【摘要】：本文提出了一種基于銅離子選擇電極測量的熒光淬滅模型擬合方程,通過溶解性有機(jī)質(zhì)(DOM)與金屬銅絡(luò)合后的熒光衰減強(qiáng)度對自由銅含量進(jìn)行擬合,擬合結(jié)果可以代表DOM與Cu之間的條件絡(luò)合常數(shù)。在進(jìn)行腐殖酸樣品與金屬銅的熒光滴定過程中,根據(jù)熒光成分銅滴定的熒光響應(yīng)特性,運用平行因子分析法模擬熒光激發(fā)發(fā)射矩陣。同時,選用銅離子選擇電極測定每一步滴定過程中自由銅離子的濃度,并且各個成分在以自由銅含量為自變量的非線性方程擬合預(yù)測條件平衡常數(shù)時有著特定的熒光響應(yīng)。一直以來,包括最新的多組分響應(yīng)模型在內(nèi)的傳統(tǒng)熒光衰減模型均假定樣品中的總銅即為被熒光成分綁定的自由銅的總和,而沒有考慮那些不具有熒光特性的有機(jī)和無機(jī)配位體參與銅離子絡(luò)合轉(zhuǎn)化,這并不能真實反映絡(luò)合平衡的機(jī)制。本論文主要采用一種新的方法來研究標(biāo)準(zhǔn)腐殖酸樣品PPHA在pH值為6.0、7.0、8.0的磷酸鹽緩沖體系和非緩沖條件下與金屬銅的絡(luò)合綁定。平行因子分析法均識別出兩種熒光成分C1、C2,這兩種熒光成分與金屬銅的條件穩(wěn)定常數(shù)logK均隨pH值的升高而增大。在pH=6.0、7.0、8.0時,緩沖體系中,C1的logK值分別為7.11、7.89、8.04,C2的logK值分別為7.04、7.64、8.11,這種方法下的條件平衡常數(shù)比多組分響應(yīng)模型得到的平衡常數(shù)大將近兩個數(shù)量級左右；在非緩沖條件下,pH=8.0時logK1和logK2有所降低但依然較高(logK1= 7.54,logK2=7.95),兩種條件下的條件平衡常數(shù)比多元響應(yīng)模型擬合值(4.83～5.55)高出0.5個數(shù)量級左右。這表明在不同的實驗條件下,新的衰減模型方程能夠比多元響應(yīng)模型更靈敏的識別出PPHA強(qiáng)熒光結(jié)合位點。并且由與銅的有機(jī)螯合物具熒光特征的水楊酸和左旋色氨酸以及與銅綁定后不發(fā)熒光的草酸組成的混合物在pH=5.0時與銅滴定后,運用新方法的擬合結(jié)果(logKSal=3.02,logKTrp=3.71)與文獻(xiàn)中水楊酸和色氨酸的銅綁定理論值(logKSal理論=3.15,logKTrp理論=3.72)接近,很好地驗證了這種新的模型方法。在此基礎(chǔ)上,還進(jìn)行了大遼河及河口水體的天然水樣的成分分析與金屬銅的滴定,并應(yīng)用新方法體系到天然水樣當(dāng)中。成分分析結(jié)果表明,大遼河及河口中含6熒光成分,C1(ex/em=279/310(425)nm)為類酪氨酸、C2(ex/em=303/340 nm)為類色氨酸,而C3(ex/em=310/380(530)nm).C4(ex/em=325/424 nm)、C5(ex/em=380/485 nm)和C6為類腐殖質(zhì)。滴定擬合結(jié)果表明,天然海水樣品基于自由銅含量測定的新方法熒光衰減模型擬合結(jié)果次于淡水樣品的擬合結(jié)果,可能是由于海水樣品中熒光基團(tuán)處于復(fù)雜的環(huán)境中,這些基團(tuán)同金屬銅的作用過程跟淡水樣品中的作用過程不一致。
[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，

本文編號：2503795