Schnellmethode zur Isolierung der Sterine aus Fetten und Ölen

Rapid Method for Isolation of Sterols from Fats and Oils Isolation of sterols from fats and oils mostly takes place by the very time-consuming solvent extraction of the unsaponifiable from the soap solution. The time required can be reduced to about 1 hour by a new developed procedure which makes possible to separate soaps and polar components of the fats from the saponified sample by aluminium oxide columns. The use of 250 mg of fat is sufficient for a following sterol examination by gas chromatography.     

Hauptkomponenten der 4-Methylsterin- und Triterpenfraktion von 12 Pflanzenfetten und ihr Einfluß auf die Sterinanalyse

Main Components of 4-Methyl-Sterol and Triterpene-Fraction of Twelve Vegetable Fats and their Influence on the Sterol Analysis 4-methylsterols and triterpenes are accompanying substances of the sterols in the unsaponifiable with partly very similar chromatographic properties. In 12 different vegetable fats both content and composition of the main components of these three substance groups were investigated and their influence on the sterol analysis was found out. For most fats a thin-layer chromatographic separation of the 4-methyl-sterols and triterpenes from the sterols is necessary to make possible an exact determination of the sterol content and the sterol composition by gas chromatography.     

Triacylglycerol profiling by using chromatographic techniques

Triacylglycerols (TGs) make up the major part of naturally occurring fats and oils. The composition and fine structure of TGs determine to a large extent the functionality of fats and oils as food ingredients and the physiological effects of fats and oils as component of the human diet. Analysis of intact TGs is usually performed by chromatographic methods. In this article the application of gas‐liquid chromatography, high‐performance chromatography in normal and reversed phase mode, thin‐layer chromatography and supercritical fluid chromatography for the qualitative and quantitative determination of TGs is reviewed. Emphasis is put on those factors that are decisive for obtaining reliable quantitative data. Furthermore, techniques for the stereospecific analysis of the fatty acid distribution along the glycerol backbone of TGs are presented briefly.     

毛细管气相色谱法分析TDI纯度的研究

建立了用毛细管气相色谱法测定甲苯二异氰酸酯纯度的方法。采用ＨＰ－５气相色谱柱、ＦＩＤ检测器、分流进样、面积归一化法,测定甲苯二异氰酸酯的纯度,其测试精度优于其它方法。     

Die Bestimmung der Erucasäure in Gegenwart von der Docosensäure

Determination of Erucic Acid in the Presence of Isomeric Docosenoic Acids In the countries belonging to the European Community the Erucic Acid Directive of 20. 7. 1976 restricts the level of erucic acid (not docosenoic acid) in edible oils and fats and foodstuffs to which fats and oils have been added to 5%. For the determination of the erucic acid content the EEC-Directive no. 80/891 specifies a procedure that enables the determination of erucic acid even in the presence of isomeric docosenoic acids. According to this procedure the methyl esters of fatty acids are first fractionated at –25°C on thin-layer plates containing silver nitrate. Thus, erucic acid (13-cis-docosenoic acid) is separated from isomeric docosenoic acids, such as cetoleic acid (11-cis-docosenoic acid) and trans-docosenoic acids, that are frequently found in crude and hydrogenated fish oils. The erucic acid content can be determined by gas chromatography of the eluted fractions after the addition of an internal standard. The method has been developed in collaboration with the Federal Center for Lipid Research. Their work concerned with the development of the method is reported. It includes the separation of pure docosenoic acid isomers and the determination of erucic acid content in a series of crude and hydrogenated fish oils.     

气相色谱法测定有机氯含量的不确定度评定

根据CNAS-GL06规范对气相色谱法测定盲样中丙体六六六含量的不确定度进行了评定,获得了标准曲线计算、标准溶液配制、样品测定过程、气相色谱仪本身等方面的不确定度。结果显示：测定结果符合要求,主要的不确定度来源是标准曲线计算、气相色谱仪本身和标准溶液配制过程。可通过增加标准曲线各点和样品的测量次数,严格按照规范操作配制标准溶液,测定样品前仔细检查气相色谱仪,等仪器充分稳定后再进行测定等措施来减少不确定度。     

气相色谱法在煤化工分析中的应用

目的：随着煤化工的发展，煤化工需要通过检查煤气内各种气体的含量与使用率。方法：色相气谱仪在煤化工逐渐运用起来，其通过分离气体，检测气体等方法。结果：分析气相色谱法能够获得整个煤气的气体成分。结论：煤气是多种气体混合体，它可以通过气相色谱法进行区分。     

Chemical analysis of polymerization products in abused fats and oils

For more than a decade, numerous analytical methods have been proposed for the detection and measurement of polymers in vegetable fats and oils. Many of the methods have been little more than laboratory curiosities, either because they were concerned with only very specific compounds or were too cumbersome and time consuming to become very popular. More recently, a number of methods in common use for analysis of fats and oils has been shown to be useful for indirectly measuring polymeric materials in heat abused oils. The present report shows, by the use of gel filtration chromatography, the validity of two of the indirect methods of estimating polymeric products of abused fats and oils. These methods are: the estimation of polymers through changes in the iodine value and the measurement of retention materials on a gas liquid chromatographic column. A new simplified internal standard gas liquid chromatographic procedure utilizing triglyceride standards also is presented. This latter method permits estimating the degree of degradation of vegetable fats and oils by any laboratory capable of determining the fatty acid composition of a sample by gas liquid chromatography. Presented at the AOCS Meeting, Ottawa, Canada, September 1972.     

Veränderungen der Fette unter Fritierbedingungen und deren analytische Erfassung Chemische Veränderungen der Fette beim Fritieren

Alterations of Fats Under Conditions of Deep-Frying and Their Analytical Detection: Artefacts Formation in Frying Fats During Deep-Frying During deep-frying the fats decompose with the formation of volatile, monomeric and polymeric compounds. Their amount and chemical structure depends on the fat blend, the temperature, the frying time, the frying good, and in a high degree on the accessibility of oxygen. As we have shown a quantitative determination of polymeric material in frying fats is possible using gel permeation chromatography. However, gel permeation chromatography determines the size of the molecules only and does not destinguish between various degrees of oxidation. For his purpose we apply liquid chromatography on silica gel which separates various fractions according to their polarity. In combination with a “moving wire” and flame ionisation detector a semi-quantitative evaluation of the amount of polar material in heated fats in possible. Liquid chromatography is applicable for preparative purposes and enables the non-destructive isolation of sufficient material for feeding experiments.     

Short‐chain fatty acids as marker for the degradation of frying fats and oils

The determination of fatty acid composition by gas chromatography as a routine task is established in most laboratories dealing with oils and fats. The scope of this method can be enlarged for a preliminary quality control of used frying fats and oils, which is commonly characterized by the determination of polar compounds and polymerized triacylglycerols. However, for screening purposes the determination of the short‐chain fatty acids C7:0 and C8:0 can give an early indication about the quality of used frying fats and oils.     

Glyceride composition of processed fats and oils as determined by glass capillary gas chromatography

Refined and bleached fats and oils can be analyzed directly by high-temperature glass capillary column gas chromatography after derivatization of the fatty acids, mono- and diglycerides with BSTFA [(N,O)-bis(trimethyl silyl) trifluoroacetamide]. The intact glycerides are separated on the basis of volatility to provide characteristic carbon number profiles (CNP). Quantitative information on mono-, di- and triglycerides, as well as free fatty acids, is obtained from a single, rapid separation. Profile values are reported for 13 different processed fats and oils. The analysis performed in the split-injection mode maintains column integrity after numerous separations, while producing acceptable relative standard deviations.     

光离子化气相色谱法对空气中挥发性有机物的测定研究

采用光离子化气相色谱仪新技术测定了室内空气中典型的挥发性有机化合物。研究了气相色谱仪柱温、载气压力对色谱峰的分辨率、保留时间和强度的影响,确定了光离子化气相色谱法测试苯系物的最佳条件,通过与传统FID气相色谱法的比对,结果表明:光离子化气相色谱法测定苯系物的灵敏度(检出限)比氢火焰离子化气相色谱法优于100倍以上,前者的分辨率也比后者的高。     

气相色谱法测定聚酯中二甘醇含量的研究

建立了氢火焰气相色谱测定聚酯(PET)中二甘醇(DEG)含量方法.利用PE色谱仪和Atlas色谱软件,采用内标法,通过准确度和精密度的考察来确定和验证最佳分析条件,同时探讨了中和剂PTA、冷却速度、样品尺寸大小、溶剂的挥发、进样量、进样速度及色谱仪与DEG含量准确度的相关性.     

Chemistry of archaeological animal fats

Animal fats are preserved at archaeological sites in association with unglazed pottery, human and animal remains, and other deposits or hoards. High-temperature gas chromatography (HT-GC) and combined HT-GC/mass spectrometry (HT-GC/MS) has confirmed the presence of animal fats in lipid extracts of artifacts. Degradation products and pathways have been discerned through the analyses of archaeological finds and the products of laboratory and field-based decay experiments. The origins of preserved fats have been determined through detailed compositional analysis of their component fatty acids by GC, by GC/MS of dimethyl disulfide derivatives of monoenoic components, and by GC-combustion-isotope ratio-MS (GC-C-IRMS), to derive diagenetically robust delta(13)C values. Regiospecific analysis of intact triacylglycerols by high-performance liquid chromatography/MS (HPLC/MS), with atmospheric pressure chemical ionization, provides a further criterion for establishing the origin of fats. Preparative GC has been employed to isolate individual fatty acids from archaeological pottery in sufficient amounts for (14)C dating.     

A rapid method for the determination oftrans unsaturation in fats and derivatives

Thetrans unsaturation present in samples of unsaturated fats and derivatives may be determined from measurement of the infrared absorbance at two wavelengths, one due totrans configuration of a double bond and the other due to the ester or acid group. The ratio of the two absorbance values has a linear relationship with thetrans unsaturation content. Thus, a drop of sample is diluted with CS₂ and the infrared absorbance measured at 10.36 μ and at 8.5–8.6 μ if esters and 10.7 μ if acids. To calculate the per cent isolatedtrans double bonds in the sample, the ratio of the two absorbance values is substituted into the linear equation which was developed from known samples. The method is rapid since the sample need not be weighed nor made up to a known volume and thus may be applied to samples such as those collected from a gas chromatograph or after thin layer chromatography. Presented at the AOCS Meeting, New York, October 1968.     

Analysis of disteryl ethers

Disteryl ethers isolated from a vegetable oil and a table margarine were analyzed by capillary gas chromatography. The composition of disteryl ethers in such products reveals whether vegetable oils are mixed with animal fats and if these materials have been subjected to in dustrial bleaching     

A COAL PYROLYSIS REACTOR SYSTEM WITH FAST ON-LINE COMPOSITION ANALYSIS BY GAS CHROMATOGRAPHY

The development of a coal pyrolysis reactor and a novel gas chromatography method for fast on-line composition analysis of pyrolysis products are presented. The annular fluidized bed reactor system minimizes particle agglomeration during the pyrolysis of plastic coals and the new column switching technique significantly reduces the time required for measuring the composition of low-volatile pyrolysis gases on a conventional gas chromatograph. Data from representative pyrolysis runs are presented and discussed.     

Gas-chromatographische Untersuchungen an Fetten tierischer Herkunft

Gas Chromatographic Investigation of the Fats of Animal Origin The C₁₄-, C₁₆- and C₁₈-fatty acid contents of a number of fats of animal origin were determined by gas chromatography. It could be shown in agreement with the results obtained by other authors that the fatty acid compositions of these fats are much more complicated than it was assumed just a few years ago. The gas chromatographic separation was carried out in such a manner that even the polyunsaturated fatty acids could be completely separated.     

Chromatographische Methoden bei der Untersuchung von Fritierfetten

Chromatographic Methods in the Investigations of Deep-Frying Fats 125 samples of deep-frying fats were investigated by various chromatographic methods (gaschromatography, gel permeation chromatography, column chromatography). The results were compared with the known criteria of alteration products (petroleum ether oxidised fatty acids (OXF). A content of 0.7% corresponded to 24.7% polar materials. The fraction of monomer glycerides was determined by gel permeation chromatography (GPC) on polystyrol-divinyl-copolymer (PL-Gel) which can be used at high pressure. However, gel permeation chromatography determines the sizes of the molecules and does not distinguish between non-oxidised and oxidised monomer glycerides in frying fats. Therefore the application of gaschromatography and GPC is proposed to calculate the part of non-oxidised monomer tri- and diglycerides. It was found that fat-samples with more than 0.7% oxidised fatty acids contained less than 86.7% monomer non-oxidised and oxidised di- and triglycerides and less than 71.6% monomer unaltered di- and triglycerides.     

Determination of the glyceride structure of fats

A method has been described for the quantitative determination of the following six glyceride types in fats: SSS, SSU, SUS, SUU, USU, and UUU. The method involved a quantitative oxidation of the unsaturated acids in the whole fat to the corresponding dicarboxylic acids. The oxidized fat was separated on a liquid-liquid partition column into two fractions, the first containing glycerides having no dicarboxylic acid or one dicarboxylic acid and the second containing glycerides with two or three dicarboxylic acids. Analysis of these fractions by gas chromatography coupled with lipase hydrolysis allowed the calculation of the proportions of the above six glyceride types. The oxidation, fractionation, lipase hydrolysis, gas chromatographic analysis, and the over-all method were checked on natural fats and mixtures of synthetic glycerides. The final glyceride composition appeared to be reliable to within plus or minus 2 unit per cent. Analyses are given for five natural fats. The compositions found agree very well with those calculated by a distribution theory recently proposed by Vander Wal. Contribution from the National Research Council of Canada, Prairie Regional laboratory, Saskatoon, Saskatchwan. Issued as N.R.C. No. 6161.