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Appendix D: S-35 Information and Safe Handling Guide


Radioactive half-life 87.4 days
Decay mechanism Beta emission
Energy Emax = 0.167 MeV
Contamination monitoring Thin window Geiger Mueller detector, liquid scintillation counter for wipe
Dosimetry Urinalysis bioassay
Shielding 1 cm Lucite

  • Radiolysis of S-35 labeled amino acids may lead to the release of S-35 labeled volatile impurities. Delivery vials should therefore be opened in a fume hood.
  • S-35 may be difficult to distinguish from C-14. If both nuclides are being used in the same laboratory, establish controls to ensure they are kept separate. If "unknown" contamination is found, treat it as C-14.
  • Beta particles from S-35 travel a maximum of 24 cm in the air.
  • Most Geiger counters cannot detect S-35 and special precautions must be taken to keep the work environment clean.
  • The maximum permissible burden to the whole body is 400 micro curies.

Safety Rules

  • Designate a specific area of the laboratory for all S-35 experiments.
  • All personnel who handle S-35 must wear full-length laboratory coats.
  • Many S-35 compounds readily penetrate gloves and skin. Wearing two pairs of gloves and changing the outer pair every 15 or 20 minutes will reduce the chance of contamination and absorption through the skin.
  • Pipettes dedicated for the use of S-35 should be used. These pipettes should not be used for other purposes as they are easily contaminated by S-35.

Laboratory Cleanup after Use

  • Conduct wipe tests using the liquid scintillation counter, checking all work areas and equipment used. Check the floor at the area where the isotope was used.
  • If any contamination is found, use a commercial radiation contamination remover such as Count Off, with paper towels, to clean the contaminated area.
  • Place the contaminated paper towels in a receptacle labeled as radiation waste.
  • If the contamination cannot be removed, label the area or equipment as radioactive, noting the isotope, the date of contamination and the maximum dpm found.
  • If any un-removable radiation is found, contact the University Radiation Safety Officer.
  • Check the normal trash container to ensure that no radioactive waste was placed there.
  • Store all radioactive waste in specially marked containers.
  • Send a Radiation Survey report to the University Radiation Safety Officer.