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| Mass Spectral and Chromatographic Data |
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| Objective: |
| Provide a comprehensive, fully evaluated mass spectral library for compound identification along with auxiliary reference information and effective methods for accessing the data. |
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| Description: |
| Mass spectrometry, in all its many variants, is an enormously important analytical tool enabling the identification of the chemical compounds present in a sample and in many cases enabling assurance of the absence of certain compounds in that sample. Mass spectrometers are found in a very wide range of analytical applications, for example, environmental quality, flavors and fragrances, drugs, foods, biomedical research, forensics, chemical weapons monitoring, and throughout the chemical and petrochemical industry. Instrumentation for mass spectrometry accounts for global revenues in the billions of dollars each year. Two areas of very rapid growth are applications in homeland security and biomedical research - from the research lab to the clinic. A key step in chemical identification is an automated 'library search' where measured spectra are compared to those in a comprehensive mass spectral library. The procedure not only suggests the identity of the compound of interest but, equally importantly, eliminates others from consideration. The reliability of these identifications depends not only on the comprehensiveness of the reference library, but also on the quality of library spectra and the effectiveness of spectral comparison algorithms. This project addresses each of these elements in a scientifically balanced portfolio of research, data collection, and evaluation. The major output of the project is the NIST/EPA/NIH Mass Spectral Library - the highest quality, most comprehensive collection of reference spectra in the world. It is incorporated as an integral part of the software systems of 10's of thousands of instruments throughout the world - with over 2000 new installations occurring each year. To support the growing application of mass spectrometry in the biomedical area, e.g. in proteomics, metabolomics, etc., the reference collection and supporting search and analysis algorithms are being expanded to include MS/MS spectra. Special purpose analytical methodologies are researched and appear in continual upgrades of openly available software such as AMDIS (Automated Mass Spectral Deconvolution and Identification System). Ancillary data required for enhanced compound identification are added as needed, for example future releases of the library will include a GC (gas chromatography separation method) Retention Index for 10's of thousands of compounds. Current tasks in this project include: “EI MS library for use in GC/MS data systems”, “Enhance Automated MS Deconvolution and Identification System”, and “MS/MS database for use across multiple instrument platforms” |
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| Area(s) of Application: |
- Industrial and Analytical Instruments
- Health and Medical Products and Services
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| Accomplishments: |
- Invention of a New Class of Ultra-fast, Ultra-sensitive Mass Spectrometers: The first Hadamard TOF mass spectrometer incorporating an electron-impact ionizer has been invented, designed, and constructed at NIST. The instrument appears similar to a commercial Reflection TOF mass spectrometer; however, it contains a specialized electron gun, ion optics, and high voltage electronics that are optimized for high frequency modulation. Laboratory tests have demonstrated that this ionizer can switch ion streams on and off with a 5 ns rise-fall time when modulated at 13 MHz. These performance specifications will permit Hadamard operation. Integration of this hardware with the necessary software is in progress.
- Mass Spectroscopy in Health and Environmental Science: A result of the explosive growth in the use of mass spectrometers in all areas of health research and the biosciences the number of proteins mass spectra measured has grown dramatically in the last few years. However, little attention has been paid to the basic reproducibility of peptide mass spectra and to the development of effective means of establishing their accuracy. The first large scale attempt to determine the variability of these peptide spectra is being done at NIST. In this project we are using thousands of openly available spectra along with some specific measurements made at NIST. By examining the variability created by changing the apparatus and measurement conditions in well understood ways, we are beginning to understand the best way to establish a measure of confidence in a peptide spectrum and to define new algorithms to compensate for this variability in identification of the proteins by electrospray LC/MS/MS.
- AMDIS – Automatic Mass spectral Deconvolution and Identification Software: AMDIS was originally developed for detection of chemical weapons in complex mixtures such as might be found in the environment or in chemical process streams. It was designed to work without analyst input as a method of insuring that sensitive business information that could be present in a process stream was not compromised. In the last year the growth in the use of AMDIS by the organic analytical community has been very strong. One of the most exciting developments has been the incorporation of AMDIS into a new set of tools for automatic analysis developed by Agilent Technologies. The tools have been given the general name of Deconvolution Reporting Software (DRS) and incorporate Agilent Technologies run time locking technology, the NIST search software, and AMDIS in a combined tool to allow users to identify pesticides more confidently and at lower concentrations and with more confidence than had been possible with the Agilent system alone.
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| Future Plans: |
- Ultra-fast, Ultra-sensitive Mass Spectrometers: This project will continue along practical avenues. The present Hadamard mass spectrometer will be used to obtain feasibility data for an MS-MS instrument. The design target is an instrument that can measure the kinetics of complex hydrocarbon mixtures. The community also needs data from a well-characterized experiment to verify assumptions about the nature of Hadamard measurements. Since we plan to incorporate error correction algorithms into the NIST HT-TOFMS, we can generate this benchmark reference data. This data may facilitate improvements in other Hadamard application fields including microscopy, NMR, and medical MRI.
- Mass Spectroscopy in Health and Environmental Science: Plans are being developed to build high quality libraries of commonly observed peptides from both directed measurements of selected proteins at NIST and from the vast and growing information available in repositories being developed in the health science community.
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| Other related project work: |
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| External Collaborators: |
The use of AMDIS with the DRS is discussed in three Agilent technical notes:
- P. Wylie, M. Szelewski, and C.K. Meng “Comprehensive Pesticide Screening by GC/MSD using Deconvolution Reporting Software”, Agilent Technologies publication 5989-1157EN. http://www.chem.agilent.com/scripts/LiteraturePDF.asp?iWHID=37589
- M. Szelewski and B. Quimby, “New Tools for Rapid Pesticide Analysis in High Matrix Samples”, Agilent Technologies publication 5989-1716EN. http://www.chem.agilent.com/scripts/LiteraturePDF.asp?iWHID=38704
- C.P. Sandy, “A Blind Study of Pesticide Residues in Spiked and Unspiked Fruit Extracts Using Deconvolution Reporting Software”, Agilent Technologies publication 5989-1654EN. http://www.chem.agilent.com/scripts/LiteraturePDF.asp?iWHID=38636
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| Principal Investigator:
Gary Mallard |
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