Ice is nice

Your article about a refrigerated condenser for rotary evaporators, or rotovaps, describes a very useful invention for minimizing the use of laboratory dry ice and tap water (C&EN, Feb. 1, page 22). I applaud George Adjabeng for developing this apparatus, and I wish him well in this venture.

The article, however, did not mention that for much of the routine use of rotary evaporation there is an obvious and cost-effective alternative to both dry ice and tap water. That alternative is ice. In the organic chemistry teaching and research laboratories at Indiana State University, we have equipped our rotovaps with cold-finger (“dry ice”) condensers rather than the more commonly used spiral glass tube (“tap water”) condensers, but instead of filling the cold fingers with dry ice, we fill them with regular ice from a laboratory ice machine.

We began phasing in these condensers in the 1990s as a way to save water, and we have been very satisfied with the results. For example, there is certainly no need for us to ever be concerned about cooling water being left running overnight. On those rare occasions when we need a lower temperature, the rotovaps are already equipped to handle dry ice.

Richard Kjonaas
Terre Haute, Ind.