There are some rapid test strips and reagents on the market that can be used to detect the composition of illegal drugs, but they are mainly used to screen the type of drugs rather than directly measure purity. These test kits are usually targeted at specific ingredients or compounds. When the sample comes into contact with the test strip, a color change occurs, which makes it relatively easy to determine whether the sample contains certain drugs. However, regarding the purity test of drugs, more complex laboratory analysis is usually required, such as gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-mass spectrometry (LC-MS). These methods can provide more accurate component analysis and purity determination. If you consider using these test kits, be sure to understand their limitations and comply with relevant laws and regulations.