Transcript Introduction to Dioxins

Introduction to PCB Congeners
Presented by Jamie Fox
1 month old doxin
chihuahua mix
puppy , eats hard
food and isn’t potty
trained no worms or
fleas rehomming fee
of 75$ call or text
needs home ASAP
Purpose
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•
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•
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To provide general information on PCB’s.
To describe the analytical methods.
To describe uncommon terms.
Example Reports
To answer your questions.
WHAT ARE PCB’S?
What are PCB’s?
• Aroclors are a mixture of PCB’s numbered by type and
percent chlorine content (i.e. 1242 is 42% chlorine)
• PCB’s are a group of 209 polychlorinated biphenyl
congeners. Commonly referred to by a numbering
system.
• 12 PCB’s (WHO list) are distinguished as a sub-group.
These are considered to be the most toxic. They are
the ones whose toxicity is defined.
• Totals are reported by homolog group, e.g. Total Mono
PCB’s, Totals Di PCB’s, etc. and Total PCB Congeners.
What are PCBs?
209 Mono-Deca PCB Congeners
3’
2’
2
3
4’
Cln
4
5’
6’
6
Polychlorinated Biphenyl
(10 substitution positions)
5
Cln
What are PCBs?
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PCB-77
PCB-81
PCB-105
PCB-114
PCB-118
PCB-123
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PCB-126
PCB-156
PCB-157
PCB-167
PCB-169
PCB-189
The Twelve Toxic Congeners
PCB EFFECTS
The PCB Problem
• Manufactured in US from 1929 to 70’s for
transformers, capacitors, paints, caulk, etc.
• Ubiquitous and persistent in the environment
• Neuroendocrine disruptor, teratogen, likely
carcinogen
• Contaminated sites everywhere—Great Lakes,
Hudson River, Newtown Creek
METHODS
Aroclor Method
Method 8082 is historically the most common
analytical method for measuring PCB’s.
• GC/ECD
• Uses fingerprinting method
• Common RL is low ppb
• Least expensive
PCB Homolog Method
Method 680 is commonly used in conjunction
with pesticide analysis.
• GC/LRMS SIM
• Measures by homolog group
• Common RL is mid ppt
PCB Congener Method
Method 1668 can be used for Clean Water Act
(CWA) compliance (e.g., NPDES permits, TMDL
studies, CBC).
• Versions A, B*, and C exist. Versions A and C are
very similar and of primary concern.
• Existing studies use version A.
• Version C has tighter QA/QC limits, causing about 520% more failures
• Common RL is low ppq
* Version B was largely ignored by laboratory and regulators due to disagreements over QA/QC requirements, too loose in some
areas, too tight in others.
METHOD 1668 USES
TMDL
• TMDL = Total Maximum Daily Load
• Section 303(d) of CWA
• Used to study impacted waterways
• Calculates allowable pollutant discharge limits
that ensures water quality standards are met
• Example: Delaware River
• Delaware River Basin Commission
• Virginia DEQ
Individual Congeners
• Verify weathering of Aroclors
• Due to “fingerprint” nature of Method 8082,
PCBs may still be present
• Weathering may result in Aroclor ND’s that would
be detected as individual congeners
• Congener specific analysis has been used for
source identification based on industrial
process
Bioaccumulation
• Tissue analysis often requires low detection
limits
• Human health concerns drive PCB regulatory
limits lower than traditional analytical method
RLs
ISOTOPE DILUTION
Isotope Dilution
What do we do with the 13C labeled congeners?
(PCBs and Dioxins)
Act as surrogates and internal standards for the
native congeners at each step in the
preparation and analysis:
• Extraction Standards (ES) just before the extraction.
• Cleanup Standards (CS) just before the fractionation.
• Injection Standards (JS) just before the injection.
Isotope Dilution
Extraction Standards (ES)
When?
Extraction Standards are introduced inside the sample
matrix before the extraction step.
Why?
• Used to measure the overall extraction and fractionation
efficiency
• Used in the qualitative and quantitative characterizations
of native congeners
Isotope Dilution
Cleanup Standards (CS)
When?
Cleanup Standards are introduced to the sample after
extraction but prior to the cleanup step (when
applicable.)
Why?
• Used to measure the efficiency associated with the
fractionation step alone.
Isotope Dilution
Injection Standards (JS)
When?
• Injection Standards are introduced to the sample after
cleanup but prior to injection.
Why?
• They act as internal standards to determine the
recoveries of the Extraction and Cleanup Standards.
• Provide a measurement of injection efficiency useful to
the analyst.
HIGH RESOLUTION MASS
SPECTROMETRY
High Resolution Mass Spectrometry
How high is high?
Well, it’s 10000 Resolving Power!
The ability to zoom in on a mass spectrum and tell the
differences between masses that are very close in
weight.
High Resolution Mass Spectrometry
100ppm
5% line
UNCOMMON TERMS
Sample specific Estimated
Detection Limit (EDL)
• Not the same as a Method Detection Limit (MDL)
• The concentration of a given analyte required to
produce a signal with a peak height of at least 2.5
times the background signal level.
• Used for blanks, not for samples as the method is
written
Toxic Equivalency Quotient (TEQ)
• Simplest means of reporting a sample’s toxicity, one
number!
• TEQ is a sum based on the concentration of the toxic
PCB congeners and their relative toxicity to 2,3,7,8TCDD.
• Important client decisions include:
• the choice of Toxic Equivalency Factors (TEFs)
• treatment of non-detects
• the use of EMPCs or not
Example PCB TEQ
TEF
Result
PCB-77
153
WHO2005
Adjusted
TEF
Result
x
0.0001
=
0.0153
PCB-81
x
0.0003
=
0
PCB-105
x
0.00003
=
0
PCB-114
36.2
x
0.00003
=
0.00109
PCB-118
205
x
0.00003
=
0.00615
PCB-123
89.0
x
0.00003
=
0.00267
PCB-126
30
x
0.1
=
3.01
PCB-156/157
431
x
0.00003
=
0.0129
x
0.00003
=
0
PCB-167
PCB-169
105
x
0.03
=
3.15
PCB-189
146
x
0.00003
=
0.00438
TEQ =
6.20
REPORT EXAMPLES
Example 1668 Form
Example 1668 Form
Thank you!
Jamie Fox
505-307-3770
[email protected]
www.capefearanalytical.com