The aerial parts of D. assadii Alava. were collected in the wild from Lalehzar (Kerman Province, in southern Iran) at the flowering stage, in July 2007. The material was dried at room temperature and used for distillation. Distillation: A direct-fired field distillation unit containing a distillation tank (capacity: 1,000 L), a condensation column and receiver, all made of stainless steel, and which can process 30-50 kg of dried aerial parts from the plants/batch, was installed at an altitude of 2600 m (boiling point: 87 ℃). Dried aerial parts from the plants (40 kg) were charged into the distillation unit along with 500 L fresh water and the unit was heated by steam. The system was kept open to atmospheric pressure until the temperature reached to 70 ℃, when the air present in the unit was replaced by the vapor. After complete removal of air from the unit, the air vent was closed and the whole unit was operated as a closed system under pressure to distill the oil. The pressure, temperature and rate of distillation were controlled manually. The process was completed after the collection of 500 L of water distillate. The oil collected in the receiver and dried over anhydrous Na₂SO₄. Extraction of Ducrosia Second Oil From Ducrosia Water by Redistillation: The seprated distillate water collected in the receiver was redistilled in a 1,000 L still to yield more Doucrosia oil (this oil is known as secondary essential oil, second oil, cooked oil or indirect oil).

Fifty components were identified in a second oil of D. assadii from Lalehzar with decanal (35.2%), nonadecane (12%) and citronellyl acetate (11.6%) as the main constituents. The oil from Dehbakrii also contained decanal (36.4%) as the main component of an oil recovered from the distillate water. The results showed that the amount of decanal is remarkably high in the oils of D. assadii.