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1.
Summary The fatty acid composition of a number of vegetable oils and of two synthetic mixtures of methyl esters are compared by gas-liquid
chromatography and by standard methods. The calculated iodine values from G.L.P.C. results are in good agreement with measured
iodine values and are indicative of the reliability of the G.L.P.C. values. Standard methods gave lower values for linoleic
acid and higher values for linolenic acid than did G.L.P.C. This deviation was particularly evident in oils with a high proportion
of linolenic acid,e.g., linseed oil. The results of G.L.P.C. are considered to be accurate to within one unit percentage. Thermal stability of the
polyester polymers can be improved by using 1,4-butanediol or ethylene glycol as the polyols instead of diethylene glycol.
Issued as N.R.C. No. 5373.
Presented at 32nd annual fall meeting, American Oil Chemists' Society, October 20–22, 1958, Chicago, Ill.
National Research Council of Canada Postdoctorate Fellow, 1957 相似文献
2.
J. L. Iverson J. Eisner D. Firestone 《Journal of the American Oil Chemists' Society》1965,42(12):1063-1068
The detection of trace fatty acids (<0.1%) in a fat or oil by gas-liquid chromatography is possible when the methyl esters
are fractionated with urea to provide a number of less complex fractions. Identification and estimation of trace fatty acids
is simplified by quantitative removal of other fatty acids having similar gas chromatographic retention times. A detailed
knowledge of the order in which inclusion compounds are formed was obtained by fractionating a complex mixture of marine and
vegetable fatty acids. In addition, lanolin was fractionated to determine the preferential order in which saturated, branched
chain (iso-, anteiso-) and hydroxy acids form inclusion compounds. Using urea fractionation and gas chromatography, 52 trace fatty acids were tentatively
identified in butter, 30 in lard, and 26 in walnut oil.
Presented at the AOCS Meeting in New Orleans, 1964. 相似文献
3.
S. F. Herb Paul Magidman R. W. Riemenschneider 《Journal of the American Oil Chemists' Society》1960,37(3):127-129
- Known mixtures of pure fatty acid methyl esters and a number of fats and oils as their methyl esters have been analyzed by conventional GLC with thermal conductivity detectors.
- Percentage of fatty acid distribution determined by GLC agreed well with known percentages in model mixtures and with analysis by the spectrophotometric method for fats and oils.
- Determination of very small amounts of arachidonic and pentacnoic acids in lard by GLC was not successful.
4.
5.
W. De Greyt M. Kellens A. Huyghebaerts 《European Journal of Lipid Science and Technology》1996,98(4):141-144
Twenty-seven commercial bakery products marketed in Belgium were analyzed by gas-liquid chromatography for their trans (TFA) and polyunsaturated fatty acid (PUFA) content. The mean PUFA level for the bakery fats in our study was 8.85% (S.D. = 9.90%) and the TFA content ranged from 0.0–18.81% (mean = 5.99%; S.D. = 5.02%). The unfavourable fatty acid profile of most of the analyzed bakery fats can be explained by the frequent use of animal fat and partially hydrogenated oils. The average daily intake of TFA from bakery products by the Belgian population was calculated at 0.43g/person/day. As it is expected that their consumption will increase in the future, lower TFA levels in bakery fats are necessary to avoid that these products become a more important dietary source of TFA. 相似文献
6.
Carter Litchfield Raymond Reiser A. F. Isbell 《Journal of the American Oil Chemists' Society》1963,40(7):302-309
The geometric isomers of many unsaturated fatty acid methyl esters can be separated using high-resolution gas-liquid chromatography
on polyester or Apiezon columns. Separations reported for the geometric isomers of monounsaturated, ricinoleic, linoleic,
conjugated, and epoxy fatty acids are reviewed here. New data is presented on the resolution of linolenate geometric isomers
on both polyester and Apiezon columns. The separation of methyl oleate and methyl elaidate on a polyester column has also
been accomplished. Techniques for preparing and using the high-resolution columns necessary for these separations are reviewed.
Presented at the AOCS meeting in New Orleans, La., 1962.
Supported in part by a grant from the National Institutes of Health (A-6011). 相似文献
7.
Tetsuo Sato Sumio Kawano Mutsuo Iwamoto 《Journal of the American Oil Chemists' Society》1991,68(11):827-833
A near infrared (NIR) spectral pattern of oil contains information about fatty acid composition, because NIR absorption bands
around 1600–1800 nm and 2100–2200 nm are due to the straight carbon chain andcis double bonds, respectively. This study was undertaken to build a foundation for the rapid determination of the fatty acid
composition in oil by an NIR method. First, NIR spectra of pure triglycerides were measured and characterized. Fatty acid
compositions could be estimated roughly by comparing the spectra of fats and oils (butter fat, pig milk fat, soybean oil and
palm oil) with those of pure triglycerides. Secondly, the NIR spectra of these fats and oils were reconstructed by summation
of the triglyceride spectra, which are multiplied by factors corresponding to the fatty acid composition of the sample determined
by gas chromatography. The calculated spectra agree with the originals, especially for that of soybean oil. However, in order
to reconstruct spectra precisely, it may be necessary to reevaluate the loading weight of each triglyceride, which was equal
in this study.
Part of this study was presented at the 3rd International Conference on Near Infrared Spectroscopy on June 28, 1990, Brussels,
Belgium. 相似文献
8.
B. Sreenivasan 《Journal of the American Oil Chemists' Society》1968,45(4):259-265
Nineteen different samples of oils and fats have been examined for their component acids and composition by gas-liquid chromatography.
Under programmed-temperature operations, the temperatures at which different components start to elute bear a straight-line
relationship with their respective carbon numbers. Chromatograms, under programmed-temperature conditions, of methyl esters
from such oils as coconut, groundnut, mustard, etc., are used for identifying the components of an unknown oil by comparing
its chromatogram taken under nearly identical conditions. For confirmatory identifications, such plots as logarithm of retention
times versus carbon numbers for saturated acids (14:0 to 24:0), monoenoic acids (14:1 to 24:1), and dienoic acids (18:2 to
24:2), under isothermal conditions, have also been used. Some new fatty acids, noted for the first time in traditional oils,
are 15:0 in cottonseed oil, 20:1 in sesame oil, 22:0 in soybean oil, and 24:2 in mustard oil. Odd-carbon chain acids from
11∶0 to 23:0 have been observed in such vegetable oils as peanut germ, rice bran, andMesua ferrea. Fatty acid composition by GLC for new samples like peanut lecithin, peanut germ oil,Myristica attenuata, Myristica kanarica, Myristica magnifica, Mesua ferrea, Vateria indica, Schleichera trijuga, and shark-liver stearine are presented. Industrial utilization of these new oils and fats is discussed. 相似文献
9.
The generally accepted approach to the analysis of fatty acid methyl esters (FAME) by gas liquid chromatography (GLC) is to
analyze a standard mixture of known composition and to determine empirical correction factors for individual FAME. These correction
factors, which are a composite of the theoretical flame ionization detector (FID) relative response factors and an empirical
factor to correct for any system errors that may be present, then are used to correct the raw peak areas of the individual
FAME of the sample undergoing analysis. It is proposed that this approach is fundamentally unsound as a means of generating
consistently accurate results. Rather, it has been proven that theoretically calculated FID relative response factors are
valid, both for the saturated and unsaturated FAME commonly encountered in edible oils, and that these should be used as the
only response factors for the correction of raw peak areas. Thus, the proper approach to the generation of highly accurate
results is to optimize both equipment and operator technique so that a correct answer is obtained for a primary standard when
these theoretical factors are used, rather than to introduce an empirical correction factor other than the theoretical response
factor to take account of faulty practice. Eight facets of equipment operation or operator technique have been identified
which must be addressed to optimize accuracy.
Presented at the 77th Annual AOCS Meeting in May 1986 in Honolulu, Hawaii. 相似文献
10.
E. R. Sherwin 《Journal of the American Oil Chemists' Society》1972,49(8):468-472
Types of antioxidants currently available for food fats and oils are listed, and theoretical and practical aspects of selecting
the proper ones for various food uses are reviewed. Consideration is given to relative potencies, modes of application, regulations
governing use, and some of the more prominent problems encountered in their commercial applications. A brief look is taken
into future needs and possible developments with fat and oil antioxidants.
One of seven papers presented in the symposium “Fats and Oils in Food Industry,” AOCS Meeting, Atlantic City, October 1971. 相似文献
11.
12.
M. Buchgraber F. Ulberth E. Anklam 《Journal of the American Oil Chemists' Society》2000,77(6):653-657
The effect of using different gas-liquid chromatography (GLC) hardware to quantify low concentrations of fatty acids was studies. A fused-silica capillary column was operated in two different chromatographs (A and B) that were interfaced to three different chromatographic data systems to process the flame-ionization detector signals (systems A, B1, and B2). A test routine was developed that allowed the proper selection of peak processing parameters for the automatic recognition and integration of fatty acids occurring at trace levels. However, agreement of analytical results between the three analytical systems was not satisfactory; components at concentrations <0.10 g/100 g could not be quantified with high reliability, although the same capillary column and identical sample solutions were used (quasi-repeatability conditions). Even for major fatty acids, deviations up to 1.0 g/100 g were noted, which could only be attributed to the use of different GLC hardware. Attention should be paid to these technical restrictions when formulating product specifications based on fatty acid profile parameters. 相似文献
13.
A method of combustion/ion chromatography (C/IC), initially developed for the determination of sulfur, has been extended to
determination of total nitrogen in fats and oils. It is shown that nitrogen gas dissolved in the sample interferes with the
determination, and that it is necessary to degas the sample before analysis. Moreover, there is a procedural blank for the
nitrogen in the cylinder oxygen employed. Despite these drawbacks, the method has advantages over conventional methods, in
that (i) measurements can be carried out with standard laboratory equipment, and (ii) nitrogen and sulfur, and possibly halogens
and selenium, can be determined simultaneously. 相似文献
14.
15.
Edmund D. George 《Journal of the American Oil Chemists' Society》1994,71(7):789-791
A high-performance liquid chromatography (HPLC) procedure without derivatization was developed for quantitating fatty acid components of various soap-related fats and oils, as well as for the direct quantitation of fatty acids from soap. The fatty acids are detected by refractive index after isocratic reverse-phase chromatography. The method has been developed with radial compression and stainless-steel column technology. The triglycerides are saponified and acid-hydrolyzed into fatty acids, and they are dissolved in a solvent and injected. The soaps are dissolved in methanol and injected into the HPLC, where they are acid-hydrolyzed directly on the column by an acid-modified mobile phase. The total run time after injection is approximately 20 min, with quantitation performed on an NEC Powermate® computer driven by PE/Nelson Analytical Software. The typical carbon chains analyzed are from C6 to C20. 相似文献
16.
A method is described to determine cyclic fatty acids in cyclic monomers by gas-liquid chromatography (GLC), which separates
saturated straight-chain esters from cyclic esters. The content of cyclic esters can be determined by integration of the area
on the chromatograph under the cyclic peaks. GLC was applied to cyclic monomers made from linseed oil and from linolenic acid.
Samples of both hydrogenated and nonhydrogenated cyclic monomers were analyzed; however, more reliable results were obtained
on the hydrogenated samples. The results show a standard deviation of 0.25 for linseed oil and 0.36 for linolenic acid.
Accuracy of the analysis was established by comparing data with that obtained by crystallization. The GLC method is approximately
three times faster.
Presented at the AOCS meeting, New Orleans, La., 1962.
A laboratory of the No. Utiliz. Res. & Dev. Div., ARS, U.S.D.A. 相似文献
17.
H. H. Hofstetter N. Sen R. T. Holman 《Journal of the American Oil Chemists' Society》1965,42(6):537-540
The equivalent chain length (ECL) has been determined on 79 methyl esters of unsaturated fatty acids and on 7 ethyl esters
by gas chromatography. Ethylene glycol succinate (EGS), diethylene glycol succinate, β-cyclodextrin acetate and Apiezon L
were chosen as the liquid phases to be used. For methyl esters of mono- and polyenoic acids, the differences between ECL on
EGS and ECL on Apiezon L approximate 0.84 per double bond. For positional isomers, the ECL on both EGS and Apiezon L are usually
greater for the isomer having the longer proximal end of the molecule (smallest ω value). In these terms a triple bond is
approximately equal to three double bonds. Esters of nonconjugated dienoic and trienoic acids of the same chain length are
not separable on Apiezon L if their proximal structures are the same. This also applies to tetraenoic and pentaenoic acids
of the same chain length and the same proximal structure. Conjugation of double bonds, either with the ester carbonyl group
or with themselves, yields ECL values on Apiezon L greater than the number of carbon atoms in the acid. Monounsaturated and
nonconjugated polyunsaturated esters have ECL values on Apiezon L lower than the number of carbon atoms of the acid. The ECL
values of ethyl esters of 18 and 20 carbon acids are greater than the corresponding methyl esters on Apiezon L.
Presented at the Chicago meeting of the American Oil Chemists’ Society, Oct. 13, 1964. 相似文献
18.
G. S. M. J. E. Duchateau H. J. van Oosten M. A. Vasconcellos 《Journal of the American Oil Chemists' Society》1996,73(3):275-282
For quantitation ofcis- andtrans-fatty acid isomers, infrared (IR) spectroscopy, gas-liquid chromatography (GLC) on highly polar stationary phases or the combination (GLC-IR) may be used. IR offers the advantage of simplicity and speed, but the lower determination limit of 5% and the lack of detailed information limit its use. Detailed fatty acid information, required for, e.g., food-labeling purposes, can only be obtained with GLC methods. Most of the GLC methods are optimized for partially hydrogenated samples. AOCS Official Method Ce 1c-89 prescribes a single, highly polar stationary phase, SP2340, but underestimates the amount oftrans isomers due to 18∶1 positional isomer overlap. The combined GLC-IR method may circumvent this problem but at the cost of time, effort, and precision.Trans isomers in refined (deodorized or stripped) oils are different in type and levels from isomers in partially hydrogenated oils; theirtrans isomers are mono-trans trienoic and dienoic isomers, occurring at levels up to about 1–3%. GLC conditions for hydrogenated samples are often not suitable for refined oils because of overlap problems, but this time in the 18∶3 region. Through careful selection of stationary phase and temperature program optimization (Drylab®GC), we have developed a single method that is suitable for hydrogenated, as well as refined, processed oils. The accuracy was checked withcis andtrans fatty acid fractions isolated by silverion exchange high-performance liquid chromatography. Thetrans values obtained with the optimized method are in good agreement with the results obtained for the isolated fractions. We propose that recommended methods describe GLC conditions in terms of separation criteria rather than recommending only a fixed combination of stationary phase and temperature program. 相似文献
19.
The monoenoic methyl esters from numerous fats and oils which contained appreciablecis-9-hexadecenoic acid (cis-9-16∶1) were isolated by liquid-solid chromatography on silver nitrate-silica gel. Analysis of the monoenes by packed and
capillary column gas-liquid chromatography showed that significant amounts ofcis-11-octadecenoic acid (cis-11-18∶1) were present in all samples. The amount ofcis-11-18∶1 found in the monoenoic methyl esters increased proportionally to logarithmic increases in thecis-9-16∶1 level. Most analyses reported in the literature also show this proportionality. This mathematical relationship suggests
that chain elongation ofcis-9-16∶1 tocis-11-18∶1 is a biosynthetic pathway operative in a wide variety of species. 相似文献
20.
Summary A quantitative method for the determination of traces of free gossypol in oils and fatty acids was developed. The method is
based on the concentration of gossypol by extraction and quantitative paper chromatography of the extract. The method is specific
for free gossypol and is not subject to interferences. The new method is both accurate and reproducible. The lower limit of
detection is 10 p.p.m. The method is intended primarily for p.p.m. levels but is suitable for all concentrations. With slight
modifications the method is applicable to meals.
Presented at the fall meeting of the American Oil Chemists’ Society, Cincinnati, O., September 30 to October 2, 1957. 相似文献