气质联用技术分析黑枸杞中脂肪酸组成

目的:为了研究黑枸杞的营养功能。方法:通过甲酯化反应,以正己烷为溶剂直接进样,由气相色谱—质谱联用仪分析了黑枸杞中的脂肪酸化合物成分。结果:黑枸杞中的不饱和脂肪酸接近80%,具有良好的保健价值和药用价值。结论:研究结果可为今后黑枸杞的脂肪酸化学成分研究及其它营养功能开发提供理论依据。     

气质联用技术在发酵食品风味分析中的研究进展

发酵食品是一类有着独特风味的食品。气质联用技术是目前较为成熟的用以分析和检测化合物常用的分析方法之一,可用于对发酵食品的风味进行分析。研究了气质联用技术与多种预处理方法相结合的方式,以及气质连用技术在发酵食品的风味分析中的应用,发现气质联用技术在检测发酵食品的风味成分方面较快速,鉴别物质的能力强,效果明显,分析的结果准确。可为分析鉴定发酵食品中关键风味物质提供参考。     

樱桃仁的脂肪酸组成与含量分析

用气相色谱-质谱联用(GC-MS)测定樱桃仁中的脂肪酸含量,用外标法与峰面积归一法两种方法进行定量分析。樱桃仁以不饱和脂肪酸为主,樱桃仁中单不饱和脂肪酸36.24%,多不饱和脂肪酸44.04%。樱桃仁中四种脂肪酸含量:亚油酸油酸棕榈酸硬脂酸。     

柚子籽的脂肪酸组成与含量分析

通过气相色谱-质谱联用(GC-MS)测定柚子籽中的脂肪酸含量,用外标法与峰面积归一法两种方法,进行对比定量分析。柚子籽脂肪酸种类丰富,以不饱和脂肪酸为主,柚子籽中不饱和脂肪酸为67.42%。柚子籽中4种脂肪酸含量:亚油酸棕榈酸油酸硬脂酸。     

荞麦籽油的脂肪酸组成与含量分析

通过气相色谱-质谱联用(GC-MS)测定荞麦籽油中的脂肪酸含量,用外标法与峰面积归一法进行定量分析。荞麦籽油脂肪酸种类丰富,以不饱和脂肪酸为主,其中单不饱和脂肪酸为45.10%,多不饱和脂肪酸为32.76%。荞麦籽油中4种脂肪酸含量:油酸亚油酸棕榈酸硬脂酸。     

气质联用检测技术在食品安全卫生检验中的应用研究

气相色谱法基于其分析效率高、选择性好、灵敏度高、分离性能好等优点在化学分析和食品分析领域得到广泛的应用.虽然气相色谱的优点众多,但是对未知化合物的分析鉴定却不如质谱法,将二者进行联用后,除了可用于分析一般的有机物以外,还可分离检测复杂的化合物.该方法被众多研究者们用于食品安全卫生检测中,本文综述了气质联用检测技术近几年...     

GC-MS外标法分析核桃仁中的脂肪酸含量

利用气相色谱-质谱联用(GC-MS)的外标法对核桃仁中的脂肪酸进行定量分析。核桃仁脂肪酸种类丰富,常见的4种脂肪酸在核桃仁中的含量:亚油酸油酸棕榈酸硬脂酸。相对标准偏差RSD(n=5)在2.27%~11.98%之间,样品回收率测定在81.0%~109.0%之间。     

气相色谱质谱联用仪测定芝麻油中脂肪酸组成的方法研究

利用气相色谱质谱联用仪测定芝麻油脂肪酸组成,采用三种溶剂(正己烷、正庚烷、异辛烷)提取芝麻油,用甲醇钠-甲醇(27克/升)甲酯化,结果显示采用异辛烷提取芝麻油脂肪酸成分非常稳定,保留时间RSD在0. 005～0. 009%,峰面积RSD在1. 28～1. 46%,浓度RSD在1. 28～1. 47%,同时采用HP-88气相色谱柱,建立Q3-SIM的方法,研究了37种脂肪酸组成三重四级杆气质联用仪的测定,结果显示37种脂肪酸的检出限在0. 25～1. 0mg/L,定量限在0. 75～3. 0mg/L,线性关系良好,相关系数均在0. 999以上,用母离子定量,子离子定性,离子比率均在30%以内,从而可以更加准确地定量和定性脂肪酸组成,优于气相色谱仪的定量和定性,减少假阳性的发生。     

海洛因的气质联用分析

采用气质联用 (GC/MS)方法 ,对海洛因样品进行了检测分析 ,结果检出了海洛因、单乙酰吗啡、乙酰可待因、茶碱、咖啡因及巴比妥等成分 ,其中海洛因工作曲线的线性方程为A =2 4 4 86 .5×C +45 15 7.2 ,相关系数r=0 9987,海洛因含量为 7 5 3%。     

气质联用色谱测定江西产地桉叶油成分

为了分析江西产地桉叶油的化学成分,采用气相色谱-质谱联用仪(GC-MS)对江西产地的5批次桉叶油进行成分鉴定.结果表明,经GC-MS分析鉴定出桉叶油含29种成分,江西产地桉叶油主要成分桉油精含量为:22.31％、22.50％、22.49％、22.41％和22.44％.     

Characterization of fatty acid isomers in dehydrated castor oil by gas chromatography and gas chromatography-mass spectrometry techniques

Fatty acid isomers present in dehydrated castor oil were analyzed by gas chromatography and gas chromatography-mass spectrometry (GC-MS) of their dimethyl oxazoline derivatives. Conjugated linoleic acid 9,11 and 10,12 isomers were identified by GC based on equivalent chainlengths. Segmental peak analysis of GC-MS total ion chromatogram mass fragmentation pattern revealed the presence of 7,9 and 8,10 conjugated linoleic acids along with 9,11 and 10,12 conjugated linoleic acids. Interestingly, a reverse elution of trans,trans-conjugated linoleic acids was observed, viz. 10,12 was followed by 9,11, which was in turn followed by the 8,10 and 7,9 isomers. The observed reverse order of elution was in contrast to the conventional elution pattern of both nonconjugated and conjugated cis,cis-, cis,trans- and trans,cis-isomers.     

Analysis of autoxidized fats by gas chromatography-mass spectrometry: I. Methyl oleate

A structural investigation of autoxidation products of methyl oleate was carried out by gas chromatography-mass spectrometry (GC-MS) of trimethylsilyl (TMS) ether derivatives. GC-MS using computer plots of selected masses afforded structural assignments of GC peaks due to incompletely resolved mixtures. This method provided evidence of epoxy and keto esters which are not completely separated from the main components consisting of the TMS derivatives of the allylic hydroxy esters. Use of an MS-computer system also showed that the hydroxyoctadecanoate TMS ethers were partially separated by GC. The use of synthetic hydroxyoctadecanoates for the first time enabled us to demonstrate the quantitative reliability of a GC-MS computer summation approach to analyze the isomeric composition of oleate hydroperoxides (as the saturated TMS ether derivatives). Consistently higher concentrations were found of the 8- and 11-hydroperoxides than of the 9- and 10-hydroperoxides. Minor products of autoxidation identified by GC-MS include allylic enones, isomeric epoxyoctadecanoates, dihydroxyctadecenoates, and dihydroxyoctadecanoates. Presented at the AOCS Meeting, Chicago, September 1976.     

Analysis of autoxidized fats by gas chromatography-mass spectrometry: II. Methyl linoleate

The gas chromatography-mass spectrometry (GC-MS) approach developed in the preceding paper was applied for qualitative and quantitative investigations of autoxidation products of methyl linoleate. A GC-MS computer summation method was standardized with synthetic 9- and 13-hydroxyoctadecanoate. Equal amounts of 9- and 13-hydroperoxides were found in all samples of linoleate autoxidized at different temperatures and peroxide levels. The results are consistent with the classical free radical mechanism of autoxidation involving a pentadiene intermediate having equivalent sites for oxygen attack at carbon-9 and carbon-13. Minor oxygenated products of autoxidation indicated by GC-MS include keto dienes, epoxyhydroxy monoenes di- and tri-hydroxy monoenes. These hydroxy compounds are presumed to be present in the form of hydroperoxides. The quantitative GC-MS method was found suitable for the analysis of autoxidized mixtures of oleate and linoleate. By this method, it is possible to determine the origin of the hydroperoxides formed in mixtures of these fatty esters. Presented at the AOCS Meeting, Chicago, September 1976.     

Analysis of autoxidized fats by gas chromatography-mass spectrometry: III. Methyl linolenate

The gas chromatography-mass spectrometry (GC-MS) method developed in the preceding papers was extended to the analysis of autoxidation products of methyl linolenate. Four isomeric hydroxy allylic trienes with a conjugated diene system were identified after reduction of the linolenate hydroperoxides. All eight geometrictrans,cis- andtrans, trans-conjugated diene isomers of these hydroxy allylic compounds were identified and partially separated by GC of the trimethylsilyl (TMS) ether derivatives. The proportion found of 9- and 16-hydroperoxides was significantly higher (75–81%) than the 12- and 13-hydroperoxides (18–25%). The tendency of the 12- and 13-hydroperoxides to form cyclic peroxides, cyclic peroxidehydroperoxides, and prostaglandin-like endoperoxides was supported by indirect evidence for the presence of 9,10,12- and 13,15,16-trihydroxyoctadecanoate in hydrogenated derivatives of the highly oxygenated products. The quantitative GC-MS method was used to determine the relative contribution of linolenate, linoleate, and oleate in mixtures to the formation of hydroperoxides. Presented at the AOCS Meeting, New York, May 1977.     

Analysis of autoxidized fats by gas chromatography-mass spectrometry: V. Photosensitized oxidation

The role of singlet oxygen in oxidation was studied by analyzing hydroperoxide isomers in unsaturated fats and esters by gas chromatography-mass spectrometry (GC-MS). On oxidation photosensitized with methylene blue at 0 C, methyl oleate produced a 50–50% mixture of 9- and 10-hydroperoxides, linoleate a mixture of 66% conjugated (9+13) and 34% unconjugated (10+12) hydroperoxides, and linolenate a mixture of 75% conjugated (9+12+13+16) and 25% unconjugated (10+15) hydroperoxides. Cottonseed, safflower, and corn oil esters showed, as in soybean esters, the presence of varying amounts of 12-hydroxy esters derived from the corresponding hydroperoxide at low peroxide values. Since these oils do not contain linolenic acid, a likely source of the 12-hydroperoxide is linoleic acid by photosensitized oxidation. Several lines of evidence support the conclusion that singlet oxygen may contribute to the unique hydroperoxide composition of vegetable oil esters at low levels of oxidation. In the presence of photosensitizers such as methylene blue and chlorophyll, the unique hydroperoxide composition (high levels of 10- and 12-hydroperoxides) obtained in soybean esters was similar to that produced by oxidation at low peroxide values. In contrast, a normal hydroperoxide composition was produced, as expected from the fatty acid composition of soybean oil esters, when singlet oxygen quenchers such as β-carotene and α-tocopherol were used and when the esters were treated with carbon black to remove natural photosensitizers. GC-MS analyses of the derived unsaturated alcohols provided indirect evidence for 12-hydroperoxy-9,13-diene in soybean esters as expected by photosensitized oxidation of linoleate. Presented at the AOCS Meeting, San Francisco, California, April 29–May 3, 1979. 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.     

Combination gas chromatography-mass spectrometry

The direct combination of gas-liquid chromatography with mass spectrometry represents one of the most powerful techniques available for the analysis of complex mixtures of lipids. Principal advantages are the extremely small amounts of material required, the relative speed of analysis, and the wealth of molecular structural information available. The ability to record rapidly several mass spectra of one emerging chromatographic peak may also frequently be of use in detecting impurities, unresolved mixtures, or thermal decomposition of the sample. In the development of new gas chromatographic analytical procedures, the combination instrument may frequently prove highly useful for following chemical reactions in the preparation of new types of derivatives for GLC.     

Characterization of branched-chain fatty acids from fallow deer perinephric triacylglycerols by gas chromatography-mass spectrometry

Branched-chain fatty acids of perinephric triacylglycerols of semi-feral fallow deer (Dama dama dama) were analyzed by high resolution gas chromatography-mass spectrometry. Of the total fatty acids, 15.50% were Branched-chain components including 8.96% iso acids, mostly 14-methylpentacanoic acid, 2.85% anteiso acids and 1.73% of other monomethyl-substituted acids; dimethyl-branched acids with an iso structure (1.05%) and with an anteiso structure (0.18%) were also present. Whereas the predominant iso acids and methyl-substituted iso acids had chain lengths of 13 and 15 carbon atoms, the anteiso acids and methyl-substituted anteiso acids had chain lengths of 14 and 16 carbon atoms. Methyl substitution occurred on the even numbered carbon atoms relative to the carboxyl group. The general composition is also given of the fatty acids comprising the triacylglycerols of subcutaneous (rump area) and perinephric adipose tissue.     

Analysis of autoxidized fats by gas chromatography-mass spectrometry. IV. Soybean oil methyl esters

An unusual isomeric distribution of hydroperoxides has been found in soybean oil esters oxidized at low levels (peroxide values below 50). The unexpectedly high concentration of the 12-hydroperoxide isomer is in marked contrast to the isomeric composition of oxidized pure linolenate. The different isomeric hydroperoxides observed at low levels of oxidation may contribute through their decomposition to the unique flavor deterioration of soybean oil. Quantitative gas chromatographymass spectrometry (GC-MS) used in this study provides for the first time an answer to the basic question of which hydroperoxides contribute to the state of oxidation of soybean oil. Results of GC-MS were confirmed by capillary gas chromatography. Analyses of highly oxidized soybean esters (peroxide values 468 and 2352) reveal the same main compounds as those found in oxidized pure linoleate, together with small amounts of oleate and linolenate hydroperoxides. Presented at AOCS Meeting, St. Louis, Missouri, May 14–18, 1978. 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.     

Determining double-bond positions in monoenoic 2-hydroxy fatty acids of glucosylceramides by gas chromatography-mass spectrometry

We applied a gas chromatography-mass spectrometry (GC-MS) method using dimethyl disulfide (DMDS) adducts and were able to determine the double-bond positions in monounsaturated 2-hydroxy fatty acids (2-HFA). 2-HFA methyl esters, prepared from the hydrolysate ofArabidopsis thaliana leaf glucosylceramides, were acetylated and methylthiolated. GC-MS analysis of the resulting DMDS adducts showed simple mass spectra with recognizable molecular ions and a series of key fragment ions indicating the original double-bond positions in the aliphatic chain. Based on this GC-MS elucidation, we confirmed thatArabidopsis leaf glucosylceramides have C₂₂, C₂₃, C₂₄, C₂₅, and C₂₆ chain length 2-HFA with monounsaturation, and all their double bonds are placed at the n−9 position. This procedure is simple, time efficient, and highly sensitive.