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[Trekkin]

I mean, why wouldn't diagnostics for evolution of formaldehyde in solution when alcohol dehydrogenase enzyme is present work to find methanol, I mean, its well established chemistry and all.

Well, the main point of failure here is probably going to be the enzyme not having the activity you expect under the conditions you're providing. Yeast alcohol dehydrogenase is a problem even in theory; it's reversible, so yeast can make alcohol. So, in constructing this hypothetical assay, we have to either determine the equilibrium point between methanol and formaldehyde or work with the reaction kinetics, and both are going to depend on what else is in our unknown alcohol solution.

On top of that, we have a problem in the form of our activity assay; I notice you didn't list a spectrophotometer, but even assuming we have one (since they're certainly not painlessly inexpensive even with our $600-and-counting cost so far), we're converting MTT to Formazan in a yellow-to-red solution (since we're adding wine). That's going to complicate blanking even before we get into questions about side reactions, let alone the activity of any remaining dehydrogenase from the yeast used to make the wine in the first place. The more active our added dehydrogenase is, and therefore the more sensitive our methanol assay, the more error we can expect to introduce in our activity assay, particularly since the endogenous dehydrogenases are almost certainly not going to consist wholly of the dehydrogenase we're adding so all our kinetics from earlier are thrown off again.

Even setting all of that aside, we're running with two completely different chemical processes here at minimum and they need different reaction conditions. Our enzyme works best in yeast cytosol. Our formaldehyde test apparently doesn't work at all, according to the reviews, but we can safely assume it's not optimized to work in yeast cytosol. How much methanol and formaldehyde are we going to lose in cooling our test solution down from 30 C, let alone in leaving it there for our enzyme to work? How is everything else in the wine going to affect the test? Is the color of the wine going to color our test strip?

So yes, you can get all the shit you want from Amazon, but there's no guarantee any of it is going to work the way you think it will in combination and good reasons to think it won't, at least not to the level of being quantitative. I know you've said in the past that you're not afraid to be wrong, but it's probably best to be worried about that if the alternative is maybe drinking methanol.

[TD1]

I find myself constantly rearranging sentences I hear in everyday life so that they are aesthetically iambic. Not bad, I just sort of frown internally at myself when it happens.

[wierd]

There's a convenient way to get the formaldehyde out of the solution though, and that is by evaporating it, and testing for its vapor.

A closed vial with a test indicator inside it would be sufficient. This would neatly remove the "other stuff" in solution problem.


Also, considering that some enzymes and products can cost literally thousands of dollars per GRAM, I think the 600$ cost of a full assay kit and enough enzyme to sample several gallons of product is pretty inexpensive.

Not "20$" inexpensive, but from the comparable price standpoint, yeah-- inexpensive.


Also, your retort is one of "But you wont get good confidence on your concentrations!" in nature.  That was not really the purpose that was set out to be accomplished.  The hypothetical home chemist wants to know if drinking this wine is likely going to be harmful to him/herself, not to 6 sigma identify the concentration of methanol per mL of the beverage.

EG, there is a difference between "Is there methanol in this?",  "Is there... a LOT of methanol in this?", and "Exactly, with verifiable calibration and accounting for all sources of instrumentation failure, how much methanol is in this?"

The hobby chemist is more concerned with the first two.  Not the latter.

Sorta like how iodine can be used to check if starch is present or not, without telling you how much starch, or what kind.

[Kagus]

Sorta like how iodine can be used to check if starch is present or not, without telling you how much starch, or what kind.

I think this is a myth. I put salt on my weetabix once and nothing happened.

[Dunamisdeos]

While saying that 600$ is comparatively cheap is like saying a Corvette is cheaper than a Ferrari and therefore affordable, if you have the dough to shell out to start making your own wine on the regular, then you have the dough to make sure it isn't going to kill you. Fatally Toxic/Not Fatally Toxic would be sufficient.

[Trekkin]

While saying that 600$ is comparatively cheap is like saying a Corvette is cheaper than a Ferrari and therefore affordable, if you have the dough to shell out to start making your own wine on the regular, then you have the dough to make sure it isn't going to kill you. Fatally Toxic/Not Fatally Toxic would be sufficient.

Sure, but Fatally Toxic/ Not Fatally Toxic Or Maybe Something Broke Or Maybe I Did It Wrong is not nearly as helpful. The closest approximation of a positive control here is to add methanol to the wine, but even that won't actually tell you anything about the sensitivity.

[Il Palazzo]

Wait, how does one even possibly end up with methanol in their homebrewed wine outside of outright mixing it in?

[wierd]

Sorta like how iodine can be used to check if starch is present or not, without telling you how much starch, or what kind.

I think this is a myth. I put salt on my weetabix once and nothing happened.

Potassium Iodide is not the same as free iodine. Also, it is incorporated in small amounts in iodized table salt, not large amounts.


@Trekkin-

Agreed, it is not going to give you a strict, nor high confidence.  What it CAN tell you, is if you have a fairly strong formaldehyde signal or not, which should prompt you to either "think better of it", or, if you are still genuinely curious, send a sample to an analytics lab, and ask for a bulk constitutional analysis along with another wad of bills.

Why bother with the latter?  Evolution of methanol instead of ethanol could be indicative of either contaminants in your fermentation equipment, or improperly regulated temperature/light exposure during that process.  It can help you to know what exactly when wrong so you can fix it.

@palazzo

Fermentation (especially home-brewing) is a very... Hmm... poorly controlled reaction process, with lots of improperly controlled/unrepeatable variables.  Ideal fermentation produces very little if any methanol. However, since we are not likely talking about well controlled batch processes here, the possible addition of unwanted organisms during processing, etc-- there is a risk of producing undesirable substances, methanol being one of them.

You find this more with sour-mash style fermentation, which is why making moonshine is such a dangerous thing, and why you cannot sell moonshine.  However, since wine making ALSO uses wild yeasts, the potential exists, but is less pronounced.

[Loud Whispers]

I find myself constantly rearranging sentences I hear in everyday life so that they are aesthetically iambic. Not bad, I just sort of frown internally at myself when it happens.

People do tend towards a natural rhythm 2 B Qwite ionest fam a lam a ding dong

[TD1]

Thou shalt of Shakespeare read
As troth I know thee will
And there take rhythm for a seed
To heareth, ay, to have your fill

[Il Palazzo]

Fermentation (especially home-brewing) is a very... Hmm... poorly controlled reaction process, with lots of improperly controlled/unrepeatable variables.  Ideal fermentation produces very little if any methanol. However, since we are not likely talking about well controlled batch processes here, the possible addition of unwanted organisms during processing, etc-- there is a risk of producing undesirable substances, methanol being one of them.

Honestly, that's the first I'm hearing about it, despite there being a long standing culture of homebrewing in my country. Does this actually ever happen? Like, was there ever a case of somebody brewing wine and getting methanol poisoning from it? (I'm not talking about adulterated wine, or amounts below toxic levels)

[Trekkin]

@Trekkin-

Agreed, it is not going to give you a strict, nor high confidence.  What it CAN tell you, is if you have a fairly strong formaldehyde signal or not, which should prompt you to either "think better of it", or, if you are still genuinely curious, send a sample to an analytics lab, and ask for a bulk constitutional analysis along with another wad of bills.

I'm not arguing that it can tell you that, but that's not actually what you want to know. You want to know if there's any methanol in the original solution, and between that and your formaldehyde readout is a significant source of Type II error in the form of an enzyme of uncertain activity in a solution with unknown contents. To give a silly metaphor as people like to do here, it's the difference between "the door is not trapped" and "you don't detect any traps" but with more blindness.

I think Gastec still makes methanol test cylinders for about $8 a pop, although the pump will run you $400. Alternatively, there are always various permutations of iodoform testing combined with distillation. I'd trust a home chemist to do either of those before I'd try enzymes, which is not to say I'd actually drink anything they'd made.

[hector13]

Was flicking through Facebook and a family member (two, really) posted a bunch of comments on a picture of a... presumably negative statistic regarding a political figure of the party I support.

Decided on a whim to check the comments. Evidently political discourse doesn’t involve discussing the veracity of said statistic, how it relates to them somehow compromising their politics, or even how it fares compared to other politicians of various stripes, but saying the person in question needs to brush their hair.

“I agree with them I them on the economy, on education, on welfare and healthcare. I’d vote for them, if only they didn’t look like they were fired through a hedge backwards.”

[wierd]

Fermentation (especially home-brewing) is a very... Hmm... poorly controlled reaction process, with lots of improperly controlled/unrepeatable variables.  Ideal fermentation produces very little if any methanol. However, since we are not likely talking about well controlled batch processes here, the possible addition of unwanted organisms during processing, etc-- there is a risk of producing undesirable substances, methanol being one of them.

Honestly, that's the first I'm hearing about it, despite there being a long standing culture of homebrewing in my country. Does this actually ever happen? Like, was there ever a case of somebody brewing wine and getting methanol poisoning from it? (I'm not talking about adulterated wine, or amounts below toxic levels)

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5028366/

It's totally a thing.

[overseer05-15]

Was flicking through Facebook and a family member (two, really) posted a bunch of comments on a picture of a... presumably negative statistic regarding a political figure of the party I support.

Decided on a whim to check the comments. Evidently political discourse doesn’t involve discussing the veracity of said statistic, how it relates to them somehow compromising their politics, or even how it fares compared to other politicians of various stripes, but saying the person in question needs to brush their hair.

“I agree with them I them on the economy, on education, on welfare and healthcare. I’d vote for them, if only they didn’t look like they were fired through a hedge backwards.”

This some Fahrenheit 451 level shit