Re. Galian et al., CYCLODEXTRIN ENHANCED FLUOROMETRIC METHOD FOR THE DETERMINATION OF TRYPTAMINE, Analyst (London. 1877. Print), 123(7), 1998, pp. 1587-1591
The effect of native cyclodextrins (alpha-, beta- or gamma- with six;
seven or eight glucose units, respectively), hydroxypropyl-beta-cyclod
extrin, beta-cyclodextrin solubilized in urea, soluble starch and gluc
ose in water solution on the fluorescence behaviour of tryptamine [3-(
2-aminoethyl)indole] (T) was determined. In addition, the effect of me
thanol and propanol with and without beta-cyclodextrin Or hydroxypropy
l-beta-cyclodextrin was ascertained. From the fluorescence changes wit
h pH and with beta-cyclodextrin or hydroxypropyl-beta-cyclodextrin, th
e values of the pK(a), of the ground and excited states and the associ
ation constants of T and TH [3-(2-ammoniumethyl)indole] with the two h
osts were determined. The values are pK(a), = 9.5 +/- 0.2 and pK(a) =
8.4 +/- 0.2; K-Assoc(TH) = (1.6 +/- 0.3) x 10(2) mol(-1) dm(3) and K-
Assoc(T) = (2.8 +/- 0.3) x 10(2) mol(-1) dm(3) with beta-cyclodextrin,
K-Assoc(TH) = (1.8 +/- 0.5) x 10(2) mol(-1) dm(3) and K-Assoc(T) = (4
.9 +/- 0.9) x 10(2) mol(-1) dm(3) with hydroxypropyl-beta-cyclodextrin
. The ratio of the fluorescence quantum yields for the bound and fi ee
substrate (Phi(b)/Phi(f)) were in the range 1.25-1.33, The detection
limit for the better conditions where the host-guest interactions prod
uce fluorescence enhancement was 0.454 +/- 0.002 ng ml(-1) for the com
plex T-hydroxypropyl-beta-cyclodextrin in water. The method is simpler
than others reported previously.