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122
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Department of Electrical Engineering Colorado State University Fort Collins. Colorado 80523
RECEIVED for review April 11, 1980. Accepted October 10, 1980. This research received generous financial support from the U S . Department of Energy and the Laramie Energy Technology Center. Reference to a trade name or product does not imply endorsement by the authors or by the US. Department of Energy.
'Present address: Paraho Oil Shale Corp. Grand Junction, CO 81501.
Krishnan Rajeshwar* Donald B. Jones' Joel B. DuBow
AIDS FOR ANALYTICAL CHEMISTS Purification of Cylinder Gases Used in Solvent Evaporation for Trace Analysis T. J. Nestrick' and L. L. Lamparski Analytical Laboratories, Dow Chemical U.S.A., Midland, M i c h g n 48640
Solvent-removal steps to effect residue concentration are commonly encountered in trace analytical procedures. When the compounds being determined are reasonably nonvolatile, the analyst is afforded some latitude in the method by which these concentrations may be accomplished. Two common approaches are the use of a Kuderna-Danish evaporative concentrator or a flowing stream of clean gas. The Kuderna-Danish system involves a classical fractional distillation, requires residue transfer to appropriate equipment, and is the more applicable system when dealing with larger solvent volumes (1-3). A flowing stream of clean gas can be advantageous in those cases where small volumes of volatile solvents (
