ISSN:0935-6304    

DOI:10.1002/jhrc.1240151102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThis paper describes a method for determining both the total sulfur content and the concentration of oxygenated additives in gasoline by gas chromatography with atomic emission detection (GC‐AED). The AED provides selective detection of oxygen and sulfur compounds. Because the response factors for sulfur and oxygen are largely independent of the type of compound, calibration and determination of total element content are simplified. The use of a 0.1 mm i.d. capillary column enables complete elution of the components of the gasoline in under 10 minute

ISSN:0935-6304    

DOI:10.1002/jhrc.1240151103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThis paper describes an evaluation of the chromatographic performance of columns coated with amorphous cyclodextrin (CD) derivatives, in particular 2,3,6‐tripentyl‐β‐CD (2,3,6‐TriPe‐β‐CD), 2,6‐dipentyl‐3‐methyl‐β‐CD (2,6‐DiPe‐3‐Me‐β‐CD), and 2,6‐dimethyl‐3‐pentyl‐β‐CD (2,6‐DiMe‐3‐Pe‐β‐CD), all diluted in polysiloxane (OV‐1701 or OV‐1701‐OH), for the separation of the enantiomers of volatile compounds. 2,6‐DiMe‐3‐Pe‐β‐CD in OV‐1701 offers performance comparable with (or better than) that of the other two CDs, and without their drawbacks (inconsistency of results, as described previously).This article compares the separating ability of 2,6‐DiMe‐3‐Pe‐β‐CD and 2,3,6‐TriMe‐β‐CD, and describes the influence of the CD derivative to polysiloxane ratio, the minimum operating temperatures of the columns, and the reproducibility and cons

ISSN:0935-6304    

DOI:10.1002/jhrc.1240151104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractSample evaporation in splitless injection of large volumes is rapid: depending on the experiment, results indicate that 200 μl of hexane, for instance, evaporates in 2–10 s, producing vapor at a rate of many hundreds of milliliters per minute. A 60 × 4 mm packed bed of 20–35 mesh Tenax TA enabled injection of 200 μl volumes of all solvents tested, and even 1 ml injections were possible provided they were performed over a period of 30 s. Retention of volatile sample components depends on the sample solvent, the injection volume, and the injection speed, but only little on the injector temperature. Losses ofn‐tridecane varied from hardly 15 % (when dissolved in pentane) toca60 % (ethyl acetate); losses ofn‐heptadecane were usually below 20 %. The column temperature during injection should be at leastca20–30°C above the standard solvent

ISSN:0935-6304    

DOI:10.1002/jhrc.1240151105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractGLC on polysiloxane‐anchored permethylated β‐cyclodextrin (Chirasil‐Dex) has been used to separate the enantiomers of 106 racemates of different classes of compounds ranging from alkanes to highly polar compounds such as underivatized diols and free acids. Chromatographic data are listed and compared with those obtained by GLC on permethylated β‐cyclodextrin dissolved i

ISSN:0935-6304    

DOI:10.1002/jhrc.1240151106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractA method has been developed for calculating more accurate and reproducible equivalent chain length (ECL) values of 33 straight‐chain fatty acids (FA), with various positions and numbers ofcisdouble bonds, chromatographed on DB‐Wax and DB‐1 columns. The dependence of ECL values on the position and the number of double bonds is described, as is a method of utilizing these relationships for the characterization of FA by gas chromatog

ISSN:0935-6304    

DOI:10.1002/jhrc.1240151107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractSolid Phase Micro Extraction (SPME) involves exposing a fused silica fiber coated with stationary phase to a contaminated water sample. The organic analytes become partitioned between the stationary phase and the water and when equilibrium is reached the fiber is removed from the solution and the analytes are thermally desorbed in the injector of a gas chromatograph. The fiber is contained in a syringe to facilitate handling.Factors which affect linear range, limit of detection, and total analysis time are discussed with regard to the development of a method for analysis of volatile compounds in environmental water samples. The sensitivity of the method was determined by the thickness of the film of stationary phase; the equilibration time, however, increased with the film thickness, although it can be minimized by use of a cross‐shaped stirrer bar.Increasing the thickness of stationary phase in the analytical column enables the cryofocusing temperature to be increased from −40 to −15°C. With an ion trap mass spectrometer, detection limits required by the US Environmental Protection Agency are met for all compounds except chloromethane and chloroethane. The method has been applied to environmental water s

ISSN:0935-6304    

DOI:10.1002/jhrc.1240151108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractCoupled liquid chromatography – gas chromatography – mass spectrometry (LC‐GC‐MS) has been applied for on‐line clean up, separation, and identification of chlorinated polycyclic aromatic hydrocarbons (CI‐PAHs). A loop‐type interface was used to couple the liquid chromatograph on‐line with the GC‐MS, and concurrent solvent evaporation was used for sample transfer.A back‐flush technique was used in conjunction with a two‐dimensional column system for isolation of CI‐PAHs and polycyclic aromatic hydrocarbons (PAHs). This fraction was transferred on‐line to the GC and separated on a capillary column. Selective and sensitive detection of CI‐PAHs in the GC eluate was obtained by negative ion chemical ionization (NICI) mass spectrometry and selected ion monitoring (SIM).The combined on‐line system for isolation, separation, and identification showed high precision and accuracy, and demonstrated a linear response from 1 to 1000 pg for chlorinated PAHs. The estimated detection limit was 250 fg for 1‐chloropyrene and 1,6‐dichloropyrene.The technique was demonstrated by analysis of urban air samples. The low detection limit made it possible to use the technique for analysis of personally carried monitoring equipment for measurement of exposure t

ISSN:0935-6304    

DOI:10.1002/jhrc.1240151109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe aroma profiles of different types of low alcohol and non‐alcohol beer have been compared by collection of volatile headspace compounds on Tenax resin and GC‐MS analysis following thermal desorption. Some aroma compounds have been tentatively identified by NBS library sea

ISSN:0935-6304    

DOI:10.1002/jhrc.1240151110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractA highly stable pseudostationary phase has been synthesized and evaluated for use in micellar electrokinetic capillary chromatography (MECC). Sodium 10‐undecylenate has been oligomerized to form a micelle‐like structure following the procedure ofDurairaj et al.[1].The stability of this structure renders it suitable for use with mobile phases containing relatively high percentages of organic modifiers, enabling the separation and detection of hydrophobic analytes such as alkyl phthalates and polynuclear aromatic hydrocarbons (PAHs) which are difficult to analyze by conventional micellar electrokinetic chromatography. In addition to demonstrating the utility of this structure for the analysis of hydrophobic analytes, the electrophoretic and chromatographic properties of the new phase have been investiga

ISSN:0935-6304    

DOI:10.1002/jhrc.1240151111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY