Determination of Normal Paraffins in C<sub>20</sub> to C<sub>32</sub> Paraffin Waxes by Molecular Sieve Adsorption. Molecular Weight Distribution by Gas-Liquid Chromatography

O'Connor, J. G.; Burow, F. H.; Norris, M. S.

doi:10.1021/ac60181a022

Cited by 141 publications

(19 citation statements)

References 9 publications

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“…Recovering 95% of the adsorbed alkanes by extraction with n-pentane required 17 days. Desorption was slower for long-chain alkanes than for short-chain alkanes [39]. Similar trends may be expected for polypropylene.…”

Section: Resultssupporting

confidence: 79%

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Adsorption of polypropylene from dilute solutions on a zeolite column packing

Macko¹,

Pasch²,

Denayer

2005

J. Sep. Science

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Faujasite type zeolite CBV-780 was tested as adsorbent for isotactic polypropylene by liquid chromatography. When cyclohexane, cyclohexanol, n-decanol, n-dodecanol, diphenylmethane, or methylcyclohexane was used as mobile phase, polypropylene was fully or partially retained within the column packing. This is the first series of sorbent-solvent systems to show a pronounced retention of isotactic polypropylene. According to the hydrodynamic volumes of polypropylene in solution, macromolecules of polypropylene should be fully excluded from the pore volume of the sorbent. Sizes of polypropylene macromolecules in linear conformations, however, correlate with the pore size of the column packing used. It is presumed that the polypropylene chains partially penetrate into the pores and are retained due to the high adsorption potential in the narrow pores.

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Section: Resultssupporting

confidence: 79%

“…It is known that desorption of alkanes from the narrow pores may be very difficult. For example, O'Connor et al [39] have described full adsorption of n-alkanes up to C 32 from isooctane at 758C in a zeolite with a pore diameter of 5 . Recovering 95% of the adsorbed alkanes by extraction with n-pentane required 17 days.…”

Section: Resultsmentioning

confidence: 99%

Adsorption of polypropylene from dilute solutions on a zeolite column packing

Macko¹,

Pasch²,

Denayer

2005

J. Sep. Science

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“…Sequential elution with hexane, 5% (vol/vol) cyclohexene in hexane, and diethyl ether yielded fractions containing alkanes, alkenes, and more polar compounds, in sequence. The alkane fraction in isooctane was then treated with 5-Å molecular sieves, resulting in adsorption of the straight-chain alkanes into the sieve matrix (34). Filtration or centrifugation of the resulting slurry gave a filtrate containing only branched-chain alkanes.…”

Section: Resultsmentioning

confidence: 99%

“…Crude extracts of insect cuticular lipids were first separated into straight-chain alkanes, methyl-branched alkanes, alkenes, and more polar compounds by known fractionation methods (32)(33)(34). Reverse phase HPLC with nonaqueous solvent systems and an evaporative light-scattering detector (ELSD), a "universal" detector that detects any nonvolatile molecule, then allowed isolation of individual components from these fractions.…”

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confidence: 99%

Isolation and determination of absolute configurations of insect-produced methyl-branched hydrocarbons

Bello¹,

McElfresh

Millar

2015

Proc. Natl. Acad. Sci. U.S.A.

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Although the effects of stereochemistry have been studied extensively for volatile insect pheromones, little is known about the effects of chirality in the nonvolatile methyl-branched hydrocarbons (MBCHs) used by many insects as contact pheromones. MBCHs generally contain one or more chiral centers and so two or more stereoisomeric forms are possible for each structure. However, it is not known whether insects biosynthesize these molecules in high stereoisomeric purity, nor is it known whether insects can distinguish the different stereoisomeric forms of MBCHs. This knowledge gap is due in part to the lack of methods for isolating individual MBCHs from the complex cuticular hydrocarbon (CHC) blends of insects, as well as the difficulty in determining the absolute configurations of the isolated MBCHs. To address these deficiencies, we report a straightforward method for the isolation of individual cuticular hydrocarbons from the complex CHC blend. The method was used to isolate 36 pure MBCHs from 20 species in nine insect orders. The absolute stereochemistries of the purified MBCHs then were determined by digital polarimetry. The absolute configurations of all of the isolated MBCHs were determined to be (R) by comparison with a library of synthesized, enantiomerically pure standards, suggesting that the biosynthetic pathways used to construct MBCHs are highly conserved within the Insecta. The development of a straightforward method for isolation of specific CHCs will enable determination of their functional roles by providing pure compounds for bioassays.T he use of chemical signals is highly developed within insects, with semiochemicals mediating a wide variety of inter-and intraspecific behaviors. Volatile pheromones, such as sex and aggregation pheromones, are the most well-known types, but insects also use nonvolatile cuticular lipids as contact pheromones (1-4). The cuticular lipids consist of a complex blend of n-and methyl-branched alkanes, alkenes, and lesser amounts of more polar compounds such as esters and alcohols. The lipid layer acts primarily as a waterproofing barrier (5), but individual lipid components have evolved secondary roles as signals that mediate a variety of behaviors and physiological changes (1, 2, 6). For example, solitary insects use cuticular hydrocarbons (CHCs) to identify the species and sex of mates (7, 8) whereas, in social insects, CHCs mediate identification of nestmates (9, 10), recognition of castes, and task allocation within the colony (11). Social insect queens also use CHCs to signal fecundity and dominance status within the colony, inhibiting development of workers into reproductives (12)(13)(14).Determining the roles of specific CHCs as signals has been hindered by three interlinked problems. First, CHCs typically consist of a large number of compounds, which can be difficult to isolate in pure form to test their bioactivities. Specifically, CHCs have very similar polarity and so are not separable by liquid chromatography on silica gel or other polar chromatographic m...

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“…absorption at 270mlJ. The nomlal alkanes were separated from branched-cyclic hydrocarbons with a sR molecular sieve (O'Connor et~., 1962). A 50:1 weight ratio of sieve to sample was used.…”

Section: Experimenta1mentioning

confidence: 99%

Hydrocarbon Constituents of Iceland Leaf Fossil

Han¹,

Calvin²

1970

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Determination of Normal Paraffins in C₂₀ to C₃₂ Paraffin Waxes by Molecular Sieve Adsorption. Molecular Weight Distribution by Gas-Liquid Chromatography

Cited by 141 publications

References 9 publications

Adsorption of polypropylene from dilute solutions on a zeolite column packing

Adsorption of polypropylene from dilute solutions on a zeolite column packing

Isolation and determination of absolute configurations of insect-produced methyl-branched hydrocarbons

Hydrocarbon Constituents of Iceland Leaf Fossil

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Determination of Normal Paraffins in C20 to C32 Paraffin Waxes by Molecular Sieve Adsorption. Molecular Weight Distribution by Gas-Liquid Chromatography

Cited by 141 publications

References 9 publications

Adsorption of polypropylene from dilute solutions on a zeolite column packing

Adsorption of polypropylene from dilute solutions on a zeolite column packing

Isolation and determination of absolute configurations of insect-produced methyl-branched hydrocarbons

Hydrocarbon Constituents of Iceland Leaf Fossil

Contact Info

Product

Resources

About

Determination of Normal Paraffins in C₂₀ to C₃₂ Paraffin Waxes by Molecular Sieve Adsorption. Molecular Weight Distribution by Gas-Liquid Chromatography