contaminant
noun [ C ] chemistry specialized uk/kənˈtæm.ɪ.nənt/ us/kənˈtæm.ə.nənt/
致污物，污染物
a substance that makes something less pure or makes it poisonous
Make sure that all equipment is clean and free of contaminants. 要确保所有设备是干净、未受污染的。