Fluorographic detection of radioactivity in polyacrylamide gels with the water-soluble fluor, sodium salicylate.

Fluorography has recently achieved widespread usage for detection of radioactivity in polyacrylamide gels (1,2). Aqueous gels are equilibrated with dimethyl sulfoxide (DMSO),’ impregnated with fluor PPO dissolved in DMSO. soaked in water to remove DMSO, dried, and exposed to X-ray film at -70°C. The use of DMSO is necessitated by PPO’s insolubility in water. /3 particles, instead of directly interacting with the photographic emulsion as in conventional autoradiography, cause the fluor to produce multiple photons which activate the film. Fluorography increases the sensitivity for 14C and 9 about IO-fold, and permits detection of :sH which cannot be detected with conventional autoradiography. The response is linear if the X-ray film is presensitized with a flash of visible light (2). For all its advantages, the current method has several drawbacks. It is somewhat tedious, requiring 5 h from the start of DMSO equilibration to the end of the water soak. It is also costly, even if excess PPO is recrystallized and reused. For these reasons, 1 have sought a rapid, inexpensive method employing a water-sol-