beamline (BL22XU) of SPring-8. For generation of high pressure and high temperature, we used DIA-type cubic anvil apparatus (SMAP180) there. We used tungsten carbide anvils with the edge-length of 6 mm. The energy of monochromatic X

  11. 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.

  12. 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.

  13. Absorptivity Measurements and Heat Source Modeling to Simulate Laser Cladding

    NASA Astrophysics Data System (ADS)

    Wirth, Florian; Eisenbarth, Daniel; Wegener, Konrad

    The laser cladding process gains importance, as it does not only allow the application of surface coatings, but also additive manufacturing of three-dimensional parts. In both cases, process simulation can contribute to process optimization. Heat source modeling is one of the main issues for an accurate model and simulation of the laser cladding process. While the laser beam intensity distribution is readily known, the other two main effects on the process' heat input are non-trivial. Namely the measurement of the absorptivity of the applied materials as well as the powder attenuation. Therefore, calorimetry measurements were carried out. The measurement method and the measurement results for laser cladding of Stellite 6 on structural steel S 235 and for the processing of Inconel 625 are presented both using a CO2 laser as well as a high power diode laser (HPDL). Additionally, a heat source model is deduced.

  14. 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.

  15. Airborne Lidar measurements of Atmospheric CO2 Column Absorption and Line Shapes from 3-11 km altitudes

    NASA Astrophysics Data System (ADS)

    Abshire, J. B.; Riris, H.; Allan, G. R.; Weaver, C.; Mao, J.; Hasselbrack, W.

    2009-04-01

    Accurate measurements of tropospheric CO2 abundances with global-coverage are needed to quantify processes that regulate CO2 exchange with the land and oceans. The 2007 Decadal Survey for Earth Science by the US National Research Council recommended a space-based CO2 measuring mission called ASCENDS. We have been developing a technique for the remote measurement of tropospheric CO2 concentrations from aircraft and as a candidate for the ASCENDS mission. It uses the 1570-nm CO2 band and a dual channel laser absorption spectrometer (ie DIAL used in altimeter mode). It uses several tunable laser transmitters allowing simultaneous measurement of the absorption from a CO2 absorption line in the 1570 nm band, O2 extinction in the oxygen A-band, and surface height and aerosol backscatter in the same path. It directs the narrow co-aligned laser beams toward nadir, and measures the energy of the laser echoes reflected from land and water surfaces. During the measurement, the lasers are stepped in wavelength across the CO2 line and an O2 line (near 765 nm) at a ~ 1 kHz rate. The receiver uses a telescope and photon counting detectors, and measures the background light and energies of the laser echoes from the surface along with scattering from any aerosols in the path. The gas extinction and column densities for the CO2 and O2 gases are estimated from the ratio of the on- and off- line signals via the DIAL technique. We use pulsed laser signals and time gating to isolate the laser echo signals from the surface, and to reject photons scattered from thin clouds and aerosols in the path. Previously we had constructed breadboard versions of our CO2 and O2 sensors, using tunable diode lasers, fiber laser amplifiers and 20 cm diameter telescopes. We have used them to make measurements of gas absorptions over 0.2, 0.4 and 1.3 km long outdoor paths. We also have also calculated several characteristics of the technique for space and have performed an initial space mission

  16. Laser ablation inductively coupled plasma mass spectrometry measurement of isotope ratios in depleted uranium contaminated soils.

    PubMed

    Seltzer, Michael D

    2003-09-01

    Laser ablation of pressed soil pellets was examined as a means of direct sample introduction to enable inductively coupled plasma mass spectrometry (ICP-MS) screening of soils for residual depleted uranium (DU) contamination. Differentiation between depleted uranium, an anthropogenic contaminant, and naturally occurring uranium was accomplished on the basis of measured 235U/238U isotope ratios. The amount of sample preparation required for laser ablation is considerably less than that typically required for aqueous sample introduction. The amount of hazardous laboratory waste generated is diminished accordingly. During the present investigation, 235U/238U isotope ratios measured for field samples were in good agreement with those derived from gamma spectrometry measurements. However, substantial compensation was required to mitigate the effects of impaired pulse counting attributed to sample inhomogeneity and sporadic introduction of uranium analyte into the plasma.

  17. Laboratory Measurements of SO2 and N2 Absorption Spectra for Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Stark, Glenn

    2003-01-01

    This laboratory project focuses on the following topics: 1) Measurement of SO2 ultraviolet absorption cross sections; and 2) N2 band and Line Oscillator Strengths and Line Widths in the 80 to 100 nm region. Accomplishments for these projects are summarized.

  18. The airborne Laser Absorption Spectrometer - A new instrument of remote measurement of atmospheric trace gases

    NASA Technical Reports Server (NTRS)

    Shumate, M. S.; Menzies, R. T.

    1978-01-01

    The Laser Absorption Spectrometer is a portable instrument developed by JPL for remote measurement of trace gases from an aircraft platform. It contains two carbon dioxide lasers, two optical heterodyne receivers, appropriate optics to aim the lasers at the ground and detect the backscattered energy, and signal processing and recording electronics. Operating in the differential-absorption mode, it is possible to monitor one atmospheric gas at a time and record the data in real time. The system can presently measure ozone, ethylene, water vapor, and chlorofluoromethanes with high sensitivity. Airborne measurements were made in early 1977 from the NASA/JPL twin-engine Beechcraft and in May 1977 from the NASA Convair 990 during the ASSESS-II Shuttle Simulation Study. These flights resulted in measurements of ozone concentrations in the lower troposphere which were compared with ground-based values provided by the Air Pollution Control District. This paper describes the details of the instrument and results of the airborne measurements.

  19. 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

  20. First total-absorption spectroscopy measurement on the neutron-rich Cu isotopes

    NASA Astrophysics Data System (ADS)

    Naqvi, F.; Spyrou, A.; Liddick, S. N.; Larsen, A. C.; Guttormsen, M.; Bleuel, D. L.; Campo, L. C.; Couture, A.; Crider, B. P.; Dombos, A. C.; Ginter, T.; Lewis, R.; Mosby, S.; Perdikakis, G.; Prokop, C. P.; Quinn, S. J.; Renstrom, T.; Rubio, B.; Siem, S.

    2015-10-01

    The first beta-decay studies of 73-71Cu isotopes using the Total Absorption Spectroscopy (TAS) will be reported. The Cu isotopes have one proton outside the Z = 28 shell and hence are good candidates to probe the single-particle structure in the region.Theories predict weakening of the Z = 28 shell gap due to the tensor interaction between the valence πν single-particle orbitals. Comparing the beta-decay strength distributions in the daughter Zn isotopes to the theoretical calculations will provide a stringent test of the predictions. The experiment was performed at the National Superconducting Cyclotron Laboratory (NSCL) employing the TAS technique with the Summing NaI(Tl) detector, while beta decays were measured in the NSCL beta-counting system. The experimentally obtained total absorption spectra for the neutron-rich Cu isotopes will be presented and the implications of the extracted beta-feeding intensities will be discussed.

  1. Apparatus and method for measurement of weak optical absorptions by thermally induced laser pulsing

    DOEpatents

    Cremers, David A.; Keller, Richard A.

    1985-01-01

    The thermal lensing phenomenon is used as the basis for measurement of weak optical absorptions when a cell containing the sample to be investigated is inserted into a normally continuous-wave operation laser-pumped dye laser cavity for which the output coupler is deliberately tilted relative to intracavity circulating laser light, and pulsed laser output ensues, the pulsewidth of which can be related to the sample absorptivity by a simple algorithm or calibration curve. A minimum detection limit of less than 10.sup.-5 cm.sup.-1 has been demonstrated using this technique.

  2. Apparatus and method for measurement of weak optical absorptions by thermally induced laser pulsing

    DOEpatents

    Cremers, D.A.; Keller, R.A.

    1982-06-08

    The thermal lensing phenomenon is used as the basis for measurement of weak optical absorptions when a cell containing the sample to be investigated is inserted into a normally continuous-wave operation laser-pumped dye laser cavity for which the output coupler is deliberately tilted relative to intracavity circulating laser light, and pulsed laser output ensues, the pulsewidth of which can be rlated to the sample absorptivity by a simple algorithm or calibration curve. A minimum detection limit of less than 10/sup -5/ cm/sup -1/ has been demonstrated using this technique.

  3. Model studies of laser absorption computed tomography for remote air pollution measurement

    NASA Technical Reports Server (NTRS)

    Wolfe, D. C., Jr.; Byer, R. L.

    1982-01-01

    Model studies of the potential of laser absorption-computed tomography are presented which demonstrate the possibility of sensitive remote atmospheric pollutant measurements, over kilometer-sized areas, with two-dimensional resolution, at modest laser source powers. An analysis of this tomographic reconstruction process as a function of measurement SNR, laser power, range, and system geometry, shows that the system is able to yield two-dimensional maps of pollutant concentrations at ranges and resolutions superior to those attainable with existing, direct-detection laser radars.

  4. Laboratory Measurements of the 940, 1130, and 1370 nm Water Vapor Absorption Band Profiles

    NASA Technical Reports Server (NTRS)

    Giver, Lawrence P.; Gore, Warren J.; Pilewskie, P.; Freedman, R. S.; Chackerian, C., Jr.; Varanasi, P.

    2001-01-01

    We have used the solar spectral flux radiometer (SSFR) flight instrument with the Ames 25 meter base-path White cell to obtain about 20 moderate resolution (8 nm) pure water vapor spectra from 650 to 1650 nm, with absorbing paths from 806 to 1506 meters and pressures up to 14 torr. We also obtained a set at 806 meters with several different air-broadening pressures. Model simulations were made for the 940, 1130, and 1370 nm absorption bands for some of these laboratory conditions using the Rothman, et al HITRAN-2000 linelist. This new compilation of HITRAN includes new intensity measurements for the 940 nm region. We compared simulations for our spectra of this band using HITRAN-2000 with simulations using the prior HITRAN-1996. The simulations of the 1130 nm band show about 10% less absorption than we measured. There is some evidence that the total intensity of this band is about 38% stronger than the sum of the HITRAN line intensities in this region. In our laboratory conditions the absorption depends approximately on the square root of the intensity. Thus, our measurements agree that the band is stronger than tabulated in HITRAN, but by about 20%, substantially less than the published value. Significant differences have been shown between Doppler-limited resolution spectra of the 1370 nm band obtained at the Pacific Northwest National Laboratory and HITRAN simulations. Additional new intensity measurements in this region are continuing to be made. We expect the simulations of our SSFR lab data of this band will show the relative importance of improving the HITRAN line intensities of this band for atmospheric measurements.

  5. Concentration of Uranium Radioisotopes in Albanian Drinking Waters Measured by Alpha Spectrometry

    NASA Astrophysics Data System (ADS)

    Bylyku, Elida; Cfarku, Florinda; Deda, Antoneta; Bode, Kozeta; Fishka, Kujtim

    2010-01-01

    Uranium is a radioactive material that is frequently found in rocks and soil. When uranium decays, it changes into different elements that are also radioactive, including radon, a gas that is known to cause a lung cancer. The main concern with uranium in drinking water is harm to the kidneys. Public water systems are required to keep uranium levels at or below 500 mBq per liter to protect against kidney damage. Such an interest is needed due to safety, regulatory compliance and disposal issue for uranium in the environment since uranium is included as an obligatory controlled radionuclide in the European Legislation (Directive 98/83 CE of Council of 03.11.1998). The aim of this work is to measure the levels of uranium in drinking and drilled well waters in Albania. At first each sample was measured for total Alpha and total Beta activity. The samples with the highest levels of total alpha activity were chosen for the determination of uranium radioisotopes by alpha spectrometry. A radiochemical procedure using extraction with TBP (Tri-Butyl-Phosphate) is used in the presence of U232 as a yield tracer. Thin sources for alpha spectrometry are prepared by electrodepositing on to stainless steel discs. The results of the U238 activity measured in the different samples, depending from their geological origin range between 0.55-13.87 mBq/l. All samples measured results under the European Directive limits for U238 (5-500 mBq/1), Dose Coefficients according to Directive 96/29 EURATOM.

  6. Differential-optoacoustic absorption detector

    NASA Technical Reports Server (NTRS)

    Shumate, M. S.

    1977-01-01

    Two-cell spectrophone detects trace amounts of atmospheric pollutants by measuring absorption coefficients of gases with various laser sources. Device measures pressure difference between two tapered cells with differential manometer. Background signal is reduced by balanced window heating and balanced carrier gas absorption in two cells.

  7. Atmospheric extinction in solar tower plants: the Absorption and Broadband Correction for MOR measurements

    NASA Astrophysics Data System (ADS)

    Hanrieder, N.; Wilbert, S.; Pitz-Paal, R.; Emde, C.; Gasteiger, J.; Mayer, B.; Polo, J.

    2015-05-01

    Losses of reflected Direct Normal Irradiance due to atmospheric extinction in concentrating solar tower plants can vary significantly with site and time. The losses of the direct normal irradiance between the heliostat field and receiver in a solar tower plant are mainly caused by atmospheric scattering and absorption by aerosol and water vapor concentration in the atmospheric boundary layer. Due to a high aerosol particle number, radiation losses can be significantly larger in desert environments compared to the standard atmospheric conditions which are usually considered in raytracing or plant optimization tools. Information about on-site atmospheric extinction is only rarely available. To measure these radiation losses, two different commercially available instruments were tested and more than 19 months of measurements were collected at the Plataforma Solar de Almería and compared. Both instruments are primarily used to determine the meteorological optical range (MOR). The Vaisala FS11 scatterometer is based on a monochromatic near-infrared light source emission and measures the strength of scattering processes in a small air volume mainly caused by aerosol particles. The Optec LPV4 long-path visibility transmissometer determines the monochromatic attenuation between a light-emitting diode (LED) light source at 532 nm and a receiver and therefore also accounts for absorption processes. As the broadband solar attenuation is of interest for solar resource assessment for Concentrating Solar Power (CSP), a correction procedure for these two instruments is developed and tested. This procedure includes a spectral correction of both instruments from monochromatic to broadband attenuation. That means the attenuation is corrected for the actual, time-dependent by the collector reflected solar spectrum. Further, an absorption correction for the Vaisala FS11 scatterometer is implemented. To optimize the Absorption and Broadband Correction (ABC) procedure, additional

  8. Precise methane absorption measurements in the 1.64 μm spectral region for the MERLIN mission.

    PubMed

    Delahaye, T; Maxwell, S E; Reed, Z D; Lin, H; Hodges, J T; Sung, K; Devi, V M; Warneke, T; Spietz, P; Tran, H

    2016-06-27

    In this article we describe a high-precision laboratory measurement targeting the R(6) manifold of the 2 ν 3 band of 12 CH 4 . Accurate physical models of this absorption spectrum will be required by the Franco-German, Methane Remote Sensing LIDAR (MERLIN) space mission for retrievals of atmospheric methane. The analysis uses the Hartmann-Tran profile for modeling line shape and also includes line-mixing effects. To this end, six high-resolution and high signal-to-noise absorption spectra of air-broadened methane were recorded using a frequency-stabilized cavity ring-down spectroscopy apparatus. Sample conditions corresponded to room temperature and spanned total sample pressures of 40 hPa - 1013 hPa with methane molar fractions between 1 μmol mol -1 and 12 μmol mol -1 . All spectroscopic model parameters were simultaneously adjusted in a multispectrum nonlinear least-squares fit to the six measured spectra. Comparison of the fitted model to the measured spectra reveals the ability to calculate the room-temperature, methane absorption coefficient to better than 0.1% at the on-line position of the MERLIN mission. This is the first time that such fidelity has been reached in modeling methane absorption in the investigated spectral region, fulfilling the accuracy requirements of the MERLIN mission. We also found excellent agreement when comparing the present results with measurements obtained over different pressure conditions and using other laboratory techniques. Finally, we also evaluated the impact of these new spectral parameters on atmospheric transmissions spectra calculations.

  9. Precise methane absorption measurements in the 1.64 μm spectral region for the MERLIN mission

    PubMed Central

    Delahaye, T.; Maxwell, S.E.; Reed, Z.D.; Lin, H.; Hodges, J.T.; Sung, K.; Devi, V.M.; Warneke, T.; Spietz, P.; Tran, H.

    2016-01-01

    In this article we describe a high-precision laboratory measurement targeting the R(6) manifold of the 2ν3 band of 12CH4. Accurate physical models of this absorption spectrum will be required by the Franco-German, Methane Remote Sensing LIDAR (MERLIN) space mission for retrievals of atmospheric methane. The analysis uses the Hartmann-Tran profile for modeling line shape and also includes line-mixing effects. To this end, six high-resolution and high signal-to-noise absorption spectra of air-broadened methane were recorded using a frequency-stabilized cavity ring-down spectroscopy apparatus. Sample conditions corresponded to room temperature and spanned total sample pressures of 40 hPa – 1013 hPa with methane molar fractions between 1 μmol mol−1 and 12 μmol mol−1. All spectroscopic model parameters were simultaneously adjusted in a multispectrum nonlinear least-squares fit to the six measured spectra. Comparison of the fitted model to the measured spectra reveals the ability to calculate the room-temperature, methane absorption coefficient to better than 0.1% at the on-line position of the MERLIN mission. This is the first time that such fidelity has been reached in modeling methane absorption in the investigated spectral region, fulfilling the accuracy requirements of the MERLIN mission. We also found excellent agreement when comparing the present results with measurements obtained over different pressure conditions and using other laboratory techniques. Finally, we also evaluated the impact of these new spectral parameters on atmospheric transmissions spectra calculations. PMID:27551656

  10. 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.

  11. Ultraviolet absorption spectrum of HOCl

    NASA Technical Reports Server (NTRS)

    Burkholder, James B.

    1993-01-01

    The room temperature UV absorption spectrum of HOCl was measured over the wavelength range 200 to 380 nm with a diode array spectrometer. The absorption spectrum was identified from UV absorption spectra recorded following UV photolysis of equilibrium mixtures of Cl2O/H2O/HOCl. The HOCl spectrum is continuous with a maximum at 242 nm and a secondary peak at 304 nm. The measured absorption cross section at 242 nm was (2.1 +/- 0.3) x 10 exp -19/sq cm (2 sigma error limits). These results are in excellent agreement with the work of Knauth et al. (1979) but in poor agreement with the more recent measurements of Mishalanie et al. (1986) and Permien et al. (1988). An HOCl nu2 infrared band intensity of 230 +/- 35/sq cm atm was determined based on this UV absorption cross section. The present results are compared with these previous measurements and the discrepancies are discussed.

  12. Water vapor self-continuum absorption measurements in the 4.0 and 2.1 μm transparency windows

    NASA Astrophysics Data System (ADS)

    Richard, L.; Vasilchenko, S.; Mondelain, D.; Ventrillard, I.; Romanini, D.; Campargue, A.

    2017-11-01

    In a recent contribution [A. Campargue, S. Kassi, D. Mondelain, S. Vasilchenko, D. Romanini, Accurate laboratory determination of the near infrared water vapor self-continuum: A test of the MT_CKD model. J. Geophys. Res. Atmos., 121,13,180-13,203, doi:10.1002/2016JD025531], we reported accurate water vapor absorption continuum measurements by Cavity Ring-down Spectroscopy (CRDS) and Optical-Feedback-Cavity Enhanced Absorption Spectroscopy (OF-CEAS) at selected spectral points of 4 near infrared transparency windows. In the present work, the self-continuum cross-sections, CS, are determined for two new spectral points. The 2491 cm-1 spectral point in the region of maximum transparency of the 4.0 μm window was measured by OF-CEAS in the 23-52 °C temperature range. The 4435 cm-1 spectral point of the 2.1 μm window was measured by CRDS at room temperature. The self-continuum cross-sections were determined from the pressure squared dependence of the continuum absorption. Comparison to the literature shows a reasonable agreement with 1970 s and 1980 s measurements using a grating spectrograph in the 4.0 μm window and a very good consistency with our previous laser measurements in the 2.1 μm window. For both studied spectral points, our values are much smaller than previous room temperature measurements by Fourier Transform Spectroscopy. Significant deviations (up to about a factor 4) are noted compared to the widely used semi empirical MT_CKD model of the absorption continuum. The measured temperature dependence at 2491 cm-1 is consistent with previous high temperature measurements in the 4.0 μm window and follows an exp(D0/kT) law, D0 being the dissociation energy of the water dimer.

  13. Ultraviolet absorption: Experiment MA-059. [measurement of atmospheric species concentrations

    NASA Technical Reports Server (NTRS)

    Donahue, T. M.; Hudson, R. D.; Rawlins, W. T.; Anderson, J.; Kaufman, F.; Mcelroy, M. B.

    1977-01-01

    A technique devised to permit the measurement of atmospheric species concentrations is described. This technique involves the application of atomic absorption spectroscopy and the quantitative observation of resonance fluorescence in which atomic or molecular species scatter resonance radiation from a light source into a detector. A beam of atomic oxygen and atomic nitrogen resonance radiation, strong unabsorbable oxygen and nitrogen radiation, and visual radiation was sent from Apollo to Soyuz. The density of atomic oxygen and atomic nitrogen between the two spacecraft was measured by observing the amount of resonance radiation absorbed when the line joining Apollo and Soyuz was perpendicular to their velocity with respect to the ambient atmosphere. Results of postflight analysis of the resonance fluorescence data are discussed.

  14. Impact of Tropospheric Aerosol Absorption on Ozone Retrieval from buv Measurements

    NASA Technical Reports Server (NTRS)

    Torres, O.; Bhartia, P. K.

    1998-01-01

    The impact of tropospheric aerosols on the retrieval of column ozone amounts using spaceborne measurements of backscattered ultraviolet radiation is examined. Using radiative transfer calculations, we show that uv-absorbing desert dust may introduce errors as large as 10% in ozone column amount, depending on the aerosol layer height and optical depth. Smaller errors are produced by carbonaceous aerosols that result from biomass burning. Though the error is produced by complex interactions between ozone absorption (both stratospheric and tropospheric), aerosol scattering, and aerosol absorption, a surprisingly simple correction procedure reduces the error to about 1%, for a variety of aerosols and for a wide range of aerosol loading. Comparison of the corrected TOMS data with operational data indicates that though the zonal mean total ozone derived from TOMS are not significantly affected by these errors, localized affects in the tropics can be large enough to seriously affect the studies of tropospheric ozone that are currently undergoing using the TOMS data.

  15. Temperature dependent absorption measurement of various transition metal doped laser materials

    NASA Astrophysics Data System (ADS)

    Horackova, Lucie; Šulc, Jan; Jelinkova, Helena; Jambunathan, Venkatesan; Lucianetti, Antonio; Mocek, Tomás.

    2015-05-01

    In recent years, there has been a vast development of high energy class lasers of the order of 100 J to kJ level which have potential applications in the field of science and technology. Many such systems use the gain media cooled at cryogenic temperatures which will help in enhancing the spectroscopic and thermo-optical properties. Nevertheless, parasitic effects like amplified spontaneous emission enhance and affect the overall efficiency. The best way to suppress this effect is to use cladding element attached to the gain material. Based on these facts, this work was focused on the systematic investigation of temperature dependent absorption of several materials doped with transition metals, which can be used as cladding, as laser gain material, or as passive Q-switching element. The Ti:sapphire, Cr:YAG, V:YAG, and Co:MALO samples were measured in temperature range from 80 K to 330 K by step of 50 K. Using Beer-Lambert law we estimated the absorption coefficient of these materials.

  16. Aerosol Absorption in the Atmosphere: Perspectives from Global Model, Ground-Based Measurements, and Field Observations

    NASA Technical Reports Server (NTRS)

    Chin, Mian; Dubovik, Oleg; Holben, Brent; Torres, Omar; Anderson, Tad; Quinn, Patricia; Ginoux, Paul

    2004-01-01

    Aerosol absorption in the atmosphere poses a major uncertainty in assessing the aerosol climate effects. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, and our limited knowledge of aerosol mixing state and optical properties. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt. We compare the model calculated total aerosol optical thickness, extinction, and absorption with those quantities from the ground-based sun photometer measurements from AERONET, satellite retrievals from the TOMS instrument, and field observations from ACE-Asia. We will examine the most sensitive factors in determining the aerosol absorption. and the consequences of assessing the aerosol radiative forcing and atmospheric heating associated with those factors.

  17. Aerosol Absorption in the Atmosphere: Perspectives from Global Model, Ground-Based Measurements, and Field Observations

    NASA Technical Reports Server (NTRS)

    Chin, Mian; Dubovik, Oleg; Holben, Brent; Anderson, Tad; Quinn, Patricia; Duncan, Bryan; Ginoux, Paul

    2003-01-01

    Aerosol absorption in the atmosphere poses a major uncertainty in assessing the aerosol climate effects. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, and our limited knowledge of aerosol mixing state and optical properties. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt. We compare the model calculated total aerosol optical thickness, extinction, and absorption with those quantities from the ground-based sun photometer measurements from AERONET at several different wavelengths and the field observations from ACE-Asia. We will examine what are the most sensitive factors in determining the aerosol absorption, and the consequences of assessing the aerosol radiative forcing and atmospheric heating associated with those factors.

  18. Aerosol Absorption in the Atmosphere: Perspectives from Global Model, Ground-Based Measurements, and Field Observations

    NASA Technical Reports Server (NTRS)

    Chin, Main; Dubovik, Oleg; Holben, Brent; Anderson, Tad; Quinn, Patricia; Duncan, Bryan; Ginoux, Paul

    2004-01-01

    Aerosol absorption in the atmosphere poses a major uncertainty in assessing the aerosol climate effects. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, and our limited knowledge of aerosol mixing state and optical properties. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt. We compare the model calculated total aerosol optical thickness, extinction, and absorption with those quantities from the ground-based sun photometer measurements from AERONET at several different wavelengths and the field observations from ACE-Asia. We will examine the most sensitive factors in determining the aerosol absorption, and the consequences of assessing the aerosol radiative forcing and atmospheric heating associated with those factors.

  19. Continuous optical measurement system of hemolysis during a photosensitization reaction using absorption spectrum

    NASA Astrophysics Data System (ADS)

    Hamada, R.; Ogawa, E.; Arai, T.

    2018-02-01

    To investigate hemolysis phenomena during a photosensitization reaction with the reaction condition continuously and simultaneously for a safety assessment of hemolysis side effect, we constructed an optical system to measure blood sample absorption spectrum during the reaction. Hemolysis degree might be under estimated in general evaluation methods because there is a constant oxygen pressure assumption in spite of oxygen depression take place. By investigating hemoglobin oxidation and oxygen desorption dynamics obtained from the contribution of the visible absorption spectrum and multiple regression analysis, both the hemolysis phenomena and its oxygen environment might be obtained with time. A 664 nm wavelength laser beam for the reaction excitation and 475-650 nm light beam for measuring the absorbance spectrum were arranged perpendicularly crossing. A quartz glass cuvette with 1×10 mm in dimensions for the spectrum measurement was located at this crossing point. A red blood cells suspension medium was arranged with low hematocrit containing 30 μg/ml talaporfin sodium. This medium was irradiated up to 40 J/cm2 . The met-hemoglobin, oxygenatedhemoglobin, and deoxygenated-hemoglobin concentrations were calculated by a multiple regression analysis from the measured spectra. We confirmed the met-hemoglobin concentration increased and oxygen saturation decreased with the irradiation time, which seems to indicate the hemolysis progression and oxygen consumption, respectively. By using our measuring system, the hemolysis progression seems to be obtained with oxygen environment information.

  20. Measurement of Glyoxal Using an Incoherent Broadband Cavity Enhanced Absorption Spectrometer

    NASA Astrophysics Data System (ADS)

    Washenfelder, R. A.; Langford, A. O.; Fuchs, H.; Brown, S. S.

    2008-12-01

    Glyoxal (CHOCHO) is the simplest alpha-dicarbonyl and one of the most prevalent dicarbonyls in the atmosphere. It is formed from the photooxidation of anthropogenic hydrocarbons (e.g. aromatics and acetylene), and is a minor oxidation product of isoprene and other biogenic species. Photolysis of glyoxal is a significant source of HOx (OH + HO2), and there is growing evidence that heterogeneous reactions of glyoxal play an important role in the formation of secondary organic aerosol. We present a novel technique for measurement of glyoxal using cavity enhanced absorption spectroscopy with a broadband light source (IBBCEAS). The output of a Xenon arc lamp is coupled into a 1 m optical cavity, and the spectrum of light exiting the cavity is recorded by a grating spectrometer with a charge- coupled device (CCD) array detector. The mirror reflectivity and effective path lengths are determined from the known Rayleigh scattering of He and dry zero air (N2 + O2). We use least-squares fitting with published reference spectra to simultaneous retrieve glyoxal, nitrogen dioxide (NO2), oxygen dimer (O4) and water (H2O) in the 441 to 469 nm spectral range. For a 1-min sampling time, the precision (±1σ) on signal for measurements of CHOCHO and NO2 is 29 pptv and 20 pptv respectively. We directly compare the incoherent broadband cavity enhanced absorption spectrometer to 404 and 532 nm cavity ringdown instruments for CHOCHO and NO2 detection, and find linear agreement over a wide range of concentrations. We present laboratory measurements of synthetic and real air samples containing CHOCHO and NO2, and discuss the potential for field measurements.

  1. 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

  2. Improving mass measurement accuracy in mass spectrometry based proteomics by combining open source tools for chromatographic alignment and internal calibration.

    PubMed

    Palmblad, Magnus; van der Burgt, Yuri E M; Dalebout, Hans; Derks, Rico J E; Schoenmaker, Bart; Deelder, André M

    2009-05-02

    Accurate mass determination enhances peptide identification in mass spectrometry based proteomics. We here describe the combination of two previously published open source software tools to improve mass measurement accuracy in Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS). The first program, msalign, aligns one MS/MS dataset with one FTICRMS dataset. The second software, recal2, uses peptides identified from the MS/MS data for automated internal calibration of the FTICR spectra, resulting in sub-ppm mass measurement errors.

  3. 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.

  4. Determination of the measurement threshold in gamma-ray spectrometry.

    PubMed

    Korun, M; Vodenik, B; Zorko, B

    2017-03-01

    In gamma-ray spectrometry the measurement threshold describes the lover boundary of the interval of peak areas originating in the response of the spectrometer to gamma-rays from the sample measured. In this sense it presents a generalization of the net indication corresponding to the decision threshold, which is the measurement threshold at the quantity value zero for a predetermined probability for making errors of the first kind. Measurement thresholds were determined for peaks appearing in the spectra of radon daughters 214 Pb and 214 Bi by measuring the spectrum 35 times under repeatable conditions. For the calculation of the measurement threshold the probability for detection of the peaks and the mean relative uncertainty of the peak area were used. The relative measurement thresholds, the ratios between the measurement threshold and the mean peak area uncertainty, were determined for 54 peaks where the probability for detection varied between some percent and about 95% and the relative peak area uncertainty between 30% and 80%. The relative measurement thresholds vary considerably from peak to peak, although the nominal value of the sensitivity parameter defining the sensitivity for locating peaks was equal for all peaks. At the value of the sensitivity parameter used, the peak analysis does not locate peaks corresponding to the decision threshold with the probability in excess of 50%. This implies that peaks in the spectrum may not be located, although the true value of the measurand exceeds the decision threshold. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. 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.

  6. Apparatus and method for measurement of weak optical absorptions by thermally induced laser pulsing

    DOEpatents

    Cremers, D.A.; Keller, R.A.

    1985-10-01

    The thermal lensing phenomenon is used as the basis for measurement of weak optical absorptions when a cell containing the sample to be investigated is inserted into a normally continuous-wave operation laser-pumped dye laser cavity for which the output coupler is deliberately tilted relative to intracavity circulating laser light, and pulsed laser output ensues, the pulsewidth of which can be related to the sample absorptivity by a simple algorithm or calibration curve. A minimum detection limit of less than 10[sup [minus]5] cm[sup [minus]1] has been demonstrated using this technique. 6 figs.

  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. Differential absorption and Raman lidar for water vapor profile measurements - A review

    NASA Technical Reports Server (NTRS)

    Grant, William B.

    1991-01-01

    Differential absorption lidar and Raman lidar have been applied to the range-resolved measurements of water vapor density for more than 20 years. Results have been obtained using both lidar techniques that have led to improved understanding of water vapor distributions in the atmosphere. This paper reviews the theory of the measurements, including the sources of systematic and random error; the progress in lidar technology and techniques during that period, including a brief look at some of the lidar systems in development or proposed; and the steps being taken to improve such lidar systems.

  9. Determining CDOM Absorption Spectra in Diverse Coastal Environments Using a Multiple Pathlength, Liquid Core Waveguide System. Measuring the Absorption of CDOM in the Field Using a Multiple Pathlength Liquid Waveguide System

    NASA Technical Reports Server (NTRS)

    Miller, Richard L.; Belz, Mathias; DelCastillo, Carlos; Trzaska, Rick

    2000-01-01

    We evaluated the accuracy, sensitivity and precision of a multiple pathlength, liquid core waveguide (MPLCW) system for measuring colored dissolved organic matter (CDOM) absorption in the UV-visible spectral range (370-700 nm). The MPLCW has four optical paths (2.0, 9.8, 49.3, and 204 cm) coupled to a single Teflon AF sample cell. Water samples were obtained from inland, coastal and ocean waters ranging in salinity from 0 to 36 PSU. Reference solutions for the MPLCW were made having a refractive index of the sample. CDOM absorption coefficients, a(sub CDOM), and the slope of the log-linearized absorption spectra, S, were compared with values obtained using a dual-beam spectrophotometer. Absorption of phenol red secondary standards measured by the MPLCW at 558 nm were highly correlated with spectrophotometer values (r > 0.99) and showed a linear response across all four pathlengths. Values of a(sub CDOM) measured using the MPLCW were virtually identical to spectrophotometer values over a wide range of concentrations. The dynamic range of a(sub CDOM) for MPLCW measurements was 0.002 - 231.5/m. At low CDOM concentrations (a(sub 370) < 0.1/m) spectrophotometric a(sub CDOM) were slightly greater than MPLCW values and showed larger fluctuations at longer wavelengths due to limitations in instrument precision. In contrast, MPLCW spectra followed an exponential to 600 nm for all samples. The maximum deviation in replicate MPLCW spectra was less than 0.001 absorbance units. The portability, sampling, and optical characteristics of a MPLCW system provide significant enhancements for routine CDOM absorption measurements in a broad range of natural waters.

  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. 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

  12. DOAS (differential optical absorption spectroscopy) urban pollution measurements

    NASA Astrophysics Data System (ADS)

    Stevens, Robert K.; Vossler, T. L.

    1991-05-01

    During July and August of 1990, a differential optical absorption spectrometer (DOAS) made by OPSIS Inc. was used to measure gaseous air pollutants over three separate open paths in Atlanta, GA. Over path 1 (1099 m) and path 2 (1824 m), ozone (03), sulfur dioxide (SO2) nitrogen dioxide (NO2), nitrous acid (HNO2) formaldehyde (HCHO), benzene, toluene, and o-xylene were measured. Nitric oxide (NO) and ammonia (NH3) were monitored over path 3 (143 m). The data quality and data capture depended on the compound being measured and the path over which it was measured. Data quality criteria for each compound were chosen such that the average relative standard deviation would be less than 25%. Data capture ranged from 43% for o-xylene for path 1 to 95% for ozone for path 2. Benzene, toluene, and o-xylene concentrations measured over path 2, which crossed over an interstate highway, were higher than concentrations measured over path 1, implicating emissions from vehicles on the highway as a significant source of these compounds. Federal Reference Method (FRN) instruments were located near the DOAS light receivers and measurements of 03, NO2, and NO were made concurrently with the DOAS. Correlation coefficients greater than 0.85 were obtained between the DOAS and FRM's; however, there was a difference between the mean values obtained by the two methods for 03 and NO. A gas chromatograph for measuring volatile organic compounds was operated next to the FRN's. Correlation coefficients of about 0.66 were obtained between the DOAS and GC measurements of benzene and o- xylene. However, the correlation coefficient between the DOAS and GC measurements of toluene averaged only 0.15 for the two DOAS measurement paths. The lack of correlation and other factors indicate the possibility of a localized source of toluene near the GC. In general, disagreements between the two measurement methods could be caused by atmospheric inhomogeneities or interferences in the DOAS and other methods.

  13. 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.

  14. absorption sensor for sensitive temperature and species measurements in high-temperature gases

    NASA Astrophysics Data System (ADS)

    Spearrin, R. M.; Ren, W.; Jeffries, J. B.; Hanson, R. K.

    2014-09-01

    A continuous-wave laser absorption diagnostic, based on the infrared CO2 bands near 4.2 and 2.7 μm, was developed for sensitive temperature and concentration measurements in high-temperature gas systems using fixed-wavelength methods. Transitions in the respective R-branches of both the fundamental υ 3 band (~2,350 cm-1) and combination υ 1 + υ 3 band (~3,610 cm-1) were chosen based on absorption line-strength, spectral isolation, and temperature sensitivity. The R(76) line near 2,390.52 cm-1 was selected for sensitive CO2 concentration measurements, and a detection limit of <5 ppm was achieved in shock tube kinetics experiments (~1,300 K). A cross-band, two-line thermometry technique was also established utilizing the R(96) line near 2,395.14 cm-1, paired with the R(28) line near 3,633.08 cm-1. This combination yields high temperature sensitivity (ΔE" = 3,305 cm-1) and expanded range compared with previous intra-band CO2 sensors. Thermometry performance was validated in a shock tube over a range of temperatures (600-1,800 K) important for combustion. Measured temperature accuracy was demonstrated to be better than 1 % over the entire range of conditions, with a standard error of ~0.5 % and µs temporal resolution.

  15. Development of a Coherent Differential Absorption Lidar for Range Resolved Atmospheric CO2 Measurements

    NASA Technical Reports Server (NTRS)

    Yu, Jirong; Petros, Mulgueta; Chen, Songsheng; Bai, Yingxin; Petzar, Paul J.; Trieu, Bo. C.; Koch, Grady J.; Beyon, Jeffery J.; Singh, Upendra N.

    2010-01-01

    A pulsed, 2-m coherent Differential Absorption Lidar (DIAL) / Integrated Path Differential Absorption (IPDA) transceiver, developed under the Laser Risk Reduction Program (LRRP) at NASA, is integrated into a fully functional lidar instrument. This instrument will measure atmospheric CO2 profiles (by DIAL) initially from a ground platform, and then be prepared for aircraft installation to measure the atmospheric CO2 column densities in the atmospheric boundary layer (ABL) and lower troposphere. The airborne prototype CO2 lidar can measure atmospheric CO2 column density in a range bin of 1km with better than 1.5% precision at horizontal resolution of less than 50km. It can provide the image of the pooling of CO2 in lowlying areas and performs nighttime mass balance measurements at landscape scale. This sensor is unique in its capability to study the vertical ABL-free troposphere exchange of CO2 directly. It will allow the investigators to pursue subsequent in science-driven deployments, and provides a unique tool for Active Sensing of CO2 Emissions over Night, Days, and Seasons (ASCENDS) validation that was strongly advocated in the recent ASCENDS Workshop.

  16. Ultra sound absorption measurements in rock samples at low temperatures

    NASA Technical Reports Server (NTRS)

    Herminghaus, C.; Berckhemer, H.

    1974-01-01

    A new technique, comparable with the reverberation method in room acoustics, is described. It allows Q-measurements at rock samples of arbitrary shape in the frequency range of 50 to 600 kHz in vacuum (.1 mtorr) and at low temperatures (+20 to -180 C). The method was developed in particular to investigate rock samples under lunar conditions. Ultrasound absorption has been measured at volcanics, breccia, gabbros, feldspar and quartz of different grain size and texture yielding the following results: evacuation raises Q mainly through lowering the humidity in the rock. In a dry compact rock, the effect of evacuation is small. With decreasing temperature, Q generally increases. Between +20 and -30 C, Q does not change much. With further decrease of temperature in many cases distinct anomalies appear, where Q becomes frequency dependent.

  17. Improvement in Suppression of Pulsed Nd:YAG Laser Light With Iodine Absorption Cells for Filtered Rayleigh Scattering Measurements

    NASA Technical Reports Server (NTRS)

    Seasholtz, Richard G.; Buggele, Alvin E

    1997-01-01

    Filtered Rayleigh scattering using iodine absorption cells is an effective technique for obtaining density, temperature, and velocity measurements in high speed confined flows. By tuning a single frequency laser to a strong iodine absorption line, stray scattered laser light can be greatly suppressed. For example, the minimum transmission predicted by an iodine absorption model calculation is less than 10(exp -5) at the 18788.44/cm line using a 200 mm absorption cell containing iodine vapor at 0.46 T. Measurements obtained by other researches using a CW Nd:YAG laser agree with the model calculations. However, measurements made by us and by others using Q-switched, injection-seeded, frequency doubled Nd:YAG lasers only show minimum transmission of about 3 x 10(exp -3). This greatly reduces the applicability of the filtered Rayleigh scattering technique using these lasers in experiments having large amounts of stray scattered laser light. The purposes of the present study are to characterize the spectrum of the excess light transmitted by the iodine cell and to make changes to the laser to reduce the transmitted laser light. Transmission data as a function of laser frequency for the iodine absorption line at 18788.44/cm are presented. A planar mirror Fabry-Perot interferometer was used to characterize the frequency spectrum of the light passed through the cell. Measurements taken with the laser tuned to the center of the iodine absorption line show the light transmitted through the iodine cell to have a component with a bandwidth of about 40 GHz. This is probably caused by other modes in the laser that exist in spite of the single frequency injection beam. A second broadband component was also observed, possibly caused by the laser flash lamps or by fluorescence. An intracavity etalon was installed in the laser oscillator cavity to suppress the 40 GHz component. Measurements taken with the etalon tuned to the injection frequency showed a reduction in the transmitted

  18. 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.

  19. Laser continuum source atomic absorption spectroscopy: Measuring the ground state with nanosecond resolution in laser-induced plasmas

    NASA Astrophysics Data System (ADS)

    Merten, Jonathan; Johnson, Bruce

    2018-01-01

    A new dual-beam atomic absorption technique is applied to laser-induced plasmas. The technique uses an optical parametric oscillator pseudocontinuum, producing emission that is both wider than the absorption line profile, but narrow enough to allow the use of an echelle spectrograph without order sorting. The dual-beam-in space implementation makes the technique immune to nonspecific attenuation of the probe beam and the structure of the pseudocontinuum. The potential for plasma diagnostics is demonstrated with spatially and temporally resolved measurements of magnesium metastable and lithium ground state optical depths in a laser-induced plasma under reduced pressure conditions. The lithium measurements further demonstrate the technique's potential for isotope ratio measurements.

  20. [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.

  1. Absorption/transmission measurements of PSAP particle-laden filters from the Biomass Burning Observation Project (BBOP) field campaign

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

    Presser, Cary; Nazarian, Ashot; Conny, Joseph M.

    Absorptivity measurements with a laser-heating approach, referred to as the laser-driven thermal reactor (LDTR), were carried out in the infrared and applied at ambient (laboratory) nonreacting conditions to particle-laden filters from a three-wavelength (visible) particle/soot absorption photometer (PSAP). Here, the particles were obtained during the Biomass Burning Observation Project (BBOP) field campaign. The focus of this study was to determine the particle absorption coefficient from field-campaign filter samples using the LDTR approach, and compare results with other commercially available instrumentation (in this case with the PSAP, which has been compared with numerous other optical techniques).

  2. Absorption/transmission measurements of PSAP particle-laden filters from the Biomass Burning Observation Project (BBOP) field campaign

    DOE PAGES

    Presser, Cary; Nazarian, Ashot; Conny, Joseph M.; ...

    2016-12-02

    Absorptivity measurements with a laser-heating approach, referred to as the laser-driven thermal reactor (LDTR), were carried out in the infrared and applied at ambient (laboratory) nonreacting conditions to particle-laden filters from a three-wavelength (visible) particle/soot absorption photometer (PSAP). Here, the particles were obtained during the Biomass Burning Observation Project (BBOP) field campaign. The focus of this study was to determine the particle absorption coefficient from field-campaign filter samples using the LDTR approach, and compare results with other commercially available instrumentation (in this case with the PSAP, which has been compared with numerous other optical techniques).

  3. Radionuclide measurements by accelerator mass spectrometry at Arizona

    NASA Technical Reports Server (NTRS)

    Jull, A. J. T.; Donahue, D. J.; Zabel, T. H.

    1986-01-01

    Over the past years, Tandem Accelerator Mass Spectrometry (TAMS) has become established as an important method for radionuclide analysis. In the Arizona system the accelerator is operated at a thermal voltage of 1.8MV for C-14 analysis, and 1.6 to 2MV for Be-10. Samples are inserted into a cesium sputter ion source in solid form. Negative ions sputtered from the target are accelerated to about 25kV, and the injection magnet selects ions of a particular mass. Ions of the 3+ charge state, having an energy of about 9MeV are selected by an electrostatic deflector, surviving ions pass through two magnets, where only ions of the desired mass-energy product are selected. The final detector is a combination ionization chamber to measure energy loss (and hence, Z), and a silicon surface-barrier detector which measures residual energy. After counting the trace iosotope for a fixed time, the injected ions are switched to the major isotope used for normalization. These ions are deflected into a Faraday cup after the first high-energy magnet. Repeated measurements of the isotope ratio of both sample and standards results in a measurement of the concentration of the radionuclide. Recent improvements in sample preparation for C-14 make preparation of high-beam current graphite targets directly from CO2 feasible. Except for some measurements of standards and backgrounds for Be-10 measurements to date have been on C-14. Although most results have been in archaeology and quaternary geology, studies have been expanded to include cosmogenic C-14 in meteorites. The data obtained so far tend to confirm the antiquity of Antarctic meteorites from the Allan Hills site. Data on three samples of Yamato meteorites gave terrestrial ages of between about 3 and 22 thousand years.

  4. Measured Wavelength-Dependent Absorption Enhancement of Internally Mixed Black Carbon with Absorbing and Nonabsorbing Materials.

    PubMed

    You, Rian; Radney, James G; Zachariah, Michael R; Zangmeister, Christopher D

    2016-08-02

    Optical absorption spectra of laboratory generated aerosols consisting of black carbon (BC) internally mixed with nonabsorbing materials (ammonium sulfate, AS, and sodium chloride, NaCl) and BC with a weakly absorbing brown carbon surrogate derived from humic acid (HA) were measured across the visible to near-IR (550 to 840 nm). Spectra were measured in situ using a photoacoustic spectrometer and step-scanning a supercontinuum laser source with a tunable wavelength and bandwidth filter. BC had a mass-specific absorption cross section (MAC) of 7.89 ± 0.25 m(2) g(-1) at λ = 550 nm and an absorption Ångström exponent (AAE) of 1.03 ± 0.09 (2σ). For internally mixed BC, the ratio of BC mass to the total mass of the mixture was chosen as 0.13 to mimic particles observed in the terrestrial atmosphere. The manner in which BC mixed with each material was determined from transmission electron microscopy (TEM). AS/BC and HA/BC particles were fully internally mixed, and the BC was both internally and externally mixed for NaCl/BC particles. The AS/BC, NaCl/BC, and HA/BC particles had AAEs of 1.43 ± 0.05, 1.34 ± 0.06, and 1.91 ± 0.05, respectively. The observed absorption enhancement of mixed BC relative to the pure BC was wavelength dependent for AS/BC and decreased from 1.5 at λ = 550 nm with increasing wavelength while the NaCl/BC enhancement was essentially wavelength independent. For HA/BC, the enhancement ranged from 2 to 3 and was strongly wavelength dependent. Removal of the HA absorption contribution to enhancement revealed that the enhancement was ≈1.5 and independent of wavelength.

  5. 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.

  6. 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.

  7. Atmospheric extinction in solar tower plants: absorption and broadband correction for MOR measurements

    NASA Astrophysics Data System (ADS)

    Hanrieder, N.; Wilbert, S.; Pitz-Paal, R.; Emde, C.; Gasteiger, J.; Mayer, B.; Polo, J.

    2015-08-01

    Losses of reflected Direct Normal Irradiance due to atmospheric extinction in concentrated solar tower plants can vary significantly with site and time. The losses of the direct normal irradiance between the heliostat field and receiver in a solar tower plant are mainly caused by atmospheric scattering and absorption by aerosol and water vapor concentration in the atmospheric boundary layer. Due to a high aerosol particle number, radiation losses can be significantly larger in desert environments compared to the standard atmospheric conditions which are usually considered in ray-tracing or plant optimization tools. Information about on-site atmospheric extinction is only rarely available. To measure these radiation losses, two different commercially available instruments were tested, and more than 19 months of measurements were collected and compared at the Plataforma Solar de Almería. Both instruments are primarily used to determine the meteorological optical range (MOR). The Vaisala FS11 scatterometer is based on a monochromatic near-infrared light source emission and measures the strength of scattering processes in a small air volume mainly caused by aerosol particles. The Optec LPV4 long-path visibility transmissometer determines the monochromatic attenuation between a light-emitting diode (LED) light source at 532 nm and a receiver and therefore also accounts for absorption processes. As the broadband solar attenuation is of interest for solar resource assessment for concentrated solar power (CSP), a correction procedure for these two instruments is developed and tested. This procedure includes a spectral correction of both instruments from monochromatic to broadband attenuation. That means the attenuation is corrected for the time-dependent solar spectrum which is reflected by the collector. Further, an absorption correction for the Vaisala FS11 scatterometer is implemented. To optimize the absorption and broadband correction (ABC) procedure, additional

  8. 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.

  9. A mid-infrared laser absorption sensor for carbon monoxide and temperature measurements

    NASA Astrophysics Data System (ADS)

    Vanderover, Jeremy

    A mid-infrared (mid-IR) absorption sensor based on quantum cascade laser (QCL) technology has been developed and demonstrated for high-temperature thermometry and carbon monoxide (CO) measurements in combustion environments. The sensor probes the high-intensity fundamental CO ro-vibrational band at 4.6 mum enabling sensitive measurement of CO and temperature at kHz acquisition rates. Because the sensor operates in the mid-IR CO fundamental band it is several orders of magnitude more sensitive than most of the previously developed CO combustion sensors which utilized absorption in the near-IR overtone bands and mature traditional telecommunications-based diode lasers. The sensor has been demonstrated and validated under operation in both scanned-wavelength absorption and wavelength-modulation spectroscopy (WMS) modes in room-temperature gas cell and high-temperature shock tube experiments with known and specified gas conditions. The sensor has also been demonstrated for CO and temperature measurements in an atmospheric premixed ethylene/air McKenna burner flat flame for a range of equivalence ratios (phi = 0.7-1.4). Demonstration of the sensor under scanned-wavelength direct absorption operation was performed in a room-temperature gas cell (297 K and 0.001-1 atm) allowing validation of the line strengths and line shapes predicted by the HITRAN 2004 spectroscopic database. Application of the sensor in scanned-wavelength mode, at 1-2 kHz acquisition bandwidths, to specified high-temperature shock-heated gases (950-3400 K, 1 atm) provided validation of the sensor for measurements under the high-temperature conditions found in combustion devices. The scanned-wavelength shock tube measurements yielded temperature determinations that deviated by only +/-1.2% (1-sigma deviation) with the reflected shock temperatures and CO mole fraction determinations that deviated by that specified CO mole fraction by only +/-1.5% (1-sigma deviation). These deviations are in fact smaller

  10. Quantitative Measurement of Protease-Activity with Correction of Probe Delivery and Tissue Absorption Effects

    PubMed Central

    Salthouse, Christopher D.; Reynolds, Fred; Tam, Jenny M.; Josephson, Lee; Mahmood, Umar

    2009-01-01

    Proteases play important roles in a variety of pathologies from heart disease to cancer. Quantitative measurement of protease activity is possible using a novel spectrally matched dual fluorophore probe and a small animal lifetime imager. The recorded fluorescence from an activatable fluorophore, one that changes its fluorescent amplitude after biological target interaction, is also influenced by other factors including imaging probe delivery and optical tissue absorption of excitation and emission light. Fluorescence from a second spectrally matched constant (non-activatable) fluorophore on each nanoparticle platform can be used to correct for both probe delivery and tissue absorption. The fluorescence from each fluorophore is separated using fluorescence lifetime methods. PMID:20161242

  11. Nonlinear absorption in single LaF3 and MgF2 layers at 193 nm measured by surface sensitive laser induced deflection technique

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

    Muehlig, Christian; Bublitz, Simon; Kufert, Siegfried

    2009-12-10

    We report nonlinear absorption data of LaF3 and MgF2 single layers at 193 nm. A highly surface sensitive measurement strategy of the laser induced deflection technique is introduced and applied to measure the absorption of highly transparent thin films independently of the substrate absorption. Linear absorptions k=({alpha}x{lambda})/4{pi} of 2x10{sup -4} and 8.5x10{sup -4} (LaF3) and 1.8x10{sup -4} and 6.9x10{sup -4} (MgF2) are found. Measured two photon absorption (TPA) coefficients are {beta}=1x10{sup -4} cm/W (LaF3), 1.8x10{sup -5}, and 5.8x10{sup -5} cm/W (MgF2). The TPA coefficients are several orders of magnitude higher than typical values for fluoride single crystals, which is likelymore » to result from sequential two step absorption processes.« less

  12. Absorption and Scattering of Aerosol measured onboard R/V Gisang1 over the Yellow Sea

    NASA Astrophysics Data System (ADS)

    Inae, K.; Lee, M.; Shin, B.; Ryoo, S.; Jung, J.; Kim, S. W.

    2017-12-01

    Absorption and scattering coefficient were measured onboard RV Gisang 1 over the Yellow Sea (covering 124° 127°E, 31° 38°N) during May June, 2016. BC concentration was analyzed at seven wavelengths (370, 470, 520, 590, 660, 880, and 950nm) every 1 minute by Aethalometer. Scattering coefficient was measured at three wavelengths (450, 550, and 750nm) every 5 minutes with Nephelometer. The mean absorption coefficient was 1.2 Mm-1 at 880nm and the mean scattering coefficient was 116Mm-1 at 550nm. Single scattering albedo(SSA) reached the maximum value of 3.0 at 700nm. The calculated mean scattering angstrom exponent(SAE) was 1.6 and absorbing angstrom exponent(AAE) was 1.1. The AAE and SAE were higher in aged Chinese plume.

  13. Comparative Analysis of Mass Spectral Similarity Measures on Peak Alignment for Comprehensive Two-Dimensional Gas Chromatography Mass Spectrometry

    PubMed Central

    2013-01-01

    Peak alignment is a critical procedure in mass spectrometry-based biomarker discovery in metabolomics. One of peak alignment approaches to comprehensive two-dimensional gas chromatography mass spectrometry (GC×GC-MS) data is peak matching-based alignment. A key to the peak matching-based alignment is the calculation of mass spectral similarity scores. Various mass spectral similarity measures have been developed mainly for compound identification, but the effect of these spectral similarity measures on the performance of peak matching-based alignment still remains unknown. Therefore, we selected five mass spectral similarity measures, cosine correlation, Pearson's correlation, Spearman's correlation, partial correlation, and part correlation, and examined their effects on peak alignment using two sets of experimental GC×GC-MS data. The results show that the spectral similarity measure does not affect the alignment accuracy significantly in analysis of data from less complex samples, while the partial correlation performs much better than other spectral similarity measures when analyzing experimental data acquired from complex biological samples. PMID:24151524

  14. Ambient Ionization Mass Spectrometry Measurement of Aminotransferase Activity

    NASA Astrophysics Data System (ADS)

    Yan, Xin; Li, Xin; Zhang, Chengsen; Xu, Yang; Cooks, R. Graham

    2017-06-01

    A change in enzyme activity has been used as a clinical biomarker for diagnosis and is useful in evaluating patient prognosis. Current laboratory measurements of enzyme activity involve multi-step derivatization of the reaction products followed by quantitative analysis of these derivatives. This study simplified the reaction systems by using only the target enzymatic reaction and directly detecting its product. A protocol using paper spray mass spectrometry for identifying and quantifying the reaction product has been developed. Evaluation of the activity of aspartate aminotransferase (AST) was chosen as a proof-of-principle. The volume of sample needed is greatly reduced compared with the traditional method. Paper spray has a desalting effect that avoids sprayer clogging problems seen when examining serum samples by nanoESI. This very simple method does not require sample pretreatment and additional derivatization reactions, yet it gives high quality kinetic data, excellent limits of detection (60 ppb from serum), and coefficients of variation <10% in quantitation. [Figure not available: see fulltext.

  15. Accurate mass measurement by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. II. Measurement of negative radical ions using porphyrin and fullerene standard reference materials.

    PubMed

    Shao, Zhecheng; Wyatt, Mark F; Stein, Bridget K; Brenton, A Gareth

    2010-10-30

    A method for the accurate mass measurement of negative radical ions by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS) is described. This is an extension to our previously described method for the accurate mass measurement of positive radical ions (Griffiths NW, Wyatt MF, Kean SD, Graham AE, Stein BK, Brenton AG. Rapid Commun. Mass Spectrom. 2010; 24: 1629). The porphyrin standard reference materials (SRMs) developed for positive mode measurements cannot be observed in negative ion mode, so fullerene and fluorinated porphyrin compounds were identified as effective SRMs. The method is of immediate practical use for the accurate mass measurement of functionalised fullerenes, for which negative ion MALDI-TOFMS is the principal mass spectrometry characterisation technique. This was demonstrated by the accurate mass measurement of six functionalised C(60) compounds. Copyright © 2010 John Wiley & Sons, Ltd.

  16. Aerosol column absorption measurements using co-located UV-MFRSR and AERONET CIMEL instruments

    NASA Astrophysics Data System (ADS)

    Krotkov, N.; Labow, G.; Herman, J.; Slusser, J.; Tree, R.; Janson, G.; Durham, B.; Eck, T.; Holben, B.

    2009-08-01

    Column aerosol absorption properties in the visible wavelengths are measured routinely in worldwide locations by NASA AERONET network (http://aeronet.gsfc.nasa.gov), while similar optical properties in UV can be derived from diffuse and global irradiance measurements measured with Multifilter Rotating Shadowband Radiometer (MFRSR) instruments of the USDA UV-MFRSR network (http://uvb.nrel.colostate.edu). To enable direct comparisons between the two techniques, we have modified our UV-MFRSR by replacing standard 300nm filter with 440nm filter used in AERONET network. The modified UV/VIS-MFRSR has been mostly deployed at AERONET calibration site at NASA GSFC in Greenbelt, MD, but also at number of field campaigns. While the UV-MSFRSR instrument is highly susceptible to calibration drifts, these drifts can be accurately assessed using co-located AERONET direct-sun AOT data. In 2006 quartz dome has been installed atop the MFRSR diffuser, which stabilized calibration drifts in 2007-2009. After correcting for remaining calibration changes, the AOT and single scattering albedo (SSA) at the UV wavelengths can be accurately inferred by fitting the measurements of global and diffuse atmospheric transmittances with the forward RT model at each UV-MFRSR spectral channel. Derived AOT and SSA at common wavelength 440nm by two different techniques are generally in good agreement. We also found that SSA becomes smaller in the UV wavelengths and has strong wavelength dependence across blue and near-UV spectral range. The measured enhanced UV absorption might suggest the presence of selectively UV absorbing aerosols. High spectral resolution SSA measurements in UV-VIS wavelengths are called for.

  17. 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.

  18. A Tale of two Cities: Photoacoustic and Aethalometer Measurements Comparisons of Light Absorption in Mexico City and Las Vegas, NV, USA

    NASA Astrophysics Data System (ADS)

    Paredes-Miranda, G.; Arnott, W. P.; Marley, N. A.; Gaffney, J. S.

    2007-05-01

    As part of the Megacity Impacts on Regional and Global Environments, MIRAGE-Mex deployment to Mexico City in the period of 30 days, March 2006, a suite of photoacoustic spectrometers (PAS; W. Arnott & G. Paredes), nephelometer scattering, and aetholemeter absorption instruments (N. Marley & J.Gaffney) were installed to measure at ground level the light absorption and scattering by aerosols at the urban site at Instituto Mexicano del Petroleo (Mexican Oil Institute, denoted by IMP). This IMP site gave in-situ characterization of the Mexico City plume under favorable wind conditions. The PAS used at IMP operates at 532 nm, and conveniently allowed for characterization of gaseous absorption at this wavelength as well. Light scattering measurements are accomplished within the PAS by the reciprocal nephelometery method. In the urban site the aerosol absorption coefficient typically varies between 20 and 180 Mm-1 during the course of the day and significant diurnal variation of the aerosol single scattering albedo was observed. The Las Vegas, NV site was located at East Charleston Street on January-February, 2003. In east Las Vegas typical westerly winds carry the city plume across the site. Comparisons of PAS aerosol light absorption and aetholemeter absorption measurements at 521 nm at both Las Vegas NV and Mexico City sites will be presented. We will also present a broad overview of the diurnal variation of the scattering and absorption as well as the single scattering albedo and fraction of absorption due to gases at the sites in relation to secondary aerosol formation.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. Analysis of Pulsed Lidar Measurements of Atmospheric CO2 Column Absorption During the ASCENDS 2009-2011 Airborne Campaigns

    NASA Technical Reports Server (NTRS)

    Abshire, J. B.; Weaver, C. J.; Riris, H.; Mao, J.; Sun, X; Allan, G. R.; Hasselbrack, W. E.; Browell, E. V.

    2012-01-01

    We have developed a pulsed lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's ASCENDS mission and have demonstrated the CO2 and O2 measurements from aircraft. Our technique uses two pulsed lasers allowing simultaneous measurement of a single CO2 absorption line near 1572 nm, O2 extinction in the Oxygen A-band, surface height and backscatter profile. The lasers are stepped in wavelength across the CO2 line and an O2 line doublet during the measurement. The column densities for the CO2 and O2 are estimated from the differential optical depths (DOD) of the scanned absorption lines via the IPDA technique. For the 2009 ASCENDS campaign we flew the CO2 lidar on a Lear-25 aircraft, and measured the absorption line shapes of the CO2 line using 20 wavelength samples per scan. Measurements were made at stepped altitudes from 3 to 12.6 km over the Lamont OK, central Illinois, North Carolina, and over the Virginia Eastern Shore. Although the received signal energies were weaker than expected for ASCENDS, clear CO2 line shapes were observed at all altitudes. Most flights had 5-6 altitude steps with 200-300 seconds of recorded measurements per step. We averaged every 10 seconds of measurements and used a cross-correlation approach to estimate the range to the scattering surface and the echo pulse energy at each wavelength. We then solved for the best-fit CO2 absorption line shape, and calculated the DOD of the fitted CO2 line, and computed its statistics at the various altitude steps. We compared them to CO2 optical depths calculated from spectroscopy based on HITRAN 2008 and the column number densities calculated from the airborne in-situ readings. The 2009 measurements have been analyzed and they were similar on all flights. The results show clear CO2 line shape and absorption signals, which follow the expected changes with aircraft altitude from 3 to 13 km. They showed the expected nearly the linear dependence of DOD vs altitude. The

  4. 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.

  5. 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.

  6. 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.

  7. Sensor for headspace pressure and H2O concentration measurements in closed vials by tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Cai, Tingdong; Wang, Guishi; Cao, Zhensong; Zhang, Weijun; Gao, Xiaoming

    2014-07-01

    The concentration of H2O and the pressure in the headspace of vials are simultaneously measured by a tunable diode laser sensor based on absorption spectroscopy techniques. The 7168.437 cm-1 spectral line of H2O is chosen as the sensing transition for its strong absorption strength and being reasonably far away from its neighboring molecular transitions. In order to prevent interference absorption by ambient water vapor in the room air, a difference between the measured signal and the referenced signal is used to calculate the pressure and H2O concentration in the headspace of vials, eliminating the need for inert gas purges and calibration with known gas. The validation of the sensor is conducted in a static vial, yielding an accuracy of 1.23% for pressure and 3.81% for H2O concentration. The sensitivity of the sensor is estimated to be about 2.5 Torr for pressure and 400 ppm for H2O concentration over a 3 cm absorption path length respectively. Accurate measurements for commercial freeze-dried products demonstrate the in-line applications of the sensor for the pharmaceutical industry.

  8. High Spectral Resolution Lidar Measurements Using an I2 Absorption Filter

    NASA Technical Reports Server (NTRS)

    Eloranta, E. W.; Piironen, P.

    1996-01-01

    The University of Wisconsin high spectral resolution lidar (HSRL) measures optical properties of the atmosphere by separating the Doppler-broadened molecular backscatter return from the unbroadened aerosol return. The HSRL was modified to use an I2 absorption cell The modified HSRL transmitter uses a continuously pumped, Q-switched, injection seeded, frequency doubled Nd:YAG laser operating at a 4 kHz pulse repetition rate. This laser is tunable over a 124 GHz frequency range by temperature tuning the seed laser under computer control.

  9. An IAEA multi-technique X-ray spectrometry endstation at Elettra Sincrotrone Trieste: benchmarking results and interdisciplinary applications.

    PubMed

    Karydas, Andreas Germanos; Czyzycki, Mateusz; Leani, Juan José; Migliori, Alessandro; Osan, Janos; Bogovac, Mladen; Wrobel, Pawel; Vakula, Nikita; Padilla-Alvarez, Roman; Menk, Ralf Hendrik; Gol, Maryam Ghahremani; Antonelli, Matias; Tiwari, Manoj K; Caliri, Claudia; Vogel-Mikuš, Katarina; Darby, Iain; Kaiser, Ralf Bernd

    2018-01-01

    The International Atomic Energy Agency (IAEA) jointly with the Elettra Sincrotrone Trieste (EST) operates a multipurpose X-ray spectrometry endstation at the X-ray Fluorescence beamline (10.1L). The facility has been available to external users since the beginning of 2015 through the peer-review process of EST. Using this collaboration framework, the IAEA supports and promotes synchrotron-radiation-based research and training activities for various research groups from the IAEA Member States, especially those who have limited previous experience and resources to access a synchrotron radiation facility. This paper aims to provide a broad overview about various analytical capabilities, intrinsic features and performance figures of the IAEA X-ray spectrometry endstation through the measured results. The IAEA-EST endstation works with monochromatic X-rays in the energy range 3.7-14 keV for the Elettra storage ring operating at 2.0 or 2.4 GeV electron energy. It offers a combination of different advanced analytical probes, e.g. X-ray reflectivity, X-ray absorption fine-structure measurements, grazing-incidence X-ray fluorescence measurements, using different excitation and detection geometries, and thereby supports a comprehensive characterization for different kinds of nanostructured and bulk materials.

  10. 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.

  11. Pulsed Lidar Measurements of Atmospheric CO2 Column Absorption and Range During the ASCENDS 2009-2011 Airborne Campaigns

    NASA Technical Reports Server (NTRS)

    Abshire, J. B.; Weaver, C. J.; Riris, H.; Mao, J.; Sun, X.; Allan, G. R.; Hasselbrack, W. E.; Browell, E. V.

    2012-01-01

    We have developed a pulsed lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's ASCENDS mission and have demonstrated the CO2 and O2 measurements from aircraft. Our technique uses two pulsed lasers allowing simultaneous measurement of a single CO2 absorption line near 1572 nm, O2 extinction in the Oxygen A-band, surface height and backscatter profile. The lasers are stepped in wavelength across the CO2 line and an O2 line doublet during the measurement. The column densities for the CO2 and O2 are estimated from the differential optical depths (DOD) of the scanned absorption lines via the IPDA technique. For the 2009 ASCENDS campaign we flew the CO2 lidar only on a Lear-25 aircraft, and measured the absorption line shapes of the CO2 line using 20 wavelength samples per scan. Measurements were made at stepped altitudes from 3 to 12.6 km over the Lamont OK, central Illinois, North Carolina, and over the Virginia Eastern Shore. Although the received signal energies were weaker than expected for ASCENDS, clear C02 line shapes were observed at all altitudes. Most flights had 5-6 altitude steps with 200-300 seconds of recorded measurements per step. We averaged every 10 seconds of measurements and used a cross-correlation approach to estimate the range to the scattering surface and the echo pulse energy at each wavelength. We then solved for the best-fit CO2 absorption line shape, and calculated the DOD of the fitted CO2 line, and computed its statistics at the various altitude steps. We compared them to CO2 optical depths calculated from spectroscopy based on HITRAN 2008 and the column number densities calculated from the airborne in-situ readings. The 2009 measurements have been analyzed in detail and they were similar on all flights. The results show clear CO2 line shape and absorption signals, which follow the expected changes with aircraft altitude from 3 to 13 km. They showed the expected nearly the linear dependence of DOD vs

  12. Influence of electrically induced refraction and absorption on the measurement of spin current by pockels effect in GaAs

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

    Liu, Houquan; She, Weilong, E-mail: shewl@mail.sysu.edu.cn

    2015-03-14

    The pockels effect could be utilized to measure spin current in semiconductors for linear electro-optic coefficient can be induced by spin current. When dc electric field is applied, the carriers will shift in k space, which could lead to the change of refraction and absorption coefficients. In this paper, we investigate the influence of the induced change of the refraction and absorption coefficients on the measurement of spin current by pockels effect in GaAs.

  13. 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.

  14. Optical re-injection in cavity-enhanced absorption spectroscopy

    PubMed Central

    Leen, J. Brian; O’Keefe, Anthony

    2014-01-01

    Non-mode-matched cavity-enhanced absorption spectrometry (e.g., cavity ringdown spectroscopy and integrated cavity output spectroscopy) is commonly used for the ultrasensitive detection of trace gases. These techniques are attractive for their simplicity and robustness, but their performance may be limited by the reflection of light from the front mirror and the resulting low optical transmission. Although this low transmitted power can sometimes be overcome with higher power lasers and lower noise detectors (e.g., in the near-infrared), many regimes exist where the available light intensity or photodetector sensitivity limits instrument performance (e.g., in the mid-infrared). In this article, we describe a method of repeatedly re-injecting light reflected off the front mirror of the optical cavity to boost the cavity's circulating power and deliver more light to the photodetector and thus increase the signal-to-noise ratio of the absorption measurement. We model and experimentally demonstrate the method's performance using off-axis cavity ringdown spectroscopy (OA-CRDS) with a broadly tunable external cavity quantum cascade laser. The power coupled through the cavity to the detector is increased by a factor of 22.5. The cavity loss is measured with a precision of 2 × 10−10 cm−1/\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}$\\sqrt {{\\rm Hz;}}$\\end{document} Hz ; an increase of 12 times over the standard off-axis configuration without reinjection and comparable to the best reported sensitivities in the mid-infrared. Finally, the re-injected CRDS system is used to measure the spectrum of several volatile organic compounds, demonstrating the improved ability to resolve weakly absorbing spectroscopic features. PMID:25273701

  15. Validation of double-pulse 1572 nm integrated path differential absorption lidar measurement of carbon dioxide

    NASA Astrophysics Data System (ADS)

    Du, Juan; Liu, Jiqiao; Bi, Decang; Ma, Xiuhua; Hou, Xia; Zhu, Xiaolei; Chen, Weibiao

    2018-04-01

    A ground-based double-pulse 1572 nm integrated path differential absorption (IPDA) lidar was developed for carbon dioxide (CO2) column concentrations measurement. The lidar measured the CO2 concentrations continuously by receiving the scattered echo signal from a building about 1300 m away. The other two instruments of TDLAS and in-situ CO2 analyzer measured the CO2 concentrations on the same time. A CO2 concentration measurement of 430 ppm with 1.637 ppm standard error was achieved.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Broadband cavity-enhanced absorption spectroscopy in the ultraviolet spectral region for measurements of nitrogen dioxide and formaldehyde

    NASA Astrophysics Data System (ADS)

    Washenfelder, R. A.; Attwood, A. R.; Flores, J. M.; Zarzana, K. J.; Rudich, Y.; Brown, S. S.

    2016-01-01

    Formaldehyde (CH2O) is the most abundant aldehyde in the atmosphere, and it strongly affects photochemistry through its photolysis. We describe simultaneous measurements of CH2O and nitrogen dioxide (NO2) using broadband cavity-enhanced absorption spectroscopy in the ultraviolet spectral region. The light source consists of a continuous-wave diode laser focused into a Xenon bulb to produce a plasma that emits high-intensity, broadband light. The plasma discharge is optically filtered and coupled into a 1 m optical cavity. The reflectivity of the cavity mirrors is 0.99930 ± 0.00003 (1- reflectivity = 700 ppm loss) at 338 nm, as determined from the known Rayleigh scattering of He and zero air. This mirror reflectivity corresponds to an effective path length of 1.43 km within the 1 m cell. We measure the cavity output over the 315-350 nm spectral region using a grating monochromator and charge-coupled device array detector. We use published reference spectra with spectral fitting software to simultaneously retrieve CH2O and NO2 concentrations. Independent measurements of NO2 standard additions by broadband cavity-enhanced absorption spectroscopy and cavity ring-down spectroscopy agree within 2 % (slope for linear fit = 1.02 ± 0.03 with r2 = 0.998). Standard additions of CH2O measured by broadband cavity-enhanced absorption spectroscopy and calculated based on flow dilution are also well correlated, with r2 = 0.9998. During constant mixed additions of NO2 and CH2O, the 30 s measurement precisions (1σ) of the current configuration were 140 and 210 pptv, respectively. The current 1 min detection limit for extinction measurements at 315-350 nm provides sufficient sensitivity for measurement of trace gases in laboratory experiments and ground-based field experiments. Additionally, the instrument provides highly accurate, spectroscopically based trace gas detection that may complement higher precision techniques based on non

  1. Mass spectrometry of long-lived radionuclides

    NASA Astrophysics Data System (ADS)

    Becker, Johanna Sabine

    2003-10-01

    The capability of determining element concentrations at the trace and ultratrace level and isotope ratios is a main feature of inorganic mass spectrometry. The precise and accurate determination of isotope ratios of long-lived natural and artificial radionuclides is required, e.g. for their environmental monitoring and health control, for studying radionuclide migration, for age dating, for determining isotope ratios of radiogenic elements in the nuclear industry, for quality assurance and determination of the burn-up of fuel material in a nuclear power plant, for reprocessing plants, nuclear material accounting and radioactive waste control. Inorganic mass spectrometry, especially inductively coupled plasma mass spectrometry (ICP-MS) as the most important inorganic mass spectrometric technique today, possesses excellent sensitivity, precision and good accuracy for isotope ratio measurements and practically no restriction with respect to the ionization potential of the element investigated—therefore, thermal ionization mass spectrometry (TIMS), which has been used as the dominant analytical technique for precise isotope ratio measurements of long-lived radionuclides for many decades, is being replaced increasingly by ICP-MS. In the last few years instrumental progress in improving figures of merit for the determination of isotope ratio measurements of long-lived radionuclides in ICP-MS has been achieved by the application of a multiple ion collector device (MC-ICP-MS) and the introduction of the collision cell interface in order to dissociate disturbing argon-based molecular ions, to reduce the kinetic energy of ions and neutralize the disturbing noble gas ions (e.g. of 129Xe + for the determination of 129I). The review describes the state of the art and the progress of different inorganic mass spectrometric techniques such as ICP-MS, laser ablation ICP-MS vs. TIMS, glow discharge mass spectrometry, secondary ion mass spectrometry, resonance ionization mass

  2. In situ combustion measurements of H2O and temperature near 2.5 µm using tunable diode laser absorption

    NASA Astrophysics Data System (ADS)

    Farooq, Aamir; Jeffries, Jay B.; Hanson, Ronald K.

    2008-07-01

    In situ combustion measurements of water vapor concentration and gas temperature were carried out with a new tunable diode laser sensor near 2.5 µm. Recent availability of room-temperature semiconductor diode lasers operating at longer wavelengths provides access to fundamental vibrational bands (ν1 and ν3) of H2O. These bands have stronger absorption line strength compared to the overtone (2ν1, 2ν3) and combination (ν1 + ν3) vibrational bands in the near-infrared region probed previously with telecommunication diode lasers. The absorption transitions of H2O vapor in the 2.5-3.0 µm region are systematically analyzed via spectral simulation, and optimal spectral line pairs are selected for combustion measurements in the temperature range of 1000-2500 K. Fundamental spectroscopic parameters (line strength, line position and line-broadening coefficients) of the selected transitions are determined via laboratory measurements in a heated cell. Absorption measurements of H2O concentration and temperature are then made in a laboratory flat-flame burner to illustrate the potential of this sensor for sensitive and accurate measurements in combustion gases with short optical path lengths.

  3. 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.

  4. 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.

  5. 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.

  6. Improvement of scattering correction for in situ coastal and inland water absorption measurement using exponential fitting approach

    NASA Astrophysics Data System (ADS)

    Ye, Huping; Li, Junsheng; Zhu, Jianhua; Shen, Qian; Li, Tongji; Zhang, Fangfang; Yue, Huanyin; Zhang, Bing; Liao, Xiaohan

    2017-10-01

    The absorption coefficient of water is an important bio-optical parameter for water optics and water color remote sensing. However, scattering correction is essential to obtain accurate absorption coefficient values in situ using the nine-wavelength absorption and attenuation meter AC9. Establishing the correction always fails in Case 2 water when the correction assumes zero absorption in the near-infrared (NIR) region and underestimates the absorption coefficient in the red region, which affect processes such as semi-analytical remote sensing inversion. In this study, the scattering contribution was evaluated by an exponential fitting approach using AC9 measurements at seven wavelengths (412, 440, 488, 510, 532, 555, and 715 nm) and by applying scattering correction. The correction was applied to representative in situ data of moderately turbid coastal water, highly turbid coastal water, eutrophic inland water, and turbid inland water. The results suggest that the absorption levels in the red and NIR regions are significantly higher than those obtained using standard scattering error correction procedures. Knowledge of the deviation between this method and the commonly used scattering correction methods will facilitate the evaluation of the effect on satellite remote sensing of water constituents and general optical research using different scattering-correction methods.

  7. Double-pulse 1.57  μm integrated path differential absorption lidar ground validation for atmospheric carbon dioxide measurement.

    PubMed

    Du, Juan; Zhu, Yadan; Li, Shiguang; Zhang, Junxuan; Sun, Yanguang; Zang, Huaguo; Liu, Dan; Ma, Xiuhua; Bi, Decang; Liu, Jiqiao; Zhu, Xiaolei; Chen, Weibiao

    2017-09-01

    A ground-based double-pulse integrated path differential absorption (IPDA) instrument for carbon dioxide (CO 2 ) concentration measurements at 1572 nm has been developed. A ground experiment was implemented under different conditions with a known wall located about 1.17 km away acting as the scattering hard target. Off-/offline testing of a laser transmitter was conducted to estimate the instrument systematic and random errors. Results showed a differential absorption optical depth (DAOD) offset of 0.0046 existing in the instrument. On-/offline testing was done to achieve the actual DAOD resulting from the CO 2 absorption. With 18 s pulses average, it demonstrated that a CO 2 concentration measurement of 432.71±2.42  ppm with 0.56% uncertainty was achieved. The IPDA ranging led to a measurement uncertainty of 1.5 m.

  8. Developing and Validating Field Measurement Scales for Absorptive Capacity and Experienced Community of Practice

    ERIC Educational Resources Information Center

    Cadiz, David; Sawyer, John E.; Griffith, Terri L.

    2009-01-01

    Research on knowledge transfer in organizations has been hampered by the lack of tools yielding valid scores for studying critical constructs in concert. The authors developed survey measures of absorptive capacity (the ability to transform new knowledge into usable knowledge) and experienced community of practice (the extent to which a person is…

  9. Atmospheric solar absorption measurements in the 9 to 11 mu m region using a diode laser heterodyne spectrometer

    NASA Technical Reports Server (NTRS)

    Harward, C. N.; Hoell, J. M., Jr.

    1980-01-01

    A tunable diode laser heterodyne radiometer was developed for ground-based measurements of atmospheric solar absorption spectra in the 8 to 12 microns spectral range. The performance and operating characteristics of this Tunable Infrared Heterodyne Radiometer (TIHR) are discussed along with atmospheric solar absorption spectra of HNO3, O3, CO2, and H2O in the 9 to 11 microns spectral region.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Measuring Food Intake and Nutrient Absorption in Caenorhabditis elegans

    PubMed Central

    Gomez-Amaro, Rafael L.; Valentine, Elizabeth R.; Carretero, Maria; LeBoeuf, Sarah E.; Rangaraju, Sunitha; Broaddus, Caroline D.; Solis, Gregory M.; Williamson, James R.; Petrascheck, Michael

    2015-01-01

    Caenorhabditis elegans has emerged as a powerful model to study the genetics of feeding, food-related behaviors, and metabolism. Despite the many advantages of C. elegans as a model organism, direct measurement of its bacterial food intake remains challenging. Here, we describe two complementary methods that measure the food intake of C. elegans. The first method is a microtiter plate-based bacterial clearing assay that measures food intake by quantifying the change in the optical density of bacteria over time. The second method, termed pulse feeding, measures the absorption of food by tracking de novo protein synthesis using a novel metabolic pulse-labeling strategy. Using the bacterial clearance assay, we compare the bacterial food intake of various C. elegans strains and show that long-lived eat mutants eat substantially more than previous estimates. To demonstrate the applicability of the pulse-feeding assay, we compare the assimilation of food for two C. elegans strains in response to serotonin. We show that serotonin-increased feeding leads to increased protein synthesis in a SER-7-dependent manner, including proteins known to promote aging. Protein content in the food has recently emerged as critical factor in determining how food composition affects aging and health. The pulse-feeding assay, by measuring de novo protein synthesis, represents an ideal method to unequivocally establish how the composition of food dictates protein synthesis. In combination, these two assays provide new and powerful tools for C. elegans research to investigate feeding and how food intake affects the proteome and thus the physiology and health of an organism. PMID:25903497

  15. Direct measurements of unimolecular and bimolecular reaction kinetics of the Criegee intermediate (CH 3) 2COO

    DOE PAGES

    Chhantyal-Pun, Rabi; Welz, Oliver; Savee, John D.; ...

    2016-10-18

    Here, the Criegee intermediate acetone oxide, (CH 3) 2COO, is formed by laser photolysis of 2,2-diiodopropane in the presence of O 2 and characterized by synchrotron photoionization mass spectrometry and by cavity ring-down ultraviolet absorption spectroscopy. The rate coefficient of the reaction of the Criegee intermediate with SO 2 was measured using photoionization mass spectrometry and pseudo-first-order methods to be (7.3 ± 0.5) × 10 –11 cm 3 s –1 at 298 K and 4 Torr and (1.5 ± 0.5) × 10 –10 cm 3 s –1 at 298 K and 10 Torr (He buffer). These values are similar tomore » directly measured rate coefficients of anti-CH 3CHOO with SO 2, and in good agreement with recent UV absorption measurements. The measurement of this reaction at 293 K and slightly higher pressures (between 10 and 100 Torr) in N 2 from cavity ring-down decay of the ultraviolet absorption of (CH 3) 2COO yielded even larger rate coefficients, in the range (1.84 ± 0.12) × 10 –10 to (2.29 ± 0.08) × 10 –10 cm 3 s –1. Photoionization mass spectrometry measurements with deuterated acetone oxide at 4 Torr show an inverse deuterium kinetic isotope effect, kH/kD = (0.53 ± 0.06), for reactions with SO 2, which may be consistent with recent suggestions that the formation of an association complex affects the rate coefficient. The reaction of (CD3)2COO with NO2 has a rate coefficient at 298 K and 4 Torr of (2.1 ± 0.5) × 10 –12 cm 3 s –1 (measured with photoionization mass spectrometry), again similar to rate for the reaction of anti-CH 3CHOO with NO 2. Cavity ring-down measurements of the acetone oxide removal without added reagents display a combination of first- and second-order decay kinetics, which can be deconvolved to derive values for both the self-reaction of (CH 3) 2COO and its unimolecular thermal decay. The inferred unimolecular decay rate coefficient at 293 K, (305 ± 70) s –1, is similar to determinations from ozonolysis. The present measurements confirm the large

  16. UV laser long-path absorption spectroscopy

    NASA Technical Reports Server (NTRS)

    Dorn, Hans-Peter; Brauers, Theo; Neuroth, Rudolf

    1994-01-01

    Long path Differential Optical Absorption Spectroscopy (DOAS) using a picosecond UV laser as a light source was developed in our institute. Tropospheric OH radicals are measured by their rotational absorption lines around 308 nm. The spectra are obtained using a high resolution spectrograph. The detection system has been improved over the formerly used optomechanical scanning device by application of a photodiode array which increased the observed spectral range by a factor of 6 and which utilizes the light much more effectively leading to a considerable reduction of the measurement time. This technique provides direct measurements of OH because the signal is given by the product of the absorption coefficient and the OH concentration along the light path according to Lambert-Beers law. No calibration is needed. Since the integrated absorption coefficient is well known the accuracy of the measurement essentially depends on the extent to which the OH absorption pattern can be detected in the spectra. No interference by self generated OH radicals in the detection lightpath has been observed. The large bandwidth (greater than 0.15 nm) and the high spectral resolution (1.5 pm) allows absolute determination of interferences by other trace gas absorptions. The measurement error is directly accessible from the absorption-signal to baseline-noise ratio in the spectra. The applicability of the method strongly depends on visibility. Elevated concentrations of aerosols lead to considerable attenuation of the laser light which reduces the S/N-ratio. In the moderately polluted air of Julich, where we performed a number of OH measurement spectra. In addition absorption features of unidentified species were frequently detected. A quantitative deconvolution even of the known species is not easy to achieve and can leave residual structures in the spectra. Thus interferences usually increase the noise and deteriorate the OH detection sensitivity. Using diode arrays for sensitive

  17. Near simultaneous measurements of NO2 and NO3 over tropics by ground-based absorption spectroscopy

    NASA Technical Reports Server (NTRS)

    Lal, M.; Chakrabarty, D. K.; Sidhu, J. S.; Das, S. R.

    1994-01-01

    The present study concentrates on measurements of NO2 and NO3. NO2 has been measured during twilight period using zenith sky absorption spectrometric technique in the 436 to 448 nm region. NO3 has been measured during night time using direct moon as a source of light in the 655 to 667 nm region. These measurements have been taken at low latitude station, Ahmedabad (23 deg N, 76 deg E), India for the past two years.

  18. Nuclear Forensics: Measurements of Uranium Oxides Using Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS)

    DTIC Science & Technology

    2010-03-01

    Isotope Ratio Analysis of Actinides , Fission Products, and Geolocators by High- efficiency Multi-collector Thermal Ionization Mass Spectrometry...Information, 1999. Hou, Xiaolin, and Per Roos. “ Critical Comparison of radiometric and Mass Spectrometric Methods for the Determination of...NUCLEAR FORENSICS: MEASUREMENTS OF URANIUM OXIDES USING TIME-OF-FLIGHT SECONDARY ION MASS

  19. 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.

  20. 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.

  1. Pressure measurement in supersonic air flow by differential absorptive laser-induced thermal acoustics.

    PubMed

    Hart, Roger C; Herring, G C; Balla, R Jeffrey

    2007-06-15

    Nonintrusive, off-body flow barometry in Mach 2 airflow has been demonstrated in a large-scale supersonic wind tunnel using seedless laser-induced thermal acoustics (LITA). The static pressure of the gas flow is determined with a novel differential absorption measurement of the ultrasonic sound produced by the LITA pump process. Simultaneously, the streamwise velocity and static gas temperature of the same spatially resolved sample volume were measured with this nonresonant time-averaged LITA technique. Mach number, temperature, and pressure have 0.2%, 0.4%, and 4% rms agreement, respectively, in comparison with known free-stream conditions.

  2. Pressure Measurement in Supersonic Air Flow by Differential Absorptive Laser-Induced Thermal Acoustics

    NASA Technical Reports Server (NTRS)

    Hart, Roger C.; Herring, Gregory C.; Balla, Robert J.

    2007-01-01

    Nonintrusive, off-body flow barometry in Mach-2 airflow has been demonstrated in a large-scale supersonic wind tunnel using seedless laser-induced thermal acoustics (LITA). The static pressure of the gas flow is determined with a novel differential absorption measurement of the ultrasonic sound produced by the LITA pump process. Simultaneously, stream-wise velocity and static gas temperature of the same spatially-resolved sample volume were measured with this nonresonant time-averaged LITA technique. Mach number, temperature and pressure have 0.2%, 0.4%, and 4% rms agreement, respectively, in comparison with known free-stream conditions.

  3. Laboratory Measurements of Mass Specific Absorption Spectra for Suites of Black Carbon-like, Biomass Burning and Mineral Dust Aerosols

    NASA Astrophysics Data System (ADS)

    Radney, J.; Zangmeister, C.

    2017-12-01

    Light-absorbing atmospheric aerosols can be grouped into three categories: black carbon (BC), brown carbon (BrC) or mineral dust (MD). In many cases, the absorption of these species is best quantified using a mass-specific absorption cross section (MAC) since the particles are in the Rayleigh regime (BC) or optically thin (BrC and MD); notably, MAC values are both traceable to the SI and transferrable between photoacoustic spectroscopy and filter-based absorption measurements. Here, we present laboratory measurements of MAC for all three light-absorbing aerosol classes. Particles were size- and mass-selected using a differential mobility analyzer and aerosol particle mass analyzer, respectively, with absorption coefficients (αabs) and number concentrations (N) being measured by a broadband photoacoustic spectrometer and condensation particle counter, respectively. This suite of instrumentation allows for direct quantification of MAC from the measured parameters (MAC = αabs/Nmp). Further, the measurements contained > 8 data points spanning λ = 405 nm to 840 nm allowing for spectral curvatures (i.e. the Absorption Angstrom Exponent or AAE) to be fit from many data points versus the more common 2-point interpolations. For the carbonaceous, BC-like aerosols - five samples generated from flames, spark discharge soot (i.e. fullerene soot), graphene, reduced graphene oxide (rGO), and fullerene (C60) - we found: 1) measured MAC ranged between 2.4 m2 g-1 and 8.6 m2 g-1 at λ = 550 nm, 2) most AAEs ranged between 0.5 and 1.3; C60 AAE was 7.5 ± 0.9 and 3) MAC spectra were dependent on fuel type and formation conditions. For BrC particles generated from smoldering combustion of 3 hardwood (Oak, Hickory and Mesquite) and 3 softwood species (Western redcedar, Blue spruce and Baldcypress), we found: 1) median MAC values ranged from 1.4 x 10-2 m2 g-1 to 7.9 x 10-2 m2 g-1 at λ = 550 nm, 2) AAE values ranged between 3.5 and 6.2, and 3) Oak, Western redcedar and Blue spruce

  4. In-Line Capacitance Sensor for Real-Time Water Absorption Measurements

    NASA Technical Reports Server (NTRS)

    Nurge, Mark A.; Perusich, Stephen A.

    2010-01-01

    A capacitance/dielectric sensor was designed, constructed, and used to measure in real time the in-situ water concentration in a desiccant water bed. Measurements were carried out with two experimental setups: (1) passing nitrogen through a humidity generator and allowing the gas stream to become saturated at a measured temperature and pressure, and (2) injecting water via a syringe pump into a nitrogen stream. Both water vapor generating devices were attached to a downstream vertically-mounted water capture bed filled with 19.5 g of Moisture Gone desiccant. The sensor consisted of two electrodes: (1) a 1/8" dia stainless steel rod placed in the middle of the bed and (2) the outer shell of the stainless steel bed concentric with the rod. All phases of the water capture process (background, heating, absorption, desorption, and cooling) were monitored with capacitance. The measured capacitance was found to vary linearly with the water content in the bed at frequencies above 100 kHz indicating dipolar motion dominated the signal; below this frequency, ionic motion caused nonlinearities in the water concentration/capacitance relationship. The desiccant exhibited a dielectric relaxation whose activation energy was lowered upon addition of water indicating either a less hindered rotational motion or crystal reorientation.

  5. [Shock absorption of mouthguard materials--influence of temperature conditions and shore hardness on shock absorption].

    PubMed

    Tomita, Takashi; Tsukimura, Naoki; Ohno, Shigeru; Umekawa, Yoshitada; Sawano, Muneyuki; Fujimoto, Toshiki; Takamura, Masaaki; Majima, Aiko; Katakura, Yuusuke; Kurata, Akemi; Ohyama, Tetsuo; Ishigami, Tomohiko

    2006-04-01

    To consider changes in the physical properties of mouthguard materials with the change of temperature, shock-absorbing examination and Shore hardness measurement of existing MG materials and other elastic materials were carried out. Both examinations were done under two temperature conditions: at room temperature (25 degrees C) and simulated intraoral temperature (37 degrees C). In addition, a comparative study of the relation between Shore hardness and shock absorption of the materials was made. A self-made drop impact machine was used for the shock-absorbing examination. The thickness of a sample was assumed to be 3 mm. The loading was applied by dropping 3 kinds of steel ball, phi 10 mm (4.0 g), phi 15 mm (13.7 g), and phi 20 mm (32.6 g) from a height of 60 cm. The shock absorption of all materials was compared by the maximum impact force. Shore hardness was measured based on the JIS standard. The shock absorption of each material showed a different tendency depending on the loading condition. Furthermore, the shock absorption of the same material showed different results depending on the temperature condition. Shore hardness measurements tended to show low values with the condition of 37 degrees C for all materials. From the relation between shock absorption and Shore hardness, it was confirmed that there is a correlation between hardness and the maximum impact force in the materials that showed shock absorption by elastic deformation. Some materials showed high shock absorption compared with existing MG materials.

  6. Analytical aspects of hydrogen exchange mass spectrometry

    PubMed Central

    Engen, John R.; Wales, Thomas E.

    2016-01-01

    The analytical aspects of measuring hydrogen exchange by mass spectrometry are reviewed. The nature of analytical selectivity in hydrogen exchange is described followed by review of the analytical tools required to accomplish fragmentation, separation, and the mass spectrometry measurements under restrictive exchange quench conditions. In contrast to analytical quantitation that relies on measurements of peak intensity or area, quantitation in hydrogen exchange mass spectrometry depends on measuring a mass change with respect to an undeuterated or deuterated control, resulting in a value between zero and the maximum amount of deuterium that could be incorporated. Reliable quantitation is a function of experimental fidelity and to achieve high measurement reproducibility, a large number of experimental variables must be controlled during sample preparation and analysis. The method also reports on important qualitative aspects of the sample, including conformational heterogeneity and population dynamics. PMID:26048552

  7. Spectral Absorption Properties of Atmospheric Aerosols

    NASA Technical Reports Server (NTRS)

    Bergstrom, R. W.; Pilewskie, P.; Russell, P. B.; Redemann, J.; Bond, T. C.; Quinn, P. K.; Sierau, B.

    2007-01-01

    We have determined the solar spectral absorption optical depth of atmospheric aerosols for specific case studies during several field programs (three cases have been reported previously; two are new results). We combined airborne measurements of the solar net radiant flux density and the aerosol optical depth with a detailed radiative transfer model for all but one of the cases. The field programs (SAFARI 2000, ACE Asia, PRIDE, TARFOX, INTEX-A) contained aerosols representing the major absorbing aerosol types: pollution, biomass burning, desert dust and mixtures. In all cases the spectral absorption optical depth decreases with wavelength and can be approximated with a power-law wavelength dependence (Absorption Angstrom Exponent or AAE). We compare our results with other recent spectral absorption measurements and attempt to briefly summarize the state of knowledge of aerosol absorption spectra in the atmosphere. We discuss the limitations in using the AAE for calculating the solar absorption. We also discuss the resulting spectral single scattering albedo for these cases.

  8. Precise dielectric property measurements and E-field probe calibration for specific absorption rate measurements using a rectangular waveguide

    PubMed Central

    Hakim, B M; Beard, B B; Davis, C C

    2018-01-01

    Specific absorption rate (SAR) measurements require accurate calculations of the dielectric properties of tissue-equivalent liquids and associated calibration of E-field probes. We developed a precise tissue-equivalent dielectric measurement and E-field probe calibration system. The system consists of a rectangular waveguide, electric field probe, and data control and acquisition system. Dielectric properties are calculated using the field attenuation factor inside the tissue-equivalent liquid and power reflectance inside the waveguide at the air/dielectric-slab interface. Calibration factors were calculated using isotropicity measurements of the E-field probe. The frequencies used are 900 MHz and 1800 MHz. The uncertainties of the measured values are within ±3%, at the 95% confidence level. Using the same waveguide for dielectric measurements as well as calibrating E-field probes used in SAR assessments eliminates a source of uncertainty. Moreover, we clearly identified the system parameters that affect the overall uncertainty of the measurement system. PMID:29520129

  9. A three-color absorption/scattering imaging technique for simultaneous measurements on distributions of temperature and fuel concentration in a spray

    NASA Astrophysics Data System (ADS)

    Qi, Wenyuan; Zhang, Yuyin

    2018-04-01

    A three-color imaging technique was proposed for simultaneous measurements on distributions of fuel/air mixture temperature and fuel vapor/liquid concentrations in evaporating sprays. The idea is based on that the vapor concentration is proportional to the absorption of vapor to UV light, the liquid-phase concentration is related to the light extinction due to scattering of droplet to visible light, and the mixture temperature can be correlated to the absorbance ratio at two absorbing wavelengths or narrow bands. For verifying the imaging system, the molar absorption coefficients of p-xylene at the three narrow bands, which were centered respectively at 265, 289, and 532 nm with FWHM of 10 nm, were measured in a specially designed calibration chamber at different temperatures (423-606 K) and pressure of 3.6 bar. It was found that the ratio of the molar absorption coefficients of p-xylene at the two narrow bands centered at the two UV wavelengths is sensitive to the mixture temperature. On the other hand, the distributions of fuel vapor/liquid concentrations can be obtained by use of absorbance due to ultraviolet absorption of vapor and visible light scattering of droplets. Combining these two methods, a simultaneous measurement on distributions of mixture temperature and fuel vapor/liquid concentrations can be realized. In addition, the temperature field obtained from the ratio of the two absorbing narrow bands can be further used to improve the measurement accuracy of vapor/liquid concentrations, because the absorption coefficients depend on temperature. This diagnostic was applied to an evaporating spray inside a high-temperature and high-pressure constant volume chamber.

  10. Quantification of 2D elemental distribution maps of intermediate-thick biological sections by low energy synchrotron μ-X-ray fluorescence spectrometry

    NASA Astrophysics Data System (ADS)

    Kump, P.; Vogel-Mikuš, K.

    2018-05-01

    Two fundamental-parameter (FP) based models for quantification of 2D elemental distribution maps of intermediate-thick biological samples by synchrotron low energy μ-X-ray fluorescence spectrometry (SR-μ-XRF) are presented and applied to the elemental analysis in experiments with monochromatic focused photon beam excitation at two low energy X-ray fluorescence beamlines—TwinMic, Elettra Sincrotrone Trieste, Italy, and ID21, ESRF, Grenoble, France. The models assume intermediate-thick biological samples composed of measured elements, the sources of the measurable spectral lines, and by the residual matrix, which affects the measured intensities through absorption. In the first model a fixed residual matrix of the sample is assumed, while in the second model the residual matrix is obtained by the iteration refinement of elemental concentrations and an adjusted residual matrix. The absorption of the incident focused beam in the biological sample at each scanned pixel position, determined from the output of a photodiode or a CCD camera, is applied as a control in the iteration procedure of quantification.

  11. 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.

  12. 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%.

  13. 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

  14. Measurement of ²²⁶Ra in soil from oil field: advantages of γ-ray spectrometry and application to the IAEA-448 CRM.

    PubMed

    Ceccatelli, A; Katona, R; Kis-Benedek, G; Pitois, A

    2014-05-01

    The analytical performance of gamma-ray spectrometry for the measurement of (226)Ra in TENORM (Technically Enhanced Naturally Occurring Radioactive Material) soil was investigated by the IAEA. Fast results were obtained for characterization and certification of a new TENORM Certified Reference Material (CRM), identified as IAEA-448 (soil from oil field). The combined standard uncertainty of the gamma-ray spectrometry results is of the order of 2-3% for massic activity measurement values ranging from 16500 Bq kg(-1) to 21500 Bq kg(-1). Methodologies used for the production and certification of the IAEA-448 CRM are presented. Analytical results were confirmed by alpha spectrometry. The "t" test showed agreement between alpha and gamma results at 95% confidence level. © 2013 Published by Elsevier Ltd.

  15. Spectral distortion of dual-comb spectrometry due to repetition rate fluctuation

    NASA Astrophysics Data System (ADS)

    Hong-Lei, Yang; Hao-Yun, Wei; Yan, Li

    2016-04-01

    Dual-comb spectrometry suffers the fluctuations of parameters in combs. We demonstrate that the repetition rate is more important than any other parameter, since the fluctuation of the repetition rate leads to a change of difference in the repetition rate between both combs, consequently causing the conversion factor variation and spectral frequency misalignment. The measured frequency noise power spectral density of the repetition rate exhibits an integrated residual frequency modulation of 1.4 Hz from 1 Hz to 100 kHz in our system. This value corresponds to the absorption peak fluctuation within a root mean square value of 0.19 cm-1 that is verified by both simulation and experimental result. Further, we can also simulate spectrum degradation as the fluctuation varies. After modifying misaligned spectra and averaging, the measured result agrees well with the simulated spectrum based on the GEISA database. Project supported by the State Key Laboratory of Precision Measurement Technology & Instruments of Tsinghua University and the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 61205147).

  16. Contact sponge water absorption test implemented for in situ measures

    NASA Astrophysics Data System (ADS)

    Gaggero, Laura; Scrivano, Simona

    2016-04-01

    The contact sponge method is a non-destructive in-situ methodology used to estimate a water uptake coefficient. The procedure, unlike other in-situ measurement was proven to be directly comparable to the water uptake laboratory measurements, and was registered as UNI 11432:2011. The UNI Normal procedure requires to use a sponge with known density, soaked in water, weighed, placed on the material for 1 minute (UNI 11432, 2011; Pardini & Tiano, 2004), then weighed again. Difficulties arise in operating on test samples or on materials with porosity varied for decay. While carrying on the test, fluctuations in the bearing of the environmental parameters were negligible, but not the pressure applied to the surface, that induced the release of different water amounts towards the material. For this reason we designed a metal piece of the same diameter of the plate carrying the sponge, to be screwed at the tip of a pocket penetrometer. With this instrument the sponge was kept in contact with the surface for 1 minute applying two different loads, at first pushed with 0.3 kg/cm2 in order to press the sponge, but not its holder, against the surface. Then, a load of 1.1 kg/ cm2 was applied, still avoiding deviating the load to the sponge holder. We applied both the current and our implemented method to determine the water absorption by contact sponge on 5 fresh rock types (4 limestones: Fine - and Coarse grained Pietra di Vicenza, Rosso Verona, Breccia Aurora, and the silicoclastic Macigno sandstone). The results show that 1) the current methodology imply manual skill and experience to produce a coherent set of data; the variable involved are in fact not only the imposed pressure but also the compression mechanics. 2) The control on the applied pressure allowed reproducible measurements. Moreover, 3) the use of a thicker sponge enabled to apply the method even on rougher surfaces, as the device holding the sponge is not in contact with the tested object. Finally, 4) the

  17. Infrared study of the absorption edge of {beta}-InN films grown on GaN/MgO structures

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

    Perez-Caro, M.; Rodriguez, A. G.; Vidal, M. A.

    2010-07-15

    Infrared optical studies were carried out in a group of cubic InN samples grown by gas source molecular beam epitaxy on MgO (001) substrates. Room temperature (RT) reflectance and low-temperature (LT) transmittance measurements were performed by using fast Fourier transform infrared spectrometry. Reflectance fittings allowed to establish that {beta}-InN films have large free-carrier concentrations present (>10{sup 19} cm{sup -3}), a result that is corroborated by Hall effect measurements. Each sample explored exhibited a different optical absorption edge. The Varshni parameters that describe adequately the optical absorption edge responses with temperature are obtained for the set of samples studied. The observedmore » temperatures changes, from LT to RT, are the lowest reported for III-V semiconductor binary compounds. The temperature coefficient of the conduction band depends on the strength of the electron-phonon interaction (e-ph-i), as well as on the thermal expansion. It has been predicted that cubic InN has one of the smallest e-ph-i of all III-V compounds, which is corroborated by these results. The variation in values of absorption edges is clearly consistent with the Burstein-Moss and band renormalization effects, produced by high free electron concentrations. It is shown that the conduction band in {beta}-InN, analogous to wurtzite InN, follows a nonparabolic behavior.« less

  18. Infrared study of the absorption edge of β-InN films grown on GaN/MgO structures

    NASA Astrophysics Data System (ADS)

    Pérez-Caro, M.; Rodríguez, A. G.; Vidal, M. A.; Navarro-Contreras, H.

    2010-07-01

    Infrared optical studies were carried out in a group of cubic InN samples grown by gas source molecular beam epitaxy on MgO (001) substrates. Room temperature (RT) reflectance and low-temperature (LT) transmittance measurements were performed by using fast Fourier transform infrared spectrometry. Reflectance fittings allowed to establish that β-InN films have large free-carrier concentrations present (>1019 cm-3), a result that is corroborated by Hall effect measurements. Each sample explored exhibited a different optical absorption edge. The Varshni parameters that describe adequately the optical absorption edge responses with temperature are obtained for the set of samples studied. The observed temperatures changes, from LT to RT, are the lowest reported for III-V semiconductor binary compounds. The temperature coefficient of the conduction band depends on the strength of the electron-phonon interaction (e-ph-i), as well as on the thermal expansion. It has been predicted that cubic InN has one of the smallest e-ph-i of all III-V compounds, which is corroborated by these results. The variation in values of absorption edges is clearly consistent with the Burstein-Moss and band renormalization effects, produced by high free electron concentrations. It is shown that the conduction band in β-InN, analogous to wurtzite InN, follows a nonparabolic behavior.

  19. Gas Phase Absorption Spectroscopy of C+60 and C+70 in a Cryogenic Ion Trap: Comparison with Astronomical Measurements

    NASA Astrophysics Data System (ADS)

    Campbell, E. K.; Holz, M.; Maier, J. P.; Gerlich, D.; Walker, G. A. H.; Bohlender, D.

    2016-05-01

    Recent low-temperature laboratory measurements and astronomical observations have proved that the fullerene cation {{{C}}}60+ is responsible for four diffuse interstellar bands (DIBs). These absorptions correspond to the strongest bands of the lowest electronic transition. The gas phase spectrum below 10 {{K}} is reported here for the full wavelength range encompassed by the electronic transition. The absorption spectrum of {{{C}}}70+, with its origin band at 7959.2 {{\\mathringA }}, has been obtained under similar laboratory conditions. Observations made toward the reddened star {HD} 183143 were used in a specific search for the absorption of these fullerene cations in diffuse clouds. In the case of {{{C}}}60+, one further band in the astronomical spectrum at 9348.5 \\mathringA is identified, increasing the total number of assigned DIBs to five. Numerous other {{{C}}}60+ absorptions in the laboratory spectrum are found to lie below the astronomical detection limit. Special emphasis is placed on the laboratory determination of absolute absorption cross-sections. For {{{C}}}60+ this directly yields a column density, N({{{C}}}60+), of 2× {10}13 {{{cm}}}-2 in diffuse clouds, without the need to rely on theoretical oscillator strengths. The intensity of the {{{C}}}70+ electronic transition in the range 7000-8000 Å is spread over many features of similar strength. Absorption cross-section measurements indicate that even for a similar column density, the individual absorption bands of {{{C}}}70+ will be too weak to be detected in the astronomical spectra, which is confirmed giving an upper limit of 2 {{m\\mathringA }} to the equivalent width. Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut National des Sciences de l’Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii.

  20. NASA multipurpose airborne DIAL system and measurements of ozone and aerosol profiles. [DIfferential Absorption Lidar

    NASA Technical Reports Server (NTRS)

    Browell, E. V.; Carter, A. F.; Shipley, S. T.; Siviter, J. H., Jr.; Hall, W. M.; Allen, R. J.; Butler, C. F.; Mayo, M. N.

    1983-01-01

    The hardware, operational characteristics, data processing system, and applications of the NASA airborne differential absorption lidar (DIAL) system are described. DIAL functions by assessing the average gas concentration over a specified range interval by analyzing the difference in lidar backscatter signals for laser wavelengths tuned on and off of the molecular absorption line of a gas under investigation. The system comprises two frequency-doubled Nd:YAG lasers pumping two high conversion efficiency tunable dye lasers emitting pulses separated by 100 microsec or less. The return signals are digitized and stored on magnetic tape. The signal collector consists of photomultiplier tubes implanted in a cassegrain telescope. Flight tests of the system involved on-measurements at 285.95 nm and off-measurements at 299.40 nm, which yielded a differential cross section of 1.74 x 10 to the -16th sq cm. In situ measurements with another plane at a nominal altitude of 3.2 km for comparison purposes showed accuracy to within 10% in and above the boundary layer. The system is considered as a test apparatus for more developed versions to be flown on the Shuttle