Rapid analysis of fifteen sulfonamide residues in pork and fish samples by automated on-line solid phase extraction coupled to liquid chromatography–tandem mass spectrometry

The aim of this work was to develop an automated on-line solid phase extraction(SPE)with liquid chromatography-tandem mass spectrometry method for the detection of fifteen sulfonamides in pork and fish samples.Samples were extracted with 0.2%formic acid acetonitrile solution,purified by on-line SPE device with HLB column,then separated by XBridge C18 column,using 0.1%formic acid solution and acetonitrile as the mobile phase.Mass spectrometric data was acquired under multiple reaction monitoring(MRM)mode using positive ionization electrospray.Internal standard method was used in the quantification,good linear relationship was got in range of 0.1–100 ng/mL and correlation coefficient was higher than 0.9990.The limits of detection were in the range of 0.125–2.00g/kg and the limits of quantitation were in the range of 0.250–5.00g/kg.Recoveries of the method were in range of 78.3%–99.3%,relative standard deviation were lower than 10%.The method was simple,sensitivity,and could be used for routine supervision and analysis of fifteen sulfonamides in pork and fish.

Product Identification and Mass Spectrometric Analysis of n-Butane and i-Butane Pyrolysis at Low Pressure

The pyrolysis of n-butane and i-butane at low pressure was investigated from 823-1823 K in an electrically heated flow reactor using synchrotron vacuum ultraviolet photoionization mass spectrometry. More than 20 species, especially several radicals and isomers, were detected and identified from the measurements of photoionization efficiency （PIE） spectra. Based on the mass spectrometric analysis, the characteristics of n-butane and i-butane pyrolysis were discussed, which provided experimental evidences for the discussion of decomposition pathways of butane isomers. It is concluded that the isomeric structures of n-butane and i-butane have strong influence on their main decomposition pathways, and lead to dramatic differences in their mass spectra and PIE spectra such as the different dominant products and isomeric structures of butene products. Furthermore, compared with n-butane,i-butane can produce strong signals of benzene at low temperature in its pyrolysis due to the enhanced formation of benzene precursors like propargyl and C4 species, which provides experimental clues to explain the higher sooting tendencies of iso-alkanes than n-alkanes.

Mass Spectrometric Study of Clusters Produced by Laser Vaporization of Some Phosphates

The clusters generated by direct laser vaporization of KH2PO4 and Cu-3(PO4)(2) samples are studied by a TOF mass spectrometer. It is found that mainly the [K(KPO3)(n)]* cluster series is generated from KH2PO4 sample and it demonstrates obvious magic numbers, which are n=3, 6, 9, 12, 15. Direct laser vaporization of Cu-3(PO4)(2) sample produced [Cu(CuPO3)n]* cluster series as well as other series with the same building block of (CUPO3).

Chemical Selectivity of Laser Ion Source for on-Line Mass Separator

Thulium(Tm)atoms are resonantly ionized in a hot tube by stepwise excitations us-ing three dye lasers pumped by a series of copper vapor pulsed at a 10 kHz rate.The chemicalselectivity of the laser ion source is measured as a function of temperature of the tubes made ofTa,Nb-Zr and TaC.The chemical selectivity rises from 50 to 10000 with decreasing tube temp-erature and strongly depends on the tube material.A chemical selectivity of about 10000 withhigh efficiencies is obtained with the Nb-Zr and TaC tubes.Such a laser ion source can be usedin on-line mass separator to obtain isobarically pure ion beams.

High Precision Thermal Ionization Mass Spectrometric Dating of Corals and Its Application to Paleo-Environmental Study

Global change has become a hot spot in Quaternary geology, and high\|precision, high\|sensitivity dating is also an urgent problem which needs to be solved. This paper presents some achievements in U\|series dating of marine corals by thermal ionization mass spectrometry (TIMS) and its application to the study of paleo\|environments. Recently, coral samples were determined for their ages on a MAT\|262 mass spectrometer and satisfactory results have been obtained.

Specific Mass Spectrometric Fragmentations from the Dissociation of Intermediate Ion-Neutral Complexes

It is reported that two kinds of specific mass spectrometric fragmentations are generated from dissociations of the intermediates of both the ion-neutral complex and the proton-bound complex. Collision-induced dissociation, isotopic labelling, and semi-empirical AM1 calculations were used to investigate the formation mechanism of the ion of m/z 139 from ionized tetrahydroimidazole-substituted methylene beta-diketones and the unimolecular fragmentations pathway of 3-phenyl-1-butyn-3-ol upon electron impact.

Automatic analytical approach for the determination of 12 illicit drugs and nicotine metabolites in wastewater using on-line SPE-UHPLC-MS/MS

In this study,we developed a novel on-line solid phase extraction(SPE)-ultra-high-performance liquid chromatography tandem mass spectrometry(UHPLC-MS/MS)-based analytical method for simultaneously quantifying 12 illicit drugs and metabolites(methamphetamine,amphetamine,morphine,codeine,6-monoacetylmorphine,benzoylecgonine,3,4-methylenedioxymethamphetamine,3,4-methylenedioxyamphetamine,cocaine,ketamine,norketamine,and methcathinone)and cotinine(COT)in wastewater samples.The analysis was performed by loading 2 m L of the sample onto an Oasis hydrophilic-lipophilic balance cartridge and using a cleanup step(5%methanol)to eliminate interference with a total run time of 13 min.The isotope-labeled internal standard method was used to quantify the target substances and correct for unavoidable losses and matrix effects during the on-line SPE process.Typical analytical characteristics used for method validation were sensitivity,linearity,precision,repeatability,recovery,and matrix effects.The limit of detection(LOD)and limit of quantification(LOQ)of each target were set at 0.20 ng/L and 0.50 ng/L,respectively.The linearity was between 0.5 ng/L and250 ng/L,except for that of COT.The intra-and inter-day precisions were<10.45%and 25.64%,respectively,and the relative recovery ranged from 83.74%to 162.26%.The method was used to analyze various wastewater samples from 33 cities in China,and the results were compared with the experimental results of identical samples analyzed using off-line SPE.The difference rate was between 19.91%and-20.44%,and the error range could be considered acceptable.These findings showed that on-line SPE is a suitable alternative to off-line SPE for the analysis of illicit drugs in samples.

Development of an automatic measurement system using atmospheric pressure photoionization ultrahigh-resolution mass spectrometry and application for on-line analysis of particulate matter

On-line chemical characterization of atmospheric particulate matter(PM)with soft ionization technique and ultrahigh-resolution Mass Spectrometry(UHRMS)provides molecular information of organic constituents in real time.Here we describe the development and application of an automatic measurement system that incorporates PM_(2.5)sampling,thermal desorption,atmospheric pressure photoionization,and UHRMS analysis.Molecular formulas of detected organic compounds were deducted from the accurate(±10 ppm)molecular weights obtained at a mass resolution of 100,000,allowing the identification of small organic compounds in PM_(2.5).Detection efficiencies of 28 standard compounds were determined and we found a high sensitivity and selectivity towards organic amines with limits of detection below 10 pg.As a proof of principle,PM_(2.5)samples collected off-line in winter in the urban area of Beijing were analyzed using the Ionization Module and HRMS of the system.The automatic system was then applied to conduct on-line measurements during the summer time at a time resolution of 2 hr.The detected organic compounds comprised mainly CHON and CHN compounds below 350 m/z.Pronounced seasonal variations in elemental composition were observed with shorter carbon backbones and higher O/C ratios in summer than that in winter.This result is consistent with stronger photochemical reactions and thus a higher oxidation state of organics in summer.Diurnal variation in signal intensity of each formula provides crucial information to reveal its source and formation pathway.In summary,the automatic measurement system serves as an important tool for the on-line characterization and identification of organic species in PM_(2.5).

Detection of Optical Stability of chiral 2-Methylbutyric Acid in Gas Phase with Quadrupole-Quistor-Quadrupole Mass Spectrometer

Optical stability of chiral 2-methylbutyric acid in gas phase has been detected with Quadrupole-Quistor-Quadrupole tandem mass spectrometer in combination with deuteration. The results show that these compounds are optically unstable in the process of self chemical ionization.

Spatial distribution of SiCln （n=O-2） in SICl4 plasma measured by mass spectroscopy

For a better understanding of the deposition mechanism of thin films in SiCl4 source gas, we have measured the spatial distributions of SiCln （n=0-2） radicals in SICl4 radio frequency glow discharge plasma utilizing a mass spectrometer equipped with a movable gas sampling apparatus. The experimental results demonstrate that the relative densities of SiCln （n=0-2） radicals have peak values at the position of 10 mm above the powered electrode along the axial direction; the relative densities of the Si and SiCIn （n=1, 2） radicals have peak values at the positions of 27mm and 7 mm away from the axis along the radial direction, respectively. Generally speaking, in the whole SICl4 plasma bulk region, the relative density of Si is one order of magnitude higher than that of SICl, and the relative density of SiCl is several times higher than that of SICl2. This reveals that Si and SiCl may be the primary growth precursors in forming thin films.

ICP-QQQ-MS法分析婴幼儿谷物辅助食品中镉含量的干扰及其校正

建立三重串联四极杆电感耦合等离子体质谱(inductively coupled plasma triple quadrupole mass spectrometry,ICP-QQQ-MS)法测定婴幼儿谷物辅助食品中镉(Cd)含量的方法。研究单四极杆氦气碰撞模式(SQ-He)、串联四极杆氦气碰撞模式(QQQ-He)、串联四极杆氧气反应模式(QQQ-O_(2))3种碰撞/反应模式下质谱测量中存在的各类干扰,并进行逐一分析、消除。结果显示,抗基体、抗氧化物和多原子离子干扰能力均为QQQ-O_(2)>QQQ-He>SQ-He,采用QQQ-O_(2)模式联合标准加入法可获得更为准确的干扰消除效果。通过引入干扰校正方程,有效解决由于同量异位素锡(Sn)干扰导致的Cd同位素丰度比与天然丰度比不一致问题。QQQ-O_(2)模式下同位素稀释质谱法与标准加入法测量Cd的结果等效一致,证明婴幼儿谷物辅助食品中Cd测量时受到的基体效应和质谱干扰被有效消除。所建方法为使用ICP-QQQ-MS准确测定复杂基体样品中Cd提供重要参考。

基于LC-MS/MS测定人体类固醇激素的研究进展

类固醇激素是一类具有环戊烷多氢菲结构的化合物,由细胞色素P450酶催化形成,在调节机体代谢、促进性器官发育等方面起着重要作用。临床上将类固醇激素水平作为肾上腺疾病、精神类疾病等的诊断指标。液相色谱-串联质谱(LC-MS/MS)联用技术因具有高灵敏度、高通量和高专属性的特点,已成为类固醇临床测定的首选方法。本文综述了LC-MS/MS在内源性类固醇激素测定中的应用,特别是在样品前处理、色谱条件和质谱条件优化等方面的研究进展,为临床上类固醇激素的诊断检测提供参考。

氧气反应模式-四极杆ICP-MS定量高温合金中痕量元素及质谱干扰消除机理研究

本研究建立了氧气反应模式-四极杆电感耦合等离子体质谱(Q-ICP-MS)法准确定量高温合金中痕量杂质元素,对不同碰撞/反应模式消除质谱干扰的效果进行研究。结果表明,氧气动态反应池(DRC-O_(2))模式下,目标元素Cd的多原子离子质谱干扰能够被有效去除;在优化气流为2 mL/min时,信噪比达到最高,检出限较标准模式(STD)降低了近3个数量级。此外,还研究了质谱干扰的消除机理,发现对于元素X(X=Rb、Nb、Mo、Cs、Ta、W或U),当X-O键能大于O-O键能时,质谱干扰组分XO转化成非干扰组分XOO为自发反应,因此,O_(2)充足时更容易生成XOO,从而消除XO干扰。在此基础上,采用高浓度基体模拟溶液(Mo、Nb、Ta、W)分别对痕量Cd、Ag、Au、Hg元素测量的方法学参数进行评估,方法检出限0.08~0.31μg/g、测量重复性相对标准偏差(RSD)2.3%~3.1%(n=6),加标回收率98%~103%,并进一步使用高温合金标准物质验证了方法的可靠性。最后,对3类典型牌号高温合金样品中的痕量杂质进行测量,证明该方法的分析速度快、检出限低、准确可靠,能够满足高温合金中主量Mo、Nb、Ta、W元素存在时被干扰杂质的测量要求。

基于空间代谢组学方法研究人参治疗阿尔兹海默症大鼠的药效物质及作用机制

本文采用基于空气动力辅助解吸电喷雾离子化质谱成像(AFADESI-MSI)技术的空间代谢组学方法,全面探讨了人参在分子水平上治疗阿尔兹海默症(AD)的药效物质基础及作用机制。药效学结果表明,人参提取物可显著改善AD模型大鼠的脑病理损伤状态,提高空间学习记忆能力;代谢组学结果表明,人参显著回调了与AD密切相关的19种生物标志物水平,涉及精氨酸和脯氨酸代谢、嘌呤代谢、三羧酸(TCA)循环和脂肪酸代谢等8条代谢通路。最后,在脑组织中检测出7种人参活性成分,这些物质可能通过调节与神经炎症、神经元损伤、能量缺失以及脂肪酸异常代谢密切相关的代谢途径上游靶点发挥作用,实现对关键代谢物水平的精确调控,从而达到治疗AD的目的。利用质谱成像可以将内外源性物质的空间分布进行对应分析,更清晰地阐释药物成分的具体作用机制。

基于在线质谱定量分析的生物质焦炭还原NO反应动力学

针对生物质焦炭还原NO反应提出基于等效特征图谱法的在线质谱定量分析方法,对固定床等温条件下生物质焦炭还原NO过程进行分析,确定了还原反应过程中每种气体产物的实时质量流量。结果表明:气体产物中CO、CO_(2)和N_(2)同时存在时,使用定量分析方法可将以上3种气体重叠的电流值进行拆分,进而得到每种气体产物的质量流量值。通过与标气对比,验证了定量方法的准确性。针对生物质焦炭还原NO反应,利用基于等效特征图谱法的在线质谱定量分析方法探究了温度对生物质焦炭还原NO反应的影响,并利用模型拟合法对还原反应动力学参数进行求解。结果表明,CO和N_(2)为还原反应的主要产物,参与还原反应的NO中98%的N转化为N_(2)。通过在线质谱定量分析方法计算反应动力学参数表明:800~950℃时机理函数G(x)=1-(1-x)^(1/2)可描述生物质焦炭还原NO反应中焦炭的转化过程,还原反应的活化能为113.46 kJ/mol。

质谱中气相Smiles重排反应的研究进展

人名反应基于反应机理对复杂的有机化学反应进行了梳理和总结,极大地促进了有机化学研究,并方便了化学家们的交流。在质谱领域,气相人名反应的类型并不多,常见的包括麦氏重排(McL)和逆狄尔斯-阿尔德(RDA)反应等。这些广为人知的气相人名反应由于具有显著的结构特异性,成为了质谱结构解析的有力工具。随着软离子化结合多级质谱技术的发展,越来越多新型的气相反应被发现和研究,其中气相Smiles重排反应因其复杂而有趣的骨架重排而备受质谱学家和化学家关注。气相Smiles重排能够引起化合物骨架的变化,导致一些意想不到的中性丢失。与凝聚相Smiles重排反应相比,气相Smiles重排反应不受五元环过渡态形式的限制,也无需碱性条件的引发。这正是气相离子反应的特点,但同时,更多可能的裂解途径也给解谱带来了挑战。系统总结了近年来报道的质谱中气相Smiles重排反应,分析了化合物结构、离子化方法以及电荷状态对气相Smiles重排反应的影响,为基于质谱中气相Smiles重排反应进行化合物结构解析,以及发现化合物在凝聚相条件下的类似反应提供了线索和信息。

The“depict”strategy for discovering new compounds in complex matrices:Lycibarbarspermidines as a case

The comprehensive detection and identification of active ingredients in complex matrices is a crucial challenge.Liquid chromatography coupled with high-resolution mass spectrometry(LC-HRMS)is the most prominent analytical platform for the exploration of novel active compounds from complex matrices.However,the LC-HRMS-based analysis workflow suffers from several bottleneck issues,such as trace content of target compounds,limited acquisition for fragment information,and uncertainty in interpreting relevant MS2 spectra.Lycibarbarspermidines are vital antioxidant active ingredients in Lycii Fructus,while the reported structures are merely focused on dicaffeoylspermidines due to their low content.To comprehensively detect the new structures of lycibarbarspermidine derivatives,a“depict”strategy was developed in this study.First,potential new lycibarbarspermidine derivatives were designed according to the biosynthetic pathway,and a comprehensive database was established,which enlarged the coverage of lycibarbarspermidine derivatives.Second,the polarity-oriented sample preparation of potential new compounds increased the concentration of the target compounds.Third,the construction of the molecular network based on the fragmentation pathway of lycibarbarspermidine derivatives broadened the comprehensiveness of identification.Finally,the weak response signals were captured by data-dependent scanning(DDA)followed by parallel reaction monitoring(PRM),and the efficiency of acquiring MS2 fragment ions of target compounds was significantly improved.Based on the integrated strategy above,210 lycibarbarspermidine derivatives were detected and identified from Lycii Fructus,and in particular,170 potential new compounds were structurally characterized.The integrated strategy improved the sensitivity of detection and the coverage of low-response components,and it is expected to be a promising pipeline for discovering new compounds.

高效液相色谱法同时测定淋洗类化妆品中7种异噻唑啉酮类防腐剂及质谱确证

建立了同时检测淋洗类化妆品中7种异噻唑啉酮类防腐剂的高效液相色谱分析方法及液相色谱-串联质谱确证方法。膏霜乳和液体两种不同基质类型的化妆品样品分别经甲醇超声提取,提取液以离心处理后,取上清液经微孔滤膜过滤后测定。经CAPCELL PAK C_(18)MGIII(4.6 mm×250 mm,5μm)色谱柱分离,以甲醇和0.1%磷酸水溶液为流动相梯度洗脱,流速1.0 ml/min,柱温40℃。检测波长为275,282,和319 nm。以高效液相色谱法的结果进行定性筛查,并采用标准曲线法定量,以液相色谱-串联质谱法的结果进行确证。结果表明,7种异噻唑啉酮类防腐剂在0.1~50 mg/L质量浓度范围内线性关系良好,相关系数均≥0.9999。在低、中、高3种加标浓度水平下,平均加标回收率分别为97.5%~109.9%(膏霜乳)和95.6%~103.6%(液体);相对标准偏差(RSD)小于3.0%,检出限为0.05~0.11 mg/kg。该方法具有简单、快速、准确性好的特点,适用于淋洗类化妆品中7种异噻唑啉酮类防腐剂的含量测定及质谱确证。

液相色谱-串联质谱法测定牛肉中加替沙星残留量的研究

建立牛肉中加替沙星残留量检测的液相色谱-串联质谱(liquid chromatography-tandem mass spectrometry,LC-MS/MS)方法。牛肉样品经80%(V/V)乙腈溶液提取,Prime HLB固相萃取柱净化。采用0.1%甲酸(V/V)-甲醇溶液和0.1%甲酸(V/V)-水溶液进行梯度洗脱,电喷雾离子源正离子扫描模式(ESI^(+)),多反应监测(MRM),内标法定量。结果表明,加替沙星进样浓度在1~100 ng/mL范围内与峰面积呈良好的线性关系(r^(2)=0.999);方法检出限和定量限分别为1.0和2.0μg/kg;在2.0、4.0、50μg/kg 3个添加水平上,回收率在64.2%~114.6%之间,相对标准偏差为5.5%~9.7%(n=6)。本方法快速、准确、灵敏,适用于牛肉中加替沙星残留量检测。

发热伴血小板减少综合征病毒非结构蛋白的表达和定位及宿主互作蛋白的筛选和分析

目的:通过免疫沉淀联合质谱分析的方法筛选发热伴血小板减少综合征病毒(SFTSV)非结构蛋白(NSs)的宿主互相作用(互作)蛋白,探讨互作蛋白的功能、亚细胞定位及参与的生物途径,为阐明SFTSV的复制和致病机制提供依据。方法:将真核表达载体pSFTSV-NSs-Flag (实验组)和Flag-CMV-3 (阴性组)分别转染进人胚胎肾293T细胞中,同时设置空白组(不进行任何处理)。收集各组细胞裂解液,采用间接免疫荧光和Western blotting法验证SFTSV NSs在宿主细胞中的表达及定位。蛋白裂解液经protein A/G处理,采用免疫沉淀法富集与NSs结合的宿主蛋白,通过银染和考马斯亮蓝染色初步分析捕获的互作蛋白,观察各组蛋白差异条带。采用液相色谱和串联质谱技术得到蛋白质的序列信息,保留可信蛋白基于UniProt数据库检索,对鉴定到的蛋白进行基因本体论(GO)功能富集分析、蛋白结构域和功能位点数据库(IPR)、真核生物同源蛋白簇(KOGs)功能注释、京都基因与基因组百科全书(KEGG)信号通路富集分析、亚细胞定位和转录因子(TF)功能注释,确定互作蛋白的亚细胞结构、基因功能及参与的生物过程。结果:SFTSV NSs在相对分子质量33 000处表达单一特异性条带,免疫荧光检测其定位于细胞质中,且聚集呈砂粒体包涵体样。银染和考马斯亮蓝染色,实验组和阴性组均存在显著差异条带。质谱筛选出46种潜在互作蛋白;GO功能富集分析、KOGs功能注释和KEGG信号通路富集分析,与病毒翻译、细胞代谢及蛋白质运输相关的生物途径富集到较多数目的蛋白,注释中有8种蛋白具有中间丝蛋白结构域。亚细胞定位所占百分率最高的是细胞质蛋白;与NSs定位场所一致。TF功能注释,有1种蛋白来自NF-Y家族。结论:互作蛋白在协助蛋白质正确折叠、参与核糖体翻译和构成细胞骨架等进程中发挥作用,可能参与了抗病毒复制,可作为候选蛋白进一步研究SFTSV的复制机制。