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IZeccivctl October 24, 18G1 \'nrious porphyrins ant1 chlorophyll tlerivatives have been purified on a preparative scale by tlistribution between hydrochloric acid and ether on Celite columns. By this technique C I. L I ~ C Clz101.obi~i~1~ pheophorbide (650) was resolved into six components, which possessed almost identical visible absorption spectra, but slightly different acid distribution numbers. Chromic acid oxidation and subsequent gas-liquid partition chromatography of the neutral fractions indicate the prcscncc of more than one Chlorobi.z~?la chlorophyll (G50) in the original pipnie~lt preparation. The methocl most frequently used for resolving mixtures of porphyrins or chlorophyll clerivatives is partition between aqueous hydrochloric acid and ether. The resolution obtained b!, this methocl depends on how inuch the colnpounds differ in basicity and solubility. A11 approxiinate quantitative expression of these properties is the "acid number", i.e. the percentage (w/w) of aqueous hydrocl~loric acid which extracts two thirds ot a cornpound from an equal volume of ether (1). When the "acicl numbers" of two pigniei~ts differ by several percentage units complete separation lllay be readily accomplishecl. However, when coinponents possess alrnost equal "acid numbers" counter-current-distribution is usually necessary. This method has the disadvantages of requiring special, expensive apparatus and is not usually applicable t o large quantities of material. Licluicl-liquid partition chromatography has been applied in a few instances to the resolution of mixtures of porphyrins (2, 3, 1). In particular, Fall; (5) has quoted the use by Scott of Celite columiis containing hydrochloric acid as the stationary phase and ether as the eluent. No experin~ental details have, to our Itnowledge, been published. We have developed such a procedure and have found that by choosing the appropriate strength of hydrochloric acid or by using solvents other than ether, many mixtures of porphyrins and chloropl~yll derivatives of similar acid number can be resolved. Our experience fully confirins that of Leinieux et al. (6) concerning the ease of co~istruction and extrusion of Celite columns, and of uniform and rapid flow through such columns.

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