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Search Publications by: William E. Wallace (Fed)

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Displaying 1 - 25 of 110

An Improved Sample Preparation Method for Protein and Peptide Identification from Human Hair

November 27, 2023
Author(s)
Zheng Zhang, William E. Wallace, Guanghui Wang, Meghan Burke Harris, Yi Liu, Sergey Sheetlin, Stephen E. Stein
A fast and sensitive Direct Extraction (DE) method developed in our group can efficiently extract proteins in 30 min from a 5 cm-long hair strand. Previously we coupled DE to downstream analysis using gel electrophoresis followed by in-gel digestion, which

Inferring the nominal molecular mass of an analyte from its electron ionization mass spectrum

August 23, 2023
Author(s)
Arun Moorthy, Anthony J. Kearsley, William Mallard, William E. Wallace, Stephen E. Stein
The performance of three algorithms for predicting nominal molecular mass from an analyte's electron ionization mass spectrum is presented. The Peak Interpretation Method (PIM) attempts to quantify the likelihood that a molecular ion peak is contained in

On the challenge of unambiguous identification of fentanyl analogs: exploring measurement diversity using standard reference mass spectral libraries

July 11, 2023
Author(s)
Arun Moorthy, Edward Erisman, Anthony J. Kearsley, Yuxue Liang, Edward Sisco, William E. Wallace
Fentanyl analogs are a class of designer drugs that are particularly challenging to unambiguously identify due to the mass spectral and retention time similarities of unique compounds. In this paper, we use agglomerative hierarchical clustering to explore

Comprehensive Analysis of Tryptic Peptides Arising from Disulfide Linkages in NISTmAb and Their Use for Developing a Mass Spectral Library

June 22, 2021
Author(s)
Qian Dong, Xinjian Yan, Yuxue Liang, Sanford Markey, Sergey L. Sheetlin, Concepcion Remoroza, William E. Wallace, Stephen Stein
This work presents methods for identifying and then creating a mass spectral library for disulfide-linked peptides originating from the NISTmAb. Analysis involved both partially- reduced and non-reduced proteins under neutral and weakly basic conditions

Mass Spectral Library of Acylcarnitines Derived from Human Urine

April 8, 2020
Author(s)
Xinjian Yan, Sanford Markey, Ramesh Marupaka, Qian Dong, Brian T. Cooper, Yuri Mirokhin, William E. Wallace, Stephen Stein
We describe the creation of a mass spectral library of acylcarnitines and conjugated acylcarnitines from the LC–MS/MS analysis of six NIST urine reference materials. To recognize acylcarnitines, we conducted in-depth analyses of fragmentation patterns of

Sensitive Method for the Confident Identification of Genetically Variant Peptides in Human Hair

October 31, 2019
Author(s)
Zheng Zhang, Meghan Burke, William E. Wallace, Yuxue Liang, Sergey L. Sheetlin, Yuri Mirokhin, Dmitrii Tchekhovskoi, Stephen Stein
Recent reports have demonstrated that genetically variant peptides (GVPs) derived from human hair shaft proteins can be used to differentiate individuals of different biogeographic origin (Parker, G.J.; et al. PLos One. 2016, e0160653). We report a direct

Standard Reference Data Workshop Report

June 12, 2018
Author(s)
Debra L. Kaiser, Neil Alderoty, Richard R. Cavanagh, Barbara Guttman, Robert J. Hanisch, Adam G. Morey, Jeanita Pritchett, Yuri Ralchenko, Stacy S. Schuur, William E. Wallace
On October 17, 2017, the ODI sponsored a day-long Standard Reference Data Workshop. More than 120 NIST staff members and associates from four NIST laboratories and three offices registered for this workshop. The workshop format consisted of presentations

Combining fragment ion and neutral loss matching during mass spectral library searching: A new general-purpose algorithm applicable to illicit drug identification

November 20, 2017
Author(s)
Arun S. Moorthy, William E. Wallace, Anthony J. Kearsley, Dmitrii V. Tchekhovskoi, Stephen E. Stein
A mass spectral library search algorithm that identifies compounds that differ from library compounds by a single ‘inert’ structural component is described. This algorithm, the Hybrid Similarity Search, generates a similarity score based on matching both

Mass Spectral Library Quality Assurance by Inter-Library Comparison

April 2, 2017
Author(s)
William E. Wallace, Weihua Ji, Dmitrii V. Tchekhovskoi, Karen W. Phinney, Stephen E. Stein
A method to discover and correct errors in mass spectral libraries is described. Comparing across a set of highly curated reference libraries compounds that have the same chemical structure quickly identifies entries that are outliers. In cases where three

Pairwise Alignment of Chromatograms using a Fisher-Rao Metric

September 2, 2014
Author(s)
William E. Wallace, Anuj Srivastava, Kelly H. Telu, Yamil Simon
A new approach to aligning chromatograms is introduced and applied to examples of metabolite identification by liquid chromatography mass spectrometry (LC MS). A square root representation of the chromatogram’s derivative coupled with a Fisher Rao

Stochastic Regression Modeling of Chemical Spectra

August 14, 2014
Author(s)
Anthony J. Kearsley, William E. Wallace, Yutheeka Gadhyan
A stochastic regression method has been developed that decomposes chemical spectra into separate contributions from signal and from noise. The numerical results of regressing in this way on sample spectra are presented. The results suggest that this

Metabolite Profiling of a NIST Standard Reference Material for Human Plasma (SRM 1950) – GC/MS, LC/MS, NMR and Clinical Laboratory Analyses, Libraries and Web-based resources

October 22, 2013
Author(s)
Yamil Simon, Mark S. Lowenthal, Lisa E. Kilpatrick, Maureen L. Sampson, Kelly H. Telu, Paul A. Rudnick, William G. Mallard, Daniel W. Bearden, Tracey B. Schock, Dmitrii V. Tchekhovskoi, Niksa Blonder, Xinjian Yan, Yuxue Liang, Yufang Zheng, William E. Wallace, Pedatsur Neta, Karen W. Phinney, Alan T. Remaley, Stephen E. Stein
Recent progress in metabolomics and the development of increasingly sensitive analytical techniques have renewed interest in global profiling, i.e., semi-quantitative monitoring of all chemical constituents of biological fluids. In this work, we have

Automated Data Processing and Quantification in Polymer Mass Spectrometry

December 1, 2011
Author(s)
Till Gruendling, Christopher Barner-Kowollik, William E. Wallace, Charles M. Guttman, Anthony J. Kearsley
An overview is given of some new techniques in quantitative composition and molecular mass distribution measurement of synthetic polymers by mass spectrometry. New concepts in data analysis, including peak picking and integration, are also described.

CONTINUOUS FLOW ENZYME-CATALYZED POLYMERIZATION IN A MICROREACTOR

March 25, 2011
Author(s)
Santanu S. Kundu, Atul S. Bhangale, William E. Wallace, Kathleen M. Flynn, Charles M. Guttman, Richard Gross, Kathryn L. Beers
Enzymes immobilized on solid supports are increasingly used for chemical transformation because the process is greener and sustainable. Here we use microreactors to study enzyme catalyzed ring opening polymerization of -caprolactone to polycaprolactone. A

Molecular Mass Distribution Measurement by Mass Spectrometry

May 19, 2010
Author(s)
William E. Wallace, Charles M. Guttman
This NIST Recommended Practice Guide presents a method using mass spectrometry to make a quantitative determination of the molecular mass distribution of narrow polydispersity synthetic molecular materials. The main obstacle for converting an oligomer

Reactive MALDI Mass Spectrometry of Saturated Hydrocarbons: A Theoretical Study

May 1, 2010
Author(s)
William E. Wallace, Lewandowski Hans, Meier J. Robert
Recently it has been shown that the cobaltocenium cation, prepared by the laser ablation of a CoCp(CO)2/fullerene matrix, may react with alkanes and polyethylenes in the gas phase via a dehydrogenation reaction to produce [Co(Cp)2(alkadiene)]+ ions without

IMMOBILIZED ENZYME CATALYZED POLYMERIZATION REACTIONS IN MICROREACTORS

January 1, 2010
Author(s)
Santanu S. Kundu, Atul Bhangale, William E. Wallace, Kathleen M. Flynn, Richard Gross, Kathryn L. Beers
Application of microreactor technologies enable improved safety, selectivity and yield in a range of chemical reactions in addition to new measurement methods that are often faster, cheaper and more accurate than traditional methods. In this study we have