Spectrofluorimetric determination of stoichiometry and association constants of the complexes of harmane and harmine with β-cyclodextrin and chemically modified β-cyclodextrins

Martín, Laura Serrano; León, Andrés G.; Olives, Ana I.; Castillo, B. del; Martín, M. Antonia

doi:10.1016/s0039-9140(03)00066-3

Cited by 37 publications

(25 citation statements)

References 36 publications

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“…Chemiluminescence [35] or electrochemical detection methods have been employed but detection by fluorescence is most widely applied and allows analysis in the low picogram range [36][37][38]. Most recently, improved sensitivity was obtained by laser-induced fluorescence techniques [32] or cyclodextrin-complexation [39]. Mass spectrometric methods [38] using atmospheric pressure chemical ionisation [40,41] or electrospray with in-source fragmentation [42] coupled to liquid chromatography allow identification.…”

Section: Methodsmentioning

confidence: 99%

Exposure to β-carbolines norharman and harman

Pfau

Skog

2004

Journal of Chromatography B

197

170

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Section: Methodsmentioning

confidence: 99%

Exposure to β-carbolines norharman and harman

Pfau

Skog

2004

Journal of Chromatography B

197

170

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“…Since acetonitrile and methanol have been used as mobile phase components for the chromatographic separation of bcarboline alkaloids [1,7], the effect of both solvents on the amperometric response of harmane was tested. As expected, considering changes in the dielectric constant and conductivity of solutions, the peak current decreased when increased the percentage of each organic solvent in the working solution over the 5 to 40% (v/v) studied range.…”

Section: Amperometric Detection At the Cnt-gcementioning

confidence: 99%

“…The HPLC separation and determination of the b-carboline alkaloids were carried out using an isochratic elution and a C 18 reversed-phase column [1,6,7]. The mobile phase employed consisted of methanol/acetonitrile À 0.05 mol L À1 HPO 2À 4 solution of pH 9.0 [9,26].…”

Section: Lc-ec Detection At the Cnt-gcementioning

confidence: 99%

“…However, chemical derivatization to produce volatile b-carbolines is needed [4]. Moreover, HPLC combined with MS [5,6], fluorimetric [1,7,8], UV [9] or chemiluminescent [8] detection has been also used for trace determination of underivatized analytes. In spite of their electroactivity, there is a lack of electrochemical methods for the detection and quantification of these compounds.…”

Section: Introductionmentioning

confidence: 99%

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Voltammetric Characterization and Amperometric Detection of β‐Carboline Alkaloids at Carbon Nanotube‐Modified Electrodes

et al. 2007

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The voltammetric behavior of b-carboline alkaloids at carbon nanotubes-modified glassy carbon electrodes, as well as their quantification by amperometric monitoring of the oxidation responses, are reported. Cyclic voltammograms of harmane, harmine, harmaline and harmalol at the CNT-GCE showed enhanced voltammetric responses with respect to those obtained at a bare GCE. The effect of pH on the oxidation i p and E p values obtained by differential pulse voltammetry was discussed, as well as their mechanistic aspects. Hydrodynamic voltammogram of these compounds led us to select a potential value of þ 900 mV for their amperometric detection. Under these conditions, no fouling of the modified electrode surface is evidenced. The HPLC separation and determination of b-carboline alkaloids were carried out using a mobile phase consisting ofsolution of pH 9.0. Detection limits ranging between 28 nM (harmalol) and 88 nM (harmaline) were achieved. The usefulness of the chromatographic method with amperometric detection at the CNT-GCE was demonstrated by analyzing soy seeds samples spiked with harmaline, harmane and harmine at a 0.25 mg/g level.

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“…The microenvironment afforded by cyclodextrins allows to observe the emission of neutral species in aqueous solutions of harmane and harmine. The complexes have been characterized by their stoichiometry and association constants (18) and, in the case of solid complexes, by IR and NMR spectrometry techniques (19). Other analogues of β-carboline, e.g.…”

Section: Introductionmentioning

confidence: 99%

Fluorescence quenching of β‐carboline alkaloids in micellar media. A study to select the adequate surfactant to use in analytical techniques

et al. 2005

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The study of fluorescence quenching of the fluorophores allows the localization of the alkaloids (harmane and harmine) in the micelles (SDS, CTAB, Brij-35) to be established. In aqueous micellar solutions (SDS and Brij-35) at pH 13.0, emission corresponding to the neutral or zwitterionic forms can be observed. In the presence of CTAB (pH = 13.0) it was possible to observe the emission of anionic form. These species are not present in buffered aqueous solutions at these pH values. Bromide ion was added to the different surfactant solutions and the quenching effect was studied according to the Stern-Volmer equation. In the presence of SDS the quenching effect is considerably reduced compared to the aqueous solutions without surfactants, while for Brij-35 micelles were similar to those observed in homogeneous aqueous solution. For CTAB micelles a notable fluorescence quenching was observed for the different pH values studied. The fluorescence quenching studies show that the neutral species are associated inside the micelles, instead of the ionic species (cationic, zwitterionic or anionic) remaining on the surface of the micelles. The anionic surface of SDS micelles prevents the quenching effect by anionic quenchers for both neutral and charged species.

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Spectrofluorimetric determination of stoichiometry and association constants of the complexes of harmane and harmine with β-cyclodextrin and chemically modified β-cyclodextrins

Cited by 37 publications

References 36 publications

Exposure to β-carbolines norharman and harman

Exposure to β-carbolines norharman and harman

Voltammetric Characterization and Amperometric Detection of β‐Carboline Alkaloids at Carbon Nanotube‐Modified Electrodes

Fluorescence quenching of β‐carboline alkaloids in micellar media. A study to select the adequate surfactant to use in analytical techniques

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