脉冲放电氦光离子化检测器分析有机化合物的性能研究

研究本实验室组装的脉冲放电氦光离子化检测系统上PDPID的性能、各种操作参数对信号的影响、操作最佳化及信号线性。用该系统分析了汽油、酮醇混合物和痕量挥发性有机化合物等样品,它们的色谱图可以同FID相比。     

Determination of Xenon in Air by a Pulse-discharge Helium Ionization Detector

A pulse-discharge helium ionization detector(Valco, PD-D3-I) was used to measure xenon concentration in air. The dependences of the detector relative response on various gas chromatograph parameters were investigated. Based on the well prepared gas connections for the detector system and optimized gas chromatography(GC) working conditions, the atmospheric xenon concentration could be measured by the cheap GC method with a detection level of 0.7?0^-9(parts by volume). Moreover, the xenon concentration in the ground level air around our laboratory was measured with the result of 0.085?0^-6(parts by volume) and RSD of 0.91%.     

在线气体分析的电晕放电大气压电离质谱

研制了适合在线气体分析的电晕放电大气压电离源(corona discharge atmospheric pressure ionization source)及其与商品质谱仪(LTQ-MS)的接口,对其试剂离子的产生机理进行了研究,以H2O. (H2O)为试剂离子,对乙醇气体进行检测,并分析了该离子的产生机制。实验结果表明:在潮湿氮气中电晕放电产生的主要试剂离子是m/z36、37和55;而在含丙酮的潮湿氮气中则产生m/z59和76等离子。利用静态顶空-电晕放电大气压电离质谱对不同浓度的乙醇水溶液进行分析,结果表明:以m/z64为检测对象,乙醇气体浓度的最低检出限可达2.4×10-7g/L;而以m/z47为检测对象,检出限为5.9×10-6g/L。同时还利用动态顶空-电晕放电大气压电离质谱对栀子花香气成分进行了检测,为生物挥发性物质的在线检测提供了一种新方法。     

The Performance of a Dual Alkali Aerosol Flame Ionization Detector for Gas Chromatography

Abstract

The described alkali flame ionization detector (AFID) differs from other designs by introducing the alkali salt into the detector in the form of an aerosol. The preheated, desolvated alkali aerosol salt is introduced into a dual hydrogen gas flame assembly. This detector shows no evidence of fatigue due to the constant delivery of salt into the detector, compared to the fixed alkali supply found in other versions, which can be depleted by vaporization and become easily contaminated. This AFID design also allows for operation as an FID by implementing a simple pneumatic procedure. This paper deals with the performance and optimization of the detector using a dual alkali salt aerosol flame design for organonitrogen and organophosphorus compounds. Detection limits were 23.5 pgN/sec for alachlor, 185 pgN/sec for dinoseb, and 4.83 pgP/sec to 10.1 pgP/sec for various pesticides studied. Selectivity ratios are tunable to 6.6 × 10⁶ gP/gC, 4.0 × 10⁴ gN/gC and 2.3 × 10³ gP/gN by establishing the appropriate detector gas flow rates.     

The Gas Chromatographic Separation of Volatile Fluorides Using a Hydrogen Diffusion Flame as Detector

Abstract

An account is given of the preparation, separation and detection of volatile fluorides. These fluorides are formed by the reaction of chlorine trifluoride with the elements in a specially designed PTFE reaction vessel enclosed in an HF coil. A comparison is also made of a spectroscopic detector with a katharometer for the detection of the fluorides.

The separation of volatile fluorides has been reported to be partially successful on perfluorinated materials such as Kel-F oils or waxes on PTFE supports.^1–3 The present communication describes a more detailed investigation of these separations and also compares the performance of a newly developed spectroscopic detector⁴ with a conventional katharometer detector.     

用于负压下气体分析的气相色谱仪的研制

介绍一种可同时分析负压样品中常量Ｏ２,Ｎ２,ＣＯ和微量ＣＯ２的自制专用气相色谱仪。仪器在 负压下取样,经活塞升压后进样。在流程中样品气同时进入并列的色谱柱,再分别检测。常量组分使用热导池检测,微量组分使用氦离子化检测器检测。ＣＯ２的检测灵敏度为１０＾－６量级。实验表明,仪器结构简单,操作方便稳定性好,适合于负压气样的在线分析,负压气样中全组分的分析方法具有推广价值。     

Tunable Selectivity of an Alkali Aerosol Flame Ionization Detector Towards Organobromine and Organoiodide Species for Gas Chromatography

Abstract

The performance of a halogen selective aerosol alkali flame ionization detector (AFID) is presented. A constant delivery of desolvated alkali salt aerosol is introduced into the detector in the form of dual hydrogen gas flames. The problems of enhancement-source vaporization and contamination, which occur in fixed alkali salt versions, do not occur with the presented aerosol design. Detection limits range from 321 pgI/sec to 450 pgI/sec and 6.7 ngBr/sec to 15 ngBr/sec. Selectivity ratios were 10³ gI/gC and 10² gBr/gC using an 100 ppm potassium chloride as the alkali salt solution.     

利用回归分析研究火焰离子化检测器相对响应值

以乙酸乙酯对正庚烷的相对摩尔响应值（Ｓ＿Ｍ）为例，研究了Ｎ＿２，Ｈ＿２流速对Ｓ＿Ｍ的影响，得到了回归方程并求得了最佳操作条件。     

Low-Cost Detection of Methane Gas in Rice Cultivation by Gas Chromatography-Flame Ionization Detector Based on Manual Injection and Split Pattern

Rice cultivation is one of the most significant human-created sources of methane gas. How to accurately measure the methane concentration produced by rice cultivation has become a major problem. The price of the automatic gas sampler used as a national standard for methane detection (HJ 38-2017) is higher than that of gas chromatography, which greatly increases the difficulty of methane detection in the laboratory. This study established a novel methane detection method based on manual injection and split pattern by changing the parameters of the national standard method without adding any additional automatic gas samplers. The standard curve and correlation coefficient obtained from the parallel determination of methane standard gas were y = 2.4192x + 0.1294 and 0.9998, respectively. Relative standard deviation (RSD, <2.82%), recycle rate (99.67–102.02%), limit of detection (LOD, 0.0567 ppm) and limit of quantification (LOQ, 0.189 ppm) of this manual injection method are satisfying, demonstrating that a gas chromatography-flame ionization detector (GC-FID), based on manual injection at a split ratio (SR) of 5:1, could be an effective and accurate method for methane detection. Methane gases produced by three kinds of low-methane rice treated with oxantel pamoate acid, fumaric acid and alcohol, were also collected and detected using the proposed manual injection approach Good peak shapes were obtained, indicating that this approach could also be used for quantification of methane concentration.     

Membrane Extraction of Volatile Organic Compounds in Combination with Mobile Gas Chromatographic Analysis

Abstract

The field of application of a mobile gas chromatographic device (Airmobtx monitor HC 1000 manufactured by Airmotec GmbH) originally conceived for the analysis of BTEX in air was extended to water analysis by using it in conjunction with membrane extraction. Volatile organic compounds diffuse out of water through a hollow fibre or flat membrane, are enriched onto sorption tubes integrated in the device, and then thermally desorbed and analysed by the gas chromatograph/flame ionisation detector. The suitability of various flat membranes and hollow fibres was investigated. Maximum extraction efficiency was obtained with a silicone hollow fibre measuring 0.3 m long, and with an inner diameter of 0.7 mm and a wall thickness of 100 μm. The extraction parameters were optimised. The linear dynamic range of the optimised method spans two orders of magnitude and the detection limits were found to be 0.1 μg/L for all BTEX compounds. By way of environmental applications, highly contaminated groundwater samples were analysed. The results correspond well to those achieved using conventional headspace/gas chromatography/flame ionisation detection.     

Development of a Piezoelectric Crystal Sorption Detector for Monitoring of Total Organic Compounds in Air

Abstract

A light and portable organic vapours monitor has been developed using piezoelectric (P/Z) quartz crystal to determine Volatile Organic Compounds (VOCs) commonly found in workplace air. Out of the eight coating material studied, High Vacuum Grease (HVG) was found to be the best for determining commonly encountered organic vapours such as 1,1,1-Trichloroethane, Chloroform, Benzene and Toluene in room air. The optimised coating weight was 23 μg HVG at a flow rate of 200 mL/min. Moisture was found to interfere and the use of a Nafion gas dryer was found to reduce the relative humidity to a constant 37 % for room air with 43–81 % relative humidity. Under optimised conditions, a mean sensitivity of 1.9 × 1^?2 Hz/ppm was obtained for total VOCs with 17.2% RSD variation towards different VOCs. Excellent linear working ranges were obtained from 40 to 2400 ppm (v/v), with response time and recovery time within one minute up to 500 ppm (v/v) of analyte. High and relatively constant response factors were obtained for different VOCs. The reliability of the mcthod has been established by parallel method comparison using established GC-FID method. The P/Z detector developed could also be used to monitor individual VOCs.     

大气压化学萃取电离质谱法用于吡啶类化合物的快速检测

利用大气压化学萃取电离源质谱技术(EAPCI-MS)对吡啶类化合物的电离行为特征进行研究。实验显示,EAPCI-MS技术在常温常压条件下,无需样品预处理和任何辅助化学试剂,在质谱图中能同时检测到吡啶类化合物的质子化分子离子峰[M+H]+和分子离子峰M+·,并具有类似的二级碎裂机理。研究结果表明,EAPCI-MS技术具有不同于传统电离源质谱的裂解方式,同时兼具传统电喷雾电离(ESI)和大气压化学电离(APCI)的特征电离方式和行为,极大地提高了化学检测的选择性,增强了质谱分析的定性能力。该研究为吡啶类化合物的检测和鉴定提供了一种新方法,对吡啶类化合物的快速检测具有重要的应用价值和意义。     

基于微机电系统技术的微型气相色谱检测器在测定白酒微量乙酸乙酯中的应用

本文构建了一种新型的用于微型化气相色谱的热导检测器(TCD)。在优化的色谱条件下测定了白酒中微量乙酸乙酯的含量。TCD检测器的测定结果与商用火焰离子化检测器(FID)的测定结果一致。     

光纤原料四氯化硅中微量三氯氢硅的气相色谱分析

采用石英毛细管柱与氩检测器相联结的气相色谱方法定量检测高纯的光纤原料四氯化硅中微量三氯氢硅等含氢杂质。该方法简单、可靠,三氯氢硅的检测下限达０．１×１０￣（－６）Ｗ／Ｗ。     

色谱/原子吸收联用系统中卧管式微火焰原子化离子化同步检测器的研究与应用

 介绍了一种新型的卧管式微火焰原子化离子化同步检测器 ,对其结构、工作原理及性能进行了研究。将其应用到色谱 /原子吸收联用系统中 ,实现了有机金属化合物以及与其共存的有机化合物的同步检测。有机金属化合物 (二乙基汞 )的原子吸收信号检出限为 2 5× 10 -11g/s;有机化合物 (苯 )的离子化信号检出限为 1 0× 10 -11g/s。     

Studies on the Use of Commercial Capillary Gas Chromatographic Columns as Diffusion Denuders

The possibility of using a piece of gas chromatographic capillary column as a tubular denuder for isolation and enrichment of organic pollutants present in air was studied. The partition coefficients (K_fs) of typical organic pollutants (benzene, chlorobenzene, toluene) between the gaseous phase and the denuder sorption layer were determined and effects of analyte concentration in the gaseous phase and gas flow rate on partitioning were studied. The partition coefficients were found to be constant in the studied range of concentration and gaseous mixture flow rate. A piece of a capillary column coated with polydimethylosiloxane can be used as a tubular denuder.     

真空紫外光电离质谱技术进展及其在快速分析中的应用

真空紫外光电离源(VUV-PI)是一种普适性的质谱软电离源,真空紫外光电离质谱谱图无碎片、易解析、灵敏度高,适合于在线快速分析.真空紫外光电离质谱根据分析对象不同可以直接采用单光子电离或添加掺杂剂实现化学电离,能实现气、液、固体分析,也可实现成像分析.该文介绍了真空紫外光电离源的电离原理、光源类型,分析了光电离质谱灵敏...     

Gas Liquid Chromatographic Determination of Promethazine Hydrochloride in Polyethylene Glycol Suppositories Using the Hall's Electrolytic Conductivity Detector

Abstract

A gas liquid chromatographic method using the Hall's electrolytic conductivity detector is described for the determination of promethazine hydrochloride in polyethylene glycol suppositories. This method is capable of distinguishing the intact drug from its thermal degradation products. A linear relationship between peak height ratio (promethazine/promazine) and promethazine hydrochloride concentration is found up to a concentration of 600 μg/ml. In the presence and absence of polyethylene glycol vehicle the recovery of promethazine hydrochloride is found to be 100.2 and 99.7 percent respectively. The percent coefficient of variation is 0.62 and 0.94 in the absence and presence of polyethylene glycol vehicle.     

Non-Targeted Screening Approaches for Profiling of Volatile Organic Compounds Based on Gas Chromatography-Ion Mobility Spectroscopy (GC-IMS) and Machine Learning

Due to its high sensitivity and resolving power, gas chromatography-ion mobility spectrometry (GC-IMS) is a powerful technique for the separation and sensitive detection of volatile organic compounds. It is a robust and easy-to-handle technique, which has recently gained attention for non-targeted screening (NTS) approaches. In this article, the general working principles of GC-IMS are presented. Next, the workflow for NTS using GC-IMS is described, including data acquisition, data processing and model building, model interpretation and complementary data analysis. A detailed overview of recent studies for NTS using GC-IMS is included, including several examples which have demonstrated GC-IMS to be an effective technique for various classification and quantification tasks. Lastly, a comparison of targeted and non-targeted strategies using GC-IMS are provided, highlighting the potential of GC-IMS in combination with NTS.