Abstract
Accurate determination of the concentration of alcohols and their metabolites is important in forensics and in several life science areas. A new headspace gas chromatography-mass spectrometry method has been developed to quantify alcohols and their oxidative products using isotope-labeled internal standards. The limit of detection (LOD) of the analytes in the developed method was 0.211 µg/mL for methanol, 0.158 µg/mL for ethanol, 0.157 µg/mL for isopropanol, 0.010 µg/mL for n-propanol, 0.157 µg/mL for acetone, and 0.209 µg/mL for acetaldehyde. The precision and accuracy of the method were evaluated, and the relative standard deviation percentages were found to be less than 3%. This work demonstrates the application of this method, specifically in quantifying the concentration of oxidative products of alcohol and other minor alcohols found in hand sanitizers, which have become an essential household item since the COVID-19 pandemic. Apart from the major components, the minor alcohols found in hand sanitizers include methanol, isopropanol, and n-propanol. The concentration range of these minor alcohols found in ethanol-based hand sanitizer samples was as follows: methanol, 0.000921-0.0151 mg/mL; isopropanol, 0.454-13.8 mg/mL; and n-propanol, 0.00474-0.152 mg/mL. In ethanol-based hand sanitizers, a significant amount of acetaldehyde (0.00623-0.231 mg/mL) was observed as an oxidation product, while in the isopropanol-based hand sanitizer, acetone (0.697 mg/mL) was observed as an oxidation product. The concentration of acetaldehyde in ethanol-based hand sanitizers significantly increased with storage time and temperature, whereas no such increase in acetone concentration was observed in isopropanol-based hand sanitizers with storage time and temperature. In two of the selected hand sanitizers, the acetaldehyde levels increased by almost 200% within a week when stored at room temperature. Additionally, exposing the hand sanitizers to a temperature of 45 °C for 24 h resulted in a 100% increase in acetaldehyde concentration. On the contrary, the acetone level remained constant upon the change in storage time and temperature.