Sampling for semivolatile organic contaminants in environmental compartments Lisa Rodenburg

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

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

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.

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.

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

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

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.

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

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

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.

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.

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!

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

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

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.

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

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)

Rotovap Blowdown

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

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

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

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

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

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

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

Reproducibility Side-by-side samples Duplicates Matrix spikes Surrogates

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)

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

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

The Pitfalls of Measuring PCBs by ECD Some PCBs co-elute, and there ain’t nothin’ you can do about it. Example: PCB s 110+77 This is a GOOD chromatogram!

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

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

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.

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 93+95+98+100+102 (and is primarily PCB 95).

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 CS0.2 0.2 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 $1,650.00 METHOD 1668A NATIVE TOXICS/LOC SOLUTION 1.2 ML $795.00 METHOD 1668A TOXICS/LOC/WINDOW DEFINING SOLUTION 1.2 ML $2,450.00

The pitfalls of measuring OCPs by ECD

Comparison of ECD and NCI data 4,4’-DDE Jersey City: Gas- phase N = 28 P < 0.0001 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

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