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Comprehensive Detection of Contaminants by Non‐Targeted Mass
Spectrometry
Nathan Dodder
Palos Verdes PBDEs ‐ Sediment Core
2007199319761951
PBDEs identified as a contaminant (1990s)
Restrictions/regulations started (~2004)
• For example, the flame retardant PBDE was missed for decades
• Other recent environmental “surprises” include perfluorinatedcompounds, NDMA, and 1,4 dioxane
• What other new chemicals exist?
Estimated Year1969
Problem 1: Contaminants have been missed because monitoring was too focused.
Problem 2: What compounds are responsible for positive toxicity tests?
• Toxicity Identification Evaluation (TIE)
• E.g., 100s of structurally diverse chemicals are known to interact with the estrogen receptor cell assay
• Likely a mixture of compounds
• Known or unknown compounds
o,p’‐DDT
bisphenol A
C9H19
4‐nonylphenol
Contaminant AnalysisTargeted Analysis: Optimized for quantification of specific analytes
Non‐Targeted Analysis: Optimized for identification of multiple classesof analytes
Targeted Mass Spectrometry
Sample Method Detection
Non‐Targeted Mass Spectrometry
Method DetectionSample
Non‐Targeted Analysis
Analogous to fingerprint ID
Sample
Library
Non‐Targeted Chemical Analysis
• The instrument collects mass spectra of “every” compound in the sample
• Contaminants are identified by• Matching mass spectra using a library
• Manual interpretation SampleMass Spectrum
Library
Non‐Targeted Chemical Analysis
• The instrument collects mass spectra of “every” compound in the sample
• Contaminants are identified by• Matching mass spectra using a library
• Manual interpretation SampleMass Spectrum
Library
ManualInterpretation
Road Map
Periodic Screening1. WWTP Outfalls2. Stormwater3. Bioaccumulation
TIE1. In vitro2. In vivo3. In situ
Contaminants in sample
Hydrophobic Hydrophilic
GC‐based MS
LC‐based MS
SpectralLibrary
SpectralLibrary
Identification relies on databases of mass spectra, which are continuously augmented.
Problem 1: Occurrence Problem 2: Toxicity
Road Map
Periodic Screening1. WWTP Outfalls2. Stormwater3. Bioaccumulation
TIE1. In vitro2. In vivo3. In situ
Contaminants in sample
Hydrophobic Hydrophilic
GC‐based MS
LC‐based MS
SpectralLibrary
SpectralLibrary
Identification relies on databases of mass spectra, which are continuously augmented.
Problem 1: Occurrence Problem 2: Toxicity
Observed Contaminants in Bottlenose Dolphins (GC×GC‐TOF)
• 70% not typically monitored
• 61% not in standard NIST library
• Most abundant classes:1. DDT‐related2. PCB3. Chlordane‐related4. PBDE5. Unknowns6. DMBP (natural
product) 0
20
40
60
80
100
120
140
Number of Observed ContaminantsStranded Specimens (n=8), Blubber,
Southern California Bight
TypicallyMonitored
Not TypicallyMonitored
Anthro‐pogenic
NaturalProducts
MixedSources
Unknown
Comparison to Observed Contaminants in Bird Eggs (GC×GC‐TOF)
0
20
40
60
80
100
120
140
Bottlenose Dolphin Blubber (n=8)Southern California Bight
TypicallyMonitored
Not TypicallyMonitored
0
20
40
60
80
100
120
140
Black Skimmer Bird Eggs (n=4)San Diego Bay
TypicallyMonitored
Not TypicallyMonitored
Num
ber o
f observed contam
inants
Anthro‐pogenic
NaturalProducts
MixedSources
Unknown Anthro‐pogenic
NaturalProducts
Unknown
Current Work: Sentinel Species Assessment• Selection of appropriate sentinel species ensures analytical effort is not wasted
• What is the best sentinel species?• High abundance of a broad set of contaminant classes• Best chances of identifying emerging and/or toxic chemicals of concern
• Factors: habitat, diet, metabolism, availability of specimens
• Current project is the non‐targeted analysis of: 1. Long beaked common dolphins2. Short beaked common dolphins3. Risso’s dolphins4. Sea lions5. Harbor seals6. White sharks
Road Map
Periodic Screening1. WWTP Outfalls2. Stormwater3. Bioaccumulation
TIE1. In vitro2. In vivo3. In situ
Contaminants in sample
Hydrophobic Hydrophilic
GC‐based MS
LC‐based MS
SpectralLibrary
SpectralLibrary
Problem 1: Occurrence Problem 2: Toxicity
Develop contaminant early warning system
• Occurrence trends + TIE results indicate new contaminants of concern
• Occurrence monitoring and TIE linked through use of the same libraries
Future Work: LC‐Based Methods for Water‐Soluble Contaminants
• Many known priority CECs are hydrophilic
• Instrumentation is different than for non‐polar bioaccumulative contaminants• GC‐based vs. LC‐based mass spectrometry• Mass spectral libraries are different • Libraries for LC‐based methods are more limited
• Different teams of collaborators are needed• Researchers generally specialize in one of the two approaches
Future Work: Incorporate into TIE
• Biological tests do not identify specific toxicants• Chemical information is required• Potentially both known and unknown toxicants
• Upcoming Project: Link non‐targeted analysis to in vitro assays• Southern California Stormwater Monitoring Collation • Whole‐water samples analyzed by
• In vitro assays based on mode‐of‐action• GCxGC‐TOF nontargeted analysis (non‐polar compounds)• LC‐Q/TOF nontargeted analysis (polar compounds)
Thank You
Further Information:
Shaul NJ, Dodder NG, Aluwihare LI, Mackintosh SA, Maruya KA, Chivers SJ, Danil K, Weller DW, Hoh E. Nontargeted Biomonitoring of Halogenated Organic Compounds in Two Ecotypes of Bottlenose Dolphins (Tursiops truncatus) from the Southern California Bight. Environ. Sci. Technol. 2015, 49(3):1328‐38. doi: 10.1021/es505156q.
Hoh E, Dodder NG, Lehotay SJ, Pangallo KC, Reddy CM, Maruya KA. Nontargetedcomprehensive two‐dimensional gas chromatography/time‐of‐flight mass spectrometry method and software for inventorying persistent and bioaccumulative contaminants in marine environments. Environ. Sci. Technol. 2012, 46(15):8001‐8. doi: 10.1021/es301139q.