TOXICOLOGY PART II

Alcohol

Field Sobriety Tests

Officers have the right to ask individuals who are suspected of being under the influence to take field sobriety tests

National Highway Traffic and Safety Administration 3 official tests Examine driver’s coordination, balance, and

dexterity Walking in a straight line and turning around Standing on one leg while counting Horizontal gaze nystagmus

Methods of Alcohol Detection in Breath

3Types: Breathalyzer – Colorimetry/Spectrophotometry

Reduction of dichromate to chromium producing a color change from orange to green

Intoxilyzer – Infrared spectroscopy Absorption of infrared waves by alcohol

Alcosensor – Fuel cell technology Reduction of alcohol to acetic acid by a platinum

catalyst. This produces a measureable electrical current.

The Breathalyzer Reaction

In the field, this semi-quantitative test can be easily used.

When breath containing alcohol is exhaled into the blue end of the device, it reacts with the dichromate. More green means a higher BAC.

Some Popular Breathalyzer Myths

Myth: Chewing on coffee grounds, eating onions, using breath mints will help you pass a breathalyzer test

Fact: Good or Bad breath does not have any impact on the test

Myth: Placing pennies or batteries in your mouth before being tested

Fact: No effect on the test

Myth: Hyperventilating before being tested

Fact: Actually increases your BAC by as much as 20%

Lit, but not the Brightest Bulb

To beat a possible DUI, this man ripped apart his underwear in the back of a police car and began to eat them thinking that the cotton would absorb the alcohol.

He was latter acquitted in court because his BAC was not over the legal limit.

People had to be removed from the court room because they had difficulty trying to contain their laughter

Spectrophotometry

Spectrophotometry is a method used to measure the amount of a chemical substance by measuring the intensity of light that passes through a sample solution.

Components of a Spectrophotometer

Color and Spectrophotometry

Objects absorb only certain wavelengths of light. Those that are not absorbed are transmitted or reflected. The transmitted or reflected wavelengths are those that we see.

100% Transmittance0% Absorbance

0% Transmittance100% Absorbance

Creating a Standard Curve for Ethanol

Several standard solutions containing a known concentration are reacted with the dichromate reagent.

Samples are placed in the spectrophotometer and their % absorbance is measured. (one of the standards always contains 0% ethanol)

A graph is created by plotting % absorbance on the y-axis and ethanol concentration on the x-axis.

Determining the Concentration of Ethanol in an Unknown Sample

After creating a standard curve, measure the absorbance of the unknown sample and compare to the curve.

An absorbance of 0.5 = 0.55% Ethanol

PA DUI Regulations

DUI - Driving Under the Influence (DWI, OUI, OMVI, DWAI, DWUI, DUIL, DUBAL)

Penalties Jail time License suspension Fines

Legal Limits 21 and over – 0.08% Under 21 – “Zero Tolerance” - 0.00 -0.02% Commercial vehicle operators – 0.04%

** Over 56,000 arrests for DUI in PA last year**About 12,000 crashes and 400 fatalities