Preparation of stearidonic acid‐enriched triacylglycerols from Echium plantagineum seed oil

HPLC analysis of Echium plantagineum seed oil shows a complex triacylglycerol (TAG) profile. TAG species were separated on an analytical scale by HPLC and their fatty acid (FA) composition is reported. GLC analyses showed that some TAG fractions reached a stearidonic acid (SDA, 18:4n‐3) percentage significantly higher than that in the original oil. TAG separation on a bigger scale was also essayed, by means of a gravimetric normal‐phase chromatographic column, using silver ion‐silica gel as stationary phase. Gradient elution with solvents of increasing polarity was applied, allowing the separation of valuable TAG species containing γ‐linolenic acid (GLA, 18:3n‐6), α‐linolenic acid (ALA, 18:3n‐3) and SDA as the main constituents (more than 85% of the total FA). An enzymatic hydrolysis reaction showed the distribution of FA in the isolated species of TAG. SDA was the major FA in the sn‐2 position (more than 50% of total FA), followed by ALA (19%) and GLA (18.5%).     

Separation of crude palm oil components by semipreparative supercritical fluid chromatography

Successful separation of triglycerides, diglycerides, free fatty acids, carotenes, tocopherol, and tocotrienols from crude palm oil has been achieved by supercritical fluid chromatography (SFC) with a combination of a C18 and a silica gel column. The separation was carried out by the programmed extraction elution method. Free fatty acids were separated into five components by gas-liquid chromatography; tocopherol and tocotrienols were also separated into four components by SFC analysis, and the pure fractionated carotenes were obtained by preparative SFC. Thus, by using supercritical fluid chromatography, crude palm oil components can be separated and fractionated, based on differences in their functional groups.     

A new concept for determining triglyceride composition of fats and oils by liquid chromatography

The matrix concept was used to characterize the chromatographic rules in the elution of molecular species of triglyceride. To prove the hypothesis experimentally, cacao butter, palm oil, linseed oil, olive oil, rapeseed oil and triglyceride of “Ogonori” (Gracilaria verrucosa) were examined. A matrix model was suggested to help determine the individual molecular species of naturally occurring triglycerides.     

Analysis of triglyceride species by high-performance liquid chromatography via a flame lonization detector

The analysis of triglyceride species by high performance liquid chromatography (HPLC) with a flame ionization detector (FID) and reversed-phase chromatography using chemically bonded octadecyl silane (ODS) Zorbax columns and gradient or isocratic solvent elution with methylene chloride/acetonitrile is described. Triglycerides containing acyl groups of critical pairs,trans and positional isomers, as well as mixtures of even and odd chain lengths are separated. Identification of triglycerides is made on the basis of retention times compared with equivalent and theoretical carbon numbers, and comparison with chromatograms of reference triglyceride mixtures. The methodology is demonstrated by fractionizing the triglycerides of olive oil under different chromatographic conditions using single and coupled conventional 250×4.6 mm columns and a short 80×6.2 mm column for fast separations.     

Oil fingerprint identification technology using a simplified set of biomarkers selected based on principal component difference

Gas chromatography–mass spectrometry (GC–MS), which can separate and quantify thousands of individual petroleum biomarker compounds, is generally acknowledged as the most powerful technique for oil fingerprinting nowadays. Traditional oil fingerprint studies employ the whole suite of biomarkers measured in chromatographic analysis, which is prone to introducing ambiguous variables in the whole set and being time and labour intensive. To extract the most representative and meaningful indicators for the oil fingerprinting and identification, this paper proposes a method based on principal component difference to select a simplified set of biomarkers, providing the possibility of faster elution and analysis procedures. For the purpose of further verifying the reliability and accuracy of our method, identification simulation experiments including principal component analysis (PCA) spatial clustering, hierarchical clustering, and generalized regression neural network are carried out with the whole set and the simplified set of biomarkers, respectively. All the results and analyses demonstrate that the simplified set of biomarkers selected by our proposed method can achieve almost the same or even better identification results than those of the whole set of biomarkers.     

Liquid Chromatographic fractionation of oil-sand and crude oil asphaltenes

Asphaltenes extracted from Alberta oil sands (Athabasca, Cold Lake, and Peace River) and crude oils (Taber South and Fenn-Big Valley) were fractionated by sequential elution solvent chromatography (SESC) involving 10 organic solvents on a silica column. Athabasca asphaltenes and SESC fractions were further studied by elemental analysis, i.r., u.v., and n.m.r. spectroscopy. Incomplete extraction of maltenes from the oil-sand bitumens increased the yields of the first two SESC fractions, the saturates and aromatics, of oil-sand asphaltenes relative to the crude oil asphaltenes. About 55 wt% of the asphaltenes elute in fractions 3–5. Two distinct molecular types are present in the asphaltenes; namely, lower functionality species with lower heteroatom content and the higher functionality species with higher heteroatom content. Compounds eluting in fractions 3–10 are predominantly polynuclear aromatics with alkyl substituants and probably bridged by cycloalkanes. The extent of bridging as well as the location, number and type of heteroatoms determines the fraction in which each compound appears. Complexity of compounds eluting increases with time: earlier fractions are composed of smaller-size polynuclear aromatic centers and contain heteroatoms in predominantly ring locations, whereas later fractions contain a larger proportion of complex species and more functional heteroatom groups.     

Identification of the less common isologous short-chain triacylglycerols in the most volatile 2.5% molecular distillate of butter oil

The isologous short-chain triacylglycerols of the most volatile 2.5% distillate of butter oil were resolved by reversed-phase high-performance liquid chromatography (HPLC) with mass spectrometry. The molecular species were identified by means of the [MH]⁺ and the [MH-RCOOH]⁺ ions in positive chemical ionization mode. A set of empirically determined incremental elution factors was found that could be used to calculate the accurate elution order of natural butterfat triacylglycerols when analyzed by reversed-phase HPLC. The triacylglycerols were also resolved by temperature-programmed gas-liquid chromatography on capillary columns coated with polar liquid phases. The high polarity of the columns provided separation of triacylglycerols on the basis of the degree of unsaturation, as well as on the nature of the shortest acyl chain, with the isologous species having the shortest chainlength eluting last. Both saturated and unsaturated triacylglycerols containing normal and branched-chain odd-carbon fatty acids in combination with short-chain acids were identified, and over 150 molecular species were quantitated.     

Spectroscopic investigations of solvent-refined coal fractions

The chemical characteristics of Amax solvent-refined coal are investigated on a molecular size and component basis. Gel permeation chromatography (g.p.c.) is used to characterize the tetrahydrofuran-soluble portion of the SRC and to obtain the molecular size distributions, and is also used as a preanalysis step, in which fractions are obtained according to elution time. The THF-soluble portion of the SRC has elution times comparable to asphaltene plus oil. The resultant g.p.c. eluent is divided into six fractions, three of which have molecular sizes and elution times comparable to asphaltene alone, two to oil, and one to asphaltene plus oil. These observations are confirmed by chemical ionization and electron impact mass spectrometry. Various analytical techniques are used to establish further the composition of the fractions, including: infrared spectrometry, elemental analysis, flourescence excitation and emission spectrometry, high-pressure liquid chromatography and gas chromatography.     

Triacylglyceride composition of cottonseed oil by HPLC and GC

The triacylglyceride components of cottonseed oil were isolated and positively identified by a combination of high performance liquid chromatography (HPLC) and gas chromatography (GC). Both reversed-phase HPLC and capillary GC were capable of separating the oil into triacylglyceride peaks. These peaks were isolated by HPLC and their component acyl groups were converted to fatty acid methyl ester derivatives. The acyl constituents for each triacylglyceride were determined by GC analysis, thus positively identifying the triacylglyceride associated with each HPLC peak. The triacylglyceride elution order agreed with predictive methods. HPLC and capillary GC peaks were correlated by peak area, thus identifying the GC peaks. The corresponding GC elution order of triacylglycerides also agreed with predictive methods.     

Experimental Conditions for HPLC Analysis of Ethoxylated Alkyl Phenol Surfactants in Microemulsion Systems. Part II. Gradient Mode for Extended EON Range as Found in the Analysis of Oligomer Fractionation

Abstract

The different oligomers of ethoxylated nonylphenols present in commercial surfactants can be separated by HPLC. While low ethylene oxide number (EON) species may be separated by isocratic HPLC on silica, intermediate EONs require gradient elution HPLC. The separation of higher oligomers can be carried out with an intermediate polarity column of the NH₂ type and a solvent gradient. The suggested experimental conditions allow a satisfactory single run separation of a complex mixture with EONs ranging from 1 to 25 by using a linear gradient from 100% less polar solvent (n-heptane—chloroform—methanol 90/5/5) to its mixture with up to 20% of a more polar solvent made of chloroform—methanol (50/50). This method is used to analyze the EON distribution resulting from the mixing of different commercial surfactants. When two surfactants with very different EON distributions are mixed to produce a formulation scan, the occurrence of three-phase behavior at the optimum formulation of the surfactant—oil—water system is found to correlate with the absence of a gap in the overall EON distribution. Both the fractionation of low EON species into the oil phase and the fractionation of high EON oligomers into the water phase result in a depletion of the microemulsion phase.     

High-temperature gas chromatography for the detection of trierucoylglycerol in the seed oil of transgenic rapeseed (Brassica napus L.)

A method for the determination of the triacylglycerol (TAG) composition of the seed oil of rapeseed (Brassica napus L.) by high-temperature gas chromatography (HT-GC) has been developed. For oil quality breeding in rapeseed such a method gains increasing importance since by means of molecular gene transfer novel TAG species, e.g. like trierucoylglycerol are developed, for the detection of which, however, no adequate efficient method is available. The HT-GC method is quicker in comparison to the conventionally used HPLC method and the analysis can be performed with minute amounts of oil, as they are available by means of oil extraction from single cotyledons of microspore-derived embryos and from ‘half-seeds’ of rapeseed. Following the triacylglycerol analysis, enough oil remains to allow the determination of the fatty acid composition of the same sample.     

Ultrasonically assisted solid-phase extraction and GC analysis of filbertone in hazelnut oil

Ultrasound was used to assist solid-phase extraction (SPE) of filbertone (E-5-methylhept-2-en-4-one) from hazelnut oil. Interferences from TG were reduced for effective separation and detection during chromatographic analysis. The enantiomeric distribution of filbertone was determined. Different sorbent materials, sample volumes, and eluents were tested, and the effect on filbertone recovery by ultrasound during the elution step was evaluated. Experimentation performed on a 2-mL volume of oil diluted with a 2-mL volume of n-hexane, using a silica modified with either a cyano or phenyl group during the extraction, and ultrasound-assisted elution with a 1-mL volume of chloroform allowed filbertone recoveries of up to 94.4% (relative SD 6.5%) vs. 11% obtained when ultrasound was not applied. This improvement is most likely due to a mechanism of cavitation. Ultrasonically assisted SPE is proposed as an accesible and simple alternative to multidimensional chromatographic techniques to accomplish the reliable determination of the enantiomeric excess of chiral compounds in complex matrices, such as hazelnut oil, since experimental conditions that can bring about racemization are not required.     

Simple and Efficient Profiling of Phospholipids in Phospholipase D-modified Soy Lecithin by HPLC with Charged Aerosol Detection

Dietary phosphatidylinositol (PI) can be synthesized via phospholipase D (PLD)-catalyzed transphosphatidylation of phosphatidylcholine (PC), abundant in soy lecithin, with myo-inositol. However, a generated mixture of phospholipid (PL) classes poses a challenge for analysis. Our current work on Streptomyces PLD engineering requires a robust analytical method for profiling of PI and related PLs derived from the transphosphatidylation reactions. Therefore, we optimized an HPLC-based method with charged aerosol detector (CAD) for PL quantification. PLs were separated on a normal phase silica column by a gradient elution system using two solvents containing chloroform/methanol/1 M formic acid–triethylamine buffer in different ratios. Retention times of the PL standards and LC–MS under identical conditions were used to identity PL classes. PL standards gave linear response in 100- and 10-fold (lyso-PI) concentration range. The method provided a simple, sensitive, repeatable, and precise analysis of PI, PC, phosphatidylethanolamine, phosphatidic acid, and lyso forms of PC and PI. Compared to the similar existing method, introduction of CAD provided a three- to fivefold decrease at the lower end and a two- to fivefold increase at the upper end of the dynamic range. High precision, high sensitivity, and low limits of detection and quantification further underline the benefits of CAD in PL analysis.     

HPLC of triglycerides with gradient elution and mass detection

A gradient elution reversed phase HPLC system with a mass detector was investigated for the separation of triglycerides. A gradient based on a ternary eluent mixture is suggested. The detector was investigated in terms of linearity, reproducibility and relative response. The separation of soybean oil and some other natural triglyceride mixtures is demonstrated.     

Modelling of oil shale pyrolysis in a fluid-bed retort

Pyrolysis of large oil shale particles in an isothermal fluid bed retort is theoretically studied in this paper. The governing equations describing diffusion and chemical reaction inside shale particles are solved analytically by using a finite Sturm—Liouville integral transform technique. The analysis gives not only the final distribution of products but also the dynamic response of these species from the onset of operation. Based on the information of the final product distribution (yield) and the dynamic response, the model solutions give guidance in choosing a proper temperature to operate the fluid bed retort for a given size of oil shale particle.     

A new method for determining molecular weight distributions of copolymers

Measurement of the molecular weight distributions of copolymers by size exclusion chromatography (SEC) presents problems because the elution volume of any species may depend on its composition as well as its molecular weight. Also, the response of the usual concentration detectors may also be influenced by the copolymer composition as well as its concentration. These problems arise when the copolymer composition may vary with molecular size. Conventional SEC techniques are suitable for copolymers with invariant compositions. This article describes and illustrates a method for measuring molecular weight distributions of copolymers. In many cases, the variation of copolymer composition with molecular weight can also be determined. The technique uses three detectors: (a) an evaporative detector (ED) to measure the concentration, Δc, of the eluting species; (b) a differential refractive index detector (DRI) to measure the refractive index difference, Δn, between the solution and solvent at any given elution volume; and (c) a low-angle laser light scattering (LALLS) detector that measures the corresponding molecular weight of the eluting solutes. This latter measurement is possible because the appropriate values of Δn/Δc are available from the outputs of the other two detectors. For LALLS measurements of molecular weight all the species in the detector cell at any instant must have the same composition or, at least not have Δn/Δc that varies with composition. The method is illustrated with data from ethylene-propylene and ethylene-propylene-diene copolymers.     

Characterization of α- and γ-linolenic acid oils by reversed-phase high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry

Triacylglycerols of oils rich in α- and/or γ-linolenic acids were analyzed by reversed-phase high-performance liquid chromatography (HPLC) coupled with atmospheric pressure chemical ionization mass spectrometry [(APCI)MS]. The (APCI)MS spectra of most triacylglycerols exhibited [M + H]⁺ and [M - RCOO]⁺ ions, which defined the molecular weight and the molecular association of fatty acyl residues, respectively. Reversed-phase HPLC resulted in, at least, partial separation of triacylglycerols containing α- and/or γ-linolenic acid moieties. Molecules containing α-linolenic acid residues exhibited a relatively weaker retention by the stationary phase than the corresponding molecules containing γ-linolenic acid residues. Good separation of triacylglycerols of cloudberry seed oil, evening primrose oil, borage oil, and black-currant seed oil was achieved. The molecular species identification of separated components was based on the (APCI)MS data as well as on the elution properties of triacylglycerols on reversed-phase HPLC. This study demonstrated the efficiency of HPLC-(APCI)MS in determining the molecular species compositions of triacylglycerols in complex natural mixtures. Good quality mass spectra could be extracted even from minor chromatographic peaks representing 0.2% or less of the total triacylglycerols.     

Pressure Response through Valve for Continuous Oil-Water Separation Based on a Flexible Superhydrophobic/Superoleophilic Thermoplastic Vulcanizate Film

Highly efficient oil-water separation shows urgent demand in industrial applications, especially in oil-spill accidents and organic solvent separation. Herein, a novel method is proposed for continuous oil-water separation by a pressure response through valve, which is loaded in a flexible convolute superhydrophobic/superoleophilic film based on low-density polyethylene (LDPE)/ethylene-propylene-diene terpolymer (EPDM) thermoplastic vulcanizate (TPV). The superhydrophobic/superoleophilic LDPE/EPDM TPV film (with contact angles of oil and water are 0° and 161.9°± 2.2°) is prepared only via a molding process where sandpaper is used as the template. The superhydrophobic/superoleophilic property of the TPV film shows robust performance in the activity endurance test. More importantly, the flexible LDPE/EPDM TPV film can be easily rolled up and loaded in through valve, which is the pressure response channel in oil-water separation. The typical separation pressure of oil and water is 3.01 and 6.17 kPa, which means the oil can be completely separated from the oil-water mixture under proper pressure in the pressure response through valve.     

Imprinted polymer-based extraction for speciation analysis of inorganic tin in food and water samples

In this study, an ion imprinted polymer (IIP), tin (IV)–4-(2-pyridylazo) resorcinol (PAR) complex (Sn(IV)–PAR–IIP) has been synthesized for speciation and selective solid-phase extraction (SPE) of tin species from food and water samples. For this purpose, copolymerization of Sn(IV)–4-(2-pyridylazo) resorcinol (PAR) complex was performed using methacrylic acid (MAA), ethylene glycol dimethacrylate (EGDMA), and 2,2′-Azobisisobutyronitrile (AIBN) as functional monomer, cross-linking agent, and initiator, respectively. The polymer particles were characterized by FT-IR, and thermogravimetric (TG) analyses. The effects of different variables such as solution pH, mass of the polymer, extraction and elution time, and type and volume of the eluent for elution of tin were evaluated by Box–Behnken design and response surface methodology. The significance of independent variables and their interactions were tested by the analysis of variance (ANOVA) with 95% confidence limits. The optimal conditions at extraction step were 8, 70 mg, and 25 min for solution pH, amount of polymer, and extraction time, respectively. Also, the optimal values for the elution step were 6.5 mL of HCl (4 M) as the eluent volume and type and elution time of 120 min. The detection limit of the proposed method was found to be 1.3 μg L^?1 and a linear dynamic range (LDR) in the range of 5–200 μg L^?1 was obtained. The influence of various cationic interferences on recovery percentage of Sn(IV) was studied. The method was applied to recovery and determination of tin species in different real samples.     

Alkali isomerization—Gas chromatography with the microreactor apparatus

A simple and rapid method of simultaneously conjugating polyunsaturation and forming methyl esters from triglyceride oils, other esters and fatty acids has been developed by using the microreactor apparatus (MRA). These reactions occur while a mixture of tetramethylammonium hydroxide and sample of fat is being injected into a gas chromatograph from the MRA reaction chamber. The speed of this microanalysis is limited only by peak elution and peak integration times. Analyses of soybean oil and six partially hydrogenated fats have been compared with those previously obtained by the alkali isomerization spectrometric method. The amount of conjugation that occurs during the reaction is a measure of the linoleic acid in the oil. This procedure should prove useful for rapid microscale analysis of conjugatable dienes in a variety of samples, including edible fat products. Presented at the Fall ISF-AOCS Meeting, Chicago, September 1970. No. Market. Nutr. Res. Div., ARS, USDA.