Measuring small quantities of Phenidone

As most phenidone based developers use less than 1g of phenidone per litre of stock solution often with an accuracy of two decimal places I was wondering if there is any effective way of reasonably accurately measuring the phenidone. I was wondering about dissolving 1g of phenidone in 100ml of propylene glycol and using, for example, 25ml of this solution when the formula calls for 0.25g of phenidone. IIRC propylene glycol should have no noticable effect on the developer - am I correct?

All help much appreciated,

Lachlan

Lachlan Young said:

As most phenidone based developers use less than 1g of phenidone per litre of stock solution often with an accuracy of two decimal places I was wondering if there is any effective way of reasonably accurately measuring the phenidone. I was wondering about dissolving 1g of phenidone in 100ml of propylene glycol and using, for example, 25ml of this solution when the formula calls for 0.25g of phenidone. IIRC propylene glycol should have no noticable effect on the developer - am I correct?

All help much appreciated,

Lachlan

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You are correct, Lachlan. In fact, you've described the method I use.

It's easier to dissolve in 91% isopropyl rubbing alcohol. Requires no heating, and it's easier to come by. Seems to keep forever this way too. I add some potassium metabisulfite to the container on the theory that it should scavenge oxygen and water, but I really don't know if it does anything.

Making a stock solution is a good approach. Another is to buy a scale with 0.01g precision. Inexpensive ones can be had for under $50, but they'll probably top out at 50g or 100g maximum weight. You'd probably want to use a less precise scale with a higher maximum weight for weighing things that are used in greater quantity.

My $20 reloading scale (well, okay, that was 25 years ago, that model is probably around $40 now) will measure to better than 0.1 grain (at 15.4 grains per gram, that's a bit more than six milligrams); I can probably get .01 grain out of it (just over half a milligram) with care and a suitable method of trickling material into the pan, but there's no reason to spend money on an additional high precision scale if you already have a scale -- the stock solution method is the most recommended. Make the solution with a carefully measured ten grams of phenidone in a liter of isopropanol, and you'll have a year's supply or more and need nothing more precise than the same syringe you'd use to measure HC-110 syrup or Rodinal concentrate.