Stereoisomeric Analysis of 6,10,14-Trimethylpentadecan-2-ol and the Corresponding Ketone in Wing Extracts from African Bicyclus Butterfly Species
Gas chromatography (GC) and mass spectrometry (MS) were used to determine the stereoisomeric compositions of 6,10,14-trimethylpentadecan-2-ol and 6,10,14-trimethylpentadecan-2-one in wing extracts from 17 Bicyclus butterfly species from different regions of Africa. All samples were purified using solid phase extraction (SPE). Since some species contained both alcohol and ketone, these were separated and the ketone was reduced to the alcohol before analysis as either (R)-trans-chrysanthemoyl or (S)-2-acetoxypropionyl esters. A novel asymmetric synthesis was developed for a reference mixture of (2R/S,6S,10R)-6,10,14-trimethylpentadecan-2-ol with known composition of the eight stereoisomers. The mixture then was used as the (R)-trans-chrysanthemoyl esters to correlate each of the eight gas chromatographic peaks to a specific stereoisomer of the extracted wing compounds. Seven butterfly species showed (2R,6R,10R)-configuration of the alcohol, four species contained minute amounts of alcohol too small to determine the stereochemistry, nine species showed (6R,10R)-configuration of the ketone, and one species contained minute amounts of ketone too small to determine the stereochemistry. No other stereoisomers of alcohol or ketone could be detected in the extracts, and the quantities of the compounds in the wing extracts varied from 5 to 900 ng per sample for each species.
In vivo real-time monitoring of aphrodisiac pheromone release of small white cabbage butterflies (Pieris rapae).
The study of insect behavior is of practical importance for developing possible control methods in Integrated Pest Management. Currently, one model of butterfly mating behavior suggests that the initial location of potential mates occurs visually followed by the release of one or more short-range male aphrodisiac pheromones. This model is supported by data obtained from field observations and inferences based on the behavioral effects of chemicals extracted or isolated using indirect and offline techniques. In this study, we performed in vivo real-time monitoring of the male aphrodisiac pheromones released by the small white cabbage male butterfly (Pieris rapae Linnaeus) using confined direct analysis in real time (cDART) mass spectrometry. cDART is a new method easily adapted to the study in real time of chemicals released into the environment by virtually any insect. The major compound released by the male Pieris rapae was identified as ferrulactone. The experimental results reported here indicate that the release of ferrulactone occurs less than 1s after the male visualizes its partner, and reaches a maximum after about one half minute. This study is the first reported in vivo detection and monitoring of butterfly male aphrodisiac pheromones in real time.
Dating of Historical Manuscripts Using Spectrometric Methods: A Mini-Review
An overview is provided of spectrometric methods useful for age estimation of historical manuscripts (medieval ones in particular), in order to confirm their authenticity. Individual methods (infrared and Raman spectroscopy, mass spectrometry, atomic emission spectroscopy, X-ray spectroscopy, and electron scanning microscopy) are discussed and examples of their application described. The following general strategy can be recommended for dating and/or authenticating of historical manuscripts. First of all, the pigment analysis should be carried out using Raman spectroscopy (distinguishing the period and modern pigments), followed by PIXE ink analysis (solving the question of ink homogeneity). Finally, the radiocarbon dating of the writing support, potentially supplemented by the ink dating using scanning Auger microscopy should be performed.