A different operational mode for addressing the general elution problem in rapid analysis gas chromatography

The task of chromatographically separating a complex mixture containing constituents with a wide range of molecular weight has been referred to in the past as the “general elution problem”. A different operational mode for conducting gas chromatography, thermal gradient programmed gas chromatography, presently in the developmental stage, has been investigated and is proposed as a means whereby such separations might be accomplished rapidly. The inherent versatility of the technique for conducting rapid analyses (50 to 300 s duration) of complicated samples containing constituents with a wide range of volatility is considered in terms of the possibility of achieving the maximum amount of analytical information per unit time.     

气相色谱法探究聚醚醚酮的热降解及热氧化降解（英文）

Poly(ether ether ketone)(PEEK)was synthesized via polycondensation of hydroquinone with 4,4′-difluorobenzophenone at 320℃for 5 h.Thermal and thermo-oxidative degradation of PEEK was studied over a wide range of temperatures.In an inert medium,decomposition of the polymer occurred in one stage,with the formation of a coke residue accounting for approximately 50%of the original polymer mass.In air,the mass loss curve exhibited two distinct stages.The first stage involved breakdown of the main polymer chain,the speed of which indicated a radical chain failure mechanism.In the second stage,the rate of mass loss clearly decreased,indicating a transition from the radical chain failure mechanism to simple combustion reactions(wherein the polymer combusted completely).To further investigate the nature of the processes occurring during the pyrolysis of PEEK,the investigations were carried out using gas chromatograph under isothermal conditions.It was concluded that during thermal degradation,the decomposition of the polymer starts with the rupture of ketone and ether bonds and proceeds to destruction of the benzene ring at higher temperatures,which is accompanied by the formation of H2O and CH4.Above 500℃,the polymer degradation further involved thermohydrolysis.The thermo-oxidation of PEEK,which was accompanied mainly by the formation ofH2,was noticeable beginning at 325℃.The total yield of the latter indicated oxidation of fragments of the benzene ring.     

供气相色谱仪使用的热导检测器的设计与实现

为了提高气相色谱仪用热导检测器的性能,设计了热导检测器的精密恒流源和差压检测电路。恒流源由场效应管IRF460、运算放大器AD8672和线性光耦HCNR201构成,低噪声电桥差压检测电路由2片AD8597构成。建立了差压检测电路的噪声模型,计算了噪声理论值。实际测试结果表明,该热导检测器的基线噪声达到4 μV, 50 min的基线漂移为15 μV,恒流源波动接近1 μA,优于现有热导检测器的技术指标。所介绍的设计方案和噪声分析方法对热导检测器的电路设计有较大的参考价值。     

Direct analysis of polychlorinated biphenyls in heavily contaminated soils by thermal desorption/gas chromatography/mass spectrometry

A robust analytical method is presented for the direct determination of polychlorinated biphenyls in soil samples by thermal desorption/gas chromatography/mass spectrometry. The method is simple to perform (thermal desorption and analysis are performed in-line employing a limited amount of sample, 2?mg) and eliminates the need for any solvent and time-consuming extraction. The analytical procedure was optimized using a soil sample spiked with Aroclor 1254 and Aroclor 1260 and validated with a certified industrial soil sample for which the concentration of thirteen PCB congeners are known. Limits of detection were sensitive to matrix effects and varied substantially among analytes. The matrix effect resulted in a reduction of the limits of detection by 1.5–10 times. However, it was found that the matrix effect is not due to ion suppression but to the increase of the noise of selected ion monitoring (SIM) traces, indicating that no limitation exists with using a single surrogate standard. By employing a 13C-labelled PCB internal standard, limits of detection in the range of 0.8 to 10?µg?g^?1 of soil were obtained. The obtained experimental results demonstrated that the proposed analytical method can be conveniently applied for screening a large number of heavily contaminated soil samples thus avoiding the employment of harmful solvents and time-consuming extraction procedures.     

Characterization of polymers by multi-step thermal desorption/programmed pyrolysis gas chromatography using a high temperature PTV injector

Thermal treatment hyphenated with gas chromatography is a versatile and powerful tool in the study of polymer characterization. An inexpensive system where thermal treatment at different temperatures occurs inside a Programmable Temperature Vaporization injector (PTV) is described. The samples investigated, commercial plastics, are complex mixtures that contain several polymers and additives. These plastics as well as their pure constituents are subjected to multi-step thermal treatment. The individual chromatograms of the various constituents of the polymeric sample are correlated with those of the final material in order to identify additives (thermal desorption) and degradation products (pyrolysis). Results obtained with the new method indicate the interesting potentials of the technique for the characterization of polymer compositions. Reproducibility of absolute and relative peak areas has been considered and found to be acceptable. The absence of a heated transfer line and switching valves, which are always present in conventional set-ups, eliminates the risk of losses of high molecular weight components. Further advantages of the technique proposed are simplicity, versatility, and its inexpensive nature.     

微型气相色谱仪热导检测器放大电路设计

Agilent公司生产的Agilent 3000+系列色谱仪是微型气相色谱仪(micro GC)的典型代表,其热导检测器的信号放大电路和模数转换器(analog-to-digital convertor, ADC)存在功耗大、工作温度过高等不足.文中分析了micro GC电路的功能需求,从选用低噪声的24 bit Δ-Σ ADC ADS1255入手,设计了高共模电压容限、低噪声的全差分放大电路及其他外围电路,并且对全差分放大电路建立了噪声模型,计算了其噪声理论值,优化了系统设计参数.另外,还设计了一个测试平台,对所设计的全差分放大电路和ADC的性能进行了全面的测试评估,结果表明新设计的热导检测器放大电路与ADC的总噪声(以美国材料与试验协会(ASTM)标准值计)仅为1.25 μV,总功耗降低了3.7 W,满足micro GC的功能需求,而且可靠性高、体积小、结构简单,可用于新一代micro GC的研发和生产.     

3,4-二(3-苯氧基-4-氟苯基)-2,5-二苯基苯基接枝聚硅氧烷气相色谱固定相的合成与表征（英文）

合成了一种耐高温的3,4-二(3-苯氧基-4-氟苯基)-2,5-二苯基苯基接枝聚硅氧烷(DPFP)固定相,使用静态涂渍法将其涂渍到毛细管柱内壁上,制成气相色谱柱。分离裂解乙烯的色谱图显示DPFP固定相在360℃时仍具有良好的分离能力。DPFP固定相的柱效为3 324块/米(保留因子(k)4.24,萘,0.25 mm i.d.)。麦克雷诺常数计算结果显示DPFP固定相属中等极性。溶剂化参数模型结果显示DPFP固定相与溶质之间的主要作用力为偶极-诱导偶极作用力、氢键碱性作用力。Grob试剂分离结果显示DPFP色谱柱具有良好的选择性与惰性。另外,芳香族同分异构体、苯取代物、多环芳烃、脂肪酸酯及脂肪醇都得到了良好的分离,表明DPFP固定相在应用方面有巨大的潜力。     

程序升温汽化大体积进样气相色谱法同时测定空气中的甲醛及其他10种羰基污染物（英文）

Long-term indoor-air limit for formaldehyde stipulated by the European Commission is 1 μg/m3,while the World Health Organization has set a threshold of 100 μg/m3 that should not be exceeded for more than 30 min. To date,however,only a few analytical techniques have been developed that can be used to detect formaldehyde at these very restrictive limits. Thus,there is a need to develop for comprehensive methods for analyzing airborne formaldehyde and other carbonyl pollutants in the ambient environment. The aim of this study is to develop a highly sensitive online automated preconcentration gas chromatographic method using large-volume injection with a programmed temperature vaporization injector for the analysis of airborne formaldehyde and ten other carbonyl compounds. The influence of several parameters,such as the maximum volume injected,programmed temperature vaporization transfer time and temperature,carrier gas flow rate,and type of packing material was investigated. After optimization,highly satisfactory results in terms of the absolute and methodological detection limits were achieved,i. e. as low as the μg/m3 level for all the carbonyl pollutants studied. A commercially available sampler,originally designed for active sampling,was evaluated as a passive sampling device;this optimized technique was applied to monitor the concentrations of carbonyl pollutants in the indoor air of ten public buildings in Florence. The strength of this methodology lies both in the low detection limits reached in the simultaneous analysis of a wide group of 2,4-dinitrophenylhydrazine derivatives,and the potential adaptability of this method to other gas chromatographic applications to achieve lower sensitivity.     

气相色谱法分析甘蓝及其土壤中的烯啶虫胺残留

建立了气相色谱测定甘蓝植株和土壤中烯啶虫胺残留量的分析方法。样品采用丙酮-水(4:1, v/v)进行提取,经弗罗里硅土柱净化,用电子捕获检测器进行测定。实验结果表明,添加水平为0.02～2.00 mg/kg时,烯啶虫胺在甘蓝植株和土壤中的平均回收率分别为88.73%～94.13%和90.82%～96.27%,相对标准偏差分别为3.09%～7.39%和2.01%～4.92%;方法的最低检出限为0.02 mg/kg。该方法快速简便、灵敏度高、重现性好,可用于环境系统中烯啶虫胺残留量的检测分析。     

全二维气相色谱在石油地质样品分析中的应用进展

对石油地质样品的化学组成进行全面准确的剖析,可以获得丰富的地球化学信息,为油气勘探工作提供科学依据。然而,该类样品除了组成复杂之外,还易受到各种物理（如蒸发、乳化、扩散、溶解和吸附）、化学（如光降解）和生物（如微生物降解）过程的影响。这些特点给样品的分析研究工作带来了极大的困难,传统的一维气相色谱/质谱技术很难对其进行理想的分离。全二维气相色谱（GC×GC）作为新发展起来的一种分离技术,在复杂样品分析方面具有独特的优势,虽然在石油地质样品分析中的应用相对较晚,但也日益受到关注。本文主要综述了近5年来GC×GC在石油地质方面国内外的研究进展以及存在的主要问题,并对今后的研究进行了展望。     

气相色谱分析农药残留的基质效应及其解决方法

对于相同浓度的农药,其在基质溶液中的色谱响应会比其在纯溶剂中的响应高。通过减少热不稳定农药的分解,以及屏蔽进样口的活性位点而减少极性农药在活性位点的吸附或分解,基质效应可增加从进样口传输到色谱柱中的农药残留量。各种进样方式和基质净化方法都可以减少但不能完全消除基质效应;基质匹配校准法和分析保护剂法是避免基质效应最有效的方法;在实际检测中,所采用的消除或补偿基质效应的方法应考虑减少仪器系统的维护。本文概述了农药残留分析检测中的基质效应及其解决方法。     

气相色谱分析柑橘类水果中残留的苯丁锡

建立了气相色谱-火焰光度检测器测定柑橘类水果中苯丁锡残留量的检测方法。样品在酸性条件下经丙酮及正己烷萃取并浓缩,用正己烷溶解残渣,经乙基溴化镁衍生后,采用硅胶固相萃取柱净化,正己烷-二氯甲烷(体积比为4:1)混合液洗脱,用毛细管气相色谱-火焰光度检测器(锡滤光片: 610 nm)测定,外标法定量。结果表明: 该方法的线性范围为0.2～2.0 mg/L,相关系数r≥0.9995;当阴性脐橙样品中加标水平为0.1～0.4 mg/kg时,苯丁锡的回收率为79.6%～109.6%,相对标准偏差为3.60%～9.05%,方法的检出限为0.1 mg/kg。该方法重复性好,灵敏度高,完全满足国内外柑橘类水果中苯丁锡残留分析的要求。     

气相色谱法检测工业用乙二醇纯度及杂质

以Rtx-624色谱柱（30 m×0.32 mm×1.8 μm）为分析柱进行分析，采用校正面积归一化法，建立了检测工业用乙二醇纯度及其中有机杂质的气相色谱分析法。该法可检测传统乙烯法制得的乙二醇中固有杂质二乙二醇、三乙二醇和1，3-二氧杂烷-2-甲醇，同时也适用于检测草酸酯加氢法制得的乙二醇中的新杂质（1，2-丁二醇、1，4-丁二醇、1，2-己二醇、碳酸乙烯酯等）。结果表明，该法具有良好的重复性和较高的检测灵敏度，检出限最低可达0.0002%（质量分数），回收率在91.2%~105.4%之间。该法在乙二醇生产控制、产品检测、市场贸易等过程中具有良好的应用前景。     

溶剂转移-气相色谱-质谱法和选择洗脱-气相色谱法测定大蒜中289种农药多残留

以溶剂转移净化为核心步骤,建立了一种适用于大蒜样品中农药多残留分析的前处理方法(方法I),配以一个辅助方法(方法II),构成大蒜中常见289种农药多残留的分析体系(方法I283种,方法II6种)。方法I中,样品用乙腈-水溶液提取,盐析分配,溶剂转移和固相萃取(SPE)净化后进行气相色谱-质谱(GC-MS)分析;方法II中,样品用无水Na2SO4配合乙酸乙酯均质研磨,超声波辅助提取,提取液经Primary Secondary Amine (PSA)粉末分散固相萃取和LC-Si柱选择洗脱净化后进行GC分析。GC-MS采用选择离子监测(SIM)方式,GC采用火焰光度检测器(FPD)检测,外标法定量。方法简便、快速,通过优化前处理和上机条件,在最优条件下进行测试,方法的定量限(S/N≥10)为0.01～0.05 mg/kg。方法I中,在加标水平为0.02、0.20 mg/kg时,回收率为52%～163%,其中回收率在70%～120%之间的占88%,相对标准偏差为2.4%～18%;方法II中,在加标水平为0.01、0.02、0.10、0.20 mg/kg时,回收率为70%～111%,相对标准偏差为3.2%～9.3%。详细描述了实验模型的构建,并对GC-MS灵敏度的提高提出了新的见解。该方法准确、灵敏、快速,可满足大蒜中多种农药残留的检测要求。     

全二维气相色谱分析持久性有机污染物的应用进展

持久性有机污染物（POPs）组分复杂,在自然界中超痕量存在,其分离分析十分困难。全二维气相色谱（GC×GC）作为一种新型色谱技术,与传统的一维气相色谱相比,具有峰容量大、分辨率和灵敏度高等优势,越来越广泛地应用于环境有机污染物的分析。该文综述了近十年来全二维气相色谱在持久性有机污染物分析中的应用进展,主要包括全二维气相色谱在解决一些复杂POPs定性定量分析难题方面的应用,如二恶英、毒杀芬和短链氯化石蜡等;概述了全二维气相色谱对多种POPs同时定性定量分析的应用进展;讨论了全二维气相色谱在非目标有机污染物筛查分析中的应用,并对发展趋势及相关应用前景进行了总结展望。     

气相色谱法测定茶叶及土壤中的高效氯氟氰菊酯残留量

建立了气相色谱测定茶叶及土壤中高效氯氟氰菊酯残留量的分析方法。茶叶和土壤样品用正己烷提取,毛细管柱分离,气相色谱-电子捕获检测器(GC-ECD)检测。结果表明: 在高效氯氟氰菊酯添加量为0.02～2.00 mg/kg范围内,高效氯氟氰菊酯在鲜茶叶和土壤中的平均添加回收率分别为89.0%～94.1%和89.8%～94.7%,相对标准偏差(RSD, n=5)分别为3.0%～4.9%和2.5%～4.2%,方法的最低检出限(S/N=3)为0.002 mg/kg。采用该方法测定2.5%高效氯氟氰菊酯微乳剂在湖南长沙茶叶及土壤中的消解动态,其符合一级动力学消解模式,消解方程分别为y=3.1996e-0.3394x和y=0.1224e-0.1036x,相关系数分别为0.9956和0.9247。在茶叶中的半衰期为2.04 d,在土壤中的半衰期为6.69 d。该方法为湖南长沙地区茶叶种植科学合理地使用杀虫剂高效氯氟氰菊酯提供了依据。     

样品前处理技术在气相色谱分析中的应用进展

气相色谱法是当前应用最广泛的分析技术之一。使用气相色谱对复杂基体进行分析时的样品前处理步骤往往繁琐耗时,易引起误差,已成为制约分析效率和准确度提升的关键环节。本文综述了2009-2013年几种主要的样品前处理技术,包括吹扫捕集、固相萃取、固相微萃取、液相微萃取技术以及微波辅助萃取、超声波辅助萃取等场辅助萃取技术在气相色谱分析中的应用研究进展。     

气相色谱法测定苹果和土壤中的高效氯氟氰菊酯

建立了改进的QuEChERS-气相色谱检测苹果和土壤中高效氯氟氰菊酯残留的分析方法,考察和评价了苹果和土壤两种基质对高效氯氟氰菊酯的基质效应。苹果和土壤样品均用乙腈提取,经石墨化碳黑（GCB）净化后直接进样分析。结果表明：在优化后的QuEChERS条件下,高效氯氟氰菊酯在0.05~10 mg/L范围内线性关系良好,相关系数（R²）大于0.999,检出限为0.12~0.15 μg/kg,定量限为0.38~0.50 μg/kg。用基质标准曲线定量时,高效氯氟氰菊酯在土壤和苹果中的回收率分别为88.29%~97.65%和80.70%~98.69%。苹果和土壤样品对高效氯氟氰菊酯都表现出基质增强效应。该方法的回收率均能达到残留分析要求,用基质配制标准溶液能够有效、方便地校正气相色谱-电子捕获检测器测定高效氯氟氰菊酯残留时的基质效应,且能应用于苹果和土壤实际样品的检测。     

气相色谱法测定中华绒螯蟹中脂肪酸组成与含量

中华绒螯蟹中脂肪酸组成与含量的测定对评估其营养价值与品质具有重要意义,但面对种类繁多的脂肪酸提取试剂和甲酯化试剂,测定结果参差不齐,很难对中华绒螯蟹中丰富的脂肪酸准确定量。研究通过比较4种常见的脂肪提取试剂、2种脂肪酸甲酯化试剂,确定以氯仿-甲醇(1∶1, v/v)为提取试剂,含2%硫酸的甲醇溶液为甲酯化试剂,建立了测定中华绒螯蟹肌肉中脂肪酸组成与含量的气相色谱分析方法。实验按照程序升温的条件,采用DM-2560毛细管色谱柱(100 m×0.25 mm×0.20 μm)分离37种脂肪酸,氢火焰离子化检测器(FID)检测,外标法定量。37种脂肪酸在0.5~100.0 μg/mL范围内线性关系良好,其相关系数(R²)为0.9981~0.9999,检出限(LOD)与定量限(LOQ)分别为0.01~0.02 mg/100 g和0.04~0.06 mg/100 g;以棕榈酸和硬脂酸进行加标回收验证,在1、2、10 mg/100 g 3个加标水平下的加标回收率为76.0%~97.5%,相对标准偏差(RSD, n=5)为3.31%~7.90%。该方法应用于中华绒螯蟹肌肉中脂肪酸组成与含量的测定,肌肉中共测得31种脂肪酸,碳链长度为12~24,脂肪酸总含量为281.03 mg/100 g,其中油酸、二十二碳六烯酸、二十碳五烯酸等为中华绒螯蟹肌肉中主要脂肪酸。该方法操作简便,试剂、样品用量少,且定性可靠,定量准确,能检测较多的脂肪酸种类,适用于中华绒螯蟹肌肉中脂肪酸组成与含量的快速检测。     

聚二乙烯苯整体柱的制备及其在气相色谱分析中的应用

初步探讨了毛细管整体柱的制备方法及其在气相色谱分析中的应用。以液相色谱用毛细管整体柱作为研究基础,通过改变甲苯和十二醇的比例,使整体柱适用于气相色谱分析。通过二乙烯苯与键合在管壁上的3-(异丁烯酰氯)丙基三甲氧基硅烷(TMP)键合以及其自身的聚合,获得具有牢固结构、良好机械强度的整体柱。将其用于混合溶剂的分析和白酒标样的分析,可直接分析水中低碳醇。与现有的商品柱进行比较,结果表明所制备的整体柱均优于用以对照的商品色谱柱,其中在混合溶剂的分析中,醇类、酯类、酮类和芳烃类的峰形均优于用于比较的多孔层开口管(PLOT)柱;在白酒标样分析中,使得乙醛、甲醇、乙酸乙酯的色谱峰能够分开,比现有的聚乙二醇(PEG-20M)柱的分析方法更为便捷。