A range of analysis techniques are in use by drug checking services. The most common are reagent testing, fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, raman spectroscopy, mass spectrometry and gas chromatography mass spectrometry.
Reagent testing uses chemical indicators that show a colour change in the presence of particular drugs. These tests are widely available and affordable. The use of several reagents is generally necessary to positively identify a substance with Marquis, Mandelin, and Mecke reagents being used to detect MDMA and Ehrlich's reagent common for detecting LSD. However, reagent testing only indicates the presence of a substance, not the absence of contaminants or other substances. This can provide a false sense of security when illicit drugs are deliberately adulterated to fool reagent tests. 
The presence of specific drugs can also be detected through immunoassay testing strips. Testing strips for fentanyl can detect a few tens of nanograms of the substance at a price of a few dollars per test. Recent increased demand for immunoassay test strips, lack of regulation, and approval to use federal funding for test strip purchasing in the US have led to a boom in test strip manufacturers creating concern in drug checking programs and harm reduction organizations about the lack of validation, consistency, and accuracy of results.
Fourier transform infrared spectroscopy is a rapid test using robust hardware that can be carried out in the field. It provides sample identification and mixture analysis, allowing the detection of impurities and adulterants. It is highly sensitive and can carry out analysis using only a few milligrams of a sample. It is semi-quantitative and can provide an indication of purity. For these reasons, it is widely used by both fixed and mobile testing services and considered the best technology to use.
Gas chromatography mass spectrometry provides very sensitive and quantified information about substances. However, the high price and delicate equipment generally limit the use of this technique to fixed sites.
The RADIAN ASAP is a novel, dedicated direct analysis system specifically designed for rapid, easy and low-cost analysis of liquids and solids. Engineered using proven and robust single quadrupole mass spectrometry technology combined with the Atmospheric Pressure Solids Analysis Probe (ASAP), the RADIAN ASAP delivers quality and ease of use in a compact footprint. RADIAN ASAP screens samples in less than 5 minutes against a library of known compounds for rapid, confident identification of illicit drugs. The sensitivity and selectivity of mass spectrometry provides confidence in detecting drugs with an easy, efficient triage workflow.