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  • 21
    ISSN: 1573-904X
    Schlagwort(e): chiral stationary phases ; human serum albumin ; protein binding ; binding sites ; high-performance liquid chromatography ; immobilized proteins ; chemical modification
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The in situ modification of an immobilized human serum albumin (HSA) high-performance liquid chromatographic chiral stationary phase by p-nitrophenyl acetate is reported. This procedure, which is thought to affect primarily a single reactive tyrosine residue within the protein structure, influenced the chromatographic retention and enantioselectivity factors of a wide range of solutes. For certain solutes, increases in both capacity factor and chiral resolution were observed. Ultrafiltration studies on representative test solutes using free HSA, treated in a similar manner to the immobilized protein, gave similar results as the chromatographic observations, indicating that the latter effects are not artifactual results of immobilization. The effect of the modification of HSA on the binding behavior of drugs reportedly sharing the site predominantly affected by the derivatization, namely, the indole–benzodiazepine binding site, varied greatly. This observation suggests that the affected binding area is not a single, tightly structurally defined site.
    Materialart: Digitale Medien
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  • 22
    ISSN: 1860-0980
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Psychologie
    Notizen: Abstract A modification of the Wherry-Doolittle test selection method is presented by which tests are included in a multiple correlation (obtained for a given battery of tests) in the sequence in which the rate of return in validity per unit of testing time is greatest, rather than in the order of the size of their contribution to the multiple correlation. It is proposed that the modified method can be utilized profitably when there are economic or practical limits on the time available for test administration.
    Materialart: Digitale Medien
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  • 23
    ISSN: 0899-0042
    Schlagwort(e): ifosfamide enantiomers, GC chiral stationary phase, pharmacokinetic studies, clinical validation ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An enantioselective gas chromatographic method has been developed and validated for the determination of the plasma concentration of the enantiomers of the anticancer drug ifosfamide (IFF). In this approach, the IFF enantiomers are separated from the plasma matrix by solid phase extraction, chromatographically resolved by gas chromatography on a chiral stationary phase, and detected by mass selective detection using selective ion monitoring. The assay has been validated for routine clinical and pharmacokinetic use and has a limit of detection in plasma of 250 ng/ml of each isomer.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 24
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 1-1 
    ISSN: 0899-0042
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 25
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 273-273 
    ISSN: 0899-0042
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 26
    ISSN: 0899-0042
    Schlagwort(e): stereoselective excretion ; enantioselective ; chromatography ; assay validation ; hydroxychloroquine metabolism ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A sequential achiral-chiral high-performance liquid chromatographic system has been developed for the quantitation in urine of the enantiomers of hydroxychloroquine (HCQ), and of its 3 major metabolites, desethylhydroxychloroquine (DHCQ), desethylchloroquine (DCQ), and bisdesethylchloroquine (BDCQ). HCQ and its metabolites were separated and quantified on a cyano-bonded phase, and the enantiomeric ratios were determined using a Chiral-AGP chiral stationary phase. The assay validation and application of this method to a preliminary study in a human volunteer are presented. In this subject, the initial 0-4 h urine contained the 2 HCQ enantiomers in a ratio of (+)-HCQ:(-)-HCQ of 3:2; by the 2,064 h of the study, this ratio had reversed to (+)-HCQ:(-)-HCQ of 3:7. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 27
    ISSN: 0899-0042
    Schlagwort(e): chiral high-performance liquid chromatography ; polysaccharides ; structure-retention relationships ; amides ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A series of enantiomeric amides have been chromatographed on three amylose-based chiral stationary phases (CSPs): amylose tris(3,5-dimethylphenylcarbamate) (AD-CSP), amylose tris (S-phenylethylcarbamate) (AS-CSP), and amylose tris(R-phenylethyl-carbamate) (AR-CSP). The relative retentions and enantioselectives of the solutes on the three CSPs were compared and basic structure-retention relationships developed to describe the chromatographic results. The data indicate that for these solutes the observed elution order was a function of the chirality of the amylose backbone, while the magnitude of the enantioselective separations was affected by the chirality of the carbamate side chain. Chirality 9:173-177, 1997. © 1997 Wiley-Liss, Inc.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 28
    ISSN: 0899-0042
    Schlagwort(e): salbutamol ; chiral separation ; validated assay ; fluorescence detection ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A sensitive enantioselective high-performance chromatographic (HPLC) method was developed and validated to determine low levels of (-)-R and (+)-S-albuterol in plasma. Baseline resolution was achieved by using a teicoplanin-based chiral stationary phase with a polar organic mobile phase consisting of methanol/acetonitrile/glacial acetic acid/diethylamine, 40:60:0.3:0.2, (v/v/v/v) and a flow-rate of 1.0 ml/min. Enantioselectivity (α) equaled 1.18 and resolution (Rs) equaled 1.8. By using fluorescence detection maximized at 230 and 310 nm for excitation and emission, respectively, concentrations of each enantiomer could be measured down to 125 pg/ml from a 1-ml plasma sample. Initially, the method was applied to plasma samples from a small single-dose inhalation study of racemic albuterol in a human volunteer and, later, to in vivo samples from a canine inhalation study of the single enantiomer, (-)-R-albuterol. Results from the canine study showed that no chiral inversion of (-)-R-albuterol occurs in the dog. Chirality 10:484-491, 1998. © 1998 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 29
    ISSN: 0899-0042
    Schlagwort(e): aspartame stereoisomers ; chiral separations ; column liquid chromatography ; chymotrypsin on silica ; binding sites ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The enantioselective and diastereoselective resolutions of the stereoisomers of Nα-aspartyl-phenylalanine 1-methyl ester (APME) have been accomplished on an HPLC chiral stationary phase based upon α-chymotrypsin (the ACHT-CSP) with observed enantioselectivities (α1) for the DL-/LD-enantiomers of as high as 29.17 and for the DD-/LL-enantiomers of as high as 28.97. In addition, the effect on the chromatographic retention of the APME stereoisomers of the activity of the ACHT and the composition of the mobile phase - structure of the anionic component, molarity, and pH - have been studied. The results of this study suggest that the aspartyl moiety and/or the aspartyl-phenylalanine amide linkage play key roles in the observed enantioselectivity; the APME stereoisomers containing L-phenylalanine, i.e., DL- and LL-APME, bind at a different site in the ACHT molecule (the L-Phe site) than the APME stereoisomers containing D-phenylalanine (the D-Phe site); and the observed enantioselectivity is a measure of the difference in the binding affinities at the two sites rather than the consequence of differential affinities at a single site.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 30
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 207-207 
    ISSN: 0899-0042
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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