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The synthesis and characterization of a variety of mesomorphic (liquid-crystalline) side-chain polysiloxane (MEPSIL) solvents, said to be useful as gas chromatographic stationary phases, are described and discussed. The synthetic scheme is based upon the hydrosilatlon reaction that occurs when 4-(allyloxy)benzoyl esters are contacted with poly(methylslloxane) In the presence of a dicyclopentadlenylplatinum(II) catalyst, while product characterization Is carried out by IR, NMR, GC, DSC, elemental analysis, and direct-observation hot-stage light-polarized microscopy. Selectivity of the MEPSIL phases Is shown to differ very substantially from those exhibited by all other common GC solvents. The MEPSIL found overall to be the best suited as a GC stationary liquid exhibits a melting point of 139 °C (k -n) and a nematic/isotroplc (n -*-I) transition temperature of 319 °C, while the practical operating limits of the material span 150 to in excess of 300 °C.The development and optimization of chromatographic techniques for maximal resolution in minimal time of analysis, coupled with maximum sample throughput, continue to represent a substantial problem when dealing with analytes comprised of structurally related isomers. Among the most notably difficult of these are polycyclic aromatic hydrocarbons (PAH) which are, at the very least, ubiquitous environmental pollutants produced by the incomplete combustion of organic matter. Moreover, some of the most efficient carcinogens known at present are members of, or products derived directly

Evidence for the existence of a male-produced aggregation pheromone secreted from the prothoracic femoral setiferous sex patch ofTribolium castaneum is reported. Both sexes were attracted toca. 60 ng of crude secretion. Males and females perceive the pheromone on the day of emergence while perception differs between the sexes: male response reaches a maximum on day 1 posteclosion, when tested at <1, 1, and 30 days; females show a maximum response at 30 days posteclosion. Behavioral responses to pheromone odors and a complex Chromatographic profile are reported.

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the reaction mixture with three aliquots of 0.250 ml of hexane, and concentrating the combined extracts gave recoveries of 92.1 ± 2.5% SEM ( = 12). This procedure gave a value for the Orchard Leaves of 2.41 ± 0.12 SEM ( = 6) which is 92.7% of