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Note: I am looking for advice on a chemical test - not a sermon.
I expect that this is entirely on topic in this forum, downvotes and sermon comment notwithstanding.

More than about 5% of Methanol in alcohol based hand sanitisers indicates that corners have been cut during manufacture and that the product should be avoided.

I'm looking for an easy test to determine the approximate percentage of Methanol in an Ethanol / Methanol hand sanitiser mix. Many hand sanitisers may contain small percentages of Methanol (typically in the 1% - 5% range) and this is acceptable. Anything over 5% I'd like to avoid. Much over 5% (say 10% +) I'd like to be very clearly distinguished. If actual approximate percentage can be indicated, so much the better.

Ideally I'd like a test with either low cost, simple to use, readily available non-hazardous reagents (one can hope) or failing that, something that can be prepackaged for easy use by the unskilled.

In web searches I found a range of tests for Methanol but most were not very quantitative and most were not intended to work in an ethanol-methanol mixture.


Background: Added:

Some guy y'know said:

Using disinfectants outside of a heathcare environment is still nonsense in the year 2020. Using disinfectants of questionable provenience is simply hazardous. Don´t do it.

The use of hand sanitisers is well covered in recommendation documents from regulatory authorities in many administrations and by internationally relevant bodies. Sanitisers are sold under regulatory guidelines which if followed would guarantee their safety when used appropriately. In the US many out of specification brands are being sold which are indistinguishable from those which comply. Several of the largest US sellers have been selling out of spec product. There is no way to determine provenance based on labelling.

While the use of soap and water is often a good or even superior solution it is incorrect to suggest that the use of sanitisers in general applications is nonsense.

In this instance I am interested NOT in their efficacy or application but re their specific bonafides with respect to a crucial component which is known to be used in excessive and illegal amounts in some cases.

I'm an engineer. Sanitisers are sold by a wide range of manufacturers and repackagers. I read labels, note sources, note claimed contents and viscosities and residence times and more.

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    $\begingroup$ Using disinfectants outside of a heathcare environment is still nonsense in the year 2020. Using disinfectants of questionable provenience is simply hazardous. Don´t do it. $\endgroup$ – Karl Aug 1 at 12:13
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    $\begingroup$ There's no such test. Methanol is very similar to ethanol. Perhaps it could be selectively oxidised, but strong oxidisers aren't particularly safe or freely available. $\endgroup$ – Mithoron Aug 1 at 14:31
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    $\begingroup$ You could conceivably use mass spec or NMR, but neither method is conveniently available outside of labs. But to be fair, methanol is perfectly fine, provided you're not inhaling large amounts, swimming in it, or drinking it. $\endgroup$ – Zhe 2 days ago
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    $\begingroup$ @Zhe For information. Some santisers in the US have been found to have only Methanol or high percentages of Methanol. These are reported to all or mostly have been manufactured in Mexico but I imagine labels are unlikely to reflect this. Reports indicate that regular use over 2 days can start to cause vision effects and blindness. This is also reportedly reversible if use is then stopped. It would be very useful if such products could be reaily detected in advance. My interest covers not only NZ where I live but other countries who may be being taken advantage of in the present circumstances. $\endgroup$ – Russell McMahon 2 days ago
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    $\begingroup$ @RussellMcMahon If you're talking the composition being primarily methanol, that is very different from having some fraction of methanol. I think the main point is that the analysis you're talking about is non-trivial... $\endgroup$ – Zhe 2 days ago
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Russell, agree with your down voting frustration but it is a common problem of any public forum. The bad news is that "simple" distinguishing test do exist, but they generate more toxic products (including a carcinogen) in a so-called iodoform test. Good for school labs only. The problem is not in distinguishing methanol versus ethanol, the problem is the matrix (as analytical chemists call it), i.e., these alcohols are present in a complex mixture.

The only reliable test test to determine methanol in a complex mixture like a hand sanitizer is gas chromatography. You need to consult a professional certified service to ask them to analyze the sanitizer. There is no home-kit or simple test to differentiate the two in a mixture.

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    $\begingroup$ DV has now been followed by question closure :-). I've been active on SE for 9+ years, I'm in 50+ stack exchange groups where I have more than the basic 101 points and another 30 with ~= 101 rep. I'm a moderator of an active SE site. I have a reasonable idea of how to ask good questions on SE. I find the reactions here 'interesting'. I'm aware that in some groups it seem obligatory to give newcomers a hard time (and do not know if this is the case here), but it's an interesting experience. | I'm astounded that anyone thinks they could not perceive a focused question in my original post. :-) $\endgroup$ – Russell McMahon 2 days ago
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    $\begingroup$ Russell McMahon, I am one of the major opponents of this unnecessary down voting issue in chemistry. I guess, it gives some people a dopamine boost. Chemistry also receives low quality queries from students as well because chemistry teachers at many schools are not that great. Anyway, you should not care on the other hand, because faceless and nameless people down voting a decent question have zero importance outside the internet (equivalent to generating a storm in a tea cup). ResearchGate disabled down voting option altogether. $\endgroup$ – M. Farooq 2 days ago
  • $\begingroup$ I disagree with this absolute negative response and I plan on testing the burning splint variation (testing actually for oxygen) with a methanol/glycerine mixture on leaves versus ethanol/glycerine. For CH3OH, expect less CO2 and more pure O2. It will be fun and further fascinating if this biological-based experiment (based on a ScienceDirect article) that is performed on three plants (one with ethanol, and two with different doses of methanol) can actually roughly estimate the CH3OH loading. $\endgroup$ – AJKOER 2 days ago
  • $\begingroup$ @AJKOER Any practical results that you achieve would be of interest. $\endgroup$ – Russell McMahon yesterday
  • $\begingroup$ Not sure if I can achieve practical results. One obstacle that I have already been confronted with (source: a younger member of my family), is that it is advisable to talk to the plants. Perhaps I should have listened to my esteem colleagues. $\endgroup$ – AJKOER yesterday
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It is likely that without sophisticated equipment that one cannot accurately determine methanol concentration.

That being said, my speculation on a possible process, for possible use outside of the lab, could be based on this source outline of relevant chemistry, to quote:

Methanol influences the oxidizing capacity of the atmosphere through reaction with the hydroxyl radical (Jiménez et al., 2003), its main sink, leading to the formation of water vapour and either CH3O or CH2OH radicals, which both react with O2 to give HO2 and formaldehyde (H2CO) (Millet et al., 2006 ). The photo-oxidation of formaldehyde, a key intermediate in the oxidation of numerous volatile organic compounds , leads to the formation of HO2 radicals and carbon monoxide (CO). ...

As such, consider an experiment consisting of placing a test sample of the hand sanitizer in an expandable transparent plastic bag along with some B-12 mixed with 3% H2O2 (which was shortly before made alkaline by adding Na2CO3 until CO2 evolution ceased) in direct sunlight. Periodically shake.

My expectation: The B-12 is a photocatalyst that turns clear with sunlight exposure. Some hydroxyl radicals, along with CO and O2 are produced in the reaction from the breakdown of the H2O2 and importantly, the CH3OH (methanol) in direct sunlight in the presence of B-12. The alluded to HO2 radical above at pH>5 (from the added alkaline Na2CO3) is now in the form of gaseous superoxide ($\ce{.O2-}$).

Perform a parallel run employing ethanol mixed with an ethanol-based hand sanitizer. The chemistry on photolysis differs and is discussed here.

Comparatively, I would expect a faster reaction with methanol over ethanol (accelerated loss of the B-12 coloration) and more/faster gas creation. If I am wrong on the latter point, not material, as it is still likely quantitatively different.

You may be able to use the measured timing of the volume of gas along with the timing of coloration lose, to assess relative methanol presence.

Note: Unfortunately, there is more than alcohol added to hand sanitizer mix (like a moisturizer, perhaps glycerine) which may make the comparative analysis even harder.

[EDIT] Now, some may have suspected that my suggested photolysis experiment was a bit far afield from classical analytical chemistry. Wrong, this experiment is definitely more so, but even greener, likely easy to implement at home, and decidedly fun. Select two (or more) small nearly identical green plants, treat the leaves of one with a glycerine/methanol mix and with the other substitute ethanol. Place each plant in a container which has been fulfilled with a fixed amount CO2 gas, but still should have some remaining air (plants apparently need to breathe O2 at night, but during daylight, on net, produce much more oxygen from CO2) where the very top part of the plant should be exposed to air. Place the open mouth vessel with the plant in sunlight with a thin transparent plastic seal. The plant demonstrating a greater consumption of CO2 and corresponding formation of pure oxyen can be tested by placing a glowing splint into the vessel. Record the seconds and/or the splint's position in the vessel until the burning bright oxygen flame is reduced/extinguished. This may produce a relative metric to judge the relative presence of methanol given its apparent photocatalytic acceleration of a leaf's ability for oxygen formation in sunlight.

Here is a supporting Science Direct source, to quote:

The results revealed that photosynthesis was greatly improved by methanol, as indicated by higher photosynthetic rates and stomatal conductance. The enhancement effect of methanol on photosynthesis was maintained for 3–4 days. Different methanol concentration treatments also increased intercellular CO2 concentration and transpiration rates.

As the methanol treatment is effective for days, repetition of the oxygen generation/sunlight treatment, after replenishing the CO2 supply, may be viable. Also, for very low added amounts of CH3OH, conducting a four-day trial run is recommended as time, assuming a constant rate of photosynthesis, is a multiplicative factor.

Finally, as to whether this can actually work, in practice, and could quantify variations in the concentration of CH3OH, remains to be demonstrated, AND I PLAN TO TEST IT.

By the way, the inspiration of my original photolysis path was based on my acquaintance in the photolysis literature of the reputed abilities of methanol, so the latter photosynthesis reported results with CH3OH should not be too surprising to some.

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    $\begingroup$ Sorry, this is complete non-sense. That is not how analytical chemistry works. $\endgroup$ – M. Farooq 2 days ago
  • $\begingroup$ True, I added the (obvious) qualifier, outside of one's lab. However, I have tested the relative strength of H2O2 with NaOCl at home via O2 evolution on several occasions. My photolysis suggested experiment is based on my experience working with B-12 and shares a similar gas evolution comparative path. Conducting classical analytical chemistry experiments is a luxury for many, and I am opened minded to at least consider improvising, when necessary, outside of the lab. I also suspect M. Farooq has never performed any fun experiments with direct sunlight and home photocatalyst like ZnO or B-12. $\endgroup$ – AJKOER 2 days ago
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    $\begingroup$ Ajkoer, I don't your age group, but 20 years ago, I have had all this fun which excites you now ;-). What boggles my mind, is how conveniently you drag in free radicals and bleach in almost all your answers. $\endgroup$ – M. Farooq 2 days ago
  • $\begingroup$ Actually, HOCl (in a Fenton-type reaction) and H2O2 (Fenton-like or Fenton with iron) engaging with transition metals manages to show up in disease proliferation (in our lungs and elsewhere) all by themselves (no need to drag them in), or somewhat extensively in AOP (advanced oxidation processes) to remove pollutants even, at times, using light, or more enjoyably use NaOCl (or HOCl) in a bleach battery (electrochemistry). I regret to inform all that photolysis, as the source above notes, is apparently all about radical formation and subsequent interactions (especially with O2). $\endgroup$ – AJKOER 2 days ago
  • $\begingroup$ M. Farooq, for my first suggested photolysis based approach, your comment was 'non-sense'. As I have now have gone even more 'green' (as in vegetation) with my suggested second embodiment, I eagerly await your new depiction. $\endgroup$ – AJKOER 2 days ago

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