Darrin Flanigan and Jason Lusk

The ethanol concentration of three Kroger brand mouthwashes was determined by FTIR-HATR analysis. An ethanol-free mouthwash (Mouthwash C) was chose for analysis as well as a mouthwash with a nominal ethanol content of 25.9% (v/v) ethanol (Mouthwash A) and a mouth rinse with a nominal ethanol content of 17.4% (Mouthwash B). Data were acqu9red from the FTIR spectra by determining the peak height of th carbon-oxygen stretching band at 1045 cm-1 as well as the integrated area of the C-O band from 1118 to 999 cm-1. The peak height data showed mouthwash A containing 24.3 % ethanol and mouthwash B containing 19.2 % with percent errors of 6.1 % and 10.3 % , respectively, while eh peak area data showed Mouthwash A containing 29.7% ethanol and mouthwash B containing 19.8 % with percent errors of 14.7 % and 13.7 % , respectively. The detection limit of the procedure was determined to be 0.5 %. A large peak, caused by propylene glycol, appeared in the ethanol free mouthwash; this peak lies in the same region as ethanol and prevents an accurate measure of the ethanol content.