Blood alcohol content

Ethanol is readily measured in the blood and reported as milligrams per milliliter (mg per ml) of blood. Laws regulating drinking and driving identify a specific blood alcohol concentration (BAC) as unacceptable when operating a motor vehicle. Currendy most states set 0.08 or 0.1, which is equivalent to 80 mg/100 ml or 80 mg/dl of blood. Alcohol content of exhaled breath is about 0.05% of the BAC. 

In one particular case, a motorcyclist hit a car and was severely injured. At the hospital, approximately one hour after the accident, the cyclist s blood alcohol content (BAG) was 0.021%. Back extrapolation (see Chapter 7) to the time of the accident could increase that value to 0.036%. His urine tests revealed use of cocaine and marijuana. Marijuana metabolites were confirmed by gas chromatography/mass spectrometry (GC/MS). All these results were used to try and prove that the cyclist was impaired. However, the presence of drug in urine is not a good indicator of drug concentration in blood or of impairment at the time of the accident, and the BAG was probably too low to cause impairment. At best, one could say that the cyclist does use drugs and uses several of them at the same time, but use of the drugs may not have played a role in causing the accident. The case was settled. 

The color of the solution changes because some of the orange Cr2072- is converted to the green Cr3+. The Breathalyzer measures the color change and produces a meter reading calibrated in terms of blood alcohol content. 

Oxidation-Reduction in Blood Analysis Demonstrating the Reaction in a Breathalyzer," J. Chem. Educ., Vol. 67,1990, 263. The oxidation of a primary alcohol by the orange dichromate ion is shown to first form an aldehyde, then a carboxylic acid, and green chromium(III) ion. The use of this reaction, principles of spectrometry, and gas laws in a commercial device for measuring blood-alcohol content are discussed. 

A more down-to-Earth use of fuel cells is found in traffic-law enforcement. Police officers need quick and simple ways to determine a person s blood alcohol level in the field. In the time it takes to bring a person to the station or to a hospital for a blood or urine test, the person s blood alcohol content (BAG) might change. Fuel cells, such as the one in the device shown above, provide a quick and accurate way to measure BAG from a breath sample. The alcohol ethanol from the person s breath is oxidized to acetic acid at the anode. At the cathode, gaseous oxygen is reduced and combined with hydronium ions (released from the anode) to form water. The reactions generate an electric current. The size of this current is related to the BAG. 

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. 

The blood alcohol content of an individual is determined enzymatically by reacting ethanol with NAD" in the presence of the enzyme alcohol dehydrogenase to produce NADH (Table 22.1). The rate of formation of NADH is measured at 340 nm (Figure 22.4). The following absorbances are recorded for a 0.100% (wt/vol) alcohol standard and the unknown, treated in the same way. Use a spreadsheet to calculate the rates of absorbance changes and from these, the unknown concentration. 

Additionally, bars and restaurants that serve alcohol should have breathalyzers for customers to use before they leave the premises. Customers with blood alcohol content of 0.08 or above should be assisted with transportation. If a customer with a high blood alcohol content refused alternative transportation, the business should be required to notify the police or face a suspension of their liquor license. Customers who are clearly inebriated and refuse to take a breathalyzer should also be reported. 

Estimation of Blood Alcohol Content with Bioimpedance Spectroscopy... 

M.Ulbrich, M. Czaplik, A. Pohl, etal, Estimation of Blood Alcohol Content with Bioimpedance... 

Alcohol and risk of crash involvement Drivers with high BAG (Blood Alcohol Content) in their blood have more chance of being killed than those with zero BAG (sober drivers). Hakkert Braimaister (2002) provided a review of many studies and reported that the risk in traffic will increase rapidly with BAG. Such results have given the basis for setting BAG limits in many countries (e.g.. 08 g/dl). Thoresen et al. (1992) have shown a positive correlation between the total number of fatalities in Victoria state in Australia with alcohol sales and inverse relationship with random BAG breath testing. 

X Reporting for duty with a blood-alcohol content (BAG) of 0.04 or greater ... 

A driver being tested for blood alcohol content with a handheld breathalyzer. 

The driver of the pickup tmck had a blood alcohol content (BAG) of 0.24, more that 1 Vi times the legal limit at the time. A court convicted him of manslaughter and sentenced him to 17 years in prison. 

Potassium dichromate oxidation of ethanol to acetic acid is the basis for the original breath alcohol screening test used by law enforcement agencies to determine a person s blood alcohol content. The test is based on the difference in color between the dichromate ion (reddish orange) in the reagent and the chromium(lll) ion (green) in the product. Thus, color change can be used as a measure of the quantity of ethanol present in a breath sample ... 

Both tests measure alcohol in the breath.The legal definition of being under the influence of alcohol is based on blood alcohol content, not breath alcohol content. The chemical correlation between these two measurements is that air deep within the lungs is in equilibrium with blood passing through the pulmonary arteries, and an equilibrium is established between blood alcohol and breath alcohol. It has been determined by tests in persons drinking alcohol that 2100 mL of breath contains the same amount of ethanol as 1.00 mL of blood. 

Figure 1.12 Depiction of perspiration detection of blood-alcohol content (BAC) through the electrochemical detection of the alcohol oxidase.

Many police departments use breath tests to check for drunk drivers. What would be the approximate partial pressure of ethanol in expired breath if the blood alcohol content is approximately 0.06 mole % (that is, Xe,hanoi = 0.0006) The equilibrium vapor pressure of C2H5OH at 37°C is 115.5 torr. Use your answer to comment on the necessary sensitivity of the test. 

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