Application of off-line size-exclusion chromatographic fractionation-matrix assisted laser desorption ionization time of flight mass spectrometry for proanthocyanidin characterization

In this work, we wanted to devise a reliable method to characterize polymerized forms of tannins, their structural information and mass distribution. Size-exclusion chromatography (SEC) is a chromatographic technique used to determine molecular mass (weight) distributions of polymers. One important step in the data treatment is the modeling of the calibration curves. Polystyrenes (PS) are standards usually used because no commercial procyanidin (PC) standards are available. An off-line coupling of SEC and MALDI was carried out to measure differences between polystyrenes and procyanidins. Thus, a new calibration curve was established; from 1000 to 8000 Da, there is a good correlation between the MALDI and PS calibration curves, in this field the PS calibration is correct and enables true mass determination. For masses above 8000 Da, PS calibration overestimates the real molecular weight of PC, overestimation of 53%. And for masses below 1000 Da, PS calibration underestimates their real molecular weight (10-15%). This means that to truly characterize PC, calibration based on PC standards is required.     

液相色谱/电喷雾质谱(LC/ESI/MS)在蛋白质分析鉴定中的应用

对液相色谱／电喷雾质谱（LC／ESI／MS）在蛋白质分子量测定、一级结构的分析、蛋白质和多肽纯度的鉴定、肽质量酶谱、蛋白质分子内二硫键的定量和定位、磷酰化位置的测定以及在蛋白质组中的应用等方面进行了综述和讨论。     

Comparison of Electrospray Ionization and Fast Atom Bombardment Mass Spectrometry for the Analysis of Saponins from Alfalfa,Clover, and Mungbeans

The determination of seven saponins in crude plant extracts by electrospray ionization mass spectrometry (ESI-MS) and fast atom bombardment mass spectrometry (FAB-MS) is described. Distinct protonated and natriated (Na-adduct) molecular ions in ESI-MS spectra readily provide molecular weight information, which can be further verified using clusters of molecular ions. Saponin mixtures can be analyzed by ESIMS on varying the potential difference between the capillary and skimmer in the ESI source to decompose impurities. ESI-MS uses less amount of sample than that required by FAB-MS. ESI-MS does not produce structural information, however. The FAB-MS spectra consist mainly of protonated and deprotonated molecular ions with limited structural information. (-)-FAB-MS is more suitable for analyzing saponin samples than the (+)-FAB-MS.     

电喷雾质谱法测定牛血清白蛋白相对分子质量及测定结果的不确定度评估

对直接流动注射电喷雾质谱法和LC-MS联用电喷雾质谱法测定牛血清白蛋白相对分子质量的测定结果进行比对,并评估了测定结果的不确定度。直接流动注射法和LC-MS联用法测定牛血清白蛋白相对分子质量的扩展不确定度分别为20.8和12.0,LC-MS联用电喷雾质谱法具有较小的A类不确定度并且测定结果的中心值与理论值更为接近。两种方法均可以用于相对分子质量在10000~80000蛋白质的相对分子质量的测定。     

电喷雾质谱在非共价生物—有机分子复合物研究中的应用

大量实验证明能够准确测定生物大分子分子量（２０，０００Ｄａ）的电喷雾质谱在分析溶液中生物化学作用方面有着巨大的潜力。本文综述了电喷雾质谱在分析液中特异性非共价生物－有机分子复合物方面的应用。     

ESI-MS测定牛血清白蛋白分子量过程中的pH影响

在电喷雾质谱测定牛血清白蛋白分子量的过程中,适当调整样品溶液的酸度,可提高分析测试的灵敏度.在选定最佳样品浓度的基础上,通过适当加入冰醋酸来调整测试样品的pH值,准确测定了标准蛋白质——牛血清白蛋白的分子量.     

研究级激光微探针飞行时间质谱仪及其应用

本文介绍了自行研制的激光微探针飞行时间质谱仪，阐述了该仪器的基本原理、结构特点、研究功能及其所达到的参量。该仪器是一台具有高分辩率、高灵敏度、研究功能强并兼具常规分析所需的简便、快捷的现代大型分析仪器。文章还介绍了该仪器的应用实例，如可作几万道尔顿以上的大分子物质分析，大分子蛋白质混合物的分析，有机化合物特别是难挥发和热不稳定有机物的分析，少至几十埃薄膜，如Ｃ６０等薄膜材料成分分析，负离子分析，以     

质谱技术在蛋白质、多肽化学中的应用

文中介绍了几种新的质谱技术: 快原子轰击质谱(fast atom bombardment-MS, 简称FAB-MS)、串联质谱(tandem mass spectrometry, 简称MS/MS)、电喷雾电离质谱(electrospray ionization-MS, 简称ESI-MS)和基质辅助的激光解吸电离飞行时间质谱(matrix assisted laser desorption ionization time offlight MS, 简称MALDI-TOF-MS), 这几种技术的相互补充使得质谱比较有效地用于蛋白质结构测定。文中例举了几个实例说明了它们在蛋白质的分子量测定,蛋白质和多肽的纯度鉴定, 糖肽的结构测定及特殊的N-端封闭的或一般的蛋白质和多肽的顺序测定中的应用。     

Detailed structural elucidation of polyesters and acrylates using Fourier transform mass spectrometry

The detailed structural characterization of complex polymer architectures, like copolymers and polymer mixtures, by mass spectrometry presents a challenge. Even though soft ionization analyses revolutionized the characterization of large molecules and provided a means for determining the polymer’s molecular weight distribution, polydispersity, and end groups, full microstructure elucidation and monomer sequencing by soft ionization alone is not possible. The combination of high-resolution Fourier transform mass spectrometry (FTMS) and tandem mass spectrometry (MSⁿ) provides a powerful analytical tool for addressing these challenges. This tool was used in our work to separate and identify the products of polymerization between 12-hydroxystearic acid (HSA) and stearic acid (SA), to provide precise information about the exact location of caprolactones on the Tris(2-hydroxyethyl)isocyanurate (THEIC) molecule, and to sequence a glycidyl methacrylate/methyl methacrylate (GMA/MMA) copolymer. The results highlight the value of ultrahigh resolution and tandem mass spectrometry for fine structural characterization and sequencing of polymers.     

凝胶色谱法测定聚丙烯腈相对分子质量的验证

采用窄分布的聚苯乙烯和聚甲基丙烯酸甲酯分别对凝胶色谱柱进行标定,测定了聚丙烯腈的相对分子质量。聚苯乙烯、聚甲基丙烯酸甲酯标定法得到聚丙烯腈的重均相对分子质量分别为5.008×10^5,2.929×10^5,两种标定方法所得数据相差较大。采用光散射法验证窄分布标准样品标定测试数据的准确度,得到聚丙烯腈的重均相对分子质量为1.485×10^5,与窄分布聚合物标定凝胶色谱法得到的数据相差很大,表明凝胶色谱标定法测定聚丙烯腈的相对分子质量是一种相对方法,其量值无法实现准确溯源。     

Mass spectrometric methods: an answer for macromolecule analysis in the 1990s

The field of mass spectrometry is now well developed for solving analytical and structural problems involving substances with molecular weights less than ca. 1000. The future challenge for mass spectrometry is in the area of macromolecule analysis and structural biology. This challenge will be met on two fronts. One is structural analysis of pieces of macromolecules, a task for tandem mass spectrometers. Tandem sector instruments offer sufficient control, reproducibility of results and ease of set-up that they will play a major role in structure studies. When designed to operate with extended array detectors, tandem sector instruments will also offer subpicomole detection limits. The second front is molecular weight measurements. Exciting advances include matrix-assisted laser desorption and electrospray ionization. The need for better means of mass analysis is forecast, and it is suggested that the Fourier transform mass spectrometer can meet the challenge. Success awaits a better understanding of the dynamics of high-mass ions. One route to improved understanding is outlined.     

基体辅助激光解吸电离飞行时间质谱用于寡糖的分析

将基体辅助激光解吸电离飞行时间质谱这种新兴的质谱方法用于植物中寡糖的分析。比较了不同的样品制备方法和检测方法对分析结果的影响,给出各寡糖样品的分子量分布,单体和端基基团的分子量。     

人参皂苷的基质辅助激光解吸质谱研究

利用MALDI-TOFMS测定了八种人参皂苷的分子量, 并分析了西洋参总皂苷的组成。同时, 进行了灵敏度实验, 并探讨了基质及碱金属离子的影响, 证明该方法灵敏度高, 重复性好, 结果准确。是测定极性小分子分子量的有效方法。     

用基质辅助激光解吸电离飞行时间质谱法测定钙调蛋白的纯度与分子量

采用基质辅助激光解吸电离飞行时间质谱法测定了钙调蛋白的纯度与分子量,并对所得的结果进行了讨论,实验结果表明本方法具有灵敏度高,分析速度快,重复性好,信息直观等特点,是其他传统测定蛋白质分子量的方法无法比拟的。     

液相色谱-电喷雾电离质谱与电子轰击质谱联用筛选百合中的甾体皂甙

 利用高效液相色谱 电喷雾电离质谱联用仪 (HPLC/ESI MS)、电子轰击质谱 (EI MS)和半制备型高效液相色谱 ,从卷丹百合中筛选出了两种甾体皂甙 ,其中一种为含有 3个糖基与提果皂甙元的甾体皂甙 ,另一种为含有 3个糖基和薯蓣皂甙元的甾体皂甙。结果表明 :在线的HPLC/ESI MS能够准确快速地提供糖甙类化合物的分子质量和糖链部分的有益信息 ,但对甙元部分提供的信息极少 ;离线的EI MS只需极少量 (1mg～ 2mg)的纯品就能准确地提供甙元部分的有益信息 ,但很难获得糖甙的分子离子峰与糖链部分的信息 ,两者有机地结合起来能快速地从植物中筛选甾体皂甙。     

Ultraviolet femtosecond laser ionization mass spectrometry

For this study, multiphoton ionization/mass spectrometry using an ultraviolet (UV) femtosecond laser was employed for the trace analysis of organic compounds. Some of the molecules, such as dioxins, contain several chlorine atoms and have short excited-state lifetimes due to a "heavy atom" effect. A UV femtosecond laser is, then, useful for efficient resonance excitation and subsequent ionization. A technique of multiphoton ionization using an extremely short laser pulse (e.g., <10 fs), referred to as "impulsive ionization," may have a potential for use in fragmentation-free ionization, thus providing information on molecular weight in mass spectrometry.     

Ultrasonic energy as a tool in the sample treatment for polymer characterization through matrix-assisted laser desorption ionization time-of-flight mass spectrometry

Different ultrasonic devices including ultrasonic bath with dual frequency, sonoreactor and ultrasonic probe, were tested for their viability in the sample treatment for polymer characterization by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis. The effect of sonication frequency (35 kHz, 40 kHz and 130 kHz), sonication amplitude, and sonication time on the polymer's number-average molecular weight (M_n) and weight-average molecular weight (M_w) were investigated. The effect of those variables in the molecular mass distribution of three polymer standards, poly(styrene) 2000 Da and 10,000 Da and poly(ethylene glycol) 1000 Da, was evaluated. In addition, the influence of ultrasonic energy on the sample treatment as a function of the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI) matrix was also studied through two common standard matrices, dithranol and 2,5-dihydroxybenzoic acid. The results obtained show that the ultrasonic bath at 35 kHz is the best option for the purpose of fast sample treatment for polymer characterization. The M_n and M_w values obtained for this ultrasonic device and for the three polymers tested using dithranol as MALDI matrix, were not statistically different from the ones acquired with vortex mixing and also were in concordance with the values recommended by the polymer manufacturers.     

液相色谱/质谱/质谱联用鉴定赤芍中的一种新化合物

利用液相色谱-串联质谱联用技术，鉴定了赤芍中分子量为496的两种化合物。研究了芍药甙的二级质谱断裂行为来帮助鉴定已知化合物氧化芍药甙。通过比较不同碰撞能量下的未知化合物子和氧化芍药甙的离子碎片，确定了未知化合物的基本结构单元。借助紫外光谱初步确定此未知化合物为邻位氧化芍药甙，是已报道活性成分对位氧化芍药甙的同分异构体。这是邻位氧化芍药的甙的首次报道。     

Current applications of capillary electrophoresis-mass spectrometry for the analysis of biologically important analytes in urine (2017 to mid-2021): A review

Capillary electrophoresis coupled online with mass detection is a modern tool for analyzing wide ranges of compounds in complex samples, including urine. Capillary electrophoresis with mass spectrometry allows the separation and identification of various analytes spanning from small ions to high molecular weight protein complexes. Similarly to the much more common liquid chromatography-mass spectrometry techniques, the capillary electrophoresis separation reduces the complexity of the mixture of analytes entering the mass spectrometer resulting in reduced ion suppression and a more straightforward interpretation of the mass spectrometry data. This review summarizes capillary electrophoresis with mass spectrometry studies published between the years 2017 and 2021, aiming at the determination of various compounds excreted in urine. The properties of the urine, including its diagnostical and analytical features and chemical composition, are also discussed including general protocols for the urine sample preparation. The mechanism of the electrophoretic separation and the instrumentation for capillary electrophoresis with mass spectrometry coupling is also included. This review shows the potential of the capillary electrophoresis with mass spectrometry technique for the analyses of different kinds of analytes in a complex biological matrix. The discussed applications are divided into two main groups (capillary electrophoresis with mass spectrometry for the determination of drugs and drugs of abuse in urine and capillary electrophoresis with mass spectrometry for the studies of urinary metabolome).