Coronavirus: How to Make Alcohol Hand Sanitizer with WHO Recipe

Effective alcohol hand sanitizer with WHO recipe

Since the outbreak of coronavirus disease COVID-19 pandemic, there’s a constant shortage of hand sanitizers and face masks in local supermarkets and pharmacies. Meanwhile, it’s frustrating to find them in e-commerce stores selling at inflated prices. Instead of living at their mercy, we should make hand sanitizer ourselves while working from home.

There’re many homemade hand sanitizer recipes available in Internet but not all are effective in killing virus. Therefore, we shall refer to a respected health authority like WHO where the recipes are also endorsed by FDA.

Requirements for Effective Alcohol Hand Sanitizer

To make effective hand sanitizer, we need to understand facts about active ingredients:

1. According to CDC, hand sanitizers should contain 60-95% of alcohol as active ingredient to be effective in killing germs. Concentrated alcohol is effective in destroying the envelope protein of coronavirus.
2. We can ignore all hand sanitizer recipes that use lower than 70% alcohol as active ingredient. With low alcohol content, it can be quite challenging to achieve final concentration above 60% in small production.
3. Common alcohol concentration of vodka is 40% which means vodka is an ineffective active ingredient. Unless you manage to get hold of vodka with 80-90% of alcohol.
4. FDA has issued a final rule on the eligible active ingredients for over-the-counter hand sanitizers:
   1. Alcohol 60-95%
   2. Isopropyl alcohol 70-91.3%
   3. Benzalkonium chloride (non-alcohol, not in WHO recommendations)
5. Frequent use of pure alcohol causes skin dryness, irritation and inflammation. To preserve skin moisture, it’s therefore important to add humectant or emollient in hand sanitizer. Examples of natural humectants are glycerin and aloe vera gel. Popular emollients are plant oils like sweet almond oil and olive oil.

Even if we can’t find the exact alcohol contents locally as per WHO recipes, we can adjust the volume as explained here. But first, let’s look at WHO recipes.

WHO Recipes for Alcohol Hand Sanitizer

WHO has recommended the following 2 recipes for local production of hand sanitizers.

Raw Ingredient Preparation Before Mixing

Note:

1. Ethanol and isopropyl alcohol are active ingredients for killing virus.
2. It’s advisable buy active ingredients locally due to high import duty for alcohol, and legal requirements by local authority.
3. Hydrogen peroxide is acting as a disinfectant for the mixed solution so that the solution is free from bacterial spores.
4. Glycerol is a humectant for moisturizing the skin.
5. If the concentrations or volumes of local ingredients are different, refer to this article for adjustment.

Final Product of Alcohol Hand Sanitizers After Mixing

Note:

1. The total volume of final product is 10 000 ml or 10 L.
2. “v/v” stands for “volume per volume” which is a measurement of solution concentration.
3. Active ingredient of 80% (v/v) means for every 100 ml of mixed solution, there’s 80 ml of active ingredient.
4. A study suggests that reducing glycerol from 1.45% to 0.725% can improve the effectiveness of active ingredients.

Containers and Apparatus for Local Production

WHO formaulations are designed for local production of 10 L of alcohol hand sanitizers. For production of different volume, adjust the sizes of the container and bottles accordingly.

Mixing container (choose one only):

1. 10 L glass or translucent plastic bottle with screw-threaded stopper, or
2. 50 L translucent plastic tank with drainer, or
3. 80-100 L stainless steel tank with lid

Apparatus:

1. Wooden, plastic or metal paddle
2. Measuring cylinders and jugs
3. Plastic or metal funnel

Quality control:

1. Alcohol meter

Portable storage bottles :

1. 100 ml plastic bottles with leak-proof tops (100 bottles for 10 L of final product)
2. 500 ml glass or plastic bottles with screw tops (20 bottles for 10 L of final product)

Step-by-Step Procedures to Produce Alcohol Hand Sanitizer

Depending on the active ingredient available locally, prepare the ingredients according to either WHO formulation 1 or 2. The preparation steps are:

1. Pour the active ingredient (either 8333 ml of ethanol or 7515 ml of isopropyl alcohol) into the selected mixing bottle/tank.
2. Use measuring cylinder to add 417 ml of hydrogen peroxide into the mixing bottle/tank.
3. Use measuring cylinder to add 145 ml of glycerol into the mixing bottle/tank. Note that glycerol will stick to the inner wall of the cylinder. So rinse it with sterile distilled or boiled cold water and pour the water into the mixing bottle/tank.
4. Fill the mixing bottle/tank with sterile distilled or boiled cold water to 10 L mark.
5. Tighten the screw-threaded stopper or cover with lid (whichever applicable) immediately to minimize evaporation.
6. Shake the bottle/tank gently to mix the solution. Or use a paddle to mix the solution if the tank has no stopper.
7. Divide the mixed solution in the portable storage bottles immediately and quarantine them for 72 hours. During this period, hydrogen peroxide kill bacteria spores in the mixed solution and bottle if any.

Professional demonstration on alcohol hand sanitizer production.

Quality Control

It may be necessary to verify the alcohol concentration before and after the productions:

1. Pre-production analysis (before mixing). Use alcohol meter to verify that the alcohol concentration is same as the label. If not, it’s necessary to adjust the alcohol volume accordingly. The step is necessary to ensure that the alcohol content in final product is accurate.
2. Post-production analysis (after mixing). Use alcohol meter to verify that the alcohol concentration in the final product falls within ±5% of the target concentration. If the target concentration falls below 5% due to evaporation, add small amount of alcohol in the final product. Repeat this step until the alcohol content falls within ±5% of the target concentration. This step is important for small volume production because the error margin of alcohol content is bigger.

Safety Precautions

Since alcohol is highly flammable, please follow the safety guidelines faithfully as recommended by WHO:

1. Buy from local suppliers with appropriate storage and transport licenses as required by local authority.
2. Refer to local authority for the maximum storage limit before a storage license is required by law.
3. Keep in cool and well-ventilated area like air-conditioned room. Do no expose to sunlight.
4. Store far away from flame and heat like kitchen or heater.
5. Most importantly, keep out of reach of children!

The Most Effective Solution for Hand Hygiene

Even with the best recipe, alcohol hand sanitizers are not the most effective solution for getting rid of coronavirus. Both WHO and CDC agree that normal soap and water are the best solution for hand hygiene. They’re a lot cheaper than hand sanitizers and not subjected to panic buying. Use soap and water while working from home or in office. Use hand sanitizer when and only when soap and water are not available in public areas. Alexa provides good information on hand washing and alcohol-based hand sanitizers.

Wash hands and be socially responsible.

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