Gas chromatographic—mass spectrometric investigations of high-boiling crude oil alkane fractions

Chemistry, biochemistry, and physiology of insect cuticular lipids

“…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]. Nelson and Sukkestad [86] expanded on these approaches to methylalkane identification and used them to identlfy isomeric mixtures of long-chain mono-, di-, and trimethylalkanes in eggs of the tobacco hornworm, M. sextu.…”

Cuticular Hydrocarbons of the Colorado Beetle Leptinotarsa decemlineata say

“…The first two problems of Col orado beetle cuticular hydrocarbons are the subjects of the present study. During the study a capillary column with Dexsil 300 was used, which was earlier found to be the most efficient liquid phase for sep aration of isoalkane mixtures [11]. We believe this is true for the m ultibranched hydrocarbons as well.…”

“…They have been found to be odd (C29, C31, C33) and even (C30, C32, C34) carbon num ber hydrocarbons, with even and odd carbon num bers of the main chain. The positions of branching were at even (10 or 1 2 ) and odd (11,13,15,17) carbon num bers, respectively.…”

“…In this way 240 mg of a hydrocarbon mixture was obtained which constitutes 13% of the total lipid fraction. Hydrocarbons were separated by gas chrom atography (GC) on a 40 m capillary column with Dexsil 300 [11] (0.25 mm i.d., liquid phase film thickness 0.1 //m) or on a 40 m OV-1 capillary column. The separations were carried out with a Varian A erograph Model 1400 gas chrom ato graph, which had been modified for operation with a glass capillary column.…”