Alcohol Depletion in Simulator Solutions used with the Intoxilyzek® 5000C System Calibration Check

Abstract

ABSTRACTUsing alcohol-water solutions in wet bath simulators for calibration verification of breath alcohol testing instruments is a commonly employed safeguard in breath test programs. The forensic value of this practice is critically dependent on the simulator solution maintaining a correct alcohol concentration over the time it is applied for this purpose. Alcohol depletion is a recognized phenomenon with simulator solution use. The purpose of this study was to evaluate the extent of alcohol depletion occurring in simulator solutions used in performing repeated calibration checking of an Intoxilyzer® 5000C instrument operated in recirculation mode. Measurements of alcohol depletion were made on simulator solutions used in trials involving 50 to 100 calibration checks performed over periods of 14 to 33 days. In three of the four trials, alcohol depletion was found to be significant at the 99% Confidence Interval (CI) with solution concentrations decreasing more than 3 percent from the original target values. The use of recirculation for calibration checks of the Intoxilyzer® 5000C provides a conserving effect on the amount of alcohol lost from the solution. However, the results of this study suggest that even with recirculation, significant decreases in alcohol concentration occur when repeated tests are performed over time with the same solution. Where recirculation is used, alcohol depletion appears to remain a factor that should be monitored as one part of maintaining the overall quality assurance in a breath alcohol program.