Thin Layer Fluorography of Tritium-Labeled Compounds
Thin layer chromatography followed by autoradiography is an important tool in metabolic studies. Small amounts of labeled compounds can be visualized by film blackening, provided that the isotopic label possesses sufficient energy to reach the photographic emulsion. This is the case with most commonly used isotopes — such as 32P, 14C, 35S — but it is not so with tritium. The maximum energy of tritium is only one-tenth of the maximum energy of 14C. The β -range of tritium in silica gel is less than 13 µ. The silica gel thin layers used for chromatography are generally 250 µ thick, which is twenty times the range of the tritium β -particle. More than 95% of the β -radiation is lost by absorption in the thin layer. A further loss occurs in the gap between the thin layer chromatogram and the X-ray film. The remaining β -particles hit the photographic emulsion, but they may not necessarily hit a silver grain, since the distance between the silver grains in an X-ray film may vary between 1 and 12 k, and the range of a 3H β -particle in a photographic emulsion is only 1 µ . Therefore, a greatpart of the remaining radiation is again lost.
KeywordsBile Acid Photographic Emulsion Zinc Sulfide Label Compound Thin Layer Chromatogram
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