B. V. Burger

Headspace gas analysis : quantitative trapping and thermal desorption of volatiles using fused-silica open tubular capillary traps

Abstract A system has been devised with which volatiles can be effectively trapped from headspace gas samples at relatively high flow-rates. Material is trapped in fused-silica capillary traps, 1 m in length, and coated with either an immobilized SE-30 layer, or a suitable adsorbent such as activated carbon or a powdered porous organic polymer supported on immobilized SE-30. These fused-silica traps are installed and used in stainless-steel tubes (desorption tubes) through which an electrical current is passed to effect on-line thermal desorption of the trapped volatiles. Thermal conversion of labile compounds such as α-pinene and γ-terpinene can be avoided by temperature-programmed or -controlled desorption in conjunction with cold trapping of the desorbed volatiles on the capillary column. The capacity of different traps was compared for a number of compound types and their versatility demonstrated by carrying out headspace gas determinations on, for instance, wine, urine and an imitation fruit drink.

Avian exocrine secretions. I. Chemical characterization of the volatile fraction of the uropygial secretion of the green woodhoopoe, Phoeniculus purpureus

Using gas chromatography–mass spectrometry in conjunction with auxiliary techniques such as solid phase microextraction and determination of double bond positions by means of dimethyl disulfide derivatization, 45 constituents of the uropygial secretion of the green woodhoopoe, Phoeniculus purpureus, have been identified. The majority of these constituents are long-chain branched and unbranched alkanes, and (Z)-alkenes such as (Z)-9-tricosene, and a number of unidentified wax esters. The more volatile fraction of the secretion contained short-chain fatty acids, aldehydes, aliphatic and heterocyclic aromatic amines, ketones, and dimethyl sulfides. This group of volatile compounds is responsible for the obnoxious odor of the secretion and also for its defensive action against predators.

Lizard Epidermal Gland Secretions I: Chemical Characterization of the Femoral Gland Secretion of the Sungazer, Cordylus giganteus

The giant girdled lizard or sungazer, Cordylus giganteus, is endemic to South Africa. It has been suggested that in this species, as in other lizard species, epidermal glands in the femoral, pre-cloacal regions, and cloacal glands are the main sources of semiochemicals and that these secretions could play an important role at different levels of the social biology of the animals. To gain a better understanding of the nature of the femoral gland secretions of the sungazer, characterization of the constituents of the secretions was carried out. By using GC-MS analysis, in conjunction with auxiliary techniques, such as solventless sample introduction and trimethylsilyl derivatization, 53 relatively involatile compounds, including carboxylic acids, alcohols, ketones, esters, and steroids, were identified in the secretions of both sexes. The study showed that the secretions of male and female sungazers contain only semi-volatile chemicals.

Mammalian exocrine secretions. XII: Constituents of interdigital secretions of bontebok, Damaliscus dorcas dorcas, and blesbok, D. d. phillipsi

In addition to the nine compounds identified in the interdigital secretion of the bontebok, Damaliscus dorcas dorcas, in a previous study, 76 compounds belonging to different compound types, were identified in the interdigital secretions of the bontebok and the blesbok, D. d. phillipsi. These compounds include alkanes, alcohols, aldehydes, ketones, fatty acids, terpenoids, γ-lactones, an isopropyl ester, long-chain hydroxyesters, 2-substituted pyridines, phenols, steroids, and dimethylsulfone. No qualitative differences were found between secretions from the two sexes or from animals from different habitats. Although no attempt was made to correlate territorial behavior or other behavioral phenomena with the qualitative composition of interdigital secretions from individual animals, available information seems to indicate that quantitative differences probably do not have a major semiochemical function. Only two species of bacteria, Bacillus brevis and Planococcus citreus, were found in the interdigital pouches of male and female members of the two subspecies, regardless of the habitat of the animals. B. brevis synthesized, among other unidentified constituents, (Z)-3-penten-2-ol, 2-hexanone, 2-octanone, 2-nonanone, tetradecanoic acid, pentadecanoic acid, heptadecanoic acid, octadecanoic acid, (Z)-9-hexadecenoic acid, and isopropyl hexadecanoate in vitro, while P. citreus produced, among others, the γ-lactones dodecan-4-olide and (Z)-6-dodecen-4-olide, which is one of the major constituents of the interdigital secretions of both subspecies. Some components of the interdigital secretions are not present in the interdigital glandular tissue, and the possibility is discused that these compounds could be produced by microbiological activity in the interdigital pouch.

Semiochemicals of the Scarabaeinae: VI. Identification of EAD-Active Constituents of Abdominal Secretion of Male Dung Beetle, Kheper nigroaeneus

Using gas chromatography with flame ionization detection (FID) and electroantennographic detection (EAD) in parallel, and employing chiral and achiral capillary columns, three constituents of the abdominal sex-attracting secretion of male Kheper nigroaeneus dung beetles were found to elicit reproducible EAD responses in male and female K. nigroaeneus antennae. One of these constituents is present in the secretion in such a small quantity that it could not be detected by FID, and it was not identified. The other constituents were identified as 3-methylindole (skatole) and (R)-(+)-3-methylheptanoic acid.

Production and use of capillary traps for headspace gas chromatography of airborne volatile organic compounds

Abstract The production of adsorption traps with activated charcoal particles embedded on the inside surface of glass capillary tubes and of capillary traps contianing thick (10–15 μm) ultra-thick (145μ) filmes of an apolar stationary phase is described. The application of these traps to the headspace detection of organic volatiles in various gas samples and in air and the problems involved in the use of these traps are discussed.

Semiochemicals of the Scarabaeinae. VII: Identification and Synthesis of EAD-Active Constituents of Abdominal Sex Attracting Secretion of the Male Dung Beetle, Kheper subaeneus

Using gas chromatography with flame ionization detection (FID) and electroantennographic detection (EAD) in parallel, butanoic acid, skatole, and (E)-2,6-dimethyl-6-octen-2-ol were identified as constituents of the abdominal sex-attracting secretion of the male dung beetle, Kheper subaeneus, which reproducibly elicited EAD responses in male and female antennae. This is the first report of the occurrence of (E)-2,6-dimethyl-6-octen-2-ol as a natural product, for which the name (E)-subaeneol is proposed. In some experiments, a few other constituents of the secretion also gave reproducible responses in specific male and female antennae but did not elicit responses when the analyses were repeated with other antennae. The major volatile constituent of the secretion, identified as (S)-(+)-2,6-dimethyl-5-heptenoic acid, is one of these EAD-active compounds. Both this compound and (E)-2,6-dimethyl-6-octen-2-ol were synthesized from authentic starting materials for comparison with the natural products.

Constituents of wing gland and abdominal hair pencil secretions of male African sugarcane borer,Eldana saccharina walker (Lepidoptera: Pyralidae).

In addition totrans-3,7-dimethyl-6-octen-4-olide (eldanolide), vanillin, and 4-hydroxybenzaldehyde, identified by French workers in the wing gland and abdominal hair pencil secretions of the male African sugarcane borer,Eldana saccharina, we have, in an earlier note, reported the presence of several other terpenoid, aromatic, and unbranched-chain compounds such as, (Z)-3,7-dimethylocta-2,6-dienoic acid, 6,10,14-trimethyl-2-pentadecanol, 4-hydroxy-3-methoxybenzyl alcohol, 1-octadecane thiol, 16-hexadecanolide, and 18-octadecanolide in these secretions. In the present paper experimental details and spectral evidence supporting the identification of these compounds, as well as the identification of (Z)-9-hexadecenal and cw-3,7-di-methyl-6-octen-4-olide (cis-eldanolide), are reported. Using electroantennography it was found that male and female antennae reacted approximately equally strongly to both secretions. This result was confirmed in analyses of the secretions using coupled gas chromatography-electroantennography and it was found that male as well as female antennae responded to eldanolide. Vanillin, substituted phenols related to vanillin, and some oxygenated monoterpenes elicited weak responses in male and female antennae. In some analyses 6,10,14-trimethyl-2-pentadecanol, present in the secretions of the insect, gave a strong antennal response. The results obtained in dynamic and static headspace determinations showed that several of the organic compounds present in the glandular secretions are released in detectable quantities and are present in widely varying quantitative ratios in the effluvia of individual calling male moths.

Chemical constituents of the chest gland secretion of the thick-tailed galago (Galago crassicaudatus)

The naturally exuded chest gland secretions of adult male and female thick-tailed bush babies were collected directly in capillary tubes. The pure secretion was subjected to GC-MS analysis which revealed three major components. These were identified by comparison with the appropriate standard compounds: benzyl cyanide,p-hydroxybenzyl cyanide, and 2-(p-hydroxyphenyl)ethanol. Analysis of a male and a female secretion indicated that some sexual dimorphism in the relative concentrations of these components may exist.

Mammalian exocrine secretions : X. Constituents of preorbital secretion of grysbok, Raphicerus melanotis

Using electron impact and chemical ionization mass spectrometry with methane and nitric oxide as reactant gases in conjunction with mass spectral analysis of the dimethyl disulfide derivatives of unsaturated constituents, 51 compounds have been identified in addition to the compounds previously found in the preorbital secretion of the grysbokRaphicerus melanotis. The compounds identified are saturated, monounsaturated, and diunsaturated alcohols and formates, saturated and monounsaturated aldehydes, saturated carboxylic acids,γ- andδ-lactones, alkyl methyl sulfides, andβ-hydroxyalkyl acetates. All of these compounds have unbranched structures. The constituent previously incorrectly identified as (Z)-5-tetradecen-1-ol, was found to consist of the coeluting (Z)-7- and (Z)-8-tetradecenols.