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Chemistry

Analytical chemistry

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  • Published Date
Displaying 1201 - 1225 of 2094

Comparison of Orthogonal Mass Spectrometry Platforms for the Determination of Amino Acid Concentrations in Human Plasma Certifying NIST Standard Reference Material 1950

August 16, 2010
Author(s)
Mark S. Lowenthal, Karen W. Phinney, Elizabeth A. McGaw
Absolute concentrations of amino acids in a human plasma pool were determined independently using four quantification methods. Orthogonal separation schemes (LC, GC, or GCxGC) and detection systems (triple quadrupole or time-of-flight mass spectrometers)

Flow Visualization Techniques for the Evaluation of Non-Contact Trace Contraband Detectors

August 1, 2010
Author(s)
Matthew E. Staymates, Wayne Smith, John G. Gillen, Richard T. Lareau, Robert A. Fletcher
Efforts are underway in the Surface and Microanalysis Science Division at the National Institute of Standards and Technology to study trace aerodynamic sampling of explosive particles using walk-through portal-based detection systems. Explosive trace

Spectroscopy with a coherent dual frequency comb interferometer at 3.4 mm

August 1, 2010
Author(s)
Esther Baumann, Fabrizio R. Giorgetta, Ian R. Coddington, William C. Swann, Nathan R. Newbury
A coherent dual fiber-comb spectrometer centered at 1.5 µm wavelengths is transferred to 3.4 µm by difference-frequency generation with a 1064 nm cw laser. It is shown that the residual linewidth between the comb teeth at 3.4 µm is resolution-limited to

Polycyclic Aromatic Hydrocarbons (PAHs) in a Coal Tar Standard Reference Material - SRM 1597a Updated

July 20, 2010
Author(s)
Stephen A. Wise, Dianne L. Poster, Stefan D. Leigh, Catherine A. Rimmer, Stephanie Mossner, Patricia Schubert, Lane C. Sander, Michele M. Schantz
SRM 1597 Complex Mixture of Polycyclic Aromatic Hydrocarbons from Coal Tar, originally issued in 1987, was recently reanalyzed and reissued as SRM 1597a with 34 certified, 46 reference, and 12 information concentrations for polycyclic aromatic hydrocarbons

Polycyclic Aromatic Hydrocarbons (PAHs) in a Coal Tar Standard Reference Material - SRM 1597a Updated

July 20, 2010
Author(s)
Stephen A. Wise, Dianne L. Poster, Stefan D. Leigh, Catherine A. Rimmer, Stephanie Mossner, Patricia Schubert, Lane C. Sander, Michele M. Schantz
SRM 1597 Complex Mixture of Polycyclic Aromatic Hydrocarbons from Coal Tar, originally issued in 1987, was recently reanalyzed and reissued as SRM 1597a with 34 certified and 46 reference concentrations for polycyclic aromatic hydrocarbons (PAHs) and

Thermodynamic, Transport, and Chemical Properties of Reference JP-8

July 14, 2010
Author(s)
Thomas J. Bruno, Marcia L. Huber, Arno R. Laesecke, Eric W. Lemmon, Mark O. McLinden, Stephanie L. Outcalt, Richard A. Perkins, Beverly L. Smith, Jason A. Widegren
This report contains a summary of research conducted to develop a standard or accepted set of thermophysical properties for the aviation kerosene, JP-8. This report is the culmination of a three year effort that included the participation of most of the

Optimizing the Conditions of a Multiple Reaction Monitoring Assay for Membrane Proteins: Quantification of Cytochrome P450 11A1 and Adrenodoxin Reductase in Bovine Adrenal Cortex and Retina

July 1, 2010
Author(s)
Illarion V. Turko, Wei-Li Liao, Gun-Young Heo, Nathan G. Dodder, Irina A. Pikuleva
Although 30% of naturally occurring proteins are predicted to be embedded in biological membranes, membrane proteins are traditionally understudied due to limitations of the available analytical tools. To be applicable to the analysis of membrane proteins

Standard Photoacoustic Spectrometer: Model and Validation using O2 A-Band Spectra

June 30, 2010
Author(s)
Keith A. Gillis, Daniel K. Havey, Joseph T. Hodges
We model and measure the absolute response of an intensity-modulated photoacoustic spectrometer comprising a 10 cm long resonator and having a Q-factor of approximately 30. We present a detailed theoretical analysis of the system and predict its response

Determination of Organic Acids in Vaccinium Berry Standard Reference Materials

June 27, 2010
Author(s)
Melissa M. Phillips, Lane C. Sander, Katherine E. Sharpless, Stephen A. Wise, Catherine A. Rimmer, Ryan Case, James H. Yen
Nine organic acids (citric acid, galacturonic acid, glycolic acid, isocitric acid, malic acid, oxalic acid, quinic acid, shikimic acid, and tartaric acid) and two anions (phosphate and sulfate) were determined in a suite of Vaccinium berry containing

Measurement of residual stress field anisotropy at indentations in silicon

June 23, 2010
Author(s)
Yvonne B. Gerbig, Stephan J. Stranick, Robert F. Cook
The residual stress field around spherical indentations on single crystal silicon (Si) of different crystallographic orientation is mapped by confocal Raman microscopy. All orientations exhibit an anisotropic stress pattern with an orientation specific

High frequency characterization of a Schottky contact to a GaN nanowire bundle

June 16, 2010
Author(s)
Chin J. Chiang, Thomas M. Wallis, Dazhen Gu, Atif A. Imtiaz, Pavel Kabos, Paul T. Blanchard, Kristine A. Bertness, Norman A. Sanford, Kichul Kim, Dejan Filipovic
A GaN nanowire (NW) Schottky contact was characterized up to 10 GHz. Using a calibration procedure and circuit model a capacitance-voltage (CV) curve was obtained, from which a carrier concentration was calculated for the first time. These results

Tunable laser spectroscopy referenced with dual frequency combs

June 15, 2010
Author(s)
Fabrizio R. Giorgetta, Ian R. Coddington, Esther Baumann, William C. Swann, Nathan R. Newbury
Frequency combs provide broadband spectroscopic measurements with high frequency accuracy and precision. However, because the comb power is distributed over a broad spectrum, the sensitivity can be low unless some form of multiplexed detection or cavity

Quality Focus: Certified Reference Materials

June 1, 2010
Author(s)
Katherine E. Sharpless
In June of this year, the final stage of the staggered implementation of current Good Manufacturing Practices (cGMPs) took effect, requiring all domestic and foreign companies that manufacture, package, label, or hold dietary supplements to comply with its
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