液质联用中接口离子化新技术

液相色谱-质谱联用(简称液质联用,LC-MS)将色谱的高分离效能与质谱强大的结构测定功能结合,不仅实现了对复杂混合物更准确的定性定量分析,而且简化了样品的前处理过程,使样品分析更简便,在药物分析、食品与环境分析以及生物样品检测等众多领域得到了广泛的应用。作为LC-MS的核心组成部分,液质接口的作用是将LC的液体引入,发生电离,并将生成的离子传输进MS。因此,接口离子化技术的改进直接影响了LC-MS的发展和应用。为了获得更高的灵敏度和更广泛的适用性,研究人员一直致力于离子化技术的研究,以促进分析物的解吸,提高其电离和传输效率,减少基质效应的干扰。本文针对近年来LC-MS接口离子化技术的改进和发展,从离子化原理出发,对接口离子源的构造、影响电离的因素、以及相关的应用进行综述,探讨其优缺点,并对LC-MS接口离子化技术的发展趋势进行了展望。     

Improving Liquid Chromatography-Mass Spectrometry Sensitivity Using a Subambient Pressure Ionization with Nanoelectrospray (SPIN) Interface

In this work, the subambient pressure ionization with nanoelectrospray (SPIN) ion source and interface, which operates at ~15–30 Torr, is demonstrated to be compatible with gradient reversed-phase liquid chromatography-MS applications, exemplified here with the analysis of complex samples (a protein tryptic digest and a whole cell lysate). A low liquid chromatographic flow rate (100–400 nL/min) allowed stable electrospray to be established while avoiding electrical breakdown. Efforts to increase the operating pressure of the SPIN source relative to previously reported designs prevented solvent freezing and enhanced charged cluster/droplet desolvation. A 5- to 12-fold improvement in sensitivity relative to a conventional atmospheric pressure nanoelectrospray ionization (ESI) source was obtained for detected peptides.     

高效液相色谱-电喷雾串联质谱法确证海洋微生物产生的新环肽的连接顺序

报道了采用高效液相色谱一电喷雾串联质谱技术测定由海洋内生真菌产生的2个新环五肽cyelo（Phe-Leu-Leu-Leu-Ile）和cyclo（Phe-Val-Leu-Leu-Leu）,串联质谱实验提供了丰富的结构信息,确证了环肽的氨基酸的种类和连接顺序。这种简单、快速、可靠的分析方法在对未知样品中环肽成分的检测中具有广阔的应用前景。     

High Sensitivity Analysis of Nanoliter Volumes of Volatile and Nonvolatile Compounds using Matrix Assisted Ionization (MAI) Mass Spectrometry

First results are reported using a simple, fast, and reproducible matrix-assisted ionization (MAI) sample introduction method that provides substantial improvements relative to previously published MAI methods. The sensitivity of the new MAI methods, which requires no laser, high voltage, or nebulizing gas, is comparable to those reported for MALDI-TOF and n-ESI. High resolution full acquisition mass spectra having low chemical background are acquired from low nanoliters of solution using only a few femtomoles of analyte. The limit-of-detection for angiotensin II is less than 50 amol on an Orbitrap Exactive mass spectrometer. Analysis of peptides, including a bovine serum albumin digest, and drugs, including drugs in urine without a purification step, are reported using a 1 μL zero dead volume syringe in which only the analyte solution wetting the walls of the syringe needle is used in the analysis.

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反相高效液相色谱柱前衍生荧光检测法测定游离多胺

合成新型荧光试剂1,2-苯并-3,4-二氢咔唑-9-异丙基氯甲酸酯(BCIC)作为柱前衍生化试剂,在Eclipse XDB-C8色谱柱上,通过梯度洗脱对5种多胺进行了分离和在线质谱定性。在乙腈中,以硼酸钠缓冲液(pH9)为催化剂,40℃下衍生反应10min后获得稳定的荧光产物。激发和发射波长分别为λex=333nm,λem=390nm。采用大气压化学电离源(APCI)正离子模式,实现了人尿中游离多胺的定性及定量测定。多胺的线性相关系数大于0.9996,检出限为5.3～9.9fmol。     

Carbonation and Other Super Saturated Gases as Solution Modifiers for Improved Sensitivity in Solvent Assisted Ionization Inlet (SAII) and ESI

Solvent Assisted Ionization Inlet (SAII) produces ions in a heated inlet to a mass spectrometer from aqueous and aqueous/organic solutions with high sensitivity. However, the use of acid modifiers, which typically aids electrospray ionization, generally results in ion suppression in SAII. Here we demonstrate that the use of carbonation and other super-saturated gases as solution modifiers increases analyte ion abundance and reduces metal cation adduction in SAII. Carbonation is also found to enhance electrospray ionization. The mechanistic and practical utility of carbonation in mass spectrometry is addressed.      

溶剂诱导相变萃取法用于高效液相色谱-质谱分析的血浆样品前处理

在匀相的乙腈-水体系中添加一种疏水但与乙腈互溶的有机溶剂(如氯仿), 能诱导乙腈-水体系分相, 基于此现象建立了一种血浆样品处理方法溶剂诱导相变萃取(SIPTE). 与传统的液-液萃取法相比, 该法最大的优势为新形成的有机相为乙腈(仅含少量氯仿), 与常用的反相C₁₈柱兼容, 能直接进行高效液相色谱-质谱分析. 此外, 通过减少乙腈及氯仿的用量还可实现样品的自动浓缩. 本文通过测定血浆中尼群地平, 验证了该方法的有效性. 使用反相C₁₈柱, 以V(乙腈)∶V(水)=70∶30(含20 mmol/L甲酸铵)为流动相, 尼莫地平为内标, ESI正离子模式下选择离子监测(SIM)测定了血浆中尼群地平的浓度. 实验所得的线性、精密度和准确度结果良好, 表明所建立的方法灵敏、准确、简单、快速, 可用于药物代谢动力学研究.     

Simultaneous Determination of Artesunate and Dihydroartemisinin Concentrations in Human Plasma by High Performance Liquid Chromatography-Mass Spectrometry with Electro-Spray Ionization

An analytical procedure was developed/validated for the quantification of artesunate (ARTS) and a metabolite, dihydroartemisinin (DHA), in human plasma. Plasma samples were processed by solid-phase extraction and analyzed by LC-MS. The detector response was specific and linear for ARTS and DHA concentrations in the range of 5–1000 ng/mL. Intra-/inter-day precision/accuracy were determined to be within the acceptance criteria for assay validation guidelines. The analytes were stable under various processing/handling conditions. The ARTS/DHA concentrations were readily measured in plasma samples up to 8 hrs after an oral administration of an ARTS formulation in humans, suggesting that the assay is practically useful.     

血清脂质组学研究中多重离子化液相色谱-质谱方法的比较

系统地比较了3种常用的离子化技术电喷雾电离(ESI)、大气压化学电离(APCI)、大气压光致电离(APPI)对脂类化合物的离子化效率、检测灵敏度和覆盖范围,以探讨多重离子化液相色谱-质谱(LC-MS)方法在血清脂质组学研究中的适用性.血清样本经甲基叔丁基醚萃取后,采用Ascentiss Express C8 色谱柱(150 mm×2.1 mm, 2.7 μm)和二元线性梯度洗脱分离,流动相(A)为乙腈-水(3∶2, V/V, 含0.1%甲酸, 10 mmol/L甲酸铵),B为异丙醇-乙腈(9∶1, V/V, 含0.1%甲酸,10 mmol/L甲酸铵),分别采用ESI、APCI和APPI离子源正、负离子模式进行质谱检测.结果表明,ESI离子源对脂肪酸类、甘油脂类、甘油磷脂类化合物、鞘磷脂类化合物的离子化效率最高,对异戊烯醇脂类化合物的离子化效率与APPI离子源相当,APPI离子源对胆固醇(酯)类化合物的检测灵敏度最高,APCI离子源对各类化合物的检测灵敏度均低于ESI或APPI离子源;采用ESI和APPI离子源相结合的LC-MS脂质组学分析方法可以提高分析方法的整体灵敏度和血清中脂类信息检测的完整性.     

三氯新降解产物的液相色谱-质谱分析

三氯新(triclosan,又名三氯生、三氯洁等)是一种高效、广谱抗微生物剂,已广泛应用于化妆品、儿童玩具、厨房用品等方面。三氯新对人体并没有危害,但由于其结构和目前已知的一些有害化合物如二结构相似,所以对三氯新在催化加氢降解过程中的结构变化情况进行分析十分必要。本文利用高效液相色谱 质谱联用技术对三氯新的催化加氢降解产物进行了分析,确定了产物的类型,并推导出其中一个产物的结构,为进一步安全、合理地使用三氯新提供了一些有益的参考。1　实验部分　　仪器和试剂:Waters2690高效液相色谱仪,Waters996二极管阵列检测器…     

加速溶剂萃取/超高压液相色谱-质谱联用对土壤中甲胺磷的测定研究

建立了加速溶剂萃取/超高压液相色谱-质谱联用测定土壤中甲胺磷的方法。确定最佳萃取条件为:萃取溶剂为乙腈,萃取温度80℃,静态萃取时间10 min,循环2次。萃取液经旋转蒸发仪浓缩后,进超高压液相色谱-质谱分析,外标法定量,质谱定性。结果表明,甲胺磷的线性范围为3.15~1 050μg/L,相关系数为0.999 1。低、中、高3个加标水平下甲胺磷的平均回收率为72%~82%,相对标准偏差为5.8%~8.6%,检出限为0.05μg/kg。该方法具有良好的分离效果、较宽的线性范围和较高的灵敏度,可用于实际样品检测。     

高效液相色谱-质谱联用分析无患子中的表面活性物质

 应用高效液相色谱和大气压电离质谱联用技术 ,分离分析了无患子果皮中的表面活性成分。根据质谱结果确定其相对分子质量 ,根据源内的碰撞诱导解离 (CID)技术产生的碎片初步推测表面活性物质的结构 ,发现了数个未见文献报道的组分。     

高效液相色谱-质谱法对水果中矮壮素的检测

建立了水果中矮壮素残留的高效液相色谱-电喷雾质谱(LC-ESI MS)检测方法.采用甲醇-水-乙酸溶液提取试样中的矮壮素残留,离心后,取上清液过SCX阳离子交换固相萃取小柱,LC-ESI MS测定,以保留时间和特征离子定性,外标法定量.在优化色谱条件下,矮壮素得到很好的分离,在0.03 ～10 mg/L范围内线性良好,线性相关系数(R2)为0.999 1,方法的定量下限可达0.02 mg/kg.     

内墙涂料中烷基酚聚氧乙烯醚的高效液相色谱-质谱测定

建立了高效液相色谱-质谱法(HPLC-MS)测定内墙涂料中烷基酚聚氧乙烯醚(辛基酚聚氧乙烯醚和壬基酚聚氧乙烯醚)含量的方法。样品经甲醇超声提取,采用Agilent Eclipse Plus C18柱(4.6 mm×100 mm,3.5μm),以5 mmol/L乙酸铵溶液-甲醇作为流动相进行梯度洗脱分离,柱温35℃,流速0.3 m L·min-1,进样量5μL。质谱采用选择离子(SIM)方式进行检测,电喷雾离子源(ESI),正离子模式,基质匹配标准溶液定量,以A和B两种内墙涂料为代表进行加标回收实验。结果表明,辛基酚聚氧乙烯醚(OPEO)和壬基酚聚氧乙烯醚(NPEO)在0.1~5.0 mg/L浓度范围内线性关系良好(r0.99),回收率为83.8%~114.5%,相对标准偏差为1.3%~9.8%,定量下限为4.0~5.5 mg/kg。该方法操作简便、耗时短、有机试剂用量少、灵敏度高、稳定性好,应用于日常检测可大大降低检测成本,缩短检测周期,具有实际应用价值。     

高效液相色谱/电喷雾质谱法测定血浆中曲美他嗪浓度

建立了高效液相色谱/电喷雾质谱法(HPLC/ESI-MS)测定人血浆中曲美他嗪浓度。以利多卡因为内标,样品经甲醇沉淀蛋白,取上清液用三氟乙酸酸化后,50℃真空离心,浓缩至干,流动相溶解后进样。色谱柱:Waters Xterra MSC18(150mm×4.6mm,5μm),柱温:40℃,流动相:pH2.00的三氟乙酸溶液-甲醇(60∶40,V/V),流速:0.6mL/min;电喷雾离子源,四级杆质谱检测器,选择离子监控模式,检测离子的质核比分别是235(利多卡因)和267(曲美他嗪)。曲美他嗪的线性范围为2.5~100μg/L,检出限2.5μg/L;日间、日内相对标准差均小于7%;相对回收率96.45%~103.03%,提取回收率72.45%~80.47%。     

加速溶剂萃取―气相色谱―质谱法测定土壤中酞酸酯类有机物

建立了土壤中酞酸酯类的加速溶剂萃取（ASE）―气相色谱―质谱（GC-MS）测定方法。通过对萃取溶剂和层析柱的优化选择,得出优化萃取条件。同时,实验过程中采用铬酸洗液对实验器皿进行清洗,有效控制了环境中酞酸酯对样品的污染。该优化方法结果显示：平均加标回收率为89.5%～106.0%,相对标准偏差为1.5%～5.8%,检出...     

基于超高效液相色谱-质谱红花药材指纹图谱的建立

以红花为研究对象，建立超高效液相色谱-质谱（UPLC-MS）指纹图谱分析方法，为红花药材质量鉴别提供借鉴.通过考察检测波长、梯度洗脱条件、提取溶剂、提取方法等因素，在最优条件下对20个产地的红花样品进行分离分析.色谱柱：Thermo Hypersil Gold C₁₈，100 mm×2.1 mm，1.9 μm，流动相：0.1%甲酸水溶液（A）-乙腈（B）；流速：0.3 mL/min；柱温：30℃；检测波长：270 nm；进样量：2 μL，质谱条件：鞘气流速：45 arb，辅助气流速15 arb，雾化电压：3.3 KV，离子传输管温度：350℃，辅助气加热温度：400℃.试验结果：共确定了67个共有峰，通过UPLC-MS指认了其中11个共有峰，对20批不同产地的红花药材指纹图谱进行了相似度评价，其相似度在0.687~0.971之间.建立的UPLC-MS指纹图谱可为红花药材的质量控制提供参考依据.     

液相色谱-质谱法对饮用水中六价铬的测定

建立了液相色谱分离、电喷雾质谱测定饮用水中六价铬的方法.水样经微孔滤膜过滤后直接进样,以乙腈-1.5 mmol/L四丁基氢氧化铵水溶液为流动相,Xterra~(TM) MS C_(18)色谱柱分离六价铬,使用单四极杆质谱,选择离子模式检测,监测离子为m/z 118、117、101、85,其中117为定量离子.Cr(Ⅵ)的线性范围为1.0 ～100.0 μg/L,方法定量下限为1 μg/L.在空白水样中分别添加1.0、2.0、10.0 μg/L的六价铬,测得平均回收率(n=5)依次为91%、94%、97%,相对标准偏差分别为12.2%、7.4%、3.5%.测定了42个饮用水样品,其中17批检出六价铬,检出量为1.2 ～15.4 μg/L.     

Rapid Determination of 10 Parabens in Spices by High Performance Liquid Chromatography-Mass Spectrometry

An ultra-high-performance liquid chromatography with electrospray ionization tandem mass spectrometry (UHPLC-ESI-MS/MS) method was developed for determination of ten parabens (methyl-, ethyl-, propyl-, isopropyl-, butyl-, isobutyl-, amyl-, isoamyl-, hexyl-, and heptyl-parabens) in spices. After simple preparation, the extract was injected directly into the UHPLC-MS/MS system. Parabens were separated on an Acquity UPLC BEH C18 column using gradient elution programming and detected by the tandem quadrupole mass spectrometer operating in a negative-ion electrospray-ionization (-ESI) mode. The total run time of liquid chromatography was 13 min. Linear calibration curves of 10 parabens were obtained in the range of 0.10–20.00 ng/mL under optimum conditions (r > 0.9990). The limits of detection (LOD) and the limits of quantification (LOQ) were in the range between 0.01–0.08 ng/g and 0.03–0.20 ng/g, respectively. Intra-day precision and inter-day precision were 1.04%–2.13% and 1.03%–3.16%, respectively. Recoveries were between 89.41% and 99.30%. This proposed method was successfully applied in 11 kinds of spices (38 brands). In these samples, combinations of parabens appeared more frequently than we anticipated, and 63.16% of them contained more than one paraben. As a result, it was necessary to simultaneously test for 10 parabens in spices.     

A Mechanism for Ionization of Nonvolatile Compounds in Mass Spectrometry: Considerations from MALDI and Inlet Ionization

Mechanistic arguments relative to matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) address observations that predominately singly charged ions are detected. However, recently a matrix assisted laser ablation method, laserspray ionization (LSI), was introduced that can use the same sample preparation and laser as MALDI, but produce highly charged ions from proteins. In MALDI, ions are generated from neutral molecules by the photon energy provided to a matrix, while in LSI ions are produced inside a heated inlet tube linking atmospheric pressure and the first vacuum region of the mass spectrometer. Some LSI matrices also produce highly charged ions with MALDI ion sources operated at intermediate pressure or high vacuum. The operational similarity of LSI to MALDI, and the large difference in charge states observed by these methods, provides information of fundamental importance to proposed ionization mechanisms for LSI and MALDI. Here, we present data suggesting that the prompt and delayed ionization reported for vacuum MALDI are both fast processes relative to producing highly charged ions by LSI. The energy supplied to produce these charged clusters/droplets as well as their size and time available for desolvation are determining factors in the charge states of the ions observed. Further, charged droplets/clusters may be a common link for ionization of nonvolatile compounds by a variety of MS ionization methods, including MALDI and LSI.