槲皮素与不同浓度氢氧化钠反应的紫外-可见时间分辨吸收光谱

采用带有快门的增强型光谱探测器ICCD，对槲皮素与不同浓度NaOH的反应过程进行了实时监测，测得了浓度为5×10-5 mol·L-1的槲皮素分别与浓度为2, 0.2, 0.1, 0.04和0.02 mol·L-1的NaOH反应的紫外-可见时间分辨吸收光谱。对每种浓度，一次连续拍摄200幅，每幅光谱曝光时间为0.1 ms, 每两幅间时间间隔为前5幅20 ms，中间50幅1 s, 最后100幅2 s。实验结果表明槲皮素极易与NaOH发生反应，反应过程中有中间产物生成，对应不同浓度的反应物，反应中吸收光谱的变化是相同的，只是变化发生的时刻不同，且整个反应时间从1～100 s不等。所拍光谱图清楚地显示出槲皮素的特征峰254和374 nm的消失，槲皮素-NaOH反应过程中中间产物的吸收峰427 nm的产生和消失，及反应最终产物的吸收峰314 nm产生的过程。所获得的瞬态光谱在国内外还未见有报道，这些光谱信息为研究槲皮素和NaOH反应的微观过程提供了实验依据。

Time Resolved UV-Vis Absorption Spectra of Quercetin Reacting with Various Concentrations of Sodium Hydroxide

A real time investigation of chemical reaction process of quercetin with various concentrations of sodium hydroxide was performed by using an intensified spectroscopic detector ICCD. The time resolved UV-Vis absorption spectra of 5×10-5 mol·L-1 quercetin respectively reacting with sodium hydroxide at concentrations of 2, 0.2, 0.1, 0.04 and 0.02 mol·L-1 were acquired. A total of 200 spectra with the same exposure time of 0.1 ms for each spectrum but different time interval between two consecutive spectra were recorded for each reaction. The first 50 spectra have the time interval of 20 ms, the next 50 have 1 s, and the last 100 have 2 s. Results indicate that quercetin reacted with sodium hydroxide easily and there was an intermediate product formed during the reaction, with different concentrations of reactants, the changes of absorption bands were the same, but the moments at which the changes happened were different and the total reaction time was various from 1 s to 100 s. Spectra recorded showed the disappearing process of the typical bands centered at 254 and 374 nm of pure quercetin, the growing and disappearing processes of a new band centered at 427 nm of the intermediate product, and the growing process of the new band centered at 314 nm of the final product obviously. No other transient spectroscopic data are currently available on the reaction of quercrtin with sodium hydroxide, the results obtained in the present work provide useful experimental data for the study of the microscopic process of the reaction.