ISSN:0935-6304    

DOI:10.1002/jhrc.1240030502

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

年代:1980

数据来源: WILEY

摘要:

AbstractStable silica gel sorbents with aliphatic or aromatic groups are formed by chemical modifications of the silanol groups with special reactive silanes. Various lipophilic surface modifications on silica gels with varying pore structures are tested with regard to their chemical and physico‐chemical characteristics, their wettability and their chromatographic retention data. The main problem in TLC is the preparation of abrasion‐resistant layers on glass or on foils which meet the usual high standard of quality and are also suited for quantitative determinations. Thin‐layer chromatography on reversed‐phase layers can only be performed if the complete wettability of the lipophilic stationary phase in dry form is guaranteed by the mobile phase. Adsorption‐chromatographic separations with lipophilic eluents and reversed‐phase partition‐chromatographic separations with hydrophilic eluents are performed, for example, with dyes, with polycyclic aromatic hydrocarbons and with lipids. The great differences in selectivity caused by the various modifications of the sorbent and the varying eluent composition are remarkable. Ready‐for‐use layers with lipophilic surface modifications complement the existing range of pre‐coated layers and thus widen the application of TLC and

ISSN:0935-6304    

DOI:10.1002/jhrc.1240030503

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

年代:1980

数据来源: WILEY

摘要:

AbstractGlass capillary columns are ideal for analysis of urinary steroid profiles (i.e. the total steroid neutral fraction without prior separation into sub‐groups).In this paper performance of both SCOT and wide‐bore WCOT columns has been compared, resulting in no significant quantitative difference on urine extracts run as trimethylsilyl ether derivatives. However, because of increased efficiency the WB‐WCOT column exhibited more sensitivity in measurement of small amounts of 11‐ox‐aetiocholanolone. Sensitivity of other steroids was greatly enhanced by use of either SCOT or WB‐WCOT, leading to an almost tenfold increase over conventional packed columns (e.g. androsterone and aetiocholanolone<40 μg per 24 h urine sample). A simple splitless injection system (based on a design of Dr. W. Greenaway, Oxford University) is presented.Experiments were also carried out using a SCOT column in conjunction with an FM‐electron capture detector. Whilst efficiency was impaired due to the design of the detector, use of He (carrier) and N2(make up gas) showed that several steroid derivatives could be easily measured at well below the 10−10g level with much more rapid retention times than with a 1½m packed column. Highly successful separation of 19 amino acids (as fluoro‐acyl derivatives) was achieved in 35 minutes using a SCOT (

ISSN:0935-6304    

DOI:10.1002/jhrc.1240030504

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe usual concepts of the dynamics of an overloaded solute band fail to explain several phenomena such as the typical “leading‐tail” shape and retention deviations exhibited by overloaded peaks, and why these defects are more commonly observed in short columns. These and other related deviations from theory can be rationalized by a non‐classical approach to the overloading phe

ISSN:0935-6304    

DOI:10.1002/jhrc.1240030505

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe potentials of unconventional capillary columns, e.g. flat, crinkled, whisker and helically coiled open‐tubular columns (HOT columns) were evaluated. In comparison to circular columns, no improvement in the column performance, when used under normal capillary GC circumstances, could be observe

ISSN:0935-6304    

DOI:10.1002/jhrc.1240030506

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

年代:1980

数据来源: WILEY

摘要:

AbstractAnalytical equations for the capacity ratio in liquid adsorption chromatography with a binary mobile phase, involving solute‐solvent and solvent‐solvent association in the mobile and surface phases, have been derived. Very simple equations have been obtained for higher values of mole fraction of the more efficient eluting solv

ISSN:0935-6304    

DOI:10.1002/jhrc.1240030507

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

年代:1980

数据来源: WILEY

摘要:

AbstractA reversed‐phase HPLC assay method was developed to determine levels of the drugs trimethoprim, sulfamethoxazole and the N4‐acetyl metabolite of the latter in human blood plasma and urine. The organic substances are extracted with ethyl acetate by a single extraction at pH 6.8. The method is rapid, accurate, sensitive and precise and well suited to routine determination of these drugs on patients during clinical pharmacokinetic investigati

ISSN:0935-6304    

DOI:10.1002/jhrc.1240030508

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

年代:1980

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240030509

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

年代:1980

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240030511

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

年代:1980

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240030501

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

年代:1980

数据来源: WILEY