Aminoxyl Catalyzed Electrochemical Ethanol Detection: Development of a New Breathalyzer Using Molecular Catalysis

Abstract

Blood alcohol concentration (BAC) is the indicator of alcohol intoxication, and its measurement has emerged as the most common analytical procedure requested by law enforcement. Due to its volatility, ethanol vapor can be detected in breath, and its vapor concentration is proportional to BAC. While portable breathalyzers have been designed for simple breath alcohol concentration detection, they are limited by high cost or the need for frequent recalibration. The first chapter of this thesis discusses the instrumentation used currently for alcohol detection, as well as the few recent attempts to improve the current methods of alcohol detection by adopting enzymatic detection methods. Although promising advancements have been made, the instability and high cost of enzymes prevent their commercial application.

Chapter three describes how the unique catalytic activity of the aminoxyl radical/oxoammonium redox couple toward alcohol oxidation was harnessed for fabrication of an electrochemical ethanol sensor for breath analysis with experimental details described in chapter two. Our functional sensing element consists of a screen-printed electrode in which the graphene oxide-based working electrode is modified with aminoxyl derivatives, of which 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl benzoate (TMB) was the most efficient derivative. Exposing this modified electrode to simulated breath that contains ethanol, while applying the required potential for oxidation of the aminoxyl radical, generates an electrocatalytic current proportional to the ethanol concentration in the breath. These simple, sensitive, durable, and inexpensive electrodes may contribute to the development of a single- use reliable ethanol sensor for personal or law enforcement applications.