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Andy PhD DABT, Toxicologist
Category: Health
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Experience:  Board certified with 20 years in research or consulting
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I don't know if this is the right category but I was

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I don't know if this is the right category but I was wondering how would I go about analysing a sample of chocolate suspected of containing cocaine?
It has been suggested that I should dissolve/slurry the chocolate in water, add NaOH to pH=10 to make sure the alkaloids in cocaine are in base form. Add diethyl ether to the mixture to extract the alkaloid and then subject the organic layer to GC/MS to detect and quantify the cocaine.
Does anyone have any thoughts on this, or extra detail. I mean if I was given a sample of chocolate to analyse how would I first determine that there was cocaine in it? I was thinking XRD or raman etc, or can I go straight into GC/MS?
Also how would I go about determining the purity of the cocaine?


My name is ***** ***** I am the Moderator for this topic. I have emailed a Toxicologist who I believe will be able to assist you. Thank you for your continued patience as we wait for Andy_PhD_DABT to come online.

Camille - moderator

I am sorry, I don't have enough time to give you a definitive answer right now, but could tomorrow. The quick answer is that I do think that would extract the cocaine, but I have to check on it to be sure. GC/MS is the gold standard for detecting it in the extract, so I would use that. By Raman I assume you mean the detector on the gas chromatography, is that what you mean? If so I do thing that would work. There are Raman detectors that can "look" at the surface of the chocolate, but it would pick up all the other chemicals in the chocolate, so that would not work.
I'm sorry for the short response, but I have to go offline until tomorrow.
Take care,
Customer: replied 4 years ago.

(Thanks Camille!)

Hi Andy thank you for your reply, this is extremely helpful. If you do have time to write some more that would be much appreciated.

By Raman I meant analysing the sample as a whole to begin with to determine what is actually inside the chocolate rather than going ahead and extracting cocaine if it turned out not to be.

Thank you


Hi Beth,
Thank you for your patience. Sorry about the delay, but I only work at JustAnswer part time and I had a deadline a make for my other job.
So in theory you could use NaOH to get the cocaine into the free base form from a water slurry. One problem with that is that at high pH cocaine can hydrolyze to benzoylecogonine. That might not be a total loss since you could look for benzoylecogonine, which should not be in chocolate and just add that to what ever cocaine you find. However, a better way is to dissolve the chocolate in a dilute sulfuric acid solution, which would convert free base to the hydrochloride, which would be soluble in the water solution. Then you add ammonia which will change the dissolved cocaine hydrochloride into the free base, which is less soluble in water, making it precipitate out of solution. Since it precipitates out of solution hydrolysis at the higher pH should not occur that much. The precipitated free base is then dissolved in diethyl ether and to clean it up some more, hydrochloric acid is added to the diethyl ether solution to convert the cocaine back to the hydrochloric acid, which is not soluble in diethyl ether and will precipitate. The precipitate can then be run through the GC/MS. The GC/MS is the gold standard and it will be able to identify cocaine from the various other chemicals that may be in the chocolate extract.
Now you really can't tell how pure the cocaine was since it's been mixed with the chocolate and is now very un-pure with a chocolate contaminant. You could however look for "cutting" agents that were in the cocaine sample, but you would have to know what you are looking for. You could try comparing a sample of the same lot of chocolate with the one containing cocaine, but if the cocaine were cut with something like sugar that would be in the chocolate anyway, you would not be able to detect that. Now you can tell how much cocaine is in your chocolate, i.e. how pure the cocaine is as it sits in the chocolate. You start by knowing how much of a chocolate sample you started your extract with then analyze several sample of a known concentration of cocaine on the GC/MS and make a graph of the amount in each of the "known" samples with the output reading for the GC/MS, this is a calibration curve. Then when you run your unknown sample, you compare the GC/MS output with that on the calibration curve you just created and use that to determine the amount of cocaine in your sample, then divide that by the size of your sample. Now really to do it correctly you have to know how efficient your extraction process is, i.e. how much cocaine was lost during the extraction. To do that you would have to take regular chocolate then add a known amount of cocaine to it and do the extraction and run it on the GC/MS and see how much cocaine didn't make it to the end of the extraction (how much didn't precipitate at each step). If you do all that then you can tell very accurately how much cocaine was in the chocolate.
As to your last question, hand held raman devices would be able to measure the cocaine in the chocolate just by shooting the laser at a solid piece of chocolate. However, the problem is that it also will read all the other organic chemicals in the chocolate. Since there are many different chemicals in chocolate, several with somewhat similar structures to cocaine, I think there would be way too much noise in the raman spectrum to be able to pick out cocaine from the other chemicals. Raman hand held devices are great for identifying relatively pure chemicals. In hazmat, we use them to identify an unknown chemical in a spill, which is usually at an industrial site or shipping container where pure chemicals are kept or shipped separably, so are usually pretty pure. In that case a raman works great, but when you have lots of other chemicals in the mix, you really need to do an extraction and some type of chromotography to further separate out the chemicals. The raman can handle some simple mixtures of maybe a few different chemicals, but the more chemicals you have and the more closely those chemicals resemble the one you are looking for the less likely you are able to separate out the cocaine from what ever else is present. The same would go for X-ray diffraction, you need to have pure chemicals for them to be useful. You might be able to use x-ray diffraction on crystals of pure cocaine, such as crack cocaine, but it would not work on a piece of chocolate with a small amount of cocaine in it.
I hope this helps, if you need me to clarify anything, please ask.
Take care,
Andy PhD DABT, Toxicologist
Category: Health
Satisfied Customers: 137
Experience: Board certified with 20 years in research or consulting
Andy PhD DABT and 2 other Health Specialists are ready to help you
Customer: replied 4 years ago.

Fantastic, thank you so much Andy, this has been incredibly helpful!

Your Welcome Beth, glad I could help.
Take care,