It has been known for many years that alcohol is an effective disinfectant; studies have shown that it is a better disinfectant when it is neither too weak nor too concentrated. Disinfectant efficacy is optimal at concentrations between 50% and 80%. Many institutions use 70% alcohol blends as standard.

Alcohol is suitable as a combined cleaning and disinfection agent provided no proteins are present, as alcohol will fix these to a surface by a process of protein denaturing. In this instance a separate cleaning agent should be used.

The alcohol can be diluted with either WFI, purified, or deionized water. Consideration should be given to whether the product contact area requires a disinfectant which is not only sterile but also free from endotoxins, in which case alcohol diluted with water for injection should be used.

The alcohol used can be either IPA or denatured ethanol. There is very little difference in efficacy between the two alcohols – the results are almost identical. The choice is reduced to other factors. IPA dries more readily but has a strong acrid smell and a lower occupational exposure limit than denatured ethanol. However, denatured ethanol has a sweeter smell that some users may find unpleasant.

Alcohol is almost exclusively used for transfer disinfection into isolators, as it is quick drying and leaves little or no residue. However, consideration should be given to the theoretical fire or explosion risk when spraying alcohol, as it is highly flammable and may need additional fans or ventilation to prevent the build up of vapour. The exposure limits should also be monitored when large quantities of alcohol are being sprayed: this can be simply checked by using chemical indicator tubes such as Draeger tubes. Both of these factors can be minimized by the use of sterile impregnated wipes. These are available in a range of presentations including sachets, tubs, or pouches.

From: “Cleaning of Isolators – A Vital Part of a Contamination Control Program”