Chromatographic separation of the pyrethrins

Abstract

‘Pyrethrins’ I and II have been separated on both alumina and silica columns. On alumina columns there is some evidence of the separation of the cinerins from the pyrethrins. Material separated in this way has been used to elucidate separations obtained by chromatography of pyrethrum extracts on paper impregnated with alumina and by paper chromatography of 2: 4‐dinitrophenylhydrazine derivatives of the ‘pyrethrins.’.

Estimation of Micro Quantities of Pyrethroids

“…Although the extraction of pyrethrins and of allethrin from flour and of pyrethrins from paper or cotton bags did not present any particular problem in most cases, the extraction of allethrin from these wrapping materials presented problems which could be explained and at least partly solved only by a consideration of the physical problems of adsorption as encountered in chromotography. At the present time the nature of these problems, apparently based mainly on irreversible adsorption, has been recognized but the difficulties have not been completely overcome, as, for example, in the attempts at a chromatographic separation of p\-rethrins and of their degradation and reaction products (10,19).…”

Chromatographic 2,4-Dinitrophenylhydrazone Method for Determination of Allethrin

“…Some impurities, such as allethrolone, form bands which easily separate from the main band. Although Lord et al (15) and Oiwa et al (17) mention dinitrophenylhydrazones of pyrethrins, no method has been developed nor have adequate conditions been given for the formation of the dinitrophenylhydrazones of pyrethrins or allethfin; and their formation in high yield is a critical matter. The authors' 2,4-dinitrophenyllrydrazone procedure has certain advantageous features, such as utilization of the entire allethrin molecule rather than just the acid formed on cleavage, the formation of a colored derivative which can be chromatographed, the use of small samples, and the fact that acidic impurities need not be determined separately.…”

Insecticide Assay, Chromatographic Separation of Active Components of Natural Pyrethrins and Their Characterizations

“…Enriched "PI" (mixture of PI and Cl) and "PII" (mixture of PII and CII) have been obtained by repeated liquid-liquid partitions (8,20,27). "PI" and "PII" have also been separated by paper (19,29) and column chromatography (6,10,17,18,22). Ward (25) and later Brown and The constituents of concentrated pyrethrum extracts were fractionated on a preparative scale by chromatography on Celite, silicic acid, and charcoal columns.…”