Dr. Michael Clark, a psychiatrist and molecular biologist at Seattle’s Harborview Medical Center, invented a relatively cheap and easy-to-use street test kit to detect the presence of levamisole in—well, in anything. The kit requires no special, rare, toxic, or restricted ingredients and should be easy to assemble in most basic labs. Read through the recipe and make all solutions used before starting a test. They will stay good for several months—or even years—if stored in glass bottles.
Typically, we make a few hundred kits at a time and then distribute them for testing. You can find cartoon instructions on how to use the test (plus some visuals that might aid in assembling them) here.
His recipe:
Step 1: Get 2 test vials. We use disposable spectrophotometer cuvettes—the only requirement is that they’re clear and can hold 3.5 mL or more. The first vial is for testing your sample; the second vial is a control for comparison.
Step 2: Make the reaction buffer. It consists of 1M diethanolamine and 0.5 mM magnesium chloride adjusted to pH 9.8 with hydrochloric acid. We typically make this by the liter. It can be stored at room temperature for several months in glass bottles.
Step 3: Get 0.25 mL of 150 mM fresh para-nitrophenyl phosphate solution, or a stabilized substrate like Pierce 1-Step pNPP for each vial. We use Pierce 1-Step pNPP because we tested it for stability (4 weeks at room temperature in the dark, no change from baseline) and because it claims to have no toxic components.
Step 4: Get 2.5 units of bovine kidney alkaline phosphatase for each vial. This enzyme is sold in “units” (typically by the kU, which is 1,000 units). One unit of enzyme is the amount needed to produce one micromole of p-NP from p-NPP each minute.
We rehydrate the enzyme at a concentration of 1.25 units per microliter in an enzyme buffer containing 50 mM Tris-Cl, 100 mM NaCl that has been adjusted to pH 8.0 with HCl. The enzyme buffer should be prepared in advance. We usually make 250–500 mL of buffer at a time. The buffer will stay good for years if stored in a glass bottle. Once rehydrated, the enzyme solution will stay good for “several months” at 4°C, per the original characterizing paper.
We pipette 2 uL (2.5 units) of the bovine kidney alkaline phosphatase onto disposable plastic cuvette caps that fit our test vials. The caps are then freeze-dried—using a vacuum pump with a cold trap—and packaged with silica gel desiccator packets in a tightly sealed container until ready for use. If using liquid enzyme solution stored in the fridge, freeze-drying is not necessary.
Now that you’ve assembled your components—vials, reaction buffer, substrate, alkaline phosphatase enzyme—you can move on to testing your sample.
Test step 1: Add a small (about 20 mg) sample of powder or crack cocaine to the bottom of the first vial (the vial for testing your substance), but not the second (the control vial). If the sample is crack, you need to dissolve it with a few drops of 50% (weight/volume) citric acid.
Test step 2: Add 2.25 mL of reaction buffer to each tube.
Test step 3: Add 0.25 mL of 150 mM fresh para-nitrophenyl phosphate solution, or a stabilized substrate like Pierce 1-Step pNPP, to each vial.
Test step 4: Place the caps (with the alkaline phosphatase enzyme) on the top of each tube and press down to seal.
Test step 5: Mix the contents of the tubes by turning upside down and back several times; wait 30 seconds while watching carefully.
Possible Results
If both vials turn yellow at approximately the same rate, levamisole is not present. (Since levamisole is a potent inhibitor of alkaline phosphatase, the test is looking for an inhibition. Therefore, if the chemical reaction—turning yellow—occurs, there’s no levamisole.)
If the first vial does not change in 30 seconds or develops a yellow color more slowly than the second tube, levamisole is present.
If the second vial (the control vial) does not turn yellow, something went wrong. Repeat the test.
This kit is sensitive to 0.25–0.5% levamisole (weight/weight).
If you have questions about this test kit or levamisole-tainted cocaine in general, please e-mail cocaine@thestranger.com.
So just to make sure, bottle A is 50% w/v citric acid, bottle B is reaction buffer, and bottle C is pNPP solution. If you’re using powdered coke (not crack), then bottle A shouldn’t be necessary.
This is really good, accessible biochemistry! I wish I could teach this to my students.
I got a better idea. How about you just realise that doing cocaine is about as unethical as running over a dolphin in a humvee and stop doing it. Cocaine = Slave labour, literally
@2
Why do you hate America?
@2 Cocaine turns its producers as well as its users into slaves. What is being attempted here is to poison as few of the cocaine slave users as possible. Thanks for the input!
Why are people who use cocaine worried about ruining their immune systems, but not their septums or the rest of their health?
If somebody is dumb enough to do coke what on earth makes anybody think they’re going to even remotely come close to following the steps outlined here?
Retard @2, you’re suggestion that people just “stop doing it” sounds a little too much like “Just say no”. In case you don’t recall, that was our countries policy for decades and it didn’t work out all that well.
I meant country’s
For some reason I suspect that most users aren’t up to doing the stoichiometry required to make these reagents. Hell, I’ve met lab techs who weren’t up to it …
@1
Bottle A is 50% citric acid. And it isn’t necessary for powder cocaine. But it simplifies the instructions to always use bottle A. Adding citric acid will not cause a problem for powder, but NOT adding it for crack may cause a big one.
And it is a great biochem teaching lab. Just use faked samples. Mannitol spiked with levamisole vs. mannitol alone. If the drug war politics raises eyebrows, just make the students into toxicologists at the state crime lab.
Retard #2 here.
@3 Why do you think that America is the only western country that abuses coke and hence supports slavery. But well spotted that I’m not from Seattle.
@4 Good point. It’d be good if people didn’t try Coke for the first time because they were aware that it is made in the equivalent of sweat shops.
@7 I am saying ‘Stop doing it’. But I’m saying why. There’s no reason to stop doing a recreational drug if it’s not hurting anybody. But it is hurting someone every time you do a line. That sucks. Switch to something else.
I would just like to add that cocaine is awesome.
http://i.imgur.com/PIXTJ.jpg
I am dismayed at the level of ignorance and lack of compassion divulged in several statements above. The work done by Dr. Michael Clark is aimed at helping people & saving tax dollars. Clearly the socio-economic factors involved in this tragedy are beyond your comprehension.
Levamisole is a potent inhibitor of calf alkaline phosphatase enzyme activity but several other simple compounds can inhibit this enzyme at higher concentrations. Cysteine, phenylalanine and homoarginine are amino acids not likly to be found in street drugs unless intended for bodybuilders. Sodium borate (borax powder) is known to inhibit the activity of calf alkaline phosphatase and may sometimes be used as a cut for coke. That could result in a false positive and what then- throw the expensive coke out? Wouldn’t that disrespect the lives lost in Mexico and Columbia who produced it at such great risk?