Drug Test: How To Find Out If Your Meth Is Racemic or DL(+)/L(-)?

I came up with a very straightforward optical activity or drug test for a sample. So now you don’t have to worry about whether your meth or ketamine is racemic or d-meth/S(+)-ketamine as advertised.

Background

Chirality refers to the number of stereoisomers for each chiral center. For example, meth and ketamine have 1 chiral center and 2 stereoisomers, and LSD has 2 chiral centers and 4 stereoisomers, respectively.

When two chiral center molecules are mirror images, they are called enantiomers (or optical isomers). The optical isomers will rotate plane polarized light to the right or to the left in clockwise (or counterclockwise (or clockwise)) rotation. For this reason, they are denoted by + or -, or d or l, as d-methamphetamine or s(+)-ketamine.

Note: This does not refer to the conventions R,S, or D,L, which refer to the spatial arrangement of groups around the chiral center.

Optically active compounds contain more of one of the two enantiomers than the other, i.e., they have a non-enantiomeric (i.e., non-1:1) ratio. As a result, they exhibit a measurable skew in the light rotation direction corresponding to the dominant one. (Chiral purity (ee) is measured as enantiomer excess, i.e. the percentage of the dominant one less than the percentage of the less dominant one. For example, an ee = 0% means that the substance contains equal parts of dextro (dextro) and levrotary (levorotatory) enantiomers. An ee = 100% indicates that the substance contains one version (enantiopure) of the molecule.)

A racemate, also known as a racemic mixture, is a mixture of enantiomers that are 50/50 (1:1) equal parts. Because it is an even mixture, clockwise rotation cancels out counterclockwise rotations. Thus, net optical activity is not present in a racemic mixture.

Drug Test Procedure Of Meth

Now that we have that in mind, let’s move on to the process. We’re going to build a polarimeter. A polarimeter is a device that allows you to measure specific rotation, i.e., the degree to which a sample rotates the light.

In reality, a polarimeter is more like a polariscope. It doesn’t measure specific rotation or allow you to differentiate enantiomers. Instead, it just lets you visualize the optical activity of a non-zero enantiomer excess sample.

The first thing you’ll need is a smartphone or tablet. Ideally, you’ll want one that doesn’t have a plastic/glass cover over the screen. For this drug test, if you have one of these over the screen, you may want to temporarily remove it and then put on a new one. My phone that had one of these on the screen didn’t work well for this test. I still recommend using the liquid screen protecting compound, liquid glass, or whatever it’s called.

Why do we need a device?

Your smartphone or tablet’s screen will most likely emit linearly polarized light.

The next thing you’re going to need are polarized sunglasses.

If you don’t already have polarized sunglasses, buy some.

You can also buy a sheet (not circular) or a linear polarizing film / linear polarizing filter from Amazon for under $20.

We will require a shot glass and some acetone as the final two items.

Use a smartphone flashlight app that turns on your screen at maximum brightness and displays a white screen. Turn it on and open the app. Look at your phone screen through one lens of your sunglasses or through the film of your sunglasses. Everything looks good, but slowly start rotating the lens / film clockwise. You should notice that as you rotate, more and more light will be blocked out until you reach maximum opacity. If nothing happens while you are doing this, either your phone doesn’t emit polarized light or your sunglasses aren’t polarized.

Now, one of the ways to do this drug test is by using a 5 to 10 ml graduated cylinder with a few ml concentrated (1 g/ ml) solution made from your compound to test, along with a standard solvent like distilled water or acetone (or ethanol), methanol (or DMSO), etc.

In this version (and my modified version), you place your graduated cylinder on your phone screen (with the flashlight app on) and then look directly down the cylinder (through your lens/film) and rotate the lens and observe.

I didn’t want to use more than a few grams of meth in this drug test, much less dissolve it in water, since it’s hard to evaporate. With a bit of tweaking, I found an even easier method that follows the same principles, but uses a much smaller amount of your sample.

Using a shot glass, place a few small shaker-sized crystals of your sample on the bottom of the glass (or if it’s a powder, that’s fine too). Add a small amount of acetone to the top. You don’t need to add much, 5-10ml should do the trick. Stir a bit to allow the particles to spin and settle at the bottom into an even pile.

Note: I said acetone. In my example, I’m using methamphetamines, which are soluble in acetone. The main difference here is that in my modification, we’re going to pass polarized light through a thinner layer of our compound, while it’s still a solid. Acetone also works for Ketamine. Choose your solvent accordingly.

Now, take your solution-filled shot glass and place it on top of the phone screen while activating the flashlight app. Hold your lens/film above the glass and look straight down through it. Rotate the glass. If your sample has a racemic lens, you won’t see anything, but if it has an optically active lens, you’ll see a significant fluorescence.

I demonstrated this using NaCl (NaCl + Sodium Bicarbonate) and then optically activated d-meth, both as a powder and as a shake crystal. I also tested this procedure on some S+ ketamine I had and confirmed it was not racemic.

Why Do Racemic Mixtures Have No Optical Activity?

They cancel each other out. Levorotatory compounds rot light to the left and dextrorotatory compounds rot it to the right. Therefore, in a racemate, there is no net rotation, and the sample is described as optically inert.

Rotation of plane polarized light occurs only in mixtures with net optical activity. Therefore, the two requirements are:

• The molecules in the solution must have a chiral center.
• The enantiomers must have an uneven balance.
• Enantiomeric excess is also denoted by ee%.

Compounds with two enantiomers in unequal proportions are rare to occur naturally. Cocaine, for example, is found only as the (-)-Cocaine form of coca in plants, or as racemic (e.g., ephedrine, ephedra) in plants. This is the case unless they are produced synthetically by asymmetric synthesis, or are resolved enantiomers, in which case the ratio is changed manually in an effort to isolate one.

Optical rotation is measured in specific rotations, which are expressed as degrees of rotation observed with a polarimeter by dividing the concentration by the path length (the length of the light path, usually the size of the cuvette in the polarimeter).

For simplicity’s sake, most of the ionic compounds we’re thinking about, like sodium chloride and sodium carbonate and so on, aren’t chiral, so they don’t have optical activity, and we’re getting into some pretty complex topics here.

However, chirality exists in some inorganic compounds. For example, there’s tris (ethylenediamine) cobalt(III), which has a cobalt ion surrounded by three (bidentate) ethylene-enediamin ligands arranged in the octahedral form. It has both left and right-handed forms, but they aren’t expressed in the same way as chiral organic compounds.

Final Thoughts

This is a qualitative drug test rather than a quantitative one. Basically, we are visualizing the specific rotation through a solid phase sample.

To measure and report the specific rotation, we would need a fixed wavelength light source.

Specific rotation is reported in degrees, but similar to the way specific gravity is reported for water, the specific rotation is reported for two other values: temperature and wavelength.

The temperature is usually 25 degree Celcius and the wavelength is 589.3 nm.

A sodium lamp D line is used as the light source.

I would say the benefit of this method is that it’s very straightforward, easy to visualize, and doesn’t require any specialized equipment or knowledge.

It’s a bit ironic considering chirality is the only thing that sending a sample to an analytical laboratory like EC wouldn’t give you information about, as most labs say they don’t have the equipment because they aren’t going to order and set up a costly chiral column specifically for your specimen.

This method doesn’t tell you what your enantiomer is, but fortunately that’s usually something we can make an educated guess about.