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Chemistry

Analytical chemistry

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Displaying 401 - 425 of 2084

PRIMARY STANDARDIZATION OF THE MASSIC ACTIVITY OF A PROTACTINIUM-233 SOLUTION

August 23, 2018
Author(s)
Ryan P. Fitzgerald, Leticia S. Pibida
Protactinium-233 (233Pa) is used as a tracer for radiochemical analysis and is of particular interest as an isotope dilution mass spectrometry (IDMS) spike for 231Pa/235U radio- chronometry. To this end, we present massic activity determinations by two

Nanoscale partitioning of Paclitaxel in Hybrid Lipid-Polymer Membranes

August 6, 2018
Author(s)
Mohit Tuteja, Minjee Kang, Cecilia Leal, Andrea Centrone
Paclitaxel is a powerful drug against restenosis and many forms of cancer. However, its clinical application hinges on the ability to achieve suitable stabilized drug concentrations in an aqueous suspension while hindering drug crystallization. To engineer

A new realization of SI for organic chemical measurement: NIST PS1 Primary Standard for quantitative NMR (Benzoic Acid)

July 30, 2018
Author(s)
Michael A. Nelson, Jason F. Waters, Blaza Toman, Brian E. Lang, Alexander R?ck, Kathrin Breitruck, Markus Obkircher, Anthony Windust, Katrice A. Lippa
Metrological traceability to common references supports the comparability of chemical measurement results produced by different analysts, at various times, and at separate places. Ideally, these references are realizations of base units of the

Determination of polypeptide conformation in water with nanoscale resolution in water

July 24, 2018
Author(s)
Georg Ramer, Francesco Ruggeri, Aviad Levin, Toumas Knowles, Andrea Centrone
The conformational structure and folding of proteins are central to many biological processes. However, misfolding of proteins and peptides can lead to toxic aggregates that are involved in Alzheimer’s and other neurodegenerative disorders. Methods to

Creating a Mass Spectral Reference Library for Oligosaccharides in Milk

July 3, 2018
Author(s)
Concepcion A. Remoroza, Tytus D. Mak, M. L. De Leoz, Yuri A. Mirokhin, Stephen E. Stein
We report the development and availability of a mass spectral reference library for oligosaccharides in human milk. This represents a new variety of spectral library that includes consensus spectra of compounds annotated through various data analysis

Determination of polycyclic aromatic hydrocarbons with molecular mass 302 in standard reference material 1597a by reversed-phase liquid chromatography and stop-flow fluorescence detection

June 21, 2018
Author(s)
Hugh Hayes, Walter Wilson, Lane Sander, Stephen Wise, Andres Campiglia
The identification of isomeric polycyclic aromatic hydrocarbons (PAHs) in complex samples via reversed-phase liquid chromatography (RPLC) with fluorescence detection (FL) is normally based on matching the chromatographic retention times of suspected peaks

An Iterative Qualitative - Quantitative Sequential Analysis Strategy for Electron-Excited X-ray Microanalysis with Energy Dispersive Spectrometry: Finding the Unexpected Needles in the Peak Overlap Haystack

June 20, 2018
Author(s)
Dale E. Newbury, Nicholas Ritchie
When analyzing an unknown by electron-excited energy dispersive X-ray spectrometry with the entire periodic table possibly in play, how does the analyst discover minor and trace constituents when their peaks are overwhelmed by the intensity of an

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
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