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Determening the Purity of Heroin with Limited Resources

S

seep

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Nov 28, 2008
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Pure heroin has a melting point of 243.5 deg C. An electric melting point apparatus and some capillary tubes have been procured, but no other equipment (except a mercury thermometer) is available. A new "brand" of heroin has has hit the streets and 2 grams were procured. A minute portion was placed into the EMP apparatus, and its melting point was observed to be 228-231 degrees. Obviously the heroin is not pure, but the substance used to cut the heroin is unknown (though fully miscible). Is it possible to determine the purity of this brand using simple freezing-point-depression calculations? Every algebraic manipulation of the formulas I've used has more than one variable.
 
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Or if anyone knows pure heroin's heat of fusion, I can consider heroin the solute and subtract the calculated mole fraction from 1. That'll give me the exact concentration of pure heroin in the sample, I think, even if I don't know what the sample's been cut with.

I think?

I think maybe I've mungled up the concepts somehow.
 
Well, if you had a lot of rats, and didn't mind wasting a fair amount of dope, you could emperically determine the LD50, and use that figure to deduce the purity.
 
Unfortunately the experimentors have consumed the remainder of the sample. Further experimentation is contingent upon the dealer answering his fucking cellphone.
 
^^^^^^^^^^^^^
HA!

Also, the rat LD50 idea (if it was not a joke) is probably the most absurd possible suggestion with regards to finding the purity of heroin.

To the OP- is there a way you could possibly separate the the cut from the heroin (maybe simple chromatography with a paper towel), and then find the melting point of the cut? This would allow you to find out what the cut it.
 
Preparative Analytical Thin Layer Chromatrography should give a pretty accurate measurement. It is time consuming but that is about as "limited" as you can get, materials would cost a couple hundred dollars assuming you know the technique.
 
Wow watch The French Connection from 51:59 to 53:45.

daddysgone said:
To the OP- is there a way you could possibly separate the the cut from the heroin (maybe simple chromatography with a paper towel), and then find the melting point of the cut? This would allow you to find out what the cut it.
Click to expand...

=D

The coolest thing about this is that the dude can use copies of the paper strips to market his product. Just slip them right into the 1/2 gram baggies.

Maybe a monograph is forthcoming.

Still though, I have a general interest in the quantitative reliability of the FPD test when only the solvent is known. This is island chemistry, but it doesn't necessarily have to be crude.
 
the mp is a long way from the mp of pure material however when the mp differs by up to 5oC from pure material, the rule of thumb is .5 degree per 1 percent impurity usually works out about right. so 96% would be depressed by 2 degrees, and so on. the rule falls apart below 90% purity

in the olden days the purity of diamorphine was determined by the measuring absorbance of a 0.1% solution in alcohol using a spectrophotometer, now forensic labs use HPLC-UV and all the other more expensive hyphenated techniques. I think the absorbanceof pure diamorphine is in Clarkes' poisons.

there is also a method where the Diamorphine is hydrolysed to morphine and then reacted with nitrite to give a golden solution, the absorbance is recorded at 450nm and the concentration can be determined.
 
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Many thanks.

I'll settle for the spectrophotometer, as I don't know/don't have access to HPLC-UV.
 
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