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The Accuracy of Blood Alcohol Test Kits

written by: Cyndi Root•edited by: Emma Lloyd•updated: 6/18/2010

Blood alcohol test kits are common because of their portability and simplicity, however more precise measurements can be found using a blood sample and the gas chromatograph and the spectrometer.

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    Emergency room doctors do not rely on the accuracy of blood alcohol test kits. Medical professionals must accurately diagnose and treat patients. Medical procedures that are ordered may depend on accuracy and doctors agree that breath or saliva test kits used in the field by say, law enforcement, are not accurate enough. Tests by scientists have shown that breath tests from a kit measuring for blood alcohol content were at least .10 less than serum alcohol concentrations. Legal proceedings as well, may depend on the accuracy of tests.

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    Kits are Useful in the Field

    While breath analyzers kits are .10 mg/dl less accurate, they are useful for their portability, simplicity of use, affordability, and do not requirement machine maintenance. Saliva tests are also used frequently. The test strip is dipped in saliva or urine and when the color changes the tester simply compares the color to a reference chart to determine the blood alcohol content. Saliva testing is preferred over breath testing methods for accuracy.

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    Kits Can Be the First Line of Detection

    While serum alcohol concentrations test are the most accurate and have a high degree of reliability, their high level of intrusiveness and high costs, make these tests the least likely to be used. Since many workplaces accidents are the result of alcohol ingestion, employers are instituting alcohol tests for the first time and more often. Employers are searching for reliable and cost effective means for testing blood alcohol content. The accuracy of blood alcohol test kits vary, however these kits may be used as the first line of detection. If alcohol is found, employers or law enforcement may elect to proceed to testing using serum alcohol concentration.

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    Spectrometer is Useful but Has Drawbacks

    Another serum alcohol measurement is with an enzymatic assay. A spectrometer measures alcohol which was converted into a form the spectrometer can read. Drawbacks to this method are mainly in law enforcement, which requires the use of whole blood which this test does not use. However, this enzymatic test is accurate and precise.

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    Chromatograph is Best

    Doctors feel that the best test for blood alcohol is serum alcohol testing with gas chromatography. One way is to insert the blood sample which has been diluted with an aqueous solution into the chromatograph to be measured. Another way is called headspace vapor sampling and is accomplished by injecting the aqueously diluted blood sample into the gaseous phase of the chromatograph. Physicians often prefer the simple method over the vapor sampling methods because it takes less time. The vapor sampling process does take more time and is more complicated, but can detect alcohol as low as 10 milligrams per deciliter.