ISSN:0935-6304    

DOI:10.1002/jhrc.1240141002

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

年代:1991

数据来源: WILEY

摘要:

AbstractAn experimental injection port has been designed for split or splitless sample introduction in capillary gas chromatography; the inlet uses electronic pressure control, in order that the column head pressure may be set from the GC keyboard, and the inlet may be used in the constant flow or constant pressure modes. Alternatively, the column head pressure may be programmed up or down during a GC run in a manner analogous to even temperature programming. Using electronic pressure control, a method was developed which used high column head pressures (high column flow rates) at the time of injection, followed by rapid reduction of the pressure to that required for optimum GC separation. In this way, high flow rates could be used at the time of splitless injection to reduce sample discrimination, while lower flow rates could be used for the separation. Using this method, up to 5 μl of a test sample could be injected in the splitless mode with no discrimination; in another experiment, 2.3 times as much sample was introduced into the column by using electronic pressure programming. Some GC peak broadening was observed in the first experiment

ISSN:0935-6304    

DOI:10.1002/jhrc.1240141003

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

年代:1991

数据来源: WILEY

摘要:

AbstractA small amount of a lightly sulfonated non‐porous resin placed in the liner of the injection splitter of a gas chromatograph retains basic organic compounds but allows neutral compounds to be chromatographed normally. The organic bases in the gaseous state react with sulfonic acid groups on the resin surface to form protonated ions. Abstraction of bases is complete at a base: neutral molar ratio as high as 200:1 and a large number of samples can be injected before the sulfonated resins need to be replace

ISSN:0935-6304    

DOI:10.1002/jhrc.1240141004

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

年代:1991

数据来源: WILEY

摘要:

AbstractA key feature differentiating analytical supercritical fluid extraction (SFE) from conventional liquid extraction is the possibility of varying the solvent strength of a supercritical fluid to achieve selective extractions of specific target compounds, or functional classes of compound, from complex matrices. This can be accomplished by using supercritical fluids other than carbon dioxide, for example, sulfur hexafluoride, nitrous oxide, or sulfur hexafluoride‐modified carbon dioxide. The use of these fluids will be demonstrated by the characterization of complex environmental and petroleum matrices by directly coupled SFE – capillary GC. On‐line SFE‐GC involves the decompression of pressurized extraction fluid directly into the heated, unmodified capillary split injection port of the chromatograph. This paper will also show how, by adjustment of the extraction temperature and pressure, SFE selectivity may be further e

ISSN:0935-6304    

DOI:10.1002/jhrc.1240141005

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe use of micellar electrokinetic capillary chromatography (MECC) for the analysis of the major nucleobases, nucleosides, and nucleotides, and their chemically modified derivatives, has been developed and refined. The dimensions of the separating capillaries, the composition of the buffering systems, and the conditions used for electrophoresis were investigated in order to obtain the best performance.Particular emphasis was placed on the identification of the physiological constituents of nucleic acids and their chemically modified analogs:in vitrostudies on calf thymus DNA exposed to genotoxic agents have demonstrated that adducted bases and nucleolides can be identified by MECC.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240141006

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

年代:1991

数据来源: WILEY

摘要:

AbstractA novel analytical method has been developed for the determination of lidocaine (2‐(diethylamino)‐N‐(2,6‐dimethyl)phenylacetamide) in human serum. After solvent extraction from serum the extract was analyzed by gas chromatography employing avan den Bergtype solventless injector, a new sensitive and selective detector, the surface ionization detector, and a bonded phase flexible fused silica capillary column. The detection limit wasca.30

ISSN:0935-6304    

DOI:10.1002/jhrc.1240141007

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe separation of enantiomers of rather simple molecules, such as alkanes and alkanoic acid esters substituted at the 2‐position, has been investigated on alkylated β‐cyclodextrin stationary phases. By observing the effect of varying the substrate and the cyclodextrin alkylating agent it has been possible to propose a mechanism for the separation. The most important factors seem to be hydrophobic interactions and the ability of the cyclodextrin to change its conformation to accept the guest mole

ISSN:0935-6304    

DOI:10.1002/jhrc.1240141008

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

年代:1991

数据来源: WILEY

摘要:

AbstractThis report describes the application of a computer‐aided column design and optimization program to the analysis of purgeable compounds in waste water. Series‐coupled columns with dissimilar phases can be “selectivity‐tuned” to provide the maximum separation factors, thus facilitating the most rapid analysis. A computer program calculates the column lengths and operating conditions which are required to provide the desired resolution at a specified

ISSN:0935-6304    

DOI:10.1002/jhrc.1240141009

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

年代:1991

数据来源: WILEY

摘要:

AbstractAn injector designed for automatic direct liquid injection into narrow bore capillary GC columns has been constructed and evaluated. The tip of the syringe needle is aligned with, and positioned close to, the column entrance in a small, pressurized cavity: when the sample is dispensed it is immediately forced into the column by the action of the surrounding carrier gas. A standard autosampler equipped with a standard stainless steel syringe needle was utilized for at‐column sample transfer into 100 μm i.d. columns.RSDvalues forn‐alkanes were between 0.1 and 0.3% for relative area counts and approximately 1% for absolute area co

ISSN:0935-6304    

DOI:10.1002/jhrc.1240141010

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

年代:1991

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240141011

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

年代:1991

数据来源: WILEY