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Issue 7, 1998
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Cyclodextrin enhanced fluorimetric method for the determination of tryptamine

Abstract

The effect of native cyclodextrins (α-, β- or γ- with six, seven or eight glucose units, respectively), hydroxypropyl-β-cyclodextrin, β-cyclodextrin solubilized in urea, soluble starch and glucose in water solution on the fluorescence behaviour of tryptamine [3-(2-aminoethyl)indole] (T) was determined. In addition, the effect of methanol and propanol with and without β-cyclodextrin or hydroxypropyl-β-cyclodextrin was ascertained. From the fluorescence changes with pH and with β-cyclodextrin or hydroxypropyl-β-cyclodextrin, the values of the pKa of the ground and excited states and the association constants of T and TH [3-(2-ammoniumethyl)indole] with the two hosts were determined. The values are pKa = 9.5 ± 0.2 and pKa* = 8.4 ± 0.2; KAssocTH = (1.6 ± 0.3) × 102 mol–1 dm3 and KAssocT = (2.8 ± 0.3) × 102 mol–1 dm3 with β-cyclodextrin, KAssocTH = (1.8 ± 0.5) × 102 mol–1 dm3 and KAssocT = (4.9 ± 0.9) × 102 mol–1 dm3 with hydroxypropyl-β-cyclodextrin. The ratio of the fluorescence quantum yields for the bound and free substrate (Φbf) were in the range 1.25–1.33. The detection limit for the better conditions where the host–guest interactions produce fluorescence enhancement was 0.454 ± 0.002 ng ml–1 for the complex T–hydroxypropyl-β-cyclodextrin in water. The method is simpler than others reported previously.

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Article type: Paper
DOI: 10.1039/A708814K
Citation: Analyst, 1998,123, 1587-1591
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    Cyclodextrin enhanced fluorimetric method for the determination of tryptamine

    R. E. Galian, A. V. Veglia and R. H. de Rossi, Analyst, 1998, 123, 1587
    DOI: 10.1039/A708814K

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