Reference

Column selectivity in high-performance liquid chromatography of substituted gem-dimethylcyclopropanes

Column selectivity in high-performance liquid chromatography of substituted gem-dimethylcyclopropanes. Abidi, S. L. (Natl. Fish. Res. Lab., U. S. Fish Wildl. Serv., La Crosse, WI 54602-0065, USA). J. Chromatogr., 368(1), 59-76 (English) 1986. CODEN: JOCRAM. ISSN: 0021-9673. DOCUMENT TYPE: Journal CA Section: 4 (Toxicology) HPLC sepn. of a series of gem-dimethylcyclopropanes was carried out in a variety of mobile phase and stationary phase systems. Comprehensive evaluation of column selectivity was made to identify chromatog. conditions under which various isomers could be resolved. In normal-phase HPLC on silica, retention data appeared to serve as good indicators for predicting relative polarity of the compds. in the solvent systems studied. For most cases, excellent baseline resoln. of cis-trans mixts. was attained. cis- [18383-59-0] And trans-chrysanthemol [18383-58-9] and cis- [7377-84-6] and trans-Et chrysanthemate [1802-02-4], however, were sepd. only with mobile phases of hexane [110-54-3] and hexane-isopropanol [67-63-0] (), resp. In reversed-phase HPLC, geometrical isomers of all but chrysanthemol were well resolved on octadecylsilica despite the poor selectivity of a propylphenylsilica column for these isomers under conditions used. The latter reversed-phase sepn. on propylphenysilica succeeded only in 2 cases (cis- [73367-05-2] and trans-RU-11679 [65167-05-7] and cis- [10453-56-2] and trans-resmethrin [10453-55-1]). Elution of cis and trans isomers in reversed-phase HPLC followed the same order as in normal-phase HPLC, except for the halogenated compds. where a reversal in elution order was obsd. Among chiral stationary phases studied, the chiral polymeric packings, poly(triphenylmethylmethacrylate) [30524-11-9] exhibited the highest selectivity for compds. contg. arom. groups on ester moieties. The halogen substituents in cis- [61949-76-6] and trans-permethrin [61949-77-7] and baythroid [68359-37-5] seemed to have adverse effects on the chiral recognition process. In HPLC on b-cyclodextrin [7585-39-9]-bonded silica, sepns. of diastereomeric (+)-cis- [34624-48-1] and (+)-trans-allethrin [28434-00-6], and cis- and trans-chrysanthemol demonstrated unique examples of unusual selectivity of b-cyclodextrin-bonded silica for isomers that virtually remained indiscernible by all other HPLC methods investigated. The percentage of b-cyclodextrin in the bonded phase had dramatic influence on the a values of certain isomeric pairs. Increasing the percentage b-cyclodextrin in the bonded phase somewhat favored the sepn. of some optical antipodes.

Three synthetic pyrethroids for control of Drosophila spp

Three synthetic pyrethroids for control of Drosophila spp. in wine cellars. Yerington, A. P. (Stored-Prod. Insects Res. Lab., ARS, Fresno, Calif., USA). J. Econ. Entomol., 70(4), 495-6 (English) 1977. CODEN: JEENAI. DOCUMENT TYPE: Journal CA Section: 5 (Agrochemicals) Resmethrin [10453-86-8] (0.5%), 0.175% d-trans-allethrin [28434-00-6], 0.015% RU 15525 [5-(phenylmethyl)-3-furanylmethyl (1R,3S,E)-3-[(dihydro-2-oxo-3[2H]thienylidene)methyl]-2,2-dimethylcycl opropanecarboxylate] [58769-20-3] and pyrethrins were equally effective in controlling Drosophila in a wine cellar. Cage tests with D. melanogaster gave similar results. All the insecticides, with the exception of resmethrin, were piperonyl butoxide [51-03-6]-synergized.