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Composition of Alcohol in Alcohol based sanitizers.
Greetings to everyone.
This query is related to the composition of alcohol in alcohol based hand sanitizers. Organizations like CDC,EPA,WHO recommends alcohol based sanitizers having 60-95% concentration of alcohol. However it mentions nowhere whether the recommended concentration should be weight/weight or volume/volume or weight/volume. Secondly, which grade of ethanol is required ? Can we use Ethanol 96% which is used in perfumes industries ?
Your wise response is eagerly awaited.
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35 Replies
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The official recommendation is on a volume/volume base; 70-80% ethanol, or 60-80% isopropanol, n-propanol or a mixture of all three is the current % against the corona virus. Weight-wise, 63% w/w would correspond to 70% v/v and therefore, your range might indeed be on a w/w basis but it’s not, read the CDC guidelines. Given that higher % are more effective against viruses, the range can, again with regard to the corona virus, go as high as pure ethanol. w/v is usually not used.It does not matter what exactly is in it as long as the % of alcohols is within the antiviral range. In case of ‘perfume’ ethanol, also called ARO ethanol, the denaturant is commonly rosemary extract which doesn’t smell but gives the ethanol a bitter, undrinkable taste. This denaturant does not hamper antimicrobial efficacy and you’re absolutely fine and safe using it.On the other hand, you should refrain from adding other stuff (except for glycerol which is proven safe at up to 1.45%) because it might decrease efficacy. Sure, certain additives do increase it, others should, and yet others at least boost antibacterial efficacy but if you’re not 100% sure which ones do what, better don’t add any. -
Considering 70% v/v concentration of Ethanol 99.9 % denatured in the finished product, is it 700 liter Ethanol 99.9% and 300 liter demineralized water for a 1000 liter batch of finished product ?
Is it true that if Ethanol 96% is used, it should not have any Methanol content ?
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Your calculation is correct (neglecting rounding errors). Quesiton: Why use 99.9% ethanol? This dried ethanol is usually more expensive than commonly distilled 96% ethanol. As long as you correctly adjust the amounts (consider density-changes upon dilution!), it does not matter which one you use.Ethanol, unless industrial one for burning or synthesis, should contain methanol. Ask your supplier whether it does not not. Do not use methanol-containing products! This stuff goes through skin (and lungs) and can cause blindness amongst other severe and irreversible damages to your health.
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Considering 96% Ethanol, for achieving the same 70% v/v concentration of the finished product we require 729 liters of Ethanol and 271 liters of demineralized water to make a 1000 liters batch of finished product.
The SDS of both grades of Ethanol contain methanol in trace quantities. Furthermore is it fine if we exclude the addition of glycerol ?
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Trace amounts are more or less common and difficult to remove. You’ll be fine.Glycerol is not needed, it’s in there as skin conditioning agent in order to not dry your hands out too much.
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So will ethanol and water do the trick?
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That’s correct
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Thanks.
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@Pharma Typo? (80%v/v) or am I missing a step here?
(63%w/w) x (.789g/ml) = (79.85% v/v)
Pharma said:
The official recommendation is on a volume/volume base; 70-80% ethanol, or 60-80% isopropanol, n-propanol or a mixture of all three is the current % against the corona virus. Weight-wise, 63% w/w would correspond to 70% v/v and therefore, your range might indeed be on a w/w basis but it’s not, read the CDC guidelines. -
RDchemist15 said:@Pharma Typo? (80%v/v) or am I missing a step here?
…No typo. The fact you’re probably missing is that mixing x grams of ethanol with y grams of water will result in volume depression. You can hence not use density of pure ethanol for your calculation but have to consider density of 63% w/w or 70% v/v, respectively.
Likewise, mixing 630 g ethanol with 270 g water will not result in 1 litre. Therefore, it’s not advised to just weigh the required amount of ethanol and top of with water to 1 litre because during this manipulation a certain mixing of both liquids at the interphase will take place and mess up your calculations and as a result the final %. -
@Pharma Yep. Volume depression was what I wasn’t accounting for. Thanks
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Is it appropriate to store Ethanol 99.9 % in IBCs or HDPE drums ???
I observed a company selling Ethanol 96% packed in HDPE drums which was to be used in perfumes Industries.
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Can’t say without testing. Pure ethanol is dangerous to handle. I used to store it in 1 gallon glass bottles but one day I dropped one and created a dangerous situation. Pure alcohol attacks many substances including neoprene rubber, I can tell you that.
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We receive our 200 proof USP ethanol in HDPE bottles. Should be fine and doesn’t carry the risk of shattering like glass if inadvertently dropped.
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Is it wise to use alcohol based sanitizer for surface sanitization ?
Are there any other alternatives which are economically better and equally or more efficient than alcohol based sanitizer when it comes to surface sanitization ?
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For surfaces there are plenty of viable non-alcoholic sanitization methods, chemical and physical.
UV light, superheated steam are two of the most common physical sanitation methods for flat surfaces.
Chemical methods can vary and are very much dependent of the surfaces you will sanitize.
- Bleach and hypochlorous acid - corrosive to metals, can yellow plastic laminates, smells like overchlorinated pool (love it, personally).
- Formaldehyde, formaldehyde formers (the first abandoned in most jurisdictions, due to volatility and toxicity.
- Hydrogen peroxide, non-corrosive, doesn’t leave residues, shelf stability of concentrated solutions is not great, usually used at lower concentrations. With acetic acid or formic acid forms peracetic and performic acid, which are great germicides.
- Organic germicides, like chloroxylenol (dettol, in some countries), benzalkonium chloride, biguanide-based, etc… good on surfaces, usually require longer contact time to act, and sometimes they have reduced activity depending on microbial load and/or in presence of other organic debris. They are not omni-potent against spores or viruses.
- Here in the US we have access to a concentrated product called Star-san (Fivestarchemicals). It is good on most surfaces (but not metal) and does not require rinsing. It is a mixture of phosphoric acid and sodium dodecylbenzenesulfonate. It is used for sanitization by homebrewers and even by some cosmetic diy-ers.There are even more, but this is what I could think on the spot.
The main questions you want to ask yourself is:> What do you want to kill (molds, bacteria, viruses, multi-spectrum)
> How fast should it be?
> How toxic is it to humans, animals, and how harmful for the environment?
> Which kind of surface is it compatible with? -
MurtazaHakim said:Is it appropriate to store Ethanol 99.9 % in IBCs or HDPE drums ???I observed a company selling Ethanol 96% packed in HDPE drums which was to be used in perfumes Industries.
yes, HDPE is extremely solvent-resistant
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MurtazaHakim said:Is it wise to use alcohol based sanitizer for surface sanitization ?
Are there any other alternatives which are economically better and equally or more efficient than alcohol based sanitizer when it comes to surface sanitization ?
- It will do a great job of sanitising and it’s also a good solvent so it cleans too, but in my opinion the negative points are many. In particular, it is readily absorbed into the bloodstream by inhalation. It is a considerable fire risk.
I experienced becoming suddenly drunk after dropping a 1-gallon glass dewar of 95% ethanol. Very quickly indeed. -
The 63% w/w is correct and is used for ethanol 96%
I guess this percentage is very common for pharmacists worldwide. 🙂 -
The Hand Sanitizer formulation recommended by WHO includes Glycerol and Hydrogen Peroxide as well. I observed a study stating that the presence of glycerol interferes in the virucidal efficacy of the product. Are there any established evidences for that ???
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I believe the inclusion of hydrogen peroxide is to improve the cleanliness of water used, as in some countries anything other than potable water is challenging to access. I haven’t heard of glycerol interfering, and I would hope that the WHO, as respected and responsible as they are, would not circulate a formula which interferes with the function for which it was intended. Can you point us towards said study? You may be able to judge by the way a study was written and the quality of its references how reliable it might be.
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Maybe it is this study? https://www.sciencedirect.com/science/article/abs/pii/S0195670113000297
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@klangridge:
Hydrogen Peroxide is included in the WHO formula primarily because it is an effective biocide against spores.
Glycerol is included in the formula as a humectant to help moisturize the skin. The study said “significantly reduces” … but they did not enumerate what they mean by “significant”
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@MarkBroussard It probably does, but my assumption was based on the following:
“Hydrogen peroxide: Used to inactivate contaminating bacterial spores in the solution and is not an active substance for hand antisepsis.”…which is taken from a Notes section on Page 2 of this WHO leaflet describing how to make hand rub formulations: https://www.who.int/gpsc/5may/Guide_to_Local_Production.pdf?ua=1
I’d guess that it would need to be at a higher concentration to have more of an effect. I wonder if that would cause more damage to the skin than repeatedly using the hand rub?
I suppose even if the glycerol does decrease efficacy, the overall formulation must still have a satisfactory effect considering it has been made publicly available. The article reads well, but a couple of points to consider: 1) The tests analysed bacterial growth, so this doesn’t tell us about its viricidal or fungicidal activity. 2) The test included only 24 volunteers, 12 of which used hand rub with glycerol, and 12 without. 3) Results are shown as Log 10, which have completely thrown me as I can’t remember exactly what Log 10 does to raw values :#
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I saw a video (http://youtu.be/PMBqueQebIE ) on UL Prospector which was from Institute of Personal Care Science. It was said that one should use undenatured grade of Ethanol in formulation of Hand Sanitizers. We are using Ethanol 99.9% DB. What does DB mean ??? Is it denatured base or something else ???
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