超高效液相色谱-串联四极杆飞行时间高分辨质谱用于太平洋鳕鱼脂质轮廓分析

建立了超高效液相色谱-串联四极杆飞行时间高分辨质谱(UPLC-Triple TOF-MS/MS)分析脂质轮廓的方法。色谱柱选用ACQUITY UPLC CSH C₁₈柱(150 mm×2.1 mm, 1.7μm),流动相A为乙腈-水(65∶35,V/V),流动相B为异丙醇-乙腈(85∶15,V/V),两者均含5 mmol/L甲酸铵和0.1%甲酸;质谱采用IDA自动二级扫描模式。13类脂质标准品在一定浓度范围内具有良好的线性关系,线性相关系数(R²)均大于0.995,检出限(LOD)为0.001～0.25μmol/L,定量限(LOQ)为0.0025～0.2μmol/L,相对标准偏差(RSD)均小于10%,大部分标准品的回收率大于80%。采用氯仿-甲醇(2∶1,V/V)提取太平洋鳕鱼肌肉组织中的脂质,共鉴定出498个脂质分子种类,包括255个磷脂、52个鞘脂、191个甘油酯,主要亚类分别为磷脂酰乙醇胺、鞘磷脂、甘油二酯。本方法具有高灵敏、高分辨和高通量等优点,可用于太平洋鳕鱼脂质轮廓的分析,为脂质组学在水产品领域中的应用奠定了方法学基础。     

液相色谱-电喷雾离子阱串联质谱分析烟草水提取物中的尼古丁

用液相色谱-电喷雾线性离子阱串联/质谱(LC-ESI-ITMS/MS)在正离子模式下对烟草水提取物中的尼古丁进行了分析:定性分析了尼古丁MS/MS图谱中碎片的可能结构;用尼古丁标准溶液对质谱检测条件进行优化后,在SRM扫描模式下对尼古丁进行定量分析。最低检出限(LOD)可达0.21μg/L;回收率为99%-105%。测试3个不同浓度样品得到的RSD为0.64%-0.72%。实验选用高效的短色谱柱达到了快速定量的目的,适用于对大量样品的分析。     

超高效液相色谱-飞行时间-串联质谱法用于大白菜叶片中的脂质成分分析

建立了超高效液相色谱-飞行时间-串联质谱(UPLC-TOF-MS/MS)分析大白菜叶片中脂质的种类、结构、脂肪酸组成并检测其相对含量的方法。以Acquity UPLCTMBEH C8色谱柱为固定相,采用飞行时间质谱全扫描-信息关联采集-子离子扫描(TOF-MS scan-IDA-product ion scan)复合模式实现一次进样分析,同时获得脂质的一级和二级质谱信息。在大白菜叶片中共鉴定得到232种脂质,包含104种磷脂、63种糖脂和65种甘油酯。其中,磷脂、糖脂和甘油酯中的主要成分分别为磷脂酰胆碱、单半乳糖二酰甘油和甘油二酯、甘油三酯。结果表明,该方法具有灵敏度高、准确度高和高通量等优点,为植物脂质的代谢研究提供了可靠的分析技术平台,并为进一步的脂质生物学功能研究奠定了基础。     

2-氨基-3-硝基吡啶和2-氨基-5-硝基吡啶的CI-MS-MS分析

二氨基-3-硝基吡啶和2_氨基-5-硝基吡啶的EI—MS质谱图接近，单纯通过Ⅱ-MS质谱图较难区分这两种异构体，作者以甲烷为反应气对2-氨基-3-硝基吡啶和2-氨基-5-硝基吡啶进行化学电离，并利用离子阱质谱的串联质谱技术在离子阱内以He作碰撞气进行碰撞诱导裂解，所得的CI—MS—MS质谱图表明，两者之间存在明显的差别，可用于2-氨基-3-硝基吡啶和2-氨基一5一硝基吡啶的鉴别。     

脂质去除分散固相萃取-超高效液相色谱-串联质谱法测定动物源性食品中5种α2-受体激动剂

采用增强型脂质去除吸附剂(Enhanced Matrix Removal-lipid,EMR-Lipid)对样品进行净化,结合超高效液相色谱-串联质谱(UPLC-MS/MS)检测,建立快速测定动物源性食品中5种α2-受体激动剂(安普乐定、溴莫尼定、替扎尼定、可乐定、赛拉嗪)的方法.对样品前处理方式、质谱及色谱条件进行了...     

脂氧合酶催化双高-γ-亚麻酸脂质过氧化产生的碳自由基的结构确证

采用液相色谱-电子自旋共振波谱(LC/ESR)联用技术、液相色谱-质谱(LC/MS)联用技术结合自旋捕集技术,研究了脂氧合酶(LOX)催化双高-γ-亚麻酸(DGLA)脂质过氧化过程中产生的碳自由基.以α-[4-吡啶基-1-氧]-N-叔丁基氮酮(POBN)为自旋捕集剂,在LOX-DGLA反应混合物中与碳自由基形成自旋加合物后,根据各加合物在LC/UV/ESR和LC/MS中对应的保留时间,确定加合物的分子量,进一步根据加合物质谱裂解方式确定其结构.结果表明,在LOX催化DGLA脂质过氧化过程中产生的碳自由基主要包括~·C_7H_(13)O_2,~·C_(10)H_(17)O_2和~·C_5H_(11),分别来自DGLA脂氧自由基(8-,11-,15-LO~·)的β-裂解.此结果有利于进一步研究DGLA在体内的脂质过氧化过程及该过程中产生的碳自由基的生理作用.     

搅拌棒吸附萃取-热脱附-气相色谱-质谱法测定水中3种烷基酚

应用搅拌棒吸附萃取富集及热解吸进样与气相色谱-质谱相结合测定了水样中3种烷基酚(即正辛基酚、叔辛基酚和正壬基酚)的含量。将水样预先用盐酸调节其酸度至pH 3,分取10.00mL置于顶空瓶中,放入搅拌棒进行吸附萃取。取出搅拌棒,置于热脱附管上解吸并通过程序升温进样系统进样,用DB-5MS柱进行色谱分离。质谱分析条件:电子轰击正离子源,全扫描模式(定性分析)和选择离子扫描模式(定量分析)。3种烷基酚的质量浓度均在5~200ng·L-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)在1.2~2.5ng·L-1之间。以实际水样为基体进行加标回收试验,测得回收率在95.0%~118%之间,测定值的相对标准偏差(n=5)在0.90%~10%之间。     

超高效液相色谱-电喷雾离子源-串联三重四极杆质谱分析饮用水中的高氯酸盐

建立了超高效液相色谱-电喷雾离子源-串联三重四极杆质谱(UPLC-ESI MS/MS)分析饮用水中高氯酸盐的方法.以300Extend-C18为分析柱,10%甲醇水溶液为流动相,ESI MS/MS串联质谱为检测器,以多重反应监测(MRM)模式监测高氯酸盐m/z 99.5→82.9离子对.方法的线性范围为0.2 ～10 μg/L,相关系数为r2=0.999 9,方法检出限为0.15 μg/L,平均加标回收率为82%,相对标准偏差为4.4%.应用UPLC-ESI MS/MS法测定北京市部分城区饮用水中的高氯酸盐,其中5个水样中检出ClO-4,质量浓度为0.040 ～0.262 μg/L,但在安全阈值范围内,不会对居民健康构成威胁.     

凝胶渗透色谱-固相萃取净化-超快速液相色谱-串联质谱法检测牛肉中9种类固醇激素残留

建立了凝胶渗透色谱分离-固相萃取净化-超快速液相色谱-串联质谱 (GPC-SPE-RRLC-MS/MS)测定牛肉中群勃龙、勃地龙、诺龙、睾酮、美雄酮、甲基睾酮、司坦唑醇、黄体酮、苯丙酸诺龙9种类固醇激素残留的方法.试样经β-盐酸葡萄糖醛苷酶/芳基硫酸酯酶酶解,叔丁基甲醚超声提取,凝胶渗透色谱和HLB固相萃取柱净化,以乙腈-0.1%甲酸水溶液为流动相,经Agilent Plus C18柱分离后以MS/MS多反应监测扫描模式检测.方法线性相关系数r＞0.999,定量限为0.2～0.7 μg/kg.在3种浓度添加水平0.3, 1.0, 4.0 μg/kg下,其平均回收率为81.4%～110%;相对标准偏差(RSD)为2.2%～9.8%.本方法已成功应用于高脂肪和基质复杂样品中9种类固醇激素残留的检测.     

吹扫捕集-气相色谱-质谱法测定加油站地下水中特征污染物

采用吹扫捕集-气相色谱-质谱法同时测定加油站地下水中特征污染物甲基叔丁基醚、苯、甲苯、乙苯、二甲苯和萘含量。水样经吹扫捕集浓缩仪处理后,采用HP-5MS型毛细管色谱柱分离,质谱中选择电喷雾离子源-全扫描模式,以氟苯和1,2-二氯苯-D4为内标进行定量。7种化合物的质量浓度在一定范围内与其峰面积呈线性关系,检出限(3S/N)为0.1~0.4μg·L-1。加标回收率在91.0%~105%之间,测定值的相对标准偏差(n=6)在1.1%~3.9%之间。     

Measurement of phospholipids by hydrophilic interaction liquid chromatography coupled to tandem mass spectrometry: the determination of choline containing compounds in foods

A hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC LC-MS/MS) method using multiple scan modes was developed to separate and quantify 11 compounds and lipid classes including acetylcholine (AcCho), betaine (Bet), choline (Cho), glycerophosphocholine (GPC), lysophosphatidylcholine (LPC), lysophosphatidylethanolamine (LPE), phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphocholine (PCho) and sphingomyelin (SM). This includes all of the major choline-containing compounds found in foods. The method offers advantages over other LC methods since HILIC chromatography is readily compatible with electrospray ionization and results in higher sensitivity and improved peak shapes. The LC-MS/MS method allows quantification of all choline-containing compounds in a single run. Tests of method suitability indicated linear ranges of approximately 0.25-25 μg/ml for PI and PE, 0.5-50 μg/ml for PC, 0.05-5 μg/ml for SM and LPC, 0.5-25 μg/ml for LPE, 0.02-5 μg/ml for Cho, and 0.08-8 μg/ml for Bet, respectively. Accuracies of 83-105% with precisions of 1.6-13.2% RSD were achieved for standards over a wide range of concentrations, demonstrating that this method will be suitable for food analysis. 8 polar lipid classes were found in a lipid extract of egg yolk and different species of the same class were differentiated based on their molecular weights and fragment ion information. PC and PE were found to be the most abundant lipid classes consisting of 71% and 18% of the total phospholipids in egg yolk.     

Lipidomics of the Edible Brown Alga Wakame (Undaria pinnatifida) by Liquid Chromatography Coupled to Electrospray Ionization and Tandem Mass Spectrometry

The lipidome of a brown seaweed commonly known as wakame (Undaria pinnatifida), which is grown and consumed around the world, including Western countries, as a healthy nutraceutical food or supplement, was here extensively examined. The study was focused on the characterization of phospholipids (PL) and glycolipids (GL) by liquid chromatography (LC), either hydrophilic interaction LC (HILIC) or reversed-phase LC (RPLC), coupled to electrospray ionization (ESI) and mass spectrometry (MS), operated both in high and in low-resolution mode. Through the acquisition of single (MS) and tandem (MS/MS) mass spectra more than 200 PL and GL of U. pinnatifida extracts were characterized in terms of lipid class, fatty acyl (FA) chain composition (length and number of unsaturations), and regiochemistry, namely 16 SQDG, 6 SQMG, 12 DGDG, 5 DGMG, 29 PG, 8 LPG, 19 PI, 14 PA, 19 PE, 8 PE, 38 PC, and 27 LPC. The FA (C16:0) was the most abundant saturated acyl chain, whereas the monounsaturated C18:1 and the polyunsaturated C18:2 and C20:4 chains were the prevailing ones. Odd-numbered acyl chains, iJ., C15:0, C17:0, C19:0, and C19:1, were also recognized. While SQDG exhibited the longest and most unsaturated acyl chains, C18:1, C18:2, and C18:3, in the sn-1 position of glycerol, they were preferentially located in the sn-2 position in the case of PL. The developed analytical approach might pave the way to extend lipidomic investigations also for other edible marine algae, thus emphasizing their potential role as a source of bioactive lipids.     

Profiling of lipids in Leishmania donovani using hydrophilic interaction chromatography in combination with Fourier transform mass spectrometry

There is evidence from our current research on resistance to stibigluconate and from some previous observations that lipid composition may be altered in resistant Leishmania donovani and in order to explore this we required a comprehensive lipidomics method. Phospholipids can be analysed by direct infusion into a mass spectrometer and such methods can work very well. However, chromatographic methods can also be very effective and are extensively used. They potentially avoid ion suppression effects, associate lipid classes with a retention time range and deliver good quantitative accuracy. In the current study three chromatography columns were compared for their ability to separate different classes of lipid. Butylsilane (C‐4), Zic‐HILIC and a silica gel column were compared. The best results were obtained with a silica gel column used in hydrophilic interaction chromatography (HILIC) mode with a mobile phase gradient consisting of (A) 20% isopropyl alcohol (IPA) in acetonitrile (v/v) and (B) 20% IPA in 0.02 M ammonium formate. Using these conditions separate peaks were obtained for triglycerides (TG), phosphoinositols (PI), inositol phosphoceramides (IPC), phosphatidylethanolamines (PE), phosphatidylserines (PS), phosphatidylcholines (PC), sphingosines (SG), lysophosphatidyethanolamines (LPE) and lysophosphatidylcholines (LPC). The methodology was applied to the analysis of lipid extracts from Leishmania donovani and by coupling the chromatography with an LTQ Orbitrap mass spectrometer. It was possible to detect 188 lipid species in the extracts with the following breakdown: PC 59, PE 38, TG 35, PI 20, CPI 13, LPC 11, LPE 2 and SG 10. The fatty acid composition of the more abundant lipids was characterised by MS² and MS³ experiments carried out by using an LCQ Deca low‐resolution ion trap instrument coupled with the silica gel column. The separation of lipids into well‐defined groups gives extra confidence in their identification and minimises the risk of ion suppression effects. High‐resolution mass spectrometry was necessary in order to be able to differentiate between acyl‐ and acyl‐alkyl‐lipids. Copyright © 2010 John Wiley & Sons, Ltd.     

Identification of glycerophospholipid fatty acid remodeling by using mass spectrometry imaging in bisphenol S induced mouse liver

Exposure to BPS induced glycerophospholipid fatty acid remodeling, which might be useful in toxicity evaluation for bisphenols-induced hepatic diseases.     

Marine Algae Membrane Phospholipids Study by High Resolution 31P NMR

Abstract

Membrane phospholipids were extracted using a modified Folch, Lees and Sloane-Stanley method, from 21 different algae species covering three major divisions of the protista kingdom. In the modified method after chloroform/methanol (2:1 v/v) extraction and filtration, the solution was backwashed with K-EDTA, 0.6 M, instead of KCl, 1 M. Because algae samples are eavily loaded with cations that broaden NMR signals, the K-EDTA wash results in more highly resolved NMR signals. Following rotary evaporation, the crude algae lipid extract was dissolved in the chloroform-benzene(d6)/methanol-CsEDTA (2:l ml/ml) reagent and analyzed using a 500 MHz NMR spectrophotometer. Phospholipid chemical shifts were determined relative to standard phosphoric acid (85%), following the UIPAC convention. The internal reference used was phosphatidylcholine (PC, -0.84 δ) Division chlorophyta (8 sps.) yields phospholipid signals for phosphatidylglycerol (PG, 0.50), phosphatidic acid (PA, 0.25), cardiolipin (CL, 0.18), phosphatidylethanolamine (PE, 0.03), sphyngomyelin (SPH, -0.09), phosphatidylinositol (PI, -0.37) and PC; the lysoderivatives for lyso PG (LPG, 1.09) and lyso PC (LPC, -0.28), and one uncharacterized signal at 0.32. Phosphatidylserine (PS -0.05) and plasmalogens were not detected. Division rhodophyta (10 sps.) shows signal from PG, PA, CL, PE, SPH, PI, and PC; the lysoderivatives of lyso PA (LPA, 0.83), lyso PE (LPE, 0.43) and LPC; the plasmalogens PC plasmalogen (PC plas, -0.77), LPC plas (-0.20), and l-0-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine (PAF-acether, -0.70); and an uncharacterized signal at -40 δ chemical shift. PS was not detected. Division Phaeophytas (3 sps.) showed signals for PG, PA, CL, PE, SPH, PI, and PC and lysoderivatives of LPG, LPA, LPE plas (0.53), LPE, LPC plas, and LPC. PS, PAF-acether and the uncharacterized signals at 0.32 δ and -0.40 δ were not detected.     

Phospholipid Profiles of Neoplastic Human Breast Tissues

Abstract

Membrane phospholipids from malignant, benign and non-involved human breast tissues were extracted by chloroform-methanol (2:l) and analyzed by ³¹P MR spectroscopy at 202.4 MHz. Fourteen phospholipids were identified as constituents of the profiles obtained among the 52 specimens of the three groups: PC, PC plas LPC, LPC plas, PE, PE plas, LPE, PS, SPH, PI, CL, PG, PA and one uncharacterized resonance at 0.13 6. The relative P-lipid profile mole percentages of phosphorus and indices representing sums and ratios of individual or grouped P-lipids were computed and analyzed by one-way analysis of variance and were compared as simple and complex statistical contrasts. The analysis permitted differentiation among the three groups with the most poignant simple contrast being the relative absence of PA in normal tissues, followed by the significant mean mole percentage differences in PC plas between noninvolved (3.09 ± 0.41) and malignant (4.49 ± 0.23) tissues and between these same tissues in the value, of the PC plas/PC index with mean values of 0.07 ± 0.01 and 0.10 ± 0.006, respectively. Significant complex contrasts were seen between the combined neoplastic tissues and noninvolved tissue in PE plas, LPC plas, PC plas and the (PA/Total Phosphatides-PA) index. Differences were also seen between malignant and non-malignant tissues in LPC, the LPC/PC, LPE/PE and PC plas/PC indices. Differentiation among histologically classified human breast tissues is possible with phospholipid profile analysis and metabolic insight.     

Phenylmethanesulfonyl fluoride pretreatment stabilizes plasma lipidome in lipidomic and metabolomic analysis

Though it is standard practice to test the stability of analytes in the matrix for routine bioanalytical method, stability evaluation is always impractical and skipped in untargeted lipidomic and metabolomic analysis because analytes in these studies are enormous, diverse and sometimes unknown. Lipidome represents a major class of plasma metabolome and shows great potential to be diagnostic and prognostic biomarkers. However, lipidome also faces stability problems because plasma contains kinds of lipid degradation enzyme. Here, using liquid chromatography time of flight mass spectrometry based lipidomic methodology, plasma levels of various lipids including triglyceride (TG), diglyceride (DG), free fatty acid (FFA), phosphatidylethanolamine (PE) phosphatidylcholine (PC), lyso-phosphatidylcholine (LPC), lyso-phosphatidylethanolamine (LPE), and sphingomyelin (SM) were dynamically determined within 4 h at ambient temperature. In mouse and rat plasma, the levels of most TG, DG, PC and PE species significantly decreased with respect to time, whereas those of LPC, LPE and FFA significantly increased with respect to time. However, such changes did not occur in human plasma, thus indicating hepatic lipase and esterase might involve in the species-specified degradation of lipid classes in plasma. Phenylmethanesulfonyl fluoride (PMSF) pretreatment prevented such lipidome instability in mouse plasma. The results suggested the instability of plasma lipidome should be highly concerned, and the enhancement of ex vivo stability of plasma lipidome could enable more reliable clinical translation of lipidomic data for biomarker discovery.     

Direct profiling of phospholipids and lysophospholipids in rat brain sections after ischemic stroke

Stroke, a deleterious cerebrovascular event, is caused by a critical reduction in the blood flow to the brain parenchyma that leads to brain injury and loss of brain functions. The inflammatory responses following ischemia often aggravate the neurological damage. Several pro‐inflammatory mediators released after stroke are closely related to the metabolism of phospholipids. In this study we directly profiled the changes in phospholipids in the infarcted rat cerebral cortex 24 hours after middle cerebral artery occlusion (MCAO) using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS). Several phosphatidylcholine (PC) species and sphingomyelin (SM) were significantly decreased after infarction. The cationization pattern of the remaining PCs showed a prominent shift from a mostly potassiated or protonated form to a predominantly sodiated pattern. Stroke also elevated the lysophosphatidylcholines (LPCs) and heme in tissue. The isobaric pairs in PC and LPC classes were resolved by masses through their respective alkali metal adducts in the presence of CsCl. The major fatty acyl LPC species were also structurally confirmed by MALDI‐MS/MS. Overall, the results described the changes in PC and LPC species in the infarcted rat cortex. The elevated tissue levels of LPCs and heme signify the ongoing pathological lipid breakdown and the state of parenchymal inflammation. The elevated LPC level in tissue suggests a means of intervention through lysophospholipid metabolism that could potentially benefit the management of stroke and other acute neurological injuries. Copyright © 2010 John Wiley & Sons, Ltd.     

The Assessment of Changes in the Fatty Acid Profile and Dietary Indicators Depending on the Storage Conditions of Goose Meat

The deterioration of food quality due to lipid oxidation is a serious problem in the food sector. Oxidation reactions adversely affect the physicochemical properties of food, worsening its quality. Lipid oxidation products are formed during the production, processing, and storage of food products. In the human diet, the sources of lipid oxidation products are all fat-containing products, including goose meat with a high content of polyunsaturated fatty acids. This study aims at comparing the fatty acid profile of goose breast muscle lipids depending on the storage conditions: type of atmosphere, temperature, and storage time. Three-way variance analysis was used to evaluate changes in the fatty acids profile occurring in goose meat. The health aspect of fatty acid oxidation of goose meat is also discussed. In general, the fatty acid composition changed significantly during storage in the meat packed in the high-oxygen modified atmosphere at different temperatures (1 °C and 4 °C). Higher temperature led to a higher degree of lipid oxidation and nutrient loss. During the storage of samples in vacuum, no changes in the fatty acid content and dietary indices were found, regardless of the storage temperature, which indicates that the anaerobic atmosphere ensured the oxidative stability of goose meat during 11 days of refrigerated storage.     

Identification of the Fatty Acyl Residues Composition and Molecular Species of Phosphatidylcholines in Soy Lecithin Powder by UPLC–ESI-MS/MS

The fatty acyl residues composition and molecular species of phosphatidylcholines (PCs) in soy lecithin powder were studied and characterized using ultra-performance liquid chromatography-electrospray tandem mass spectrometry (UPLC–ESI-MS/MS) via a two-step procedure. ESI-MS/MS by precursor ion scan (PIS) m/z 184.1 in positive ion mode first detected isobaric PCs, and further identified positional isomers and fatty acyl residue composition in negative ion mode. The results showed that the fatty acyl residue composition was in strong agreement with that detected by the classical analysis method. Likewise, ten peaks of isobaric PCs were obtained by ESI-MS/MS analysis in positive ion mode, and 20 positional isomers of PCs were characterized in negative ion mode. Thus, this study presents a simple and powerful way to analyze fatty acyl residue composition and molecular species of PCs without destroying chemical structure.