The Law and Science of DataMaster Breath Testing

History:

The study of using breath to test the amount of alcohol in one’s blood probably began with the research of Dr. Emil Bogen who reported measuring blood alcohol concentration (BAC) by analyzing a persons breath.  In 1938, Professor Rolla Harger invented a device called a “Drunkometer”.  In 1954 Dr. Robert Borkenstein invented the first of the more modern breath testing instruments, the Breathalyzer.  The DataMaster was designed in 1985.

Basics of Alcohol Physiology:

Beverage alcohol (ethanol) generally enters the body through the mouth, and absorption of the alcohol begins almost immediately. Most of the absorption occurs in the stomach and because of ethanol=s affinity for water, it is rapidly distributed throughout the body by the process of diffusion.  Upon reaching equilibrium the fluids of the body will contain ethanol in proportion to their water content. In 1932 a Swedish scientist named E.M.P. Widmark published a his novel research addressing the issues of alcohol’s absorption, distribution and elimination in human subjects.  This research still forms the basis for alcohol calculations performed in today’s courtrooms. Widmark found that because of alcohol’s unique characteristics, certain assumptions can be made relative to the manner in which a person will absorb alcohol, how this alcohol will be distributed throughout the body, and how it will eventually be eliminated. The essential problem with the Widmark formula is that there are individual differences in each of these functions, and scientists differ in their opinions relative to the amount of certainty that can be assigned to a BAC derived through the use of this formula.

Perhaps the core problem is the length of time that is required for full aborption to occur. Dubowski’s position is best summed up in his in his 1976 article “Human Pharmacokinetics of Ethanol. I. Peak Blood Concentrations and Elimination in Male and Female Subjects”, Alcohol Technical Reports, Vol 5, No. 4, 55-63 (1976) where he indicates that full absorbtion usually uccurs between 15 and 137 minutes after drinking.  During the absorptive phase, breath will be about 10-12% higher than blood.

• Henry’s Law (deep lung air) states that in a closed system at a constant temperature and pressure there will be a fixed ratio between the concentration of a volatile substance in a liquied to that in the vapor phase above it.  Because Henry’s Law has as a component a pressure constant, changes in either atmospheric or barametric pressure can cause up to a 5% difference in the result.
• Partition Ratio – An underlying principle of breath testing is that the relationship between breath and blood alcohol is a constant ratio such that one volume of blood contains about the same amount of alcohol as 2100 volumes of alveolar air in normal healthy humans. This means that, in spite of a rather large concentration differences, alcohol excreted in the breath parallels that of the blood over the entire excretion phase (rising and falling).  This is the underlying principle for using breath to predict BAC.  This partition ratio has been the subject of extensive research, and has been shown to vary between 1900/1 (Dubowski) and 2692/1 (Wilkinson).

How Infrared “Sees” Alcohol in the Breath:

1.         Basic Chemistry of Ethanol:  The Beer-Lambert Law of Absorption provides the theoretical basis for IR breath testing. Molecules absorb electromagnetic radiation at certain specific, unique wavelengths. Thus, it may be said that each molecule has its own infrared fingerprint. Ethyl alcohol absorbs radiation at wavelengths of approximately 3.00, 3.39, 7.25, 9.18, 9.50 and 11.5 microns. Infrared instruments measure energy entering a vapor-filled cavity or sample chamber inside the instrument. When the IR energy beam emerges from the sample chamber, the instrument measures an energy loss in the affected IR wavelength regions if alcohol is present. The more alcohol the sample contains, the greater the degree of absorption and the more IR energy loss. 

2.         Light Source

3.         Sample Chamber

            a) Quartz Standard

            b) 3.44 micron “filter”

            c) 3.37micron “filter”

4.         Detector

            a) Chopper Motor (dc vs. ac current).

The Calibration and Maintainence of Evidential Breath Equipment:

1.         Factory Calibration

                        a)  Importance of the Use of Traceable Calibrators   

3.         Adminstrative Rules (field simulators)

The Test Run Sequence:

1.         Purging including Ambient Testing

2.         Ambient Zeroing

3.         Blank Test

4.         Internal Standard Test

5.         Sample (wet, dry, subject)

6.         Subject Sample