Li Wen-hong, Sun Chong-mei, Wei Yong-ju
Yao Xue Xue Bao. 2015 Oct;50(10):1324-9.
Fluorescence enhancement reaction of flavoxate hydrochloride (FX) in strong alkali solution was studied, the mechanism of the reaction was investigated, and a novel fluorimetric method for analysis of FX in drug sample was established. FX has no intrinsic fluorescence, but it can slowly produce fluorescence in strong alkali solution. Heating can promote the fluorescence enhancement reaction. In 3D fluorescence spectra of the decomposition product of FX, two fluorescence peaks, located respectively at excitation wavelengths λex/ emission wavelength λem =223/410 nm, and 302/410 nm, were observed. Using quinine sulfate as a reference, fluorescence quantum yield of the decomposition product was measured to be 0.50. The structural characteriza- tion and spectral analysis of the decomposition product reveal that ester bond hydrolysis reaction of FX is firstly occurred during heating process, forming 3-methylflavone-8-carboxylic acid (MFA), then a cleavage reaction of the γ-pyrone ring of MFA occurred, producing α, β-unsaturated ketone. This product includes adjacent hydroxyl benzoic acid group in its molecule, which can form intramolecular hydrogen bond under alkaline condition, so that increase the conjugate degree and enhance the rigidity of the molecule, and thereby cause fluorescence enhancement. Based on this fluorescence enhancement reaction, a fluorimetric method was proposed for the determination of FX. A linear calibration curve covered the concentration range 0.020 3-0.487 µg · mL. The regression equation was I(F) = 23.9 + 5357.3 c, with correlation coefficient r = 0.999 7 (n = 8), detection limit D = 1.1 ng · mL(-1). The method was applied to the analysis of FX tablets, with a spiked recovery rate of 100.2%. The reliability of the method was verified by a UV-spectrophotometric method.
研究了盐酸黄酮哌酯（FX）在强碱性溶液中的荧光增强反应，探讨了反应机理，并建立了一种用于分析药物样品中FX的新型荧光分析法。FX本身无固有荧光，但在强碱性溶液中能缓慢产生荧光。加热可促进荧光增强反应。在FX分解产物的三维荧光光谱中，观察到两个荧光峰，分别位于激发波长λex/发射波长λem = 223/410 nm和302/410 nm处。以硫酸奎宁为参比，测得分解产物的荧光量子产率为0.50。分解产物的结构表征和光谱分析表明，FX在加热过程中首先发生酯键水解反应，生成3-甲基黄酮-8-羧酸（MFA），然后MFA的γ-吡喃环发生裂解反应，生成α,β-不饱和酮。该产物分子中含有相邻的羟基苯甲酸基团，在碱性条件下可形成分子内氢键，从而增加分子的共轭程度并增强分子的刚性，进而导致荧光增强。基于此荧光增强反应，提出了一种测定FX的荧光分析法。线性校准曲线的浓度范围为0.020 3 - 0.487 μg·mL 。回归方程为I(F) = 23.9 + 5357.3 c，相关系数r = 0.999 7（n = 8），检测限D = 1.1 ng·mL(-1) 。该方法应用于FX片剂的分析，加标回收率为100.2%。通过紫外分光光度法验证了该方法的可靠性。
