Mass fragmentographic determination of docosenoic acid in rapeseed oils

A highly sensitive and accurate reference method for determination of docosenoic acid (mainly erucic acid, 22∶1n−9) in different rapeseed oils is described. A fixed amount of [1-¹⁴C]erucic acid methyl ester (about 1 μg) is added to a fixed amount of oil. After treatment with sodium methoxide/methanol reagent and extraction with hexane, the amount of unlabeled erucic acid is determined from the ratio between the recordings at m/e 320 and m/e 322 obtained after analysis with a combined gas chromatograph-mass spectrometer equipped with an MID (multiple ion detector). The two ions used correspond to the M-32 peak in the mass spectrum of unlabeled and [1-¹⁴C]labeled erucic acid methyl ester. The relative standard deviation of the method is about 1.8%. The method was compared with a gas chromatographic method for determination of erucic acid.     

Determination of mono-, di-, and triglycerides by molecular distillation and thin-layer chromatography

Analysis of mixtures of mono-, di-, and triglycerides by molecular distillation and thin-layer chromatography is described. Mono- and diglycerides undergo appreciable acyl migration through the effect of heat during molecular distillation. Nevertheless this technique may be used for the quantitative analysis of mixtures of mono-, di-, and triglycerides, provided there are no substances present which catalyze, disproportionation. Thin-layer chromatographic (TLC) analysis of mono-, di-, and triglycerides is fast and simple and can be carried out on a micro-scale with a high degree of accuracy and precision. It also is extremely sensitive, permitting the quantitative estimation of as little as 0.1% of a single component in a mixture. This research was supported by the Hormel Foundation and General Foods Corporation, Tarrytown, N.Y. Presented at fall meeting, American Oil Chemists’, Society, New York, October 17–19, 1960.     

Reactions of dimethyl sulfoxide with sulfonate esters of fatty alcohols. I. Synthesis of higher saturated and unsaturated fatty aldehydes

Long-chain saturated fatty aldehydes (C₁₀ to C₁₈), as well as the C₁₈ unsaturated aldehydes (oleyl, linoleyl, and linolenyl), were synthesized in good yields by the selective oxidation of the sulfonate esters of the corresponding alcohols with dimethyl sulfoxide in the presence of sodium bicarbonate. Chromatographic procedures for the isolation of the pure aldehydes from the reaction mixtures are described. The purity of the aldehydes was ascertained by thin-layer chromatography, melting points of their 2,4-dinitrophenyl hydrazones, infrared spectra and other physical methods. Presented at the AOCS Meeting in Houston, April, 1965.     

Polyamine deactivation of integrated poly(dimethylsiloxane) structures investigated by radionuclide imaging and capillary electrophoresis experiments

The poly(dimethylsiloxane) (PDMS) material provides a number of advantageous features, such as flexibility, elasticity, and transparency, making it useful in integrated analytical systems. Hard fused-silica capillary structures and soft PDMS channels can easily be combined by a tight fit, which offers many alternatives for structure combinations. PDMS and fused silica are in different ways prone to adsorption of low levels of organic compounds. The need for modification of the inner wall surface of PDMS channels may often be necessary, and in this paper, we describe an easy and effective method using the amine-containing polymer PolyE-323 to deactivate both fused-silica and PDMS surfaces. The adsorption of selected peptides to untreated surfaces was compared to PolyE-323-modified surfaces, using both radionuclide imaging and capillary electrophoresis experiments. The polyamine modification displayed a substantially reduced adsorption of three hydrophobic test peptides compared to the native PDMS surface. Filling and storage of aqueous solution were also possible in PolyE-323-modified PDMS channels. In addition, hybrid microstructures of fused silica and PDMS could simultaneously be deactivated in one simple coating procedure.     

The parallel implementation of the one-dimensional Fourier transformed Vlasov-Poisson system

A parallel implementation of an algorithm for solving the one-dimensional, Fourier transformed Vlasov-Poisson system of equations is documented, together with the code structure, file formats and settings to run the code. The properties of the Fourier transformed Vlasov-Poisson system is discussed in connection with the numerical solution of the system. The Fourier method in velocity space is used to treat numerical problems arising due the filamentation of the solution in velocity space. Outflow boundary conditions in the Fourier transformed velocity space removes the highest oscillations in velocity space. A fourth-order compact Padé scheme is used to calculate derivatives in the Fourier transformed velocity space, and spatial derivatives are calculated with a pseudo-spectral method. The parallel algorithms used are described in more detail, in particular the parallel solver of the tri-diagonal systems occurring in the Padé scheme.

Program summary

Title of program:vlasovCatalogue identifier:ADVQProgram summary URL:http://cpc.cs.qub.ac.uk/summaries/ADVQProgram obtainable from: CPC Program Library, Queen's University of Belfast, N. IrelandOperating system under which the program has been tested: Sun Solaris; HP-UX; Read Hat LinuxProgramming language used: FORTRAN 90 with Message Passing Interface (MPI)Computers: Sun Ultra Sparc; HP 9000/785; HP IPF (Itanium Processor Family) ia64 Cluster; PCs clusterNumber of lines in distributed program, including test data, etc.:3737Number of bytes in distributed program, including test data, etc.:18 772Distribution format: tar.gzNature of physical problem: Kinetic simulations of collisionless electron-ion plasmas.Method of solution: A Fourier method in velocity space, a pseudo-spectral method in space and a fourth-order Runge-Kutta scheme in time.Memory required to execute with typical data: Uses typically of the order 10⁵-10⁶ double precision numbers.Restriction on the complexity of the problem: The program uses periodic boundary conditions in space.Typical running time: Depends strongly on the problem size, typically few hours if only electron dynamics is considered and longer if both ion and electron dynamics is important.Unusual features of the program: No     

Regio- and enantioselectivities in epoxide conjugations are modulated by residue 210 in Mu class glutathione transferases

The homologous human glutathione transferases (GSTs) M1-1 and M2-2 have similar catalytic activities with many electrophilic substrates, but differ strikingly in their conjugation of epoxides with glutathione. Residue 210, Thr in GST M2-2 and Ser in GST M1-1, is a key active-site component in determining the activity profile with epoxide substrates. This residue is hypervariable in Mu class GSTs, suggesting that it has special significance in the evolution of new functions. The present study shows that minor modifications of this residue can have major consequences for the enzyme-catalyzed epoxide conjugations. In general, a Ser at position 210 gives the highest catalytic efficiency, but the relatively high activity with an Ala placed on this position demonstrates that a hydroxyl group is not required. In contrast, a Thr residue suppresses the activity with epoxides by several orders of magnitude without major effects on the activity with alternative GST substrates. Residue 210 influences both the regio- and enantioselectivity with chiral and prochiral epoxides of stilbene and styrene and influences the distribution of isomeric glutathione conjugates. Thus, residue 210 contributes to both stereoselective recognition of the substrates and to partitioning of the isomeric reactants to the alternative transition states leading to separate chiral products.