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  • Polymer and Materials Science  (2)
  • 1
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electroanalysis 8 (1996), S. 585-590 
    ISSN: 1040-0397
    Schlagwort(e): Lipophilic β-cyclodextrin-based ion-selective electrodes ; Local anesthetics ; Tecoflex SG80 ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 2,3,6-Trioctyl and 2,6-didodecyl-β-cyclodextrins have been incorporated in ion-selective electrodes as neutral ionophores for the detection of the local anesthetics procaine, prilocaine, lidocaine and bupivacaine hydrochlorides. Nernstian response and excellent limits of detection were observed (-log [C]≥5.0). Interference from ‘serum’ levels of sodium, potassium and calcium (150.0 mmol dm-3 Na+, 1.26 mmol dm-3 Ca2+ 4.30 mmol dm-3 K+ ), was negligible (-log Kijpot,) (overall)≥4.0). The major organic interferents were molecules of similar size and structure which caused reduced slope and drift in baseline potentials at 10 mmol dm-3 levels of concentrations. However, the interferences were substantially reduced when the interferent concentration was reduced by a factor of 10. Nernstian response was maintained in the presence of bovine serum albumin (BSA), serum (HS) and aI acid glycoprotein (AAG). A polyurethane, (Tecoflex SG80) membrane matrix was more biocompatible when compared to PVC as evidenced by lower E0 (internal) shifts with the former.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    ISSN: 1040-0397
    Schlagwort(e): Tricyclic antidepressants ; Cyclodextrin ; Amperometric ; Potentiometric ; Electrocatalysis ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Alkylated α, β and γ cyclodextrins have been incorporated in ion-selective electrodes as neutral ionophores and used for the detection of the tricyclic antidepressants imipramine, desipramine and trimipramine as their hydrochloride salts. Nernstian response and excellent potentiometric limits of detection were observed with each of the three alkylated cyclodextrins examined. Interference from ‘serum’ levels of Na+, K+ and Ca2+ ions was very low. Interference from organic molecules such as glycine, L-histidine and nicotinamide was also low in most cases (see text for exceptions). Electrodes suitable for amperometric measurements were assembled by depositing alkylated cyclodextrins on screen printed electrode substrates. Inclusion of the tricyclic antidepressants in the cyclodextrin cavity aided by controlled potential electrolysis, allowed subnanomolar levels of the analyte to be monitored by square wave voltammetry. Mechanistic studies indicated that, by preconditioning the modified electrodes at approximately +0.6 V in phosphate buffer, the appropriate radical cation was formed, which, on further conditioning at approximately -0.2 V rapidly formed the dimer which possessed a lower oxidation potential of approximately +0.18 V. Monitoring the redox wave at 0.18 V afforded a powerful analytical handle for trace analysis of these tricyclic antidepressants. This redox wave is observable only in the presence of aqueous phosphate which may be attributed to the formation of a hydrogen-bonded surface ion-pair including the substrate and a phosphate counterion.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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