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.     

载气流速对高场不对称波形离子迁移谱的影响

载气流速是影响高场不对称波形离子迁移谱(FAIMS)的重要参数.以自制的高场不对称波形离子迁移谱仪为实验平台,在射频电场幅值3 kV/cm,频率500 kHz,占空比0.36的条件下,研究了载气流速对苯离子迁移谱谱峰强度和半峰宽的影响.实验结果表明: 载气流速为3.7 L/min时,苯样品的谱峰强度最大,仪器的灵敏度最高.随着载气流速的增加,谱峰半峰宽变宽,仪器的分辨率下降.载气流速为3 .0～3.7 L/min时仪器综合性能最佳.此结果对于控制迁移谱仪载气流速有重要的参考意义.     

电感耦合等离子体质谱法测定氧化钕中砷含量

建立草酸沉淀分离氧化钕,用校正方程消除残余钕离子产生的双电荷离子干扰,电感耦合等离子体质谱法测定砷含量的方法。选择了溶解样品条件,硝酸溶解样品即能满足检测要求;优化了仪器条件,功率1500W,雾化器流量0.86L/min;进行了内标元素的选择,确定Rh为最佳校正内标元素;确定用草酸分离基体并结合干扰校正方程消除钕的双电荷离子干扰;方法检出限为0.029 ng/mL,定量限为0.097 ng/mL。采用方法对实际样品进行测定,回收率(n=11)为94%～104%,相对标准偏差(RSD,n=11)为0.56%～5.82%。     

电感耦合等离子体质谱(ICP-MS)法测定氧化钕中砷含量

建立了草酸沉淀分离氧化钕,用校正方程消除残余钕离子产生的双电荷离子干扰,电感耦合等离子体质谱(ICP-MS)法测定砷含量的方法。选择了溶解样品条件,硝酸溶解样品即能满足检测要求;优化了仪器条件,射频功率1 500 W,雾化器流量0.86L/min;进行了内标元素的选择,确定Rh为最佳校正内标元素;确定用草酸分离基体并结合干扰校正方程消除钕的双电荷离子干扰;方法检出限为0.029ng/mL,定量限为0.097ng/mL。对实际样品进行测定,加标回收率为94%~104%,相对标准偏差(RSD,n=11)为0.56%~5.8%。方法操作简单,快速、准确,加标回收率及相对标准偏差满足日常检测要求。     

木制儿童用品中6种木材防腐剂的迁移规律研究

基于气相色谱-串联质谱(GC-MS/MS)技术建立了6种防腐剂总量及迁移量的测定方法,通过搭建迁移装置并模拟实际暴露场景,对自制阳性样品中6种防腐剂在模拟唾液和汗液中的迁移规律进行研究,并计算出不同时刻的迁移率。结果表明,在迁移2 min~96 h范围内,防腐剂的迁移量均随时间延长而逐渐增大,最终达到迁移平衡,迁移率为2.1%~61.7%(唾液),2.2%~86.4%(汗液)。在样品与模拟液仅接触2 min时有6种物质检出,迁移率分别为2.1%~4.2%(唾液)和2.2%~3.3%(汗液)。部分实际样品中检出了2,4-二氯苯酚和2,4,6-三氯苯酚,鉴于儿童日常生活中短时间持续接触样品的特点,选取两个实际阳性样品测定了其在2~30 min的迁移量及迁移率。     

离子液体内耦合液膜迁移苯酚的研究

本文以N-甲基咪唑为原料,采用微波合成法,制备了疏水性离子液体1-丁基-3-甲基咪唑六氟磷酸盐([BMIM]PF6),并将其作为液膜,对苯酚的内耦合液膜迁移进行了研究,考察了温度、搅拌速度、料液相酸度、初始浓度及解析相NaOH浓度等因素对苯酚迁移的影响,得出了最佳迁移条件:温度300 K,搅拌速度350 r/min,料液相pH为3.65,解析相NaOH浓度为0.8 mol/L.在最佳液膜条件下,对于10 mg/L苯酚溶液,迁移110 min,迁移率可以达到97.3%,膜相中有少量苯酚滞留.离子液体可循环使用.     

纸质包装材料中甲醛、乙醛向食品模拟物改性聚苯醚的迁移行为

为了解纸质包装材料中甲醛、乙醛向食品模拟物改性聚苯醚( Tenax)中的迁移行为,建立了一步提取衍生化、超高效液相色谱测定纸质包装材料和Tenax中的甲醛和乙醛的方法。本方法在甲醛和乙醛的测定范围内,线性相关系数R2>0.9999,甲醛检出限为0.03 mg/m2,乙醛检出限为0.04 mg/m2,测定纸样和Tenax的加标回收率为90.1%~108.6%。采用本方法研究不同温度和时间下两种纸质包装材料中甲醛、乙醛向Tenax中的迁移规律。研究表明,甲醛、乙醛迁移行为随时间变化趋势大致相同,均呈现迁移率随迁移时间延长先迅速增大,后又减小达到一个常数;甲醛和乙醛迁移率受温度的影响不同,达到平衡后,甲醛在30℃下迁移率最高,乙醛在70℃和50℃下迁移率高;甲醛和乙醛向Tenax中的迁移率差异较大,达到平衡后,乙醛的迁移率远高于甲醛。     

三正辛胺-二甲苯液膜迁移Cd(Ⅱ)的研究

研究了三正辛胺-二甲苯支撑液膜体系中搅拌速率、反萃剂、三正辛胺浓度、料液中H+浓度等因素对Cd(Ⅱ)离子迁移的影响.用大块液膜测定了不同温度时Cd(Ⅱ)离子跨膜迁移的萃取及反萃取的表观速率常数k₁和k_2.实验表明,温度升高,k₁和k₂均增大(k₁>k₂),且达到膜相最大镉离子浓度时所需的时间逐渐减少.膜相积累的镉离子浓度达最大时,Cd(Ⅱ)离子跨膜传输为稳态传输.根据Arrhenious关系得到膜相萃取反应和反萃取反应的活化能分别为23.8和19.3kJ/mol.     

离子液体作高效液相色谱流动相添加剂分离测定芳香胺

建立了以离子液体作反相高效液相色谱流动相添加剂分离测定邻苯二胺、苯胺和对甲苯胺3种芳香胺的方法。实验以C18反相色谱柱为分离柱,采用紫外检测方法,考察了检测波长、甲醇含量、咪唑离子液体烷基链长度、离子液体溶液浓度等条件对分离和测定的影响,并与其它分离测定芳香胺的方法进行了比较。优化的色谱条件为:以甲醇/1-丁基-3-甲基咪唑四氟硼酸盐水溶液(3.0mmol/L,乙酸调节pH 3.5)=30/70(V/V)为流动相;检测波长254 nm;流速1.0mL/min;柱温30℃。在此条件下,3种芳香胺达到基线分离,在6.5 min之内分离完全;在1～40 mg/L范围内,线性回归方程的相关系数达到0.99以上;检出限为0.07～0.41 mg/L。将本方法应用于废水的测定,加标回收率在92.3%～96.7%之间,相对标准偏差小于3.5%。     

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。     

Development of an ion mobility spectrometer for use in an atmospheric pressure ionization ion mobility spectrometer/mass spectrometer instrument for fast screening analysis

An ion mobility spectrometer that can easily be installed as an intermediate component between a commercial triple-quadrupole mass spectrometer and its original atmospheric pressure ionization (API) sources was developed. The curtain gas from the mass spectrometer is also used as the ion mobility spectrometer drift gas. The design of the ion mobility spectrometer allows reasonably fast installation (about 1 h), and thus the ion mobility spectrometer can be considered as an accessory of the mass spectrometer. The ion mobility spectrometer module can also be used as an independently operated device when equipped with a Faraday cup detector. The drift tube of the ion mobility spectrometer module consists of inlet, desolvation, drift, and extraction regions. The desolvation, drift and extraction regions are separated by ion gates. The inlet region has the shape of a stainless steel cup equipped with a small orifice. Ion mobility spectrometer drift gas is introduced through a curtain gas line from an original flange of the mass spectrometer. After passing through the drift tube, the drift gas serves as a curtain gas for the ion-sampling orifice of the ion mobility spectrometer before entering the ion source. Counterflow of the drift gas improves evaporation of the solvent from the electrosprayed sample. Drift gas is pumped away from the ion source through the original exhaust orifice of the ion source. Initial characterization of the ion mobility spectrometer device includes determination of resolving power values for a selected set of test compounds, separation of a simple mixture, and comparison of the sensitivity of the electrospray ionization ion mobility spectrometry/mass spectrometry (ESI-IMS/MS) mode with that of the ESI-MS mode. A resolving power of 80 was measured for 2,6-di-tert-butylpyridine in a 333 V/cm drift field at room temperature and with a 0.2 ms ion gate opening time. The resolving power was shown to be dependent on drift gas flow rate for all studied ion gate opening times. Resolving power improved as the drift gas flow increased, e.g. at a 0.5 ms gate opening time, a resolving power of 31 was obtained with a 0.65 L/min flow rate and 47 with a 1.3 L/min flow rate for tetrabutylammonium iodide. The measured limits of detection with ESI-MS and with ESI-IMS/MS modes were similar, demonstrating that signal losses in the IMS device are minimal when it is operated in a continuous flow mode. Based on these preliminary results, the IMS/MS instrument is anticipated to have potential for fast screening analysis that can be applied, for example, in environmental and drug analysis.     

Coupling of capillary electrophoresis with electrospray ionization multiplexing ion mobility spectrometry

In this work, ion mobility spectrometry (IMS) function as a detector and another dimension of separation was coupled with CE to achieve two‐dimensional separation. To improve the performance of hyphenated CE‐IMS instrument, electrospray ionization correlation ion mobility spectrometry is evaluated and compared with traditional signal averaging data acquisition method using tetraalkylammonium bromide compounds. The effect of various parameters on the separation including sample introduction, sheath fluid of CE and drift gas, data acquisition method of IMS were investigated. The experimental result shows that the optimal conditions are as follows: hydrodynamic sample injection method, the electrophoresis voltage is 10 kilo volts, 5 mmol/L ammonium acetate buffer solution containing 80% acetonitrile as both the background electrolyte and the electrospray ionization sheath fluid, the ESI liquid flow rate is 4.5 μL/min, the drift voltage is 10.5 kilo volts, the drift gas temperature is 383 K and the drift gas flow rate is 300 mL/min. Under the above conditions, the mixture standards of seven tetraalkylammoniums can be completely separated within 10 min both by CE and IMS. The linear range was 5–250 μg/mL, with LOD of 0.152, 0.204, 0.277, 0.382, 0.466, 0.623 and 0.892 μg/mL, respectively. Compared with traditional capillary electrophoresis detection methods, the developed CE‐ESI‐IMS method not only provide two sets of qualitative parameters including electrophoresis migration time and ion drift time, ion mobility spectrometer can also provide an additional dimension of separation and could apply to the detection ultra‐violet transparent compounds or none fluorescent compounds.     

Monte Carlo simulation of ion transport in ion mobility spectrometry

A program for simulation of ion trajectories in ion mobility spectrometry (IMS) instruments has been developed and incorporated into SIMION 7.0 [Int. J. Mass Spectrom. 200 (2000) 3–25]. Simulations were based on elastic collisions between ions and gas particles and conducted for an IMS drift tube. The program was validated by comparing the reduced mobility of helium ions derived from the simulation with the experimental data for helium ions in neon drift gas in low electric fields. Typical IMS parameters, including pressure, temperature, and flow rate of the drift gas were taken into account in the simulations. The program demonstrates capabilities of generating IMS spectra and predicting ion transport efficiency and separating ions. For the IMS drift tube studied, a correlation between imperfection of the electric field distribution and low resolution has been observed.     

CHCl3电子吸附速率常数的离子迁移谱

The dissociative electron attachment process for CHCl₃ at different electric field have been studied with nitrogen as drift and carrier gas using corona discharge ionization source ion mobility spectrometry (CD-IMS). The corresponding electron attachment rate constants varied from 1.26×10^-8 cm³/(molecules s) to 8.24×10^-9 cm³/(molecules s) as the electric field changed from 200 V/cm to 500 V/cm. At a fixed electric field in the drift region,the attachment rate constants are also detected at different sample concentration. The ion-molecule reaction rate constants for the further reaction between Cl^- and CHCl₃ are also detected, which indicates that the technique maybe becomes a new method to research the rate constants between ions and neural molecules. And the reaction rate constants between Cl^- and CHCl₃ are the first time detected using CD-IMS.     

高效液相色谱与纳流电喷雾阵列Chirp Z变换离子迁移谱联用方法研究

利用柱后分流频率调制Chirp Z变换离子迁移谱(IMS),建立了高效液相色谱与纳流电喷雾阵列Chirp Z变换离子迁移谱(HPLC-NanoESI-Chirp Z IMS)联用分析方法,考察了喷雾电压、溶剂组成、溶液流速等参数对NanoESI-Chirp Z IMS信噪比的影响.在此基础上,利用建立的方法对一系列四烷基溴化铵类化合物进行测定,并比较了Chirp Z变换法和FT变换法两种方法的信噪比和分辨率.实验结果表明,最佳实验条件为: 喷雾电压4.5 kV;溶剂组成90%甲醇;ESI溶液流速为8 μL/min. 利用HPLC-NanoESI-Chirp Z IMS联用方法成功测定了四丁基溴化铵、四戊基溴化铵、四己基溴化铵、四庚基溴化铵、四辛基溴化铵烷、四癸基溴化铵组成的混合样品.与传统信号平均离子迁移谱相比,Chirp Z变换离子迁移谱的信噪比更高,其迁移时间的测定精度优于傅里叶变换离子迁移谱.     

A novel ion detector aiming at the homogeneous of drift gas

In standalone ion mobility spectrometry (IMS) instruments, the effect of drift gas turbulence reduces the sensitivity and resolution of the instrument. A traditional ion detector constructed with a Faraday plate and used to detect ions in an IMS is positioned at the end of the drift region. Drift gas flowing through this detector may introduce turbulence near the detector, possibly affecting the sensitivity and resolution of the device. To address this problem, a novel Faraday detector with a double layer structure was constructed. A number of dense and staggered holes were created on each layer of the detector. This design enabled the drift gas to pass through the holes of the detector, and the staggered nature of holes in the detector ensured that the ions could be detected. Theoretical simulations were conducted using the finite element method to obtain velocity distributions for both a standard Faraday detector and the modified Faraday detector. The results indicated that the novel ion detector created a homogenous gas under at high inlet flow rate while turbulence was still evident for the traditional Faraday detector. When the inlet flow rate was 1000 mL/min, the range of the unstable region of the drift gas in the axis of the drift tube with the novel ion detector was reduced by 97% relative to that for the traditional detector. The data suggests that due to such gains, sensitivity and resolution may be improved for standalone IMS instruments.     

紫外光离子源-高场不对称波形离子迁移谱检测环境中挥发性有机物

本研究采用紫外光离子源-高场不对称波形离子迁移谱(UV-FAIMS)快速检测环境中挥发性有机物.选取苯和对二甲苯为研究对象,并分析了分离电压、流速等因素对其分离识别的影响.实验结果表明:当分离电压值为0～1200 V时,苯和对二甲苯信号强度逐渐降低,而特征补偿电压值却逐渐增加.实验选取分离电压值为900 V,当载气流速为0～240 L/h时,苯和对二甲苯的特征离子峰信号强度逐渐增加,当载气流速为0～120 L/h时,苯和对二甲苯团簇峰信号强度增加,当载气流速为120～240 L/h时,苯的团簇峰信号强度增加,而对二甲苯的团簇峰信号强度降低.此外,对样品浓度、信号强度与噪声的比值进行探讨,获得UV-FAIMS检测苯的检测限为0.011mg/m3.     

改性γ-Al2O3微填充柱色谱分析氢同位素

使用Cr2O3改性后的γ-Al2O3微填充色谱柱,分析了He、H2、HD、D2混合气体.结果表明,经改性后的γ-Al2O3柱对氢同位素分析的谱图在峰型、保留时间、柱效等方面明显优于未经改性的γ-Al2O3柱.在柱温77.4 K、氖载气流速30 mL/min、进样量5~100 μL条件下,氢同位素各组分线性关系良好,谱峰...