Ahhh drug testing. A marvellous application of medical science for the most bastardly of reasons. Apparently, it matters to other people what do you get up to safely in the privacy of your own home. This post takes you through the basics, the science behind it all, talks about how legal highs fit in and finally the best way to beat them!
A standard “drug test” will look for any of the following: cannabis, cocaine, amphetamines, MDMA, opiates (and methadone), PCP, barbiturates, benzodiazepines and tricyclic antidepressants. You’ll be required to give a sample in the form of hair, urine, sweat or saliva, which is pretty fucking obtrusive, considering you’ve not actually murdered anyone. The top reasons for being tested include applying for a new job, random testing while you’re at work or you might be in some kind of trouble with the law, such as driving while battered or being on probation. I disagree much more with the work-related tests than I do for those involving the law (unless your offence is drug related). No one should drive while under the influence of anything. Anyway…
First, your sample will be tested with a simple, cheap screening test. Since these aren’t 100% accurate, a positive score on one of these will qualify your sample for a second, much more expensive confirmation test to rule out any false positives. Test positive on both and you’ll probably be in some kind of trouble.
How Do Drug Tests Work?
The preliminary screening tests are based on immunological methods. This means that somewhere along the line, antibodies are used to detect any drugs in your sample. Antibodies (or immunoglobulin proteins) are a true evolutionary masterpiece. Your basic antibody is made up of four protein chains — two light and two heavy — which together form a Y shape. Every member of a particular family of antibodies shares the constant region with each other, while the variable region … varies. This variation is important since this is the business end of the protein. Normally our white blood cells produce antibodies, which poke out of the cell membrane. When they encounter a pathogen (a bacterium for example), the variable region of the antibody might bind to its surface. Whether or not it binds depends on whether or not the protein sequence at the variable regions is the right shape to fit it. Since our bodies have no way of telling what’s going to attack us next, they produce millions of antibodies with different variable regions in the hope that just a few will be the right shape to bind to the next invader. If the antibodies on a white blood cell happen to bind to something foreign in our bodies, that white blood cell then shits out tonnes more of the same antibody, and we become immune to whatever it is that’s destroying us from the inside.
So what’s this got to do with drugs testing? Well, a common way scientists try and look for stuff in samples is with the help of antibodies. First, the scientist needs an antibody for something. That means that the antibody has the right shaped variable region to bind to whatever it is the scientist is looking for. That antibody is normally produced by repeatedly injecting whatever the something is into an animal, such as a rabbit. Then, after a while, you kill the rabbit, collect it’s blood, and purify out the antibodies (mwuhahaha!)
Once you have an antibody specific to the thing you’re looking for, you can do any number of immunoassays to test whether or not that something is in your sample. A pretty standard example is the ELISA (or enzyme-linked immunosorbent assay :o) protocol. It might sound totally incomprehensible, but it’s actually a piece of piss. It must be, considering that I’ve done more of these than I care to remember. The gist
is as follows:
- Attach your antibody to the bottom of the wells in your plate (each well is like a little mini test tube that only holds a few microlitres of liquid; a typical plate might have 8 rows and 12 columns, making it a 96 well plate)
- Add your sample to each well
- Wait for a bit, so the stuff in your sample has chance to bind to the antibodies at the bottom of the wells
- Wash the entire plate. Anything not bound to the antibodies (ie everything you don’t care about) will wash off, while anything of interest remains stuck to the bottom of the well.
- Add some more of the original antibody, then wait for a bit and wash again. This makes sure that your molecule of interest is surrounded by antibody on all sides
- Add your secondary antibody. This is a much more general antibody that was selected to recognise the constant region of the original antibody. This will also have been engineered to contain an enzyme, such as horse radish peroxidase, which is necessary for the genius that is step 8
- Wash once more to get rid of any unbound secondary antibody
- Add a something that changes colour in the presence of the enzyme attached to the secondary antibody. If there was the molecule of interest in your original sample, then your original antibody will bind to it, holding it in the well. The secondary antibody will bind to the first lot of antibodies, and since it’s got an enzyme attached to it, it will change the colour of the well.
- Measure the colour change of the wells. The more the colour has changed, the more of that something there was in your original sample
That’s it. Geniusly straightforward. There are tonnes of variations on this assay, like attaching something radioactive to the secondary antibody then measuring the amount of radiation present, rather than colour change. A fluorescent tag would also do the trick, allowing you to measure the amount of light given off. This is also the same kind of thing found in a pregnancy test, which changes colour if the hormone human chorionic gonadotropin is present in your piss.
That’s the screening test, but what about the confirmation tests?
Confirmation tests rely on two techniques: gas chromatography and mass spectrometry.
Gas spectrometry separates the sample into its component parts by forcing it through a column with an inert gas at high pressure. Different compounds stay in the column longer than others, so their retention time is what is used to differentiate them. Mass spectrometry is then used to give us the “molecular fingerprint” of the compound in question. When a sample is added to a mass spectrometer, it’s bombarded by electrons which split the molecule up into fragments. The way a molecule breaks up is unique to that molecule, so analysing the fragments tells us exactly what was put into the machine. The two techniques provide a very accurate (and expensive!) way to check for drugs in your system.
While we might despise drug testing, you have to admire the awesome science behind it all!
The following table lists the amount of time a substance is detectable in your urine, hair, blood or saliva. In case anyone was wondering, I robbed it from Wikipedia.
Do Legal Highs Show Up On Drug Tests?
So, what do we know about drug testing so far?
- They check for specific molecules one at a time
- The checks are based on the molecule’s size, shape and charge, which are unique to that compound
- While a screening test might be cheap, the confirmation tests certainly aren’t, which means a lot of money has to be spent to say for sure that you’ve been taking drugs
While legal highs might mimic the effects of illegal drugs, the active ingredients are certainly not chemically identical to the drug itself. Some legal highs might be structurally related (or analogous) to illegal drugs, but they’re still not exactly the same, and other legal highs share no similarities with their illegal counterparts, they just tickle the same receptors in your brain. This rules out any chance that having legal highs in your system will accidentally cause a positive result.
Add to that the fact that legal highs aren’t actually illegal (the clue is in the name…), then why would a lab bother spending a lot of money to confirm that you’ve consumed something legal? The technology certainly exists to check for legal highs in your system, but since you’re not breaking the law, it would be a massive waste of money. Unless of course, your employer has more money than sense and no regard for personal privacy. Just make sure you’re not high at work, and you’ll be fine. I imagine the rules about that would be the same as alcohol — that’s legal, but no one would want you to turn up to the office completely hammered.
If I get another “Does salvia show up on a drug test” email, then I’m pointing them to this post!
How To Beat A Drugs Test
Fortunately, there are many ways to score a negative result on the initial screening test, meaning you won’t even come up against the scary confirmation test. Here’s the gist for each:
Helping Your Body Clean Itself
Eat healthily, drink plenty of fluids, and start exercising! THC in cannabis is fat soluble, so stays in your fat cells. The only way you’re going to get rid of that is through cardiovascular exercise, or a high fibre diet.
Producing Clean Urine
Unfortunately, drinking a shitload of water before your test won’t be enough. To prevent this from happening, creatinine levels are also analysed. If the concentration of creatinine is lower than it should be, then it’s a pretty good sign you’ve been trying to dilute your piss. Fortunately, there are ways around it. Creatinine is the breakdown product of creatine phosphate, which is used for energy in muscles. Since red meat is pretty much all muscle, eating lots of it starting from three days before your test will help raise it to an acceptable level. You can also chomp 100mg of Vitamin B to make your pee yellow. Diuretics will also help you pee more frequently, and include caffeine, alcohol, cranberry juice and many more.
Substituting Someone Else's Sample
A great yet disgusting way to evade detection is to use someone else’s clean urine. This can work wonders is you do it right. If no one’s watching you pee, you can strap a container to you leg and empty it into your sample bottle as soon as you’re left to it. In case its temperature gets recorded, you might want to “collect” the clean sample only minutes before your test. If that’s not possible, or your test is supervised, you can put the clean sample straight in your bladder. Say whaaaaat? Yes, that’s right. First you’re going to need to empty your bladder the old fashioned way, then catheterise yourself and inject the sample straight into yourself down the tube. It’s going to be uncomfortable, but your sample will be drug-free, warm, the correct pH and come out of the right hole, which is especially handy for supervised tests.
These work by interfering with the assays to produce a negative result. The only valid drug screen seems to be Aspirin. Apparently, taking 4 aspirin a few hours before the test prevents a positive result by interfering with the absorption of light during step #9 discussed earlier. I certainly wouldn’t trust any commercially available products to do the job for you. Most are untested or simply don’t work..