Determination of Phenolic Compounds by Capillary Zone Electrophoresis–Mass Spectrometry

A CZE-MS method was developed for the determination of several phenolic compounds (phenolic acids, flavonoids). Since the analysis of these components necessitates the application of basic conditions for CZE separation and negative ionization mode for MS detection, the simplest choice was to use 0.5 M NH₄OH and IPA:water (1:1 v/v%) as the background electrolyte and sheath liquid, respectively. The LOD values ranged between 0.004–1.9 mg/L showing that there are relatively large differences in the ionization (and chemical) features of these compounds. The precision data were better than 0.75 RSD% for migration times and were between 5–8 RSD% for peak areas. In order to test the applicability of the developed method, a honey sample was analyzed.     

Direct Mass Spectrometry Analysis of Biofluid Samples Using Slug‐Flow Microextraction Nano‐Electrospray Ionization

Direct mass spectrometry (MS) analysis of biofluids with simple procedures represents a key step in the translation of MS techniques to clinical and point‐of‐care applications. The current study reports the development of a single‐step method using slug‐flow microextraction and nano‐electrospray ionization for MS analysis of organic compounds in blood and urine. High sensitivity and quantitation precision have been achieved in the analysis of therapeutic and illicit drugs in 5 μL samples. Real‐time chemical derivatization has been incorporated for analyzing anabolic steroids. The monitoring of enzymatic functions has also been demonstrated with cholinesterase in wet blood. The reported study encourages the future development of disposable cartridges, which function with simple operation to replace the traditional complex laboratory procedures for MS analysis of biological samples.     

纳升电喷雾毛细管液相色谱-串联质谱鉴定K562细胞株中混合蛋白质

用标准蛋白质混合物建立了一种适用于低丰度混合蛋白质及其异构体分离与鉴定的蛋白质组学方法。通过IPG胶条等电聚焦分离蛋白质,染色后进行混合胶内酶切,采用纳升电喷雾毛细管液相色谱一串联质谱“散弹法（shot-gun）”分析酶切产物,并进行数据库检索鉴定蛋白质。运用该方法从K562细胞株样品中鉴定出14种具有重要功能的蛋白质,部分蛋白质同时在多个条带中出现,可能是异构体。肽段及其碎片离子的平均质量偏差小于0．05U,综合得分大都远远超过有效值。该方法灵敏、准确度高、分辨率高、省时、便于操椎存苍宗罾白甩异构体青而右优势．     

Analysis of Sulfonamides by Liquid Chromatography Mass Spectrometry and Capillary Electrophoresis Combing with Voltage‐Assisted Liquid‐Phase Microextraction

The method of liquid‐phase microextraction assisted with voltage was developed and applied on determination of sulfonamides in water samples. Four analytes, such as sulfamethazine, sulfathiazole, sulfadimethoxine, and sulfamethoxazole were extracted from a sample solution at pH 4.5 through a polypropylene membrane of immobilized with 2‐octanone, and then into 25 μL of the acceptor phase of 10 mM sodium hydroxide, and applied voltage of 100 V. Subsequently, the acceptor solution was directly subjected to analysis by LC‐MS or capillary zone electrophoresis. Linearity was obtained in the range of 1.0–25.0 ng mL^?1 with R² > 0.992 in LC‐MS, and 50–1000 ng mL^?1 with R² > 0.995 in capillary zone electrophoresis. The development of VA‐LPME was also applied in analysis of sulfonamides in water samples to evaluate its practical applicability.     

高效毛细管电泳联用电喷雾-质谱法研究新型抗癌铂配合物的稳定性

研究了新型抗癌铂配合物3,5-二异丙基水杨酸-1,2-环己二胺合铂(Ⅱ)(SM54111)在溶液中的稳定性.采用高效毛细管电泳(HPCE)法,分离在pH 3.7～9.0的缓冲液中铂配合物与其降解产物,联用电喷雾质谱(ESI-MS/MS)检测,确证降解产物的结构.结果表明,SM54111溶液,在pH 5.0～9.0时基本稳定,pH《5.0时发生解离反应.证实该新型抗癌铂配合物SM54111在生理pH范围的溶液中稳定.在pH 4.5时,以SM54111色谱峰面积计算,得到降解反应速率常数K＝0.133 h-1,半衰期t1/2＝5.6 h.降解产物为母体化合物PtO键水解断裂的单齿水杨酸-Pt配合物,同时观察到Pt配合物的新裂解方式,可以经过亲柱攻击和重排反应同时脱去2个中性分子(C2H7N和H2),并证实其电离程度强烈依赖于电离原条件.该结果可为研究SM54111的药代动力学和药理学提供方法和参考.     

Conformational Dynamics of DNA G-Quadruplex in Solution Studied by Kinetic Capillary Electrophoresis Coupled On-line with Mass Spectrometry

Invited for this months cover is the group of Prof. Maxim V. Berezovski. The cover picture shows the two-dimensional separation of unfolded (green) and folded (red) forms of G-quadruplex (GQ) DNA. The first dimension is kinetic capillary electrophoresis (KCE) separation of unfolded and folded DNA with different K⁺ concentrations in solution; the second dimension is ion mobility mass spectrometry separation of DNA conformers in the gas phase. DNA folding into a compact GQ structure is mediated by K⁺ ions. For more details, see the Full Paper on p. 58 ff.     

Hadamard Transform Time‐of‐Flight Mass Spectrometry: More Signal,More of the Time

Hadamard transform time‐of‐flight mass spectrometry (HT‐TOF MS) is a type of mass analysis that was developed to couple continuous ion sources to the inherently pulsed nature of time‐of‐flight measurements. Unlike conventional TOF MS, the Hadamard transform method offers a duty cycle of 50 %, with the possibility of extending it to 100 %. Because it is a multiplexing technique, the attainable signal‐to‐noise ratio (SNR) is also significantly higher than that of conventional TOF MS. This review covers the basic principles behind HT‐TOF MS. We illustrate, through examples, the source of the high‐duty cycle and the increase in SNR. These features translate to a mass spectral storage rate that is the fastest among similar instruments, which enables its use as a detector for high‐speed separations.     

毛细管区带电泳监测牛胰岛素的去折叠过程

用毛细管区带电泳监测了二硫苏糖醇作用下二硫键还原引起的牛胰岛素去折叠全过程,同时用离线的基质辅助激光解吸／电离飞行时间的质谱配合确证。从毛细管电泳谱图能直接观察胰岛素去折叠过程中发生的变化,获得蛋白质去折叠信息。结果表明,毛细管区带电泳作为监测蛋白质构象变化的一种有效手段,方法简便、快速、灵敏度高、样品消耗量少。     

Capillary Electrophoresis Mass Spectrometry: Developments and Applications for Enantioselective Analysis from 2011–2020

It is now more than 25 years since the first report of enantioselective analysis by capillary electrophoresis-mass spectrometry (CE-MS) appeared. This article reviews the power of chiral CE-MS in resolving issues on the use of chiral selector incompatibility with MS and poor detectability encountered for chiral compounds by UV detection. The review begins with the general principles, requirements, and critical aspects of chiral CE-MS instrumentation. Next, the review provides a survey of MS-compatible chiral selectors (CSs) reported during the past decade, and the key achievements encountered in the time period using these CSs. Within the context of the strategies used to combine CE and MS, special attention is paid to the approaches that feature partial filling technique, counter-migration techniques, and direct use of CS, such as molecular micelles. In particular, the development and application of moving and fixed CS for EKC-MS, MEKC-MS, and CEC-MS demonstrate how various chiral compounds analyses were solved in a simple and elegant way during the 2010–2020 review period. The most noteworthy applications in the determination of chiral compounds are critically examined. The operating analytical conditions are detailed in the Tables, and the authors provide commentary on future trends of chiral separations by CE-MS.     

Study of the Transient Reactive Pd(IV) Intermediate in the Pd(OAc)2‐Catalyzed Oxidative Coupling Reaction System by Electrospray Ionization Tandem Mass Spectrometry

Pd‐catalyzed oxidative coupling reaction was of great importance in the aromatic C? H activation and the formation of new C? O and C? C bonds. Sanford has pioneered practical, directed C? H activation reactions employing Pd(OAc)₂ as catalyst since 2004. However, until now, the speculated reactive Pd(IV) transient intermediates in these reactions have not been isolated or directly detected from reaction solution. Electrospray ionization tandem mass spectrometry (ESI‐MS/MS) was used to intercept and characterize the reactive Pd(IV) transient intermediates in the solutions of Pd(OAc)₂‐catalyzed oxidative coupling reactions. In this study, the Pd(IV) transient intermediates were detected from the solution of Pd(OAc)₂‐catalyzed oxidative coupling reactions by ESI‐MS and the MS/MS of the intercepted Pd(IV) transient intermediate in reaction system was the same with the synthesized authentic Pd(IV) complex. Our ESI‐MS(/MS) studies confirmed the presence of Pd(IV) reaction transient intermediates. Most interestingly, the MS/MS of Pd(IV) transient intermediates showed the reductive elimination reactivity to Pd(II) complexes with new C? O bond formation into product in gas phase, which was consistent with the proposed reactivity of the Pd(IV) transient intermediates in solution.     

超声萃取/气相色谱-串联质谱法同时测定纺织品中6种禁用有机磷阻燃剂

以丙酮为萃取溶剂,建立了超声萃取/气相色谱-串联质谱同时测定纺织品中6种禁用有机磷阻燃剂的分析方法.6种禁用有机磷阻燃剂三-(1-氮杂环丙基)氧化膦( TEPA)、三-(2-氯乙基)磷酸酯(TCEP)、三-(2,3-二氯丙基)磷酸酯(TDCP)、二-(2,3-二溴丙基)磷酸酯(DDBPP)、三-(邻甲苯基)磷酸酯(TO...