Breath alcohol analyzer

Several commercial evidential breath alcohol measurement devices are available. The principle of measurement is either infrared absorption spectrometry (most common), dichromate-sulfuric acid oxidation-reduction (photometric), GC (flame ionization or thermal conductivity detection), electrochemical oxidation (fuel cell), or metal-oxide semiconductor sensors. A list has been published of DOT-approved breath alcohol devices.Some of these devices are approved for screening only. In this case, the second or confirmatory breath alcohol determination must be performed with an approved evidential breath alcohol analyzer. Breath alcohol devices may also be used for the medical evaluation of patients at the point of care (e.g., emergency department). A Fourier transform infrared point-of-care breath analyzer capable of measurement of... 

Similar techniques are used to measure alcohol in blood, serum, saliva, or urine and for postmortem specimens (e.g. vitreous fluid and skeletal muscle). Determination of ethanol in expired air requires specialized breath alcohol analyzers (see section on Breath Alcohol). 

Features. A series of boxed and highlighted Features are found throughout the text. These essays contain interesting applications of analytical chemistry to the modern world, derivation of equations, explanations of more difficult theoretical points, or historical notes. Examples include Breath Alcohol Analyzers (Chapter 7), Antioxidants (Chapter 20), Fourier Transform Spectroscopy (Chapter 25), LC/MS and LC/MS/MS (Chapter 32), and Capillary Electrophoresis in DNA Sequencing (Chapter 33). 

Schematic diagram af a breath analyzer. The alcohol in the driver s breath is reacted with a potassium dichromate solution. The change in the absorption of light Meter registered by the de-...

When a driver is arrested for suspicion of driving under the influence of alcohol, the blood alcohol content is determined to see if it exceeds the legal limit. The measurement of breath alcohol is usually done for routine driving arrests because it is noninvasive, and a factor is applied to convert to blood alcohol concentration (BAG). But this is subject to biological variations in individuals. In cases where there is an accident, injury, or death, the blood alcohol is usually determined directly, by analyzing a blood sample by gas chromatography. 

Razatos, G., Luthi, R. and Kerrigan, S. (2005) Evaluation of aportable evidential breath alcohol analyzer. Forens Sci Int, 153 (1), 17-21. 

One interesting example of infrared analysis is an infrared gas analyzer used to determine breath-alcohol levels of motorists [7]. 

Concerning the clinical trial, significant changes for all examined values were analyzed with a focus on measurement point 0 and 3. The extracellular resistance showed the best performance. Figure 6 presents the calculated R and measured breath alcohol concentration over the measurement period for one representative subject. 

The well-established GC methods for blood ethanol determination are today the Gold Standard in cases, where, for instance, results from the quantitative breath-alcohol analyzer used for evidential purpose are challenged. The basis for this importance is an overwhelming amount of data available from the GC tests and the rigorous QC scheme for precision and accuracy testing. 

One of the worries about many previous investigations of the effects of solvent abuse has been that, because objective measures to detect current intoxication have rarely been included, it has not been possible to reject the hypothesis that the cases were intoxicated, or at least still subject to the acute effects of solvents, at the time the psychological tests were administered. In order to ensure that the present study was concerned with the long-term effects of solvent abuse rather than the immediate effects of intoxication, it was necessary to be able to detect and, if necessary, exclude those children who were under the acute influence of solvents (or alcohol) at the time of testing. This was done by analyzing breath samples om each child... 

As a matter of procedure tihe measurement of drivers BAG is most often not based on direct measurement of the blood content. Instead drivers are asked to blow into a portable breath tester and their lung air is analyzed. Because the breath alcohol concentration is proportional to the BAG by a factor of 2.2727 (Vanlaar, 2005), the breath alcohol content can be easily converted into blood alcohol concentration. For example, a breath alcohol concentration of 0.22 mg alcohol per liter of exhaled air is equivalent to 0.5 g/1 in the blood, or 0.05% BAG. 

A final example of an application of balanced chemical equation involves the use of one form of the breath analyzer used by police to determine if someone was driving under the influence of alcohol. The chemical equation guiding the reaction when someone breaths into the instrument is... 

The equation shows that alcohol in the form of ethanol reacts with an orange solution of potassium dichromate to produce a green solution of chromic sulfate. The source of alcohol is the suspect s breath. More alcohol produces a greater color change. The breath analyzer measures this color change and coverts this measurement into an amount of alcohol in the blood. 

Alcohol determinations at the roadside or at home are typically done with a breath analyzer or breathalyzer. Because of rapid gas exchange and the vapor pressure of ethanol, the concentration exhaled is directly related to the blood alcohol concentration. The blood alcohol concentration is widely used as a criterion for determining whether a person is under the influence of alcohol. Many states have ruled that a blood alcohol level of 0.1% or greater indicates intoxication. 

The alcohol in beverages, hair spray, and mouthwashes is ethanol. Ethanol is a volatile liquid that evaporates rapidly at room temperature. Because of this volatility, drinking an alcoholic beverage results in a level of gaseous ethanol in the breath that is proportional to the level of alcohol in the bloodstream. About 50 percent of all automobile accidents that result in a fatality are caused by intoxicated drivers. Law officers can determine quickly whether a person is legally intoxicated by using an instrument called a breath analyzer, or Breathalyzer. 

The police often use a device called a breath analyzer to test drivers suspected of being drunk. The chemical basis of this device is a redox reaction. A sample of the driver s breath is drawn into the breath analyzer, where it is treated with an acidic solution of potassium dichromate. The alcohol (ethanol) in the breath is converted to acetic acid as shown in the following equation ... 

You analyze a breathalyzer test in which 4.2 mg K2Cr207 was reduced. Assuming the volume of the breath was 0.500 L at 30.°C and 750. mm Hg, what was the mole percent alcohol of the breath ... 

Figure 18.14 is a spectrum of a dog s expired air three hours after the forced ingestion of isopropyl alcohol. The alcohol bands and those of its metabolite, acetone, can be specifically and quantitatively identified. Ethyl alcohol can be specifically and quantitatively analyzed in human breath and such infrared analysis permits one to estimate blood alcohol concentration. 

Finally, GC can be used to determine alcohol concentration in breath specimens obtained from living subjects. Appropriately modified GCs are used, and directly collected or field-collected breath can be analyzed. These chromatographs are equipped with an appropriate multisampling valve for injecting the sample and a flame ionization detector (FID). ... 

A New Blood Alcohol Breath Analyzer with Piezoelectric Detector. II. Effect of Composition on n-Octa-decanol Solvolysis of Zinc Stearate by Gas Chromatography Univ. Microfilms Int., Order No. 77-17,392, 221 pp. Diss. Abstr. Int. 38B(2) 629 (1977) CA 87 162299c... 

The practice of breath collection onto silica adsorbent for later analysis to compare to the results of an evidential breath-testing device (EBT) is currently being performed in some laboratories in the United States. The contents are emptied into a vial, diluted with an aqueous internal standard solution (n-propanol) and analyzed by headspace GC using procedures similar to those for blood alcohol analysis, but adjusted for sensitivity differences. Reanalysis of breath samples collected in this manner is not recommended, however, due to factors other than instrument performance, such as sample collection and operator errors. 

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