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7.28: Vacuum Sublimation

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     Detailed description is given in table 7.26
    Figure 7.14: Vacuum sublimation sequence.
    Table 7.26: Procedural summary for vacuum sublimation.

    Place the sample to be sublimed in the bottom of the sublimation apparatus.

    Lightly grease all joints.

    Use thick-walled tubing to attach to the vacuum arm, and apply the vacuum.

    The setup should not hiss or there is a leak.

    Fill the cold finger, or run water through the condenser.

    Be sure to apply the vacuum first, then coolant. If cooled before the vacuum, condensation may occur on the cold finger.

    Wave a heat gun or Bunsen burner on the apparatus to heat the sample.

    Sublimation should begin within a few minutes.

    Coax solid deposited on the side of the glassware toward the cold finger by waving the heat gun/burner on the sides of the glass.

    When the sublimation is complete:

    Remove the coolant.

    Allow the apparatus to come to room temperature.

    Delicately reinstate the air pressure, noting that an abrupt opening of the vessel will cause air to knock crystals off the cold finger.

    Remove the cold finger.

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