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Mass Spectrometry Data Center
NIST Mass Spectral Librariesin Forensic Trace Analysis
Trace Evidence Data Workshop7/19/2016
William E. WallaceNIST Mass Spectrometry Data CenterBiomolecular Measurement DivisionMaterial Measurement Laboratory
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Mass Spectrometry Data Center
• Toxicology/cause of death
• urine, blood
• hair, saliva, sweat
• Profiling
• determination of sample origin
• Explosive/gun shot residues
• Linking residues to people
• Arson investigation
• Determination of accelerants
• Paints/inks/dyes/colorants
• Pharmaceutical adulterants
• Especially in the developing world
•
MS Applied to Forensic Trace Analysis
… a (very) partial list
a NIST MSDC mass spectrometry lab
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Mass Spectrometry Data Center
Why Mass Spectrometry?
Mass spectrometry is developing rapidly in the areas of sensitivity, specificity, and analytical throughput
• Handling of small volumes• Clean up of complex samples
• solid phase extraction
• New ionization methods• DART
• Greater efficiency in ionization• Increased mass resolution• Increased ion throughput
• Improved signal to noise• New signal processing approaches
• Development of new software tools• Sophisticated new algorithms
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Mass Spectrometry Data Center
The NIST Mass Spectrometry Data Center rests on a central tenet—
Libraries are a necessity in identifying compounds from mass spectra
• Why?
• There is no comprehensive theory accurate enough to predict mass spectra for the
purpose of compound identification
• Although theory is useful for interpretation
• Consequently, library creation by systematic, comprehensive measurement has a long
history in mass spectrometry…
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Mass Spectrometry Data Center
… particularly at the National Bureau of Standards
• Brewer & Dibeler, Journal of Research of the National Bureau of Standards, 1945
• “The ratios in which the fragments occur are the same over a wide pressure range for each
molecular species but are never the same for different species”
NIST Archives photodated Sept. 29, 1948
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Mass Spectrometry Data Center
Evolution of the NIST MS Library
NIH/EPA ‘Collection of Collections’(Bethesda)Fales, Heller
‘Classic’ Red Reference Books 9-track Tape
To NIST PC-XT Version
Evaluated Library AMDIS
Exact m/z Peptides
To EPA(Cincinnati)
Budde
Add Chemical Structures
Begin Manual Evaluation
Tandem MS GC Retention
2000’s1990’s1980’s1970’s 2010’s
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Mass Spectrometry Data Center chemdata.nist.gov
• NIST/EPA/NIH Mass Spectral Database• Electron-impact ionization mass spectra typical of GC-MS analysis
• NIST Tandem MS Database• Electrospray ionization mass spectra typical of LC-MS analysis
• DART Forensics Library• For analysis directly from surfaces
• An example of a ‘targeted’ library
NIST Mass Spectral Libraries in Trace Analysis
DART— direct analysis in real time
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Mass Spectrometry Data Center
NIST MSDC Software Tools
• Handling of small volumes• Clean up of complex samples
• solid phase extraction
• New ionization methods• DART
• Greater efficiency in ionization• Increased mass resolution• Increased ion throughput
• Improved signal to noise• New signal processing approaches
• Development of new software tools• Testing new algorithms
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Mass Spectrometry Data Center
NIST GC-MS Library Search
QuerySpectrum
LibrarySpectrumHit
List
ScoreHistogram
SearchList
CompareSpectra
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Mass Spectrometry Data Center
AMDISAutomated Mass Spectral Deconvolution and Identification System
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Mass Spectrometry Data Center
NIST MS Interpreter
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Mass Spectrometry Data Center
What does the NIST MSDC need from the forensics community?
• What are the emerging trends that you are seeing in your labs?
• What compounds do they involve?
• How may NIST obtain certified samples?
• purchase
• synthesis
• isolation from original matrix
• What can the NIST MSDC do to help build the community?
• an interlaboratory round robin?
• training on library searching?
• guidance on uncertainty/false discovery rates?
MSDC staff meeting with customers at our trade show booth
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Mass Spectrometry Data Center
NIST MS Data Center Staff, Spring 2016
Questions?