-
Please help! Hand sanitizers formula
Dear all,
I’m thinking of making 50x 60mL Hand sanitizers for the clinic that I currently work at. (I’m a pharmacist) I happen to have 99.97% Ethanol at home.
Below is my formula:
70% w/w Ethanol (100%)
5% w/w 1,3-Propanediol (DuPont)
5% w/w Aloe Barbadensis extract
1% w/w Sepimax ZEN
1% w/w Tocopherol acetate
0.3% w/w Lavender oil
qs. Distilled water
(100%)However, here in Taipei (Taiwan), I can’t source Sepimax ZEN. I have Xanthan Gum… any suggestions for any other alternative thickeners suitable for this formulation? Im sorry i dont have much experience!
Also, should i add glycerin as well?
Thank you!! Any help is greatly appreciated
-
40 Replies
-
You have to ask yourself since the beginning. Do you really need to have a gel?
If yes, xanthan gum can work. Still, don’t expect any good viscosity. You can use carbomer if you have.
What is the reason of Aloe in your formulation?
There is no need for glycerin as long as you have 1,3-Propanediol in your formulation. -
Get rid of the aloe, tocopherol & lavender oil. When making a functional product like hand sanitizer you shouldn’t be adding superfluous ingredients.
You should get Carbomer if you are going to thicken the product. Xanthan & Sepimax Zen are too salt tolerant and won’t properly release the alcohol. You likely won’t get the kill rate necessary for the product to work.
-
em88 said:You have to ask yourself since the beginning. Do you really need to have a gel?
If yes, xanthan gum can work. Still, don’t expect any good viscosity. You can use carbomer if you have.
What is the reason of Aloe in your formulation?
There is no need for glycerin as long as you have 1,3-Propanediol in your formulation.I’ve changed my mind since. Will be making an hand sanitizing spray. Going to forget about Xanthan and Sepimax Zen (also because I can’t source it here in Taipei). Aloe is in there for its soothing and moisturizing properties, but maybe I should leave it out? (Thank you so much for your input. I really appreciate it)
Perry said:Get rid of the aloe, tocopherol & lavender oil. When making a functional product like hand sanitizer you shouldn’t be adding superfluous ingredients.You should get Carbomer if you are going to thicken the product. Xanthan & Sepimax Zen are too salt tolerant and won’t properly release the alcohol. You likely won’t get the kill rate necessary for the product to work.
Thank you Perry. Will Aloe, Tocopherol & Lavender dampen the effectiveness of my hand sanitizing product?
Ah I see! So carbomer is the way to go if I was going to make a gel-form. I’ve since decided to switch my formula to spray form. Just having Water, Ethanol and Propanediol. Thanks again!
-
Hi @Perry, may I ask you to explain why electrolyte tolerant gel makers won’t release alcohol, please? How does that mechanism work?
-
I’ve changed my mind since. Will be making an hand sanitizing spray.
Glad you’ve changed your mind towards a liquid product, that definitely is the safe choice. However, sprays will not dispense enough product. It seems to be little known that one needs about 3ml per application so that hands stay wet for the 30 seconds required for full effectiveness. (If you don’t believe me, try doing the WHO hand rub steps after spraying your hands with sanitizer - they will likely be dry by the time you get to step 2 or 3: https://www.youtube.com/watch?v=ZnSjFr6J9HI)
It’s best to use a pump for dispensing, alternatively use a flip top bottle or similar. -
@Perry @ngarayeva001
I do not think the video is telling a full story, particularly when it says “it releases alcohol”.
Alcohol is the solvent, it’s not ab-/ad-sorbed by the polymer (like it would on a sponge). The formation and disruption of a gelation network is minimally influential on the activity of the sol phase.Activity of the solvent changes only in proximity of the gel fibrillar network.
In most cases, the formation of the fibrillar network is adjuvated (and dependant of) the solvent.Most hydrophilic polymer gelators have a very large and negative hydration enthalpy, thereby indicating that they are stabilized by forming ionic and hydrogen bonding interactions with the solvent. In the case of carbomer, this is even more true, as the polymer itself is a polycarboxylate (ionic).
Most of the solvent (water and ethanol) will not be partitioning into the fiber-network. In fact, most of it will be the bulk of the solvent, with only a minimal fraction being “adsorbed” by the fiber-network.
Hence, the bulk of the ethanol will still be ethanol (or isopropyl alcohol), with exactly the same activity as a non-gelled solution.Furthermore, I am skeptical about the amount of salt referred to in the video.
It takes a few seconds for a pinch of salt to act on the gel, while it takes almost no time for the gel on the hands to liquefy.
I doubt that the amount of electrolytes on our skin (or their activity) is such that it behaves like a concentrated NaCl solution.
Temperature difference and shear-thinning would be my first culprits. -
Thank you all for the contribution. All I can say is Wow! A question leads to all these amazing discussions.
If Xanthan gum / Sepimax impedes the release of alcohol, does that mean it’ll also slow down the release of actives if used in other products like serum or moisturizing gel?Thanks again. Much appreciated
-
Perry said:@ngarayeva001 - See this video explanation.
https://spark.adobe.com/video/XvyTzaDX0UiNp?w=_1397&fbclid=IwAR3PHCj64hEJjwyqrIRj6oSgPsaQLXo3wFskIRvnxeMKsx0wL56hbwb4nukThat’s propaganda! It is not a reliable source of information. I was expecting an article comparing the efficacity of gels using different types of polymers.
In my point of view, there is no release of ethanol by destroying the structure of the gel. It is like saying, you have to destabilize a cream to get the efficacy of the oils. -
@em88, it is not as illogical as it seems.
It might be true if ethanol (or IPA) were in the discontinuous phase of an emulsion.
This happens with oils and gel emulsifiers, where the oils are dispersed as the discontinuous phase in a O/W colloid. In order to form a film, the oil droplets need to coalesce.
Now, if we would translate this to a hypothetical alcohol/water colloid (mind, it does not exist, as alcohol and water are fully miscible) this “gel breaking” would make sense, as we know that we need to achieve a certain local concentration of alcohol for it to be effective at sanitizing.But it is not a real scenario. Hand sanitizers are not proper emulsions, with discontinuous/continuous phases, yet, from the chemical point of view, they are not homogeneous mixtures, because the gel network constitute a separate phase that is in equilibrium with the sol phase. The concentration and activity of alcohol is the same, within statistical difference, whether as a liquid or as a gel.
If there is a difference between the two, we will never know why, because a control experiment will require removal of the gel phase, but that is exactly what we are trying to show.
I’ve whipped together a 75% ipa gel with Sepimax Zen (1.3%) yesterday. Quite unsurprisingly to me, it behaves just like in the video. There is a layer of “more liquid” gel at the interface between the glob of gel and my hand, and if I swish it around, it liquefies. This is exactly the same effect on:
I) unwashed hands
II) hands washed with soap and dried with clean towel and air for 2 minutes
Thus taking into account the presence of electrolytes from my palm perspiration.I’ve checked the whole of R. Lockhead publications, and the only publications on this topic are relative to O/W coalescence. He has done plenty of rheology of gels in presence of electrolytes. But there is no mention of its effect on sanitizers.
It doesn’t help much that 50% of its publications are abstracts from conferences, which are scientifically irrelevant. -
@lmosca Thank you for your enlightening posts on this.
-
Amazing quality posts… thank you all.
I am not trained professionally as a cosmetic chemist. But ever since taking up a course in simple&complex compounding w/ PCCA, I fell in love with formulating. This is so much more interesting than being a pharmacist dispensing Tylenol everyday. Hah!
@lmosca Where did you get trained as a cosmetic chemist? Your answers are so in-depth!
-
@em88 - the video was put together by one of the most respected polymer scientists in the industry. Dr Lochead does not work for the Carbomer manufacturer and this isn’t propaganda.
As to the veracity of the video, I cannot comment as polymer science is not my area of specialty. I’m in no position to dispute what Dr Lochead has communicated. He could be correct, or he could be wrong. I certainly wouldn’t suggest his work is suspect based on my own ideas & a solution I made up in my kitchen and tested on my hands.
Just as I’m not going to tell climate scientists they are wrong because I’ve read a few articles on the Internet & noticed winter is colder these days, I’m also not going to say Dr. Lochead is wrong & he’s certainly not pushing propaganda.
@lmosca - I appreciate your input and you raise interesting questions. I too find it surprising that such a mechanism would be necessary for these hand sanitizers to be effective. But I have no good reason to doubt him & have no reason to trust your alternative assessment (although you could be right).
-
@steamedrice, I am not a formally trained cosmetic chemist.
I am, by education and training, first an inorganic chemist, who then became an organic chemist. That’s what I do for a living now. I’ve worked on sensors and supramolecular gels. Now I am working on self-assembly, self-replication, molecular machines and systems away from equilibrium.
All that I’ve learned about formulating, I’ve learned through books, articles, and places like this. Having a formal education in chemistry is perhaps an advantage, I consider myself very fortunate because where I received my education from, classes and labs that teach you about industrial chemistry, pharmacology, emulsion technology, and other related topics where free to add to anyone’s curriculum. More than fortunate, my university had a uniquely powerful pharmaceutical chemistry department in the whole country.
Eventually, about 4-5 years ago, I felt ready to start buying equipment and ingredients. I still do my 10 hours of chemistry in the lab, and formulate stuff in the evening, or read mostly scientific publications (cosmetics and not). -
Very interesting @lmosca can I know your University? actually i look forward to learning pharmaceutical chemistry sciences.
I’am process chemical engineer and i’am fun of aromatherapy and pharmaceutical sciences so I think it will be amaizing to have pharmaceutical course in my case. -
@lmosca - like I said, I’m appreciate your input. It’s always good to get science-grounded opinions.
The reality is that the cosmetic industry and cosmetic science in general suffers from a lack of scientific rigor (in my opinion). Much of the “research” is sponsored by companies who are motivated to get formulators to use their ingredients or cosmetic marketers who want to convince consumers that their products are better than someone else’s. And there are a lot of opinions from people with years of experience who pass along information they’ve long believed but is not necessarily scientifically validated. In truth, I believe many questions are left unstudied mostly because there is no financial value in learning what’s true.
However, Dr. Lochead is actually one of the few researchers involved in the cosmetic industry with both formulating and academic research experience so I respect his views on the subjects for which he offers opinions.
-
@lmosca Thank you! One more question (since you’re amazing at what you do), as a beginner where should i begin? Any books/any resources you recommend? Thank you!!!!! Really appreciate it
-
@em88 To add to what Perry wrote, Robert Lochhead is for sure one of the most prominent figures in rheology modifiers and polymeric gelators for the personal care industry (and not only that). He was chair of the Department of polymer chemistry at the University of Southern Mississippi (which is probably one of the most prestigious polymer schools in US), where he is now emeritus professor. He was also president of the Society of Cosmetic Chemists, and before that he worked for BFGoodrich and Unilever. So he is definitely not uninformed on the topic.
@Perry, this is a link to the first patent that mentions quick breaking upon contact with skin. https://patents.justia.com/patent/5004598
While it is mentioned several times, there is no reference to further data to support this.
In other words, yes, quick break of the gel with concomitant loss of viscosity does happen on the skin. As to why, there is no explicit support data that it is caused by electrolytes from perspiration. Other things can influence the viscosity of the gel, like the surface temperature of the skin, or the shearing when pumping/moving/rubbing, or all three of those parameters.Unfortunately we are in the murky realm of industrial intellectual property protection, patents etcetera… Disclosing full data is not something that companies do, because it may hinder future patent protection or loss of market due to a competing firm.
What I mean is, this data might be existing somewhere, it’s just not public or passed by my radar.
This (the gel quick break) is not a simple problem, and it has, as it stands, 4 different variables to isolate (in reality there will be even more, like pH, type of polymer, concentration of every component in the formula, and so on). Just the design of control experiments to get a real answer could be a massive enterprise, in terms of capital, for a medium-large sized company.
And that is just to try to identify the stimulus (input/action) - response (output/reaction) side of it.
As for he why, that’s a different story altogether. Knowing how something reacts and to what, doesn’t necessarily mean why it does/doesn’t work. For what concern gels (polymers or low-molecular weight) I can say for direct experience that there has been a constant improvement in the knowledge of why things work a certain why in gels. However, I feel we will still have one or two lifetimes in front of us before we can fully understand all of the detailed intricacies of gels.
In other words, if we compared emulsion technology and emulsion science, both mature, well developed fields, with gel technology (the how to), would be considered a 21 years old, and gel science (the why) would be an elementary school kid.I do agree with you. I wouldn’t dismiss Lochhead’s opinion. But it just sounded strange, and too simplistic, at first.
-
@lmosca and @Perry, I’m not saying anything about the person who did, whatever he did. There is a big issue in the video which is not taken into consideration, friction forces! It is supposed to rub your hands with the gel. By rubbing is usually meant to put some force, not just spreading the gel over the hands. While rubbing your hand with the gel, you destroy all kind of gel structures at the point that all the liquid (ethanol, water, and other polyols) are released from the gel structure and begins to evaporate. That is why at the end of the rubbing you are left with the sticky feeling since only the polymer is left on the hands.
Again, I would very strongly appreciate and use that knowledge if the test is actually done in comparison with the efficacy, not just by dropping some gel on the table, destroying the gel structure and say, “See? Now the ethanol is free from the gel.”@lmosca, one friendly suggestion. With all the respect, your posts are very wordy. Try reaching your point in fewer sentences. It will help readers very much.
-
Perhaps there is a forest somewhere in all these trees!
The main issue is the contact time required for the alcohol to denature the viral proteins which is in the range 20 to 30 seconds. It really does not matter if you use a spray or a gel. Simply spray 1 pump wait 15 seconds, spray another pump. Or, use a gel.
-
MarkBroussard said:Perhaps there is a forest somewhere in all these trees!
The main issue is the contact time required for the alcohol to denature the viral proteins which is in the range 20 to 30 seconds. It really does not matter if you use a spray or a gel. Simply spray 1 pump wait 15 seconds, spray another pump. Or, use a gel.
That is very correct. The contact time is very important and it is always considered as a factor in the efficacy test.
-
Hi everyone,
Has anyone here had any experience with Aristoflex AVC? I’ve recently tried it in small batches up to 80% ethanol with good results.
-
It really does
not matter if you use a spray or a gel. Simply spray 1 pump wait 15
seconds, spray another pump. Or, use a gel.As a medical professional, I feel a duty to point out that sprays are absolutely not appropriate for hand sanitization. This is a very common but dangerous misconception due to many sanitizers being wrongly sold as sprays.It is true that liquids work just as well as gels, if not better. But you do need to use the same amount of both and apply them the same way: pour/pump ~3ml in the palm of one hand, then perform the WHO recommended handrub steps (which are the same steps as used for hand washing): https://www.youtube.com/watch?v=B3eq5fLzAOo -
@Agate
Why would it be inappropriate and dangerous to sell as a spray? The formula doesn’t really change properties being aerosolized (if anything, could one not argue it would be advantageous as smaller droplet size increase likelyhood of penetrating harder to reach areas such as under nails?)
The only issue I could see would be something like improper contact time but that would derive from human error not following instructions as opposed to the delivery method.
Log in to reply.