Alkaline Acid? What The Heck?!

Snapshot · Dec 29, 2007

Hi All,

I was mixing up some PC-TEA the other day and processed a roll of APX 100 today using this newly mixed batch. The PC-TEA was used at 1+50 dilution for 9:00 minutes at 68F. Agitation was for the first 30 seconds and 10 seconds each minute thereafter. After processing and fixing, the negatives came out dense and obviously overdeveloped.

Wondering what the issue could be, I diluted some PC-TEA and took a pH reading. It was well above what I was expecting, around 10.1 pH at 1+50 dilution. I tested solutions of the various chemistry used and found that the ascorbic acid solution was highly alkaline. The pH was over 8.9 on my pH meter. This was freshly order from JD Photochem and was not opened before. Obviously, the ascorbic acid is contaminated but with what? :confused:

Anyone know have any clue as to what could have contaminated the chemical? Is it likely a manufacturing issue? Probably unknowable as it could have been adulterated at any point up until it arrived at my home. Just wondering because, aside from the faster processing times, it appears that PC-TEA is working fine without much difference in grain. Not a totally undesirable side-effect and something I may attempt to repeat in the future.

Photo Engineer · Dec 29, 2007

Well, ascorbic acid can be contaminated with sodium ascorbate which renders it more alkaline than pure ascorbic acid.

TEA can be contaminated with DEA which not only has a different alkalinity, but a different effect on emulsions than TEA.

I would guess that someone may have actually packed sodium ascorbate rather than ascorbic acid.

PE

Snapshot · Dec 29, 2007

Well, that would account for the ascorbic acid solution being alkaline. The TEA seems to be at about the right pH for TEA. Nonetheless, the formula seems to be working otherwise, other than the fact it's faster.

Thanks PE.

Snapshot · Dec 29, 2007

As a follow-up, I redid the pH test with the "ascorbic acid" by creating a simple solution with it. This time, I used spring water (with a pH of 7.3) instead of my regular tap water, as mine has a pH of about 7.7 or so. Well, the solution had a pH of about 8.3, which means it's not ascorbic acid or not very pure if it is. Foolishly, I 'test tasted' a very tiny amount and it had very little tang to it and slightly salty flavour.

In retrospect, I should have realized I wasn't working with ascorbic acid as this chemical had a very hard time dissolving in the TEA. In fact, it took 3 heating sessions and an entire night of sitting before it mostly dissolved. As per PE's guess, I believe it's sodium ascorbate. The solution works and I've developed film with it (at a faster rate to boot), so I can live with the result.

Photo Engineer · Dec 29, 2007

Yes, well Sodium Cyanide is alkaline and slightly bitter sweet in taste, but it would be your last taste test if that were the case. Anyhow, it is a silver halide solvent and fogging agent, so I was just kidding here. Please be careful!

Ascorbic acid should be sharp and sour tasting. Sodium ascorbate can be bitter. But my advice is to never test unknowns. Too much risk involved.

How do you feel?

PE

Photo Engineer · Dec 29, 2007

As an addendum, I would contact your supplier and report this problem.

PE

Snapshot · Dec 29, 2007

I feel fine, and you're right, I should not have tasted it. I guess I wanted to confirm that it was or wasn't ascorbic acid and I know vitamin-C has quite a 'sharp bite' to it. I'll e-mail Claire at JD Photochem and let her know. Thanks again PE.

DarkroomExperimente · Dec 29, 2007

Photo Engineer said:
Yes, well Sodium Cyanide is alkaline and slightly bitter sweet in taste, but it would be your last taste test if that were the case. Anyhow, it is a silver halide solvent and fogging agent, so I was just kidding here. Please be careful!

Ascorbic acid should be sharp and sour tasting. Sodium ascorbate can be bitter. But my advice is to never test unknowns. Too much risk involved.

How do you feel?

PE

reminds me of this quote from CRC's Handbook of Chemistry and Physics:

"Beryllium and its compounds should not be tasted to verify the sweetish nature of Beryllium ( as did early experimenters )."

I always thought that was rather ominous...they never mention what happened to those "early experimenters"

Photo Engineer · Dec 29, 2007

Fischer, one of the early experimenters in synthetic organic chemistry often tasted his new compounds and reported the taste in his publications in German journals. I guess he lived to a reasonable age for the time. I never really looked into it, but our professors told us of his methods and warned us against them.

PE

DarkroomExperimente · Dec 29, 2007

dunno if this is apocryphal or not...

Arthur Conan Doyle was apparently teaching at a medical school and he told his students the importance of being very observant....he took a beaker of urine, dipped a finger into it...then licked his finger.

He said "I want you all to do exactly what I did"...then he passed the beaker around the room and each student hesitantly dipped a finger into the urine..then licked it.

When the beaker had made it around the room he told them..."I told you to do exactly what I did...and if you had been watching, you would have noticed that I dipped my index finger into the urine, but it was my middle finger that I licked."

Photo Engineer · Dec 29, 2007

That is not only correct, the urine was particularly distasteful having come from someone with a kidney problem. We were taught that in school. Be observant, but don't ever taste the chemistry.

PE

Murray@uptowngallery · Dec 29, 2007

I saw a list once on artificial flavorings, their chemical names and what other uses they have at normal strength (highly diluted for flavoring).

It was kind of disturbing.

I imagine A.C. Doyle's teaching methods also instilled a 'watch your back' mentality in the students.

snallan · Dec 29, 2007

The thing with artificial flavour compounds is, that most of them are simply synthetic versions (ie prepared on an industrial scale) of the chemical compounds found in nature. It may seem disturbing to see the dictionary listing of a flavour compound (BTW was the list from Fenaroli by any chance?), but their presence in natural products is the reason for their flavour/aroma.

Photo Engineer · Dec 29, 2007

Here are a few:

Benzaldehyde = Oil of almonds or cherry flavor
Phenyl Ethyl Alcohol = Oil of roses
Cinnamaldehyde = Cinnamon oil
Ethyl Acetate (and a few other related chemicals mixed) = Banana oil
Limonene = Lemon flavor
Cadaverine = Rotting meat
Putrescene = Rotting meat
Skatole = Odor of excrement
t-Butyl Mercaptan = Skunk oil
Pheny acetic acid = Monkey house at the zoo
t-Buyraldehyde = Dirty sweat socks

There are a few good and bad to remember. The last 6 are toxic.

All odors and flavors are derived from pure or mixed organic chemicals. Most good ones are either aldehydes, alcohols, esters or terpenes. Bad ones are usually amines, acids and mercaptans. I've listed a few of each class.

PE

Snapshot · Dec 29, 2007

Photo Engineer said:
Here are a few:
Limonene = Lemon flavor
Cadaverine = Rotting meat
Putrescene = Rotting meat
Skatole = Odor of excrement

These make a form of 'sense' in terms of their names. I found 'scatole' particularly amusing.

gainer · Dec 29, 2007

Add methyl salicylate as oil of wintergreen. Country folks in my grandfather's time chewed willow twigs for headaches and toothaches. It has a salicylate, but not particularly aromatic.

Photo Engineer · Dec 29, 2007

BTW, just because I mentioned that some of the chemicals listed are flavorings does not mean that I encourage anyone to use any of them. They must be specially purified for use in flavorings/food, and they are used very dilute. Sometimes they are as dilute as 0.1%, so I do not suggest you taste them.

PE

Snapshot · Dec 29, 2007

Photo Engineer said:
BTW, just because I mentioned that some of the chemicals listed are flavorings does not mean that I encourage anyone to use any of them. They must be specially purified for use in flavorings/food, and they are used very dilute. Sometimes they are as dilute as 0.1%, so I do not suggest you taste them.

PE

So, no 'skatole' for my French toast?

Photo Engineer · Dec 29, 2007

Well, you wouldn't want to even go into your kitchen for a while. It would smell pretty bad I guess.

BTW, I tried it once in a fix or a bilx. I can't remember, but I know it didn't work. I remember being GLAD! I've also used histamine in processing solutions. It made everyone in the lab sneeze.

PE

Jordan · Dec 30, 2007

Back to the OP's original question... it sounds like you did indeed get sodium ascorbate instead of ascorbic acid, which would be a pretty big oversight on JD Photochem's part (and I'm surprised, because they're pretty reliable).

There is a test you can carry out to see if you've got sodium ascorbate or some other non-reducing salt. You would need "tincture of iodine" (from the grocery store) and starch to do it. Let me know if you're interested.

walter23 · Dec 30, 2007

Snapshot said:
I feel fine, and you're right, I should not have tasted it. I guess I wanted to confirm that it was or wasn't ascorbic acid and I know vitamin-C has quite a 'sharp bite' to it. I'll e-mail Claire at JD Photochem and let her know. Thanks again PE.

Heh, a better choice would have been to check the calibration of your pH meter or try the test with pH indicator paper.

Snapshot · Dec 30, 2007

walter23 said:
Heh, a better choice would have been to check the calibration of your pH meter or try the test with pH indicator paper.

I did use pH indicator paper to check against the meter. It registered a 9 on the scale, although the paper scale hard to read.

Snapshot · Dec 30, 2007

Jordan said:
Back to the OP's original question... it sounds like you did indeed get sodium ascorbate instead of ascorbic acid, which would be a pretty big oversight on JD Photochem's part (and I'm surprised, because they're pretty reliable).

There is a test you can carry out to see if you've got sodium ascorbate or some other non-reducing salt. You would need "tincture of iodine" (from the grocery store) and starch to do it. Let me know if you're interested.

I'm interested. What would I need to proceed?

walter23 · Dec 31, 2007

That means nothing. Sucrose is (2R,3R,4S,5R,6R)-2-[(2S,3S,4R,5R)-3,4-dihydroxy-2,5-bis(hydroxymethyl)oxolan-2-yl]oxy-6-(hydroxymethyl)oxane-3,4,5-triol.

Chemical nomenclature is just a systematic set of rules for naming molecules, from the mundane (oxidane - water) to the toxic (potassium cyanide). To a lay reader the intimidation-factor of the name means nothing.

Murray@uptowngallery said:
I saw a list once on artificial flavorings, their chemical names and what other uses they have at normal strength (highly diluted for flavoring).

It was kind of disturbing.

I imagine A.C. Doyle's teaching methods also instilled a 'watch your back' mentality in the students.

Jordan · Dec 31, 2007

Snapshot said:
I'm interested. What would I need to proceed?

Sodium ascorbate, and other reducing agents, will reduce iodine (I2) to iodide ion (I-). Iodine itself is coloured, iodide is not -- not only that, iodine makes a strongly coloured complex (deep blue-purple) in the presence of starch. Based on these principles, I'm about 90% sure the following will work:

(1) Make a decently strong solution of starch in water (you'll need to use hot water)

(2) Make some solutions up:

starch solution alone (blank)
starch solution with a few grams of salt in it (negative control)
starch solution with a few grams of plain ascorbic acid (or dissolve a Vitamin C pill) (positive control)
starch solution with a few grams of "mystery powder" in it (test)

(3) Carefully add a drop of tincture of iodine (from the drugstore) to a portion of each of the above solutions (use disposable plastic cups or something), swirl to mix, and view the colour against a white background.

(4) Results:

blank turns deep purple-blue
negative control turns deep purple-blue
positive control becomes colourless (the brown colour of the iodine disappears)
test solution turns deep purple-blue if there is no reducing agent present -- otherwise, if it becomes colourless, there is some kind of reducing agent present

Usually the starch-iodine test is used in the "reverse direction" to test for oxidizing agents but this should work too. Be careful. Don't use containers you'll later want to use for food. If the blank and controls don't work as expected, I messed up Report back to us on how it works!

Alkaline Acid? What The Heck?!

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