Rotary evaporator, also called rotavap or rotovap, is a commonly used lab instrument in chemistry laboratory, mainly used in continuous distillation of a large amount of volatile solvent under negative pressure. Especially for the concentration of extract liquor and distillation of receive liquid when chromatograph. Because evaporator is vacuumized, to be distilled solvent’s boiling point depressed. In general, ingredient which is distilled form sample is the target ingredient in chemical research, such as extracting some natural ingredient from organic synthesis sample. Rotary evaporator mostly is used for isolating low-boiling ingredient, such as hexane, ethyl acetate, that presenting liquid state under indoor temperature and normal pressure. Besides, it can dislodge some ingredient in sample by standard operation.