The Breathalyzer™

Presented By Lauren Mercier

What Happens to Alcohol in My Body After I Have a

Drink? Ethanol is immediately absorbed into

thecapillaries of body tissues and organs

When it enters the blood stream, ethanol is not metabolized and remains a separate component in blood flow

As blood flows across alveoli in the lungs, carbon dioxide molecules are exchanged for oxygen molecules

Ethanol evaporates from the blood into the breath since it is volatile, and is released with CO2 upon exhaling

+ CH3CH2OH

Relating Breath Alcohol to Blood Alcohol

The ratio of breath alcohol to blood alcohol is 2100 : 1, so 2100 mL of alveolar air contains the same amount of alcohol as 1 mL of blood

Blood alcohol content (BAC) can be calculated from the content of alcohol in the breath% BAC = g Ethanol x 2100mL Breath x 100% 52.5 mL Breath 1mL Blood

BAC of 0.08 means there are 0.08 g alcohol per 100 mL of blood

The Breathalyzer™

Measures concentration of alcohol in breath sample and determines BAC

Invented by Dr. Robert F. Borkenstein of Indiana State Police Department and has been on the market since 1954

Used to prosecute drunk drivers with BAC’s above legal limit of 0.08

Involves a “wet” chemistry reaction, modern models employ Infrared spectroscopy and fuel cells

Breathalyzer™ Apparatus Mouthpiece and thermostat set at 50°C +/- 3°C Sample chamber, contains piston that traps 56.5mL

breath and delivers 52.5mL breath to reaction mixture

Two sealed glass vials containing reaction mixture

H2SO4 (50 % by volume)

K2Cr2O7 (0.025 %)

AgNO3 (0.025 %) Light bulb between glass vials and photocells on

either side Meter connected to electrical output Alcohol scale

Collecting the Sample… The suspect blows into the mouthpiece

and their breath travels to a sample chamber

One glass vial neck is broken (test vial) and a glass tube, called a “bubbler”, is inserted

The operator turns a control knob to release the piston and force the sample through the bubbler into the test vial

Chemical Reaction

2 K2Cr2O7 + 3 CH3CH2OH + 8 H2SO4

2 Cr2 (SO4)3 + 2 K2SO4 + 3 CH3COOH + 11 H2O

AgNO3

If the Suspect Is Drunk… Ethanol in the breath reduces dichromate

ion to chromium ion The test vial lightens from pale yellow to a

bleached yellow colour, like weak lemonade More light passes through the lightened test

vial and hits a photocell causing electrical needle on meter to move

The operator turns a knob to balance needle and light moves away from test vial

When the needle is centered the operator reads alcohol meter to determine BAC

The Intoxylizer™

Uses Infrared spectroscopy to detect ethanol (C-O, O-H, C-H, C-C bonds)

IR energy passes through sample chamber containing breath sample and then through narrowband IR filter

Filtered energy focused on photocell detector which converts it to electrical pulses

Microprocessor interprets pulses and calculates BAC  

Quartz Lamp

Breath Sample In Breath Sample Out

Sample Chamber

Lenses

Filter Wheel

Photocell

Microprocessor

Examples of Alcohol Detecting Devices

Intoxylizer® 8000 uses IR spectroscopy

Intoxylizer® 400 uses electrochemical fuel cells

Fuel Cell Detectors Apparatus consists of two platinum electrodes

with acidic electrolyte material between them Ethanol in breath oxidized at surface of anode

to give acetic acid, protons, and electrons Atmospheric oxygen reduced at cathode to

give two oxygen atoms Protons and electrons from anode travel to

the cathode and combine with oxygen to form water

Movement of electrons produces a current that is proportional to the amount of alcohol in the breath sample

Microprocessor measures the current and calculates BAC

In Conclusion… There are several methods available for

forensic alcohol testing Now there are hand held breath alcohol

testers to take on site or to parties to decrease the number of people who drink and drive

Results provide evidence in DWI trials Results can be inaccurate because of

temperature changes and varying blood to breath ratios

Tests are non-invasive and fairly accurate but require a trained operator

References http://science.howstuffworks.com/framed.htm?parent=breathalyzer.

htm&url=http://nydwi.com/dwiqanda/ http://www.occid.org/legislation/bac-priority.pdf http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookRESPSYS

.html#The%20Human%20Respiratory%20System http://science.howstuffworks.com/framed.htm?

parent=breathalyzer.htm&url=http://nydwi.com/dwiqanda/ http://www.craigmedical.com/Breathalyzer_FAQ.htm http://www.alcoholtest.com/ecfuel.htm http://www.alcoholtest.com/ir.htm http://www.druglibrary.org/schaffer/Misc/driving/s5p4.htm http://www.lion-breath.com/serv01.htm Labianca, Dominick A. “The Chemical Basis of the Breathalyzer: A

Critical Analysis”, Journal of Chemical Education. (1990). 67(3). 259-261.