Mercury Monitoring The FDEP Laboratory Perspective Timothy W. Fitzpatrick (850)

Considerations: Compliance versus Environmental Monitoring  Sample Kit Preparation  Sampling Protocols  Laboratory Design  Analytical Rigor  Data Interpretation

FDEP’s Experience  Constructed Class 1000/100 in mid-1990s;  Adopted Method 1631 w/ some modifications from initial EPA version (semi-automated the method, investigated aqua regia digestion);  Developed fully automated methylmercury analysis in late 1990s using direct ethylation P&T GCAF;  EPA incorporated semi-automated advances in Method 1631E; Automation of Draft Method 1630 under evaluation by EPA Region IV;

FDEP’s Experience  Primary Client Focus: Environmental Monitoring and Research  Detection Limits: THg ~ 100 pg/L (0.10 ng/L) MeHg ~ 20 pg/L (0.02 ng/L)  Initiated Everglades Mercury Round Robins ca. 2000

Introduction to Method 1669 “Clean hands/dirty hands” sampling “Clean hands/dirty hands” sampling Ultra-trace detection levels and methods Ultra-trace detection levels and methods  Tables listing applicable levels in sampling methods “Mindset” and technique “Mindset” and technique  Protection of sample against contamination

Sampling Kits  Double Bagged, Pre-Cleaned Vessels of Glass, Teflon or Surface Fluorinated P-E Prepared in Laboratory  Prices: Glass < Fluor. PE <<< Teflon  Pre-Cleaned Sampling Equipment May Be Needed ( Teflon Tubing, Silicon Pump Tubing, Filtration Devices, etc.)  Laboratories are Sources of Contamination! (Air, DI Water, Reagents, etc.)  Clean Benches or Clean Room Strongly Recommended for Equip. Preparation (Absolute Necessity for Environ. Monitoring)

Sampling by Method 1669 Performance Based Method Performance Based Method Compliance vs. Environmental Monitoring: When is the Full-Blown Method Necessary (or Practical)? Compliance vs. Environmental Monitoring: When is the Full-Blown Method Necessary (or Practical)? Our Experience w/ Hg – Most Contamination Occurs in the Laboratory Our Experience w/ Hg – Most Contamination Occurs in the Laboratory Vessels Need to be Prepared in a ‘Clean’ Laboratory Environment Vessels Need to be Prepared in a ‘Clean’ Laboratory Environment

Sample Collection SOP DEP SOP FS 8200 DEP SOP FS 8200  Adapted from EPA 1669 Adapted from EPA 1669 “Performance-based” concept “Performance-based” concept Verify performance with blanks & other QC Verify performance with blanks & other QC Sampling team practice recommended Sampling team practice recommended

Field Contamination Issues Source of analyte-free water for field blanks and equipment blanks Source of analyte-free water for field blanks and equipment blanks Sampling equipment and sample containers Sampling equipment and sample containers Sampling personnel and clothing Sampling personnel and clothing Ambient sampling environment Ambient sampling environment Sampling techniques Sampling techniques

Sampling Equipment Decontamination Minimum amount of pre-cleaned equipment (only) recommended ; Minimum amount of pre-cleaned equipment (only) recommended ; Controlled environment for cleaning; Controlled environment for cleaning; See FS 8200 cleaning procedures; See FS 8200 cleaning procedures; Specific cleaning procedure for mercury; Specific cleaning procedure for mercury; All pre-cleaned items wrapped for field use; All pre-cleaned items wrapped for field use; Field-based cleaning not recommended; Field-based cleaning not recommended; Dippers not recommended; Collect directly into sample bottles where possible; Dippers not recommended; Collect directly into sample bottles where possible;

On-site Precautions All equipment and supplies in covered storage until use All equipment and supplies in covered storage until use Keep hands and equipment away from contamination sources Keep hands and equipment away from contamination sources Adhere to “clean hands/dirty hands” protocols Adhere to “clean hands/dirty hands” protocols Change gloves when needed Change gloves when needed Collect least contaminated source first Collect least contaminated source first Develop a ‘contamination sensitive’ mindset

Precautions for Sampling Equipment & Protective Clothing Caution advised with pigmented materials, bottle labels, ink Caution advised with pigmented materials, bottle labels, ink See FS 8200 for recommended sampling equipment and materials to avoid See FS 8200 for recommended sampling equipment and materials to avoid Wrap cleaned pump tubing ends Wrap cleaned pump tubing ends Don’t contaminate tubing with pump or extension device Don’t contaminate tubing with pump or extension device

Sample Preservation & Transport Add HCl preservative upon return to lab Add HCl preservative upon return to lab Max of 48 hours on ice prior to preservative Max of 48 hours on ice prior to preservative Protect bagged samples from contamination during transport and storage Protect bagged samples from contamination during transport and storage Isolate or segregate samples as needed Isolate or segregate samples as needed

1669/ Conventional SFWMD; Analysis using pre-concentration CVAAS; MDL = 50 ng/L

Laboratory Design Considerations: Clean Bench vs. Clean Lab Cost vs. Type of Work Envisioned Cost vs. Type of Work Envisioned Workload Issues Workload Issues Sampling Bottle and Equipment Preparation Sample Preparation and Determinative Steps Fugitive Vapor Control Fugitive Vapor Control Particulate Control Particulate Control Instrument Location Instrument Location Without proper controls, spurious laboratory contamination can exceed water quality standards!

Instrument Schematic

Blanks in 1631  Blanks play a critical role in monitoring contamination, and quantifying the mercury content of samples  Mercury levels in (digested) method blanks may be higher than those present in ambient samples  Even the best de-ionized water has measurable concentrations of mercury  Digested blanks have Hg concentrations between 0.2 and 0.6 ng/L

Blanks in 1631E  Confounding of mercury levels in the reagent and the de-ionized water – cannot easily separate mercury content of reagents from mercury in de-ionized water  Assumption: Most of the “background contamination” in method blanks is from the reagents and not from the DI water  No “bubbler blanks” used in the automated method

Quantification in 1631E  Analyze 5 method blanks and calculate the blank correction  Subtract this “blank correction term” from all samples

Sensitivity Requirements Natural Waters Typical Levels: 0.5 – 2 ng/L THg < 0.02 – 0.2 ng/L MeHg Recommended Quantitation Limits: ~ 0.5 ng/L THg ~0.05 ng/L MeHg Discharge Monitoring Water Quality Standards: 12 ng/L THg Fresh 25 ng/L THg Marine Recommended Quantitation Limits: < 10 ng/L THg Fresh < 25 ng/L THg Marine

Detection and Quantitation Data Interpretation Detection and Quantitation Detection Limit and Quantitation Limits are Influenced by:  Sampling vessels, collection and handling techniques  Quality of the laboratory environment – particulate content of laboratory air  Cleanliness of digestion reagents and procedure  Instrumental technique

Recommendations Data Interpretation Recommendations  Conduct on-going, long-term detection limit studies rather than one-time studies;  Confirm all water quality exceedances with a separate analysis;  Use multiple method blanks with each analytical preparation batch;  Use rigorous quality control measures to ensure data integrity;