Thin layer chromatographic separation of common analgesics-a

Thin Layer Chromatographic Separation of Common Analgesics-A

Comment

In a recent issue' a laboratory procedure describing a tlc ~rocedurefor separatinganalgesics was reported. This type of experiment is reported in a t least four laboratory manual~.~-s In the recent report, utilizing a three component solvent system, the authors were unable to resolve phenacetin and salicvlamide. In the oroeedure bv Adams. Johnson and Wilcox. all of the analeesics are resolved usine- a two comoonent solvent svstem 11.2-dichloroethane-aeeticacid). ~. , I'at in, l.nmpnmn, and K r n sugarit the ilmplrsl rolvent y s t r m iethyl 3CPI,ll(.I n hich dues not T C S I ~ Wthe :walge-ic* phrnacrttn, a n l q Inmid*, and ;aspirm The latter tr..> are c a d y disfingu~~hialde *inre i n h y l i l n ~ i di i~I ~ U O I P ~ ( C ~whdc I aspirin is not. Using the procedure by Auk or Moore and Dalrymple which requires a four component solvent system, again it is not possible to resolve aspirin and salicylamide. We have carried out the tlc separation of analgesicsin our sophomore organic laboratory with a variety of solvent systems and commercially available silica-gelplates. Of the procedures reported above we have had the best results with that of Adams e t al. ~

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Philadelphia,'!976. "dams, R., Johnson, J. R., and Wilcox, Jr., C.F., "Laboratory Experiments in Organic Chemistry," 7th Ed.. Macmillan, New York, 1979. Auk, A., "Techniques and Experiments for Organic Chemistry" 2nd Ed., Holhrook, Boston, 1976. Moore, J. A., and Dalrymple, D. L., "Experimental M e t h d s in Organic Chemistry" 2nd Ed., W. B. Saunders, Philadelphia, 1976.

D. F. Roswell N. M. Zaczek Layala College Baltimore, MD 21210

834 / Journal of Chemical Education