电感耦合等离子体质谱技术最新进展

对1998年以来电感耦合等离子体质谱技术（ICP－MS）的最新进展作一简要回顾。内容包括同位素比值分析、双聚焦扇形磁场高分辨ICP－MS、多接收器磁扇形等离子体质谱仪（MC－ICP－MS）、飞行时间等离子体质谱仪（ICP－TOF－MS）、“冷”等离子体及屏蔽炬技术以及动态碰撞／反应池技术等进展。     

Recent advances in supercritical fluid chromatography/mass spectrometry

A summary of the recent advances in SFC/MS is included in this review. Interface designs are described as well as the key control variables. Finally, future developments in SFC/MS are predicted.     

Recent advances of chromatography and mass spectrometry in lipidomics

Lipidomics, as a novel branch of metabolomics, which is aimed at comprehensive analysis of lipids and their biological roles with respect to health and diseases, has attracted increased attention from biological and analytical scientists. As a result of the complexity and diversity of lipids, accurate identification and efficient separation are required for lipidomics analysis. Mass spectrometry (MS) and chromatography have been extensively developed in the past few decades and hold a distinguished position in qualification and separation science. They are powerful and indispensable tools for lipidomics. Herein, we present the recent advancement of MS, chromatography, and their hyphenation technologies in lipidomics.     

Matrix-dependent cationization in MALDI mass spectrometry

The matrix dependence in cationization processes, the competition between cationization and protonation and the question of whether gas-phase cation transfer or attachment of free cations dominates in matrix-assisted laser desorption/ionization mass spectrometry were studied. Two different sample preparation methods were employed, the dried-droplet sample preparation and a mixture of solid matrix, analyte and salt. The latter ensures that the formation of cation adducts takes place in the gas phase. By monitoring the suppression of matrix signals for different matrices, it was found that matrices with high gas-phase metal ion binding energies require high analyte concentrations for matrix suppression to occur. By comparing the mass spectra obtained using sinapinic acid or sinapinic methyl ester as a matrix, a correlation between cationization and deprotonation of matrix molecules was found. It is also demonstrated that attachment of free gas-phase cations, rather than cation transfer from the cationized matrix, is the predominant process in cationization.     

Recent advances in the application of mass spectrometry in food-related analysis

A review is presented on recent applications of mass spectrometry (MS)-based techniques for the analysis of compounds of food concern. Substances discussed are naturally occurring compounds in food products such as lipids, oligosaccharides, proteins, vitamins, flavonoids and related substances, phenolic compounds and aroma compounds. Among xenobiotics, applications of MS techniques for the analysis of pesticides, drug residues, toxins, amines and migrants from packaging are overviewed. Advances in the analysis of trace metals of nutritional and toxicological interest by MS with inductively coupled plasma (ICP) source are presented. The main features of mass spectrometry combined with separation instruments are discussed in food-related analysis. Examples of mass spectrometry and tandem MS (MS-MS) are provided. The development and application of matrix-assisted laser desorption ionization (MALDI) and electrospray (ESI) to the analysis of peptides and proteins in food is discussed. This survey will attempt to cover the state-of-the-art up from 1999 to 2001.     

Recent advances in computational analysis of mass spectrometry for proteomic profiling

The proteome, defined as an organism's proteins and their actions, is a highly complex end-effector of molecular and cellular events. Differing amounts of proteins in a sample can be indicators of an individual's health status; thus, it is valuable to identify key proteins that serve as 'biomarkers' for diseases. Since the proteome cannot be simply inferred from the genome due to pre- and posttranslational modifications, a direct approach toward mapping the proteome must be taken. The difficulty in evaluating a large number of individual proteins has been eased with the development of high-throughput methods based on mass spectrometry (MS) of peptide or protein mixtures, bypassing the time-consuming, laborious process of protein purification. However, proteomic profiling by MS requires extensive computational analysis. This article describes key issues and recent advances in computational analysis of mass spectra for biomarker identification.     

Recent advances of ambient ionization mass spectrometry imaging in clinical research

The structural information and spatial distribution of molecules in biological tissues are closely related to the potential molecular mechanisms of disease origin, transfer, and classification. Ambient ionization mass spectrometry imaging is an effective tool that provides molecular images while describing in situ information of biomolecules in complex samples, in which ionization occurs at atmospheric pressure with the samples being analyzed in the native state. Ambient ionization mass spectrometry imaging can directly analyze tissue samples at a fairly high resolution to obtain molecules in situ information on the tissue surface to identify pathological features associated with a disease, resulting in the wide applications in pharmacy, food science, botanical research, and especially clinical research. Herein, novel ambient ionization techniques, such as techniques based on spray and solid‐liquid extraction, techniques based on plasma desorption, techniques based on laser desorption ablation, and techniques based on acoustic desorption were introduced, and the data processing of ambient ionization mass spectrometry imaging was briefly reviewed. Besides, we also highlight recent applications of this imaging technology in clinical researches and discuss the challenges in this imaging technology and the perspectives on the future of the clinical research.     

Recent advances in mass spectrometry analysis of low molecular weight heparins

Low molecular weight heparins (LMWHs) are the most widely used anticoagulant drugs produced by chemical or enzymatic modification of parent heparin polysaccharides. The present article reviews recent advances in orthogonal and complementary mass spectrometry (MS) methodologies towards complete elucidation of natural and modified structures in LMWHs that possibly affect the drug quality, safety and efficacy.     

Small molecule analysis by MALDI mass spectrometry

This review focuses on the application of matrix assisted laser desorption/ionization (MALDI) mass spectrometry to the characterization of molecules in the low mass range (<1500 Da). Despite its reputation to the contrary, MALDI is a powerful technique to provide both qualitative and quantitative determination of low molecular weight compounds. Several approaches to minimize interference via sample preparation and matrix selection are discussed, as well as coupling of MALDI to liquid and planar chromatographic techniques to extend its range of applicability.     

On-line single droplet deposition for MALDI mass spectrometry

A single droplet generator was coupled with a rotating ball inlet matrix-assisted laser desorption/ionization (MALDI) time of flight (TOF) mass spectrometer. Single droplets with 100 picoliter volume were ejected by a piezoelectric-actuated droplet generator and deposited onto a matrix-coated rotating stainless steel ball at atmospheric pressure. The single droplet deposit was transported to the vacuum side of the instrument where ionization was accomplished using a UV pulsed laser. Using this on-line interface, it was possible to obtain protonated molecule signal from as little as 10 fmol analyte.     

Ultra-thin layer MALDI mass spectrometry of membrane proteins in nanodiscs

Nanodiscs have become a leading technology to solubilize membrane proteins for biophysical, enzymatic, and structural investigations. Nanodiscs are nanoscale, discoidal lipid bilayers surrounded by an amphipathic membrane scaffold protein (MSP) belt. A variety of analytical tools has been applied to membrane proteins in nanodiscs, including several recent mass spectrometry studies. Mass spectrometry of full-length proteins is an important technique for analyzing protein modifications, for structural studies, and for identification of proteins present in binding assays. However, traditional matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) mass spectrometry methods for analyzing full-length membrane proteins solubilized in nanodiscs are limited by strong signal from the MSP belt and weak signal from the membrane protein inside the nanodisc. Herein, we show that an optimized ultra-thin layer MALDI sample preparation technique dramatically enhances the membrane protein signal and nearly completely eliminates the MSP signal. First-shot MALDI and MALDI imaging are used to characterize the spots formed by the ultra-thin layer method. Furthermore, the membrane protein enhancement and MSP suppression are shown to be independent of the type of membrane protein and are applicable to mixtures of membrane proteins in nanodiscs.     

Measurement of neuropeptides in crustacean hemolymph via MALDI mass spectrometry

Neuropeptides are often released into circulatory fluid (hemolymph) to act as circulating hormones and regulate many physiological processes. However, the detection of these low-level peptide hormones in circulation is often complicated by high salt interference and rapid degradation of proteins and peptides in crude hemolymph extracts. In this study, we systematically evaluated three different neuropeptide extraction protocols and developed a simple and effective hemolymph preparation method suitable for MALDI MS profiling of neuropeptides by combining acid-induced abundant protein precipitation/depletion, ultrafiltration, and C₁₈ micro-column desalting. In hemolymph samples collected from the crab Cancer borealis, several secreted neuropeptides have been detected, including members from at least five neuropeptide families, such as RFamide, allatostatin, orcokinin, tachykinin-related peptide (TRP), and crustacean cardioactive peptide (CCAP). Furthermore, two TRPs were detected in the hemolymph collected from food-deprived animals, suggesting the potential role of these neuropeptides in feeding regulation. In addition, a novel peptide with a Lys-Phe-amide C-terminus was identified and de novo sequenced directly from the Cancer borealis hemolymph sample. To better characterize the hemolymph peptidome, we also identified several abundant peptide signals in C. borealis hemolymph that were assigned to protein degradation products. Collectively, our study describes a simple and effective sample preparation method for neuropeptide analysis directly from crude crustacean hemolymph. Numerous endogenous neuropeptides were detected, including both known ones and new peptides whose functions remain to be characterized.     

Flavonoid–matrix cluster ions in MALDI mass spectrometry

The behaviour of 2,5‐dihydroxybenzoic acid (2,5‐DHB) matrix under matrix‐assisted laser desorption/ionisation (MALDI) conditions was investigated, and the formation of 2,5‐DHB cluster ions, mainly dehydrated 2,5‐DHB ions, is reported. Interestingly, in the mass spectra of this compound, besides dimers and trimers, protonated tetramers, pentamers, hexamers and heptamers were also found with significant abundance. The MALDI behaviour of four flavonoids, quercetin, myricetin, luteolin and kaempferol, using 2,5‐DHB as matrix, was also investigated. The mass spectra of the flavonoids studied revealed a number of flavonoid–2,5‐DHB cluster ions (mainly with the dehydrated 2,5‐DHB). The number of clusters formed is dependent on the structure of the analyte. For luteolin and kaempferol, in particular, evidence was found for the formation of cluster ions involving retro Diels Alder fragments and intact flavonoids molecules, as well as the corresponding protonated retro Diels Alder fragments with dehydrated DHB molecules. All ion compositions were attributed taking into account high accuracy mass measurements and tandem mass spectrometry experiments. Copyright © 2009 John Wiley & Sons, Ltd.     

Recent developments in nanoparticle-based MALDI mass spectrometric analysis of phosphoproteomes

Mass spectrometry-based strategies are widely used for mapping of post-translational modifications of phosphoproteins. However, the presence of large amounts of non-phosphopeptides seriously interferes by suppressing the intensities of signals for phosphopeptides in direct MALDI-MS techniques due to the low stoichiometry of protein phosphorylation. Several MALDI-MS approaches are known which use either nanoparticles (NPs) as affinity probes, or NPs as microwave heat absorbers. They assist in the enrichment of trace levels of phosphopeptides from complex protein digests and require minimal sample pretreatment, digestion times, and sample volume. This leads to enhance sensitivity and selectivity in the analysis of the phosphoproteomes. This review (with 89 refs.) summarizes and discusses recent developments in the field, with a particular focus on the potential use of nanomaterials such as metal oxides, metal NPs, NPs-coated target plates, and as core-shell nanocomposites acting as affinity probes and as heat absorbers in MALDI-MS analysis of phosphoproteomes.

完整糖基化肽段的富集与质谱解析新技术研究进展

蛋白质糖基化是生物体内最重要的翻译后修饰之一,在蛋白质稳定性、细胞内和细胞间信号转导、激素活化或失活和免疫调节等生理过程和病理进程中发挥重要作用.而异常的蛋白质糖基化往往和多种疾病的发生发展密切相关,目前应用于临床检测的多种肿瘤生物标志物大多属于糖蛋白或者糖抗原.因此在组学层次系统分析蛋白质糖基化的变化对阐明生物体内糖...     

多接收器电感耦合等离子体质谱方法的开发和应用进展

稳定同位素分析是分析化学一项颇具前景的分支,通过精确测定物质的稳定同位素比值,可以追溯物质来源并探究其转化过程。高精度稳定同位素分析技术的进步依赖于新一代质谱仪的不断发展。其中,多接收器电感耦合等离子体质谱(MC-ICP-MS)是近年发展迅速的一种同位素组成测定工具。稳定同位素分析对样品基质十分敏感,复杂基质能严重干扰同位素测定的精密度和准确度。这对MC-ICP-MS的样品净化提出了极高要求,目前也是同位素分析领域的热点问题。该文聚焦于近年来MC-ICP-MS在样品净化及仪器联用方法方面的相关研究进展,并展望了MC-ICP-MS稳定同位素分析的应用前景。     

Ionic liquid matrices for MALDI mass spectrometry of lignin

Analytical and Bioanalytical Chemistry - The use of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry for the study of lignin is still extremely limited due to its low...     

Rapid fingerprinting of red wines by MALDI mass spectrometry

Here we report a simple and fast method for wine fingerprinting based on direct matrix-assisted laser desorption/ionization (MALDI) mass spectrometry analysis of different red wine samples, useful for batch-to-batch analysis and for the detection of key compounds even in trace amounts which may vary from vintage to vintage, and from one treatment to another one. A series of 20 samples from different wines were subjected to MALDI mass spectrometry. We found that 2,5-dihydroxybenzoic acid is far superior with respect to all the matrices tested To the best of our knowledge this is the first application of an effective wine profiling not limited to detection of anthocyanins. More than 80 molecular species were detected. Moreover, qualitative and quantitative differences were observed, owing to the nature and relative abundance of different chemical compounds among the wines.