1. Sampling for semivolatile organic contaminants in environmental compartments
Lisa Rodenburg

2. The Universe of Non-polar Chemicals
PBTs
VOCs = Volatile organic chemicals
SOCs = semivolatile organic chemicals
POPs = Persistent Organic Pollutants
PBTs = Persistent, Bioaccumulative, & Toxic
POPs
VOCs
SOCs

3. Many classes of contaminants can be sampled and measured together:
PCBs = polychlorinated biphenyls = myriad uses, banned since 1970’s = PBTs
PAHs = polycyclic aromatic hydrocarbons = combustion by-products = less P, very BT
PBDEs = polybrominated diphenyl ethers = current use flame retardants = not very P, very B, not sure how T
OCPs = organochlorine pesticides (DDT, etc) = some in current use (α- and γ-HCH, α- and β-endosulfan ), some banned (DDT) = most are PBTs

4. PCBs PCBs consist of 209 congeners, which may have 1 to 10 chlorines.
A group of congeners having the same number of chlorines is a “homolog group”
PCBs were previously sold as “Aroclors” and used as fluids in electrical equipment, particularly transformers and capacitors.
PCBs are classified as probable human carcinogens and have been shown to cause a range of serious non-cancer health effects in animals.
The manufacture, processing, and distribution in commerce of PCBs were banned in 1976 due to concerns over their toxicity and persistence in the environment.
About 1.3 million metric tons of PCBs were produced world-wide.

5. PAHs PAHs are Polycyclic Aromatic Hydrocarbons
They contain 2 or more fused aromatic rings
Products of combustion of any type as well as evaporative emissions from fuels.
A small amount of PAHs are produced naturally (volcanoes, forest fires, etc.)
Humans are exposed to PAHs by breathing contaminated air (including tobacco smoke) and eating grilled foods.
The Department of Health and Human Services (DHHS) has determined that some PAHs may reasonably be expected to be carcinogens.

6. PBDEs OCPs Can have 1-10 bromines, numbered in same was as PCBs
2,2’,4,4’,5-pentabromodiphenyl ether = BDE 99
OCPs
Many different structures and numbers of chlorines
heptachlor
DDT

7. Outline Sampling Cleanup Detection Cautionary Tales Air Water Other
The easy way
The hard way
Detection
GC/ECD
GC/MS
Cautionary Tales
Sampling
Extraction
QA/QC
Cleanup
Detection

8. What are semivolatile contaminants?
On the basis of vapor pressure, we can divide the nonpolar or slightly polar compounds into VOCs and SOCs.
VOCs = vapor pressure > 10-3 atm not on atmospheric particles
SOCs = vapor pressure < 10-6 atm significant fraction on atmospheric particles
Some things fall through the cracks, like naphthalene.

9. VOCs (TO-15) SUMA Canister sampling
Fluorinated, chlorinated, brominated C1, C2, C3 compounds
Mono- and di- chlorobenzenes
Methyl and ethyl benzenes
1,3-Butadiene
Acetone
Acetonitrile
Acetylene
Acrylonitrile
Benzene  
Ethyl Acrylate
Ethyl Tert Butyl Ether
Ethylbenzene
Hexachloro-1,3-Butadiene
Methyl Ethyl Ketone
Methyl Isobutyl Ketone
Methyl Methacrylate
Methyl Tert-Butyl Ether
n-Octane
Propylene
Styrene
Tert-Amyl Methyl Ether
SUMA Canister sampling

10. SOCs PCBs PAHs Organochlorine pesticides PBDEs Others?
Sampled using a high-volume air sampler

11. The Hi-Vol Filter Canister (containing PUF or XAD-2 sorbent)
Vacuum pump
Timer
Measure pressure drop before and after every sample. Calibration curve converts pressure drop to flow rate. Timer gives time, hence volume of air sampled.

12. Pitfalls
Breakthrough of more volatile contaminants (minimize flow rate)
Gas/particle partitioning (minimize flow rate)
Detection limits (maximize flow rate)
Motor instability (pre- and post-calibration)
Contamination from motor, O-rings, etc. (keep everything clean, vent motor)
Measure breakthrough by occasionally cutting a PUF in half and analyzing the top and bottom separately.

13. Sorbent choice
PUF allows greater breakthrough of polar and volatile compounds.
XAD-2 has a huge PAH background, especially low MW PAHs.
PUF can be very clean.
Run lots of blanks!

14. Breakthrough of PCBs on PUF
PCBs can have 1 – 10 chlorines. PCBs are numbered such that higher numbers have more chlorines.
Heavier PCBs, less breakthrough.
Breakthrough significant for PCBs with 3 or less chlorines
Blank contamination

15. Water Sampling Whole water or grab samples Dissolved vs. Particulate
Detection limits require very large samples
Blank contamination a big problem
Volatilization
Dissolved vs. Particulate
Filter for particles, sorbent for dissolved
Choice of sorbent is tough
XAD-2 PAH contamination
Tenax, C18 cleanup problems
Choice of platforms:
Infiltrex – expensive, unreliable
TOPS (Trace Organics Platform Sampler) – a better way?
Pepsi cans – low tech

16. Colloids
Typically a 0.7 mm filter is used, which allows small particles to pass through to be quantified with the apparent dissolved phase.
This leads to the “solids concentration effect”. The apparent distribution between dissolved and particle phases changes as the total amount of solids increases.

17. Other sampling
When sampling for sediment, biota, etc, homogenization and collection of a representative sample are paramount.
Volatilization still a problem – refrigerate or freeze immediately

18. Extraction Techniques: Solvents: Soxhlet Extraction
Accelerated Solvent Extraction (ASE) (high T and pressure minimize amount of solvent needed)
Solvents:
Dichloromethane (toxicity?)
Pet Ether
Hexane (leave behind lipids or more polar compounds)

19. Rotovap
Blowdown

20. Cleanup
Use column chromatography to remove interfering compounds from your sample
Type of analytical method determines the rigor of the cleanup
Adsorbent: Sample Matrix:
Alumina Cleaner Air
Silica Sediment
Florisil Dirtier Sludge
Size Exclusion Chromatography Biota (to remove lipids)
Surrogate recovery

21. Our Alumina Cleanup Bake alumina at 550ºC overnight
Deactivate with 3% wt water
Precondition column
F1 = 13 mL Hexane = PCBs
F2 = 15 mL 2:1 DCM/hexane = PAHs
OCPs, PBDEs split between F1/F2

22. Detection
Detection method is determined by concentration of compound in environmental matrixes.
PCBs = Electron Capture Detection or High-Resolution GCMS
PAHs = GCMS EI
PBDEs = GCMS NCI
Cl Pesticides = GCMS NCI
PCDD/Fs = High-Resolution GCMS

23. GC/ECD
Invented by Lovelock around the late 1950s and early 1960s.
Uses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between electrodes.
When organic molecules that contain electronegative functional groups, such as halogens, phosphorous, and nitro groups pass by the detector, they capture some of the electrons and reduce the current measured between the electrodes.
The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds.
Cost ~ $30,000

24. GC/MS Solute molecules are ionized in the ion source
Resulting fragments are separated on the basis of their mass/charge ratio then detected by an analyzer unit
Ionization by electrons (EI) or gas molecules (CI, Negative or Positive).
NCI similar to ECD (little fragmentation, best for halogenated compounds)
Scan mode give entire mass spectrum = good for identification of unknowns
SIM (selective ion monitoring) mode = much more sensitive
Cost ~ $100,000

25. QA/QC Sample contamination Reproducibility Tracking of mass
Representativeness of samples?

26. Avoiding Contamination
Cleanliness
Bake glassware at 450°C overnight
New aluminum foil
High grade solvents
New building!
Cleaning sampling equipment sometimes difficult
Blanks, blanks, blanks

27. Reproducibility Side-by-side samples Duplicates Matrix spikes
Surrogates

28. Mass Tracking Surrogates Internal standards
Added to track recovery through the various sample processing steps
Must have same or similar physical-chemical properties as analytes
Deuterated or 13C labeled
Non-native congeners (PCBs 14, 23, 65, 166)
Internal standards
Added to allow quantification of mass even though volume is not known
Non-native congeners (PCBs 30, 204; BDE 75)

29. Representativeness of samples?
Homogenize sediments (Bass-o-matic)
Take lots of samples
12th day sampling

30. Special considerations for PBDEs
Flame retardants – designed to break down at high temperatures!
BDE 209 has 10 bromines
extremely labile
MW = 960 g/mol!
Use cold on-column injection
Very short GC column
Avoid light

31. The Pitfalls of Measuring PCBs by ECD
Some PCBs co-elute, and there ain’t nothin’ you can do about it.
Example:
PCB s
This is a GOOD chromatogram!

32. EPA Method 1668A Uses High-resolution GC/MS (about $1 million)
13C labeled compounds:
3 field stds
28 surrogates
3 cleanup stds
5 recovery stds
= 39 stds

33. Trade-Offs
Would you rather have 28 surrogates with 60% recovery, or three surrogates with 95% recovery?
209 congener method can reveal surprises
Contract labs are far from infallible
Contract labs only love your money, not your samples

34. PCB 11 3,3’-dichlorobiphenyl is not found in Aroclors
NYSDEC “found” it accidentally in effluent from PVSC
It is produced inadvertently during pigment manufacture (see Litten et al., 2002)
Most data sets do not look for it.

35. Co-elution a problem even for method 1668A
1668A can differentiate between (for example) PCBs 110 and 77, even though they co-elute, because 110 has 5 chlorines and 77 has 4.
BUT PCBs within a homolog group that co-elute are still quantified together
Contract labs report all co-eluting congeners under the congener with the lowest IUPAC number. 
Example: what is reported as PCB 93 is really (and is primarily PCB 95).

36. Cost Price per sample ~$1,000
METHOD 1668 CALIBRATION SOLUTIONS from Cambridge Isotope Laboratories.
METHOD 1668 CALIBRATION SOLUTIONS SET5X0.2ML $2,400.00
METHOD 1668 DAILY CALIBRATION CHECK STANDARD 0.2 ML $495.00
METHOD 1668A CALIBRATION SOLUTION CS ML $625.00
METHOD 1668A CALIBRATION SOLUTION CS1 0.2 ML $625.00
METHOD 1668A CALIBRATION SOLUTION CS2 0.2 ML $625.00
METHOD 1668A CALIBRATION SOLUTION CS3 0.2 ML $575.00
METHOD 1668A CALIBRATION SOLUTION CS4 0.2 ML $625.00
METHOD 1668A CALIBRATION SOLUTION CS5 0.2 ML $625.00
METHOD 1668A CALIBRATION SOLUTIONS CS1-CS5 SET5X0.2ML $2,450.00
METHOD 1668A CLEAN-UP STANDARD SOLUTION 1.2 ML $575.00
METHOD 1668A INJECTION INTERNAL STANDARD SOLUTION 1.2 ML $1, METHOD 1668A NATIVE TOXICS/LOC SOLUTION 1.2 ML $795.00
METHOD 1668A TOXICS/LOC/WINDOW DEFINING SOLUTION 1.2 ML $2,450.00

37. The pitfalls of measuring OCPs by ECD

38. Comparison of ECD and NCI data
4,4’-DDE
Jersey City: Gas- phase
N = 28
P <
2,4’-DDT
Because OCPs are abundant enough to be detected by a regular GC/MS instrument, the mass spec method is cost-effective.
N = 28
P = 0.03

39. Conclusions Dirty matrices Complex mixtures Cost/benefit analyses
Cleanliness
Blanks, blanks, blanks
Trust but verify