A small quantity of the oils is analyzed under specified conditions. The alpha- and beta-thujone contents are determined by using the internal standard or addition method. As stationary phase are used cyanopropyl methylphenyl methyl silicone, or trifluoropropylmethyl silicone, or polyethylene glycol 1500. Operating temperatures: Oven: isotherm about 100 °C when using cyanopropyl methylphenyl methyl silicone or trifluoropropylmethyl silicone; isotherm about 130-°C when using polyethylene glycol 1500. Injection system and detector: about 170 °C.