High-Pressure Gas Chromatography and Chromatography with Supercritical Fluids. I. The Effect of Pressure on Partition Coefficients in Gas-Liquid Chromatography with Carbon Dioxide as a Carrier Gas

Abstract

Gas-chromatographic experiments with CO₂ as a carrier gas, conducted at temperatures of 30 to 40°C and pressures up to 80 atm, showed a pronounced drop of the partition coefficient with increasing pressure. This effect, which can be interpreted as a raise in solute volatility, is proved to be mainly due to nonideality in the gas phase.

The gain in volatility (by a factor of 10 or more) permits gas-chromatographic separations to be carried out at lower temperatures than usual. As partition coefficients were found to drop very fast near the critical point of the carrier gas, operation at pressures well above this point may open up the possibility of handling compounds too heavy for ordinary gas-chromatographic practice.

Interesting possibilities of class separation can be deduced from the study of the pressure effect in homologous series. Some potential non-analytical applications of high-pressure gas chromatography are discussed.     

气相色谱法测定气体中的氨含量

在我公司的安全生产过程中,经常需要对系统中气体的氨含量进行测定,从而保证工艺的稳定和人员的安全.传统方法使用的是兰舒仪法,测定过程繁琐,对操作者操作技能要求比较高,测定结果容易产生偏差,同时也会增大操作人员吸入氨气中毒的风险.采用装有PORAPAK-Q色谱柱、带有TCD热导检测器的安捷伦7890气相色谱仪进行测定,测定结果准确,操作方便,更加环保安全.     

Line Shapes in Gas Chromatography. II. Nonlinear Isotherms and Mass Transfer Kinetics in Preparative Columns

Abstract

The effects of nonlinear isotherms and mass transfer kinetics on the shapes of bands in preparative gas chromatography are modeled by numerical integration of the differential equations describing solute movement. Numerical dispersion, intrinsic to the theoretical plate method, is greatly reduced by the use of asymmetrical upwind algorithms for advection. Mass transfer rate effects are taken into account by a time constant approach. The technique is readily used on microcomputers.     

气相色谱法分析邻氯氯苄

介绍了采用GC 9800 TFP气相色谱仪,石英毛细管色谱柱,使用面积修正归一法对工业邻氯氯苄进行定量测定的步骤及计算过程.该方法简便、快速、准确.     

气相色谱峰的异常现象

描述了气相色谱（GC）中常见的异常现象，按性质对它们进行了分类。讨论了异常现象各自产生的部位和原因。提出了消除异常现象的方法。     

Nonlinear Factor-Augmented Predictive Regression Models with Functional Coefficients

This article introduces a new class of functional-coefficient predictive regression models, where the regressors consist of auto-regressors and latent factor regressors, and the coefficients vary with certain index variable. The unobservable factor regressors are estimated through imposing an approximate factor model on high dimensional exogenous variables and subsequently implementing the classical principal component analysis. With the estimated factor regressors, a local linear smoothing method is used to estimate the coefficient functions (with appropriate rotation) and obtain a one-step ahead nonlinear forecast of the response variable, and then a wild bootstrap procedure is introduced to construct the prediction interval. Under regularity conditions, the asymptotic properties of the proposed methods are derived, showing that the local linear estimator and the nonlinear forecast using the estimated factor regressors are asymptotically equivalent to those using the true latent factor regressors. The developed model and methodology are further generalized to the factor-augmented vector predictive regression with functional coefficients. Finally, some extensive simulation studies and an empirical application to forecast the UK inflation are given to examine the finite-sample performance of the proposed model and methodology.     

大口径毛细管气相色谱法测定直链烷基苯碳数分布

报道了一种新的直链烷基苯碳数分布的测定方法。用大口径石英毛细管柱取代石英毛细管柱进行测定,取得了很好的实验效果。方法简便、快速、准确。     

固相萃取-气相色谱法测定水中邻苯二甲酸酯研究

利用固相萃取-气相色谱法可以对水中的邻苯二甲酸酯进行测定,该方法可以有效地对水样中的邻苯二甲酸酯进行富集,并对其进行准确的测定。笔者将对这一测定方法进行详细的介绍。     

色谱法分析煤气总硫

铂丝还原滴定法在测量干法脱硫后硫化物含量时，测量数据偏离实际结果，容易造成触媒中毒。提出了用气相色谱火焰光度检测器测定的方法，使数据更可靠、准确。     

气相色谱法测定焦炉煤气中硫化氢

用气相色谱法测定焦炉煤气中的硫化氢含量。该方法具有简便、快速等优点,准确度、精密度都较高,不受干扰物质二氧化硫的影响,完全满足成分复杂的焦炉煤气中硫化氢的测定。     

异喹啉的气相色谱分析

采取从重质吡啶中切取异喹啉原料近而提取成品异喹啉,其纯度达９７％,对其纯度采用Ａｐｉｅｚｏｎｌ固定液用２ｍ长的填充柱分析其准确度和精密度,此方法可在焦化厂进行推广。     

气相色谱法测定驱蚊剂DEET

采用大口径毛细管气相色谱法测定驱蚊剂 DEET的含量,用 CBP1－ W25－ 100（ 0.53 mm× 25 m）毛细管柱, GC－ FID进行测定。结果表明, DEET的线性相关系数为 0.9999,回收率为 98.5％～ 100.3％,该方法定量准确,简便、快速,重现性好。     

气相色谱法及其应用

气相色谱法是一种在有机化学中对易于挥发但不发生分解的化合物进行分离与分析的技术,目前其已成为现代分离分析的主要方法之一,近年来,气相色谱在各个领域都已取得很大的进步和惊人的发展。文章主要介绍气相色谱的原理、及其在石油化工、食品检测、药物分析、环境监测方面的相关应用。     

过氧化新戊酸叔丁酯的气相色谱分析法

通过气相色谱法研究了过氧化新戊酸叔丁酯,进而研究了部分其它过氧化物。这些不耐热的过氧化物不能在高温下分析。在低温下,由于有较低的蒸汽压,满意的色谱图也不易获得。因此,利用气相色谱分析时必需严格的控制相关温度。经研究得出,用PEG6000、DNP and Silicone SE-30做固定相,载气流速设为10～100mL／min,对于过氧化物的分解没有影响。过氧化新戊酸叔丁酯的分析条件：Silicone SE-30（固定液）,80℃（柱温）,10mL／min（载气流速）,萘嵌戊烷（内标物）。标准偏差0.84％,回收率99．49％。有些蒸发后立即分解的过氧化物,不能用这个方法检测。     

气相色谱法在煤化工分析中的应用

目的：随着煤化工的发展，煤化工需要通过检查煤气内各种气体的含量与使用率。方法：色相气谱仪在煤化工逐渐运用起来，其通过分离气体，检测气体等方法。结果：分析气相色谱法能够获得整个煤气的气体成分。结论：煤气是多种气体混合体，它可以通过气相色谱法进行区分。     

Stationary Spatial Temperature Gradient in Gas Chromatography

Abstract

Imposing an increasing stationary temperature gradient along the length of a gas chromatographic column is proposed as a technique for improving separation. Side outlet ports with control valves would allow the process to have the same advantages of programmed temperature gas chromatography without the disadvantages of temperature transients. For a simple model of gas chromatography the analysis provides expressions for temporal moments at any point along the column as a function of the temperature gradient. Reduced retention times, sharpening of peaks, and higher symmetry are predicted due to increasing the temperature gradient. The relationship to chromathermography is discussed.     

工业甲醇中微量乙醇的毛细管气相色谱分析

随着用户生产工艺的不断进步,对甲醇中微量乙醇的含量要求越来越严格。文章通过试验,建立了毛细管气相色谱法测定工业甲醇中微量乙醇的方法,此方法利用GC Solution工作软件-采用内标法进行定量,简单、快速、准确。     

High-Pressure Gas Chromatography and Chromatography with Supercritical Fluids. III. Fluid-Liquid Chromatography

Abstract

High-boiling substances can be separated by partition chromatography, using n-pentane and isopropanol under supercritical conditions as mobile carriers. At moderate temperatures (200–250°C) the volatility of heavy substances may be enhanced by a factor of as much as 10⁴ by increasing the pressure from atmospheric to about 50 kg/cm². This enables the analysis of compounds which are too heavy for ordinary gas chromatography.

As predicted before on the basis of gas-chromatographic studies at elevated pressures, the use of supercritical mobile fluids in combination with liquid stationary phases results in an attractive separation procedure. This technique is rapid and has a high degree of flexibility. Separations according to boiling point as well as molecular type are possible.

The main features of the new chromatographic technique, for which the designation “fluid-liquid chromatography” (FLC) is proposed, are illustrated by means of several examples.     

气相色谱法测定天然气中微量硫化物组成

利用火焰光度检测器(FPD)的气相色谱仪对气体中的微量硫化氢、羰基硫、甲硫醇、乙硫醇进行检测,该方法操作简便,分析时间短,精密度和准确度较高。