High-Throughput Analysis of Algal Crude Oils Using High Resolution Mass Spectrometry

Lipid analysis often needs to be specifically optimized for each class of compounds due to its wide variety of chemical and physical properties. It becomes a serious bottleneck in the development of algae-based next generation biofuels when high-throughput analysis becomes essential for the optimization of various process conditions. We propose a high-resolution mass spectrometry-based high-throughput assay as a ‘quick-and-dirty’ protocol to monitor various lipid classes in algal crude oils. Atmospheric pressure chemical ionization was determined to be most effective for this purpose to cover a wide range of lipid classes. With an autosampler-LC pump set-up, we could analyze algal crude samples every one and half minutes, monitoring several lipid species such as TAG, DAG, squalene, sterols, and chlorophyll a. High-mass resolution and high-mass accuracy of the orbitrap mass analyzer provides confidence in the identification of these lipid compounds. MS/MS and MS3 analysis could be performed in parallel for further structural information, as demonstrated for TAG and DAG. This high-throughput method was successfully demonstrated for semi-quantitative analysis of algal oils after treatment with various nanoparticles.     

Chemical Characterization of Sorbitan Tri-Stearate Commercial Samples and Their Determination in Confectionery Fats by HPLC High-Resolution Mass Spectrometry

Nominal sorbitan tristearate (E492) commercial samples are widely used generally as emulsifiers and particularly as anti-bloom agents in confectionery products. In spite of this generalized use, their qualitative and quantitative evaluation is poorly documented in literature and the relative works go back to the last decades of last century. In the present work, a deep study by HPLC-High Resolution Mass Spectrometry of qualitative composition of five E492 commercial samples was made up showing a very complex pattern of stearic and palmitic acid esters with the sorbitol anhydrides, sorbitan, and isosorbide. A clear distinction of sorbitan mono-, di-, tri-, and tetra-esters, of sorbitol penta- and hexa-esters and isosorbide mono- and di-esters was achieved. Contemporarily, difference in the qualitative pattern between E492 commercial samples coming from different suppliers was established. As a consequence, quantitative evaluation can be reliably obtained by using as calibration standard the same E492 present in real samples. The accuracy and recovery of the method were determined allowing in this way a reliable application to commercial confectionery products. The detailed knowledge of STS composition may be of great help to orient the synthesis conditions in order to modulate its properties as a function of various experimental necessities.     

聚环氧丙烷的电喷雾质谱分析

采用电喷雾质谱（ESI—MS）分析得到了聚环氧丙烷（PPO）的一级质谱和二级质谱。通过正负2种离子化模式计算一级质谱中各分子离子峰m／z的差值为58,证实了单体为环氧丙烷（PO）。并在二级质谱中通过对一些化合物碎片峰的解析,得到了PPO的裂解方式。同时利用碎片分析,推断出此PPO起始剂为丙三醇。     

微波萃取-气相色谱质谱法测定塑料中的氯苯类化合物

本研究建立了微波萃取-气相色谱质谱法测定塑料中12种氯苯类化合物的分析方法。该方法以正己烷和丙酮混合溶剂(V/V=1/1)为提取剂,微波萃取后用佛洛里硅土柱净化,气相色谱质谱进行定量分析。结果表明:在5~500 ng/ml浓度范围内12种氯苯类化合物线性良好,检出限为0.5~3.8μg/kg。在3个添加水平下,平均回收率分别为74.8%~87.3%、80.6%~92.2%、90.9%~104.1%,相对标准偏差分别为2.94%~9.09%、1.46%~6.24%、1.77%~5.64%。     

杀虫双的液相色谱-质谱分析

建立了用液相色谱串联质谱定量检测杀虫双残留的方法,考察酸碱度对杀虫双形态的影响.结果表明:液相色谱-质谱选择反应监测技术定量检测鱼组织中的杀虫双残留,其线性范围为10.96～10 960μg/L,检出限为21.92μg/kg,回收率为92.8%;杀虫双在pH值小于3或大于9时会发生水解,形成多种水解产物,因此在杀虫双检测过程中控制酸碱度是至关重要的.     

VDACs Post-Translational Modifications Discovery by Mass Spectrometry: Impact on Their Hub Function

VDAC (voltage-dependent anion selective channel) proteins, also known as mitochondrial porins, are the most abundant proteins of the outer mitochondrial membrane (OMM), where they play a vital role in various cellular processes, in the regulation of metabolism, and in survival pathways. There is increasing consensus about their function as a cellular hub, connecting bioenergetics functions to the rest of the cell. The structural characterization of VDACs presents challenging issues due to their very high hydrophobicity, low solubility, the difficulty to separate them from other mitochondrial proteins of similar hydrophobicity and the practical impossibility to isolate each single isoform. Consequently, it is necessary to analyze them as components of a relatively complex mixture. Due to the experimental difficulties in their structural characterization, post-translational modifications (PTMs) of VDAC proteins represent a little explored field. Only in recent years, the increasing number of tools aimed at identifying and quantifying PTMs has allowed to increase our knowledge in this field and in the mechanisms that regulate functions and interactions of mitochondrial porins. In particular, the development of nano-reversed phase ultra-high performance liquid chromatography (nanoRP-UHPLC) and ultra-sensitive high-resolution mass spectrometry (HRMS) methods has played a key role in this field. The findings obtained on VDAC PTMs using such methodologies, which permitted an in-depth characterization of these very hydrophobic trans-membrane pore proteins, are summarized in this review.     

高效液相色谱-串联质谱法同时检测蔬菜、水果中21种农药多残留

建立了以固相萃取/高效液相色谱-串联质谱(LC/MS/MS)同时测定蔬菜、水果中痕量21种农药残留量的方法.蔬菜、水果样品提取液经固相萃取后采用C18柱分离,以0.1%甲酸乙腈-0.1%甲酸水溶液为流动相,梯度洗脱,以保留时间和质荷比对分离出的组分予以定性确证,用峰面积进行定量.结果表明,21种农药的质量浓度与其峰面积在一定的范围内呈良好的线性关系,样品中最低检出质量分数为0.0005～0.003 mg/kg,样品的平均加标回收率为76.34%～119.33%.方法简便、快速、灵敏,适用于蔬菜、水果中这些农药的同时分析.     

Mass Spectrometry Methodology in Lipid Analysis

Lipidomics is an emerging field, where the structures, functions and dynamic changes of lipids in cells, tissues or body fluids are investigated. Due to the vital roles of lipids in human physiological and pathological processes, lipidomics is attracting more and more attentions. However, because of the diversity and complexity of lipids, lipid analysis is still full of challenges. The recent development of methods for lipid extraction and analysis and the combination with bioinformatics technology greatly push forward the study of lipidomics. Among them, mass spectrometry (MS) is the most important technology for lipid analysis. In this review, the methodology based on MS for lipid analysis was introduced. It is believed that along with the rapid development of MS and its further applications to lipid analysis, more functional lipids will be identified as biomarkers and therapeutic targets and for the study of the mechanisms of disease.     

Determination of Bile Acids in Piglet Bile by Solid Phase Extraction and Liquid Chromatography-Electrospray Tandem Mass Spectrometry

An LC/MS/MS‐based method was developed for the determination of individual bile acids (BA) and their conjugates in porcine bile samples. The C18‐based solid‐phase extraction (SPE) procedure was optimized so that all 19 target BA and their glycine and taurine conjugates were collected with high recoveries for standards (89.1–100.2 %). Following this, all 19 compounds were separated and quantified in a single 12 min chromatographic run. The method was validated in terms of linearity, sensitivity, accuracy, precision, and recovery. An LOD in the low ppb range with measured precisions in the range of 0.5–9.3 % was achieved. The recoveries for all of the 19 analytes in bile samples were all >80 %. The validated method was successfully applied to the profiling of BA and their conjugates in the bile from piglets treated with exogenous glucagon‐like peptide‐2 (GLP‐2) in a preclinical model of neonatal parenteral nutrition‐associated liver disease (PNALD). The method developed is rapid and could be easily implemented for routine analysis of BA and their conjugates in other biofluids or tissues.     

Nanoparticle Detection by Aerosol Mass Spectrometry

An aerodynamic lens system with efficient transmission of particles in the 10-300 nm size range is used to study the efficiency of nanoparticle detection by laser ablation mass spectrometry with 193 nm and 266 nm radiation. Ideally, all particles in the beam path when the laser fires should be detected. However, the probability of particle detection is much less than 1 and dependent upon the particle type, defined by particle size and chemical composition, and the ablation conditions, defined by the laser wavelength and irradiance. Particles above 100 nm can be ablated and detected with near unit efficiency. Below 100 nm, the detection probability decreases with decreasing particle size and salt particles (sodium chloride, potassium chloride) are detected with higher efficiency than organic particles (oleic acid, 3-nitrobenzyl alcohol). The results are discussed in relation to the mechanism of laser ablation and the instrumental requirements for particle detection.     

二次离子质谱分析研究进展

二次离子质谱是一种用于分析固体材料表面组分的重要手段,广泛应用于化学、生物学、微电子、陶瓷、新材料研究等领域.基于二次离子质谱测试原理,分析了其在材料研究过程中的定性分析、杂质定量分析、深度剖面分析、分布成分分析等,为材料研究同行提供借鉴.     

Particle Analysis by Laser Mass Spectrometry WB-57F Instrument Overview

Recently, a second version of the Particle Analysis by Laser Mass Spectroscopy (PALMS) instrument was constructed to fly in the nose of a WB-57F research aircraft, allowing it to make in-situ measurements of stratospheric aerosols. We present here the technical aspects of the design and construction of the PALMS aircraft instrument. These include the development of a robust and complex data acquisition and control software program, a stable optical system with in-flight correction, the mechanical packaging required for in-flight operation, a shrouded inlet designed for optimal particle sampling, and custom and commer cial electronics. We also present a brief review of the performance of the PALMS instrument during its first deployment in the WB-57F.     

电感耦合等离子体质谱法定量分析中干扰的消除

探讨了干扰的类型以及干扰效应的作用原理.以内标法降低基体性干扰,串联四级杆质量分析器与碰撞反应池,以碰撞模式(He)或反应模式(H2/O2/NH3)消除同量异位素、双电荷以及分子离子等质谱型干扰.以ICP-MS/MS两种分析模式(On-mass模式和Mass Shift模式)为例介绍了干扰消除的具体应用.     

裂解气相色谱/质谱联用仪分析RT培司的杂质

采用裂解气相色谱/质谱联用(Py-GC/MS)仪分析RT培司(对氨基二苯胺)所含的杂质。结果表明:将RT培司和疑似杂质的导热油样品直接进样,通过GC谱峰的保留时间和MS谱的特征离子推断RT培司样品中的杂质为导热油。RT培司生产过程应避免此类物质的污染,以提高产品纯度。     

基于热重-质谱联用技术测定EVA的方法探究

乙酸乙烯酯-乙烯共聚物乳胶粉(EVA)应用广泛,其检测技术的发展至关重要。本研究利用热重-质谱联用技术(TG-MS),在质量维度上建立了一种对EVA进行定量分析的方法。通过热重-红外-气质联用仪探究了EVA的热解过程,结果表明EVA的热解可分为三个阶段,其中第二阶段脱乙酰化步骤产生大量的乙酸能被清晰识别,同时在此步骤中也有低分子量的(CH)_n碎片和丙酮产生。随着热解温度升高,分子量较大的苯环衍生物和(CH)_n碎片在高温下被检测到。这表明在脱乙酰过程中聚合物主链末端发生了断链反应,随着温度的升高,不饱和烯烃结构热解产生芳香挥发物。通过在线质谱监测等温脱乙酰化反应,确定酮类物质的生成并不会影响脱乙酰化反应的进行,因此使用乙酸对EVA进行定量分析是合理的。通过MS信号与乙酸质量关联,建立了EVA的定量分析方法,为分析样品中EVA的定量检测提供了一种新方案。     

A Click-Chemistry-Based Enrichable Crosslinker for Structural and Protein Interaction Analysis by Mass Spectrometry

Mass spectrometry is the method of choice for the characterisation of proteomes. Most proteins operate in protein complexes, in which their close association modulates their function. However, with standard MS analysis, information on protein–protein interactions is lost and no structural information is retained. To gain structural and interactome data, new crosslinking reagents are needed that freeze inter- and intramolecular interactions. Herein, the development of a new reagent, which has several features that enable highly sensitive crosslinking MS, is reported. The reagent enables enrichment of crosslinked peptides from the majority of background peptides to facilitate efficient detection of low-abundant crosslinked peptides. Due to the special cleavable properties, the reagent can be used for MS² and potentially for MS³ experiments. Thus, the new crosslinking reagent, in combination with high-end MS, should enable sensitive analysis of interactomes, which will help researchers to obtain important insights into cellular states in health and diseases.     

3D Molecular Imaging of Stratum Corneum by Mass Spectrometry Suggests Distinct Distribution of Cholesteryl Esters Compared to Other Skin Lipids

The crucial barrier properties of the stratum corneum (SC) depend critically on the design and integrity of its layered molecular structure. However, analysis methods capable of spatially resolved molecular characterization of the SC are scarce and fraught with severe limitations, e.g., regarding molecular specificity or spatial resolution. Here, we used 3D time-of-flight secondary ion mass spectrometry to characterize the spatial distribution of skin lipids in corneocyte multilayer squams obtained by tape stripping. Depth profiles of specific skin lipids display an oscillatory behavior that is consistent with successive monitoring of individual lipid and corneocyte layers of the SC structure. Whereas the most common skin lipids, i.e., ceramides, C24:0 and C26:0 fatty acids and cholesteryl sulfate, are similarly organized, a distinct 3D distribution was observed for cholesteryl oleate, suggesting a different localization of cholesteryl esters compared to the lipid matrix separating the corneocyte layers. The possibility to monitor the composition and spatial distribution of endogenous lipids as well as active drug and cosmetic substances in individual lipid and corneocyte layers has the potential to provide important contributions to the basic understanding of barrier function and penetration in the SC.     

药用中间体苯丙酮含量的气相色谱/质谱分析

苯丙酮是合成利胆药苯丙醇的重要中间体。本文建立了用气相色谱 /质谱法 (GC/MS)测定苯丙酮含量的方法。组分的定性依靠GC/MS联用技术和NIST谱库标准质谱图对照分析。以苯乙酮为内标 ,苯丙酮含量在 1.0× 10 -5～ 2 .0× 10 -4g/mL范围内呈线性 ,线性相关系数r =0 .994 9,苯丙酮最低检测浓度为 1.0× 10 -8g/mL。该法操作简便、快速 ,结果准确可靠 ,且具有很好的实用价值     

Mechanistic Investigation of Photochemical Reactions by Mass Spectrometry

This Minireview highlights the application of electrospray ionization mass spectrometry (ESI-MS) to investigating photochemical reactions. We show possible approaches to on-line ESI-MS monitoring of photocatalytic reactions and give examples of the characterization of short-lived photochemical intermediates by ion spectroscopy. The minireview also exemplifies in-depth mass spectrometric studies of photoisomerization reactions and photofragmentation reactions. Apart from mechanistic studies, the coupling of photochemistry and mass spectrometry is a powerful approach to studying structure and properties of biomolecules. We show several examples focused on investigation of intrinsic properties of model biomolecules.