Centro de Estudos do Ambiente e do Mar (CESAM), Department of Chemistry, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
Anal Chim Acta. 2013 Jul 25;788:99-107. doi: 10.1016/j.aca.2013.05.051. Epub 2013 Jun 8.
The inner filter effects in synchronous fluorescence spectra (Δλ=60 nm) of sedimentary humic substances from a salt marsh were studied. Accordingly to their type and the influence of plant colonization, these humic substances have different spectral features and the inner filter effects act in a different manner. The fluorescence spectra of the humic substances from sediments with colonizing plants have a protein like band (λexc=280 nm) which is strongly affected by primary and secondary inner filter effects. These effects were also observed for the bands situated at longer wavelengths, i.e., at λexc=350 nm and λex=454 nm for the fulvic acids (FA) and humic acids (HA), respectively. However, they are more important for the band at 280 nm, causing spectral distortions which can be clearly seen when the spectra of solutions 40 mg L(-1) of different samples (Dissolved Organic Carbon - DOC~20 mg L(-1)) are compared with and without correction of the inner filter effects. The importance of the spectral distortions caused by inner filter effects has been demonstrated in solutions containing a mixture of model compounds which represent the fluorophores detected in the spectra of sedimentary humic samples. The effectiveness of the mathematical correction of the inner filter effects in the spectra of those solutions and of solutions of sedimentary humic substances was studied. It was observed that inner filter effects in the sedimentary humic substances spectra can be mathematically corrected, allowing to obtain a linear relationship between the fluorescence intensity and humic substances concentration and preventing distortions at concentrations as high as 50 mg L(-1) which otherwise would obscure the protein like band.
研究了盐沼沉积物中腐殖质的同步荧光光谱（Δλ=60nm）中的内滤效应。根据其类型和植物定植的影响，这些腐殖质具有不同的光谱特征，内滤效应以不同的方式起作用。具有定植植物的沉积物中腐殖质的荧光光谱具有类似于蛋白质的带（λ exc=280nm），该带受初级和次级内滤效应的强烈影响。这些效应也观察到位于较长波长处的带，即对于富里酸（FA）和腐殖酸（HA）分别为λ exc=350nm 和λ exc=454nm。然而，它们对于 280nm 处的带更为重要，导致光谱扭曲，当比较不同样品（溶解有机碳-DOC~20mg L（-1））的 40mg L（-1）溶液的光谱而不考虑内滤效应的校正时，可以清楚地看到这种光谱扭曲。在含有代表沉积物腐殖质样品光谱中检测到的荧光团的模型化合物混合物的溶液中，证明了内滤效应引起的光谱扭曲的重要性。研究了对这些溶液和沉积物腐殖质溶液的光谱进行内滤效应数学校正的有效性。观察到可以对内滤效应在沉积物腐殖质光谱中进行数学校正，从而可以在荧光强度与腐殖质浓度之间建立线性关系，并防止在高达 50mg L（-1）的浓度下发生扭曲，否则会使类似于蛋白质的带模糊不清。
