Alcohol-Based Hand Sanitizers: Relevance of the Physicochemical Properties of Alcohol-Water Mixtures

Nasser N Nyamweya; Kennedy O Abuga

Nasser N Nyamweya Pharma Manufacturing Solutions, P.O. Box 21297 - 00505, Nairobi, Kenya
Kennedy O Abuga Department of Pharmaceutical Chemistry, Pharmaceutics & Pharmacognosy, Faculty of Health Sciences, University of Nairobi, P.O. Box 19676 - 00202, Nairobi, Kenya

Keywords: Alcohol-water mixtures, polarity, viscosity, vapor pressure, surface tension, disinfection, hand sanitizers

Abstract

The use of alcohol-water mixtures as antimicrobial agents for hand-hygiene grew significantly in the year 2020 due to the global COVID-19 pandemic. Combining alcohols, such as ethanol or isopropanol, with water results in mixtures with a number of unusual characteristics with several solution properties deviating from ideal behavior. These characteristics are related to clustering or aggregation of the constituent molecules at the microscopic level. This paper reviews the physicochemical properties (polarity, density, viscosity, vapor pressure, surface tension) of alcohol-water mixtures and their relevance to alcohol-based hand sanitizers. The role of the quasi-surfactant characteristics (amphiphilism, surface and interfacial tension lowering) of alcohols in eliciting their antimicrobial effects is discussed.