Drug Testing Basics

Drug testing generally involves one or more of the following:

  1. Identifying substances
  2. Identifying adulterants (“cuts”)
  3. Testing substance purity

We elaborate on each concept below.

Note: The methods listed below aren’t 100% conclusive. Lab analysis using gas chromatography–mass spectrometry is considered the gold standard.

Identifying Substances

Use a substance identification kit to presumptively identify a sample. Testing involves placing a drop or two of a testing liquid (reagent) on a small part of your sample, and observing the color change, or lack of a color change.

Presumptive tests, in medical and forensic science, analyze a sample and establish one of the following:

  1. The sample is definitely not a certain substance.
  2. The sample probably is the substance.

The easiest way to see how a test is done, is to check out an identification test demo video:

Using more than one test is recommended, to decrease the chances of a false positive, and to help screen for adulterants.

You may also take a look at our drug test color reaction results page, to see what color reactions you can expect for different substances.

Detecting Adulterants (“cuts”)

Identifying cuts in a sample can be done using a test that doesn’t yield a color change with a pure sample. For example, the Marquis and Mecke tests don’t produce a color change with ketamine, which makes them good for identifying adulterants. Similarly, Marquis doesn’t change colors with pure cocaine, and produces a red color with amphetamine. This makes Marquis a good test for amphetamine in cocaine. Ideally, you’d choose a test that doesn’t interact with the desired substance, but does change colors with the typical adulterants for that particular drug.

To screen for fentanyl, we recommend a fentanyl test kit.

Testing Substance Purity

A quick way to get an idea of the purity of a sample, is to use a drug purity test. They give an indication of what proportion of a sample contains is the drug in question. They generally will not show you what cuts are in a sample, only what ratio of your sample is the intended substance.