葵子油脂肪酸2-氨基-2-甲基-丙醇化学修饰气相色谱-质谱分析

以2-氨基-2-甲基-丙醇为脂肪酸的化学修饰试剂,气相色谱一电子轰击质谱（GC-EI MS）分析葵子油脂肪酸。2-氨基-2-甲基-丙醇将脂肪酸羧基修改为含氮杂环,使在EI源中避免了链烯基中碳碳双键的移动。解析了葵子油脂肪酸2-氨基-2-甲基-丙醇化学修饰产物的EI质谱图,讨沦了烯酸中碳碳双键的定位规则,确定了葵子油脂肪酸中碳碳双键的位置。鉴定出葵子油6种脂肪酸,不饱和脂肪酸相对含量为89．41％,其中人体必需脂肪酸9,12-十八碳二烯酸含量占65．30％。本方法为不饱和脂肪酸中双键的定位提供了新的技术手段。     

2-氨基-2-甲基丙醇化学修饰试剂用于气相色谱-质谱分析不饱和脂肪酸

以2-氨基-2-甲基丙醇为脂肪酸的化学修饰试剂,将不饱和脂肪酸羧基化学修饰成含氮杂环,从而避免了链烯基中碳碳双键在EI源中的移动,并使质谱呈现显示双键位置的规范信息。通过解析不饱和脂肪酸2-氨基-2-甲基丙醇化学修饰产物的EI质谱图,得到了不饱和脂肪酸中碳碳双键的定位规则,从而为分析不饱和脂肪酸精细结构提供了手段。用脂肪酸2-氨基-2-甲基丙醇化学修饰气相色谱-EI质谱法分析了螺旋藻脂肪酸,鉴定出9种不饱和脂肪酸,确定了螺旋藻脂肪酸中碳碳双键的位置,结果与文献一致。     

液相色谱/质谱大气压化学电离源鉴定深海鱼油中长链不饱和脂肪酸

以1,2-苯并-3,4-二氢咔唑-9-乙基苯磺酸酯为衍生化试剂,在充氮的气氛下对鱼油进行皂化处理,所得皂化产物经正己烷萃取处理后进行柱前衍生化,再以HPLC/MS分离和鉴定。通过对长链脂肪酸分子的标记处理,其衍生物分子在质谱分析中呈现出双键位置的规范信息。通过建立模型计算式,借助不饱和脂肪酸的分子离子峰和特征碎片离子峰的质量数,计算不饱和的碳碳双键位置。共鉴定出23种脂肪酸。结果表明深海鱼油主要由C12-C22的脂肪酸组成,多不饱和脂肪酸含量占67.08%(峰面积百分比,下同),其中C16∶19-十六碳烯酸(11.7%);C16∶44,7,10,13-十六碳四烯酸(2.91%);C18∶112-十八碳烯酸(11.1%);C18∶46,9,12,15-十八碳四烯酸(3.62%);C20∶113-二十碳烯酸(1.21%);C20∶55,8,11,14,17-二十碳五烯酸(16.71%);C22∶62,5,8,11,14,17-二十二碳六烯酸(10.53%)。所建立的方法为不饱和脂肪酸碳链中双键位置的确定提供了新的技术手段。     

L-苏式二氢鞘氨醇的立体选择性合成

二氢鞘氨醇（ＤＨＳ）是２－氨基－１，３－二羟基的饱和长链氨基醇化合物，是构成鞘脂类（包括鞘磷脂和糖鞘脂）的主链部分．由于鞘脂类在自然界中来源稀少，又很难得到纯品．因此，作为鞘脂类主链部分的二氢鞘氨醇的合成有重要的意义［１］．二氢鞘氨醇有两个手性碳，共...     

鱼油中的长链脂肪酸分析

我国渔产丰富,鱼油中含有大量的脂肪酸,其中很多是长链不饱和脂肪酸,近年来有人利用鱼油作为降胆固醇的药物,也有人利用不饱和脂肪酸合成具有生物活性的前列腺素。为充分了解并更好地利用我国的鱼油资源,我们用毛细管色谱-质谱(电子轰击电离/化学电离)方法分析了一种海鱼——马面屯鱼的鱼油,并与一种淡水鱼——花鲢鱼的鱼油作了比较。虽然鱼油的分析近年来国外有很多报道,但尚未见到利用 GC/MS 来分析马面屯鱼油中脂肪酸成分的。两种鱼油分析结果对比后证实了马面屯鱼油中具有较多的长碳链不饱和脂肪酸,临床价值应高于花鲢鱼。     

气相色谱/质谱法分析孔石莼中的脂肪酸

建立了孔石莼脂肪酸的气相色谱/质谱(GC/MS)测定方法。使用Folch法提取了孔石莼中的总脂,经过2 mol/L HCl-甲醇溶液的甲酯化处理后,采用GC/MS法对其脂肪酸组成进行了分离分析,同时结合有机质谱学规律,分别对饱和脂肪酸甲酯、单不饱和脂肪酸甲酯和多不饱和脂肪酸甲酯的裂解规律和质谱特征进行了分析归纳。通过质谱数据库检索和标准品对照,鉴定出孔石莼中的24种脂肪酸,其中9,12,15-十八碳三烯酸、4,7,10,13-十六碳四烯酸和6,9,2,15-十八碳四烯酸3种主要多不饱和脂肪酸占总脂肪酸含量的45.14%。通过对孔石莼中脂肪酸的分析,表明特征离子在脂肪酸甲酯尤其是多不饱和脂肪酸甲酯的定性方面具有很好的应用价值。     

超高效液相色谱-四极杆串联飞行时间质谱分析黄酮类化合物及小毛茛茎叶的成分

为了探索液相色谱-质谱联用(LC-MS)技术在快速识别中药及天然产物成分中的应用,以黄酮对照品为研究前体,药用植物小毛茛为研究对象,采用超高效液相色谱/二极管阵列检测器-电喷雾四极杆串联飞行时间质谱(UPLC/DAD-ESI/Q-TOF MS)分析了黄酮类化合物同系物及同分异构体的色谱、质谱特性。结果显示:黄酮氧苷和黄酮碳苷的紫外吸收光谱及二级质谱具有显著性差异,糖苷化位置同保留时间、二级质谱碎片及相对丰度具有相关性。将该方法应用于小毛茛茎叶醇提液的分析,结合其酸水解液的分析,解析了22个黄酮醇糖苷和3个苷元。方法简便,具有可操作性。     

景洪哥纳香和大叶紫玉盘化学成分研究

从景洪哥纳香和大叶紫玉盘根醇提物中，采用色谱分离方法，分别得到43个和 33个化合物，通过波谱技术和化学方法鉴定了这些化合物的结构。其中，从景洪哥 纳香根中得到1个新化合物，命名为8－乙酰基－9－去氧哥纳香吡喃吡喃酮（1）； 从大叶紫玉盘根中得到1个新化合物，命名为大叶素A（2）。另外，从景洪哥纳香 根中，还分离得到一个神经鞘胺醇苷成分混合物asteriacerebrosides (3)，并通 过GC－MS技术，鉴定了该混合物的脂肪酸部分（FAM）和长链胺部分（LCB）的种类 数目及碳链长度。结果表明，3中脂肪酸部分，含7个脂肪酸，碳链长度分别是16, 18, 19, 20, 21, 22和23个碳；其长链胺部分包含5个脂肪胺，对应链长度为21， 22，23，24和25个碳。     

生物柴油树种油脂脂肪酸组成对燃料特性的影响

以目前中国主要开发或具有开发潜能的10种生物柴油树种为研究对象,分析其果实或种子油脂脂肪酸组成对合成生物柴油燃料特性的影响。结果表明,木本植物生物柴油产品十六烷值、碘值、氧化安定性等燃料特性主要由原料油脂肪酸的不饱和度决定,脂肪酸不饱和度低于133.13,十六烷值(GB/T 20828-2007)和碘值(EN 14214)就可以达标。生物柴油产品冷滤点随着长碳链饱和脂肪酸的增加而升高,脂肪酸饱和碳链长度因子分别小于8.41和2.72时,可以满足冷滤点0℃和-10℃的要求。高品质生物柴油的原料中应该具有较高的单元不饱和脂肪酸含量。通过油脂脂肪酸单不饱和脂肪酸、多不饱和脂肪酸和饱和脂肪酸的组成绘制出生物柴油特性三角预测图,为预测生物柴油产品燃料特性提供参考依据。     

超高效液相色谱-四极杆-飞行时间质谱法快速筛查辣椒粉中27种农药残留

建立了超高效液相色谱-四极杆-飞行时间质谱（UPLC-Q-TOF/MS）快速筛查辣椒粉中27种农药残留的检测方法。样品采用乙腈提取,经Carb/NH₂固相萃取小柱净化,用乙腈-乙酸乙酯（3：1,v/v）洗脱,电喷雾正离子模式检测。在一级质谱模式下,以目标物的保留时间、精确质量数、同位素分布和同位素丰度比定性,以准分子离子峰的峰面积定量。在Targeted MS/MS模式下,通过相应碰撞能量下的离子碎片信息进一步确证。27种化合物在各自的线性范围内线性关系良好,相关系数均大于0.997。27种化合物的定量限为2.5~5.0 μg/kg,在3个添加水平下的回收率为72.3%~118.9%,相对标准偏差（RSD）为0.21%~12.7%（n=6）。该方法快速、灵敏、准确,适用于辣椒粉中多种农药残留的同时检测。     

Determination of free fatty acids in chocolate by liquid chromatography with tandem mass spectrometry

This paper describes a rapid extraction method, based on a matrix solid-phase dispersion technique using diatomaceous earth as solid support and 50:50 (v/v) chloroform/methanol as extracting solvent, that can determine 11 free fatty acids in chocolate. The extraction procedure is followed by reversed-phase liquid chromatography/tandem mass spectrometry (LC/MS/MS) using a normal-bore (4.6 mm i.d.) C-18 column and an electrospray interface operating in the negative ion mode. The tandem mass spectra of selected compounds show that charge-remote fragmentation (CRF) mechanisms are occurring; the intensities of the CRF reactions increase with the carbon number and degree of unsaturation of the fatty acids. Average recoveries, evaluated by the standard addition method, vary between 79-103%, and the estimated quantification limits are less than 153 ng/g. The proposed method has been used to analyse nine chocolate samples from various price ranges, bought from supermarkets.     

液相色谱-电喷雾质谱法分析脂肪醇聚氧乙烯醚硫酸钠

采用电喷雾质谱(ESI/MS)技术建立了脂肪醇聚氧乙烯醚硫酸钠(AES)的烷基碳链分布、乙氧基分布及平均EO数、平均相对分子质量的测定方法;采用液相色谱-电喷雾质谱(LC-ESI/MS)测定了AES中的游离十二烷基硫酸钠(SDS)的含量。将本方法应用于实际样品的测定,并与核磁共振法测得的平均EO数进行比较,二者的测定结果相当吻合,从而验证了本法的可靠性。     

Analysis of triglycerides in food items by desorption electrospray ionization mass spectrometry

The triglyceride composition and oxidation behavior of edible oil and margarine samples were analyzed by desorption electrospray ionization mass spectrometry (DESI‐MS). For the characterization of the lipids, the chain length and the degree of unsaturation of the fatty acids were determined. The measurements were carried out in positive ion mode; the triglycerides were detected as alkali metal or ammonium adducts. The DESI solvent was water/methanol 1:1 (v/v); measurements were carried out both with and without the addition, as an ionizing agent, of ammonium acetate that enhances the signal intensity of the ammonium adduct ions. The spectra were interpreted for both cases and intensities were compared. Triglyceride monomers and dimers were observed in the spectra. Tandem mass spectrometric (MS/MS) measurements were carried out to determine the structure of the triglycerides. It was demonstrated that the terminal fatty acids in the sn1‐ or sn3‐position are more likely to be cleaved than the internal fatty acid (sn2‐position). Characteristic triglyceride patterns were obtained using a simple and rapid sample preparation protocol comprising the simple deposition of samples onto a glass carrier surface. The triglyceride data was analyzed by principal component analysis (PCA). The different edible oils were clearly separated and the hydrogenated derivatives were identified by their triglyceride spectra. The oxidation of the oil samples was observed and the oxidation products were detected and identified. This method provides a fast and simple technique for the detection and analysis of triglycerides in oil‐ or fat‐containing samples ranging from food items to tissue samples. The potential application areas include nutritional studies, the food industry and cosmetics. Copyright © 2010 John Wiley & Sons, Ltd.     

Positional isomer differentiation of synthetic cannabinoid JWH‐081 by GC‐MS/MS

Like many new designer drugs of abuse, synthetic cannabinoids (SC) have structural or positional isomers which may or may not all be regulated under law. Differences in acute toxicity may exist between isomers which impose further burden in the fields of forensic toxicology, medicine and legislation. Isomer differentiation therefore becomes crucial from these standpoints as new designer drugs continuously emerge with just minor positional modifications to their preexisting analogs. The aim of this study was to differentiate the positional isomers of JWH‐081. Purchased standard compounds of JWH‐081 and its positional isomers were analyzed by gas chromatography‐electron ionization‐mass spectrometry (GC‐EI‐MS) first in scan mode to investigate those isomers who could be differentiated by EI scan spectra. Isomers with identical or near‐identical EI spectra were further subjected to GC‐tandem mass spectrometry (MS/MS) analysis with appropriate precursor ions. EI scan was able to distinguish 3 of the 7 isomers: 2‐methoxy, 7‐methoxy and 8‐methoxy. The remaining isomers exhibited near‐identical spectra; hence, MS/MS was performed by selecting m/z 185 and 157 as precursor ions. 3‐Methoxy and 5‐methoxy isomers produced characteristic product ions that enabled the differentiation between them. Product ion spectrum of 6‐methoxy isomer resembled that of JWH‐081; however, the relative ion intensities were clearly different from one another. The combination of EI scan and MS/MS allowed for the regioisomeric differentiation of the targeted compounds in this study. Copyright © 2015 John Wiley & Sons, Ltd.     

Liquid chromatography with dual parallel mass spectrometry and 31P nuclear magnetic resonance spectroscopy for analysis of sphingomyelin and dihydrosphingomyelin. II. Bovine milk sphingolipids

Liquid chromatography coupled to atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) mass spectrometry (MS), in parallel, was used for simultaneous detection of bovine milk sphingolipids (BMS). APCI-MS mass spectra exhibited mostly ceramide-like fragment ions, [Cer-H(2)O+H](+) and [Cer-2H(2)O+H](+), which were used to identify individual molecular species of BMS according to fatty acyl chain length:degree of unsaturation and long-chain base (LCB). ESI-MS was used to confirm the molecular weights of BMS species. Both sphingomyelin (SM) and dihydrosphingomyelin (DSM) molecular species were identified, with DSM species constituting 20% of BMS. Approximately 56 to 58% of DSM species contained a d16:0 LCB, while 34 to 37% contained a d18:0 LCB. Approximately 26 to 30% of SM species contained a d16:1 LCB, while 57 to 60% contained a d18:1 LCB. BMS species contained both odd and even carbon chain lengths. The most abundant DSM species contained a d16:0 LCB with a 22:0, 23:0 or 24:0 fatty acyl chain, while the most abundant SM species contained a d18:1 LCB with a 16:0 or 23:0 fatty acyl chain. (31)P NMR spectroscopy was used to conclusively confirm that DSM is a dietary component in BMS.     

GC／MS检测信息的综合利用

从充分利用气相色谱／质谱（ＧＣ／ＭＳ）提供的信息来鉴定ＧＣ流出组分的目的出发，并以脂肪醇分析为例讨论了ＧＣ保留指数在ＭＳ谱图解析及ＭＳ鉴定结果的合理性检验方面的作用。总结了ＧＣ保留的同系物规律、极性规律、加和规律及异构物规律来指导ＭＳ谱图解析。提出了含氧化合物官能团相对于－ＣＨ２－质量数的保留指数附加贡献值辅助ＭＳ确定化合物的类别。同时采用了ＧＣ／ＭＳ中选择离子检测方法（ＳＩＭ）在分子离子峰受噪音干扰或太弱以至完全未观测到时来进一步佐证其相对分子质量。     

An isomer-specific high-energy collision-induced dissociation MS/MS database for forensic applications: a proof-of-concept on chemical warfare agent markers

Spectra database search has become the most popular technique for the identification of unknown chemicals, minimizing the need for authentic reference chemicals. In the present study, an isomer‐specific high‐energy collision‐induced dissociation (CID) MS/MS spectra database of 12 isomeric O‐hexyl methylphosphonic acids (degradation markers of nerve agents) was created. Phosphonate anions were produced by the electrospray ionization of phosphonic acids or negative‐ion chemical ionization of their fluorinated derivatives and were analysed in a hybrid magnetic‐sector–time‐of‐flight tandem mass spectrometer. A centre‐of‐mass energy (E_com) of 65 eV led to an optimal sequential carbon–carbon bond breakage, which was interpreted in terms of charge remote fragmentation. The proposed mechanism is discussed in comparison with the routinely used low‐energy CID MS/MS. Even‐mass (odd‐electron) charge remote fragmentation ion series were diagnostic of the O‐alkyl chain structure and can be used to interpret unknown spectra. Together with the odd‐mass ion series, they formed highly reproducible, isomer‐specific spectra that gave significantly higher database matches and probability factors (by 1.5 times) than did the EI MS spectra of the trimethylsilyl derivatives of the same isomers. In addition, ionization by negative‐ion chemical ionization and electrospray ionization resulted in similar spectra, which further highlights the general potential of the high‐energy CID MS/MS technique. Copyright © 2011 John Wiley & Sons, Ltd.     

液相色谱-四极杆飞行时间质谱法快速筛查与确证中华鳖中未知着色剂

建立了液相色谱-四极杆飞行时间质谱(LC-Q-TOF MS)对中华鳖中未知着色剂的快速筛查方法。20个中华鳖样品经过简易的乙腈提取净化后,利用液相色谱-二极管阵列检测器(LC-DAD)对未知着色剂进行定位。选定其中响应最强的样品S7,同时在线获取其在不同洗脱程序下未知着色剂定位时间段的质谱信息,经阴性样品扣除本底后匹配获得一对精确质量数差异在5 mDa以内的特征提取离子(分别为564.39773 Da和564.39561 Da)。通过质谱定性分析处理软件对上述特征提取离子对进行分子式生成,确认两者分子式为C₄₀H₅₂O₂,推测其同为未知着色剂。结合该未知着色剂的紫外-可见光谱信息与文献资料,推断该化合物可能为角黄素。通过角黄素标准品建立的飞行时间质谱"二级确证谱库"对样品中未知着色剂进行进一步的匹配确证,最终确证其为角黄素。本研究讨论了基于LC-Q-TOF MS方法的化合物筛查策略,实验表明其可快速对中华鳖中的未知着色剂进行筛查和确证。     

Identification of linoleic acid free radicals and other breakdown products using spin trapping with liquid chromatography-electrospray tandem mass spectrometry

Linoleic acid radical products formed by radical reaction (Fenton conditions) were trapped using 5,5-dimethyl-1-pyrrolidine-N-oxide (DMPO) and analysed by reversed-phase liquid chromatography coupled to electrospray mass spectrometry (LC-MS). The linoleic acid radical species detected as DMPO spin adducts comprised oxidized linoleic acid and short-chain radical species that resulted from the breakdown of carbon and oxygen centred radicals. Based on the m/z values, the short-chain products were identified as alkyl and carboxylic acid DMPO radical adducts that exhibited different elution times. The ions identified as DMPO radical adducts were studied by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The LC-MS/MS spectra of linoleic acid DMPO radical adducts exhibited the fragment ion at m/z 114 and/or the loss of neutral molecule of 113 Da (DMPO) or 131 Da (DMPO + H2O), indicated to be DMPO adducts. The short-chain products identified allowed inference of the radical oxidation along the linoleic acid chain by abstraction of hydrogen atoms in carbon atoms ranging from C-8 to C-14. Other ions containing the fragment ion at m/z 114 in the LC-MS/MS spectra were attributed to DMPO adducts of unsaturated aldehydes, hydroxy-aldehydes and oxocarboxylic acids. The identification of aldehydic products formed by radical oxidation of linoleic acid peroxidation products, as short-chain product DMPO adducts, is a means of identifying lipid peroxidation products.     

Biopolymer sequencing using a triple quadrupole mass spectrometer in the ESI nozzle-skimmer/precursor ion MS/MS mode

A variety of model biopolymers, including oligonucleotides, oligosaccharides and a synthetic pharmaceutical agent, were sequenced using a triple quadrupole mass spectrometer equipped with an electrospray source and operated in a scan mode referred to as pseudo-MS3. This scan mode consists of three steps: (1) in-source collision-induced dissociation (CID) in the nozzle-skimmer (NS) region, (2) scanning of the fragment ions into the collision cell for further CID, and (3) passing of the secondary fragment ions through the final mass filter at a preselected mass, generally corresponding to the mass of a terminal sequence ion for the biopolymer. The mass spectra are recorded in the precursor ion MS/MS mode where ion selection and detection occur at the third stage of the triple quadrupole but the scan function is determined by the first stage. The advantages and limitations in using this pseudo-MS3 NS/precursor ion MS/MS scan mode for biopolymer sequencing are discussed.