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Brownies anyone?

  • Amanda Rigdon
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I’ve gotten a couple of interesting customer questions regarding the extraction of drugs from food matrices. Mostly I deal with ordinary matrices like blood and urine, so I’ve enjoyed the challenge of recommending an extraction method for a new matrix. Recently, a method known as QuEChERS became popular in the food safety industry for the extraction of pesticides from food. I’ve tried to apply this approach as an alternative to SPE for biological matrices, but it seems that the QuEChERS approach can’t compete with SPE for forensics as it can with the methods used in food safety. I had pretty much reached the conclusion that QuEChERS would remain homeless in forensics until I received an inquiry from a customer on QuEChERS for pot brownies. Since QuEChERS was developed for food, this method seems like it will mesh well with pot brownies, LSD gummy bears, and other interesting samples. Check out the links below for information on QuEChERS, and please contact me if you have any comments.



Fri, May 06, 2011

Hi Jon, Thanks for your comment! From your post, it sounds like you're actually asking two questions: do I have any suggestions for your method of potency testing for leaves, oils, etc. and should you consider using QuEChERS as the extraction method of choice for all your analyses. I have two answers for you: yes, and no. I hope that helps...just kidding. With regards to your potency testing for leaves and such, I think your current extraction method is pretty much okay. It seems like that’s what a lot of people are doing, and it works pretty well. The reason why it works so well is that leaves contain massive amounts of THC and not a whole lot of other stuff. Yes, there are definitely pigments and sugars and other plant compounds (I’m a chemist, not a botanist!), in your leaves, but you can get away with a small sample size because of the level of THC in the sample, thus ‘diluting out’ your interferences. My only suggestion for your method is to use a larger sample and grind the sample prior to extraction. This ensures that you get a homogeneous, representative sample that can be easily extracted. It’s easier to get compounds out of small pieces of things rather than big chunks, right? That being said, feel free to take or leave my suggestions. Moving on to the edibles testing, the reason why this is so much more problematic is that the THC content in products like brownies should be much lower than in leaves and oils because of all the extra stuff there in the edible product – it has to taste good, right? Since I’m a chemist who was pretty lame in college, I don’t know how potent these edibles are, but I’m pretty sure they’re nowhere close to the realm of leaves or oils. Feel free to correct me if I’m wrong! So now, instead of extracting a sample that has massive amounts of THC and not much else, you’re trying to extract something with a small amount of THC and a lot of fat, flour, sugar, and cocoa. This is where QuEChERS really shines. By using QuEChERS, you can quickly and easily extract out your THC and clean up a lot of the extra stuff in the sample that will interfere with your analysis and crud up your instrument. Your description of the QuEChERS process was actually pretty good, basically, you take some brownie or other edible, add water and acetonitrile, add salts, shake it up, and centrifuge it. At this point you’ll have an acetonitrile extract that contains your THC, but it also contains a lot of the other food ingredients as well. I wouldn’t recommend injecting this on your instrument unless you like cleaning burnt food out of your injection port. Fortunately, it’s relatively easy to clean up a lot of the food interferences. To clean up the sample, you just take a portion of the acetonitrile extract and shake it up again with some other products that are designed to remove fats, sugars, and pigments. Centrifuge that down, and you’ll have a much cleaner sample ready for injection. The great thing about these cleanups is that they can be tailored to different edibles. If you have a hard candy, then you can just use something to remove sugars and pigments because you don’t have to worry about fats. I do have a couple of draft methods for edibles, but I don’t want to post them here for public consumption, because in all honesty, I’m not sure if they work. Unfortunately, marijuana is still completely illegal in Pennsylvania, so I have no way to test authentic samples. That being said, feel free to have Allan give me a call and I’ll tell him everything he wants to know and try not to bore him to death in the process. Thanks again for posting! By the way, even with a chemistry degree, one can get themselves into trouble developing analytical techniques. I try to consider the pain and suffering of method development a character-building exercise. -Amanda

Tue, Apr 26, 2011

Hi Amanda, Good Stuff! Thank you for your insiteful information on the Quechers methods and how it might be able to be used for the extraction of cannabinoids from food products! This has been our largest challenge in Colorado. We are trying to keep our methods as 'Green' as possible, and with the average price per test running less than $30 a liquid/liquid extraction method cannot be profitable. Please let me tell you that I am on the business side of things here at CannLabs, and that you will be hearing from our chemist (Allan Bumgartner) shortly, however, I seem to be the problem solver of the company but with a Mechanical Engineering degree / MBA I seem to know just enough to get myself into trouble when it comes to how easy or extensive the chemistry tends to be! With that said, I spoke with a colleague of yours, Neil M. this afternoon and he briefly went over the process and why he believed Quechers would be superior to headspace SPME, which after reading a few papers seems to be pretty good. If I understand the process correctly, we place our sample in a vial, add acetonitrile, some salts, centrifuge, decant, (now this will show my lack of experience/knowledge) shoot on the GC??? or after decant add extractant then shoot... ??? Close??? For some background we currently use .1g product (leaf,oil,hash,etc) in a 40ml vial with solvent & shoot...I could be wrong but the MX-5 sounds familiar for our column with your standards ofcourse... If we can help you come up with a method or if you have one already which you could share that would awesome...as you mentioned in one of your blogs that there is all sorts of chemistry going on out there and we would like to become the leader in standardizing one proven method that doesn't require large amounts of solvents & time....ie GREEN or at least Greener... Thanks for your help in advance, Jon Furda

Tue, Jun 14, 2011

Great article Amanda. We have been using a very similar method for a couple of years now with great success. Your QuEChERS products are attractive though since they are so simple. I think I will give them a try. I suggest using a sonicator as well. Really helps to break up the samples. Thank you Restek!