Blood Breath & Tears XVISeptember 24-25, 2009

How to Deal With Blood Alcohol Evidence

Stefan Rose, M.D.

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AcknowledgementsHal SchuhmacherRichard Hersch

Kathryn Bradley

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Stefan Rose, M.D. e-mail toxdoc@umfc.net

University Medical and Forensic Consultants, Inc.10130 Northlake Boulevard Suite 214 - 300

West Palm Beach, Florida 33412

Phone (561) 795-4452 Fax (561) 795-4768

Toll Free 1-800-555-6449

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Stefan Rose, M.D.c.v. snapshot

Forensic PhysicianTrained in Forensic Toxicology and Psychiatry

First Director of the DUI Lab @ the University of MiamiPractice in Forensic Medicine and Courtesy Professor,

Department of Chemistry, FIU, Miami, FLResearch Projects include:

Forensic Reliability of Breath Alcohol TestingAlcohol Effects on Eyewitness Memory

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How to Deal With Blood Alcohol

Evidence

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Today’s Talk Blood

1.The Human Tissue 1.The Forensic Specimen

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Blood Alcohol Analysis1. Gas Chromatography

2. Enzyme Assay

Today’s Talk

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Interpretation of

Blood Alcohol Results

Today’s Talk

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Today’s Talk Summary of Errors in Blood Alcohol Testing

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Blood The Human Tissue

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http://www.nsbri.org/HumanPhysSpace/focus3/fig2.jpg

Hemolysis

NORMAL

Lipemia

NORMAL

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Jaundice

NORMAL

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Blood samples vary in composition from person to person, and vary in composition

within the same person depending on their condition (fasted, fed, hydrated, dehydrated, healthy, sick and so on)

These differences in blood composition may cause errors in the blood alcohol test

result depending on the test method.

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BloodThe Forensic Specimen

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Obtaining the Blood SampleN.I.K. Tri Tech

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N.I.K.

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Tri Tech

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Sodium Fluoride (NaFl) is a preservative, and is required to prevent

fermentation of the blood sample

No quality control procedures exist to detect fermentation in an FDLE

blood sample

100 mg of Sodium Fluoride is recommended as the minimum amount in a 10 ml tube of blood – some authors

recommend 200 mg

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1. The blood kit manufacturers do not make the blood tubes and therefore cannot prove the forensic reliability of the tubes

2. The State may lose their presumption if they cannot get direct testimony from the tube manufacturer

3. Incredibly, the wrong tubes with not enough sodium fluoride may have been used to collect the blood sample!

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Steps to Follow 1. Identify the Subject2. Inspect Blood Kit3. Apply Tourniquet4. Identify Blood Vessel5. Disinfect with Iodine6. Perform Venapuncture7. Remove Tourniquet8. Label and seal Tubes, Box9. Complete Paperwork

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An example of a properly sealed blood tube

Improperly sealed tubes

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Selecting a Blood Vessel

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Most Common Site For Blood Draw

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Trauma Blood Draws from the Femoral Artery

Most femoral blood draws are

arterial blood samples!

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What is wrong with this sample?

Arterial blood may be up to 40% HIGHER in blood alcohol

concentration compared to venous blood!

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Blood Alcohol Errors So Far1. Non – compliance with Implied Consent2. Chain of custody errors3. Forensic Blood Collection Kit error4. Arterial instead of venous blood5. Contamination with fermenting microbes

Implied consent

Blood Alcohol AnalysisGas Chromatography

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The analysis of any unknown sample includes:

1.Qualitative analysis2.Quantitative analysis

Chromatography was first developed by the Russian botanist

Mikhail Tswett in 1903

Chromatography is a chemical technique that separates a complex mixture of compounds one

from another so that each compound may be analyzed individually without interference from

the other compounds in the mixture

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Regarding Blood Alcohol Analysis the complete designation for the chemical

technique is:

Static Headspace Gas Chromatography

with Flame Ionization Detection

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Most of us refer to it as

GC-FID

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Chromatographyis also known as Separation

Science

Schematic Diagram of Gas Chromatography

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Complete GC-FID System44

How Does the GC-FID Analysis Occur?

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Let’s start with the sample

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What Types of Test Samples may be analyzed?

1.Blank2.Negative Control3.Positive Control

4.Calibrator5.Unknown Sample

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What Types of Biologic Samples may be analyzed?

1.Blood2.Plasma3.Serum4.Urine

5.Ocular

Blood sample is diluted0.10 ml blood1.0 ml water

Headspace sample taken for analysis

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Complete GC-FID System50

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Sample injectorFID detectors

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Schematic Diagram of Gas Chromatography

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Restek BAC Column

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What does the GC raw data look like?How is ethanol identified?

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1000

2000

Typical GC-FID Chromatogram

blank

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0

1000

2000

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injection peak

response

Typical GC-FID Chromatogram

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1000

2000

one compound

internal standardn-propanol

negative control

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response

injection peak

injection peak

Typical GC-FID Chromatogram

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1000

2000

two compounds

internal standardn-propanol

ethanol

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response

injection peak

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Internal Standard

n-propanol

injection peak

ethanol

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injection peak

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What happens if two different compounds have the same retention time?

co-elution

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How is the co-elution error prevented with GC-FID analysis?

Dual Column Analysis

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How is ethanol quantitatedwith GC-FID analysis?

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0.02 gram/dl

0.05 gram/dl

0.08 gram/dl

0.20 gram/dl

0.30 gram/dl

0.10 gram/dl

Ethanol Calibration Curveinstrument response

concentration

UNKNOWN SAMPLE ANALYZED

0.15

0.02 gram/dl

0.05 gram/dl

0.08 gram/dl

0.20 gram/dl

0.30 gram/dl

0.10 gram/dl

Ethanol Calibration Curve

instrument response

concentration

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Blood Alcohol Errors So Far1. Whole blood not used2. Negative control contaminated3. Sample mix-up in autosampler4. Fermentation in incubator5. Co-elution with single column GC6. Poor calibration curve

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Enzyme AssayAn enzyme is a special protein that speeds up a biochemical reaction

alcohol dehydrogenase

adh

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Ethanol enzyme assay measures NADH, NOT ethanol!!

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1. Hospital serum ethanol testing performed for medical, not legal purpose

2. No chain of custody – the sample results may belong to another patient

3. No sample available for independent re-test by opposing side

4. Serum ethanol result always higher than whole blood ethanol result

5. Hospital blood draw may obtain arterial blood instead of venous blood

Hospital Ethanol Enzyme Assay Test Errors

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1. Arterial blood may be 40% higher in ethanol concentration vs. venous blood

2. Hospital chemistry analyzers can cause false positive results

3. Hospital protocols do not follow forensic quality control guidelines

4. Hospital serum ethanol quantitative error is plus or minus 25%

5. Serum ethanol enzyme assay method prone to false positive results

Hospital Ethanol Enzyme Assay Test Errors

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Interpretation of

Blood Alcohol Results

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Typical Blood Alcohol Concentration Curve

BAC

Time (hours)

Blood sample @ 7:00 0.12 g/dl0.12

0.14

Predicted BAC @ 6:00 0.14 g/dl

absorption

peak

elimination

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What Does the Blood Alcohol Curve

Look Like in a Social Drinking Setting?

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The Assumptions Regarding Social Drinking and BAC’s at a Given

Point in Time by State’s Witness are Not Supported by the Evidence!

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Summary of Errors in Blood Alcohol Testing

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1. Non – compliance with Implied Consent2. Chain of custody errors3. Forensic Blood Collection Kit error4. Arterial instead of venous blood5. Contamination with fermenting microbes

Forensic

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1. Whole blood not used2. Negative control contaminated3. Sample mix-up in autosampler4. Fermentation in incubator5. Co-elution with single column GC6. Poor calibration curve

Forensic

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1. Hospital serum ethanol testing performed for medical, not legal purpose

2. No chain of custody – the sample results may belong to another patient

3. No sample available for independent re-test by opposing side

4. Serum ethanol result always higher than whole blood ethanol result

5. Hospital blood draw may obtain arterial blood instead of venous blood

Hospital Ethanol Enzyme Assay Test Errors

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1. Arterial blood may be 40% higher in ethanol concentration vs. venous blood

2. Hospital chemistry analyzers can cause false positive results

3. Hospital protocols do not follow forensic quality control guidelines

4. Hospital serum ethanol quantitative error is plus or minus 25%

5. Serum ethanol enzyme assay method prone to false positive results

Hospital Ethanol Enzyme Assay Test Errors

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Thank You!

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