10.5 Notes Analysis of blood

Objectives ► List and contrast laboratory procedures for measuring the concentration of alcohol in the blood. ► Relate the precautions to be taken to properly preserve blood in order to analyze its alcohol content. ► Understand the signification of implied-consent laws and the Schmerber v California case to traffic enforcement.

Analysis of Blood for Alcohol ► Gas chromatography  Most widely used approach for determining alcohol levels in the blood  Separates alcohol from other volatile substance in the blood  High degree of accuracy  Used in most forensic labs

Another approach ► Spectrophotometer  measures conversion of alcohol to acetaldehyde in the oxidation process that is mediated by a coenzyme NAD to NADH  Nicotin-amide-adenine-dinucleotide  The NADH is measured and is related to alcohol consumption  Used in hospital settings

Blood Collection and Preservation ► Drawn by qualified individual ► Procedure must be sterile with nonalcoholic disinfectants  Negates any argument about false reading ► Sealed in airtight container with an anticoagulant (EDTA or potassium oxalate) and preservative (sodium fluoride) ► Stored in refrigerator

► Anticoagulant prevents blood from clotting ► Preservative inhibits microorganisms from destroying the alcohol ► Signification factors to consider:  Storage temperature  Presence of preservative  Time of storage

Postmortem ► Ethyl alcohol can be generated as a result of bacterial production ► Samples collection from several body sites  heart, femoral vein and cubital vein  Also, vitreous humor fluids and urine should also be collected because they don’t suffer from ethyl alcohol production

Alcohol and the Law ► States have uniform blood alcohol standards using the AMA and NSC recommendation ► 1992, Department of Transportation recommended 0.08 as legal measure  Became federal law in 2000  States that don’t follow lose transportation funding  Commercial drivers = 0.04 legal limit

Alcohol and the Law ► Other countries have similar or standards less than.08 ► 1973 – Implied consent law – submit to the test or lose your license for 6 mo. to 1 yr.  Prevents a person’s refusal to take a test for intoxication on the constitutional grounds of self-incrimination  Standard is Schmerber v. California

10.5 Questions What analytical technique is the most widely used approach for determining alcohol levels in blood? What type of disinfectant must be applied to a subject’s skin before drawing blood? Why must such a disinfectant be applied? What type of container best ensures the preservation of blood samples? What two substances should be added to a blood sample after collection and why? How does each of the following factors affect alcohol’s stability in blood: storage temperature, the presence of a preservative, and the time of storage? When collecting postmortem blood samples for alcohol determination, why is it best to collect a number of blood samples from different body sites? What blood-alcohol concentration is the current legal measure of drunk driving in the US as established by the National Highway Traffic Safety Administration? What is an implied consent law? Why were such laws implemented?