RESUMO
A procedure is reported for the selective ammonia chemical ionization of some nitrogen and sulfur heterocycles in petroleum fractions using ion trap mass spectrometry (ITMS). The ion trap scan routine is designed to optimize the population of ammonium reagent ions and eject from the trap (by radio frequency/direct current isolation) electron ionization products formed during reagent ion formation prior to ionization of the sample. The ITMS procedure is compared with standard ion trap detector and conventional quadrupole ammonia chemical ionization for the determination of nitrogen and sulfur heterocycles in gas oil and kerosine samples. Greatly enhanced selectivity is shown for the ITMS procedure by suppression of competing charge-exchange processes.
RESUMO
Certain olfactory cells of maleRhipicephalus appendiculatus Neumann are known to be stimulated by 2,6-dichlorophenol.R. appendiculatus has been reexamined for the presence of 2,6-dichlorophenol, and it has been detected in both male and female adults. Unfed females contain 12 ng/ tick, declining to 2 ng/tick after six days of feeding, while unfed males contain 2 ng/tick, falling to 0 after feeding. Larval tick extracts which are also known to stimulate 2,6-dichlorophenol-sensitive cells were examined and found to contain this phenol, whereasR. appendiculatus eggs did not contain this compound.
RESUMO
The principal compound which posseses trail-following activity at low concentration has been isolated from workers and from female alates of the grass feeding termiteTrinervitermes bettonianus. Male alates also produce the pheromone but in much smaller quantities than the female. The structure of the pheromone was determined as the diterpene hydrocarbon cembrene-A from spectra and microscale reaction data.
