Testing the purity of street drugs is a complex and dangerous task that usually requires specialized chemical analysis equipment and laboratory conditions. Here are some possible methods, but it is not recommended for individuals to try on their own: 1. **Reagent testing**: In some countries, you can buy reagent kits for testing drug ingredients. These reagents can be used for preliminary screening, indicating the presence of certain chemical ingredients by changing color. But this does not accurately measure purity. 2. **Infrared spectroscopy analysis (FTIR)**: This method uses infrared spectroscopy to analyze the chemical composition of drugs and is one of the commonly used testing methods in laboratories. 3. **Gas chromatography-mass spectrometry (GC-MS)**: This technology is very common in laboratories and can accurately analyze the composition and purity of chemical substances. 4. **Liquid chromatography (HPLC)**: This is a method used to separate, identify and quantify the components of a mixture, and is also commonly used in drug testing. For safety reasons, any test for drug composition or purity should be performed by professionals in a safe environment. It is not recommended that individuals attempt to test on their own, because exposure to drugs of unknown composition may cause serious health risks or legal problems. If you suspect that a drug is adulterated or poses a health hazard, you should seek professional help immediately.