Hydrogen atom transfer in mass spectrometric fragmentation patterns of saturated aliphatic hydrocarbons

McCarthy, E.D.; Han, Jian; Calvin, Melvin

doi:10.1021/ac60266a021

Cited by 102 publications

(25 citation statements)

References 16 publications

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“…Their mass spectra were also compared with those of the NBS 75K.L and WILEY 138.L computer MS libraries. The structural assignments of internally methyl-substituted hydrocarbons were performed on the basis of the prominent mass ions C n H 2n + 1 and C n H 2n (McCarthy et al 1968) formed by the h-cleavage at the branch position(s). The 2-methylalkanes were fragmented to give a characteristic strong M-43 ion (loss of an isopropyl group) and a less intense M-15 peak (loss of a methyl group).…”

Section: Chemical Analysis Of the N-hexane Extractmentioning

confidence: 99%

Role of surface chemical signals in egg cannibalism and intraguild predation in ladybirds (Coleoptera: Coccinellidae)

Hemptinne¹,

et al. 2000

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Summary. The eggs of some ladybirds are known to be toxic to intraguild ladybird predators. However, this defence is of little value if the eggs are killed before their toxicity becomes apparent. The results presented in this paper indicate that chemicals on the surface of the eggs of two species of ladybirds signal the relative risk of cannibalism and intraguild predation. In Adalia bipunctata and Coccinella septempunctata, 87% of the chemicals are alkanes. Each species of ladybird is less reluctant to eat their own eggs than those of the other species. This asymmetry is to be expected because there is a greater risk to ladybirds from intraguild predation than cannibalism. Similar alkanes to those on the surface of the eggs of A. bipunctata are present in tracks left by larvae and on the elytra of the adults of this species. Those in the larval tracks deter females from ovipositing in patches of prey already being attacked by their larvae and those on the elytra are used in mate recognition. That different context dependent messages could be signalled by similar chemicals is an example of semiochemical parsimony.

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Section: Chemical Analysis Of the N-hexane Extractmentioning

confidence: 99%

Role of surface chemical signals in egg cannibalism and intraguild predation in ladybirds (Coleoptera: Coccinellidae)

Hemptinne¹,

et al. 2000

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“…The characteristics of mass spectral fragmentation patterns for the interpretation of methylalkane mass spectra were first elucidated by McCarthy et al [132]. The effect of the position of the methyl branch on the gas chromatographic elution of long-chain monomethylalkanes has been determined by Mold et al [133] and later by Szafranek et al [134].…”

Section: Structural Elucidation Of Insect Hydrocarbonsmentioning

confidence: 99%

Chemistry, biochemistry, and physiology of insect cuticular lipids

Blomquist

Nelson²,

Renobales

1987

Arch Insect Biochem Physiol

322

185

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The chemistry, biochemistry, and physiology of insect cuticular lipids are reviewed. The types of components present in cuticular extracts are described with special emphasis on the occurrence and identification of the di-and trimethylalkanes and the newly discovered tetramethylalkanes. The methods used in the extraction of cuticular components are discussed, including recommendations to standardize procedures. The structural elucidation of methylalkanes, particularly the mass spectral interpretation of multi-methylbranched alkanes, is reviewed. The biosynthesis of cuticular lipids is discussed with emphasis on the hydrocarbon components, describing elongation reactions and the origin of the methyl branches. The effects of environment and development on cuticular lipids are reviewed.

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“…The identification of saturated compounds was then confirmed by the injection of standard n-alkanes (from C 9 to C 40 ). The identification of the methyl position in branched alkanes was determined from the occurrence of C n H 2n+1 and C n H 2n fragments after α-cleavage at the branch positions [6].…”

Section: Methodsmentioning

confidence: 99%

Substrate Marking by an Invasive Ladybeetle: Seasonal Changes in Hydrocarbon Composition and Behavioral Responses

et al. 2013

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The multicolored Asian ladybeetle, Harmonia axyridis (Pallas), aggregates inside dwellings during the winter to survive the cold. Recent published reports have highlighted that overwintering individuals use hydrocarbon markings deposited on surfaces by conspecifics to orient toward aggregation sites. In the current study, monthly GC-MS analyses revealed seasonal modifications in the chemical profile of substrate markings deposited by moving individuals. The markings of overwintering ladybeetles contained larger proportions of heptacosadiene, nonacosadiene, hentriacontadienes, and methyl-nonacosanes, along with a lower proportion of heptacosene and nonacosene. This finding suggests the importance of the unsaturated and/or branched hydrocarbons in the H. axyridis aggregation process. Subsequently, we conducted behavioral assays to test whether (1) there is seasonal variation in the behavioral response of H. axyridis individuals toward substrate markings deposited by conspecifics in the same physiological state and (2) the observed behavioral modification is due to a change in ladybeetle sensitivity and/or a change in the chemical composition of the substrate marking. The results indicate that overwintering individuals exhibit a stronger “following” response toward conspecific substrate markings. This behavior is linked to both the physiological state of ladybeetles and the specific chemical profile of the marking biomolecules deposited under overwintering conditions.

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Hydrogen atom transfer in mass spectrometric fragmentation patterns of saturated aliphatic hydrocarbons

Cited by 102 publications

References 16 publications

Role of surface chemical signals in egg cannibalism and intraguild predation in ladybirds (Coleoptera: Coccinellidae)

Role of surface chemical signals in egg cannibalism and intraguild predation in ladybirds (Coleoptera: Coccinellidae)

Chemistry, biochemistry, and physiology of insect cuticular lipids

Substrate Marking by an Invasive Ladybeetle: Seasonal Changes in Hydrocarbon Composition and Behavioral Responses

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