With the object of checking the stability of domestic rice bran oil, manganese and copper in trace amounts were analysed by neutron activation analysis. Manganese was determined by the nondestructive method after it was irradiated at the pneumatic tube （neutron flux=3.4×10¹² n ㎝^-2 sec^-1） of the TRIGA MARK II reactor for 10 min. and copper by the destructive method which uses an anion exchange resin to concentrate copper after irradiation for 1 hr.
The manganese and copper contents （along with the respective experimental standard deviations） of dewaxed crude oil, deacidified oil, bleached oil and deodorized oil, sampled from each process of one batch processing, were 13.4±0.4, 2.6±0.2, 0.24±0.01 and 0.33±0.03 and 0.24±0.03, 0.21±0.03, 0.056±0.007 and 0.040±0.002, respectively.
The contents of manganese in domestic rice bran oil compared with that of a foreign product are extraordinarily high, while the copper contents seem to be in the similar level as the contents of foreign products.