Mannose7 Glycan Isomer Characterization by IMS-MS/MS Analysis

The isomers of the Man₇GlcNAc₂ glycan obtained from bovine ribonuclease B have been characterized by ion mobility spectrometry-tandem mass spectrometry (IMS-MS/MS). In these experiments, [Man7 + 2Na]²⁺ precursors having different mobilities are selected by ion mobility spectrometry and analyzed by MS/MS techniques in an ion trap. The fragmentation spectra obtained for various precursor ions are specific, suggesting the isolation or enrichment of different glycan isomers. One fragment ion with a mass-to-charge ratio (m/z) of 903.8 is found to correspond to the loss of an internal mannose residue of a specific isomer. Extracted fragment ion drift time distributions (XFIDTDs) yield distinctive precursor ion drift time profiles indicating the existence of four separate isomers as proposed previously.     

脑啡肽的固相合成与LC-MS/MS分离鉴定

多肽在生命过程中扮演着重要的角色,对其生理生化功能的研究与应用,离不开对单一多肽物质的需求,而化学合成法是获取目标多肽的最有效方法之一。对合成产物的分离与鉴定,是优化合成条件,以得到高产率的重要保证。以两种内源性神经肽亮氨酸脑啡肽和甲硫氨酸脑啡肽为模型,利用Fmoc固相多肽合成策略对其进行合成,并建立了HPLC-ESI-MS/MS新方法用于所制备的亮氨酸脑啡肽和甲硫氨酸脑啡肽的分离与结构鉴定。研究结果显示,主要合成产物均为目标多肽,副产物主要包括C端丢失1个氨基酸所形成的四肽,以及由于甲硫氨酸残基氧化而形成的含甲硫氨酸亚砜的多肽。该研究为高效合成含敏感氨基酸的生理活性多肽提供了新信息。     

Structural Feature Ions for Distinguishing N- and O-Linked Glycan Isomers by LC-ESI-IT MS/MS

Glycomics is the comprehensive study of glycan expression in an organism, cell, or tissue that relies on effective analytical technologies to understand glycan structure–function relationships. Owing to the macro- and micro-heterogeneity of oligosaccharides, detailed structure characterization has required an orthogonal approach, such as a combination of specific exoglycosidase digestions, LC-MS/MS, and the development of bioinformatic resources to comprehensively profile a complex biological sample. Liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS/MS) has emerged as a key tool in the structural analysis of oligosaccharides because of its high sensitivity, resolution, and robustness. Here, we present a strategy that uses LC-ESI-MS/MS to characterize over 200 N- and O-glycans from human saliva glycoproteins, complemented by sequential exoglycosidase treatment, to further verify the annotated glycan structures. Fragment-specific substructure diagnostic ions were collated from an extensive screen of the literature available on the detailed structural characterization of oligosaccharides and, together with other specific glycan structure feature ions derived from cross-ring and glycosidic-linkage fragmentation, were used to characterize the glycans and differentiate isomers. The availability of such annotated mass spectrometric fragmentation spectral libraries of glycan structures, together with such substructure diagnostic ions, will be key inputs for the future development of the automated elucidation of oligosaccharide structures from MS/MS data.

Chromatographic alignment of LC-MS and LC-MS/MS datasets by genetic algorithm feature extraction

Liquid chromatography-mass spectrometry (LC-MS) datasets can be compared or combined following chromatographic alignment. Here we describe a simple solution to the specific problem of aligning one LC-MS dataset and one LC-MS/MS dataset, acquired on separate instruments from an enzymatic digest of a protein mixture, using feature extraction and a genetic algorithm. First, the LC-MS dataset is searched within a few ppm of the calculated theoretical masses of peptides confidently identified by LC-MS/MS. A piecewise linear function is then fitted to these matched peptides using a genetic algorithm with a fitness function that is insensitive to incorrect matches but sufficiently flexible to adapt to the discrete shifts common when comparing LC datasets. We demonstrate the utility of this method by aligning ion trap LC-MS/MS data with accurate LC-MS data from an FTICR mass spectrometer and show how hybrid datasets can improve peptide and protein identification by combining the speed of the ion trap with the mass accuracy of the FTICR, similar to using a hybrid ion trap-FTICR instrument. We also show that the high resolving power of FTICR can improve precision and linear dynamic range in quantitative proteomics. The alignment software, msalign, is freely available as open source.     

液相色谱串联质谱测定蔬菜中残留的唑菌胺酯

唑菌胺酯(pyraclostrobin)俗称百泰,德国巴斯夫公司于1993年开发的兼具吡唑结构的甲氧基丙烯酯酯类菌剂~([1]),主要用于防治小麦、水稻、花生、葡萄、蔬菜、香蕉、 柠檬、咖啡、果树、核桃、蔬菜、茶树、烟草和观赏植物、草坪及其他大田作物上由子囊菌纲、担子菌纲、半知菌类和卵菌纲真菌引起的作物病害~([2]).     

非衍生化/液相色谱-串联质谱法测定食品中的二硫代氨基甲酸酯类农药残留

通过优化质谱、液相色谱和萃取缓冲液等条件,建立了一种简单、快速、灵敏测定食品中二硫代氨基甲酸酯的方法。在优化条件下,代森锌(EBDC)、丙森锌(PBDC)的线性范围为2～100μg/L,相关系数均不小于0.997。在花椰菜、萝卜和豌豆中EBDC和PBDC的检出限(S/N>3)为2μg/kg;萝卜和豌豆中EB-DC和PBDC的定量下限(S/N>10)为10μg/kg,而花椰菜中EBDC和PBDC的定量下限(S/N>10)为15μg/kg。在花椰菜、萝卜和豌豆基质中加标5～100μg/kg的EBDC和PBDC时,测定加标回收率为83%～96%,相对标准偏差为4.4%～10.5%,方法可满足定量分析的要求。     

Multi-mycotoxin analysis of maize silage by LC-MS/MS

This paper describes a method for determination of 27 mycotoxins and other secondary metabolites in maize silage. The method focuses on analytes which are known to be produced by common maize and maize-silage contaminants. A simple pH-buffered sample extraction was developed on the basis of a very fast and simple method for analysis of multiple pesticide residues in food known as QuEChERS. The buffering effectively ensured a stable pH in samples of both well-ensiled maize (pH < 4) and of hot spots with fungal infection (pH > 7). No further clean-up was performed before analysis using liquid chromatography–tandem mass spectrometry. The method was successfully validated for determination of eight analytes qualitatively and 19 quantitatively. Matrix-matched calibration standards were used giving recoveries ranging from 37% to 201% with the majority between 60% and 115%. Repeatability (5–27% RSD_r) and intra-laboratory reproducibility (7–35% RSD_IR) was determined. The limit of detection (LOD) for the quantitatively validated analytes ranged from 1 to 739 μg kg⁻¹. Validation results for citrinin, fumonisin B₁ and fumonisin B₂ were unsatisfying. The method was applied to 20 selected silage samples and alternariol monomethyl ether, andrastin A, alternariol, citreoisocoumarin, deoxynivalenol, enniatin B, fumigaclavine A, gliotoxin, marcfortine A and B, mycophenolic acid, nivalenol, roquefortine A and C and zearalenone were detected.     

牛奶中链霉素与双氢链霉素残留检测的液相色谱-串联质谱法研究

链霉素(streptomycin)是从放线菌属灰链丝菌培养液中提取的一种氨基糖苷类抗生素,兽医临床上常用于预防和治疗革兰氏阴性菌和结核杆菌等引起的感染.由于其抗菌谱广,而且价格低廉,因此在奶牛养殖业中常被大量应用于治疗奶牛乳腺炎等.     

甲卡西酮的LC-MS/MS定性定量分析方法

建立了LC-MS/MS法定性定量分析甲卡西酮。采用三重串联四极杆液质联用仪(LC/QQQ),AgilentZorbax Eclipse Plus C18色谱柱(100 mm×2.1 mm,1.8μm),流动相为0.1%甲酸-乙腈,梯度洗脱,流速为0.3mL/min。质谱应用ESI源、正离子模式、多反应监测(MRM)方式。在0.1～10 000 ng/mL质量浓度范围内线性关系良好,r2=0.999 8,日内与日间保留时间和峰面积的相对标准偏差不大于5.28%,检出限为0.04 ng/mL,回收率为95.6%～100.7%。该方法适用于甲卡西酮的定性、定量分析。     

禽肉中己烯雌酚的LC-MS/MS测定

20世纪70年代人们发现己烯雌酚有蛋白同化作用,许多养殖户用其促进家畜、家禽的发育,达到提高经济效益的目的.     

液相色谱-串联质谱法测定人血浆中的维拉帕米

维拉帕米（Verapamil,Ver）是第一代钙离子拮抗剂,临床上主要用于心律失常、心绞痛和高血压的治疗。有关生物样品中Ver的分析方法报道较多,主要有高效液相色谱（HPLC）-紫外检测法、HPLC-荧光检测法和高效毛细管电泳法,但色谱分析时间均大于8min。最近有文献报道采用液相色谱-串联质谱法（LC—MS／MS）测定人血浆中Ver及其活性代谢物去甲维拉帕米的对映异构体。本文旨在建立一种专属、快速、灵敏的LC—MS／MS用于测定人血浆中的Ver,以研究该药在体内的药代动力学特点。     

LC-MS/MS法定量测定人血浆中的氯氮平

建立了人血浆中氯氮平的固相萃取及LC-MS/MS定量检测方法.血浆中的氯氮平用固相萃取柱(Bond Elut Certify)萃取,采用Waters AtlantisTMd C18色谱柱,电喷雾离子源,正离子检测,多反应监测方式进行定量分析,SKF525a作为内标.对氯氮平的定量下限为100 ng/mL,氯氮平质量浓度...     

高效液相色谱-串联质谱法测定小鼠组织中的新型抗心力衰竭化合物AF-HF001

建立了基于高效液相色谱-质谱联用技术的新型抗心力衰竭化合物AF-HF001在小鼠组织中的测定方法,并考察了其在小鼠体内的组织分布。采用液-液萃取对样品进行预处理,以Thermo Hypersil Gold C18色谱柱进行分离,流动相为乙腈-0.1%甲酸水溶液,梯度洗脱,采用选择性反应监测(SRM)正离子模式检测分析物。小鼠组织中AF-HF001含量在0.5~10μg/mL范围内线性关系良好(r>0.996),在加标量为1.5,4,10μg/mL的组织样品中,提取回收率大于58%,基质效应在100.38%~109.99%之间,日内和日间精密度RSD均小于15%。该方法为AF-HF001的体内分布研究及进一步药物研发提供了依据。初步结果表明,该化合物能够迅速到达心脏并迅速代谢,主要分布在肝脏组织中,其他组织中分布较少。     

液相色谱串联质谱法(LC-MS/MS)分析宠物食品中三聚氰胺

三聚氰胺(melamine)为白色或无色结晶,通常用于塑料制品中合成树脂的生产中,高温和酸性条件下能引起三聚氰胺转移到食品中.三嗪类农药环丙氨嗪(cyromazine)在极端的pH条件下或者光降解的条件下也能生成三聚氰胺.     

液相色谱-串联质谱法快速测定奶粉中的双氰胺

建立了奶粉中双氰胺的高效液相色谱-串联质谱快速测定方法。实验优化了前处理条件、液相色谱条件和质谱参数。样品经水提取,乙腈分次沉淀蛋白后,采用亲水高效液相色谱柱分离,流动相为乙腈(含0.2%甲酸)-0.1%甲酸(含10 mmol/L甲酸铵)(体积比95∶5),流速0.3 mL/min。采用正离子模式的电喷雾质谱检测,多反应(MRM)选择离子监测,检测离子对为m/z 85→68和m/z 85→43,检测周期为5 min。结果显示,双氰胺在0.2～100μg/L范围内线性良好,相关系数为0.999 8。双氰胺的检出限为0.1μg/L,方法的定量下限为5μg/kg。低、中、高3个加标水平下的平均回收率为79%～83%,相对标准偏差为2.7%～6.5%。方法简便快速、准确可靠,已用于奶粉中双氰胺的检测。     

粮谷中双苯唑菌醇残留量的液相色谱-质谱/质谱检测

建立了糙米、玉米、大麦、小麦、荞麦、大米、高粱、燕麦中双苯唑菌醇残留量的液相色谱-质谱/质谱测定方法.样品经乙腈提取,氨基(NH2)固相萃取柱净化,液相色谱-质谱/质谱仪测定,外标法定量.方法的定量下限为0.025 mg/kg,粮谷样品在0.025、0.050、0.500 mg/kg添加水平的平均回收率为 79% ～92%,相对标准偏差为4.8% ～10.8%,可以满足进出口谷物中双苯唑菌醇残留量的检测需要.     

Analysis of Processing Effects on Glucosinolate Profiles in Red Cabbage by LC-MS/MS in Multiple Reaction Monitoring Mode

Red cabbage (Brassica oleracea L. var. capitata) continues to receive increasing attention on its health-promoting properties because of its high glucosinolate content. Glucosinolates are an unstable active substance; however, there are few studies on their changes in different cooking processes. In this study, we investigated the effects of processing methods (boiling, steaming, microwave heating, frying, stir-frying) and boiling time on glucosinolates in red cabbage. Ten glucosinolates, including 4-methoxyglucobrassicin, neoglucobrassicin, glucoalyssin, glucobrassicin, glucoraphanin, glucoiberin, progoitrin, gluconapin and sinigrin, in red cabbage were detected. Decreases of 32.36%, 24.83%, 25.27%, 81.11% and 84.29% for total glucosinolates were observed after boiling, microwaving, steaming, frying and stir-frying. Indole glucosinolates were more efficiently lost compared to aliphatic glucosinolates after boiling, while microwaving, steaming, frying and stir-frying also resulted in a greater reduction in indole glucosinolates than aliphatic glucosinolates. Glucoalyssin, glucoerucin and sinigrin were more thermal sensitive than other glucosinolates. It was confirmed that microwaving and steaming retained higher levels of glucosinolates than other methods and may be better for cooking red cabbage.     

液相色谱-串联质谱法测定食品中甲基磺草酮

食品用乙腈-水(3+1)溶液进行提取,经凝胶色谱、固相萃取柱净化后,用液相色谱-串联质谱法进行测定和确证,外标法定量。色谱分离用甲醇和甲酸-水(0.1+99.9)溶液以不同体积比混合为流动相梯度洗脱,采用负离子模式电喷雾离子源在多反应监测模式下进行检测。甲基磺草酮的质量浓度在0.01~0.2 mg·L-1范围内与其峰面积呈线性关系。以4种食品样品为基体,加入3种浓度水平的甲基磺草酮标准做回收试验,测得回收率在73.2%~100.6%之间;测定值的相对标准偏差(n=10)在4.1%~11%之间。     

Determination of chloroacetanilides, triazines and phenylureas and some of their metabolites in soils by pressurised liquid extraction, GC-MS/MS, LC-MS and LC-MS/MS

Pressurised liquid extraction (PLE) technique was used for the simultaneous extraction of phenylureas, triazines and chloroacetanilides and some of their metabolites from soils. Extractions were performed by mixing 15 g of dried soil with 30 mL of acetone under 100 atm at 50 degrees C, during 3 min and with three PLE cycles. Prior to the analysis of naturally contaminated soils, each of the five representative soil matrices used as blanks (of different depths) was spiked in triplicate with standards of each parent and degradation compound at about 10, 30 and 120 microg/kg. For each experiment, isoproturon-D6 and atrazine-D5 were used as surrogates. Analysis of phenylureas and metabolites of triazines and phenylureas was carried out by reversed phase liquid chromatography/mass spectrometry (LC-MS) and LC-MS/MS in the positive mode. Gas chromatography (GC)/ion trap mass spectrometry was used in the MS/MS mode for the parent triazines and chloroacetanilides. The average extraction recoveries were above 85%, except for didesmethyl-isoproturon, and quantification limits were between 0.5 and 5 microg/kg. The optimised multi-residue method was applied to soils and solids below the root zone, sampled from agricultural plots of a small French hydrogeological basin.     

液相色谱–串联质谱法测定水果及其制品中氯吡脲残留量

建立了液相色谱–三重四极杆串联质谱测定水果及其制品中氯吡脲的方法。样品经乙腈提取,氨基固相萃取小柱净化后,用ZORBAX Extend-C18柱(150 mm×2.1 mm,5μm)分离,以甲醇–水为流动相等度洗脱,采用多反应监测正离子模式检测,外标法定量。氯吡脲的质量浓度在4.0~200.0 ng/m L范围内线性良好,相关系数大于0.999,在5.0,10.0,20.0μg/kg 3个添加水平下,氯吡脲的平均加标回收率为86%~92%,测定结果的相对标准偏差为5.3%~7.6%(n=5),方法定量下限为2.0μg/kg。方法灵敏度高,操作简便,定量准确,可满足梨、柑桔、黄桃等水果及其罐头制品中氯吡脲残留的检测与确证需要。