Microscopy standardization reagents

In some laboratories, the analysis stops with the Duquenois-Levine test, but many add TLC with standards as the final step, using the dye Fast Blue B (which is carcinogenic), or Fast Blue BB or the Duquenois reagent as a developer. Fast Blue B gives the constituents distinctive colors A -THC turns red, CBN purple, and CBD orange. The combination of microscopy, the Duquenois-Levine test, and TLC with standards is considered conclusive identification for marijuana. Quantitation of THC is currently not required in the United States. Derivatization techniques can be used for GC, but HPLC is better suited to such analyses. 

---