Comparison of Blood Ethanol Concentrations in Samples Simultaneously Collected into Expired and Unexpired Venipuncture Tubes

Abstract

Blood sample collection kits manufactured for the Minnesota Bureau of Criminal Apprehension contain venipuncture tubes with an expiration date that the tube manufacturer utilizes to ensure sufficient vacuum to fill the tubes. Legal challenges to blood ethanol analyses that involved the use of expired venipuncture tubes prompted a study comparing ethanol analysis results in expired venipuncture tubes (up to 74 months beyond the expiration date) and in unexpired venipuncture tubes. Blood samples were collected during controlled drinking sessions using 10-mL venipuncture tubes containing 100 mg of sodium fluoride and 20 mg of potassium oxalate and were analyzed by headspace gas chromatography. The data obtained indicate that the ethanol concentrations in the expired and unexpired venipuncture tubes were statistically identical.