Adjust Ingredient Volume
In the event where alcohol content of local active ingredient is lower than WHO formulation 2, we still can use the local ingredient and adjust the volume as per the formulas shown in previous section.
For instance, local active ingredient is 70% isopropyl alcohol in a 1 L bottle. As such, we won’t be able to achieve the same final product as per WHO formulation 2. However, we can still produce final product of isopropyl alcohol above 60% as recommended by CDC:
Isopropyl alcohol volume = 60 / 70 x 1000 = 857 ml
Hydrogen peroxide volume = 0.125 / 3 x 1000 = 41.7 ml
Glycerol volume = 1.45 / 100 x 10000 = 14.5 ml
Sterile distilled water volume = 1000 – (857 + 41.7 + 14.5) = 86.8 ml
It’s possible that a small amount of isopropyl alcohol may evaporate during the mixing process. Therefore, we may need to add more isopropyl alcohol to make up the loss.
Alternatively, we can increase the alcohol content in hand sanitizer. For example, we can produce hand sanitizer with 65% isopropyl alcohol instead:
Isopropyl alcohol volume = 65 / 70 x 1000 = 929 ml
Sterile distilled water volume = 1000 – (929 + 41.7 + 14.5) = 14.8 ml
Obviously, the lower the alcohol content of active ingredient, the more difficult to achieve target alcohol concentration in the final product. In this scenario, it’s advisable to produce larger volume of hand sanitizer like 5 L or 10 L so that the final ingredient volumes are not too small to manage.