Articles & Tech Notes
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The Challenge Of Mixed Solvents
This month, we are discussing a complex problem that is becoming more and more prominent because of the chemistries specified and the ways of working that are being adopted by many users of evaporation equipment. We’re principally concerned with mixtures in which there is one volatile component and one high boiling point solvent. An example might be methanol /DMSO, or THF/pyridine. What's more, the two solvents don’t have to be within the same sample. A rack of tubes where each tube contains a different single solvent, will also exhibit the effect described below. Frequently a user who wishes to remove methanol/DMSO will not even mention the methanol when specifying the application, because methanol is “easy” and it’s the DMSO that is considered the challenge. However, this overlooks a rather important technical issue that we will deal with here.