基于分子光谱技术和化学计量学研究DOM同金属铜的络合作用
发布时间：2019-06-21 04:40
【摘要】：本文提出了一种基于铜离子选择电极测量的荧光淬灭模型拟合方程,通过溶解性有机质(DOM)与金属铜络合后的荧光衰减强度对自由铜含量进行拟合,拟合结果可以代表DOM与Cu之间的条件络合常数。在进行腐殖酸样品与金属铜的荧光滴定过程中,根据荧光成分铜滴定的荧光响应特性,运用平行因子分析法模拟荧光激发发射矩阵。同时,选用铜离子选择电极测定每一步滴定过程中自由铜离子的浓度,并且各个成分在以自由铜含量为自变量的非线性方程拟合预测条件平衡常数时有着特定的荧光响应。一直以来,包括最新的多组分响应模型在内的传统荧光衰减模型均假定样品中的总铜即为被荧光成分绑定的自由铜的总和,而没有考虑那些不具有荧光特性的有机和无机配位体参与铜离子络合转化,这并不能真实反映络合平衡的机制。本论文主要采用一种新的方法来研究标准腐殖酸样品PPHA在pH值为6.0、7.0、8.0的磷酸盐缓冲体系和非缓冲条件下与金属铜的络合绑定。平行因子分析法均识别出两种荧光成分C1、C2,这两种荧光成分与金属铜的条件稳定常数logK均随pH值的升高而增大。在pH=6.0、7.0、8.0时,缓冲体系中,C1的logK值分别为7.11、7.89、8.04,C2的logK值分别为7.04、7.64、8.11,这种方法下的条件平衡常数比多组分响应模型得到的平衡常数大将近两个数量级左右；在非缓冲条件下,pH=8.0时logK1和logK2有所降低但依然较高(logK1= 7.54,logK2=7.95),两种条件下的条件平衡常数比多元响应模型拟合值(4.83～5.55)高出0.5个数量级左右。这表明在不同的实验条件下,新的衰减模型方程能够比多元响应模型更灵敏的识别出PPHA强荧光结合位点。并且由与铜的有机螯合物具荧光特征的水杨酸和左旋色氨酸以及与铜绑定后不发荧光的草酸组成的混合物在pH=5.0时与铜滴定后,运用新方法的拟合结果(logKSal=3.02,logKTrp=3.71)与文献中水杨酸和色氨酸的铜绑定理论值(logKSal理论=3.15,logKTrp理论=3.72)接近,很好地验证了这种新的模型方法。在此基础上,还进行了大辽河及河口水体的天然水样的成分分析与金属铜的滴定,并应用新方法体系到天然水样当中。成分分析结果表明,大辽河及河口中含6荧光成分,C1(ex/em=279/310(425)nm)为类酪氨酸、C2(ex/em=303/340 nm)为类色氨酸,而C3(ex/em=310/380(530)nm).C4(ex/em=325/424 nm)、C5(ex/em=380/485 nm)和C6为类腐殖质。滴定拟合结果表明,天然海水样品基于自由铜含量测定的新方法荧光衰减模型拟合结果次于淡水样品的拟合结果,可能是由于海水样品中荧光基团处于复杂的环境中,这些基团同金属铜的作用过程跟淡水样品中的作用过程不一致。
[Abstract]:In this paper, a fitting equation of fluorescence quenching model based on copper ion selective electrode measurement is proposed. The fluorescence attenuation intensity of dissolved organic matter (DOM) and copper is used to fit the free copper content. The fitting results can represent the conditional complexation constant between DOM and Cu. In the process of fluorescence titration of humic acid samples and metal copper, according to the fluorescence response characteristics of copper titration, the fluorescence excitation emission matrix was simulated by parallel factor analysis. At the same time, copper ion selective electrode was used to determine the concentration of free copper ion in each step of titration, and each component had a specific fluorescence response when the nonlinear equation with free copper content as independent variable was fitted to predict the conditional equilibrium constant. For a long time, the traditional fluorescence attenuation model, including the latest multicomponent response model, assumes that the total copper in the sample is the sum of free copper bound by fluorescent components, without considering the participation of organic and inorganic ligands with no fluorescence characteristics in the complexation transformation of copper ions, which can not really reflect the mechanism of complexation equilibrium. In this paper, a new method was used to study the complexation binding of standard humic acid sample PPHA with copper at pH 6.0, 7.0 and 8.0 phosphate buffer system and unbuffered condition. Two fluorescent components C1 and C2were identified by parallel factor analysis, and the conditional stability constant logK of these two fluorescent components and copper increased with the increase of pH value. At pH=6.0,7.0, 8.0, the logK values of C1 and C2 are 7.11, 7.89 and 8.04, respectively, and the logK values of C2 are 7.04, 7.64 and 8.11, respectively. the conditional equilibrium constant of this method is about two orders of magnitude larger than that obtained by the multi-component response model. Under unbuffered conditions, logK1 and logK2 decreased at pH= 8.0, but still high (logK1= 7.54, logK2 鈮，
本文编号：2503795
[Abstract]:In this paper, a fitting equation of fluorescence quenching model based on copper ion selective electrode measurement is proposed. The fluorescence attenuation intensity of dissolved organic matter (DOM) and copper is used to fit the free copper content. The fitting results can represent the conditional complexation constant between DOM and Cu. In the process of fluorescence titration of humic acid samples and metal copper, according to the fluorescence response characteristics of copper titration, the fluorescence excitation emission matrix was simulated by parallel factor analysis. At the same time, copper ion selective electrode was used to determine the concentration of free copper ion in each step of titration, and each component had a specific fluorescence response when the nonlinear equation with free copper content as independent variable was fitted to predict the conditional equilibrium constant. For a long time, the traditional fluorescence attenuation model, including the latest multicomponent response model, assumes that the total copper in the sample is the sum of free copper bound by fluorescent components, without considering the participation of organic and inorganic ligands with no fluorescence characteristics in the complexation transformation of copper ions, which can not really reflect the mechanism of complexation equilibrium. In this paper, a new method was used to study the complexation binding of standard humic acid sample PPHA with copper at pH 6.0, 7.0 and 8.0 phosphate buffer system and unbuffered condition. Two fluorescent components C1 and C2were identified by parallel factor analysis, and the conditional stability constant logK of these two fluorescent components and copper increased with the increase of pH value. At pH=6.0,7.0, 8.0, the logK values of C1 and C2 are 7.11, 7.89 and 8.04, respectively, and the logK values of C2 are 7.04, 7.64 and 8.11, respectively. the conditional equilibrium constant of this method is about two orders of magnitude larger than that obtained by the multi-component response model. Under unbuffered conditions, logK1 and logK2 decreased at pH= 8.0, but still high (logK1= 7.54, logK2 鈮，
本文编号：2503795
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