Gas-liquid chromatographic analysis of cyclopropenoid fatty acids

A method is described for the analysis of cyclopropenoid fatty acids in oils. The method consists of reacting the methyl esters of the cyclopropenoid fatty acids with silver nitrate in methanol to form ether and ketone derivatives. The derivatives formed from the cyclopropenoid fatty acids are separated from the methyl esters of the normal fatty acids by gas-liquid chromatography on a 15% diethylene glycol succinate column. The method is applicable to oils containing from 0.01% to 100% of cyclopropenoid fatty acids. The derivatives of oils containing lew levels of cyclopropenoids are separated from the normal methyl esters by alumina chromatography prior to gas-liquid chromatography. Studies on the quantitative aspects of the derivative formation, alumina chromatography, and gas-liquid chromatography are reported. Analyses for total cyclopropenoid fatty acid content of cottonseed oil andSterculia foetida oil by the gas-liquid chromatographic and hydrobromic acid titration procedures showed good agreement. Replicate analyses of a sample ofSterculia foetida oil for malvalic and sterculic acid gave coefficients of variation of 6.04% and 1.17%, respectively.     

Quantitative determination of cyclopropenoid fatty acids in cottonseed meal

A rapid analytical procedure for determining the residual cyclopropenoid fatty acids (CPA) in cottonseed meal has been developed. The procedure involves room-temperature extraction of crude CPA-containing lipids with a hexane-water-acetone azeotrope solvent, followed by a benzenemethanol wash. The crude lipids are then converted to methyl esters by methanolysis with sodium methoxide. Extraction with petroleum ether, followed by washing with aqueous acetone, results in a substance which is free from interfering materials. The purified methyl esters are then analyzed for CPA by a spectrophotometric modification of the Halphen reaction.     

The mass spectra of the 4,4-dimethyloxazoline derivatives of the methoxymethyl olefins of malvalic and sterculic acids

A new approach to the gas chromatographymass spectrometry analysis of cyclopropenoid fatty acids is described. The method is based on the “on-site”-modification of the cyclopropenoid ring with AgNO₃-saturated methanol to the methoxymethyl olefin and a subsequent “remote-site”-derivatization of the carboxyl group to its 4,4-dimethyloxazoline. The mass spectra of the isomeric reaction products obtained from malvalic and sterculic acid were found to be useful for locating the original cyclopropenoid ring in the fatty acid chain.     

Methods for the determination of cyclopropenoid fatty acids V. A spectrophotometric method for cottonseed oils based upon the Halphen-test reaction

A spectrophotometric method of analysis for the quantitative estimation of cyclopropenoid fatty acids in cottonseed oil based upon the Halphen-test reaction has been described. Various parameters involved in the reaction have been investigated and two pigment fractions responsible for the characteristic Halphen-test cherry-red color have been isolated. The method is applicable to relatively small amts of sample material. The average deviation from the actual cyclopropenoid acid contents as determined by the stepwise HBr titration method was less than ±0.02% in both the refined and crude oil series. S. Utiliz. Res. Dev. Div., ARS, USDA.     

Methods for the determination of cyclopropenoid fatty acids. II. A stepwise hydrogen bromide titration method for cyclopropenid and epoxy derivatives

A rapid titration method is described for the quantitative determination of both cyclopropenoid and epoxy fatty acid derivatives in mixtures. It was found that epoxy compounds can be titrated selectively with Durbetaki reagent at 3C without interference from cyclopropenoid derivatives. Cyclopropenoid derivatives can be titrated much more rapidly to a much sharper end point a 55C that at room temperature. Thus mixtures can be analyzed by first titrating at 3C to determine the epoxy compounds and then continuing the titration at 55C to determine the cyclopropenoid components. A laboratory of the So. Utiliz. Res. & Dev. Div., ARS, U.S.D.A.     

Methods for the determination of cyclopropenoid fatty acids. VI. A direct infrared absorption method

A simple rapid method for the estimation of the cyclopropenoid content of glycerides and methyl esters is described based upon the measurement of the characteristic infrared absorptivity of cyclopropenoids at 9.9 μ. Autoxidation products do not interfere, and the sample can be recovered. Equations are given for the calculation of the cyclopropenoid content of both glycerides and methyl esters. One of the laboratories of the So. Utiliz. Res. and Dev. Div. ARS, USDA.     

Methods for the determination of cyclopropenoid fatty acids. I. Aqueous hydrochloric acid method

An analytical method is described for the estimation of long-chain cyclopropenoid fatty acid derivatives. It is based upon the quantitative addition of a molecule of hydrogen chloride at the cyclopropene ring when the sample is shaken with concentrated hydrochloric acid. The cyclopropenoid content can be calculated, as sterculic acid, from the increase in chlorine content. Epoxy compounds and hydroperoxides interfere and must be removed by one of the accepted pretreatment methods. A laboratory of the So. Utiliz. Res. & Dev. Div., ARS, U.S.D.A.     

Gas chromatographic analysis of cyclopropenoid acids in cottonseed oils

A gas chromatographic method of analysis for cyclopropenoid acids in cottonseed oil, as the methyl esters, is described. With a glass column packed with a methyl silicone substrate on an inert support, methyl sterculate and methyl malvalate can be chromatographed without decomposition. Although methyl malvalate was not well resolved from methyl linoleate, it could be quantitated accurately at concentrations as low as 0.03% by a peak-height method. Quantitation can be done manually with an internal standard, or with a data system without an internal standard. The method does not require calibration with a cyclopropenoid acid standard, i.e., it is a primary method. Results compare favorably with those obtained by HBr titration. Less than 1 mg of oil is required for an analysis. Retired.     

Extraction of lipids from cottonseed tissue: III. Cyclopropenoid fatty acids from glanded and glandless seed

Principal storage sites of cyclopropenoid fatty acids in glanded and glandless cottonseed tissues were investigated by measuring the content of cyclopropenoid fatty acids in lipids obtained by a cytoplasmic disruptive solvent (hexane-acetone-water) and a non-disruptive solvent (hexane-acetone). The content of cyclopropenoid fatty acids in lipid obtained by either solvent did not differ quantitatively, indicating that cyclopropenoid fatty acids are not stored preferentially in extraspherosomal cytoplasm. Since this observation was also made with glanded tissue, whose glands are thoroughly disrupted by hexane-acetone-water but not by hexane-acetone, the lipoidal material of glands are also not rich in cyclopropenoid fatty acids. These observations indicate that oil-rich spherosomes are the principal sites of cyclopropenoid fatty acids, as well as the reserve oil of cottonseed, and suggest that the greater content of cyclopropenoid fatty acids in lipid prepared by increased periods of solvent-extraction is from release of binding to tissue components, rather than a thorough extraction of somewhat inaccessible (extraspherosomal) areas of tissue. Previous paper in this series is given in Reference 2. ARS, USDA.     

Methods for the determination of cyclopropenoid fatty acids: VIII. The HBr titration method applied to small samples

A method is described for the determination of cyclopropenoid fatty acids in small samples of refined and crude glyceride oils and methyl esters. Approximately 0.5 g of cottonseed oil is titrated with HBr-HOAc by a stepwise procedure at 3 C and 55 C after removal of interfering substances by adsorption on activated alumina. Side reactions occurring to the extent of 15% during the titration were uniform and highly reproducible, permitting application of a correction factor. A procedure is given for preparing methyl esters on a small scale to determine the cyclopropenoid content of highly oxidized oils. The So. Utiliz. Res. Dev. Div., ARS, USDA.     

Chemical inactivation of cyclopropenoid fatty acids in cottonseed meals and their physiological evaluation

Chemical inactivation of cyclopropenoid fatty acids in commercial cottonseed meals was explored with three classes of compounds: anhydrous gases, organic acids and sulfhydryl compounds. Of the reagents screened, sulfur dioxide reduced the cyclopropenoid content by over 90% while free cottonseed fatty acids and thioglycollic acid reduced the cyclopropenoid fatty acid content by over 30%. Large batches of the above three selected meals, as well as a control commercial screw-pressed meal, were then incorporated at 20 wt % levels in the rations of laying hens. A negative control containing 25% soybean meal and a positive control containing a 2% refined cottonseed oil of known CPA content were also employed. During a four-week feeding period, eggs were collected during the third and fourth week and stored at 35 F for periods of 3 and 6 months. Overall egg quality and the fatty acid distribution of the yolk lipids were determined after the 3 and 6 months’ storage periods.     

Analysis of cyclopropenoid and cyclopropanoid acids in fats and oils

The analysis of cyclopropenoid acids may be considered, from a historical standpoint, to have started with the discovery of the Halphen test. Although this test as orginally conceived was utilized as a means of detecting adulteration of premium edible oils with cottonseed oil, it has since been shown to be a characteristic test for cyclopropenoid fatty acids and has been adapted with various modifications as a quantitative colorimetric test for these substances. More recently, spectrophotometric methods particularly in the IR region have been applied to the analysis of these substances. The 9.8 μ band, characteristic of the cyclopropane, and the 9.91 μ band, characteristic of the cyclopropene group, as well as the 11.0 μ band, characteristic of some of the noncyclic degradation derivatives, have been utilized. Gasliquid chromatography (GLC) has been applied to the methyl esters of cyclopropanoid and hydrogenated cyclopropenoid acids. The reactivity of the cyclopropene ring toward hydrohalogens has been the basis of several analytical methods developed for use with cyclopropene acid-containing oils. Both aqueous and nonaqueous solutions of hydrohalogens have been employed. The hydrohalogenation methods are the most precise methods currently available for these analyses but only GLC has the inherent potential of identifying the specific cyclopropenoid or cyclopropenoids involved. So. Utiliz. Res. Dev. Div., ARS, USDA.     

DFT Quantum-Chemical Calculation of Thermodynamic Parameters and DSC Measurement of Thermostability of Novel Benzofuroxan Derivatives Containing Triazidoisobutyl Fragments

New derivatives of benzofuroxan containing triazidoisobutyl fragments, opening the way for the creation of highly effective compositions with an increased value of energy characteristics, were synthesized for the first time. Such compounds are also an excellent platform for further modification and for the preparation of new biologically-active compounds containing tetrazole and triazole fragments. Calculations of heats of formation performed with the DFT (density functional theory) method showed that the studied compounds are high-energetic density ones, the enthalpies of formation of which are comparable to the enthalpies of formation of similar benzofuroxan derivatives and exceeds experimental enthalpy of formation of CL-14 (5,7-diamino-4,6-dinitrobenzofuroxan). The analysis of DSC indicates a sufficiently high thermal stability of the synthesized azidobenzofuroxans, which are acceptable for their use as components in the creation of highly efficient compositions with an increased value of energy characteristics.     

Effect of subacute toxic levels of dietary cyclopropenoid fatty acids upon membrane function and fatty acid composition in the rat

The effect of subacute toxicity levels of dietary cyclopropenoid fatty acids upon several physiological parameters was determined in the rat. Diets containing 2% corn oil, 2%Sterculia foetida oil or 2% hydrogenatedSterculia foetida oil were fed.Sterculia foetida oil (50% cyclopropenoid fatty acids) fed rats exhibited retarded growth, elevated organ to body wt ratios, increased saturation of tissue lipid, and abnormal histopathology when compared to corn oil and hydrogenatedSterculia foetida oil fed rats. Growth was retarded 50%, liver/body wt doubled, and the percentage of saturated fatty acids in adipose tissue increased 2.5-fold forSterculia foetida oil vs. corn oil comparisons. Three membrane systems were examined in corn oil andSterculia foetida oil fed rats. Erythrocyte hemolysis rate in 0.3 M glycerol was increased by 30%; induction of mitochondrial swelling by reduced glutathione was inhibited completely and microsomal codeine demethylase activity was depressed nearly 50% inSterculia foetida oil fed rats. The ability of cyclopropenoid fatty acids to inhibit fatty acyl desaturase and influence tissue and membrane lipid composition is discussed. Most of the detrimental effects observed in cyclopropenoid fatty acids fed rats may be associated with alteration of normal lipid metabolism and membrane function.     

Assay of cyclopropenoid lipids by nuclear magnetic resonance

Nuclear magnetic resonance (NMR) method for the quantitative analysis of cyclopropenoid fatty acids (CPFA) in lipids is described. Good accuracy is obtained at CPFA concentrations of 1% to 100%. At a CPFA concentration of 10%, NMR is accurate to 0.5%. The position of absorption of the two ring methylene hydrogens is solvent dependent.     

水性醇酸树脂及其聚氨酯改性的研究

采用一步法合成了端羟基醇酸树脂,给出了其聚氨酯改性的合成工艺,探讨了醇酸树脂的数均分子量、油度对改性后漆膜性能的影响;从漆膜的铅笔硬度、附着力、耐水性、黏度等方面进一步考察了DMPA的用量、-NCO/-OH比值、扩链方式及其它因素的影响,并得出了最佳的原料配比。     

Applying high resolution SyXRD analysis on sulfate attacked concrete field samples

High resolution synchrotron X-ray diffraction (SyXRD) was applied for a microstructural profile analysis of concrete deterioration after sulfate attack. The cement matrices consist of ordinary Portland cement and different amounts of supplementary cementitious materials, such as fly ash, natural pozzolana and granulated blast furnace slag. The changes of the phase composition were determined along the direction of sulfate ingress. This approach allows the identification of reaction fronts and zones of different phase compositions and conclusions about the mechanisms of sulfate attack. Two reaction fronts were localized in the initial 4 mm from the sample surface. The mechanism of deterioration caused by the exposition in the sulfate-bearing soil is discussed. SyXRD is shown to be a reliable method for investigation of cementitious materials with aggregates embedded in natural environments.     

Compositions and Microstructures of the Primary Ceramic Materials in the Paleolithic Age Through XRD, SEM, and TEM Analyses

The mineral compositions and microstructures of Paleolithic materials were first investigated by X-ray diffraction analysis, scanning electron microscopy, and transmission electron microscopy in order to understand the primary ceramic material in human history. Shale and chalcedony artifacts excavated from upper Paleolithic sites were analyzed. As a result, from among various candidates with nonuniform mineral compositions, only limited materials containing polycrystals with approximately more than 95%α-quartz content were selected as tool materials. Moreover, every Paleolithic material invariably exhibited densely packed and homogeneous micrograins approximately 0.1–0.5 μm in size and an equigranular structure with few porosities at the grain boundaries.     

Chemosetting resins containing fillers. I. Unsaturated polyester resin compositions containing modified smectites

Smectic clays with quaternary ammonium salts (QAS) were subjected to hydrophobization, whereupon we applied the products in attempts to modify various polymers. The clays were of natural origin and contained a large proportion of montmorillonite and an original method of modification was applied. A significant improvement of the stability of unsaturated polyester (UP) resins, modified with clays modified with QAS, was observed with essentially no change in the reactivity of resins. The compositions of polyester resins containing 2 wt % of modified smectites had excellent thixotropy. The presence of modified bentonites in a cured commercial UP resin (2–4 wt %) improved its tensile strength (by 21–62%), Brinell hardness (23–70%), and unnotched impact strength (23–100%), depending on the type of bentonite used. The compositions of UP resins with modified clays had certain properties typical for nanocomposites: improved stiffness, strength, transparency, and fine‐lamellar morphology of the fracture as found by electron scanning microscopy. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 793–801, 2005     

Tuning the mechanical performance and adhesion of polyurethane UV cured coatings by composition of acrylic reactive diluents

An approach to modify the properties of UV curable polyurethane coatings by altering the amount and functionality of acrylic reactive diluents, in order to optimize the coating performance, is demonstrated. Based on the rheology analysis, a model of the rheological behavior of the UV curable materials depending on the amount and type of a reactive diluent in the composition is demonstrated in this study. The relationships between the rheological behavior, the mechanical properties and adhesion of the coatings prepared from polyurethane UV curable compositions containing different amounts and functionalities of acrylic reactive diluents, have been investigated and discussed in this study. Based on the results of the study, the desired properties of UV cured coatings can be modeled and controlled without changing the nature of a particularly selected oligomer, thus maintaining the advantages of its chemical structure in a coating composition.