Fluorescence Spectrum Of Wood Extract And Its Application In Wood Identification

This paper mainly analyzed the properties of the fluorescence spectrum of Robinia pseudoacacia water extract,and a wood identification method based on fluorescence spectral parameters was proposed by comparing and analyzing the fluorescence spectrum of wood extracts from 6 species representing 4 generas and two families.The main results were listed as follows:(1)The effects of water,ethanol and ethyl acetate extraction solvents on the fluorescence spectrum of Robinia pseudoacacia wood were analyzed.It was found that the peak position and relative fluorescence intensity of the fluorescence spectra of the same substance in different solvents were also different.As the hydrogen bonding ability of the solvent increased,the fluorescence emission spectrum of Robinia pseudoacacia showed blue-shift.(2)The effects of storage time,extraction temperature,pH and concentration on the fluorescence spectrum of water extract from Robinia pseudoacacia were analyzed.The results of time influence showed that the characteristic peak position of fluorescence spectrum of Robinia pseudoacacia water extract did not change during the setting time of 12-60 h,but the fluorescence intensity increased with the prolongation of storage time.The results of temperature effect showed that when the extraction temperature of Robinia pseudoacacia extract ranged from 60? to 100?,the position of the characteristic peak of fluorescence spectrum did not change,but the fluorescence intensity gradually decreased with the increase of temperature.The effect of acidity on the results showed that when the pH value ranged from 1.14 to6.37,the water extract of Robinia pseudoacacia did not fluoresce,and the fluorescent component in the extract was present as a non-fluorescent body;when the pH value ranged from7.32 to 10.45,the fluorescence intensity gradually increases with the increase of pH,and the non-fluorescent body in the extract gradually transforms into fluorescent body,and the body has a relatively stable fluorescence intensity in this range;When the pH ranged from 11.47 to 12.34,the fluorescence intensity decreased with the increase of pH.Concentration effect results show that:In the concentration range of 0.20-1.00 mg/mL,the characteristic peak position of the fluorescence spectrum of the water extract of Robinia pseudoacacia remained unchanged,and there was a good linear relationship between the fluorescence intensity and the concentration,the regression line correlation coefficient “r” was 0.967.(3)Taking the quinine sulfate as reference,the fluorescence quantum yield of Robinia pseudoacacia water extract is 0.116~0.125,which proved that the Robinia pseudoacacia water extract has a high value of fluorescence analysis.(4)Comparison of the fluorescence spectra and fluorescence spectral parameters from heartwood water extracts of 6 species representing 4 generas and two families showed that there were certain differences in the spectrogram of wood extracts of each tree species,and their fluorescence spectrum characteristic parameters were clear,which could be used for qualitative identification of the species from different generas in the same family and different species in the same genera.(5)Taking Robinia pseudoacacia as research object,the reproducibility of the characteristic parameters of the fluorescence spectra of the same species from different sources was studied.The results showed that the fluorescence spectrum of the two species from different origins had very good reproducibility of the optimal excitation wavelength and fluorescence peak wavelength.The scientificity and feasibility of qualitative identification of different species of wood were further demonstrated by taking two characteristic quantities of the optimal excitation wavelength and the fluorescence peak wavelength of the fluorescence spectrum as the identification basis.