Michael Gershenzon

bcnys.org

Michael Gershenzon

Alcoa Inc.

Technical Challenges with PCB Analysis

Michael Gershenzon November 18, 2010

Alcoa Technical Center, PA


Outline

Introduction

-PCBs

- Current PCB Sources

- Background PCB Levels in the Environment

- Analytical Methods for PCB Detection

- Historical Notes on Method 1668

Three Case Studies – Importance of Site-Specific

MDL Determination

- Case Study 1: Site-Specific MDL Study for EPA

Method 608

- Case Study 2: Inter-laboratory Comparison of MDLs

for Method 1668A

- Case Study 3: Comparison of PCB Analysis Results

Obtained by Methods 608 and 1668A

Conclusions

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Introduction – What are PCBs?

Polychlorinated Biphenyls (PCBs):

209 individual congeners

Man-made chemicals started to be released into the

environment in 1900’s

• Estimated that > 1.5 bn lbs. manufactured in the US before 1977

Formerly used in a variety of industrial applications (electric

components, hydraulics, heat transfer systems, flame

retardants, etc.)

Production banned in late ‘70s due to toxicity, but still

ubiquitous in environment due to persistence (thermal and

chemical stability)

3


What are the Current PCB Sources?

PCBs used many years after production ban

Dielectric oils considered hazardous waste

PCB > 50 ppm

Stormwater runoff

• Contaminated sites

• Leaking transformers

Sediment “hot spots”

Atmospheric Deposition

• Contaminated sites off-gas

• Combustion of contaminated recycled oil

• Rainwater contribution to “background” PCBs => surface waters

4


Example: PCB Concentrations in Rainwater (ng/L, ppt)

(Great Lakes)

Source:Polychlorinated Biphenyls in Chicago Precipitation, Env. Sci. Techn., 1997

5


Example: PCB Concentrations in Human Blood Plasma

(g/L, ppb)

1-15 ppb

Geometric mean PCB concentration in g/L (ppb)

Source: AMAP Assessment Report: Arctic Pollution Issues 1998

http://www.amap.no/?main=http://www.amap.no/mapsgraphics/go/collection/amap‐assessment‐report‐arctic‐pollution‐issues

6


Analytical Methods for PCB Detection

EPA Method 608 - Currently in use for SPDES compliance

GC/electron capture detector instrument

Measures Aroclors (mixtures of congeners, e.g. Ar. 1248 – 48%

chlorine)

The only EPA-approved method for use in NPDES permit program

Method Detection Limit (MDL) range 10 – 100 ng/L (ppt)

Cost per sample ~ $50/sample

EPA Method 1668 – Proposed for use in SPDES compliance

High Resolution GC/MS Method

Capable of detecting individual congeners

EPA-estimated Method Detection Limit Range: 0.004 – 0.45 ng/L

(ppt)

Cost per sample ~ $1,000/sample

7


How Many Grains of Salt are in 1668?

ppm (mg/L) ppb (g/L) ppt (ng/L) ppq (pg/L)

Method

608

Method

1668

2,315 Lb.

(1.16 Tons)

2.3 Lb

(0.002 Lbs)

(1 gm)

(0.000002 Lbs)

(1 mg)

3,000,000,000 3,000,000 3,000 3

grains salt grains salt grains salt grains salt

0.5 mile

5 Ft.

Water

Vol. ~277 million gallons


Can You Find a Cowboy in Texas?

1 ppq area of a cowboy hat

relative to the territory of Texas

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Method 1668 Historical Notes

Published by EPA in 1999 (Revision A)

Inter-laboratory Validation Study conducted by EPA in 2003 – 2004 (14

labs participated):

• 11 labs submitted data

• 5 labs submitted data deemed unusable by EPA; Data from six labs was accepted

• Evidenced lab to lab variability in method implementation (utilizing smaller sample

volumes, diluted final extracts, misinterpretations of QA requirements)

• Final report published in 2008 (Revision B issued)

Inter-laboratory study conducted by GE and Env. Standards in 2008:

• Spiked (0.3 – 45 ppt) natural water samples submitted to three labs

• Significant lab-to-lab data variability (~order of magnitude)

EPA’s Lower Passaic River Oversight Program (2008):

• Two labs

• Matrix – River Sediments

• Only samples with PCBs > 5X quantitation limit were used in the statistical analysis

• High variability in results - 320 out of 1500 split samples had congener specific

result RPD’s >30%

• This amount of variability is concerning when reporting results from different labs at

or near compliance goals (which numbers do you use?)

10


Method 1668 Historical Notes (cont’d)

Proposed for approval by EPA (1668C, 2010)

http://www.epa.gov/waterscience/methods/update/

Once approved, regulated parties may be required to use

1668 (instead of 608) under the “sufficiently sensitive” method

doctrine http://edocket.access.gpo.gov/2010/2010-15254.htm

What would the data quality be like?

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Case Study 1 /Alcoa/:

Method 608 Site-Specific MDL

‣ Conducted at an Alcoa location

‣ Site‐specific water used in the study (stormwater)

‣ Study conducted as outlined in 40 CFR Part 136 Appendix B

Effluent sample

grab (50 gal)

Sample

split into 7

Spiked with

Aroclor 1248

(20, 50, 75,

100, 175, and 300 ppt)

Split into

7 repeats

49 samples

submitted blind

for analysis

Lab‐reported MDL using reagent‐grade water = 10 ppt

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20 ppt Spike Results

Lab MDL

5 out of 7 samples spiked at 20 ppt Aroclor were reported as below DL..

13


300 ppt Spike Results

MDL = 56 ppt, calculated according to 40 CFR 136 Appendix B

14


Method 608 Site-Specific MDL Study Results Summary

100

80

Site Specific MDL

MDL (ng/L)

60

40

20

3 out 7 < DL

52 out out of 7 7 < < DL DL

3 out 7 < DL

0 out of 7 < DL

0 out of 7 < DL

Original Method MDL

0 out of 7 < DL

0

0

50

100

150

200

250

300

Aroclor Spike Concentration (ng/L)

Original MDL = 10 ppt; Computed MDL = 82 ppt – 99% upper confidence limit

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Case Study 1 Conclusions

The inability to detect PCBs spiked at 75 ppt and

below suggests an MDL < 75 ppt is inadequate

Each computed MDL (using site-specific water)

exceeds lab-reported MDL = 10 ppt (using reagent

grade water)

Computed MDLs allow the plausibility of an MDL as

high as 82 ppt, the 99% confidence limit..

Relative variability would be accentuated for 1668

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Case Study 2: Inter-laboratory

Comparison of MDLs for Method 1668A

10 5

10 4

608 MDL/S‐S MDL range

Lab A; Avg = 2.0 ppq;

Lab B; Avg = 3.8 ppq;

Lab C; Avg = 50.4 ppq;

EPA Estimated MDL; Avg = 178.5 ppq;

Method 608 MDL Range

MDL (ppq)

10 3

10 2

10 1

10 0

10 -1

0

20

40

60

80

100

120

Congener Number

140

160

180

200

April 2010

Significant (up to ca. 2 orders of magnitude) discrepancy in lab-reported MDLs

What is this discrepancy due to? Method implementation, etc.? Which lab to use?

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Case Study 2 Conclusions

Up to 2 orders of magnitude difference in lab-reported MDLs

Lab MDL studies can provide unrealistically low “optimized”

MDLs:

- one analyst - all samples run on one day

- one instrument - ideal conditions

looks good for competing laboratories, but does not

describe routine lab capability

Reporting of positive results based on “super low” MDL studies

can result in NPDES permit violations when, in reality, the

reported detection is instrument noise

Example of an unrealistically low MDL presented in Case Study 1

18


Case Study 3 /Alcoa/: Method 1668A vs

608 Results Comparison

Water samples collected at 8 different outfalls and internal sampling locations.

Submitted for parallel analysis by 608 and 1668A.

19


Example of 1668A Analysis Report

Oneway Analysis of Conc (ng/L) by Congener; Site = Alcoa; Homolog = 4

Actual reported data

zeros are neither reportable values nor a valid detection limit..

20


Potential Issues with Inadequate

Analytical Techniques

The average value and variability for the observed concentrations in surface waters have reduced

dramatically..

“Earlier limitations were caused more by [sample] contamination than by inadequate detection limits..”

Source: W. Fitzgerald. Sci of Tot. Env., 87/88, p. 223, 1989 and N.S. Bloom, National Forum on Mercury in Fish.. 1995

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Sample Collection and Handling

Requirements for ppq-Level Analysis

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Summary

10 5

Measured

MDL

ppb

PCB concentration (pg/L)

10 4

10 3

10 2

10 1

10 0

10 -1

What is a realistic MDL for 1668?

What is an upper bound on the noise level?

False Georgia positive/negative identifications?

How do you conduct a site‐specific MDL Study for 1668?

Alabama

- congeners?

- Aroclors?

- spiking levels?

- background levels?

St Lawrence - blanks?

How high is the cost?

WQBEL/

WQS

Human

PCBs in

health

St. Lawrence

criteria

(Canada)

PCBs in

rainwater

(G. Lakes)

EPA

Lab A

Lab C

Lab B

Lab MDL

1668 Lab 608 MDL

MDL

Comparison of PCB water criteria, h.h. criteria, river, rainwater, and method MDL levels

ppt

ppq

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Acknowledgements

Alcoa: D. Belleau, D. Coleman, T. Lightfoot, C. Dobbs, J. Morton, R.

Dworek, J. Lease, and J. R. Smith

Environmental Standards, Inc.: David Blye

Contact: Michael Gershenzon, michael.gershenzon@alcoa.com

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