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A New Forensics Technique to Investigate the Presence of Chemical

“FingerPrints” in Human Breath

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Objectives

• Test Ability to Collect and Analyze Trace Level Chemicals in Human Breath

• Determine if Concentrations Increase upon Prolonged Exposure

• Determine Whether Trace Chemicals can be Detected in Breath Samples Days after the Initial Exposure

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Analyzing Volatile Organic Compounds in Breath

• Clinical Diagnosis– Elevated Organic Compounds– Isotopic Labeling

• Occupational Exposure Assessment

• Law Enforcement– Non-Invasive Monitoring for Drugs of Abuse– Breath Fingerprinting

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• The same mechanism that allows efficient transfer of O2 and CO2 through the alveoli also allows the exchange of other chemicals that are in the air as well

•Once in the blood, chemicals may metabolize readily, or may dissolve into adipose tissue where they may release back into the blood over time, allowing them to be detected in exhaled breath.

Chemicals in Human Breath as Forensic Tracers

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Requirements of Breath Testing Application

• Breath Sampling System

• Inert chemical storage device

• Effective (automated) analytical inlet system and GC/MS

• Multi-sampler decontamination system

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Selection of Sampling Device

• Choices: Tedlar bags, Adsorbent tubes, stainless steel canisters.

• Canisters advantages:– Ease of sampling (self contained

vacuum)

– Elimination of volume sampling errors

– Ability to recover reactive and thermally labile compounds

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SiloniteTM Coating Maximizes Inertness

• Silonite coating provides a highly inert surface preventing surface reactions that can occur on stainless steel

• Compounds that can be chromatographed can generally be stored in Silonite coated vessels.

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Last 20-30% of Exhaled Breath is Captured in Tube

The Breath Sample is Recovered into MiniCan without Introduction of Room Air

Breath Sampler Volume - 650cc

MiniCan Volume - 380cc

Collecting Breath Samples into MiniCans Breath Sampler Prototype

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2-Step Breath Sampling Procedure

1. Blow through disposable, check-valve to flush 0.65L tube volume

2. Connect evacuated MiniCan to recover breath sample

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Validating Proper Sampling of Breath

• Tetrafluoroethane released into room

• Participant inhales outside of room, walks into room and exhales through sampler

• Sampled breath introduced into can

• Second MiniCan filled with room air for comparison

0102030405060708090

100

TF

E C

on

c

RoomAir

Breath

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Low Volume Breath Sampler

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Laboratory Analysis

HP 5973 GCMS 7100 7032L 4600

7100 3-Stage Preconcentrator

7032L 21-Position MiniCan Autosampler

4600 Multi-Channel Standards Diluter

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GCMS

6

SplitCtrl.

VOC Breath Analyzer

7100 7032-L

SL I/O SL I/O

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CO2 and Water Elimination using Microscale Purge and TrapTM

InternalStandard

CalibrationStandard

Sample

Glass Beads Tenax

Cryogen in

CO2

Focuser

ToGC

VOCsH2O

Helium

PUMPMFC

Helium Carrier

Removing Water and CO2

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Decontamination System Allowing Unlimited Reuse of MiniCans

• Cleans MiniCans by Filling and Evacuating with Humidified Nitrogen.

• Testing one MiniCan after Cleaning Certifies all 21

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Testing Respiratory Adsorption and Desorption of VOCs

• Test Breath at t=0

• Expose Participant to chemicals at less than 5% of OSHA PELs for 8 hours

• Use personal MiniCan sampler (IH1200) to simultaneously collect air representative of what the participant is breathing

• Test participants breath at the end of the day

• Test participants breath on subsequent days

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Tracer Chemicals Released IntoRoom for 8 Hour Exposure

1. Hexane

2. 1,4-Dioxane

3. Methyl Methacrylate

4. n-Butyl Acetate

5. 1,3,5-Trimethyl Benzene

1

2

34

5

IS1

IS2 Sur1IS3

Sur2

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Chromatogram of Breath At Time=0 Hours

1 24 5

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Chromatogram of Breath At Time=8 Hours

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Single Ion Chromatogram of 1,3,5-Trimethylbenzene in Breath after 8 Hour Exposure

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Recovery of Chemicals in Breath

Run # Vol Taken Hexane 1,4-Dioxane Methyl Methacrylate n-Butyl Acetate 1,3,5-Trimethyl BenzeneOutside Air 99030301 400 7.31 3.78 1.63 2.60 1.79Breath @ t=0 99030302 400 3.75 27.68 0.25 0.95 0.28Breath @ t=8 99030303 400 73.07 9.65 0.77 3.85 2.02Breath @ t=24 99030304 400 2.88 1.16 0.19 0.22 0.18Breath @ t=48 99030402 400 1.35 0.54 0.17 0.33 0.12Indoor Air (IH1200) 99030305 50 124.60 9.73 85.56 38.83 1.1850 ppb Std 99030306 50 50.00 50.00 50.00 50.00 50.00

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Conclusion• Analytical methodology has been developed which allows

VOCs in human breath to be measured down to part-per-trillion levels

• Factors other than exposure levels appear to play a part in the concentration and lifetime of VOCs recovered in breath samples

• For this technique to be a practical forensics tool, the list of tracer chemicals would have to be somewhat unique. This may be the case in certain illegal drug manufacturing operations, although studies will have to be performed to substantiate this.