• Spectroscopy and Spectral Analysis
  • Vol. 39, Issue 11, 3487 (2019)
LIAN Ning1, ZHANG Ming2, ZHANG Ya-heng1, and HE Xiang-hong1
Author Affiliations
  • 1[in Chinese]
  • 2[in Chinese]
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    DOI: 10.3964/j.issn.1000-0593(2019)11-3487-06 Cite this Article
    LIAN Ning, ZHANG Ming, ZHANG Ya-heng, HE Xiang-hong. Study on Terbium Sensitized Luminescence Properties of Catecholamine and Its Application[J]. Spectroscopy and Spectral Analysis, 2019, 39(11): 3487 Copy Citation Text show less

    Abstract

    Catecholamines (Cas) plays an important role in physiological function of human body as neurotransmitter and hormone. They are organic compounds that contain an amine group and a catechol group that is constituted by a benzene ring with two hydroxyl groups at 3- and 4-positions. In physiological conditions, catecholamine mainly refers to dopamine (DA), norepinephrine (NE) and adrenaline (E). Catecholamines are chemically unstable, prone to spontaneous oxidation and decompose easily when exposed to light or air. Lanthanide sensitized luminescence is a promising tool for clinical analysis and drug analysis. In lanthanide sensitized luminescence, lanthanide ions form complexes with organic compounds, these chelates display a well-defined luminescence characterized, mainly for the determination of organic analytes. Therefore, the key to determining catecholamine by the terbium sensitization luminescence is that the analyte forms an effective and stable complex with the central ion. It is a general understanding that catecholamines form rather stable chelate complexes with metal ions, the two oxygen of the phenolic groups acting as donor atoms. Therefore, the more alkaline the solution, the stronger the complex ability of catecholamine and metal ions. In order to prevent hydroxide formation ethylenediaminetetracetic acid (EDTA) is added into the alkaline solutions, EDTA as synergistic ligand serves to chelate Tb3+ with high affinity and keeps it soluble in water, terbium ion and synergistic ligands and catecholamines form stable ternary complex soluble in water and exhibit strong characteristic fluorescence of terbium. The system with cationic surfactant cetyltrimethylammonium chloride (CTAC) as sensitizer, can make the luminescence for catecholamine chelates increased by a factor of 4 to 6. UV absorption and fluorescent spectra were used to investigate the photophysical properties of the ternary complex and energy transfer mechanism. The study shows that the catecholamine is an effective absorber of ultraviolet radiation, and the possible mechanism of the ligand sensitized fluorescence may be explained based on intramolecular energy transfer. In the energy transfer process, the ligand catecholamine absorbs the radiation energy and transfers the energy to terbium ion through intramolecular energy transfer, thus generating characteristic emission of terbium. The main factors affecting the fluorescence intensity of ternary complex, such as solution acidity, reagent adding concentration and sequence, types of surfactants and interfering substances, etc., were discussed. Under the optimized condition, the luminescence intensity of the system is linearly related to the concentration of the catecholamines. Linearity is observed in the concentration ranges of 0.080~50.0×10-6 mol·L-1 for dopamine, 0.070~50.0×10-6 mol·L-1 for norepinephrine, and 0.070~50.0×10-6 mol·L-1 for epinephrine, with limits of detection as low as 2.4×10-8, 2.2×10-8 and 2.1×10-8 mol·L-1, respectively. The proposed method has been successfully applied to the quantitative determination of the three catecholamines in a pharmaceutical preparation. Due to the advantages of narrow emission bands, large stokes shift and long excited-state lifetimes, it will be possible to investigate this method further for automated analysis, clinical pharmacokinetics study, practical diagnostic for catecholamine-related pathologies, and it can be used in HPLC and CE detectors.
    LIAN Ning, ZHANG Ming, ZHANG Ya-heng, HE Xiang-hong. Study on Terbium Sensitized Luminescence Properties of Catecholamine and Its Application[J]. Spectroscopy and Spectral Analysis, 2019, 39(11): 3487
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