There is still a considerable number of seizures of illicit cannabis in Japan. In addition, the prevalence of herbs containing synthetic cannabinoids becomes a serious social problem. Because of an increasing number of cannabis and herb samples encountered in forensic science laboratories, it is required to develop a rapid method for identification and discrimination of cannabis and its related herbal products. In this study, general methods for microscopic morphological examination were improved. The decolorization of cannabis in 10% NaOH in water-methanol mixture (1:1, v/v) at 60°C for 10 min was as efficient as the general decolorization (boiling in 10% NaOH for 20 min), and was carried out faster and safer than the general method. In addition, the microscopic observation by polarized light allowed easy identification of hairs (trichomes) characteristic in cannabis. Using a 96-well plate allowed to examine many samples at the same time. By the combination of color reaction with Fast Blue B, this method can be applicable to identification and discrimination of a large number of samples as a screening test.
