A universal sample injection system for capillary column GC using a programmed temperature vaporizer (PTV)

This article describes the use of a programmed temperature vaporizer injection system which overcomes many of the classical problems associated with other injection techniques employed in capillary GC. The system can be operated in three distinct modes.     

Wide-bore capillary column for the direct analysis of ethanolamines and ethylene glycols

Summary The GC separation of a mixture of three ethanolamines and four ethylene glycols without any preliminary derivatization, on a wide-bore capillary column coated with Carbowax 20M is described. These high-boiling and polar compounds elute giving simmetrical peaks and show good resolution. The analysis is completed in less than 14 minutes.     

Construction and application of a cold on-column injection system for capillary gas chromatography

A cold on-column injection system for capillary gas chromatography (GC) applications was constructed. It was based upon a conventional split/splitless capillary GC inlet, which in turn was a modification of a conventional packed GC column inlet. The heart of the laboratory constructed cold on-column inlet design was a disposable pyrex micro-sampling pipet, which functioned as a needle guide for sample injection. The sample was injected through a traditional GC septum. Construction of the injection system is described and applications are illustrated by separations of a variety of complex mixtures.     

A new type of capillary column for gas chromatography

A new type of capillary column for gas chromatography was proposed. A sorbent layer (for example, stationary liquid phase) is supported on the internal capillary surface, and the internal (interstitial) volume is packed with nonporous large particles of a sorbent (particle diameter is 0.1—0.6 of the capillary internal diameter). The external surface of the particles can also be coated with the sorbent layer (for example, stationary liquid phase). The specific separation efficiency (number of separation) on the new type column is by 1.6—2.3 times higher than that of the initial classical capillary column.     

Analysis of toxic anthraquinones and related compounds with a fused silica capillary column

In this study, application of a fused silica capillary column for analysis of toxic anthraquinones and related compounds found in plants was investigated.     

气相色谱法测定二碳酸二甲酯的纯度

选用弱极性通用毛细管色谱柱(5%苯基,95%甲基聚硅氧烷)、冷柱头进样及氢火焰离子化检测器(FID),采用程序升温,以甲基异丁酮为内标物,建立了测定二碳酸二甲酯(DMDC)纯度的气相色谱法。在优化的条件下,方法相关系数r=0.9996,检测限为0.5 mg/kg,线性范围为1.0～100 mg/kg,对实际样品进行测定,加标回收率为90.2%～98.7%,相对标准偏差为2.9%～5.2%。方法适用于食品添加剂二碳酸二甲酯的纯度分析。     

Gas chromatography of plasma amino acids using a wide bore column: Comparison with packed and capillary columns

A procedure is described in which a wide bore glass capillary column is used as an alternative to the more traditional packed column in the analysis of amino acid levels in plasma. The coefficients of variation for all amino acids (with the exception of aspartic acid) were better than 11% with recoveries ranging from 81% to 122%. The data are compared with the corresponding results obtained using a packed column and show significant differences (p < 0.005) between values for glycine, serine, isoleucine, proline, methionine, aspartic acid, phenylalanine, and lysine. A similar comparison between results from the wide bore and the fused-silica open tubular (FSOT) column shows better agreement. Adjustment of chromatographic conditions for the wide bore analysis yields results in good agreement with those from FSOT analysis but which still differe significantly from the backed column data.     

Advancing the chromatography of GC/FT-IR to WCOT capillary columns

By the use of a wide-bore WCOT capillary column, it was possible to obtain the first on-the-fly GC/FT-IR spectra with a WCOT column. This wide-bore WCOT column gave improved separation, as compared to a SCOT column, and yielded identifiable infrared spectra for a real sample.     

Single fiber-in-capillary annular column for gas chromatographic separation

A method for preparation of a stationary phase-adjustable column with in-column stationary phase-coated fused-silica fiber annular column was successfully developed. The surface of a 0.12 mm o.d. bare optical fiber was first coated with a stationary phase and then inserted into a fused-silica capillary (non-coated or coated) as an annular column for gas chromatographic study. The optical fiber and capillary were coated with polydimethylsiloxane (SE-30) and polyethylene glycol 20M (PEG-20M) as nonpolar and polar stationary phases, respectively. Among the investigated annular and open tubular columns, the PEG-20M-coated fiber-in-PEG-20M-coated capillary annular column showed the highest column efficiency with a minimum plate height of 0.35 mm and an optimum gas velocity of 25 cm/s. When a SE-30/PEG-20M-coated fiber-in-uncoated capillary annular column was applied to separate a 9-component complex mixture, the total analysis time was 5.3 min and the column length was 12 m. By contrast, when a SE-30-coated fiber-in-PEG-20M-coated capillary annular column was used to separate the same 9-component mixture, the analysis time was reduced to 3.5 min and the column length was shortened by half to 6 m. Our results show that the stationary phase-coated fiber-in-stationary phase-coated capillary annular column is a better choice for gas chromatographic separation as it is more efficient and flexible. In addition, the proposed annular column design provides flexibility in using two or even more types of stationary phases to achieve optimal analytical separation.     

大口径特厚液膜交联毛细管柱的性能和应用

本文研究了自制的内径为0.6～0.8mm液膜厚度约为5μm的二甲基聚硅氧烷交联玻璃毛细管柱的性能和应用。用氮作载气时多数柱之理论柱效利用率(UTE%)为70—80%。用正癸烷测定其样品容量为37μg。该柱可与直接进样器相连,代替填充柱直接进样作常规分析,能达到高效快速之目的。     

Application of a unique selective PLOT capillary column for the analysis of oxygenated compounds in ambient air

Summary A new PLOT column (CP-LOWOX) designed specifically for the analysis of oxygenated compounds has been used for the gas chromatographic determination of semi-volatile carbonyl compounds. The separation behavior of the new column was investigated by comparing it with the widely used non-polar polydimethylsiloxane and polar poly(ethylene glycol) columns. The CP-LOWOX column has unique selectivity for aldehydes and ketones enabling a selective separation of these analytes from predominating hydrocarbon matrices. Application of the CP-LOWOX column for the analysis of polar compounds in ambient air is demonstrated. Sampling was performed by adsorptive enrichment coupled with thermal desorption. The suitability of Tenax TA and a multi-bed adsorbent trap Carbotrap C and Carbotrap) was tested for the sampling of semivolatile carbonyl compounds. Presented at Balaton Symposium on High Performance Separation Methods, Siófok, Hungary, September 1–3, 1999     

Identification of non-branched alkenylcycloalkanes with a terminal double bond from retention index increments

Summary Reaction products of the pyrolysis of n-dodecylpentane and n-hexylcyclohexane had been separated and identified on a glass capillary column coated with Polydimethylsiloxane OV-1.The identification of the components in the pyrolysis products and of the corresponding hydrogenated samples was performed from structure retention correlations, especially retention index increments (1_CH2), homomorphy values (H^OV-1) and the temperature coefficients of retention indices (I/T). Hence the presence of homologous 1-alkenes and of monoalkenylcycloalkanes could be confirmed. Based on the addition principle of index increments the determination of the side chain structure of alkenylcycloalkanes (straight chain) and the position of the double bond was ascertained. The calculation of the retention indices of these compounds was performed with high accuracy (deviation <1 index unit). Retention indices of 10 1-alkenes, 11 monoalkenyl-cyclopentanes, 11 monoalkylcyclopentanes, 5 monoalkenylcyclohexanes and 5 monoalkylcyclohexanes were determined on the liquid phase Polydimethylsiloxane OV-1.