大体积进样技术在气相色谱-质谱法测定 二英类化合物中的应用

利用大体积进样技术(large volume injection,LVI),结合气相色谱-质谱方法对二英的测定效果进行了研究。同时与传统分流/不分流进样技术进行了对比。对进样体积为1,5,10,25,50和100 μL的色谱图进行了分析。研究表明使用大体积进样方式,在不影响色谱分离度的同时,大幅度提高了分析灵敏度。通过对土壤样品的检测,证明该方法可以用于环境样品的实际测定。     

填充毛细管液相色谱-高温毛细管气相色谱在线联用分析重油

重油的组成分析一直是个难题,它的沸点高,族组分种类多,各族内组分的异构体又极为繁多.最好的分析方法是用高效液相色谱(HPLC)做族分离,馏分收集后再用CGC分析.但HPLC的族馏分体积比CGC进样量大100倍.本文采用填充毛细管液相色谱(μHPLC)与高温毛细管气相色谱(HTGC)在线联用技术[1]分析重油.正相μHPLC将样品按族分离,μHPLC的柱效高,族分离能力强,而小的馏分体积(<100μL)可避免GC分流进样.在一次LC进样后,多位储存型联用接口将分离后的各族组分切割、存储并分别无损失转入HTGC分析,利用FID对高于C10的有机物的响应值相…     

通过柱切换技术与高效液相色谱联用的限进性柱对盐酸贝那普利的在线富集性能

以自制的限进性填料柱为预处理富集柱,Luna C₁₈柱为分析柱,通过柱切换技术将限进性填料柱与高效液相色谱联用(RAM-HPLC),研究了盐酸贝那普利的在线富集效果。考察了进样体积与峰面积、系统总压力的关系,以及常规进样与大体积进样的差别。当进样体积在100 μL以内时,峰面积随进样体积的增加而增加;当进样体积大于80 μL时,系统总压力变化明显。考虑对整个系统的保护,选择80 μL作为最大进样体积。同一浓度的样品进样20 μL与进样80 μL所得峰面积之间的线性关系良好。RAM柱对盐酸贝那普利具有良好的富集作用,能够有效提高HPLC的灵敏度,而且具有简单、经济的特点。     

微流量液相色谱在线大体积进样的方法和专用装置

本发明涉及微分离系统的进样方法,具体地说是一种微流量液相色谱在线大体积进样的方法和专用装置。在微流量液相色谱分离系统的流路中,添加多流路分流切换装置,使得系统在进样和分离时,流动相可以从不同流路分流。样品利用在固定相上的保留,实现色谱系统的大体积进样。     

在线凝胶色谱-气相质谱联用法同时快速测定全血样中10种有机磷

采用基于基质分散固相萃取原理的前处理结合在线凝胶色谱-气相质谱联用技术(GPC-GC/MS),建立了一种同时测定全血样中10种有机磷毒物的定量方法。全血样品经前处理后无需浓缩定容可直接进样,有效缩短前处理耗时,且GPC采用大体积进样模式,联用后相较于传统气质方法降低了检出限并且提高了灵敏度。优化的实验条件下,所有被测物均在0.5~5 mg/L范围内线性良好(R=0.9990~0.9999),检出限为2.2~15.4 mg/L(信噪比S/N=3),将空白加标连续进样6次,得到的色谱保留时间及峰面积相对标准偏差均小于3%,加标回收率为80.4%~111.7%。实验结果表明,该方法便捷快速,能够满足实际刑侦案件中有机磷毒物的检测需求。     

快速测量挥发性有机物的膜进样-飞行时间质谱仪的设计和应用

研制了一种膜进样-微型飞行时间质谱仪, 该仪器使用双层50 μm硅橡胶膜作为大气压下直接进样的接口. 实验结果表明, 随着样品流速的提高, 膜富集效率信号强度呈线性提高. 双膜中间具有真空差分系统, 富集得到的样品被迅速抽走, 进样系统中样品无记忆效应. 样品在膜中的响应时间为100 s, 而打开差分系统后仅需10 s信号即下降为平稳状态. 与毛细管直接进样相比, 双层膜的富集作用显著, 在相同的实验条件下使用膜进样技术测定10×10-6 (体积分数)苯、甲苯和对二甲苯的信号强度分别提高了280, 370和600倍. 膜进样系统与真空紫外光软电离方式联用, 对于苯的检出限已经达到了25×10-9 (体积分数), 线性范围为3个数量级. 由于采用了软电离方法, 无碎片离子产生, 所以能够根据分子量进行快速定性分析. 将该仪器应用于香烟主烟气中可挥发性有机物的在线分析, 得到50多种可挥发性的有机物. 实验结果表明, 膜进样-飞行时间质谱将在在线分析(特别是环境监测)方面具有广泛的应用空间.     

毛细管电泳进样技术新进展

评述了毛细管电泳进样技术新成果。对直接在线进样，二维分离体系中毛细管电泳分离的增样，相关毛细管电泳增样，超微量样品及单个分子的进样，近端进样，双向进样和高温下的进样装置的应用状况作了介绍。     

液相色谱-毛细管气相色谱/质谱离线联用分析烟草中的挥发性及半挥发性成分

建立了一种用于烟草样品中挥发性、半挥发性成分分析的液相色谱-毛细管气相色谱/质谱(LC-CGC/MS)离线联用方法。研究了LC-CGC/MS的分离机理。LC分析选用氨基分析柱(250 mm×2.0 mm, 5 μm)作为分析柱,正己烷-二氯甲烷-乙腈(90:6.6:3.4, v/v/v)作为流动相,对挥发性、半挥发性成分进行分离,收集得到5个馏分,并存放在5个氮吹瓶中。多次进样并收集相同时间段的馏分,氮吹浓缩至1 mL,然后分别进行CGC/MS分析,所用的CGC柱为DB-5MS(60 m×0.25 mm×0.25 μm)。结果显示,与直接采用CGC/MS分析相比,采用LC-CGC/MS分析复杂样本的效果更好,定性的可靠性更高。     

在线富集毛细管液相色谱法分析脂溶性维生素和β-胡萝卜素

以硅胶基质ODS整体柱为分离柱, 建立了毛细管液相色谱-紫外/可见光度法测定脂溶性维生素和β-胡萝卜素的方法. 对流动相组成、流速、样品溶解液和进样体积等参数进行了系统优化, 采用溶剂梯度区带压缩效应作为在线富集技术来提高检测灵敏度. 与传统的进样方式相比, 采用溶剂梯度区带压缩在线富集技术时, 在不损失分辨率的前提下, 可通过增大进样体积将脂溶性维生素和β-胡萝卜素的检测灵敏度提高34～60倍. 方法可用于检测玉米中的痕量维生素E.     

气相色谱可调样量进样技术

(一)气相色谱可调样量进样装置 气样在较低压力(本实验为1大气压)时,其样品数量关系可用气体状态方程描述: PV=nRT (1) 气相色谱进样系统中,人们使P,TV,恒定,从而实现定量进样。应用方便,广为使用。 但是,在需要变量进样的情况下就出现了新的问题。有人使P,T恒定,改变进样管体积V,达到改变进样量之目的。确实见到有人备有几只不同体积V的进样管,可是实际切换时颇多麻烦。 本实验技术为实施方便计,使V,T恒定,采用调控进样压力P的办法,达到可调样量变量进样之目的。     

Large volume injection techniques in capillary gas chromatography

Large volume injection (LVI) is a prerequisite of modern gas chromatographic (GC) analysis, especially when trace sample components have to be determined at very low concentration levels. Injection of larger than usual sample volumes increases sensitivity and/or reduces (or even eliminates) the need for extract concentration steps. Also, an LVI technique can serve as an interface for on-line connection of GC with a sample preparation step or with liquid chromatography. This article reviews the currently available LVI techniques, including basic approaches to their optimization and important real-world applications. The most common LVI methods are on-column and programmed temperature vaporization (PTV) in solvent split mode. Newer techniques discussed in this article include direct sample introduction (DSI), splitless overflow, at-column, and "through oven transfer adsorption desorption" (TOTAD).     

在线高效液相色谱-毛细管气相色谱联用方法的建立

建立了一种以保留间隙柱技术和阀切换以及定量管样品转移为接口并具有早期溶剂蒸气出口的在线液相色谱与毛细管气相色谱联用方法。考察了主要实验条件,如溶剂蒸发温度、载气压力等对联机系统性能的影响,并用萘和联苯对该系统的线性范围进行了测定。利用联机系统对一种轻柴油样品进行了分析。     

On-line introduction of high-pressure gas-liquid sample for capillary gas chromatographic analysis

An on-line sample introduction technique in capillary gas chromatograph (CGC) for the analysis of high-pressure gas-liquid mixtures has been designed and evaluated. A sample loop of 0.05 microL and a washing solvent loop of 0.5 microL are mounted on a 10-port switching valve, which serves as the injection valve. A capillary resistor was connected to the vent of sample loop in order to maintain the pressure of the sample. Both the sample and the washing solvent are transferred into the split-injection port through a narrow bore fused silica capillary inserted into the injection liner through a septum. The volume of the liner is used both as the pressure-release damper and evaporation chamber of the sample. On-line analysis of both reactants and resultants in ethylene olimer reaction mixture at 5 MPa was carried out, which demonstrated the applicability of the technique.     

Analysis of alkylbenzene samples by comprehensive capillary liquid chromatography x capillary gas chromatography

The constituents in synthetic alkylbenzene samples were analyzed by a comprehensive capillary liquid chromatography (micro-LC) x capillary gas chromatography (CGC). The micro-LC separates the mixture into aliphatic compounds, monosubstituted alkylbenzenes, multisubstituted alkylbenzenes and binuclear aromatic compounds. Each fraction from a single micro-LC injection is stored in turn in a multiloop interface, and then transferred online into CGC sequentially with large volume in-column splitless injection technique for detailed analysis. No sample discrimination was found with this coupling and injection technique. Both the micro-LC column dimension and transfer speed of fraction from interface to CGC were optimized. Quantitative results and the carbon number distribution of each chemical class are obtained by using the comprehensive micro-LC x CGC with flame ionization detection. The reproducibility of peak area is better than 2% RSD.     

Analysis of β‐blockers in groundwater using large‐volume injection coupled‐column reversed‐phase liquid chromatography with fluorescence detection and liquid chromatography time‐of‐flight mass spectrometry

Atenolol, nadolol, metoprolol, bisoprolol and betaxolol were simultaneously determined in groundwater samples by large‐volume injection coupled‐column reversed‐phase liquid chromatography with fluorescence detection (LVI‐LC‐LC‐FD) and liquid chromatography‐time‐of‐flight mass spectrometry (LC‐TOF‐MS). The LVI‐LC‐LC‐FD method combines analyte isolation, preconcentration and determination into a single step. Significant reductions in costs for sample pre‐treatment (solvent and solid phases for clean up) and method development times are also achieved. Using LC‐TOF‐MS, accurate mass measurements within 3 ppm error were obtained for all of the β‐blockers studied. Empirical formula information can be obtained by this method, allowing the unequivocal identification of the target compounds in the samples. To increase the sensitivity, a solid‐phase extraction step with Oasis MCX cartridge was carried out yielding recoveries of 79–114% (n=5) with RSD 2–7% for the LC‐TOF‐MS method. SPE gives a high purification of β‐blockers compared with the existing methods. A 100% methanol wash was allowed for these compounds with no loss of analytes. Limit of quantification was 1–7 ng/L for LVI‐LC‐LC‐FD and 0.25–5 ng/L for LC‐TOF‐MS. As a result of selective extraction and effective removal of coextractives, no matrix effect was observed in LVI‐LC‐LC‐FD and LC‐TOF‐MS analyses. The methods were applied to detect and quantify β‐blockers in groundwater samples of Almería (Spain).     

Selective and sensitive detection of organic contaminants in water samples by on-line trace enrichment–gas chromatography–mass spectrometry

Liquid chromatographic (LC) type trace enrichment is coupled online with capillary gas chromatography (GC) with mass spectrometric (MS) detection for the analysis of aqueous samples. A volume of 1–10 ml of an aqueous sample is preconcentrated on a trace-enrichment column packed with a polymeric stationary phase. After cleanup with HPLC-grade water the precolumn is dried with nitrogen and subsequently desorbed with ethyl acetate. A fraction of 60 μl is introduced on-line into a diphenyltetramethyldisilazane-deactivated retention gap under partially concurrent solvent evaporation conditions and using an early solvent vapor exit. The analytes are separated and detected by means of GC–MS. The potential of the LC–GC–MS system for monitoring organic pollutants in river and drinking water is studied. Target analysis is carried out with atrazine and simazine as model compounds; the detection limits achieved under full-scan and multiple ion detection conditions are 30 pg and 5 pg, respectively. Identification of unknown compounds (non-target analysis), is demonstrated using a river water sample spiked with 168 pollutants varying in polarity and volatility.     

Vaporising systems for large volume injection or on-line transfer into gas chromatography: Classification, critical remarks and suggestions

Techniques for large volume introduction of liquid samples into capillary gas chromatography (GC) follow a small number of principals. Vaporising systems, vapour discharge modes and methods for solvent-solute separation are classified and evaluated.

Presently, programmed temperature vaporising (PTV) solvent split injection is the preferred method if on-column techniques cannot be applied. Critical re-evaluation suggests, however, that solvent evaporation and solvent-solute separation should be performed in separate compartments and optimized individually. Permanently hot chambers offer the highest capacity for solvent evaporation. The preferred techniques for solvent-solute separation are stationary phase focusing in a coated capillary or solvent trapping in an uncoated capillary precolumn. The vaporising chamber-precolumn solvent split-gas discharge system is proposed for large volume injection and on-line transfer of water-containing solvent mixtures, and in-line vaporiser-precolumn solvent split-overflow system for most on-line transfer applications.     

Determination of polynuclear aromatic hydrocarbons in water samples using large volume on-column injection capillary gas chromatography

An automated large volume on-column injection technique for capillary gas chromatography (GC) with solvent divert and heated retention gap technology has been utilized to determine polynuclear aromatic hydrocarbons (PAHs) in samples of industrial plant process water. Injecting large sample volumes on-column enabled the sample preparation procedure to be simplified and provided a fast, labor-saving technique for screening water samples. Diverting approximately 95% of the solvent away from the analytical column and the detector enabled chromatography to reflect classical capillary loading and detector conditions. Simplifications include significant reduction of sample and eluent volumes used during extraction and the elimination of Kuderna-Danish evaporative concentration. System performance, such as linearity and limit of detection, were evaluated for selected PAHs. Spiked water samples were prepared in the lower μ/L range to determine extraction efficiency. Results are compared with those obtained by a reputable contract laboratory following EPA Method 625.     

Analysis of turkish lignite tar by coupled LC/GC,GC/MS,and capillary SFC

This work describes the analysis of a pyrolysis product of a lignite sample obtained from the Turkish Goynuk reserve. The aliphatic, aromatic and polar compounds present in the tar are separated and identified by various chromatographic techniques: Capillary gas chromatography/mass spectrometry (GC/MS), on-line high performance microbore liquid chromatography/capillary gas chromatography (LC/GC) and capillary supercritical fluid chromatography (SFC). The suitability of each technique for this particular application is discussed, and semi-quantitative results are presented for the major components detected.