Quercetin Chalcone develops like Pyrogallol

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Alan Johnson

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These are related experiments but in the one paper the pH is 5.2, in another the composition of the extract and pH are not given and in another there is no mention of catechol.
The right conditions for caffenol developer are much more closely defined.
 

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Most of the research in catechol variants plus Ascorbic Acid are focused on food stuff, therefore it does not surprise me to see neutral to acidic pH numbers in these papers. Some things are maintained across pH (e.g. the redox potential difference between Catechol and Ascorbic Acid), but others may change a lot.
 

relistan

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Thanks guys. I’m really not looking to find a paper that proves anything, since I don’t think that’s going to happen. I’m trying to understand what might be happening and to build some kind of understanding I can use to reason about it. We (or at least I) can then have a framework to scope the realm of experiments that make sense to try. Even after some experiments we might still only know that something works or not, but not why. But maybe we learn both.
 

relistan

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Yes, and the same focus seems to have, for example, limited the solvents that have been tested for Quercetin solubility as well. Everyone of course wants a food-safe solution whereas our requirements are more flexible.
 
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Alan Johnson

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Caffenol-C-M, recipe

Hi there, so lets start the show with my basic recipe and some words about the ingredients. You already know that Caffenol-C is made of i...
caffenol.blogspot.com
I developed Kentmere Pan 400 film 20min 20C in the Caffenol CM formula leaving out the coffee but with other additives.
The pH of Caffenol CM with coffee was measured as 9.8.
Additives and the resultant pH were Ascorbic acid 16g/L pH 10.3, Catechol 4g/L pH [adjusted with bicarbonate] 10.4, Catechol 4g/L + Ascorbic Acid 16 g/L pH 10.3
pH with additives was about 0.5 units higher than Caffenol CM as no attempt was made to adjust for the acidic missing coffee.

Results are shown in the attachment.
There is weak development and some fog with ascorbic acid additive alone at pH 10.3, somewhat more density with catechol alone [no fog] and a definite increase in density with catechol plus ascorbic acid together.
The results are consistent with catechol being regenerated by ascorbate [superadditivity]
 

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relistan

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Very interesting Alan. Thank you for this experiment! That continues to support this line of thinking.

Fog level in the versions with ascorbic acid is even higher than I remember from caffenol. I wonder if the 0.5 pH difference has that effect. Or maybe something else in coffee is a mild restrainer.

Interestingly, I found today that Jay DeFehr made a developer based around these two agents back in 2006 called Hypercat. He didn’t believe they were superadditive, per his description (see comments on post) http://hypercatacutancedeveloper.blogspot.com/2006/12/introduction.html?m=1

However, it may be that there is something to the concentration of ascorbic acid that changes the relationship, possibly related to the earlier article where it claims that a 1.5% solution of ascorbic acid changed the relationship to the catechol.

The best link I can find to the formula is here: https://www.digitaltruth.com/data/formula.php?FormulaID=162 . There is only 0.5g of ascorbic acid. So it may just be that the amount was so small the effect was not detectable.
 
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Alan Johnson

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Yes, sometimes people claim a food extract will develop film without checking that it's not the ascorbate.
I said results " are consistent with" regeneration of catechol by ascorbate.
To actually prove it would be a postgrad project in an Electrochemistry Lab IMO.
 
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Rudeofus

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relistan said:
Fog level in the versions with ascorbic acid is even higher than I remember from caffenol. I wonder if the 0.5 pH difference has that effect. Or maybe something else in coffee is a mild restrainer.
Click to expand...

The different pH most definitely has an effect, but let's also not forget, that the 4 g/l Catechol in Alan's developer is much, much more than what you have in Caffenol.

relistan said:
The best link I can find to the formula is here: https://www.digitaltruth.com/data/formula.php?FormulaID=162 . There is only 0.5g of ascorbic acid. So it may just be that the amount was so small the effect was not detectable.
Click to expand...
Strangely the formula in digitaltruth lists only half the Ascorbic Acid from what Jay posted in his own blog. If you then dilute the stock solution as instructed on digitaltruth, you get an Ascorbic Acid concentration of 5 mg/l, which will not be enough to restore much Catechol.
 

relistan

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Weird, having even posted that link to his blog I had looked around and not managed to find the formula. Thanks for finding that. Once again showing what a risk it is copying formulas from somewhere that isn't the source. Thanks
 
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relistan

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My quercetin tablets arrived today! It being Saturday, after I was done with the domestic agenda in the morning, I had time to try an experiment.

I had two things I wanted to test:
  1. On a hunch, I thought I'd like to see if triethanolamine would improve solubility of quercetin
  2. Can we show any superadditivity between ascorbic acid and quercetin itself?
This is the setup:
  1. Got 1 500mg quercetin tablet from the jar. This contains a few things that are not quercetin. I will post below.
  2. Crushed it as much as humanly possible with a dedicated pill crusher (these are cheap!)
  3. Mixed it with 2ml of triethanolamine into a British mustard-like consistency and color
  4. Added to 100ml of tap water
  5. Did not filter, just stirred once a minute to keep in suspension
Since I have gotten my new pH meter but not yet calibrated it, I tested pH with paper. Starting pH of the above was high 9s, ~9.7-9.8 guessing from previous experience.

I then ran a few tests for 10 minutes each, at 68F, using snippets of that old Fomapan 400, my perennial test dummy:
  • Quercetin alone
  • Quercetin with 1.6g of ascorbic acid, pH about 8.8
  • Quercetin with 1.6g ascorbic acid, pH matched back to the high 9s with paper (more info below)
Some interesting observations:
  • The quercetin (or other pill components) does not all dissolve, not even close
  • At higher pH it seems to stay in suspension better than at lower pH
A few caveats:
  1. I had a heck of a time getting the pH back up to high 9s once the ascorbic acid was added. I added a lot of sodium carbonate and then gave up and added some more TEA since my carbonate is old and may have become bicarbonate. This means that if TEA does improve solubility of quercetin in water, then this experiment does not entirely show the possible superadditive properties of the two agents, because the latter test contains more TEA.
  2. There might be something in the pill that is affecting development
  3. I did not test ascorbic acid by itself in the same configuration
That being said, the pill ingredients are:
  • Quercetin dihydrate
  • Calcium carbonate
  • Cellullose
  • Anti-caking agents:
    • Stearic acid
    • Silicon dioxide
    • Magnesium stearate
  • Pill coating:
    • Hydroxypropyl methylcellulose
    • Glycerin
The results:

The quercetin alone does develop film, but not very well. Quercetin and ascorbic acid together appear to be a strong developer. Since I think the only main difference from @Alan Johnson 's earlier testing is that there is more ascorbic acid, I can only presume this is why it works faster. I am not certain if the streaking on the darkest test strip is from sediment settling on it and increasing the concentration, or something that may have happened to this clip of film sitting in my box.

All tests are fixed with Ilford Rapid Fixer, which is acidic and may eliminate stain.

Densities:
  • Fixed Fomapan 400, no development: 0.34
  • Quercetin alone: 0.61
  • Quercetin with 1.6g of ascorbic acid, pH about 8.8: 0.65
  • Quercetin with 1.6g ascorbic acid, pH matched back to the high 9s: 1.25 (!)
I'm attaching some photos of the setup and the results on the light table. Since these are not real photos, it's hard to say anything about fog conditions.

Last photo is Fomapan fixed without any dev, quercetin alone, querceting with 1.6g ascorbic acid and pH matched


 
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Alan Johnson

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The content of polyphenols in coffee beans as roasting, origin and storage effect - European Food Research and Technology

Coffee, one of the most popular beverages in the world, contains many bioactive compounds. The aim of this study was a comparative evaluation of the content of bioactive compounds in organic and conventional coffee (Coffea arabica) originating from Brazil during 12 months storage. The content of...
link.springer.com
From the table 100g coffee contains at most 0.0062+0.0103+0.011 = 0.0275g quercetin compounds or 0.011g to make 40g in Caffenol CM for 1L caffenol.
If I got the decimal point right and noting from the table that its concentration in coffee falls off with storage, it seems that quercetin would not be a significant contributor to coffee developing activity?
 

relistan

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I don’t know Alan, you can probably better say than me. The only data point I have is that I know from carryover experiments with my two baths that .01g of phenidone with 0.24g of ascorbic acid will happily develop film at this pH.

EDIT: relevant conversation here https://www.photrio.com/forum/threads/advice-on-my-two-bath-developer.181701/page-6#post-2420806
 
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relistan

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Also @Alan Johnson I think we talked about this before on one of the threads. Chromogenic Chlorogenic acid, which you pointed out is present in much larger quantities in caffenol also has a catechol moiety and may behave quite similarly to quercetin. It's much harder to get though and from that standpoint seems less useful to the hobbyist as a practical matter, even if it does behave similarly (which we don't know).

EDIT: Alan correctly pointed out below that I accidentally typed the wrong acid name.
 
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Alan Johnson

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The content of polyphenols in coffee beans as roasting, origin and storage effect - European Food Research and Technology

Coffee, one of the most popular beverages in the world, contains many bioactive compounds. The aim of this study was a comparative evaluation of the content of bioactive compounds in organic and conventional coffee (Coffea arabica) originating from Brazil during 12 months storage. The content of...
link.springer.com
Yes, agree with your comment. Unlikely that anyone would try chlorogenic acid because of the cost.
 

relistan

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I got the time this morning to finish things off with a test in the same setup, with ascorbic acid alone. The results show more density than simple additivity would indicate

Adding 0.07 + 0.27 and comparing to 0.909,( densities minus base density) we can see quite a bit more density built by the two together.

Together they seem to have the potential to be an OK developer—at least from a density-building standpoint, which is only one small aspect.
 
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relistan

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I was thinking about what we found here and there are a few directions this could take. Some might not make sense on this thread. Things I'm interested in from here, and that I think you guys are maybe interested in also:
  1. Can we formulate a catechol-like developer with quercetin and ascorbic acid that is useful? Prices are now within reason for quercetin, especially in the UK. @Alan Johnson demonstrated that you can get good results with quercetin earlier on this thread.
  2. What are the implications for tuning and/or improving caffenol based on what we learned? Some of these things, as @Rudeofus pointed out to me, may not be of interest to much of the caffenol crowd, but could lead to a pretty interesting "real" developer in the sense that it's not a magic black box.
  3. Are there implications for a further actual catechol/ascorbic acid developer along the lines of Alan's work on this thread?
One interesting thing that occurred to me is that some of the different results that people get from caffenol are probably pH-related. Given that it appears that somewhere between pH 9.8 and 10.5 ascorbic acid becomes more active directly (Alan's testing), fog and development time may be noticeably affected by pH.

It would be interesting to do more testing around the 1.5% ascorbic acid concentration idea for the relationship between catechol/quercetin and ascorbic acid. One very striking thing to me is that the development times for Caffenol-C-M and Caffenol-C-L are hugely different—15 mins vs 70 mins stand. The main difference are pH and ascorbic acid content. My thinking is that if there is something to the 1.5% idea mentioned in that paper about browning fruits/vegetables that is relevant to film development, then actually it might be that drastically less ascorbic acid in Caffenol-C-L might produce the same result. But this is probably most easily tested for with either real catechol, or with quercetin, to eliminate other variables.

I personally am interested in messing with quercetin more now that I have about €25 invested in a bottle of tablets! Also, given that solubility of it is so low, 60 tablets may actually make a LOT of developer.
 

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relistan

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I’ve made up the following solution and will let it sit for a day to see what settles out.

  • 150ml water at 40C
  • 2ml triethanolamine
  • 500mg tablet of quercetin crushed to a very fine powder
I mixed as before, quercetin in 2ml TEA as mustard consistency. Then added to the water. It’s in a little IKEA bottle.

 

relistan

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19 hours later it is clearly oxidizing, despite the top of the bottle being filled with canned air.

I found a paper that appears to document the likely oxidation products at this pH at ambient temperatures in aqueous solution. The ultimate product appears to be protocatechuic acid, which retains the catechol moiety. However, the NIST paper on reduction potentials indicates that it is a much worse reducing agent than quercetin.

I will do a test later today and compare to my previous results.

 

relistan

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Alan Johnson said:
See post 30, even at pH~11.6 development took 2hrs. Your yellow mix will have pH ~9.
Click to expand...

Thanks Alan. Yes, my plan was to test it always with ascorbic acid since I don't think it makes sense as a developer by itself from your testing, even un-oxidized. So I tested it today with ascorbic acid again and without it, for fixed times. I wanted to understand if this color change reflected anything important about how well it works. pH from my paper was high 9s. Dark green, with just a hint of blue. This is what I got.

Today I did the following experiment for (A) Quercetin by itself, (B) Quercetin with ascorbic acid, matching process from previous run:
  1. Started 24 hours after I bottled yesterday
  2. Carefully decanted 20ml of the brown liquid from the top of bottle into a shot glass that I use for testing
  3. Developed for 10 mins @20C
In the second round I added slightly over 0.3g of ascorbic acid, targeting the equivalent of 16g/L.

Results
  1. Surprisingly, I did not observe a change in activity. This may be because quercetin is so insoluble that when it converts to protocatechuic acid or one of the other oxidation products, that this allows some of the reservoir on the bottom of the bottle to dissolve along with it.
  2. Densities were as follows on Fomapan 400:
    1. Browned quercetin by itself: 0.53
    2. Browned quercetin + ascorbic acid: 1.28
    3. I did not re-test ascorbic acid alone since we already have values for this
These are darn close to the same values I got from the previous testing with all the sediment in the solution and the solution being completely yellow. The differences I think are probably down to process control (temp especially) being hard on such small samples and without having calibrated and set up my pH meter.

Observations

When adding the ascorbic acid, a bunch of the quercetin and oxidation products come out of solution. Bumping the pH back up and stirring brings them right back into solution.

Conclusion

It seems that the browned solution is quite viable after 24 hours and is either still largely active quercetin, or the oxidation products are equally active in tandem with ascorbic acid. Or the browning does not signify oxidation.

Probably we are testing a saturated solution in both cases and it's far less than 500mg.
 
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relistan

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I tested some shots out in a basic quercetin developer to see how it might look. Due to a series of errors, the results are not scientifically useful. But I thought I'd post an image from the test because I think it indicates that it's worth continuing to try to make something useful here (as @Alan Johnson also showed earlier in this thread).

I have no idea why this is so scratched to heck. I think there was something wrong with the film canister or from bulk loading a long time ago, this is not a result of development. The rest of the roll was not like this but this is the best frame for exposure.

Ignore the scratching, it's the grain and gradation that look interesting to me. This is Fomapan 400 in my Yashica Electro 35 GSN. Finer grain that I normally expect from Fomapan 400. It is thin, and that will make grain look better. But I have other negatives from other tests that are this thin and it looks a little better than those.



This was the formula I tested here:
  • 100ml solution from the IKEA bottle
  • 200ml warm water
  • 5.3g ascorbic acid
  • 7g sodium sulfite
  • 6ml TEA
  • Sodium hydroxide to pH 9
  • Temp back to 20C for development
This was dumb, because it ended up with not enough quercetin in solution. You really need to have a saturated solution. The pH is also too low. It should be 9.7-9.8 for best results I think. I also then developed it for too short a time as a result. 16 mins @ 20C. Not even close to long enough for a non-saturated solution. I think it is long enough for a correct concentration and pH, based on earlier testing of strips of film. There is no fog. No fog at all. Base density measures more or less the same as undeveloped/fixed film.
 
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