1. Understanding Alcohol Detection

2. Determining BrAC (Breath Alcohol Concentration)
When alcohol is consumed it is absorbed into the blood stream.
The exchange of alcohol to the breath occurs in the deep lung region.
Through a calculated conversion, the SL2 measures alcohol in the body by its concentration in breath, also known at breath alcohol concentration (BrAC). 
There is a direct relationship with the concentration of alcohol in the blood and in the breath.

3. Alcohol Effects on the Body
Some factors that determine a person’s BrAC:
Number of drinks and alcohol content
Amount of time in which drinks are consumed
Level of alcohol tolerance
Body weight
Gender and age
Food intake
Example of 160 lb male – approximate BrAC:
2 drinks in 1 hr = approx .03 BrAC
4 drinks in 3 hr = approx .05 BrAC
Example of 120 lb women – approximate BrAC:
2 drinks in 1 hr = approx .06 BrAC
4 drinks in 3 hr = approx .10 BrAC

4. Rate of Elimination of Alcohol
How quickly does alcohol leave the system (elimination rate)?
Studies show elimination rate can vary dramatically from person to person
Even the same person can have varying absorption rates from day to day
Dr. Alan Wayne Jones (top forensic alcohol toxicologist & researcher)
found people fall in one of the below groups.
Group Type Expected Rate of Elimination (per hr.)
Slow elimination rate
Moderate elimination rate
Rapid elimination rate
Ultra-Rapid elimination rate
(Source; James G. Wigmore, Rate of Elimination of Alcohol – An Evidence-Based Review)

5. SL2 Fuel Cell Manufacturer – DART Sensors
Dart is the world's largest supplier of alcohol fuel cell sensors and sensor components.
The number one choice for manufacturers who do not make their own sensors.
35 years of experience developing fuel cell technology.
Meets approval standards at all levels including police use, interlock, and consumer products in many countries including USA, UK, France, Sweden, and Australia.
Detection Range: % BrAC
Accuracy: +/ BrAC
1,500 tests
Technology separation: Using double coating, and patented biporous components, the geometry of the sensor electrodes is fixed, and the electrolyte variations are largely confined to the reservoir wafer, an uncoated component, which gives good batch consistency and long term calibration stability.

6. Breathalyzer 101: Measuring BrAC
When a breath sample containing alcohol is in contact with the surface of the fuel cell, the alcohol is quickly absorbed by the fuel cell. A chemical reaction occurs in the fuel cell, in which the alcohol oxidizes.
This oxidation converts alcohol to acetic acid and releases an electrical current.
The more alcohol present in the sample, the greater the chemical reaction and the higher the BrAC.
If there is no alcohol present in the sample there is no chemical reaction, no electrons release, result would be .00

7. Fuel Cell FAQ’s What is the lifetime of the Dart fuel cell sensor?
Five years is typical. You cannot really over-use them, in fact they seem to last longer when well-used than when hardly used at all.
How often is calibration needed?
Calibration checks are often carried out at 6 months or yearly intervals. A device may not need to be recalibrated for many years, but periodic accuracy checks are still important. SOBERLINK recommends recalibration at 1,500 tests.
What is the lowest alcohol detection limit with the Dart fuel cell sensor?
Under practical conditions the sensor has no difficulty reading down to BAC
Are the sensors sensitive to substances other than ethanol?
There is no sensitivity to the following substances: acetone and other ketones; toluene, benzene and other aromatic hydrocarbons; ethyl acetate and similar esters; methane, ethane and other saturated hydrocarbons; carbon dioxide; water vapor.
There is sensitivity to the following substances: methyl alcohol (i.e. paint thinner), isopropanol (i.e. aftershave), carbon monoxide, diethyl ether. Waiting minutes after exposure to these agents should result in a compliant test. 7

8. False Positives
A false positive will show as a initial violation, but second test will be .00
Contacts will receive automated alert on both the positive test and the compliant second test if it’s false positive (i.e. mouthwash)

9. Effects of Mouthwash

10. Avoiding False Positives
Honor deprivation periods – clients who honor the 20 minute deprivation period
before testing should have no issues with a false positive that could be a result of
using mouthwash or other alcohol based products.
Establish rules with the client – if there is a positive test, make sure the client knows they
are to retest and failure to do so, could be deemed a violation. Note, the client will
be warned by the device and a text message to retest, but it should still be understood
in advance.
Client Agreement Form – Having the client sign a participant agreement form will
help reduce issues later. Have the client initial or sign off on all the Do’s and Don’ts
of testing so there are no surprises (Soberlink can provide sample agreements for review).

11. What a drinking event looks like…
On a non-compliant test (.02 or higher), client receives a retest warning on the device and a text message on their mobile phone to submit a secondary test (i.e. confirmation test).
If secondary test is non-compliant, user will be asked to retest every 30 minutes until compliant.

12. Glossary of Common Terms
Mouth Alcohol – The most common cause of false breathalyzer readings is the existence of mouth alcohol. The breathalyzer functions under the assumption that the alcohol in the breath came from deep within the lungs. However, alcohol may have come from the mouth, throat, or stomach for a number of reasons. To guard against mouth alcohol contamination, the subject should wait minutes after eating or drinking anything before testing.
Secondary Test (or confirmation test) – After a non-compliant test, the user will be asked to submit a secondary test to confirm the presence of alcohol in the system. An alcohol-based item, like mouthwash, will dissipate in 15 minutes and should not continue to show a positive result.
Compliant Secondary Test – The first compliant test result that follows a positive test and is within the secondary test window.
Retest Cycle – After a positive secondary test, the user will be prompted to retest every 30 minutes until the test is compliant (or 3 hours elapses).