GC/FID analysis of ethanolic content in the gels. a Calibration curve for the quantification of ethanol. The calibration curve was prepared by analysing Carbopol® gels with a standard concentration (40–70% w/w) of ethanol. b The concentration of ethanol (% w/w) determined by GC/FID in the analysed hand sanitiser gels (1–7). The red line indicates the lower limit of the range of concentration of ethanol recommended by the WHO for hand sanitisers. “*” indicates products that are biocides