罗丹明6G衍生物-谷胱甘肽荧光探针测定水中Hg^(2+)

Determination of Hg^(2+) in Water with Rhodamine 6G Derivative-Glutothione as Fluorescent Probe

在罗丹明6G衍生物(Rh6G2)中引入谷胱甘肽(GSH),制备了一种荧光探针Rh6G2-GSH,并基于其与Hg^(2+)识别时可发生荧光强度及吸光度的变化,分别采用荧光分光光度法和紫外-可见分光光度法测定水中Hg^(2+)的含量。在由体积比为1∶1的4-羟乙基哌嗪乙磺酸(HEPES)溶液和甲醇混合而成的缓冲溶液(pH 7)中加入Rh6G2和GSH,通过自组装反应合成荧光探针Rh6G2-GSH,将其加入到水样中,分别在优化的两种方法的仪器工作条件下测定。结果显示:荧光探针可在较宽的酸度范围内(pH 7~12)识别Hg^(2+),且受常见金属阳离子干扰小;两种方法制作的标准曲线的线性范围分别为2.5×10-5~2.5×10-4 mol·L-1和5.0×10-5~2.5×10-4 mol·L-1,检出限分别为1.39×10-9 mol·L-1和4.07×10-7 mol·L-1;对实际样品进行3个浓度水平的加标回收试验,两种方法所得的回收率分别为95.1%~120%和94.8%~100%,测定值的相对标准偏差(n=5)分别为0.46%~2.4%和0.15%~3.4%。采用四极杆-飞行时间质谱仪对荧光检测机理进行探究,发现Rh6G2-GSH在与Hg^(2+)进行不可逆的结合后,会进一步发生水解,生成一种荧光强度更高的有机酸。

Glutathione(GSH)was introduced into rhodamine 6Gderivative(R h6G2)to prepare a fluorescent probe Rh6G2-GSH,and Hg^(2+)content in water was determined by fluorescence spectroscopy and ultraviolet-visible spectrophotometry based on the changes in fluorescence intensity and absorbance occurred in the process of the fluorescent probe for recognition of Hg^(2+).Rh6G2and GSH were added into a buffer solution(pH 7.0)composed of HEPES solution and methane with volume ratio of 1∶1,and the fluorescent probe of Rh6G2-GSH was synthesized by self-assembly reaction.The fluorescent probe was mixed with the water sample,and the mixed solution was measured under the optimized instrument working conditions of the two methods.The results showed that the fluorescent probe could recognize Hg^(2+)in a wide acidity range(pH 7-12),with a less interference produced by common metal cations;linearity ranges of the standard curves made by the two methods were found in the ranges of 2.5×10-5-2.5×10-4 mol·L-1 and 5.0×10-5-2.5×10-4 mol·L-1,with detection limits of 1.39×10-9 mol·L-1 and 4.07×10-7 mol·L-1.The recovery test was made on the actual samples by standard addition method at three concentration levels,giving recoveries in the ranges of 95.1%-120%and 94.8%-100%,and RSDs of determined values(n=5)were found in the ranges of 0.46%-2.4%and 0.15%-3.4%.Quadrupole-time-of-flight mass spectrometer was used to investigate the fluorescence detection mechanism,and it turned out that after Rh6G2-GSH was irreversibly combined with Hg^(2+),it would undergo further hydrolysis to give an organic acid with a higher fluorescence intensity.