用于水中有机磷农药检测的离子迁移率谱仪预富集进样方法

建立了检测水中有机磷农药的离子迁移率谱仪预富集进样方法。预富集器由表面覆盖有吸附薄膜的微热板、聚四氟乙烯电路板和管座组成,具有操作简单,无需有机溶剂,自加热,热容小,功耗低等优点。以马拉硫磷检测为例,分析了富集器解吸升温速率和离子迁移率谱仪半透膜温度对检测结果的影响。采用高温短时脉冲加热和低温维持加热相结合的解吸方式,既可形成较高的进样浓度脉冲,又可减少进入漂移管的杂质,有利于提高离子迁移率谱仪检测灵敏度。实验表明:采用所述预富集及两阶段加热解吸进样方法,对水中马拉硫磷的检出限为3.9μg/L,达到了国家标准对水中有机磷检测的要求。     

基于微热板表面离子化源的离子迁移率谱仪研究

根据表面离化机理和离子迁移率谱检测方式,设计和制备了一种基于表面离化源的离子迁移率谱仪(IMS)。表面离化源为采用微机电系统(MEMS)工艺加工的微热板阵列,除了作为离子产生器,还作为漂移管的一个离子栅,用以实现离子向漂移区的注入。测试了该IMS对三乙胺的响应特性并研究了离子注入时间对离子迁移率谱的影响。结果表明,基于微热板表面离化源的离子迁移率谱仪对三乙胺具有很好的动态响应特性,三乙胺浓度的平方根与离子峰面积具有较好的线性关系,检出限可达6×10-8(V/V)。此外,与传统的放射离化IMS相比,这种IMS还具有离子注入时间短和离子迁移率谱基电流为零等特点。     

基于离子迁移谱及一氧化氮掺杂检测甲硫醇

针对低浓度甲硫醇快速检测需求,开展了以一氧化氮作为掺杂剂的离子迁移谱检测方法研究。设计并搭建了电晕放电离子迁移谱检测系统,优化了系统工作参数：漂移管工作温度180℃,放电电压10.5 kV,掺杂流量160 mL/min,进样流量150 mL/min。在优化参数下检测不同浓度的甲硫醇气体标准样品,结果表明掺杂一氧化氮明显提高了检测甲硫醇的灵敏度,理论检出限可达4.2×10-4 mg/m3,满足国家标准一级厂界要求。     

微波诱导等离子体离子迁移谱仪性能及影响因素的研究

离子迁移谱仪的性能受到多种因素的影响,如漂移管电场强度离子门脉冲宽度、离子源工作条件、漂移管尺寸、离子门加工工艺和屏蔽网透过率等。在实际应用中需要对漂移管电场强度和离子门脉冲宽度进行调整以平衡灵敏度和分辨率。本研究详细研究了漂移管电场强度和离子门脉冲宽度对微波诱导等离子体离子迁移谱( MIPI-IMS)分辨率和灵敏度的影响。实验结果表明,存在一个最佳电场强度值使得分辨率达到最大,而且不同离子门脉冲宽度对应的最佳电场强度值不同;增大电场强度和离子门脉冲宽度有利于灵敏度的提升。与其它离子流较弱的离子源相比,离子流较大的微波诱导等离子体离子源在实际应用中对离子门脉冲宽度和漂移管电场强度有更多的选择。此研究结果有助于MIPI-IMS仪器性能的提升。将异丙醇用于测试MIPI-IMS的性能,结果表明,MIPI-IMS在保持较低检出限(7.7×10-11, V/V)的同时,分辨率可以达到66。     

电喷雾离子迁移谱检测氨基酸及多肽的研究

建立了氨基酸及多肽的电喷雾离子迁移谱检测方法.采用自制的电喷雾离子迁移谱装置,在室温条件下以甲醇为溶剂,空气为漂移气体,流速为1000 mL/min,电喷液流速为2 mL/min,测试了甘氨酸、胱氨酸、组氨酸、精氨酸4种氨基酸及缓激肽片段(1~7)和P物质2种多肽的离子迁移谱,计算出上述化合物的约化迁移率.离子迁移谱图反映出化合物的结构信息,具有指纹谱特征.此装置在1 min的检测时间内对P物质的检测灵敏度达到855 ng/mL.结果表明,电喷雾离子迁移谱可用于氨基酸及多肽类化合物的现场快速鉴定.     

多束毛细管柱–离子迁移率谱检测环境大气中的苯系物

采用多束毛细管柱–离子迁移率谱(MCC–IMS)系统对环境大气中的苯、甲苯、乙苯、二甲苯和苯乙烯5种苯系物进行快速检测。IMS漂移管温度为80℃,载气和漂移气均为洁净空气,测得苯系物的约化迁移率。苯、甲苯、乙苯、二甲苯和苯乙烯分别在0.20~3.00,0.20~2.00,0.15~1.00,0.25~3.00,0.08~1.00 mg/m~3质量浓度范围内线性良好,线性相关系数均不小于0.96。基于3倍噪声计算,苯、甲苯、乙苯、二甲苯和苯乙烯的检出限分别为0.055,0.023,0.017,0.065和0.013 mg/m~3。MCC–IMS法可快速检测混合样品中5种苯系物,其中苯、甲苯和苯乙烯的定量相对误差分别为5.0%,9.4%,0.2%,测定结果的相对标准偏差分别为2.7%,5.0%,6.7%(n=6)。MCC–IMS的单次测量可在3 min内完成。     

离子迁移管中湿度变化对毒品和烟酰胺检测的影响

通过改变离子管内部的载气湿度,来监测冰毒、氯胺酮和可卡因等3种毒品以及烟酰胺的探测灵敏度和迁移率。实验结果显示,离子管内气体湿度从1%到30%变化时,烟酰胺、冰毒、氯胺酮和可卡因4种样品的特征峰强度分别下降了61%,37%,39%和64%;而它们的迁移时间分别增加了0.75,0.55,0.325和0.225 ms。4种样品的灵敏度随着湿度的增加有不同程度的下降,样品的迁移时间随湿度的变化存在一定规律性,即迁移时间小(迁移率大)的样品其受湿度影响更为显著。上述规律性的存在也使得现有数据库对样品迁移时间偏移值的定义需要做出修正。     

离子迁移谱快速筛查白酒中痕量邻苯二甲酸酯的研究

建立了离子迁移谱技术快速检测白酒中痕量邻苯二甲酸酯的方法。对迁移管温度、进样口温度进行了参数优化后,选取5种典型的邻苯二甲酸酯进行了系统研究。在迁移管和进样口温度分别为90℃和160℃的条件下,邻苯二甲酸二甲酯、邻苯二甲酸二乙酯、邻苯二甲酸二丁酯、邻苯二甲酸二异丁酯和邻苯二甲酸二(2-乙基己)酯的检出限分别为0.14,0.06,0.14,0.44和0.02 mg/L;9次平行测量的相对标准偏差RSD<8.9%,单个样品的分析周期小于95 s。将本方法应用于5种白酒盲样的检测,成功筛查出邻苯二甲酸酯类物质。利用离子阱质谱对5种邻苯二甲酸酯标样产物离子和白酒盲样的产物离子进行了确认,结果表明,离子迁移谱的谱峰是邻苯二甲酸酯离子。这说明丙酮作为掺杂剂,可以避免白酒中背景化合物的干扰。本方法适于大量白酒样品中邻苯二甲酸酯类物质的快速筛查。     

迁移管的电场强度对真空紫外电离-离子迁移谱仪性能的影响

离子迁移管是离子迁移谱仪的核心部分,它用来产生均匀的电场,以使不同迁移率的离子进行分离。本研究以丙酮为例,详细研究了本课题组所研制的真空紫外电离源-离子迁移谱仪中迁移管的电场参数对离子的灵敏度和分辨率的影响,发现电压的增大灵敏度增大,但是分辨率存在一个最佳的电压,这些结果可用于迁移谱的优化设计。     

液相色谱-电喷雾电离-离子迁移谱联用法测定中药口服液中7种指标性成分

采用液相色谱-电喷雾电离-离子迁移谱联用技术，研究建立了中药口服液中丹参素、甘草酸、天麻素、绿原酸、葛根素、黄芩苷、芦丁等7种指标性成分的二维分离分析方法。样品溶液首先经ACQUITY UPLC BEH C₁₈色谱柱（50 mm×1 mm，1.7 μm）分离后，导入可调节式分流器（分流比50 ∶ 1），柱后流出液分别进入离子迁移谱和三重四极杆质谱检测。分别详细优化了液相色谱、喷雾电压、迁移管和气体预加热温度、漂移气流速等实验条件，同时建立了指标性成分的液相色谱-三重四极杆质谱确证方法。7种中药指标性成分的检出限为2~10 μg/mL，定量限为5~25 μg/mL。采用本方法对中药口服液实际样品进行了检测分析。通过将液相色谱和离子迁移谱进行偶联，可实现目标化合物同时基于疏水性和离子迁移率差异的二维分离，获得更为丰富的测试信息。     

Electron capture ion mobility spectrometry for the selective detection of chlorinated and brominated species after capillary gas chromatography

This paper reports the first investigation of electron capture ion mobility spectrometry as a detection method for capillary gas chromatography. In previous work with negative ion mobility detection after gas chromatography, the principal reactant ion species were O₂^? or hydrated O₂^? due to the presence of oxygen in the drift gas. These molecular reactant ions have a mobility similar to chloride and bromide ions, which are the principal product ions formed by most halogenated organics via dissociative ion-molecule reactions. Oxygenated reactant ions thus interfere with the selective detection of chloride and bromide product ions. A recently described ion mobility detector design efficiently eliminated ambient impurities, including oxygen, from infiltrating the ionization region of the detector; consequently, in the negative mode of operation, the ionization species with N₂ drift gas were thermalized electrons. Thermalized electrons have a high mobility and their drift time occupies a region of the ion mobility spectrum not occupied by chloride, bromide, or other product ions. The result was improved selectivity for halogenated organics which ionize by dissociative electron capture. This was demonstrated by the selective detection of 4,4′-dibromobiphenyl from the components of a polychlorinated biphenyl mixture (Aroclor 1248).     

Ion Mobility Sensor In Environmental Analytical Chemistry—Concept And First Results

Abstract

Ion mobility spectrometry is a technique for generating ions at atmospheric pressure via ion-molecule reactions, and for analysing them in an ion drift tube.

The time required for the ions to traverse the length of the drift tube is mainly a function of the mass and the charge of the ions. Besides, ion shape and polarizability also affect the drift time.

Ion mobility spectrometry does not allow structural identification and quantification of unknown substances in mixtures. However, under certain boundary conditions it provides selective fingerprints of the substances to be observed, and operates at the ppbv concentration level and the millisecond time scale.

Through further miniaturization of a recently developed instrument of this type an ion mobility sensor is to be constructed. This sensor includes drift channel, operating shutter, collecting electrode, electronic data acquisition and translation board. The sensor makes possible to obtain real-time ion mobility spectra.

We present and discuss the concept of a small ion mobility spectrometer, its operation principle and first results on the way towards its further miniaturization.     

Corona Discharge Ion Mobility Spectrometry of Ten Alcohols

Ion mobility spectra for ten alcohols have been studied in an ion mobility spectrometry apparatus equipped with a corona discharge ionization source. Using protonated water cluster ions as the reactant ions and clean air as the drift gas, the alcohols exhibit different product ion characteristic peaks in their ion mobility spectra. The detection limit for these alcohols is at low concentration pmol/L level according to the concentration calibration by exponential dilution method. Based on the measured ion mobilities, several chemical physics parameters of the ion-molecular interaction at atmosphere were obtained, including the ionic collision cross sections, diffusion coefficients, collision rate constants, and the ionic radii under the hard-sphere model approximation.     

离子迁移谱定量检测复杂基质中新型炸药六亚甲基三过氧化二胺

六亚甲基三过氧化二胺( Hexamethylene triperoxide diamine, HMTD)是一种新型有机过氧化爆炸物,由于原料易得、制备方法简单,常被用于恐怖袭击和犯罪活动中。本实验基于非放射性电离源真空紫外灯( VUV)发展了一种试剂分子辅助灯电离正离子迁移谱技术,通过优化筛选试剂分子,最终选择丙酮作为HMTD定量检测的试剂分子。利用质谱对丙酮的反应试剂离子和HMTD的产物离子进行了离子归属,确定反应试剂离子为丙酮二聚体离子 m/z 117[( CH3)2 CO ]2 H+, HMTD 的产物离子为其质子化的分子离子m/z 209[ HMTD+H]+。在迁移管和热解析温度120℃的条件下,利用HMTD最大信号强度和第10 s的信号强度对其标准样品进行定量检测,线性范围分别为5~50 ng/μL和5~100 ng/μL,检出限分别可达0.2和0.3 ng/μL。化妆品如香水等常常干扰和抑制离子迁移谱测量,发展在香水基质中HMTD的现场快速筛查和检测方法具有现实意义。将这两种定量方法应用于3种不同品牌香水样品中HMTD的定量检测,对比发现利用HMTD第10 s的信号强度进行定量具有较好的回收率和准确性,该方法适用于复杂基质中HMTD的准确快速定量检测。     

一种微型FAIMS传感器芯片的研制

基于微机电系统(MEMS)技术,研制了一种微型高场非对称波形离子迁移谱(FAIMS)传感器芯片.芯片尺寸为18.8mm×12.4mm×1.2mm,由离子化区、迁移区、离子检测区组成.采用真空紫外灯离子源在大气压环境下对样品进行离子化,经过离子化区中聚焦电极的电场作用,实现离子在进入迁移区之前的聚焦,提高离子信号的强度.通过在上下玻璃上溅射Au/Cr(300nm/30nm)金属,并与厚度为200μm、采用感应耦合等离子体(ICP)工艺刻蚀的硅片键合,形成迁移区的矩形通道,尺寸为10mm×5mm×0.2mm.离子检测区为三排直径200μm、间距100μm交错排列的圆柱阵列式微法拉第筒,能同时检测正负离子.采用频率为2MHz,最大电压为364V,占空比为30%的高场非对称方波电压进行FAIMS芯片实验.以丙酮和甲苯为实验样品,载气流速80L·h-1,补偿电压从-10V到3V以0.1V的步长进行扫描,得到了丙酮和甲苯的FAIMS谱图,验证了FAIMS芯片的性能.丙酮和甲苯的FAIMS-MS实验进一步表明FAIMS系统实现了离子分离和过滤功能.     

Ion mobility spectrometric analysis of vaporous chemical warfare agents by the instrument with corona discharge ionization ammonia dopant ambient temperature operation

The ion mobility behavior of nineteen chemical warfare agents (7 nerve gases, 5 blister agents, 2 lachrymators, 2 blood agents, 3 choking agents) and related compounds including simulants (8 agents) and organic solvents (39) was comparably investigated by the ion mobility spectrometry instrument utilizing weak electric field linear drift tube with corona discharge ionization, ammonia doping, purified inner air drift flow circulation operated at ambient temperature and pressure. Three alkyl methylphosphonofluoridates, tabun, and four organophosphorus simulants gave the intense characteristic positive monomer-derived ion peaks and small dimer-derived ion peaks, and the later ion peaks were increased with the vapor concentrations. VX, RVX and tabun gave both characteristic positive monomer-derived ions and degradation product ions. Nitrogen mustards gave the intense characteristic positive ion peaks, and in addition distinctive negative ion peak appeared from HN3. Mustard gas, lewisite 1, o-chlorobenzylidenemalononitrile and 2-mercaptoethanol gave the characteristic negative ion peaks. Methylphosphonyl difluoride, 2-chloroacetophenone and 1,4-thioxane gave the characteristic ion peaks both in the positive and negative ion mode. 2-Chloroethylethylsulfide and allylisothiocyanate gave weak ion peaks. The marker ion peaks derived from two blood agents and three choking agents were very close to the reactant ion peak in negative ion mode and the respective reduced ion mobility was fluctuated. The reduced ion mobility of the CWA monomer-derived peaks were positively correlated with molecular masses among structurally similar agents such as G-type nerve gases and organophosphorus simulants; V-type nerve gases and nitrogen mustards. The slope values of the calibration plots of the peak heights of the characteristic marker ions versus the vapor concentrations are related to the detection sensitivity, and within chemical warfare agents examined the slope values for sarin, soman, tabun and nitrogen mustards were higher. Some CWA simulants and organic solvents gave the ion peaks eluting at the similar positions of the CWAs, resulting in false positive alarms.     

Peak Profile Analysis in High Field Asymmetric Wave Ion Mobility Spectrometry

High field asymmetric wave ion mobility spectrometry (FAIMS) is a powerful tool to detect and characterize gas-phase ions, while the unsolvable partial differential equation of ions moving in ion drift tube poses a big challenge to FAIMS spectral peak analysis. In this work, a universal and effective model of FAIMS spectral peak profile has been proposed by introducing ion trajectory and loss height. With this model, the influence of the structure of ion drift tube, dispersion voltages, compensation voltages, and carrier gas flow rate on the FAIMS spectral peak characteristics like peak shape, full width at half maximum and peak height is analyzed and discussed. The results show that the influence of different factors on the FAIMS spectral peak profile can be qualitatively described by the model which agrees with the experimental data.     

Buffer gas additives (modifiers/shift reagents) in ion mobility spectrometry: Applications,predictions of mobility shifts,and influence of interaction energy and structure

Ion mobility spectrometry (IMS) is an analytical technique used for fast and sensitive detection of illegal substances in customs and airports, diagnosis of diseases through detection of metabolites in breath, fundamental studies in physics and chemistry, space exploration, and many more applications. Ion mobility spectrometry separates ions in the gas‐phase drifting under an electric field according to their size to charge ratio. Ion mobility spectrometry disadvantages are false positives that delay transportation, compromise patient's health and other negative issues when IMS is used for detection. To prevent false positives, IMS measures the ion mobilities in 2 different conditions, in pure buffer gas or when shift reagents (SRs) are introduced in this gas, providing 2 different characteristic properties of the ion and increasing the chances of right identification. Mobility shifts with the introduction of SRs in the buffer gas are due to clustering of analyte ions with SRs. Effective SRs are polar volatile compounds with free electron pairs with a tendency to form clusters with the analyte ion. Formation of clusters is favored by formation of stable analyte ion‐SR hydrogen bonds, high analytes' proton affinity, and low steric hindrance in the ion charge while stabilization of ion charge by resonance may disfavor it. Inductive effects and the number of adduction sites also affect cluster formation. The prediction of IMS separations of overlapping peaks is important because it simplifies a trial and error procedure. Doping experiments to simplify IMS spectra by changing the ion‐analyte reactions forming the so‐called alternative reactant ions are not considered in this review and techniques other than drift tube IMS are marginally covered.