Spin trapping of superoxide in aqueous solutions of fresh and aged cigarette smoke.

Superoxide generation in aqueous solutions of cigarette smoke was determined as a function of the age of smoke using spin trapping. As a spin trap, 5,5-dimethylpyrroline-N-oxide (DMPO) was used. The superoxide adduct of DMPO was detected in a solution of fresh main-stream smoke for over 1 h. The superoxide-generating potential of smoke was rapidly lost as the smoke was kept in a plastic syringe. The smoke that was aged for 3 min did not generate superoxide. Additional evidence of superoxide generation in aqueous solutions of cigarette smoke was obtained by the chemiluminescence method.