ISSN:0935-6304    

DOI:10.1002/jhrc.1240020302

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

年代:1979

数据来源: WILEY

摘要:

AbstractCapillary gc is now rapidly expanding. Naturally, initiation is most often attempted on the basis of the experience acquired with packed columns. However, such an extrapolation is successful only if a number of essential peculiarities of capillary gc are considered. Based on practical examples this paper discusses six essential details: 1) design and maintenance of the gas flow paths, 2) the greatly increased importance of sampling technique, which should not be confined just to stream splitting, 3) the problems in quantitative analysis arising from small sample size, 4) specific sources of trouble related to small amounts of liquid phase, 5) specific arguments for the choice of the carrier gas, clearly pointing to hydrogen as the ideal carrier and, 6) the different way to approach column production. Figures for all selected examples are given.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240020303

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

年代:1979

数据来源: WILEY

摘要:

AbstractA simple, isocratic high performance liquid chromatography system (HPLC) with electrochemical detection (EC) was used to studyCannabisconstituents. SeveralCannabisextracts and reference standards were examined. A total of eleven constituents were separated, and three major cannabinoids; Δ8, Δ9tetrahydrocannabinol (THC) and cannabidiol (CBD) were identified. A linear relationship was established for the quantitation of the halucinogenic constituent Δ9THC. Minor contaminants in Δ9THC reference standard, which were not detected by gas chromatography (GC) were detected for the first time. The detection limits of Δ9THC and related cannabinoids were in the low nanogram range (2–

ISSN:0935-6304    

DOI:10.1002/jhrc.1240020304

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe present paper describes an automated system for preparative gas chromatography with glass capillary columns, controlled by a microprocessor. The effluent from the capillary column is divided by a pneumatically controlled splitter and any desired split ratio between traps and detector can be obtained. Moreover, a second pneumatic control allows instantaneous change‐over to a different split ratio, thus minimizing loss of material during collection.The effluent containing the compounds of interest is passed through a multiple manifold and collected in coiled glass capillary traps. To ensure maximum trapping efficiency even for very small amounts of material, the inner walls of the capillary traps are wetted with a suitable solvent, which gives a quantitative recovery of micro‐ and nanogram amounts of material.After repetitive sampling, sufficient amounts of material can be obtained for NMR spectroscopy and possibilities exist to enrich trace components with the aid of a double column system. Two examples of such applications are given, employing mixtures of both synthetic and natural ori

ISSN:0935-6304    

DOI:10.1002/jhrc.1240020305

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

年代:1979

数据来源: WILEY

摘要:

AbstractConventional TLC, linear and circular HPTLC are compared by using In‐situ reflectance measurements. Chromatographic resolution, time requirement and reproducibility of quantitative scanning of the different TLC methods are investigated by means of three separation problems: benzodiazepines, corticosteroids, polycyclic aromatic hydrocarbons.In all three application examples, which were chosen without prejudice, the circular developing mode with subsequent quantitative scanning showed certain advantages over the corresponding linear HPTLC techniques. These were in the case ofBenzodiazepines: Better reproducibility of quantitative assessment.Corticosteroids: Better resolution and slightly better quantitative reproducibility.Polycyclic aromatic hydrocarbons: Chromatography considerably faste

ISSN:0935-6304    

DOI:10.1002/jhrc.1240020306

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

年代:1979

数据来源: WILEY

摘要:

AbstractA procedure for determining the anthelmintic drug mebendazole in plasma of patients is described. Mebendazole together with the internal standard ciclobendazole is extracted with chloroform at pH 11. The extract is analyzed isocratically on a LiChrosorb SI 60 column with a mobile phase consisting of acetonitrile/water‐saturated chloroform/ammonia (75/92.5/0.1) at 307 nm. Reproducibility with a coefficient of variation of 3 to 10% is attainable for the concentration range of 20 to 200 ng mebendazole/ml plasma. Mebendazole plasma concentrations in patients with echinococcosis on chronic therapy with mebendazole ranged from 6 to 117 ng/m

ISSN:0935-6304    

DOI:10.1002/jhrc.1240020307

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

年代:1979

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240020308

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

年代:1979

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240020309

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

年代:1979

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240020310

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

年代:1979

数据来源: WILEY

摘要:

AbstractTrace elements in different silica gels are determined by neutron activation analysis. The presence of 20 elements in the ppm range and of 15 elements in the ppb range is established in all silica gels; even in spherical material probably obtained via an organosilicium starting material. Removal of these elements by acid treatment before and after derivatization to a reversed‐phase is studied. This is only partially effective. The resulting HPLC phases are, however, much better in cases where trace elements are detrimental. Even octadecyl derivatized silicagel can withstand boiling in 12 N hydrochloric acid without loosing significant amounts of bonded organic materia

ISSN:0935-6304    

DOI:10.1002/jhrc.1240020311

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

年代:1979

数据来源: WILEY