6 minute read
How to mix and manufacture compliant hand sanitiser
Designed to be an alternative to washing hands with water and surfactants, hand sanitisers reduce the viral and bacterial load on skin. While they don’t necessarily kill everything, viruses such as COVID-19 are more susceptible when using hand sanitisers. Dr Russel Walters, freelance scientist at Kolabtree, shares his expertise on how to formulate and manufacture an alcohol-based hand sanitiser quickly, easily and compliantly.
In order for a virus to infect a human host, the host needs to be exposed to a sufficient viral load, typically hundreds, thousands or tens of thousands of viral particles. Using hand sanitiser dramatically reduces the viral load on the skin, reducing infection, or infection severity.
Long, sustained exposure to an infected person is best for transmission, which makes it important to sanitise hands because they are our primary contact with the outside world. Hands can also spread viral particles when touching the eyes, mouth, food etc.
Hand sanitisers have repeatedly been shown to slow the spread of viruses and are regulated in most countries. In the US, the FDA recently liberalised manufacturing rules, creating a favourable situation for manufacturers and formulators who are new to the industry. It opens a legal path for those looking to expand into hand sanitiser supply and makes formulation straightforward. Unlike skin lotions, the options are few and constraints clear.
This article focuses on the two formulations permitted by the FDA under the recent COVID-19 guidance. The choice is yours.
INCREASED AVAILABILITY TO FIGHT THE VIRUS Before the coronavirus, in the US hand sanitisers were produced by very large, FDA-registered drug manufacturers, like Purell. However, in March 2020, the FDA issued guidance for expanded production
of hand sanitisers during COVID-19. The intention was to increase the availability of hand sanitisers by opening up which entities could manufacture them beyond previously licensed or registered drug manufacturers. However, the authority is still very specific on the actual formulations, permitting two possible options, which are either ethanol or isopropanol.
The World Health Organization (WHO) has also released an excellent step-bystep guide for the production of hand sanitisers in various regions. The two formulation options recommended by the WHO are the same as those proposed by the FDA. Both are explained below.
INGREDIENTS AND PROCESSING According to the guidelines, the hand sanitiser must be manufactured using only the following ingredients: either ethanol or isopropanol, glycerine, hydrogen peroxide and sterile water. Combine the four ingredients, mix them with care, and you have a hand sanitiser ready for the new post-COVID-19 world.
The proportion of ingredients is specified in volume percent – but be aware of the difference between volume percent and weight percent. There is a big difference, because different ingredients have different densities. While water has a density of 1g/cm3, ethanol has a density of 0.789g/cm3.
Also note that most raw materials are not supplied as 100% pure, single ingredients, and they often contain some water. Ethanol is typically supplied as 95% ethanol and 5% water, or 190 proof. So, you need to factor the raw material composition into your calculations.
Users tend to really like fragrances in skin care products, but in hand sanitisers these ingredients are not needed and will increase the raw material prices of your product.
ACCESS MORE CONTENT ONLINE ON HAND SANITISERS: • a video on how hand sanitisers work: https://bit.ly/2XOpKVp • WHO guide to hand sanitiser production: https://bit.ly/3dSHLHq • FDA hand sanitiser guidance: https://bit. ly/2XQZnOC • Gojo technical publications on hand hygiene education: https://bit. ly/3dQSO3U • extensive details and background from
USP: https://bit.ly/37eRzJx.
In skin care products, fragrances are often used to cover the underlying base odour, but this is unnecessary in hand sanitisers as their base odour is minimal.
Under the FDA COVID hand sanitiser guidance, fragrances and skin benefit ingredients are explicitly not allowed.
TIPS TO CONSIDER The two simple water/alcohol formulas included in this article will be water-thin and easily sprayable. However, hand sanitiser gels, like Purell, use polymers to increase the viscosity, which can add some significant complications in the manufacturing process.
Although thickening polymers are not part of the FDA formula described above, you may want to read more about the different polymeric options for thickening a water/alcohol solution.
Boiling is the easiest and most likely source of sterile water. But be careful of heating and boiling water near the highproof, flammable alcohol.
While there are a few sources of ethanol, it’s important to note it must be denatured, i.e. made to taste bad to avoid consumption.
Mixing the components together is relatively straightforward, with one caveat – passivation. If you are using a glass or fibreglass vessel to mix your hand sanitiser, then passivation is not a concern. However, if you are using a metal vessel, you will need to be aware that, in the presence of metal ions from the vessel, the hydrogen peroxide rapidly breaks down to water and oxygen.
Ensuring alcohol evaporation is limited between production and use is another important consideration. The packaging must seal sufficiently. Manual pumps are explicitly allowed in the FDA guidance.
Ethanol is a natural product with natural antimicrobials, yet efficacy data on them is limited. As hand sanitisers are regulated, in order to label and market a product as a hand sanitiser, the FDA guidelines must be met.
SKIN SAFETY AND ALLERGIES Hand sanitisers are likely better for the skin barrier than repeated washing with soap. Cleansing with soap often removes skin components and can disrupt the natural structure of the skin. In contrast, after killing bugs on the skin, the alcohol in hand sanitisers rapidly evaporates and has little impact on the skin barrier.
Therefore, the core of your hand sanitiser formula should not cause any skin problems. Furthermore, fragrance is often the source of skin irritation, especially an allergenic response.
TESTING Many problems are solved if you follow the FDA guidance on hand sanitisers and there is no need to test the bug-killing efficacy of your formula.
Hand sanitisers based on the formulas outlined in this article are well-proven to effectively kill bugs and be safe for the user. You will simply need to check that after production, the alcohol level – ethanol or isopropyl alcohol – is validated by physical chemistry means such as an alcoholmeter or hydrometer.
If you’re looking for a freelance scientist to help you begin manufacturing hand sanitiser, you can visit the Kolabtree website to post your project for free. •
ABOUT THE AUTHOR Previously a research fellow at J&J, Dr Russel Walters (PhD) has developed skin care technologies that were launched into dozens of products and 100s of SKUs. He is a prolific inventor with more than 20 US patents and is an active researcher with more than 35 scientific articles published. Dr Walters is on the scientific advisory board of Cosmetics & Toiletries magazine. As the co-founder and CTO of Somn, Dr Walters also consults in the personal care and digital health spaces. •
Kolabtree – www.kolabtree.com
