University of Vermont

P-32 SOP

STANDARD OPERATING PROCEDURES

Phosphorus-32


revised: November 5, 2004

INTRODUCTION

Phosphorus-32 is a commonly used radionuclide with a half-life of 14.3 days, emitting beta particles with a maximum energy of 1.71 MeV (Million Electron Volts). The beta particles travel a maximum of 20 feet in air. See Appendix A for information on the rate at which P-32 decays.


CONCERNS

The major concerns with using P-32 are:

  • Surface radiation exposure to the skin of the hands. A drop of contamination containing 1 microcurie of P-32 on 1 cm2 area of the skin produces a radiation dose of 6,000 millirems / hour.

    This means that the quarterly NRC limit of 12,500 millirems to the skin would be reached in 2 hours and 5 minutes and the annual NRC limit of 50,000 millirems would be reached in just 8 hours and 20 minutes.

    One microcurie = 2.22 x 10E6 dpm (disintegrations per minute)

  • Radiation exposure in air over an open vial. The dose rate at the opening of a vial containing 1 millicurie of P-32 can be as high as 26,000 millirems per hour.

    This means that the quarterly NRC limit of 12,500 millirems for the hands would be reached in 28 minutes.

  • Working with P-32 orthophosphate in high concentrations. Using orthophosphate poses significant problems because of the large activity and high concentrations (i.e., 5 millicuries in 10 lambda !). If you can avoid using them, please do so.

    Our experience at UVM has shown that laboratories using pre-labelled P-32 (dATP, dCTP, ATP, etc.) in activities of 0.25 and 0.5 millicuries have had little or no safety problems.

    Using lower concentrations is very desirable. Most companies will provide lower concentrations if requested. The cost of using pre-labelled materials or lower concentrations is higher but the return in safety more than offsets the additional cost.


    SHIELDING

    Plexiglass (lucite) is the best shield for beta particles from P-32. When more than 1 millicurie of P-32 is handled, a sufficient number of x-rays (bremmstrahlung) may be formed to require Lead foil to be added to the exterior of the shield. The beta particles travel a maximum of 3.1 mm. in glass, 6.7 mm. in lucite, and 8 mm. in tissue.

    DETECTION

    A tiny drop of contamination of P-32 can be easily detected with a Geiger Counter.

    EQUIPMENT / SUPPLIES

    The following equipment and supplies must be available:
    • A Geiger Counter sensitive to beta particles
      • We recommend the Ludlum Model 3 or an equivalent with a pancake style G-M detector. Also, another excellent survey meter is Ludlum Model 3-98 which will not only detect the beta particles from P-32 but also the bremmstrahlung (secondary x-ray) radiation.
    • 3/8" or 1/2" plexiglass benchtop shield.
      • These are available from many lab equipment vendors such as RPI, VWR, Fisher, etc. and cost $150 -$250. The Instrument Model Facility (IMF) Office at UVM can also custom make one for you.
      • If you are going to handle more than 1 millicurie, we recommend the 1/2" thickness.
    • disposable latex or plastic gloves.
    • Film badge and ring badge.
    • full-length lab coat.
    • plexiglass containers for radioactive waste.
      • These are available from many lab equipment vendors such as RPI, VWR, Fisher, etc.
    • pipettes dedicated to the use of P-32.
    • plastic safety glasses.
    • commercial decontaminate, i.e. DuPont's "Count Off".

      SAFETY RULES

      If the following safety rules are followed, personnel radiation exposure will be as low as reasonably achievable.
      1. Designate a specific area of the lab for P-32 handling.
        • Place the plexiglass shield near a wall (not toward another work area on the other side of the bench) away from the main flow of traffic in the lab.
      2. All persons handling P-32 must wear a ring badge on the hand which is most frequently used to handle vials, samples, pipettes, etc. containing P-32.
      3. Full-length lab coats must be worn by all persons who handle P-32.
      4. Protect the skin of your hands from becoming contaminated by wearing two pairs of disposable gloves.
      5. A Geiger counter must be in operation during the experiment, and at other times.
        • To avoid contaminating the detector, place a thin sheet of plastic (i.e., Saran Wrap) around the detector
      6. Place all vials and test tubes containing P-32 behind a 3/8" or 1/2" thick plexiglass shield.
        • Check the radiation level in front of the shield to determine if Lead foil should be added to block out the x-rays (called bremstrahlung) formed by the beta particles interacting with the plexiglass.
      7. Do not work directly over an open container of P-32.
      8. Never pipette P-32 by mouth.
      9. Only use pipettes which have been dedicated to your specific use of P-32.
        • Pipettes will easily become contaminated and should be checked frequency and therefore, should not be shared with others.
      10. Use the Geiger Counter to check your gloves frequently for contamination.
        • If contamination is found, immediately dispose of the gloves in the radioactive waste container

    POST-USE PROCEDURES

    After handling P-32,
    • Use the Geiger Counter to check your hands, shoes, clothing, work bench, floor, centrifuges, and water baths for contamination.
    • If any contamination is found on your shoes and/or clothing, contact the RSO. You will likely have to remove it temporarily to clean or store until the radiation decays to background.
    • If any contamination is found on your hands, wash thoroughly with soap and water. This will usually be sufficient to remove the surface contamination. If it does not, contact the RSO for assistance.
    • If any contamination is found on the work bench, floor, or lab equipment, use a commercial radiation contamination remover (i.e. Count Off) with paper towels to clean up the equipment. Place the towels in the radioactive waste receptacle.
    • If contamination cannot be removed, place a "radiation" label on the equipment indicating that it is P-32, maximum cpm found, and the date you measured the level.
    • If contamination cannot be removed from the floor, contact the RSO to obtain shielding materials.
    • Inform your fellow lab workers if any unremovable contamination is found.
    • Check the normal trash container to make sure no radioactive waste has been accidentally placed there.
    • Store the waste temporarily in plexiglass containers or other containers which are sufficient to absorb P-32's beta particles.
    • Send a Radiation Contamination Survey Report to the RSO.
    • Call the RSO if you have any questions about where to survey, or how to fill out the form.
    • Wash your hands thoroughly after using P-32.
    • Bring the waste to the RSO frequently. Do not let it pile up. The RSO accepts waste every Friday. Call 656-2570 for an appointment.

    º Any questions about these procedures ? Call the Radiation Safety Office, 656-2570 º

    APPENDIX A

    DECAY RATE OF P-32

    Days Elapsed-----Activity Remaining------Decay Factor 
    • 0----------------------100.0 ------------------1.00
    • 1---------------------- 95.3 ------------------0.953
    • 2---------------------- 90.8 ------------------0.908
    • 3---------------------- 86.5 ------------------0.865
    • 4---------------------- 82.4 ------------------0.824
    • 5---------------------- 78.5 ------------------0.785
    • 6---------------------- 74.8 ------------------0.748
    • 7---------------------- 71.2 ------------------0.712
    • 8---------------------- 67.8 ------------------0.678
    • 9---------------------- 64.6 ------------------0.646
    • 10---------------------- 61.6 ------------------0.616
    • 11---------------------- 58.7 ------------------0.587
    • 12---------------------- 55.9 ------------------0.559
    • 13---------------------- 53.2 ------------------0.532
    • 14---------------------- 50.7 ------------------0.507
    • 15---------------------- 48.3 ------------------0.483
    • 16---------------------- 46.0 ------------------0.460
    • 17---------------------- 43.8 ------------------0.438
    • 18---------------------- 41.8 ------------------0.418
    • 19---------------------- 39.8 ------------------0.398
    • 20---------------------- 37.9 ------------------0.379
    • 21---------------------- 36.1 ------------------0.361
    • 22---------------------- 34.4 ------------------0.344
    • 23---------------------- 32.2 ------------------0.328
    • 24---------------------- 31.2 ------------------0.312
    • 25---------------------- 29.7 ------------------0.297
    • 26---------------------- 28.3 ------------------0.283
    • 27---------------------- 27.0 ------------------0.270
    • 28---------------------- 25.7 ------------------0.257
    • 29---------------------- 24.5 ------------------0.245
    • 30--------------------- 23.3 ------------------0.233
    • :---------------------------------------------------
    • 143 (10 half-lives)------ 0.1 ------------------0.001
      For example, if your vial contained 500 microcuries of P-32 on 7/1/04, the amount of activity remaining on
    • 7/8/04 (7 elapsed days) would be:
                   Activity   x  Decay Factor 
                = 500 microcuries x 0.712 = 356 microcuries

Last modified November 05 2004 03:04 PM

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