How to weigh one-eighth of a gram of Phenidone?

[Keith Tapscott.]

If a film developer formula you wanted to scratch-mix required 0.125 gram of Phenidone per liter of stock solution, how would it be able to be weighed with good accuracy?

 

[Brook]

Gun powder scale, weigh in grains. Check with reloading shops, mine was only about 25$

 

[donbga]

If a film developer formula you wanted to scratch-mix required 0.125 gram of Phenidone per liter of stock solution, how would it be able to be weighed with good accuracy?

Make a percentage solution in isopropyl alcohol and then add an appropriate amount (volume) of the phenidone solution that equals the 0.125 gram weight.

 

[Roger Hicks]

Gun powder scale, weigh in grains. Check with reloading shops, mine was only about 25$

0.125g is (unless I have my calculations wrong) 1.93 grains. This is pretty much the limit of my analytical balance so I'd be surprised if a loading scale could do it. I second Dongba.

Cheers,

R

 

[Blighty]

I was considrering using percentage solutions myself but do developing agents (in particular phenidone) oxidise more quickly in solution and, if so, is there any way of retarding this process? Thanks, Blights.

 

[Roger Hicks]

I was considrering using percentage solutions myself but do developing agents (in particular phenidone) oxidise more quickly in solution and, if so, is there any way of retarding this process? Thanks, Blights.

Yes, they do go off faster in aqueous solution -- partly because the problem with pyrazolidones especially is hydrolysis as well as oxidation. Hence the suggestion to use a non-aqueous solution such as isopropyl alcohol.

I have never done this myself and will leave it to those who have to give more information, but the right solvent should allow storage for months or even years.

Cheers,

R.

 

[Keith Tapscott.]

Thanks for the replies, as Phenidone is difficult to weigh, I was wondering if anyone in the UK sell it already dissolved in a liquid concentrate or how I can do this myself? e.g. A gram in 100ml of a solution that can also help to preserve the Phenidone.
Cheers,
Keith.

 

[Keith Tapscott.]

Yes, they do go off faster in aqueous solution -- partly because the problem with pyrazolidones especially is hydrolysis as well as oxidation. Hence the suggestion to use a non-aqueous solution such as isopropyl alcohol.

I have never done this myself and will leave it to those who have to give more information, but the right solvent should allow storage for months or even years.

Cheers,

R.

I must have missed this reply while typing my own and we passed each other like Ships in the night.
Is Isopropyl alcohol a good preservative of Phenidone? Also, would it be worth considering "Dimezone-S" over "Phenidone `A`"?

 

[Roger Hicks]

I must have missed this reply while typing my own and we passed each other like Ships in the night.
Is Isopropyl alcohol a good preservative of Phenidone? Also, would it be worth considering "Dimezone-S" over "Phenidone `A`"?

Dear Keith,

Surprised me too. I believe that Dimezone-S is a good deal more resistant to hydrolysis than Phenidone-A, but I am at the limits of my knowledge here. Nor am I sure which solvents are best. Sorry I can't help more.

Cheers,

R.

 

[gainer]

Propylene glycol is safe, effective and easily obtained. You could use glycerine aas well, but it is more viscous. If you are just starting to mix your own soups, you may not have seen the recipes that call for propylene glycol as a solvent for long term storage of concentrated stock solutions. I buy mine by the gallon from www.chemistrystore.com at about $16 US + shipping. Roger knows where to get it, I'm sure. I think cattlemen use it as a feed supplement. It is handy stuff to have around. Meanwhile, a few ounces of glycerine from whatevef you call the drug store there will do you. If you keep it lukewarm it will not be too hard to pour.

In my experience, the alcohols are not so good as the glycols for the storage of phenidone. The best of them I have found is 91% isopropanol.

FYI, propylene glycol is 1,2 dihydroxy propane and glycerine is 1,2,3 trihydroxy propane.

 

[Moopheus]

One of these http://www.myweigh.com/pocketscales_mx50.html would probably do the trick. I use a My Weigh scale in my kitchen all the time; they're pretty good.

 

[Keith Tapscott.]

One of these http://www.myweigh.com/pocketscales_mx50.html would probably do the trick. I use a My Weigh scale in my kitchen all the time; they're pretty good.

Hello Moopheus,
I already have scales that weigh in 0.1 gram increments but not intermediate of these hence my interest in dissolving Phenidone in a liquid percentage solution for easier to obtain accuracy. Perhaps the stuff that Gainer suggested. Geoffrey Crawley suggest weighing 0.5 gram of Phenidone and forming a square with it on a sheet of stiff paper, then splitting it diagonally for 0.25 gram and then half again for 0.125 gram. I'm not sure of the accuracy of this although it may be accurate enough for my needs.
Thanks.

 

[Gim]

Propylene glycol is safe, effective and easily obtained. You could use glycerine aas well, but it is more viscous. If you are just starting to mix your own soups, you may not have seen the recipes that call for propylene glycol as a solvent for long term storage of concentrated stock solutions. I buy mine by the gallon from www.chemistrystore.com at about $16 US + shipping. Roger knows where to get it, I'm sure. I think cattlemen use it as a feed supplement. It is handy stuff to have around. Meanwhile, a few ounces of glycerine from whatevef you call the drug store there will do you. If you keep it lukewarm it will not be too hard to pour."

I tried a 10% solution, phenidone and propylene glycol (from chemistry store), 30g/300ml. Phenidone was new and worked in pyrocat hd fine. Used a new brown bottle rinsed with hot water and dried. Mixed it at 140F, topped off with cooler propylene. Everything looked good but two days later I looked at in in my darkroom and it had turned to a crystalized sludge. Does anybody know what might have happened? If its a temperature things it may save others some materials if they know about it.
Thanks, Jim

 

[Antje]

That might very well be a temperature thing. Have you tried reheating it? Maybe you are able to gently heat the stock solution, redissolve the stuff and then make the desired dilution. That should not crystallize, then.

I have seen that a lot in the lab. Solutions that looked fine at 30°C turned into ugly sludge in the fridge and returned to their pristine shape after a bath in 30°C.

Antje

 

[Gim]

Antje
The coldest it gets in my darkroom is 55F when not in use. I have been thinking about warming it up but I wanted to keep it in a 10% dilution as I won't be needing it for quite a while. I will have to play with it and test it before I make any bigger batches of anything. I glad you answered. It helps confirm my suspicion that it may temperature related.
Thanks,
Jim

 

[donbga]

Is Isopropyl alcohol a good preservative of Phenidone? Also, would it be worth considering "Dimezone-S" over "Phenidone `A`"?

No.

Simply make a solution to use for obtaining the amount to be added to whatever you are adding it to. Then throw the remaining solution away; it will go bad fairly quickly.

I don't know the difference in Dimezone-S and Phenidone-A. I think you are trying to pinch pennies in the wrong place. Just purchase an ounce of phenidone - it will kast years in dry form. Phenidone is very difficult to dissolve in water.

 

[gainer]

Propylene glycol is safe, effective and easily obtained. You could use glycerine aas well, but it is more viscous. If you are just starting to mix your own soups, you may not have seen the recipes that call for propylene glycol as a solvent for long term storage of concentrated stock solutions. I buy mine by the gallon from www.chemistrystore.com at about $16 US + shipping. Roger knows where to get it, I'm sure. I think cattlemen use it as a feed supplement. It is handy stuff to have around. Meanwhile, a few ounces of glycerine from whatevef you call the drug store there will do you. If you keep it lukewarm it will not be too hard to pour."

I tried a 10% solution, phenidone and propylene glycol (from chemistry store), 30g/300ml. Phenidone was new and worked in pyrocat hd fine. Used a new brown bottle rinsed with hot water and dried. Mixed it at 140F, topped off with cooler propylene. Everything looked good but two days later I looked at in in my darkroom and it had turned to a crystalized sludge. Does anybody know what might have happened? If its a temperature things it may save others some materials if they know about it.
Thanks, Jim

10% is a bit too much. It means that to measure .125 grams you still must measure 1.25 ml, and if you're after accuracy, that requires a pipette with fine gradations. I usually make a 1% solurion. It's easy enough to weight 1 grams into enough solvent to make 100 ml, and then an error of .25 ml is probably acceptable for most uses. Another way to do it is to make a bigger batch of whatever your making.

Phenidone powder is usually quite uniform in density, so that if you weigh a level teaspoon or tablespoon, you can depend on the smaller spoons to give you the corresponding weight with acceptable accuracy. That is, 1/8 teaspoon will be about 1/8 gram if 1 teaspoon weighs 1 gram. IIRC, that is about what it is.

 

[dancqu]

If a film developer formula you wanted to
scratch-mix required 0.125 gram of Phenidone
per liter of stock solution, how would it be able
to be weighed with good accuracy?

I maintain 1% accuracy in weighing. My Acculab
Scale has 0.01 gram accuracy and resolution.
So 1 gram is the least amount weighed.

Patrick Dignan, who did a lot to popularize phenidone,
recommends a solution of it with sodium bisulfite. I had
the slightest amount left un-dissolved after mixing 1 gram
with 5 grams of bisulfite in 250ml of distilled H2O.

Next time I'll fudge my standard and use 0.96 grams. Dan

 

[Tom Hoskinson]

10% is a bit too much. It means that to measure .125 grams you still must measure 1.25 ml, and if you're after accuracy, that requires a pipette with fine gradations. I usually make a 1% solurion. It's easy enough to weight 1 grams into enough solvent to make 100 ml, and then an error of .25 ml is probably acceptable for most uses. Another way to do it is to make a bigger batch of whatever your making.

Phenidone powder is usually quite uniform in density, so that if you weigh a level teaspoon or tablespoon, you can depend on the smaller spoons to give you the corresponding weight with acceptable accuracy. That is, 1/8 teaspoon will be about 1/8 gram if 1 teaspoon weighs 1 gram. IIRC, that is about what it is.

Yes, my Phenidone stock solution is made up of 1 gram of Phenidone dissolved in sufficient propylene glycol to make a total solution volume of 100ml. It's been stable for 3 years - and counting.

 

[Brook]

I checked my scale, it has increments of 1/10 of a grain, it has worked fine for tiny amounts of phenidone. People who reload ammunition need this kind of precision. It was made by Lee.

 

[Gim]

Absolutely, to use a small amount of phenidone make a 1% solution. It was mentioned that proplyene glycol is used as a long term storage of concentrated stock solutions. I just brought this up as you may want to watch the temperatures so you don't have the same problem I did. (If temps are the problem). I have catechol and phenidone mix in solution with no problem. Good stuff.
Jim

 

[walter23]

You should be able to find a small electronic scale in a pawn shop. Some kinds of people use them to measure other kinds of chemicals for sale and pawn shops always seem to have a number of them.

 

[Roger Hicks]

I checked my scale, it has increments of 1/10 of a grain, it has worked fine for tiny amounts of phenidone. People who reload ammunition need this kind of precision. It was made by Lee.

Thanks; fascinating. I wonder how they can do this kind of precision for $25. Economies of scale, I guess. Is it a beam balance? Electronic? Or what?

Cheers,

R.

 

[Tom Hoskinson]

These small electronic scales are typically based on a strain gage load cell.
A load cell is a transducer which converts force into a measurable electrical output. Although there are many varieties of load cells, strain gage based load cells are the most commonly used type.

However, these electronic scales are quite sensitive to temperature changes and air currents - best to use them in a controlled (shielded) environment if you require a high degree of accuracy and repeatability.

Still, the easiest and most practical method to measure out fractions of a gram is to make up a percent solution.

 

[gainer]

Thanks; fascinating. I wonder how they can do this kind of precision for $25. Economies of scale, I guess. Is it a beam balance? Electronic? Or what?

Cheers,

R.

Economies of scale? Was that an intentional pun?

I got a powder scale from a local sporting goods shop that was a beam balance and was sensitive to 0.1 grains. These are also available with Metric scales, but may have to be specially ordered in the US. Most of the parts are of plastic except for the beam itself and the attached scale which carries the slider. It was fine for the small weights. My grandson has perverted it to use for measuring gunpowder. Or should I have said unperverted it?