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Most people think ethanol is an amazing substance that
relieves their stress and negative feelings. However, this psychoactive
substance can dictate whether or not a person will receive consequences with
the law. The amount of people that are drinking and driving is increasing, and
tests are being improved to detect whether a person is under the influence of


After the consumption of ethanol, it is absorbed by the
gastrointestinal tract. The ethanol is then transported throughout the body and
into the blood. Most of the ethanol is broken down in the liver. The other traces
of ethanol can also be found in the urine, when your body eliminates it, and it
can also be found in your breath, from your lungs during exhalation. It can be
measured within minutes of alcohol consumption. Since these three places are
the easiest to find ethanol in the body, these are the three most common tests
performed to determine a person’s ethanol content. Blood and urine tests must
be sent to a lab to be analyzed, whereas a breath sample can be performed on
site and the results are immediate.

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To perform a blood test to determine the ethanol content, an
elastic band will be wrapped around your upper arm; this will stop the flow of
blood. This causes your veins to pop out more, so that a needle can be placed
into the vein. Once the needle is placed into the vein, a tube is attached. The
tube is then filled with blood from the vein. Once the tube is full, the band
on your arm is removed. Immediately after the band is removed a cotton ball is
placed over the needle site while the needle is removed. Pressure is placed on
the site and a bandage is placed on the site. The results will either appear
“normal”-no alcohol is found in the blood, or “abnormal”-any alcohol is found
in the blood. It will also show the estimated blood alcohol concentration.
Legal intoxication is considered to be having a blood alcohol concentration of
0.08 or higher, which is considered to be 80mg/dL or 17mmol/L. The problem with
using blood tests to determine the ethanol content in the body can be with the
collection of the blood or the storage of the sample. Studies have shown that
errors with the blood draw can lead to false positives up to 50% of the time.
Also, the area where the blood is stored before the analysis can also lead to a
false positive. Whether it’s improper storage, delays, or change in
temperature, there are many errors that can occur before the blood gets
analyzed. Another problem with the blood testing is that not everyone can have
it done since other factors may get in the way of the results. For instance, if
someone has high blood ketones, as in diabetic ketoacidosis, or if someone is
taking cough medicines that have alcohol in it, or if someone drank alcohols
other than ethanol, such as isopropyl alcohol or methanol. Also, using rubbing
alcohol on the skin before inserting the needle could even have a slight effect
on the results.


When a urine test is performed, it examines the physical,
chemical, and microscopic components of the urine. The urine is collected into
a specific container. The container is free of interfering substances, has a
secure lid, is leak-resistant, and is made of break-resistant plastic instead
of glass. It has a wide base to prevent spillage, secure closures that will
prevent the loss of the specimen, and the container is amber coloured for
light-sensitive analytes. One of the main testing methods for determining how
long alcohol has been in your system is called “EtG” (Ethyl Glucuronide), which
is a biomarker. The results can show if alcohol has been ingested within the
last 80 hours, which can be as long as 3-4 days. This is why the EtG test is
also called the “80 hour test.” If EtG is found in the urine, then it is an
undeniable indicator that ethanol had been ingested. Ethyl Glucuronide is a
direct metabolite in alcohol, and the EtG test detects its presence in urine,
to determine if there had been alcohol consumption recently. The problem with
this test, is that it can’t determine how much alcohol a person has ingested,
if it has impaired their judgement, or if they are currently under the
influence of alcohol, it can only determine whether a person has ingested
ethanol within the past 80 hours. Typically, urine alcohol tests (EtG tests)
are used for child custody cases, drug court cases, employee screening in the
workplace, and making sure people on probation are not consuming alcohol. Urine
tests are not usually performed when determining if someone is driving under
the influence because it is too difficult to relate the urine concentration of
alcohol to the legal blood alcohol limit. 
The rate of alcohol metabolization in the body is about 0.012-0.015 of
blood alcohol concentration per hour, so if you were at the limit (0.08%), then
it would take approximately 5 and a half hours for all the alcohol to leave
your body. This is why urine tests can be useful; it can detect alcohol
consumption long afterwards even when the other methods, such as by blood and breath,
can no longer detect the ethanol.



There are different types of tests used to determine the
amount of ethanol found in a person’s breath. Two of them include a
Breathalyzer and an Intoxilyzer.

A Breathalyzer is the most common method for determining the
amount of ethanol in someone’s body. A Breathalyzer is a device that a suspect
breathes in to. There are two vials on it, and when blown into, the breath
sample goes into one vial and bubbles through a mixture of sulphuric acid,
potassium dichromate, silver nitrate, and water. A chemical reaction then
occurs, and that’s the main measurement that is used. In the reaction, the
alcohol is taken from the air and put into a liquid solution by sulphuric acid.
Then the alcohol and potassium dichromate form a reaction. When this reaction
is occurring, the red/orange dichromate ion will change colour to the green
chromium ion once it reacts with the alcohol. The amount of alcohol released
into the air is directly related to the change in colour. To calculate the
amount of alcohol that is in that air, the reacted mixture and an unreacted
mixture are compared in a photocell system, and this will produce an electric
current causing the needle in the meter to transfer from the start area. The
worker performing the test will move the knob to make the needle go back to the
start position. The more the worker needs to turn the knob to make the needle
go back, the higher the alcohol level. Although breathalyzers are the easiest
method for BAC testing, they are not always accurate. Factors such as diet,
metabolism, body temperature, vomiting, mouthwash, and breath mints can create
inaccurate results.

An Intoxilyzer detects ethanol by infrared spectroscopy. To
do this, the chemical properties of the ethanol molecule are important. The
chemical bonds between the Carbon, Hydrogen, and Oxygen atoms, the shared pairs
of electrons, and the ways the bonds can bend and stretch are important in
detecting ethanol in a sample through infrared spectroscopy. The Intoxilyzer
device identifies molecules by the way they absorb infrared light. The
vibrations of the molecules change when infrared light is absorbed. The
stretching and bending of the chemical bonds are included in the vibration
changes. Since the absorption occurs at different wavelengths, to find ethanol
in a sample the wavelengths of all the bonds in ethanol must be looked at, plus
we must measure how much infrared light was absorbed. The different bonds in
the ethanol molecule include C-O, O-H, C-H, and C-C, and these are the bonds
that are an important part of the Intoxilyzer method. The wavelengths show
whether or not ethanol is present, and the amount of infrared absorption shows
the amount of ethanol present.


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