A Pressure Source for Flash Chromatography The major problem associated with incorporating flash column chromatography' into the undergraduate laboratory is often the lack of a suitahle pressure source. Balloons2 and aquarium air pumps3 have been suggested to fill this need. Neither of these pressure sources provides enough pressure, by Jacobson's admission, to expel1 air from the adsorbent during column packing. Therefore, slurry packing must he used, and that detracts from the technique. We would like to suggest the use of a 50-mL plastic syringe (Aldrich 211,840-0, less than $1 ea.) as a n alternative simvle source ofuressure for flash ehromatomavhv. - . - We insert a plastic Y-tube into a one-hole rubber stonnerwhieh i6 fitted to the& ofa 20- x 400-mm column i~ornine38450-20) f o r to~ 1~-..e s a m ~ lsizes. e The svrinee , rip mnvrnientlg fir.+ snugly into one opening of rhp Y-rnhr, and n single thickness ofParafilm is moldpd o w r the orhcr and held in place bv slipping a shon p.rw of tuhing over it. The Parafilm acts as a prrrrure release valve and ruptures s t about 10 p.s.i. This method generates solvent drop rates up to 20 c m h i n as opposed to less than 4 cmlmin bv the other methods. This hieh flow rate does allow the standard uaekine.. ~ . m e e d u r eto be used. Since solvent eh'angeovrr can be done so qulckly at thcac flow ratra, wr h n w disco&ed the added henefit ofhwng ahle t o w e the samesil~ca~elbedseveral times forcenain srpnrorions hy during with nnrenlumn volumeofethyl acetate followed by one column volume of the e l u t i n ~solvent. We can supply .. . upon . request complete experimental details for the ferrocene-acetylferrwene and f l u o r e ~ e f l u o r e n o n eseparations. 7
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'Still, W. C.; Kahn, M.; Mitra, A. J Org. Chem. 1978,43,2922-2925. %ell, W . L.; Edmondson, R. D. J Chem. Educ. 1986,63,361. ?lacobson,0. M. J. Chem. Educ. 1988.65.459,
Josef G. Krause Niagara University, NY 14109
790
Journal of Chemical Education
