Alcohol Test Methodology- What is a Breathalyzer?

Several different methods are available for alcohol testing. Alcohol test can be done via blood draw, breath, urine or saliva.

Blood Alcohol Testing

Blood Alcohol Concentration (BAC) is considered to be the standard for measuring the degree to which an individual is impaired by alcohol. For years, studies have shown that there is a direct correlation between the blood alcohol concentration and the degree to which reactions and judgments are impaired. The methodology used for blood alcohol testing is Gas Chromatography and is the most accurate forensic quality test in the industry today. However, drawing blood is an invasive and expensive procedure that most companies prefer to avoid.

It is well proven that there is a direct correlation between a person's blood alcohol concentration and his breath alcohol contents. During respiration, gas is exchanged from the lungs to the blood (primarily oxygen) during inhalation, and visa versa (primarily C02) during exhalation. During this exchange, alcohol in the blood vaporizes cross the lungs membrane into the exhaled breath. There are several types of breath alcohol testing devices available today. These range from disposable screening testers to the equipment that provides legally admissible test results, or devices ideal for screening purpose by companies as well as individuals . including very expensive digital read-out breath alcohol monitors. These types of testers fall into three categories:

The evidential breath testing devices are generally expensive (costs range from $3000-$5000 per unit), require regular maintenance, repair and calibration, and must be operated by Certified Personnel. Attachments such as sterile mouthpieces must be used each time a test is performed. These units are large table top units designed to be used in one location. Movement and environmental changes can effect the calibration parameters and settings which require recalibration and maintenance.

The portable hand held devices provide fairly accurate results and are used for screening purposes. By measuring the alcohol content in the breath, a reliable indication of the blood alcohol level is achieved. Portables devices are less accurate than evidential devices, however by comparing the cost performance ratio, these devices are affordable and sufficient for personal and corporate screening usage. Most potable devices are not evidential and not admissible in the court of law.

The disposable devices are noninvasive, and non scalable methods of screening for alcohol. Can be used to detect the presence of alcohol with an estimate to the degree of impairment. Being disposable, they are the most sanitary way of testing for alcohol. The disposable devices operate based on a known chemical reaction that is highly sensitive to alcohol and less sensitive to other gases. Unlike the semiconductor based sensors, the disposable devices are less likely to produce a false positive result. Being disposable makes these type of devices are the safest testers for the public and at much lesser cost than portable units.

Here's how the disposables work The ethyl alcohol in the blood escapes through the lung tissues into the exhaled breath. The presence of ethyl alcohol in the breath is detectable by a color change of very sensitive chemically coated media contained encapsulated in these Disposable devices. Immediately prior to use, the ampoule is ruptured by slight finger pressure on the outer flexible and clear tube to release the crystals within the confines of the ampoule. When the subject exhales into the tube, crystals interact with breath vapor and change color from yellow to White/green blue (aqua) if alcohol is present. If all the crystals change color completely from yellow to light blue or white to many eyes, it indicates that the subject's blood alcohol level is exceeding the tester's preset threshold level indicated on the tube.).02, .04, .05, or .08% BrAC.

Urine Alcohol Testing

Although urine alcohol testing will indicate the presence of alcohol in a person's body, it will not indicate an individual's current condition. Once consumed, alcohol enters the blood through the stomach wall within 15 minutes, causing immediate impairment. It is then metabolized by the liver enzyme and, after 1½ to 2 hours, it will begin to show up in the urine. Therefore, urine alcohol does not measure a true condition of the person. The results indicate the person's condition several hours before.

Additionally, urine alcohol concentration does not directly correspond to blood alcohol concentration. Urine alcohol concentration will vary depending on the person's metabolism and the amount of fluid in his system. For instance, a person who is slightly dehydrated will tend to have a higher alcohol concentration in his urine than someone who has a normal level of fluid in his system.

At least one study has indicated that a false positive for urine alcohol can occur. High levels of sugar and acetone in the body can cause fermentation in the urine, creating a false positive for urine alcohol. All things considered, the urine alcohol test is the least preferred or perhaps accurate test available for alcohol testing. It is worthwhile to read a supporting research paper published in THE AMERICAN JOURNAL OF CLINICAL PATHOLOGY: ERRORS OF CONVERTING A URINE ALCOHOL VALUE INTO A BLOOD ALCOHOL LEVEL. SIDNEY KAYE, PH.D., AND EDUARDO CARDONA, M. S.