Fast Capillary Gas Chromatography: Comparison of Different Approaches

Savings in analysis time in capillary GC have always been an important issue for chromatographers since the introduction of capillary columns by Golay in 1958. In laboratories where gas chromatographic techniques are routinely applied as an analytical technique, every reduction of analysis time, without significant loss of resolution, can be translated into a higher sample throughput and hence reduce the laboratory operating costs. In this contribution, three different approaches for obtaining fast GC separations are investigated. First, a narrow-bore column is used under conventional GC operating conditions. Secondly, the same narrow-bore column is used under typical fast GC conditions. Here, a high oven temperature programming rate is used. The third approach uses a recent new development in GC instrumentation: Flash-2D-GC. Here the column is placed inside a metal tube, which is resistively heated. With this system, a temperature programming rate of 100°/s is possible. The results obtained with each of these three approaches are compared with results obtained on a column with conventional dimensions. This comparison takes retention times as well as plate numbers and resolution into consideration.     

快速毛细管气相色谱分析白酒中的香味成分

本文建立了快速毛细管气相色谱法,在10 min内分离了白酒中的香味成分,并对其中的醇、醛、酸、酯进行定性分析,对主要呈味成分己酸乙酯进行定量分析,方法重复性好,回收率较高。与常规毛细管色谱法相比,快速毛细管气相色谱法有效地缩短了分析时间,提高了白酒的分析效率。     

填充毛细管液相色谱-高温毛细管气相色谱在线联用分析润滑油

建立了一套填充毛细管液相色谱－高温毛细管气相色谱在线联用装置,并应用于润滑油的全组分分析。用正相填充毛细管柱液相色谱法进行样品族分离,将润滑油分成烷烃、单环芳烃、双环芳烃、三环芳烃及胶质（多环芳烃和极性物）;特殊设计的多储存位接口可完成一次ＬＣ进样,对样品所有族组成的在线切割、贮存并无损失转入ＧＣ分析,保证了复杂样品全组分分析的准确定性和定量,缩短了分析时间。ＧＣ分析结果给出各族组分的相对含量和碳数分布。     

The Use of Non-Splitting Injection Techniques for Trace Analysis in Narrow-Bore Capillary Gas Chromatography

The use of hot splitless, cold splitless, and on-column injections for trace analysis in narrow-bore capillary GC is evaluated. Despite the low flow rates for the columns used, the required splitless times for splitless injections can be surprisingly short if liners with a small inside diameter are used. On-column injection can be applied by using an appropriate normal-bore precolumn coupled to the narrow-bore analytical column using a specially designed low dead volume column connector. The effects of the experimental conditions such as sample volume, injection temperature, and initial oven temperature on peak focusing and the discrimination and degradation behavior of the analytes are discussed. The possibilities to obtain sensitive and fast separations are illustrated by various applications.     

Fast Solvating Gas Chromatography of Environmentally Important Compounds Using Polymer-Encapsulated Silica Particles

Rapid separations of selected environmentally important polar compounds using polymer-encapsulated silica stationary phases and a carbon dioxide mobile phase under solvating gas chromatography (SGC) conditions are reported. Ten underivatized short chain aldehydes and ten nitrogen-containing herbicides were separated within 1 min and 5 min, respectively, using a 30 cm×250 μm i. d. column packed with diol-bonded, polyethylenimine (PEI)-coated, and hexamethyldisilazane (HMDS)-end-capped silica particles (5 μm, 120 Å). Seven organophosphorus pesticides were resolved in less than 5 min using a 30 cm×250 μm i. d. column packed with polymethylhydrosiloxane-deactivated and SE-54 encapsulated silica particles. Separation numbers per unit time increased with pressure and temperature ramps. Both rapid pressure and temperature programming can be used to increase the speed of SGC. The effects of pressure and temperature on apparent retention factors of solutes with various polarities were investigated using diol-PEI-HMDS silica particles in SGC.     

Capillary Column Inlet System for the Gas Chromatography of Biological Samples

Abstract

A glass injection system consisting of a packed precolumn and gasphase splitter has been developed for the introduction of derivatized biological samples on glass capillary columns. The precolumn provides complete sample evaporation before the splitter zone, traps contaminating nonvolatiles, and prevents decomposition or adsorption of components. In addition, a carrier gas control system is described that permits stable and repeatable adjustment of split ratio and capillary inlet pressure.

The linearity of the splitter has been established using a hydrocarbon mixture covering the range of methylene unit (MU) values in which the steroid derivatives are eluted.     

填充毛细管液相色谱-毛细管气相色谱在线联用分析八角茴香挥发油

首次将填充毛细管高效液相色谱-毛细管气相色谱在线联用技术(μ-HPLC-CGC)用于分离分析八角茴香果实的挥发油成分。液相色谱选用氰基分析柱(250 mm×0.32 mm i.d.),正己烷-乙腈-二氯甲烷(体积比为80∶8∶12)为流动相,对挥发油样品做族组分分离,得到的5个族组分被依次存放在多位储存接口内,然后不分流分别转入毛细管气相色谱仪做详细分析。气相色谱柱由10 m×0.53 mm i.d.保留间隔柱和30 m×0.53 mm i.d.×1.0 μm SE-54分析柱组成。采用了不分流柱内进样模     

The Influence of Stop-Flow on Band Broadening of Peptides in Micro-Liquid Chromatography

Stop-flow techniques are occasionally needed in combinations of LC-NMR and LC-MS. During the interval when there is no flow on the column, axial diffusion of components not yet eluted can be expected to take place. In this paper the size of the band broadening which is caused by diffusion during stop-flow has been determined for two peptides on reversed-phase packed micro columns. Within a temperature range of 20–40 °C, stop-flow could be extended to 30 minutes for peptides having k values in the range of 0.7–5.1 with little increase in band width on 1.0 mm i.d. columns at isocratic conditions. Stop-flow for 6 h at 20 °C increased the peak width of bradykinin and leucine-enkephalin by 25% and 60%, respectively, depending on the secondary interactions of the peptides. The peak broadening increased with increasing temperature (from 20 to 40 °C), as expected, and the impact was significant at stop-flow times larger than 2 h. Stop-flow during gradient elution resulted in less increase in peak width than isocratic elution due to the peak compression obtained when re-entering the gradient. At 20 °C the effective diffusion coefficients of leucine-enkephalin and bradykinin were determined to 6.5 × 10⁻⁷cm ²/s and 5.5 × 10⁻⁷ cm²/s, respectively, on the packed micro column.     

毛细管色谱法分析二苯基二甲氧基硅烷

建立了二苯基二甲氧基硅烷毛细管气相色谱分析法。与其他测定方法进行比较,结果表明所选方法准确、精密、便捷。８次平行测定结果：Ｓ＝１．２９４×１０~（－２）％,ＣＶ＝１．３４５×１０~（－２）％。     

填充毛细管液相色谱—毛细管气相色谱在线联用分析柴油全组成

采用填充毛细管液相色谱（ＰＣ－ＨＰＬＣ）与毛管气相色谱（ＣＧＣ）在线联用技术分析柴油全组分。半填充硅胶、半填充氨基的ＰＣ－ＨＰＬＣ柱（０．３２ｍｍ ｉ．ｄ）用于样品族分离（烷烃、单环芳烃、双环芳烃、三环芳烃和胶质）。经ＰＣ－ＨＰＬＣ分离后的各族组分（峰体积小于３０μＬ）被依次存放在多位储存接口内，然后分别转入ＧＣ作单个组分定量分析，可得出各族组分的相对含量及烷烃的碳数的正异构分布。该方法是分析柴油     

电中性溶质在反相毛细管电色谱柱上峰展宽的研究

根据溶质在色谱柱中迁移的基本特征及柱分离过程弛豫理论的一般输运方程,在平衡色谱和不单独考虑逆向流的简化情况下,得到了能够说明多种因素对半峰宽影响的流出曲线的二阶中心矩表达式。通过反相毛细管电色谱实验,讨论了电压、柱长及保留因子等因素与峰展宽之间的关系,也探讨了溶质在色谱柱内峰展宽的规律。结果表明:半峰宽随柱长的增加和保留因子的增大而线性增加,随电压的增加而呈非线性减小。     

Band Broadening Function in Size Exclusion Chromatography of Polymers: Review of Some Recent Developments

Summary: This article reviews some recent developments on the determination of the Band Broadening Function (BBF) in Size Exclusion Chromatography (SEC) of polymers. It was carried out in the frame of the IUPAC Project: “Data Treatment in Size Exclusion Chromatography of Polymers”. The correction for band broadening (BB) is important for quantitative determinations of the molar mass distribution (MMD) of narrow-distributed (or highly multimodal) polymers, and of derived variables such as kinetic parameters. In the narrow range of a molar mass standard, the BBF is uniform and of positive skewness. In a broad chromatographic range, the BBF is non-uniform and skewed; and it can be adequately represented by an exponentially-modified Gaussian function (EMG) of 2 parameters that vary slightly with elution volume: an increasing Gaussian variance and a decreasing exponential decay. Additionally, the total BBF variance remains almost constant if not close to the total exclusion limit. The following methods for determining BBF parameters are reviewed: a) a direct method based on assuming Poisson-distributed MMDs; b) a direct method based on measuring the mass- and molar mass chromatograms of narrow standards; c) a theoretical method based on a stochastic model that is equivalent to the Giddings-Eyring model; and d) a theoretical method based on a deterministic model obtained through an extension of the classical van Deemter expression. Ideally, the correction for BB requires a robust numerical inversion algorithm. However, alternative simplified solutions are also possible.     

气相色谱法分析二苯基二氯硅烷

建立了分析二苯基二氯硅烷的毛细管气相色谱方法,解决了国产１１０２型气相色谱仪在分析有机硅化合物时出现的喷嘴和分流路堵塞问题。实验结果表明,方法简单、快速、准确。     

毛细管气相色谱分流进样技术研究

研究出一种改进的毛细管分流进样器，设计了一种新型螺旋进样内衬管。使分流进样的重复精度有显著提高，沸点歧视效应减小，色谱峰尾尖锐，使毛细管色谱柱的高分离效能得以充分发挥。对４种常用的进样内衬进行了考察，得到了有重要实用意义的结果，并从理论上解释了与传统观点相悖的实验现象，深化了对分流进样动态过程的理解。     

毛细管气相色谱法鉴定分析杆菌

本文利用ＯＶ－１０１熔融石英毛细管柱，对１５种标准分枝杆菌的色谱特征进行了研究，得到了特异性指纹图。并对４２株临床菌株进行了鉴别。     

水中雌激素的毛细管气相色谱分析

水中天然(雌二醇,雌酮,雌三醇)与合成(炔诺酮,炔雌醇 )的环境雌激素经固相萃取柱浓缩净化,用二氯甲烷洗脱,经N,O 双(三甲基硅烷基)三氟乙酰胺(含 1%三甲基氯硅烷)衍生化后用气相色谱法进行测定.方法检出限在 8. 25~8. 99ng/L,相对标准偏差为 2. 1% ~8. 5%,加标回收率除炔雌醇较低外,其余均大于 80%.     

毛细管气相色谱法测定染发剂中七种染料组份

采用毛细管气相色谱法对染发剂中苯酚、邻苯二酚、对苯二酚、间苯二酚、邻苯二胺、对苯二胺和间苯二胺七种染料进行了分析。结果表明，该方法能有效地分离这七种染料，其检出限为苯酚50ng、邻苯二胺160ng、对苯二胺240ng、邻苯二酚280ng、间苯二胺180ng、对苯二酚190ng、间苯二酚180ng。方法测定精密度为2.07-4.33％，回收率为96.1％-103.3％。方法具有操作准确、简单、快速、实用等特点。     

毛细管气相色谱法测定人体血清中槐定碱浓度

采用毛细管色谱柱,槐胺碱作内标,以气相色谱法建立了一种测定人体血清中槐定碱浓度的方法。最低检出浓度为０．０５ｍｇ／Ｌ,绝对回收率大于９１．７％,日内和日间变异系数小于８．９％。建立的方法已应用在肿瘤病人滴注槐定碱药物的药代动力学研究中。     

顶空毛细管气相色谱法测定吡虫啉中的丁酮

采用顶空毛细管气相色谱法测定吡虫啉中的丁酮残留量。样品经二氯甲烷溶解,用HP–5毛细管色谱柱分离,氢火焰离子化检测器检测,顶空平衡温度为70℃,平衡时间为10 min,以外标法计算含量。丁酮的质量浓度在2.0~510.0μg/m L范围内线性关系良好,相关系数r=0.999 7,方法的检出限为0.5μg/m L,样品3个水平的加标回收率为99.4%~102.1%,测定结果的相对标准偏差小于3.0%(n=5)。该方法简便快速,准确可靠,可用于吡虫啉产品的质量控制。