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Challenges of Conducting Analytical Chemistry in Environmental Matrices

This presentation discusses the challenges faced when conducting analytical chemistry in complex environmental matrices, using specific examples such as PAHs and PBDEs. It also highlights the importance of adaptive management and strong quality assurance and quality control measures.

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Challenges of Conducting Analytical Chemistry in Environmental Matrices

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  1. Challenges of Conducting Analytical Chemistry in Environmental Matrices May 8th 2006 Meg Sedlak and Don Yee San Francisco Estuary Institute Oakland, California

  2. Outline • Overview of the Regional Monitoring Program for Water Quality (RMP) • Challenges of environmental samples • Ubiquitous contaminants, trace concentrations, complex matrices • Specific examples – PAH and PBDEs • Summary

  3. Regional Monitoring Program Founded in 1993 Monitoring trends and distribution of pollutants Estimating loads Measuring exposure and effects

  4. RMP Structure • Funded by NPDES dischargers • Collaborative - Quarterly meetings with dischargers, regulators, & staff • Core element – Status and Trends • Pilot and special studies

  5. Suisun Suisun San Pablo San Pablo Rivers Rivers Bay Bay l l W W =4 =4 W W =4 =4 S S =8 =8 l l l l S S =8 =8 l l l l l l Water: Water: 31 total 31 total Sediment: Sediment: 47 total 47 total W W =4 =4 Central Central S S =8 =8 l Bay Bay l l l l l South South W W =10 =9 Bay Bay S S =8 =8 Suisun Suisun San Pablo San Pablo l l Lower South Lower South l Bay Bay Rivers Rivers Bay Bay W W =5 =6 l l l W =4 l l W =4 S S =8 =8 S =8 l l l l S =8 l l l l l l l Water: 31 total Sediment: 47 total W =4 Central Central Historical fixed station Historical fixed station Historical fixed station = = = l l l S =8 Bay Bay l l l l l l South South W =10 Bay Bay S =8 l l l Lower South Lower South Bay Bay W =6 l l l S =8 Status & Trends Annual Monitoring • Summer • Water, sediment, bivalves, & sportfish • Analytes: • Trace elements (Ag, As, Cd, Cu, Fe, Hg, MeHg, Mn, Ni, Pb, Se, Zn) • Organics (PCBs, PBDEs, Pesticides, PAHs) • Toxicity (sediment & water) • 5 different laboratories

  6. Protecting analyst from sample Regulatory standards vs. Environmental concentrations Protecting sample from the analyst

  7. Sampling & Analysis Chain Supplies & Equipment Field Environment Laboratory Environment Reagents Glassware Cleaning Field Crew “Clean” Containers Collect sample Lab blank Proof Field blank Extract Chemical Analysis Result

  8. Sampling & Analysis Chain Supplies & Equipment Field Environment Laboratory Environment “External” Sources of Contamination Reagents Glassware Cleaning Field Crew “Clean” Containers Collect sample Lab blank Proof Field blank Extract “Internal” Sources of Contamination Chemical Analysis Result

  9. Water Organics- Collection • AXYS system • 1 m below surface • 100 liters • Prefilter, glass filter (1 um pore size) and XAD resin • Extract split 5 ways

  10. Water - Organics • Glass Filters and XAD resin • Soxhlet extracted • 12 hrs, closed loop distillation • Silica gel cleanup • Analysis by GC/MS for PAHs

  11. PAH Blanks 2002 vs. 2003

  12. Water Organics- What changed? • Cleaning • 2003 switched to acid-cleaning of glassware • Change in solvent • stabilizer in toluene (proprietary) • PAH Formation • Mechanism unknown • Activation sites/heat? ? =Si-OH

  13. Alternatives Considered • Other solvents • Acetonitrile/Dichloromethane- recovery problems w/ other analytes (pesticides) • Splitting samples • XAD possible • Filters? No clean-sawing SOP developed

  14. Alternatives Considered (cont’d) • Whole water samples – Pros and Cons • Cons • 5-fold increase in detection limits • Would lose some PAHs (e.g., acenaphthene) • A lot of water samples needed…. • 4 liters per analyte • 31 sites => 620 L => 620 kgs …meaning a whole lot of weight.

  15. Alternatives – Whole Water • Cons: • Liquid-liquid extraction • Time-consuming to extract 4 liter samples • Pros: • Weight training

  16. Alternative Chosen • Ambient Temperature eXtraction (ATX) • Developed by AXYS Analytical • Filters sonicated in acetonitrile and hexane • Good recovery for all analytes

  17. 2003 vs. 2005 PAH Blanks

  18. 2005 Total PAH Concentrations in Water

  19. PBDEsEmerging Contaminant • Wide-spread use • Increase scrutiny • Health effects • Phase out in EU & CA • Deca highest use Source: Stapleton et al., 2005. ES&T 39(4); Wilford et al., 2005 ES&T 39(18); and BSAF.

  20. PBDEsAn Emerging Challenge • Blank contamination in lab environment? • Present in plastics, soft furnishing, electronic equipment

  21. Source: Stapleton et. al, ES&T 39 (4) PBDEs: A spec of dust is important no matter how small ….

  22. Similar challenges with other Emerging Contaminants • Ubiquitous, trace levels, complex matrices • Perfluorinated Compounds • Teflon liners, tubing, septa, textiles • Phthalates • Gloves and septa

  23. Summary • Large-scale environmental monitoring programs require adaptive management • Off-the-shelf methods may not work • Modification of methods • Working with laboratories to solve the problem • Many sources of contamination • Internal contamination (function of the method) • External contamination (introduced as a result of lab environment, supplies, equipment, staff, etc.) • Need strong QA/QC • New analytes = new sources and challenges

  24. Acknowledgements Brian Fowler and Dale Hoover (www.AXYStechnologies.com) Francois Rodigari and Saskia van Bergen (www.EBMUD.com)

  25. Questions? All of RMP data and reports are available on-line at www.sfei.org

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