Breath Alcohol

• Author: James G. Wigmore
• Pages: 104-177

 

 

breath Alcohol

Breath alcohol analysis is commonly used in law enforcement as it has

many advantages over blood alcohol testing:

• Breath alcohol testing is noninvasive. No needles are required to

collect blood; hence, there is no possibility of injury or transmis-

sion of disea se.

• The breath alcohol results are known im mediately, as opposed to

the several days or even weeks needed for blood results to be re-

ported by forensic laboratories. The police are therefore immedi-

ately aware of what charge to lay and whether medical treatment

may be required for the drink ing driver (e.g., alcohol poisoning).

• Breath alcohol correlates better with brain a lcohol concentration

(arterial blood) and gives a better indication of impairment due to

alcohol duri ng the rising blood alcohol concentration (BAC) pha se.

• There are no continuity or storage and transpor tation issues. The

breath sample is provided directly into the breath alcohol instr u-

ment. No special blood tubes, swabs, identity seals, biohazard

refrigeration, or special transportation is required, as for blood

samples.

• No medical staf‌f or phlebotomists a re needed for breath alcohol

analysis. The breath tests may be conducted at the police station

or mobile van, allowing the time bet ween the arrest and testing

to be reduced signif‌icantly.

• There is no problem with a real or alleged blood or needle phobia

of the arrested driver.

Breath Alcohol  

Reference Number: 

This chapter deals w ith the many issues that arise in cr iminal court,

such as the ability to provide a suitable breath sample, the blood-breath

ratio (BBR), the mouth alcohol ef‌fect, and the specif‌icity of breath alco-

hol tests.

3.01 METHODS OF ANALySIS, DuPLICATION, AND

TRuNCATION OF RESuLTS

Breath alcohol detection technology has changed dramatically over the

more than  years since the Breatha lyzer (using a wet chemical method)

was f‌irst introduced (, ). The chemical reaction that was the

basis of the Breathalyzer was based on potassium dichromate (a yellow-

orange color) and sulfuric acid reacting with alcohol to form chromic

sulfate (a blue-green color), potassium sulfate, acetic acid, and water as

follows:

KCrO + HSO + CHCHOH →

Cr(SO) + KSO + CHCOOH +   HO

Electrochemical (fuel cell) sensors (–) also convert alcohol

into acetic acid but measure the electric current generated rather than

a colour change, as with the Breatha lyzer. Other devices use infrared

(IR; –) or a combination of the IR and fuel cells () to detect

breath alcohol. The n-type semiconductor (Taguchi) detector has been

found not to be suitable for evidential or even screening applications

(). Future methods of detection of alcohol may include portable

mass spectrometry (MS; ) or full IR spectrum scan (). The

dif‌ferences between two successive breath tests and the truncation of

breath test results are also di scussed in this section (–).

Reference Number: 

, ..,  .. . “The Breathalyzer and Its Applications.”

Medicine Science and the Law, : –,  ( f‌igures,  references)

Abstract: The Breathalyzer, the most successful a nd widely used instr u-

ment for the medicolegal determination of alcohol in the breath, was

designed and developed by R.F. Borkenstein in . It was based on the

photometric measurement of the decrease in yellow color of potassium

dichromate solution in reaction with alcohol.

  Wigmore on Alcohol

Reference Number: 

The oxidation of alcohol using acid dichromate forms the basis of most

of the available methods for the determination of alcohol. A degree

of specif‌icity for certain react ants is obtained through the choice of

conditions. Using KCrO in % by volume HSO at ºC or at room

temperature with a suitable catalyst, alcohol is quantitatively oxidized

to acetic acid within  seconds. Variations in acid concentration (plus

or minus %) or time (between  and  seconds) do not appreciably

alter the results. The instrument autom atically compensates for varia-

tions in the KCrO content of the solution.

Reference Number: 

, .. “The Accuracy Reliability and Validity of the Breathalyz-

er.” Australian New Zealand Journal of Criminology, : –,  (

tables,  references)

Abstract: In this study,  male subjects consumed  mL/kg of % v/v

(volume of solute per volume of solvent) ethanol mixed with lime juice.

Drinking wa s to be completed within  minutes. To prevent nausea,

subjects were allowed to eat a few dry biscuits. T hirty minutes after the

subjects f‌inished drinking, a breath sample was taken from each, and

 minutes later a blood sample was taken. The BAC range was .–

.g/mL. The correlation (r) between blood and breath was ..

A second breath sample was taken in  subjects as close as possible

to the taking of the blood sample. The greatest time dif‌ference was 

minutes. The correlation with blood was .. The largest false high

dif‌ference was a Breathalyzer result of .g / mL and a BAC of

.g/mL.

The results of this experiment indicate that the B reathalyzer can be a

reliable instrument in assessing a perso n’s BAL [blood alcohol level]. It is

true that the apparatus was operated under ideal phy sical conditions by

a highly skilled police ocer and that the breath samples were collec ted

from co-operative subjects who h ad drank relatively low quantities of

alcohol.

Reference Number: 

, .., .. , .. ,  .. . “Electrochemical Meas-

urements of Blood Alcohol Levels.” Nature, : –,  ( f‌igure,

 references)