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Chemistry

Analytical chemistry

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  • Published Date
Displaying 426 - 450 of 2094

Final Report for CCQM-K6.2: Determination of Total Cholesterol in Human Serum

June 7, 2018
Author(s)
Stephen Wise, Karen W. Phinney, David L. Duewer
Cholesterol is one of the most frequently measured substances in human blood/serum to assist in assessing the health status of individuals. Because of its clinical significance, CCQM-K6 Determination of Cholesterol in Serum was completed in 2000 as one of

DETECTORS FOR LIQUID CHROMATOGRAPHY

June 1, 2018
Author(s)
Thomas J. Bruno, Paris D. Svoronos
The following table provides some comparative data for interpretation of results from the more common detectors applied to high-performance liquid chromatography1-6. In general, the operational parameters provided are for optimized systems, and represent

EDS Microanalysis: Pushing the Limits

June 1, 2018
Author(s)
Nicholas Ritchie, Dale E. Newbury, Michael Mengason, Heather Lowers
It is a great time to be a microanalyst. After a few decades of incremental progress in energy dispersive X-ray spectrometry (EDS), the last decade has seen the accuracy and precision surge forward. Today, the question is not whether EDS is generally

Nanoscale photocurrent mapping in perovskite solar cells

June 1, 2018
Author(s)
Yohan Yoon, Dongheon Ha, Ik Jae Park, Paul M. Haney, Sangwook Lee, Nikolai Zhitenev
In this work, we study spatially-resolved generation of photocurrent of methylammonium lead iodide (CH3NH3PbI3) perovskite solar cells to reveal the microscopic effects of annealing temperature and degradation under light exposure. Correlating a novel

Metrology for stable isotope reference materials: 13C/12C and 18O/16O isotope ratio value assignment of pure carbon dioxide gas samples on the Vienna PeeDee Belmnite-CO2 scale using dual-inlet mass spectrometry

May 25, 2018
Author(s)
Abneesh Srivastava, R M. Verkouteren
Isotope ratio measurements have been conducted on a series of isotopically distinct pure CO2 gas samples using the technique of dual-inlet isotope ratio mass spectrometry (DI-IRMS). The influence of instrumental parameters, data normalization schemes on

Qualitative characterization of three combustion-related standard reference materials for polycyclic aromatic sulfur heterocycles and their alkyl-substituted derivatives via gas chromatography/mass spectrometry

May 7, 2018
Author(s)
Walter Wilson, Hugh Hayes, Andres Campiglia, Stephen Wise
This study represents the most comprehensive qualitative characterization of three combustion- related standard reference materials (SRMs) for polycyclic aromatic sulfur heterocycles (PASHs) and some alkyl-substituted (alkyl-) derivatives to date: SRM

Recent Advances in Ambient Mass Spectrometry of Trace Explosives

May 6, 2018
Author(s)
Thomas Forbes, Edward Sisco
Ambient mass spectrometry has evolved rapidly over the past decade, yielding a plethora of platforms and demonstrating scientific advancements across a range of fields from biological imaging to rapid quality control. These techniques have enabled real

NIST Spectroscopic Measurement Standards

May 1, 2018
Author(s)
Paul C. DeRose, Kenneth D. Cole, Aaron Urbas, Steven J. Choquette, Evelyn Solis, Erica V. Stein, John E. Schiel, Brian Lang, Hua-Jun He
Ultraviolet (UV) absorbance measurements provide a rapid and reliable method to determine protein concentrations. The National Institute of Standards and Technology (NIST) has developed Standard Reference Material (SRM) 2082as a pathlength standard for UV

The role of mass spectrometry in the characterization of biologic protein products

April 25, 2018
Author(s)
Deepali Rathore, John E. Schiel, Anneliese Faustino, Eric Pang, Michael Boyne, Sarah M. Rogstad
Introduction: Mass spectrometry (MS) is widely used in the characterization of biomolecules including peptide and protein therapeutics. These biotechnology products have seen rapid growth over the past few decades and continue to dominate the global

High temperature performance of the HITEMP2010 and HITRAN Online databases: comparison with frequency comb measurements of water vapor absorption from 6800 cm-1 to 7200 cm-1

April 3, 2018
Author(s)
Paul J. Schroeder, D Pfotenhauer, J Yang, William C. Swann, Ian R. Coddington, Nathan R. Newbury, Greg B. Rieker
The HITEMP2010 and HITRAN Online databases are important tools for predicting molecular absorption under various environmental conditions. At room temperature the databases can be quite accurate, owing to their development using room temperature absorption

Perfluorinated Alkyl Acids and Fecundity Assessment in Striped mullet (Mugil cephalus) at Merritt Island National Wildlife Refuge

April 1, 2018
Author(s)
John Bowden, Jacqueline T. Bangma, Jessica L. Reiner, Russell H. Lowers, Theresa M. Cantu, Jacob Scott, Jeffery Korte, Douglas M. Scheidt, Chris McDonough, Jonathan Tucker, Eric Reyier, Douglas H. Adams, Bonnie Ahr, Brenton Back
This study investigated wild caught Striped mullet (Mugil cephalus) at Merritt Island National Wildlife Refuge (MINWR) for levels of 15 perfluoroalkyl acids (PFAAs) in tandem with fecundity measurements (n = 42) and oocyte developmental stages (n = 128)

Performance and failure modes of Si anodes patterned with thin-film Ni catalyst islands for water oxidation

March 6, 2018
Author(s)
Ke Sun, Nicole L. Ritzert, Jimmy John, Haiyan Tan, William G. Hale, Jingjing Jiang, Kimberly M. Papadantonakis, Thomas P. Moffat, Bruce S. Brunschwig, Nathan S. Lewis
Silicon photoanodes patterned with Ni thin film catalyst islands exhibited stable oxygen evolution for over 240 h of continuous operation in 1.0 mol L-1 KOH(aq) under simulated sunlight conditions. Buried-junction np+-Si(111) photoanodes with an 18.0%

Semiempirical Configuration Interaction Calculations for RuCentered Dyes

February 18, 2018
Author(s)
Lisa A. Fredin, Thomas C. Allison
Computational investigation of of the photochemical properties of transition-metal-centered dyes typically involves optimization of the molecular structure followed by calculation of the UV/Visible spectrum. At present, these steps are usually carried out

Examining Heat Treatment for Stabilization of the Lipidome

February 16, 2018
Author(s)
John Bowden, Candice Z. Ulmer, Christina Jones, Tracey Johnston, Jeremy P. Koelmel, Timothy J. Garrett, Richard A. Yost
Aim: To confidently determine lipid-based biomarkers, it is important to minimize variation introduced during preanalytical steps. We evaluated reducing variation associated with lipid measurements in invertebrate sentinel species using a state-of-the-art

Reverse and Random Decoy Methods for False Discovery Rate Estimation in High Mass Accuracy Peptide Spectral Library Searches

February 2, 2018
Author(s)
Zheng Zhang, Meghan C. Burke, Yuri A. Mirokhin, Dmitrii V. Tchekhovskoi, Sanford P. Markey, Wen Yu, Raghothama Chaerkady, Sonja Hess, Stephen E. Stein
Spectral library searching (SLS) is an attractive alternative to sequence database searching (SDS) for peptide identification due to its speed, sensitivity, and ability to include any selected mass spectra. However, SLS does not have a widely tested and
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