Andrew J. Gellman Group S.O.P.
Transfer and Purification of Chemicals
Transfer of chemicals
- Accidental skin or eye contact with chemicals is possible during the transfer process. Consult the MSDS for the involved chemical should this occur. In case of contact with hazardous compounds or large spills, contact campus security at 8-2323 and/or Environmental Health and Safety at 8-8182.
- All transfer operations should be conducted under a fume hood.
- Review the appropriate MSDS before transferring any chemical.
- Always use gloves and chemical goggles when transferring any chemical.
- Verify that the fume hood is operational before starting to transfer chemicals.
Purification of chemicals (freeze-pump-thaw)
- Prepare a clean vial by washing it with the appropriate solvent. O-rings for the sample vial valve may also need to be changed. Remove solvent by connecting the vial to the vacuum manifold in B207. A heat gun may be used to speed the evaporation of the cleaning solvent.
- After pumping away the cleaning solvent, close the valve on the sample vial. The vial should be clean and under vacuum.
- Prepare a clean pipette or syringe to transfer the chemical.
- Disconnect the vial from the vacuum manifold.
- Using the pipette or syringe, transfer the desired amount of the chemical from the original container to the upper part of the sample vial.
- Slowly open the valve to the lower part of the sample vial. Do not let all of the chemical flow into the bottom of the vial. Do not allow any air to flow into the bottom of the vial. Close the sample valve while leaving a small amount of the chemical in the upper part of the vial. This minimizes the amount of air contamination in the sample. Dispose of excess chemical from the upper part of the vial in the appropriate waste container.
- Connect the vial filled with chemical to the vacuum manifold. Open the valve between the manifold and the sample vial to pump the air from the top of the sample vial. At this point, the valve on the sample vial remains closed. Prepare liquid nitrogen in a small container (a Styrofoam coffee cup works well).
- Submerge the sample vial in liquid nitrogen until the chemical freezes. Open the valve to the vial for 5-10 seconds and then close the valve. Notice the pressure rise in the manifold as non-condensible gases are pumped away from the frozen sample.
- Remove the liquid nitrogen and allow the chemical to thaw.
- Repeat this process until the pressure rise after opening the sample vial valve during step 2 is negligible.