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Forensic Analysis and Sorbent Collection Methods MSRAS Soil Gas Sampling Workshop Indianapolis, IN August 21-22, 2006 PowerPoint Presentation
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Forensic Analysis and Sorbent Collection Methods MSRAS Soil Gas Sampling Workshop Indianapolis, IN August 21-22, 2006. Gina Plantz NewFields Environmental Forensics Practice, LLC gplantz@newfields.com 781-264-4950. Why use Forensics?.

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Forensic Analysis and Sorbent Collection Methods

MSRAS Soil Gas Sampling Workshop

Indianapolis, IN

August 21-22, 2006

Gina Plantz

NewFields Environmental Forensics Practice, LLC

gplantz@newfields.com

781-264-4950

why use forensics

Why use Forensics?

Ability to differentiate between sources of contamination

BTEX (benzene, toluene, ethyl benzene and xylenes) compounds are commonly used to determine the hydrocarbon source(s)

BTEX is present in many different hydrocarbon sources and more information is needed for definitive chemical fingerprinting

Ability to differentiate VI impacts from background sources

Common practices to deal with discerning background:

Building survey and product inventory

Using indicator compounds detected by standard methodology (e.g. Benzene, MTBE, isooctane, isopentane for gasoline constituents)

Compound ratio analysis of compounds detected by standard methodology between sub-slab and IA

forensic approach

Forensic Approach

Air method developed to “fingerprint” HC sources

Extended analyte list specific to hydrocarbons (93 compounds; PIANO, Thiophenes, Fuel Additives)

Analysis by GC/MS/FID

MS is run in simultaneous full SCAN and SIM modes

Reporting limits are 20-50 pptv

Ability to differentiate background from soil gas impacts

Ability to detect trace levels of target compounds in presence of high concentration samples

ertel sample collected from ss3d

Ertel Sample Collected from SS3D

Analysis by EPA TO-15:

TCE @ 55,000 ppbv

Large dilution needed for analysis, leading to majority of Non-detects for other targets

Analysis by Forensic TO-15:

Ability to analyze sample without dilution leading to sub ppbv RLs for HCs

ertel sample collected from ss3d5

Ertel Sample Collected from SS3D

TCE, 42 ppbv on column (55,000 total)

EPA TO-15

TCE

Benzene, 2.2 ppbv on column (22 total)

Forensic TO-15

ertel sample collected from p6

Ertel Sample Collected from P6

Analysis by EPA TO-15:

PCE @ 11,000 ppbv

Large dilution needed for analysis; few HCs detected leading and many non-detects for other targets

Analysis by Forensic TO-15:

Ability to analyze sample without dilution leading to fingerprint pattern and sub ppbv RLs

ertel sample collected from p67

Ertel Sample Collected from P6

PCE, 53 ppbv on column (11,000 total)

EPA TO-15

C5

Forensic TO-15

C6

C4

C7

T

PCE

MPX

124TMB

N

why use sorbent media

Why use sorbent media?

Many states have compounds of concern which only focus specifically on VOCs

114 compounds in Table 2 of OSWER Guidance

VOCs, SVOCs, PCBs, Metals

EPA TO-15 is only applicable for VOCs

Nothing heavier than Naphthalene

Sorbent collection/analysis methods necessary for all SVOCs

Sorbent types (PUF/XAD, Tenax, etc.))

what to look out for w sorbent collection

What to look out for w/sorbent collection

RLs are based upon the amount of sample volume collected

Sample volumes needed to meet screening criteria may not be practical for many screening levels

Sample duplicates are recommended at each point (TO-17)

Sample breakthrough may occur at high flow rates or with high concentrations

Recommended that tubes are placed in series when high concentration is expected

Samples must be chilled <4 C

sample volume needed to meet 10 6 shallow soil gas screening criteria oswer draft vi guidance 2002

Sample Volume needed to meet 10-6 Shallow Soil Gas Screening Criteria(OSWER Draft VI Guidance, 2002)

Slide courtesy of Severn Trent Laboratories

epa to 17

www.skcinc.com

www.sensidyne.com

EPA TO-17

Will be demonstrated tomorrow

Samples collected on a sorbent tube with use of pump

Collect duplicate samples per sampling point

Analyzed by GC/MS

Holding time is 14 days from collection

Must be chilled <4 C

svoc collection

SVOC collection

Picture courtesy of GeoSyntec

TO-13A:

PAHs and many other 8270

compounds;

TO-4A:

Pesticides & PCBs (including congeners);

PUF/XAD media for sample collection

Modified versions: low flow pump

Samples must be chilled <4 C

summary

Summary

Forensic techniques for VI assessments are an emerging and powerful tool

Forensic TO-15 showed the ability to report hydrocarbons to low ppbv RLs in presence of ppmv levels of chlorinated compounds

Forensic TO-15 was able to fingerprint a potential hydrocarbon source where standard TO-15 was not able to detect many hydrocarbons due to elevated PCE and TCE

Adsorptive media is needed for all SVOC collection

Current methods for SVOC collection and analysis may not be practical for meeting action levels