摘要:

AbstractHeptakis (3‐O‐acetyl‐2,6‐di‐O‐pentyl)‐ß‐cyclodextrin is used as a chiral stationary phase in capillary gas chromatography. High enantioselectivity towards trifluoro‐acetylated α and β‐chiral amines, amino alcohols, α‐ and β‐amino acid esters, and cyclic trans‐diols is observed. In contrast to chiral polysiloxane phases, where hydrogen bonding interaction is essential for enantiomer separation, in cyclodextrins inclusion properties contribute to enantioselectivity. This can be concluded from the separation ofN‐alkylated amino compounds. The new chiral stationary phase exhibits a wide operating temperature

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110702

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

年代:1988

数据来源: WILEY

摘要:

AbstractA high degree of deactivation of glass and fused‐silica capillary column walls is attainable by means of high temperature silylation (HTS) with or without a preceding leaching process. HTS with a phenyl containing disilazane, diphenyltetramethyldisilazane (DPTMDS), and polydimethylsiloxane (PDMS) are studied on Cab‐O‐Sil, a fumed silica, as a model substrate. Using29Si CP‐MAS NMR, it was shown that no dimethylsiloxane chains were formed upon silylation with DPTMDS under different conditions of humidity and stoichiometry at 377°C. With DPTMDS deactivation it is possible that amino trisiloxy silane groups are formed, these groups add extra activity to the surface. Silylation with a PDMS, OV 101, at various temperatures between 300°–420°C did show that dimethylsiloxane chains were bonded at the surface. Using the29Si CP‐MAS NMR technique with variable contact times to reveal siloxy group mobility, the degradation of dimethylsiloxane chains at the surface was studied. PDMS degradation at an optimal temperature gives a more effective diminuation of the silane activity caused by chemical reaction with the silanol groups and the effective screening of the remaining silanol groups with anchored polydimethylsiloxane chains and small cyclodimethylsiloxane ring structures

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110703

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

年代:1988

数据来源: WILEY

摘要:

AbstractThis study describes the use of high performance liquid chromatography (HPLC) and capillary gas chromatography/mass spectrometry (GC/MS) in the characterization of polar glucuronide conjugates of doxylamine and their subsequent aglycones following deconjugation. Rat urinary extracts which contained doxylamine and both nonconjugated and conjugated doxylamine metabolites, were examined by HPLC before and after incubation with rat intestinal microflora. The subsequent deconjugated urinary metabolites and the nonconjugated products remaining in the urinary extracts were then isolated, acetylated, and assayed by GC/MS. Incubation with the intestinal microflora indicated that anaerobic bacteria were capable of effecting hydrolytic cleavage of these polarO‐glucuronide metabolites of doxylamine and its demethylated products to their subsequent aglycones. GC/MS analysis was performed using a fused silica DB‐5 GC column and was utilized for the identification of these deconjugated metaboli

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110704

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

年代:1988

数据来源: WILEY

摘要:

AbstractA method for the derivatization of volatiles collected using the dynamic solvent effect (DSE) is described. Trimethylsily ethers and esters (usingN,O‐bis‐trimethylsilyltrifluoracetamide) are produced on the porous bed of a DSE concentrator either during or after collection of airborne volatiles. Peak areas obtained in the gas chromatographic analysis of test compounds gave coefficients of variation of less than 10% for amounts considerably less than 100 ng. Little, if any, adsorption or other loss of compounds occurs. The analysis of the volatiles collected from an individual queen of the honeybee,Apis mellifera scutellata, is presented to illustrate the utility of the techni

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110705

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

年代:1988

数据来源: WILEY

摘要:

AbstractThirteen antihistaminic drugs are separated on a CP‐Sil 5 capillary column and are evaluated by a NP detector after extraction of spiked plasma samples, alkalinized, in a solvent mixture of chloroform, dichloromethane, and methanol. Intra‐ and inter‐assay analyses showed high reliability, therefore this method can be usefully applied in experimental or clinical pharmacokinetic investiga

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110706

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

年代:1988

数据来源: WILEY

摘要:

Abstractβ‐Blocking drugs present in commercial pharmaceutical products are determined in present urine of volunteers between 4 and 24 hours after the administration of a therapeutical dose. The drugs are extracted, hydrolysed, derivatized with pentafluoropropionic anhydride, and analyzed by capillary gas chromatography and electron capture detection. Metabolite identification and drug confirmation is by capillary gas chromatography–negative ion chemical ionization mass spectrometry (GC‐NICIMS). This method is very specific and a sensitivity below 1 ng/ml is ob

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110707

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

年代:1988

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110708

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

年代:1988

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110709

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

年代:1988

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110710

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

年代:1988

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110711

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

年代:1988

数据来源: WILEY