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1.
Kenneth D. Carlson Robert Kleiman Marvin O. Bagby 《Journal of the American Oil Chemists' Society》1994,71(2):175-182
Lesquerella gordonii (Gray) Wats andLimnanthes alba Benth. (Meadowfoam) are species being studied as new and alternative crops. Triglyceride oil from lesquerella contains 55–60%
of the uncommon 14-hydroxy-cis-11-eicosenoic acid. Meadowfoam oil has 95% uncommon acids, includingca. 60%cis-5-eicosenoic acid. Both oils are predominantly unsaturated (3% saturated acids), and have similar iodine values (90–91),
from which oxirane values of 5.7% are possible for the fully epoxidized oils. Each oil was epoxidized withm-chloro-peroxybenzoic acid, and oxirane values were 5.0% (lesquerella) and 5.2% (meadowfoam). The epoxy acid composition of
each product was examined by gas chromatography of the methyl esters, which showed that epoxidizedL. gordonii oil contained 55% 11,12-epoxy-14-hydroxyeicosanoic acid, and epoxidized meadowfoam oil contained 63% 5,6-epoxyeicosanoic
acid, as expected for normal complete epoxidation. Mass spectrometry of trimethylsilyloxy derivatives of polyols, prepared
from the epoxidized esters, confirmed the identity of the epoxidation products and the straightforward nature of the epoxidation
process. Synthesis and characterization of these interesting epoxy oils and derivatives are discussed. 相似文献
2.
Nikolaus Weber Klaus Vosmann Eberhard Fehling Kumar D. Mukherjee Dieter Bergenthal 《Journal of the American Oil Chemists' Society》1995,72(3):361-368
A novel process has been described recently for the preparation of hydroxylated fatty acids (HOFA) and HOFA methyl esters
from plant oils. HOFA methyl esters prepared from conventional and alternative plant oils were characterized by various chromatographic
methods (thin-layer chromatography, high-performance liquid chromatography, and gas chromatography) and gas chromatography-mass
spectrometry as well as1H and13C nuclear magnetic resonance spectroscopy. HOFA methyl esters obtained fromEuphorbia lathyris seed oil, low-erucic acid rapeseed oil, and sunflower oil contain as major constituents methylthreo-9,10-dihydroxy octadecanoate (derived from oleic acid) and methyl dihydroxy tetrahydrofuran octadecanoates, e.g., methyl
9,12-dihydroxy-10,13-epoxy octadecanoates and methyl 10,13-dihydroxy-9,12-epoxy octadecanoates (derived from linoleic acid).
Other constituents detected in the products include methyl esters of saturated fatty acids (not epoxidized/derivatized) and
traces of methyl esters of epoxy fatty acids (not hydrolyzed). The products that contain high levels of monomeric HOFA may
find wide application in a variety of technical products. 相似文献
3.
A. C. Fogerty A. R. Johnson Judith A. Pearson F. S. Shenstone 《Journal of the American Oil Chemists' Society》1965,42(10):885-887
Methyl malvalate has been prepared from mixed methyl esters ofSterculia foetida seed oil fatty acids by reversed-phase liquid-liquid partition chromatography, and confirmatory evidence adduced for its
structure. 相似文献
4.
Volker Spitzer Werner Tomberg Mônica Zucolotto 《Journal of the American Oil Chemists' Society》1996,73(5):569-573
Besides some usual fatty acids, the seed oil ofSabastiana brasiliensis (Euphorbiaceae) contains up to 39% (estimated by ultraviolet spectroscopy) of α-parinaric acid (cis, trans, trans, cis-9, 11, 13, 15-octadecatetraenoic acid). The fatty acids were analyzed by gas chromatography and gas chromatography/mass spectrometry
as their methyl esters. The structure of α-parinaric acid was proven by a combination of chemical and spectroscopic methods,
conducted with the crude oil, the methyl ester mixture, and the isolated fatty acid methyl ester. Complete assignment of the1H and13C nuclear magnetic resonance (NMR) shifts of α-parinaric acid was carried out by two-dimensional NMR experiments
Presented in part at the 21st world Congress and Exhibition of the International Society for Fat Research (ISF), October 1–6,
1995, The Hague, The Netherlands. 相似文献
5.
Nanzad Tsevegsüren Kurt Aitzetmüller 《Journal of the American Oil Chemists' Society》1996,73(12):1681-1684
Seeds of nine Central Asian species of Boraginaceae were investigated for the first time for their oil content and for the
fatty acid composition of their seed oils by capillary gas chromatography. Levels of γ-linolenic acid ranged from 6.6 to 13.0%
and levels of stearidonic acid ranged from 2.4 to 21.4% of total seed fatty acids. The seed oil ofHackelia deflexa exhibited the highest stearidonic acid content (21.4%) that has been found so far in nature. Other high contents of this
fatty acid were in threeLappula species (17.2 to 18.1%). Seed oils ofCynoglossum divaricatum andAmblynotus rupestris contain considerable amounts ofcis-11-eicosenoic (5.3 to 5.8%) andcis-13-docosenoic acid (7.0 to 9.7%) besides γ-linolenic (10.2 to 13.0%) and stearidonic acid (2.4 to 6.5%), which distinguish
these oils from those of other Boraginaceae genera.
This paper was presented as a poster at 10th Minisymposium and Workshop on Plant Lipids, Sept. 3–6, 1995, in Berne, Switzerland. 相似文献
6.
In the presence of an immobilized lipase fromCandida antacrtica (Novozym 435R) fatty acids are converted to peroxy acids by the reaction with hydrogen peroxide. In a similar reaction, fatty acid esters
are perhydrolyzed to peroxy acids. Unsaturated fatty acid esters subsequently epoxidize themselves, and in this way epoxidized
plant oils can be prepared with good yields (rapeseed oil 91%, sunflower oil 88%, linseed oil 80%). The hydrolysis of the
plant oil to mono- and diglycerides can be suppressed by the addition of a small amount of free fatty acids. Rapeseed oil
methyl ester can also be epoxidized; the conversion of C=C-bonds is 95%, and the composition of the epoxy fatty acid methyl
esters corresponds to the composition of the unsaturated methyl esters in the substrate.
Based partly on a lecture at the 86th AOCS Annual Meeting & Expo, San Antonio, Texas, May 7–11, 1995. 相似文献
7.
Yandi D. Liu Robert B. Longmore John E. D. Fox 《Journal of the American Oil Chemists' Society》1996,73(12):1729-1731
The seed oil ofSantalum spicatum contains a significant amount of ximenynic acid,trans-11-octadecen-9-ynoic acid, a long-chain acetylenic fatty acid, as a major component (34%). The identity oftrans-ximenynic acid was confirmed after isolation by ultraviolet, infrared, and nuclear magnetic resonance (NMR) (1H- and13C-) spectroscopy and by gas chromatography/mass spectrometry (GC/MS). Thecis isomer of ximenynic acid was also found (<1%) in some samples. Thecis andtrans isomers were characterized by GC/MS comparison of their methyl esters and 4,4-dimethyloxazoline derivatives. 相似文献
8.
W. M. N. Ratnayake R. Hollywood E. O'Grady J. L. Beare-Rogers 《Journal of the American Oil Chemists' Society》1990,67(11):804-810
A combined capillary gas liquid chromatography (GLC) and infrared spectrophotometry (IR) method is described for the determination
ofcis andtrans-octadecenoic acids in margarines made from partially hydrogenated vegetable oils. The totaltrans-unsaturation of margarine fatty acid methyl esters determined by IR, with methyl elaidate as the external standard, was correlated
to the capillary GLC weight percentages of the componenttrans fatty acid methyl esters by the mathematical formula: IRtrans=%18∶1t+0.84×%18.2t+1.74×%18∶2tt+ 0.84×%18∶3t where 0.84, 1.74 and 0.84 are the correction factors which relate the GLC weight percentages to the IRtrans-equivalents for mono-trans-octadecadienoic (18∶2t),trans, trans-octadecadienoic (18∶2tt) and mono-trans-octadecatrienoic (18∶3t) acids, respectively. This formula forms the basis for the determination of totaltrans-andcis-octadecenoic acids in partially hydrogenated vegetable oils. From the weight percentages of 18∶2t, 18∶2tt and 18∶3t determined by capillary GLC on a cyanosilicone liquid phase and the totaltrans-unsaturation by IR, the percentage of the totaltrans-octadecenoic acids (18∶1t) is calculated using the formula. The difference between the total octadecenoic acids (18∶1), determined by capillary GLC,
and the 18∶1t gives the totalcis-octadecenoic acids.
Presented in part at the 81st Annual Meeting of the American Oil Chemists' Society, Baltimore, Maryland, April 22–25, 1990. 相似文献
9.
J.-F. Butaud P. Raharivelomanana J.-P. Bianchini E. M. Gaydou 《Journal of the American Oil Chemists' Society》2008,85(4):353-356
The sandalwood kernels of Santalum insulare (Santalaceae) collected in French Polynesia give seed oils containing significant amounts of ximenynic acid, E-11-octadecen-9-oic acid (64–86%). Fatty acid (FA) identifications were performed by gas chromatography/mass spectrometry
(GC/MS) of FA methyl esters. Among the other main eight identified fatty acids, oleic acid was found at a 7–28% level. The
content in stearolic acid, octadec-9-ynoic acid, was low (0.7–3.0%). An inverse relationship was demonstrated between ximenynic
acid and oleic acid using 20 seed oils. Results obtained have been compared to other previously published data on species
belonging to the Santalum genus, using multivariate statistical analysis. The relative FA S. insulare composition, rich in ximenynic acid is in the same order of those given for S. album or S. obtusifolium. The other compared species (S. acuminatum, S. lanceolatum, S. spicatum and S. murrayanum) are richer in oleic acid (40–59%) with some little differences in linolenic content. 相似文献
10.
M. Adam M. Chew S. Wasserman A. McCollum R. E. McDonald M. M. Mossoba 《Journal of the American Oil Chemists' Society》1998,75(3):353-358
An attenuated total reflection infrared spectroscopy procedure was collaboratively studied among two sets of five laboratories
for quantitating the total trans fatty acid levels in neat (without solvent) hydrogenated vegetable oils, measured as triacylglycerols in one study, and as
fatty acid methyl ester derivatives in the other. Unlike the fatty acid methyl esters, the triacylglycerols required no derivatization
but had to be melted prior to measurement. To obtain a symmetric absorption band at 966 cm−1 on a horizontal background, the single-beam spectrum of the trans-containing fat was "ratioed" against that of a refined oil or a reference material that contained only cis double bonds. A single-bounce horizontal attenuated total reflection cell that requires 50 μL of undiluted test samples was
used for oils, melted fats, or their methyl esters. For fatty acid methyl esters, the reproducibility relative standard deviations
were in the range of 0.9 to 18.46% for 39.08 to 3.41% trans, determined as methyl elaidate per total fatty acid methyl esters. For five pairs of triacylglycerol blind duplicates, the
reproducibility and repeatability relative standard deviations were in the ranges of 1.62 to 18.97%, and 1.52 to 13.26%, respectively,
for 39.12 to 1.95% trans, determined as trielaidin per total triacylglycerols. Six pairs of spiked triacylglycerol blind duplicates (quality assurance
standards) exhibited high accuracy in the range of 0.53 to 40.69% trans and averaged a low bias of 1.3%. These statistical analysis results were compared to those collaboratively obtained by the
recently adopted AOCS Cd14-95 and AOAC 994.34 Infrared Official Methods. 相似文献
11.
A fractionally distilled C14−C16 fatty acid methyl ester, derived from palm oil, was sulfonated with gaseous SO3 in a falling film reactor to form an α-sulfo fatty acid methyl ester (α-SF; unbleached and unneutralized form). The included
dark-colored impurities were then separated from α-SF as a diethyl ether-insoluble matter. After purification by thin-layer
chromatography, the colored species were analyzed by ion-exchange chromatography, gel-permeation chromatography, and nuclear
magnetic resonance spectrometry. These data suggested that the colored species were polysulfonated compounds with conjugated
double bonds. Minor components in the raw fatty acid methyl ester, found by gas chromatography/mass spectrometry, were spiked
into the purified methyl palmitate and then sulfonated. The unsaturated methyl ester and hydroxy ester showed the worst color
results. The methyl oleate and methyl 12-hydroxystearate were then sulfonated and analyzed. Deep black products were obtained,
which showed the same properties as the colored species in α-SF. It was concluded that low levels of unsaturated fatty acid
methyl esters and hydroxy esters in the fatty acid methyl ester are the main causes of the coloring. 相似文献
12.
Robert L. Wolff 《Journal of the American Oil Chemists' Society》1992,69(2):106-110
The fatty acid compositions of rapeseed and soybean oils marketed in France have been determined by gas liquid chromatography
on a fused-silica capillary column coated with a 100% cyanopropyl polysiloxane stationary phase. Under the operating conditions
employed, methyl esters of linolenic acid geometrical isomers could be separated and quantitated easily without any other
complementary technique. With only one exception, all samples under study (eight salad oils and five food samples) contain
geometrical isomers of linolenic acid in measurable, although variable, amounts. Totaltrans-18:3 acids may account for up to 3% of total fatty acids. This value corresponds to a degree of isomerization (percentage
oftrans isomers relative to total octadecatrienoic acids) of 30%. Examination of our data indicates that the distribution pattern
of linolenic acid geometrical isomers does not depend on the degree of isomerization. The two main isomers always have thec,c,t and thet,c,c configurations. These isomers occur in the almost invariable relative proportions of 47.8±1.7% and 41.1±1.0%, respectively.
The third mono-trans isomer is present in lower amounts−6.5±0.7%. The only di-trans isomer that can be quantitated with sufficient accuracy is thet,c,t isomer (4.9±1.5%). Mono-trans isomers of linoleic acid are also present in these oils. However, their maximum percentages are lower than those determined
for linolenic acid geometrical isomers. In the oils showing the highest degrees of isomerization,trans isomers of linoleic acid account for 0.5% (rapeseed oils) and 1% (soybean oils) of total fatty acids. Taking into account
all data, it would appear that the probability of isomerization of linolenic acid is about 13–14 times that of linoleic acid. 相似文献
13.
K. D. Carlson A. Chaudhry R. E. Peterson M. O. Bagby 《Journal of the American Oil Chemists' Society》1990,67(8):495-498
To conduct product development research onLesquerella seed oils, we explored methods to obtain >100 g quantities of lesquerolic (14-hydroxy-cis-11-eicosenoic) acid. Preliminary experiments with open-column silica gel chromatography showed thatL. fendleri oil could be separated into 3 triglyceride (TG) fractions. The first (10%) contained nonhydroxy 16-(13%) and 18-carbon acids
(65% 18∶1,2,3). The second fraction (15%) contained monolesquerolins (39% lesquerolic acid). The major TG fraction (73%) was
mainly dilesquerolins (66% lesquerolic acid) showing that a hydroxy acid-enriched TG oil was obtainable by this procedure.
Silica gel chromatography easily separatedL. fendleri fatty acid methyl esters (FAME) into a hydroxy-free ester fraction (40–44%) consisting largely of 18∶1 (39%), 18∶2 (19%)
and 18∶3 (31%), and a hydroxy ester fraction (56–60%) that was largely methyl lesquerolate (94%) with small amounts of auricolate
(5%) (14-hydroxy-cis-11,cis-17-eicosadienoate) and traces of 18-carbon hydroxy esters. This process for isolating the hydroxy FAME ofLesquerella oil was scaled up 15-to 100-fold with a preparative high performance liquid chromatograph. Thirty-gram samples ofL. gordonii FAME were dissolved in eluting solvent, pumped onto the high performance liquid chromatography (HPLC) silica column and eluted
with 97∶3 hexane/ethyl acetate. In an 8-hr period, up to 200 g of methyl lesquerolate could be obtained with a purity >98%,
the only contaminants being methyl auricolate and methyl ricinoleate.
Presented at the AOCS meeting in Phoenix, AZ, May 1988.
The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of
Agriculture over other firms or similar products not mentioned. 相似文献
14.
E. L. Schneider Sook P. Loke D. T. Hopkins 《Journal of the American Oil Chemists' Society》1968,45(9):585-590
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. 相似文献
15.
Robert L. Wolff Laurent G. Deluc Anne M. Marpeau 《Journal of the American Oil Chemists' Society》1996,73(6):765-771
The seed oils from twenty-five Conifer species (from four families—Pinaceae, Cupressaceae, Taxodiaceae, and Taxaceae) have
been analyzed, and their fatty acid compositions were established by capillary gas-liquid chromatography on two columns with
different polarities. The oil content of the seeds varied from less than 1% up to 50%. Conifer seed oils were characterized
by the presence of several Δ5-unsaturated polymethylene-interrupted polyunsaturated fatty acids (Δ5-acids) with either 18
(cis-5,cis-9, 18∶2,cis-5,cis-9,cis-12 18∶3, andcis-5,cis-9,cis-12,cis-15 18∶4 acids) or 20 carbon atoms (cis-5,cis-11 20∶2,cis-5,cis-11,cis-14, 20∶3, andcis-5,cis-11,cis-14,cis-17 20∶4 acids). Pinaceae seed oils contained 17–31% of Δ5-acids, mainly with 18 carbon atoms. The 20-carbon acids present
were structurally derived from 20∶1n-9 and 20∶2n-6 acids. Pinaceae seed oils were practically devoid of 18∶3n-3 acid and did
not contain either Δ5-18∶4 or Δ5-20∶4 acids. Several Pinaceae seeds had a Δ5-acid content higher than 50 mg/g of seed. The
only Taxaceae seed oil studied (Taxus baccata) had a fatty acid composition related to those of Pinaceae seed oils. Cupressaceae seed oils differed from Pinaceae seed
oils by the absence of Δ5-acids with 18 carbon atoms and high concentrations in 18∶3n-3 acid and in Δ5-acids with 20 carbon
atoms (Δ5-20∶3 and Δ5-20∶4 acids). Δ5-18∶4 Acid was present in minute amounts. The highest level of Δ5-20∶4 acid was found
inJuniperus communis seed oil, but the best source of Δ5-acids among Cupressaceae wasThuja occidentalis. Taxodiaceae seed oils had more heterogeneous fatty acid compositions, but the distribution of Δ5-acids resembled that found
in Cupressaceae seed oils. Except forSciadopytis verticillata, other Taxodiaceae species are not interesting sources of Δ5-acids. The distribution profile of Δ5-acids among different
Conifer families appeared to be linked to the occurrence of 18∶3n-3 acid in the seed oils. 相似文献
16.
Olives were collected from various districts of Turkey (North and South Aegean sub-region, Bursa-Akhisar, South East Anatolia
region) harvested over seven (2001–2007) seasons. The aim of this study was to characterize the chemical profiles of the oils
derived from single variety Turkish olives including Ayvalik, Memecik, Gemlik, Erkence, Nizip Yaglik and Uslu. The olive oils
were extracted by super press and three phase centrifugation from early harvest olives. Chosen quality indices included free
fatty acid content (FFA), peroxide value (PV) and spectrophotometric characteristics in the ultraviolet (UV) region. According
to the FFA results, 46% (11 out of 24 samples) were classified as extra virgin olive oils; whereas using the results of PV
and UV, over 83% (over 19 of the 24 samples) had the extra virgin olive oil classification. Other measured parameters included
oil stability (oxidative stability, chlorophyll pigment, pheophytin-α), cis–trans fatty acid composition and color index. Oxidative stability among oils differed whereas the cis–trans fatty acid values were within the national and international averages. Through the application of two multivariate statistical
methods, Principal component and hierarchical analyses, early harvest virgin olive oil samples were classified according to
the geographical locations categorized in terms of fatty acid profiles. Such statistical clustering gave rise to defined groups.
These data provide evidence of the variation in virgin olive oil quality, especially early harvest and cis–trans isomers of fatty acid profiles from the diverse agronomic conditions in the olive growing regions of Turkey. 相似文献
17.
Z. M. Zarins R. K. Willich R. O. Feuge 《Journal of the American Oil Chemists' Society》1983,60(12):2007-2008
Solubilities of six cottonseed oil fatty acid methyl esters in metha-nol have been determined. The esters were: methyl oleate, methyl linoleate, methyl malvalate, methyl dihydromalvalate, methyl sterculate and methyl dihydrosterculate. The solubility/temperature data are presented in graphical and tabular form. 相似文献
18.
Medium-chain fatty acid-rich glycerides by chemical and lipase-catalyzed polyester-monoester interchange reaction 总被引:4,自引:0,他引:4
Medium-chain triglycerides (MCT) that contain caprylic acid (C8:0) and capric acid (C10:0) have immense medicinal and nutritional importance. Coconut oil can be used as a starting raw material for the production
of MCT. The process, based on the interchange reaction between triglycerides and methyl esters of medium-chain fatty acids
by chemical catalyst (sodium methoxide) or lipase (Mucor miehei) catalyst, appears to be technically feasible. Coconut oils with 25–28.3% (w/w) and 22.1–25% (w/w) medium-chain fatty acids
have been obtained by chemical and lipase-catalyzed interchange reactions. Coconut olein has also been modified with C8:0 and C10:0 fatty acids, individually as well as with their mixtures, by chemical and lipase-catalyzed interchange reactions. Coconut
olein is a better raw material than coconut oil for production of mediumchain fatty acid-rich triglyceride products by both
chemical and lipase-catalyzed processes. 相似文献
19.
Robert L. Wolff Jean-Louis Sébédio 《Journal of the American Oil Chemists' Society》1994,71(2):117-126
Heating of borage oil, either under vacuum as a model or during steam-vacuum deodorization, produces artifacts that are geometrical
isomers of γ-linolenic acid (cis-6,cis-9,cis-12 18∶3 acid). In a first approach, we have studied the behavior of these fatty acids in the form of either methyl or isopropyl
esters on two capillary columns (CP-Sil 88 and DB-Wax). From this study, it appears that the DB-Wax capillary column is the
best suited analytical tool to study in some detail γ-linolenic acid geometrical isomers. In a second approach, the structure
of these isomers was formally established by combining several analytical techniques: Argentation thin-layer chromatography,
comparison of the equivalent chainlengths with those of isomers present in NO2-isomerized borage oil on two different capillary columns, partial hydrazine reduction, oxidative ozonolysis, gas chromatography
coupled with mass spectrometry and gas chromatography coupled with Fourier transform infrared spectroscopy. The two main isomers
that accumulate upon heat treatments are thetrans-6,cis-9,cis-12 andcis-6,cis-9,trans-12 18∶3 acids with minor amounts ofcis-6,trans-9,cis-12 18∶3 acid. One di-trans isomer, supposed to be thetrans-6,cis-9,trans-12 18∶3 acid, is present in low although noticeable amounts in some of the heated oils. The content of these artificial fatty
acids increases with increasing temperatures and duration of heating. The degree of isomerization (DI) of γ-linolenic acid
is less than 1% when the oil is deodorized at 200°C for 2 h. Heating at 260°C for 5 h increases the DI up to 74%. Isomerization
of γ-linolenic acid resembles that of α-linolenic (cis-9,cis-12,cis-15 18∶3) acid in several aspects: The same kinds and numbers of isomers are formed, and similar degrees of isomerization
are reached when the octadecatrienoic acids are heated under identical conditions. It seems that the reactivity of a double-bondvis-à-vis cis-trans isomerization is linked to its relative position, central or external, and not to its absolute position (Δ6, 9, 12 or 15). 相似文献
20.
Antti Aro Truus Kosmeijer-Schuil Peter van de Bovenkamp Paul Hulshof Peter Zock Martijn B. Katan 《Journal of the American Oil Chemists' Society》1998,75(8):977-985
Trans fatty acids in foods are usually analyzed by gas-liquid chromatography (GLC) of fatty acid methyl esters (FAME). However,
this method may produce erroneously low values because of insufficient separation between cis and trans isomers. Separation can be optimized by preceding silver-ion thin-layer chromatography (Ag-TLC), but this is laborious. We
have developed an efficient method for the separation of 18-carbon trans fatty acid isomers by combining GLC of FAME with GLC of fatty acid 4,4-dimethyloxazoline (DMOX) derivatives. We validated
this method against conventional GLC of FAME, with and without preceding Ag-TLC. Fatty acid isomers were identified by comparison
with standards, based on retention times and mass spectrometry. Analysis of DMOX derivatives allowed the 13t, 14t, and 15t isomers to be separated from the cis isomers. The combination of the GLC analyses of FAME and DMOX derivatives gave results comparable with those obtained by
GLC of FAME after preceding Ag-TLC, while saving about 100 h of manpower per 25 samples. It allowed the identification and
quantitation of 11 trans and 8 cis isomers and resulted in 25% higher values for total C18:1
trans, compared with the analysis of FAME alone. The combination of DMOX and FAME analyses, as applied to the analysis of 14 foods
that contained ruminant fat and partially hydrogenated vegetable and fish oils, indicated that the most common isomers were
11t in ruminant fats, 9t in partially hydrogenated fish fats, and either 9t or 10t in partially hydrogenated vegetable fats. The combination of GLC analyses of FAME and DMOX derivatives of fatty acids improves
the quantitation of 18-carbon fatty acid isomers and may replace the laborious and time-consuming Ag-TLC. 相似文献