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Blood Testing Methods in Florida

Rule 11D-8.002(14) defines the term ”blood" to mean "whole blood." The term ”whole blood" is defined as the blood as it flows from the body and contains all of its constituents—white blood cells, red blood cells, platelets, and all of the unformed elements that are dissolved in the blood plasma.

The elements that are dissolved in the blood plasma would include proteins and enzymes. Under Florida's implied consent laws, only whole blood may be tested for blood alcohol analysis.


Methods of Blood Testing in Rule 11D-8.011

Prior to July 29, 2015, Rule 11D-8.011 approves the following two methods of blood alcohol testing:

  • the alcohol dehydrogenase (enzymatic) method; and
  • the gas chromatography method.

All forensic laboratories in Florida that test blood under the implied consent laws currently use the gas chromatography method. Although the enzymatic method was used for forensic blood alcohol testing in Florida in the past, it is not used at this time.

Rule 11D-8.011 was amended on July 29, 2015, to remove alcohol dehydrogenase (enzymatic) method as an approved method of blood alcohol testing.


Headspace Gas Chromatography Method of Blood Testing

The headspace gas chromatography method measures the alcohol in the gas above the blood sample, which is called the "headspace gas.” Under the headspace gas chromatography method of testing a blood sample, a sub-sample of blood is drawn from the collection tube and mixed with an "internal standard.”

The internal standard is a liquid that dilutes the blood and makes the blood alcohol results quantifiable.

Rule 11D-8.013 requires analysts testing blood with the gas chromatography method to use an internal standard technique, but does not specify the dilution ratio.

After the internal standard is added to the sub-sample, the blood is heated and pressurized, causing the alcohol in the blood sample to equilibrate into the headspace above the sample. A sample of the headspace gas (which contains the vaporized alcohol) is pushed into a column in a machine called a gas chromatograph.

The gas interacts with a coating on the inside walls of the column, causing the individual components of the gas to separate. A detector is then used to measure the components and determine the amount of alcohol in the sample.


Enzymatic Method of Blood Alcohol Concentration Testing

The enzymatic method uses an enzyme called alcohol dehydrogenase to drive a reaction in the blood that converts ethanol to acetaldehyde. Ethanol is the alcohol contained in alcoholic beverages.

A color dye is added during the reaction that creates a color change in the blood. The blood analyst measures the amount of alcohol in the blood by shining a specific wave length of light through the blood (after the reaction) and measuring the absorbents.

The amount of absorbents is directly proportional to the amount of alcohol in the sample. The result of blood alcohol testing using the enzymatic method depends on the color of the blood sample.

Rule HD-8.013(3)(g) requires that enzymatic testing be performed according to the procedure recommended by the manufacturer/test kit vendor for whole blood analysis.


Finding an Attorney for DUI Blood Test Cases in Tampa, FL

If your DUI cases involves a blood test using headspace gas chromatography, then contact an experienced DUI defense attorney in Tampa, FL. Call us for a free consultation to discuss your case.

Find out more about the charges pending against you, the method used to test your blood after a DUI arrest, and defenses that might apply to your case. Call 813-250-0500.


This article was last updated on Friday, March 3, 2017.