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1.
P. Ruiz-Sala M. T. G. Hierro I. Martínez-Castro G. Santa-María 《Journal of the American Oil Chemists' Society》1996,73(3):283-293
The separation and identification of the components in milk fat, which are mainly triglycerides, is a challenge due to its
complex composition. A reverse-phase high-performance liquid chromatography (HPLC) method with gradient elution and light-scattering
detection is described in this paper for the triglyceride analysis in ewes’ milk fat. Triglyceride identification was carried
out by combining HPLC, gas-liquid chromatography (GLC), and the calculated equivalent carbon numbers of several triglyceride
standards. Quantitation of partially resolved peaks in the HPLC chromatogram was accomplished by applying a peak deconvolution
program. Forty-four fatty acids were identified by GLC analysis, but only 19 were used for the following prediction of triglyceride
molecular species; 181 triglycerides were identified, some of which were grouped at the same peak and needed application of
the deconvolution program. Consequently, coefficients of variation were close to or lower than 5%. Moreover, the triglyceride
composition of ewe, cow, and goat milk fat were compared by using these methods. These results show that ewe milk fat is richer
in short- and medium-chain triglycerides, and cow milk fat is richer in long-chain and unsaturated triglycerides. 相似文献
2.
3.
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
4.
Jean Pontillon 《Journal of the American Oil Chemists' Society》1995,72(8):861-866
The combination of two routine methods is proposed to determine the content of milk fat (MF) in chocolates, which is applicable
even in the presence of lauric fats or others. The content of MF is obtained from the sum of C40, C42, and C44 medium-chain triglycerides, determined by capillary gas-liquid chromatography (GLC). A new method, based on methyl esters
of lauric acid and on minor acids situated between myristic and palmitic, is proposed. It enables detection and estimation
of potential lauric fats, as well as the determination of the actual content of MF. The influence of other vegetable and animal
fats is discussed. We analyzed 45 MF samples extracted from industrial milk powders and from pure or fractionated MF for chocolate
manufacturing or pastry by GLC of triglycerides. We also analyzed by capillary GLC the methyl esters from 22 of those fats.
Mixtures of these 22 MF samples with a cocoa butter also were used for chromatographic analyses of methyl esters and triglyceride.
Results from the various analytical methods have been presented. 相似文献
5.
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
6.
Robert L. Wolff 《Journal of the American Oil Chemists' Society》1995,72(3):259-272
Thetrans-18:1 acid content and distribution in fats from ewe and goat milk, beef meat and tallow were determined by a combination
of capillary gas-liquid chromatography and argentation thin-layer chromatography of fatty acid isopropyl esters. Thetrans isomers account for 4.5 ± 1.1% of total fatty acids in ewe milk fat (seven samples) and 2.7±0.9% in goat milk fat (eight
samples). In both species, as in cow, the main isomer is vaccenic (trans-11 18:1) acid. The distribution profile oftrans-18:1 acids is similar among the three species. The contribution of ewe and goat milk fat to the daily intake oftrans-18:1 acids was estimated for people from southern countries of the European Economic Community (EEC): France, Italy, Greece,
Spain, and Portugal. It is practically negligible for most of these countries, but in Greece, ewe and goat milk fat contributeca. 45% of the daily consumption oftrans-18:1 acids from all dairy products (0.63 g/person/day for a total of 1.34 g/person/day). Thetrans-18:1 acid contents of beef meat fat (ten retail cuts, lean part) and tallow (two samples) are 2.0 ± 0.9% and 4.6%, respectively,
of total fatty acids (animals slaughtered in winter). Here too, the main isomer is vaccenic acid. Othertrans isomers have a distribution pattern similar to that of milk fat. Beef meat fat contributes less than one-tenth of milk fat
to thetrans-18:1 acid consumed. The daily per capita intake oftrans-18:1 acids from ruminant fats is 1.3–1.8 g for people from most countries of the EEC, Spain and Portugal being exceptions
(ca. 0.8 g/person/day). In France, the respective contributions of ruminant fats and margarines to the daily consumption oftrans-18:1 acids are 1.7 and 1.1 g/person/day (60 and 40% of total, respectively). These proportions, based on consumption data,
were confirmed by the analysis of fat from milk of French women (ten subjects). The mean content oftrans-18:1 acids in human milk is 2.0 ± 0.6%, with vaccenic acid being the major isomer. Based on the relative levels of thetrans-16 18:1 isomer, we could confirm that milk fat is responsible for the major part of the daily intake oftrans-18:1 acids by French people. The daily individual intake oftrans-18:1 isomers from both ruminant fats and margarines for the twelve EEC countries varies from 1.5 g in Spain to 5.8 g in Denmark,
showing a well-marked gradient from the southwest to the northeast of the EEC. 相似文献
7.
Robert L. Wolff Frederic F. Vandamme 《Journal of the American Oil Chemists' Society》1992,69(12):1228-1231
Petroselinic (cis-6 18:1) and oleic (cis-9 18:1) acids that occur together in Umbelliferae seeds can be resolved by gasliquid chromatography (GLC) of their methyl
or isopropyl esters on a 50 m × 0.25 mm fused-silica capillary column coated with a 100% cyanopropyl polysiloxane stationary
phase (CP Sil 88). The use of isopropyl esters instead of methyl esters increases the difference between equivalent chainlengths
from 0.06 carbon unit up to 0.08. This is sufficient to obtain an almost base-line resolution between the two components.cis-Vaccenic acid is completely separated from oleic acid in both derivative forms. GLC of fatty acid isopropyl esters on an
appropriate capillary column thus appears to be the simplest means to simultaneously and accurately quantitate petroselinic,
oleic andcis-vaccenic acids. 相似文献
8.
Improvement in the resolution of individualtrans-18:1 isomers by capillary gas-liquid chromatography: Use of a 100-m CP-Sil 88 column 总被引:1,自引:0,他引:1
Robert L. Wolff Corinne C. Bayard 《Journal of the American Oil Chemists' Society》1995,72(10):1197-1201
Doubling the length of a CP-Sil 88 capillary column (Chrompack, Middelburg, The Netherlands) from 50 to 100 m remarkably improves
the resolution of individualtrans-18:1 isomers from either ruminant fats or partially hydrogenated oils. Although the use of a 50-m column gives interesting
results, it does not allow sufficient resolution of thetrans-10 andtrans-11 18:1 isomers. Moreover, thetrans-6 totrans-9 18:1 isomers emerge as a single group of peaks, whereas thetrans-12 isomer is only partly resolved from the adjacenttrans-11 andtrans-13 plustrans-14 isomers. With the 100-m column, thetrans-9,trans-10, andtrans-12 18:1 isomers are almost base-line resolved from other isomers. However, with both columns, it is not possible to separate
the critical pair oftrans-13 andtrans-14 18:1 acids which co-elute under a single peak. Despite this minor drawback, the 100-m CP-Sil 88 column appears to be of
great interest for the separation and the quantitation of most individualtrans-18:1 acids. Except for the use of argentation thin-layer chromatography, there is no need for complementary techniques, such
as ozonolysis. This simple and powerful tool may be applied to ruminant fats, partially hydrogenated oils, and human tissue
lipids. 相似文献
9.
Takashi Iida Takako Itoh Kayoko Hagiwara Frederic C. Chang Junichi Goto Toshio Nambara 《Lipids》1989,24(12):1053-1055
A method for the simultaneous analysis of unconjugated and glycine-conjugated bile acids by means of capillary gas-liquid
chromatography without need for prior deconjugation is described. The method involves: i) the use of an aluminum-clad fused-silica
capillary column coated with a very thin film (0.1 μm) of a highly thermostable bonded and crosslinked methyl polysiloxane,
and ii) the analysis of the bile acids as their methyl ester-dimethylethylsilyl ether derivatives. This method, used to separate
the major free and glycine-conjugated bile acids from human gall bladder bile, should be applicable for the analysis of other
biological fluids. 相似文献
10.
Shirasawa S Shiota M Arakawa H Shigematsu Y Yokomizo K Shionoya N Okamoto T Miyazaki Y Takahashi S Himata K 《Journal of oleo science》2007,56(8):405-415
Excessive intake of trans-fatty acids increases the risk of cardiovascular disease. Much attention is drawn to the consumption of trans-fatty acids worldwide, and regulations for trans-fatty acids are instituted in several countries. Precise and convenient methods for determination of trans-fatty acid level are required, but there is no standard method using capillary Gas Chromatography in Japan. Therefore, for the new standard method, collaborative studies were carried out. The results were as follows: 1) Heptadecanoate (C17:0 free fatty acid) was chosen for internal standard substance. 2) Two Gas Chromatography columns, SP2560 (100 m) column (100% cyanopropyl polysiloxane liquid phase) and TC-70 (60 m) column (70% cyanopropyl polysilphenylene-siloxane liquid phase), were examined in the collaborative studies. We measured the edible oil samples containing 2-45 g/100 g of trans-fatty acids, and trans-fatty acid contents were quantitatively the same with both columns. The range of reproducibility coefficient of variation were below 10%. 3) Fats and oils sampled were soybean, rapeseed, palm, palm kernel, beef tallow, pork fat and their hydrogenated forms, for which good peak resolution was achieved. From the above results, the technique evaluated in the present study was considered to be suitable for determination of the content of trans-fatty acids in fats and oils exclusive of fish oil and milk fat. 相似文献
11.
S. H. Ojanperä 《Journal of the American Oil Chemists' Society》1978,55(2):290-292
The use of a glass capillary column coated with Silar 10 CP for gas liquid chromatographic analysis of geometric and positional
isomers of monoethylenic fatty acids of a partially hydrogenated herring oil is reported. The results are in agreement with
previous studies performed by different methods and demonstrate the usefulness of this technique in detecting and determining
many types of isomeric fatty acids. 相似文献
12.
13.
A method has been devised which gives the distribution of saturated and unsaturated fatty acids. It involves fractionation
of the triglycerides into groups on the basis of total unsaturation by employing chromatography on a silicic acid-silver nitrate
column. The glyceride composition of each fraction is then determined by gas-liquid chromatography (GLC) of the oxidized glycerides.
Using this method, the glyceride composition of lard and cocoa butter was determined to give quantitative amt of 24 and 18
glycerides, respectively. Duplicate analyses agreed to within ±0.5%. The fatty acid composition calculated from the glyceride
composition agreed to within ±1.5% with that of the original fat. This approach provides a new basis for the evaluation of
the glyceride tyes in natural fats and for the first time permits the quantitative determination of all the chemically different
glycerides of myristic, palmitic, stearic, oleic, linoleic and linolenic acids in a fat.
Presented at AOCS Meeting in Minneapolis, 1963. Issued at NRC 7947.
National Research Council Postdoctorate Fellow. Prairie Regional Laboratory, Saskatoon, Sask. 相似文献
14.
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
15.
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
16.
Monoenoic acid fractions were isolated from phosphatidycholine, phosphatidylethanolamine, triglycerides, and cholesteryl esters of hepatoma 7288CTC, host liver, and normal liver from animals maintained on chow and fat free diets. Hexadecanoate (16:1), octadecenoate (18:1), and eisosenoate (20:1) fractions were analyzed quantitatively for their isomeric composition. The fat free diet had little or no effect relative to the chow diet on the isomeric composition of 16:1, 18:1, and 20:1 from any lipid class in either heptoma, host liver, or normal liver. Host livers were reduced in palmitoleic acid, and oleic and eicos-11-enoic acids were increased relative to normal liver. The 16:1 fraction from triglyceride of normal liver, host liver, and hepatoma contained 90, 80, and 75% palmitoleic acid, respectively. The 20:1 fraction from triglycerides of normal liver, host liver, and hepatoma contained ca. 55, 70, and 60% eicos-11-enoic acid, respectively, with the remainder consisting of eicos-13-enoic acid. The proportion of vaccenic acid in the 18:1 fraction was 60, 50, 20, and 25% for phosphatidylethanolamine, phosphatidylcholine, triglycerides, and cholesteryl esters, respectively, with oleic acid making up the balance. In contrast, all hepatoma lipid classes exhibited the same proportion of oleic (70%) and vaccenic (30%) acids. These data appear to be the first to demonstrate lipid class specificity for isomeric octadecenoic acids in normal liver and the loss of this specificity in a neoplasm. 相似文献
17.
The electron capture gas liquid chromatography test method for chick edema factor has been modified by replacing the alumina
column step with an additional sulfuric acid cleanup and a caustic wash which permits a reduction in sample cleanup time.
Samples are subjected to double preliminary sulfuric acid cleanup and caustic wash and extracted each time with trimethyl
pentane. The final extract is washed with sulfuric acid and examined by electron capture gas chromatography. Gas chromatographic
peaks with retention times vs. Aldrin (Ra values) between 8 and 45 are indicative of the presence of chick edema factor. 相似文献
18.
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
19.
Robert L. Wolff 《Journal of the American Oil Chemists' Society》1994,71(8):907-909
Analysis of alpha-linolenic acid geometrical isomers in deodorized or heated oils by capillary gas-liquid chromatography (GLC)
on polar cyanoalkyl polysiloxane stationary phases requires some care to avoid interferences with other fatty acids. Depending
on the temperature of the column, thecis-11 20∶1 acid may elute before, with or after thecis-9,cis-12,cis-15 18∶3 acid during GLC. In some instances [temperature higher than 180°C with a CP Sil 88 column (Chrompack, Middelburg,
The Netherlands)], the 20∶1 acid coelutes with thetrans-9,cis-12,cis-15 18∶3 acid, leading to abnormally high levels of this last isomer. Consequently, the degree of isomerization of alpha-linolenic
acid will be over-estimated under such conditions. It is recommended that the behavior ofcis-11 20∶1 acid relative to temperature be checked carefully prior to the determination of alpha-linolenic acid geometrical
isomers by GLC. Temperatures lower than 160°C seem appropriate to separate all of these components from each other and fromcis-11 20∶1 acid in a 50 m×0.25 mm i.d. CP Sil 88 capillary column. 相似文献
20.
Heikki Kallio Kati Korkiasaari Olli Sjövall Jukka-Pekka Suomela Kaisa Linderborg 《Journal of the American Oil Chemists' Society》2006,83(5):407-413
TAG of butterfat were fractionated according to the type and degree of unsaturation into six fractions by silver-ion HPLC.
The fractions containing TAG with either cis-or trans-monoenoic FA were collected and fractionated further by reversed-phase HPLC to obtain fractions containing cis TAG of ACN:DB (acyl carbon number:double bonds) 48∶1, 50∶1, and 52∶1 as well as trans 48∶1, 50∶1, and 52∶1. The FA compositions of these fractions were elucidated by GC. The MW distribution of each fraction
was determined by ammonia negative-ion CI-MS. Each of the [M-H]− parent ions was fractionated further by collision-induced dissociation with argon, which gave information on the location
of cis-and trans-FA between the primary and secondary positions of TAG. The results suggest that the sn-positions of the monoenoic cis-and trans-FA depend on the two other FA present in the molecule. With 14∶0 FA in the TAG molecule, the 18∶1 FA in the sn-2 position are mostly present as cis-isomers. When there is no 14∶0 in the TAG molecule, the trans-18∶1 isomers seem to be more common in the sn-2 position. Also when other long-chain FA are present, the trans-isomers are more likely to be located in the secondary (sn-2) position. 相似文献