I've decided to tackle Kilomentor's questions for an aspiring industrial/process chemist as an intermittent series. Some of these are fairly easy ("22. Norit, Darco and Nuchar are different types of what?")*, and some of them are quite complex ("8. What are polymorphs?")**
I'm particularly intrigued by Kilomentor's question 27: "What is swish TLC? When is it particularly useful?"He answers the question in an another post:
In this article the authors describe a purification technique for essentially pure chemical solids called informally in Merck Sharpe & Dohme laboratories “swishing”. Swish purification of several grams or several hundred grams of material is accomplished by overnight equilibration in a suitable solvent (an anti-solvent or very poor solvent actually), with magnetic stirring on a small-scale or with mechanical agitation in a Morton (creased) flask for large quantities. The technique is not readily applicable to small samples. Swishing is actually exhaustive equilibrium trituration.
Separating the trituration liquid from the residual solid results in a highly purified solid phase on the one hand and a solution in which many minor impurities are dramatically concentrated on the other. When thin-layer chromatography (TLC) is used to see the pattern and intensities of the impurities, the combined method is called Swish TLC.Kilomentor goes on to describe further uses of swish TLC, including the extraction and identification of low-concentration impurities. An intriguing technique -- I wish I'd thought of it! (And of course, like all intriguing techniques that you've never heard of, it was published long, long, long before I ever started thinking about chemistry.)
*Activated charcoal, in case anyone was wondering.
** That's a review article, not an interview question!